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Human mesenchymal stem cells (hMSCs) secretome has been have been at the forefront of a new wave of possible therapeutic strategies for central nervous system neurodegenerative disorders, as Parkinson's disease (PD). While within its protein fraction, several promising proteins were already identified with therapeutic properties on PD, the potential of hMSCs-secretome vesicular fraction remains to be elucidated. Such highlighting is important, since hMSCs secretome-derived vesicles can act as biological nanoparticles with beneficial effects in different pathological contexts. Therefore, in this work, we have isolated hMSCs secretome vesicular fraction, and assessed their impact on neuronal survival, and differentiation on human neural progenitors' cells (hNPCs), and in a 6-hydroxydopamine (6-OHDA) rat model of PD when compared to hMSCs secretome (as a whole) and its protein derived fraction. From the results, we have found hMSCs vesicular fraction as polydispersity source of vesicles, which when applied in vitro was able to induce hNPCs differentiation at the same levels as the whole secretome, while the protein separated fraction was not able to induce such effect. In the context of PD, although distinct effects were observed, hMSCs secretome and its derived fractions displayed a positive impact on animals' motor and histological performance, thereby indicating that hMSCs secretome and its different fractions may impact different mechanisms and pathways. Overall, we concluded that the use of the secretome collected from hMSCs and its different fractions might be active modulators of different neuroregeneration mechanisms, which could open new therapeutical opportunities for their future use as a treatment for PD., Prémios Santa Casa Neurociências Prize Mantero Belard for Neurodegenerative Diseases Research (MB-28-2019). This work was supported by the European Regional Development Fund (FEDER), through the Competitiveness Internationalization Operational Programme (POCI), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of projects UIDB/50026/2020; UIDP/50026/2020 and POCI-01-0145-FEDER-029751. This article has also been developed under the scope of the project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by ICVS Scientific Microscopy Platform, member of the national infrastructure PPBI - Portuguese Platform of Bioimaging (PPBI–POCI-01-0145-FEDER-022122), info:eu-repo/semantics/publishedVersion

Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed.

The axonal growth-restrictive character of traumatic spinal cord injury (SCI) makes finding a therapeutic strategy a very demanding task, due to the postinjury events impeditive to spontaneous axonal outgrowth and regeneration. Considering SCI pathophysiology complexity, it has been suggested that an effective therapy should tackle all the SCI-related aspects and provide sensory and motor improvement to SCI patients. Thus, the current aim of any therapeutic approach for SCI relies in providing neuroprotection and support neuroregeneration. Acknowledging the current SCI treatment paradigm, cell transplantation is one of the most explored approaches for SCI with mesenchymal stem cells (MSCs) being in the forefront of many of these. Studies showing the beneficial effects of MSC transplantation after SCI have been proposing a paracrine action of these cells on the injured tissues, through the secretion of protective and trophic factors, rather than attributing it to the action of cells itself. This manuscript provides detailed information on the most recent data regarding the neuroregenerative effect of the secretome of MSCs as a cell-free based therapy for SCI. The main challenge of any strategy proposed for SCI treatment relies in obtaining robust preclinical evidence from in vitro and in vivo models, before moving to the clinics, so we have specifically focused on the available vertebrate and mammal models of SCI currently used in research and how can SCI field benefit from them.

Adipose tissue derived stem cells (ASCs) are recognized to secret a myriad of molecules (secretome) know to modulate inflammatory response, promote axonal growth as well vascular remodeling and cellular survival. In previous works we have reported the benefit effects of ASCs transplanted to the injury site in a rat model of spinal cord injury (SCI). Emerging evidence have shown that the therapeutic actions of these cells are a consequence of their intense paracrine activity mediated by their secretome, which includes soluble bioactive molecules and vesicles. In this study, we intended to dissect the vesicular and protein individual function, comparing with whole secretome therapeutic effect. Therefore, we identified a beneficial effect of the whole secretome on neurite growth compared with protein or vesicular fraction alone and characterized their impact on microglia in vitro. Moreover, in a compression SCI mice model, from the motor tests performed, a statistical difference was found on beam balance test revealing differences in motor recovery between the use of the whole the secretome or their protein fraction. Finally, two different delivery methods, local or peripheral (IV), of ASC secretome were tested in vivo. Results indicate that when injected intravenously the secretome of ASCs has a beneficial effect on motor recovery of spinal cord injury animals compared with a single local injection and respective controls. Overall, our results showed that the whole secretome performed better than the fractions individually, raising ASC secretome mode of action as a synergy of proteic and vesicular fraction on SCI context. Also, when intravenously delivered, ASC secretome can promote SCI animal's motor recovery highlighting their therapeutic potential., The authors want to acknowledge the financial support from Prémios Santa Casa Neurociências – Prize Melo e Castro for Spinal Cord Injury Research (MC-04/17). This work was funded by FEDER, through the Foundation for Science and Technology (FCT) and national funds, under the scope of the POCI-01-0145-FEDER-029206; PTDC/MED-NEU/31417/2017; POCI-01-0145-FEDER-016739; UIDB/50026/2020 and UIDP/50026/2020. CR thanks the FCT for the contract under the Stimulus of Scientific Employment (DL57/2016 junior researcher contract). The authors acknowledge funding by Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-43/AEI/10.13039/501100011033, as well as, from the Basque Government Industry Department under the ELKARTEK program., info:eu-repo/semantics/publishedVersion

Psychiatric disorders severely impact patients’ lives. Motivational, cognitive and emotional deficits are the most common symptoms observed in these patients and no effective treatment is still available, either due to the adverse side effects or the low rate of efficacy of currently available drugs. Neurogenesis recovery has been one important focus in the treatment of psychiatric disorders, which undeniably contributes to the therapeutic action of antidepressants. However, glial plasticity is emerging as a new strategy to explore the deficits observed in mood disorders and the efficacy of therapeutic interventions. Thus, it is crucial to understand the mechanisms behind glio- and neurogenesis to better define treatments and preventive therapies, once adult cytogenesis is of pivotal importance to cognitive and emotional components of behavior, both in healthy and pathological contexts, including in psychiatric disorders. Here, we review the concepts and history of neuro- and gliogenesis, providing as well a reflection on the functional importance of cytogenesis in the context of disease.

Repair in the human nervous system is a complex and intertwined process that offers significant challenges to its study and comprehension. Taking advantage of the progress in fields such as tissue engineering and regenerative medicine, the scientific community has witnessed a strong increase of biomaterial-based approaches for neural tissue regenerative therapies. Electroactive materials, increasingly being used as sensors and actuators, also find application in neurosciences due to their ability to deliver electrical signals to the cells and tissues. The use of electrical signals for repairing impaired neural tissue therefore presents an interesting and innovative approach to bridge the gap between fundamental research and clinical applications in the next few years. In this review, first a general overview of electroactive materials, their historical origin, and characteristics are presented. Then a comprehensive view of the applications of electroactive smart materials for neural tissue regeneration is presented, with particular focus on the context of spinal cord injury and brain repair. Finally, the major challenges of the field are discussed and the main challenges for the near future presented. Overall, it is concluded that electroactive smart materials play an ever-increasing role in neural tissue regeneration, appearing as potentially valuable biomaterials for regenerative purposes., This work was supported by Prémios Santa Casa Neurociências–Prize Melo e Castro for Spinal Cord Injury Research (MC-04/17) and Portuguese Foundation for Science and Technology (Ph.D. fellowship to T. S. Pinho [PD/BDE/143150/2019]. This work was funded by national funds and FEDER, through the Foundation for Science and Technology (FCT), under the scope of the projects UIDB/50026/2020; UIDP/50026/2020; POCI-01-0145-FEDER-029206; POCI-01-0145-FEDER-031392; PTDC/MED-NEU/31417/2017; NORTE-01-0145-FEDER-029968; POCI-01-0145-FEDER-029751 POCI-01-0145-FEDER-032619. This work has also been developed under the scope of the project NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). Work supported by the Portuguese Foundation for Science and Technology (FCT): projects UID/FIS/04650/2020, PTDC/EMD-EMD/28159/2017 and PTDC/BTM-MAT/28237/2017. Financial support from the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43/AEI/10.13039/501100011033 and from the Basque Government Industry and Education Departments under the ELKARTEK and PIBA (PIBA-2018-06) programs, respectively, area also acknowledged.

Mesenchymal stromal cells (MSCs) are widely used in preclinical models of traumatic brain injury (TBI). Results are promising in terms of neurological improvement but are hampered by wide variability in treatment responses. We made a systematic review and meta-analysis: (1) to assess the quality of evidence for MSC treatment in TBI rodent models; (2) to determine the effect size of MSCs on sensorimotor function, cognitive function, and anatomical damage; (3) to identify MSC-related and protocol-related variables associated with greater efficacy; (4) to understand whether MSC manipulations boost therapeutic efficacy. The meta-analysis included 80 studies. After TBI, MSCs improved sensorimotor and cognitive deficits and reduced anatomical damage. Stratified meta-analysis on sensorimotor outcome showed similar efficacy for different MSC sources and for syngeneic or xenogenic transplants. Efficacy was greater when MSCs were delivered in the first-week post-injury, and when implanted directly into the lesion cavity. The greatest effect size was for cells embedded in matrices or for MSC-derivatives. MSC therapy is effective in preclinical TBI models, improving sensorimotor, cognitive, and anatomical outcomes, with large effect sizes. These findings support clinical studies in TBI.

Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. The neurodegeneration leading to incapacitating motor abnormalities mainly occurs in the nigrostriatal pathway due to the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Several animal models have been developed not only to better understand the mechanisms underlying neurodegeneration but also to test the potential of emerging disease-modifying therapies. However, despite aging being the main risk factor for developing idiopathic PD, most of the studies do not use aged animals. Therefore, this study aimed at assessing the effect of aging in the unilateral 6-hydroxydopamine (6-OHDA)-induced animal model of PD. For this, female young adult and aged rats received a unilateral injection of 6-OHDA into the medial forebrain bundle. Subsequently, the impact of aging on 6-OHDA-induced effects on animal welfare, motor performance, and nigrostriatal integrity were assessed. The results showed that aging had a negative impact on animal welfare after surgery. Furthermore, 6-OHDA-induced impairments on skilled motor function were significantly higher in aged rats when compared with their younger counterparts. Nigrostriatal histological analysis further revealed an increased 6-OHDA-induced dopaminergic cell loss in the SNpc of aged animals when compared to young animals. Overall, our results demonstrate a higher susceptibility of aged animals to 6-OHDA toxic insult., This research was funded by Prémios Santa Casa Neurociências—Prize Mantero Belard for Neurodegenerative Diseases Research (MB-28-2019); Portuguese Foundation for Science and Technology [Ph.D. fellowship to S.B.-A. (PD/BDE/135568/2018), B.M.-P. (SFRH/BD/120124/2016), A.M. (PDE/BDE/113598/2015), and D.S. (PD/BDE/135567/2018)]. This work was also funded by FEDER, through the Competitiveness Internationalization Operational Programme (POCI), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the projects POCI-01-0145-FEDER-007038; POCI-01-0145-FEDER-029751 and POCI-01-0145-FEDER-032619. This article has also been developed under the scope of the project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER).

Transplantation of stem cells, in particular mesenchymal stem cells (MSCs), stands as a promising therapy for trauma, stroke or neurodegenerative conditions such as spinal cord or traumatic brain injuries (SCI or TBI), ischemic stroke (IS), or Parkinson’s disease (PD). Over the last few years, cell transplantation-based approaches have started to focus on the use of cell byproducts, with a strong emphasis on cell secretome. Having this in mind, the present review discusses the current state of the art of secretome-based therapy applications in different central nervous system (CNS) pathologies. For this purpose, the following topics are discussed: (1) What are the main cell secretome sources, composition, and associated collection techniques; (2) Possible differences of the therapeutic potential of the protein and vesicular fraction of the secretome; and (3) Impact of the cell secretome on CNS-related problems such as SCI, TBI, IS, and PD. With this, we aim to clarify some of the main questions that currently exist in the field of secretome-based therapies and consequently gain new knowledge that may help in the clinical application of secretome in CNS disorders., This research was funded by Prémios Santa Casa Neurociências—Prize Melo e Castro for Spinal Cord Injury Research, grant number MC-04/17 and the Portuguese Foundation for Science and Technology (FCT) through the Scientific Employment Stimulus to N. Silva and S. Monteiro (CEECIND/04794/2017 and CEECIND/01902/2017). This work was also funded by FEDER, through the Competitiveness Internalization Operational Programme (POCI), and by National funds, through the Foundation for Sciences and Technology (FCT), under the scope of the projects POCI-01-0145-FEDER-007038, TUBITAK/0007/2014, POCI-01-0145-FEDER-029206, POCI-01-0145-FEDER-029751, and NORTE-01-0145-FEDER-029968. This work was also developed under the scope of the projects NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER).

The complex structures that make up the nervous system are susceptible to different types of injury ranging from trauma to chronic diseases that cause progressive deterioration. Consequently, the limited capacity for tissue repair in the central nervous system (CNS) is a tremendous challenge. Although spontaneous neural repair occurs in patients, this process is not robust enough to promote functional and stable recovery of the CNS architecture, demanding external intervention. Over the last 20 years, mesenchymal stem cell (MSC) therapies have been increasingly investigated to treat neurodegenerative disorders, as well as traumatic events such as spinal cord injury (SCI). While earlier studies primarily attributed the effects behind the success of MSC-based therapies to its possible neural differentiation capacity, in the last 10 years it has become evident that most of these beneficial effects are mediated by the secretome of these cells. Indeed, MSCs can secrete potent combinations of bioactive molecules including growth factors, cytokines, lipids, and extracellular vesicles, which in turn play important roles in the modulation of numerous physiological processes within the CNS. Having this in mind the review will discuss how the conceptual use MSCs in CNS regenerative medicine has evolved, as well as their proof of concept on two examples of trauma and neurodegeneration within the CNS: SCI and Parkinson’s disease (PD).

The complex structures that make up the nervous system are susceptible to different types of injury ranging from trauma to chronic diseases that cause progressive deterioration. Consequently, the limited capacity for tissue repair in the central nervous system (CNS) is a tremendous challenge. Although spontaneous neural repair occurs in patients, this process is not robust enough to promote functional and stable recovery of the CNS architecture, demanding external intervention. Stem cell (SC) therapies have been increasingly investigated for treating neurodegenerative disorders, as well as traumatic events like traumatic brain injury (TBI) or spinal cord injury (SCI). The inherent ability to self-renew and the potential to differentiate into other cell types put stem cells forward as powerful regenerative medicine tools for the treatment of these diseases. While earlier studies primarily attributed the effects behind the success of SC-based therapy to their differentiation capacity, current research has brought attention to the SC paracrine mechanisms for tissue regeneration. In fact, SCs can secrete potent combinations of bioactive molecules, including growth factors, cytokines, lipids, and extracellular vesicles, which in turn play important roles in the modulation of numerous physiological processes. Hence, the present chapter intends to provide an overview of the application of the SC secretome as a therapeutic option for distinctive CNS disorders, namely TBI, SCI, stroke, and Parkinson disease.

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder that results from the death of dopamine (DA) neurons. Over recent years, differentiated or undifferentiated neural stem cells (NSCs) transplantation has been widely used as a means of cell replacement therapy. However, compelling evidence has brought attention to the array of bioactive molecules produced by stem cells, defined as secretome. As described in the literature, other cell populations have a high-neurotrophic activity, but little is known about NSCs. Moreover, the exploration of the stem cell secretome is only in its initial stages, particularly as applied to neurodegenerative diseases. Thus, we have characterized the secretome of human neural progenitor cells (hNPCs) through proteomic analysis and investigated its effects in a 6-hydroxidopamine (6-OHDA) rat model of PD in comparison with undifferentiated hNPCs transplantation. Results revealed that the injection of hNPCs secretome potentiated the histological recovery of DA neurons when compared to the untreated group 6-OHDA and those transplanted with cells (hNPCs), thereby supporting the functional motor amelioration of 6-OHDA PD animals. Additionally, hNPCs secretome proteomic characterization has revealed that these cells have the capacity to secrete a wide range of important molecules with neuroregulatory actions, which are most likely support the effects observed. Overall, we have concluded that the use of hNPCs secretome partially modulate DA neurons cell survival and ameliorate PD animals' motor deficits, disclosing improved results when compared to cell transplantation approaches, indicating that the secretome itself could represent a route for new therapeutic options for PD regenerative medicine. Stem Cells Translational Medicine 2018;7:829-838., Portuguese Foundation for Science and Technology: Ciência 2007 Program and IF Development Grant (IF/00111/2013) to A.J.S., Ph.D. scholarships to S.I.A. (SFRH/BD/81495/ 2011); Canada Research Chair in Biomedical Engineering (LAB). This article has been developed under the scope of the project NORTE‐01‐0145‐FEDER‐000013 and NORTE‐01‐0145‐FEDER‐000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the projects POCI‐01‐0145‐FEDER‐007038, PTDC/NEU‐NMC/0205/2012, UID/NEU/04539/2013, and POCI‐01‐0145‐FEDER‐007440 cofunded by the Programa Operacional Factores de Competitividade, QREN, the European Union (FEDER), and by the National Mass Spectrometry Network under the contract REDE/1506/REM/2005, info:eu-repo/semantics/publishedVersion

Parkinson&rsquo, s Disease (PD) is characterized by the massive loss of dopaminergic neurons, leading to the appearance of several motor impairments. Current pharmacological treatments, such as the use of levodopa, are yet unable to cure the disease. Therefore, there is a need for novel strategies, particularly those that can combine in an integrated manner neuroprotection and neuroregeneration properties. In vitro and in vivo models have recently revealed that the secretome of mesenchymal stem cells (MSCs) holds a promising potential for treating PD, given its effects on neural survival, proliferation, differentiation. In the present study, we aimed to access the impact of human bone marrow MSCs (hBM-MSCs) secretome in 6-hydroxydopamine (6-OHDA) PD model when compared to levodopa administration, by addressing animals&rsquo, motor performance, and substantia nigra (SN), and striatum (STR) histological parameters by tyrosine hydroxylase (TH) expression. Results revealed that hBM-MSCs secretome per se appears to be a modulator of the dopaminergic system, enhancing TH-positive cells expression (e.g., dopaminergic neurons) and terminals both in the SN and STR when compared to the untreated group 6-OHDA. Such finding was positively correlated with a significant amelioration of the motor outcomes of 6-OHDA PD animals (assessed by the staircase test). Thus, the present findings support hBM-MSCs secretome administration as a potential therapeutic tool in treating PD, and although we suggest candidate molecules (Trx1, SEMA7A, UCHL1, PEDF, BDNF, Clusterin, SDF-1, CypA, CypB, Cys C, VEGF, DJ-1, Gal-1, GDNF, CDH2, IL-6, HSP27, PRDX1, UBE3A, MMP-2, and GDN) and possible mechanisms of hBM-MSCs secretome-mediated effects, further detailed studies are needed to carefully and clearly define which players may be responsible for its therapeutic actions. By doing so, it will be reasonable to presume that potential treatments that can, per se, or in combination modulate or slow PD may lead to a rational design of new therapeutic or adjuvant strategies for its functional modeling and repair.

Glial cells have been identified more than 100 years ago, and are known to play a key role in the central nervous system (CNS) function. A recent piece of evidence is emerging showing that in addition to the capacity of CNS modulation and homeostasis, glial cells are also being looked like as a promising cell source not only to study CNS pathologies initiation and progression but also to the establishment and development of new therapeutic strategies. Thus, in the present review, we will discuss the current evidence regarding glial cells’ contribution to neurodegenerative diseases as Parkinson’s disease, providing cellular, molecular, functional, and behavioral data supporting its active role in disease initiation, progression, and treatment. As so, considering their functional relevance, glial cells may be important to the understanding of the underlying mechanisms regarding neuronal-glial networks in neurodegeneration/regeneration processes, which may open new research opportunities for their future use as a target or treatment in human clinical trials.

The leucine-rich repeat kinase 2 (LRRK2) p.G2019S mutation is the most common genetic cause of Parkinson's disease (PD). An induced pluripotent stem cell (iPSC) line CSC-41 was generated from a 75-year old patient diagnosed with PD caused by a p.G2019S mutation in LRRK2. Skin fibroblasts were reprogrammed using a non-integrating Sendai virus-based technology to deliver OCT3/4, SOX2, c-MYC and KLF4 transcription factors. The generated iPSC line exhibits expression of common pluripotency markers, differentiates into the three germ layers and has a normal karyotype. The iPSC line can be used to explore the association between LRRK2 mutation and PD., We are greatly thankful to AnnaKarin Olden and Marianne Juhlin, for their technical assistance and to the 'Cell Line and DNA Biobank from Patients affected by Genetic Diseases' (Istituto G. Gaslini, Genova, Italy) and the Parkinson Institute Biobank, members of the Telethon Network of Genetic Biobanks (http://biobanknetwork.telethon.it; project no. GTB12001) funded by Telethon Italy, for providing fibroblasts samples. This work was supported by the Strategic Research Environment MultiPark at Lund University, the strong research environment BAGADILICO (grant 349-2007-8626), the Swedish Parkinson Foundation (Parkinsonfonden, grant 889/16), the Swedish Research Council (grant 2015-03684 to LR) and Finnish Cultural Foundation (grant 00161167 to YP). We also acknowledge the Portuguese Foundation for Science and Technology for the doctoral fellowship - PDE/BDE/113598/2015 to AM and IF Starting and Development Grants to LP and AJS (IF/00111/2013 and IF/01079/2014), respectively., info:eu-repo/semantics/publishedVersion

Patients suffering from spinal cord injury (SCI) still have a dismal prognosis. Despite all the efforts developed in this area, currently there are no effective treatments. Therefore, cell therapies have been proposed as a viable alternative to the current treatments used. Adipose tissue-derived stromal cells (ASCs) and olfactory ensheathing cells (OECs) have been used with promising results in different models of SCI, namely due to the regenerative properties of the secretome of the first, and the guidance capability of the second. Using an in vitro model of axonal growth, the dorsal root ganglia explants, we demonstrated that OECs induce neurite outgrowth mainly through cell-cell interactions, while ASCs' effects are strongly mediated by the release of paracrine factors. A proteomic analysis of ASCs' secretome revealed the presence of proteins involved in VEGF, PI3K, and Cadherin signaling pathways, which may be responsible for the effects observed. Then, the cotransplantation of ASCs and OECs showed to improve motor deficits of SCI-rats. Particular parameters of movement such as stepping, coordination, and toe clearance were improved in rats that received the transplant of cells, in comparison to nontreated rats. A histological analysis of the spinal cord tissues revealed that transplantation of ASCs and OECs had a major effect on the reduction of inflammatory cells close the lesion site. A slight reduction of astrogliosis was also evident. Overall, the results obtained with the present work indicate that the cotransplantation of ASCs and OECs brings important functional benefits to the injured spinal cord. Stem Cells 2018;36:696-708., This article is a result of the project (NORTE-01-0145-FEDER-000013), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Cofinanciado pelo Programa Operacional Regional do Norte (ON.2 SR&TD Integrated Program – NORTE-07-0124-FEDER- 000021), ao abrigo do Quadro de Referência Estrategico Nacional (QREN), através do Fundo Europeu de Desenvolvimento Regional (FEDER); Projeto Estrategico – LA 26 – 2011–2012 and Projeto Estratégico – LA 26 – 2013-2014 cofinan- ciado por fundos nacionais, através da Fundação para a Ciência e a Tecnologia (PEst-C/SAU/LA0026/2011; PEst-C/SAU/LA0026/2013), e pelo Fundo Europeu de DesenvolvimentoRegional (FEDER), através do COMPETE (FCOMP-01-0124- FEDER-022724; FCOMP-01-0124-FEDER-037298 ). Support also from PTDC/NEU-SCC/7051/2014; POCI-01-0145-FEDER-007440; PTDC/NEU-NMC/0205/2012; UID/NEU/04539/2013; The National Mass Spectrometry Network (RNEM) (REDE/1506/ REM/2005). This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the pro- ject POCI-01-0145-FEDER-0070, info:eu-repo/semantics/publishedVersion

Integrins are cell adhesion receptors predominantly important during normal and tumor angiogenesis. A sequence present on several extracellular matrix proteins composed of Arg-Gly-Asp (RGD) has attracted attention due to its role in cell adhesion mediated by integrins. The development of ligands that can bind to integrins involved in tumor angiogenesis and brake disease progression has resulted in new investigational drug entities reaching the clinical trial phase in humans. The use of integrin-specific ligands can be useful for the vascularization of regenerative medicine constructs, which remains a major limitation for translation into clinical practice. In order to enhance vascularization, immobilization of integrin-specific RGD peptidomimetics within constructs is a recommended approach, due to their high specificity and selectivity towards certain desired integrins. This review endeavours to address the potential of peptidomimetic-coated biomaterials as vascular network promoters for regenerative medicine purposes. Clinical studies involving molecules tracking active integrins in cancer angiogenesis and reasons for their failure are also addressed., Prémios Santa Casa Neurociências - Prize Melo e Castro for Spinal Cord Injury Research; Portuguese Foundation for Science and Technology [Doctoral fellowship (PD/BDE/127835/2016) to L. A. Rocha; IF Development Grant to A. J. Salgado; national funds through grant TUBITAK/0007/2014]. This article has been developed under the scope of the projects NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER); This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038, info:eu-repo/semantics/publishedVersion

The authors want to acknowledge the financial support from Premios Santa Casa Neurociencias ‐ Prize Melo e Castro for Spinal Cord Injury Research (MC-04/17); from Portuguese Foundation for Science and Technology [Doctoral fellowship (SFRH/BD/103075/2014) to EDG; Post‐ Doctoral fellowship (SFRH/BPD/97701/2013) to NAS; IF Development Grant to AJS]. This work is funded by national funds through FCT under the scope of grant reference TUBITAK/0007/2014 and 3599-PPCDT Project: PTDC/DTP-FTO/5109/2014. This article has been developed under the scope of the projects NORTE-01-0145- FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01- 0145-FEDER-007038.

Background: Glioblastoma (GBM) is a highly aggressive primary brain cancer, for which curative therapies are not available. An emerging therapeutic approach suggested to have potential to target malignant gliomas has been based on the use of multipotent mesenchymal stem cells (MSCs), either unmodified or engineered to deliver anticancer therapeutic agents, as these cells present an intrinsic capacity to migrate towards malignant tumors. Nevertheless, it is still controversial whether this innate tropism of MSCs towards the tumor area is associated with cancer promotion or suppression. Considering that one of the major mechanisms by which MSCs interact with and modulate tumor cells is via secreted factors, we studied how the secretome of MSCs modulates critical hallmark features of GBM cells. Methods: The effect of conditioned media (CM) from human umbilical cord perivascular cells (HUCPVCs, a MSC population present in the Wharton's jelly of the umbilical cord) on GBM cell viability, migration, proliferation and sensitivity to temozolomide treatment of U251 and SNB-19 GBM cells was evaluated. The in vivo chicken chorioallantoic membrane (CAM) assay was used to evaluate the effect of HUCPVCs CM on tumor growth and angiogenesis. The secretome of HUCPVCs was characterized by proteomic analyses. Results: We found that both tested GBM cell lines exposed to HUCPVCs CM presented significantly higher cellular viability, proliferation and migration. In contrast, resistance of GBM cells to temozolomide chemotherapy was not significantly affected by HUCPVCs CM. In the in vivo CAM assay, CM from HUCPVCs promoted U251 and SNB-19 tumor cells growth. Proteomic analysis to characterize the secretome of HUCPVCs identified several proteins involved in promotion of cell survival, proliferation and migration, revealing novel putative molecular mediators for the effects observed in GBM cells exposed to HUCPVCs CM. Conclusions: These findings provide novel insights to better understand the interplay between GBM cells and MSCs, raising awareness to potential safety issues regarding the use of MSCs as stem-cell based therapies for GBM., The authors would like to acknowledge the funding agencies that supported this work: Fundacao para a Ciencia e Tecnologia (FCT), Portugal, projects reference: PTDC/SAU-GMG/113795/2009 (BMC); SFRH/BD/88121/2012 (JVdC); SFRH/BD/103075/2014 (EDG); IF/00601/2012 (BMC); IF/00111/2013 (AJS); SFRH/BD/81495/2011 (SIA); PTDC/NEU-NMC/0205/2012, PTDC/NEUSCC/ 7051/2014, PEst-C/SAU/LA0001/2013-2014 and UID/NEU/04539/2013 (BM); Fundacao Calouste Gulbenkian (BMC); Liga Portuguesa Contra o Cancro (BMC); " COMPETE Programa Operacional Factores de Competitividade, QREN, the European Union (FEDER-Fundo Europeu de Desenvolvimento Regional) and by The National Mass Spectrometry Network (RNEM) under the contract REDE/1506/REM/2005; FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038; and project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). The funding body did not have a role in the design of the study, in collection, analysis or interpretation of data, or in writing the manuscript.

The central nervous system (CNS) has a limited auto-regeneration capacity, which makes it challenging for the development of new therapies. Previous studies from our lab have demonstrated the applicability of human bone marrow mesenchymal stem cells (hBM-MSCs) secretome as a possible therapeutic tool for CNS. Astrocytes, glial cells present in all brain regions, are important players in brain function through their vast influence in extracellular homeostasis, neuro-vascular regulation, synaptic modulation and neurogenesis. Thus, in the present work, we aimed to evaluate the specific impact of MSCs secretome on hippocampal proliferation and astrocyte morphology, in both WT and dnSNARE mice, a transgenic model that presents impaired astrocytic exocytosis and consequently impaired astrocytic function. Results demonstrated increased levels of proliferation for WT when treated with secretome. Additionally, it was possible to observe that dnSNARE animals injected with hBM-MSCs secretome disclosed increased levels of proliferating GFAP stained cells at the SGZ. Morphometrical evaluation found increased process hypertrophy and branching of dnSNARE astrocytes when treated with secretome. These results are closely related with the trophic factors present in the secretome, namely FGF-2, BDNF, GDNF, IGF-1, VEGF, CADH2, PEDF and miR-16. Moreover, the impaired exocytosis of astrocytes may also have implications for the response to the proliferative stimulus, given the established autocrine signaling through this mechanism.

The authors acknowledge the financial support of Premios Santa Casa Neurociencias—Prize Melo e Castro for Spinal Cord Injury Research; Portuguese Foundation for Science and Technology: [Financiado no âmbito do Projecto 3599—Promover a Producao Cientifica e Desenvolvimento Tecnologico e a Constituicao de Redes Tematicas (3599-PPCDT), project: PTDC/DTP-FTO/5109/2014]; Doctoral fellowship (SFRH/BD/103075/2014) to E.D. Gomes; Doctoral fellowship (PDE/BDE/113596/2015) to R.C. Assuncao-Silva; Post-Doctoral fellowship (SFRH/BPD/97701/2013) to N.A. Silva; IF Development Grant to A.J. Salgado (IF/ 00111/2013); by national funds through grant TUBITAK/0007/2014. This article was developed under the scope of the project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work was funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038.

Magnetic fields with different frequency and intensity parameters exhibit a wide range of effects on different biological models. Extremely low frequency magnetic field (ELF MF) exposure is known to augment or even initiate neuronal differentiation in several in vitro and in vivo models. This effect holds potential for clinical translation into treatment of neurodegenerative conditions such as autism, Parkinson's disease and dementia by promoting neurogenesis, non-invasively. However, the lack of information on underlying mechanisms hinders further investigation into this phenomenon. Here, we examine involvement of glutamatergic Ca2+ channel, N-methyl-D-aspartate (NMDA) receptors in the process of human neuronal differentiation under ELF MF exposure. We show that human neural progenitor cells (hNPCs) differentiate more efficiently under ELF MF exposure in vitro, as demonstrated by the abundance of neuronal markers. Furthermore, they exhibit higher intracellular Ca2+ levels as evidenced by c-fos expression and more elongated mature neurites. We were able to neutralize these effects by blocking NMDA receptors with memantine. As a result, we hypothesize that the effects of ELF MF exposure on neuronal differentiation originate from the effects on NMDA receptors, which sequentially triggers Ca2+-dependent cascades that lead to differentiation. Our findings identify NMDA receptors as a new key player in this field that will aid further research in the pursuit of effect mechanisms of ELF MFs., European Molecular Biology Organization Short Term Fellowships, ASTF 7502. This work was partially supported by TUBITAK Projects under Grant No. 117Z864, Bogazici University Research Fund by Grant Number 6701. A.J. Salgado and A. Marote acknowledge the financial support from: Prémios Santa Casa Neurociências–Prize Melo e Castro for Spinal Cord Injury Research (MC-04/17); Portuguese Foundation for Science and Technology Pre–Doctoral fellowship to A. Marote PDE/BDE/113598/2015 and IF Development Grant to A. J. Salgado. This work is funded by national funds through FCT under the scope of grant reference TUBITAK/0007/2014. This article has been developed under the scope of the projects NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038 and POCI-01-0145-FEDER-029206

Motor uncoordination is one of the symptoms of spinocerebellar ataxia type 3/ Machado-Joseph disease (MJD), for which there is no effective treatment. In recent years, stem-cell related therapies begun to be explored for the treatment of neurodegenerative diseases. Beyond their potential for cell replacement therapies, stem cells also act as immunomodulators and neuroprotectors. Despite the evidence of beneficial outcomes in this context, the short duration of the pre and clinical trials and the fact that most patients regressed to the disease stage prior to treatment, highlights the urgency to assess therapeutic efficacy in a chronic fashion. The purpose of this study was to compare the therapeutic efficacy of hMSC transplantation versus administration of their secretome in different disease-relevant regions of the CNS, using a mouse model of MJD. We observed a more marked and sustained therapeutic benefit with hMSC transplantation into the cerebellum when compared to substantia nigra/ striatum or the spinal cord, or to administration of MSC secretome. Funding Statement: This work has been funded the National Ataxia Foundation (NAF), by FEDER, through the Competitiveness Factors Operational Programme (COMPETE), project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, and by National funds through the Foundation for Science and Technology (FCT) under the scope of the project UID/Multi/50026/2019 and fellowships to A.N-C., B. M-P., J. S. C., F. G. T., N. S., R. L., and S. D-S. (SFRH/BPD/118779/2016, SFRH/BD/120124/2016, SFRH/BD/140624/2018, SFRH/BPD/118408/2016, CEECIND/04794/2017, PD/BDE/127836/2016 and PTDC/NEUNMC/3648/2014). Declaration of Interests: The authors have no conflict of interests to report. Ethics Approval Statement: All procedures were conducted in accordance with European regulations (European Union Directive 86/609/EEC). Animal facilities and the people directly involved in animal experiments (A.N.C, B.M.P, J.S.C., S.D.S, S.M., F.G.T, F.L., R.L., N.A.S) as well as the principal investigators (A.J.S. and P.M.) were certified by the Portuguese regulatory entity Direcao Geral de Alimentacao e Veterinaria. All the protocols performed were approved by the Animal Ethics Committee of the Life and Health Sciences Research Institute, University of Minho (Braga, Portugal) and by the national regulatory agency, Direcao Geral de Alimentacao e Veterinaria (DGAV 020317).

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Clinically, it is characterized by severe motor complications caused by a progressive degeneration of dopaminergic neurons (DAn) and dopamine loss. Current treatment is focused on mitigating the symptoms through administration of levodopa, rather than on preventing DAn damage. Therefore, the use and development of neuroprotective/disease-modifying strategies is an absolute need, which can lead to promising gains on PD translational research. Mesenchymal stem cells (MSCs)–derived exosomes have been proposed as a promising therapeutic tool, since it has been demonstrated that they can act as biological nanoparticles with beneficial effects in different pathological conditions, including PD. Thus, considering their potential protective action in lesioned sites, MSCs-derived exosomes might also be active modulators of the neuroregeneration processes, opening a door for their future use as therapeutical strategies in human clinical trials. Therefore, in this review, we analyze the current understanding of MSCs-derived exosomes as a new possible therapeutic strategy for PD, by providing an overview about the potential role of miRNAs in the cellular and molecular basis of PD., This research was funded by Portuguese Foundation for Science and Technology(FCT): IF Development Grant (IF/00111/2013) to AJ Salgado) and Post-Doctoral Fellowship to F.G. Teixeira (SFRH/BPD/118408/2016). This article has been developed under the scope of the project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by FEDER funds, through the Competitiveness Internationalization Operational Programme (POCI), and by National funds, through FCT, under the scope of the projects POCI-01-0145-FEDER-007038 and POCI-01-0145-FEDER-029751., info:eu-repo/semantics/publishedVersion

Mesenchymal stem cells (MSCs), and within them adipose tissue derived stem cells (ASCs), have been shown to have therapeutic effects on central nervous system (CNS) cell populations. Such effects have been mostly attributed to soluble factors, as well as vesicles, present in their secretome. Yet, little is known about the impact that MSC passaging might have in the secretion therapeutic profile. Our aim was to show how human ASCs (hASCs) passage number influences the effect of their secretome in neuronal survival, differentiation and axonal growth. For this purpose, post-natal rat hippocampal primary cultures, human neural progenitor cell (hNPCs) cultures and dorsal root ganglia (DRGs) explants were incubated with secretome, collected as conditioned media (CM), obtained from hASCs in P3, P6, P9 and P12. Results showed no differences when comparing percentages of MAP-2 positive cells (a mature neuronal marker) in neuronal cultures or hNPCs, after incubation with hASCs secretome from different passages. The same was observed regarding DRG neurite outgrowth. In order to characterize the secretomes obtained from different passages, a proteomic analysis was performed, revealing that its composition did not vary significantly with passage number P3 to P12. Results allowed us to identify several key proteins, such as pigment epithelium derived factor (PEDF), DJ-1, interleucin-6 (IL-6) and galectin, all of which have already proven to play neuroprotective and neurodifferentiating roles. Proteins that promote neurite outgrowth were also found present, such as semaphorin 7A and glypican-1. We conclude that cellular passaging does not influence significantly hASCs's secretome properties especially their ability to support post-natal neuronal survival, induce neurodifferentiation and promote axonal growth., Prémios Santa Casa Neurociências - Prize Melo e Castro for Spinal Cord Injury Research (MC-17-2013 and MC-04-2017), Canada Research Chair in Biomedical Engineering (LAB), Northern Portugal Regional Operational Programme (NORTE 2020),, European Regional Development Fund (FEDER), Competitiveness Factors Operational Programme (COMPETE), National Mass Spectrometry Network (RNEM), info:eu-repo/semantics/publishedVersion

In recent years, we have witnessed a significant increase in the amount of studies using Mesenchymal Stem Cells (MSCs) for cancer therapy, mostly as vectors for drug or gene delivery strategies. This is because of their intrinsic capacity of homing into tumor niches. However, the interactions between MSCs themselves and tumor cells is not fully understood, with contradictory results frequently being observed regarding their effects on cancer cell invasion and proliferation. This poses an important question of safety in respect to the application of these cells. The source of the MSC population used, as well as the type of cancer cells under study might strongly influence this interaction. Moreover, differences in isolation protocols, culture media compositions, time of culture and conditioned media collection, or even timing and mode of MSCs administration to in vivo models of cancer may also affect the interaction MSC-tumor cells. In this review, we drive our focus into malignant brain tumors, particularly gliomas, one of the deadliest forms of cancer. Moreover, we look with some detail into different studies using MSCs as a treatment for brain tumors and compare them, highlighting the main deviations and similarities among them., Portuguese Foundation for Science and Technology: pre- doctoral fellowship to E.D. Gomes (SFRH/BD/103075/2014) and J. Vieira de Castro (SFRH/BD/88121/2012); FCT Investigator Starting Grant to B.M. Costa (IF/00601/2012); FCT Investigator Development Grant to A.J. Salgado (IF/00111/2013). This article has been devel- oped under the scope of the project NORTE-01-0145-FEDER- 000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has also been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145- FEDER-007038, info:eu-repo/semantics/acceptedVersion

Mutations in the glucocerebrosidase (GBA) gene have been associated with the development of Parkinson's disease (PD). An induced pluripotent stem cell (iPSC) line was generated from a 60-year old patient diagnosed with PD and carrying a new mutation variant p.R301C in GBA. Using non-integrating Sendai virus-based technology, we utilized OCT3/4, SOX2, c-MYC and KLF4 transcription factors to reprogram skin fibroblasts into iPSCs. The generated iPSC line retained the mutation, displayed expression of common pluripotency markers, differentiated into the three germ layers, and exhibited normal karyotype. The iPSC line can be further used for studying PD pathogenesis., We thank AnnaKarin Olden, Anna Hammarberg and Marianne Juhlin, for their technical support. We are also thankful to the 'Cell Line and DNA Biobank from Patients affected by Genetic Diseases' (Istituto G. Gaslini, Genova, Italy) and the 'Parkinson Institute Biobank, members of the Telethon Network of Genetic Biobanks (http://biobanknetwork.telethon.it; project no. GTB12001) funded by Telethon Italy, for providing fibroblast samples. This work was supported by the Strategic Research Environment MultiPark at Lund University, the Swedish Research Council (grant 2015-03684 to LR), Finnish Cultural Foundation (grant 00161167 to YP), Portuguese Foundation for Science and Technology for the doctoral fellowship - PDE/BDE/113598/2015 to AM and IF Starting and Development Grant to LP and AJS (IF/01079/2014 and IF/00111/2013).

Spinal cord injury is extremely debilitating, both at physiological and psychological levels, changing completely the patient's lifestyle. The introduction of biomaterials has opened a new window to develop a therapeutic approach to induce regeneration after injury due to similarities with extracellular matrix. Particularly, hydrogels have the ability to support axonal growth and endogenous regeneration. Moreover, they can also act as potential matrixes in which to load and deliver therapeutic agents at injury site. In this review, we highlight some important characteristics to be considered when designing hydrogels as delivery systems (DS), such as rheology, mesh size, swelling, degradation, gelation temperature and surface charge. Additionally, affinity-based release systems, incorporation of nanoparticles, or ion-mediated interactions are also pondered. Overall, hydrogel DS aim to promote a sustained, controlled and prolonged release at injury site, allowing a targeted oriented action of the therapeutic agent that will be used., Graphical abstract Image 1

Research in the last decade strongly suggests that mesenchymal stem cell (MSC)-mediated therapeutic benefits are mainly due to their secretome, which has been proposed as a possible therapeutic tool for the treatment of Parkinson's disease (PD). Indeed, it has been shown that the MSC secretome increases neurogenesis and cell survival, and has numerous neuroprotective actions under different conditions. Additionally, using dynamic culturing conditions (through computer-controlled bioreactors) can further modulate the MSC secretome, thereby generating a more potent neurotrophic factor cocktail (i.e., conditioned medium). In this study, we have characterized the MSC secretome by proteomic-based analysis, investigating its therapeutic effects on the physiological recovery of a 6-hydroxidopamine (6-OHDA) PD rat model. For this purpose, we injected MSC secretome into the substantia nigra (SNc) and striatum (STR), characterizing the behavioral performance and determining histological parameters for injected animals versus untreated groups. We observed that the secretome potentiated the increase of dopaminergic neurons (i.e., tyrosine hydroxylase-positive cells) and neuronal terminals in the SNc and STR, respectively, thereby supporting the recovery observed in the Parkinsonian rats' motor performance outcomes (assessed by rotarod and staircase tests). Finally, proteomic characterization of the MSC secretome (through combined mass spectrometry analysis and Bioplex assays) revealed the presence of important neuroregulatory molecules, namely cystatin C, glia-derived nexin, galectin-1, pigment epithelium-derived factor, vascular endothelial growth factor, brain-derived neurotrophic factor, interleukin-6, and glial cell line-derived neurotrophic factor. Overall, we concluded that the use of human MSC secretome alone was able to partially revert the motor phenotype and the neuronal structure of 6-OHDA PD animals. This indicates that the human MSC secretome could represent a novel therapeutic for the treatment of PD., Portuguese Foundation for Science and Technology via a Ciência 2007 program and an FCT (Portuguese Foundation for Science and Technology) Investigator development grant (A.J.S.), predoctoral fellowships to F.G.T. (SFRH/69637/2010), and a fellowship to S.A. (SFRH/BD/81495/2011); a Canada Research Chair in Biomedical Engineering (L.A.B.) and a Schulich School of Engineering postdoctoral fellowship (K.M.P.), cofunded by Programa Operacional Regional do Norte (ON.2 – O Novo Norte), under Quadro de Referência Estratégico Nacional (QREN), through Fundo Europeu de Desenvolvimento Regional (FEDER), PEst-C/SAU/LA0001/2013-2014, cofunded by the Programa Operacional Factores de Competitividade, QREN, the European Union (FEDER), and by The National Mass Spectrometry Network under the contract REDE/1506/REM/2005, info:eu-repo/semantics/publishedVersion

Background: Massive rotator cuff tears (MRCTs) are usually chronic lesions with pronounced degenerative changes, where advanced fatty degeneration and atrophy can make the tear irreparable. Human mesenchymal stem cells (hMSCs) secrete a range of growth factors and vesicular systems, known as secretome, that mediates regenerative processes in tissues undergoing degeneration. Purpose: To study the effect of hMSC secretome on muscular degenerative changes and shoulder function on a rat MRCT model. Study Design: Controlled laboratory study. Methods: A bilateral 2-tendon (supraspinatus and infraspinatus) section was performed to create an MRCT in a rat model. Forty-four Wistar-Han rats were randomly assigned to 6 groups: control group (sham surgery), lesion control group (MRCT), and 4 treated-lesion groups according to the site and periodicity of hMSC secretome injection: single local injection, multiple local injections, single systemic injection, and multiple systemic injections. Forelimb function was analyzed with the staircase test. Atrophy and fatty degeneration of the muscle were evaluated at 8 and 16 weeks after injury. A proteomic analysis was conducted to identify the molecules present in the hMSC secretome that can be associated with muscular degeneration prevention. Results: When untreated for 8 weeks, the MRCT rats exhibited a significantly higher fat content (0.73% 0.19%) compared with rats treated with a single local injection (0.21% 0.04%; P < .01) or multiple systemic injections (0.25% +/- 0.10%; P < .05) of hMSC secretome. At 16 weeks after injury, a protective effect of the secretome in the multiple systemic injections (0.62% +/- 0.14%; P < .001), single local injection (0.76% +/- 0.17%; P < .001), and multiple local injections (1.35% +/- 0.21%; P < .05) was observed when compared with the untreated MRCT group (2.51% +/- 0.42%). Regarding muscle atrophy, 8 weeks after injury, only the single local injection group (0.0993% +/- 0.0036%) presented a significantly higher muscle mass than that of the untreated MRCT group (0.0794% +/- 0.0047%; P < .05). Finally, the proteomic analysis revealed the presence of important proteins with muscle regeneration, namely, pigment epithelium-derived factor and follistatin. Conclusion: The study data suggest that hMSC secretome effectively decreases the fatty degeneration and atrophy of the rotator cuff muscles. Clinical Relevance: We describe a new approach for decreasing the characteristic muscle degeneration associated with chronic rotator cuff tears. This strategy is particularly important for patients whose tendon healing after later surgical repair could be compromised by the progressing degenerative changes. In addition, both precise intramuscular local injection and multiple systemic secretome injections have been shown to be promising delivery forms for preventing muscle degeneration., This work is a result of the project (NORTE-01-0145-FEDER-000013), supported by Norte Portugal Regional Operational Programme (NORTE 2020) under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Cofinanciado pelo Programa Operacional Regional do Norte (ON. 2 SR&TD Integrated Program - NORTE-07-0124-FEDER-000021), ao abrigo do Quadro de Referencia Estrategico Nacional (QREN), atraves do Fundo Europeu de Desenvolvimento Regional (FEDER); Projeto Projeto Estrategico - LA 26 -2011-2012 and Projeto Estrategico - LA 26 - 2013-2014 cofinanciado por fundos nacionais, atraves da Fundacao para a Ciencia e a Tecnologia (PEst-C/SAU/LA0026/2011; PEst-C/SAU/LA0026/2013), e pelo Fundo Europeu de Desenvolvimento Regional (FEDER), atraves do COMPETE (FCOMP-01-0124-FEDER-022724; FCOMP-01-0124-FEDER-037298)., info:eu-repo/semantics/publishedVersion

BACKGROUND CONTEXT: Damage to the spinal cord can result in irreversible impairments or complete loss of motor, sensory, and autonomic functions. Riluzole and magnesium have been widely investigated as neuroprotective agents in animal models of spinal cord injury. As these drugs protect the injured spinal cord through different mechanisms, we aimed to investigate if their neuroprotective efficacy could be cumulative. PURPOSE: This study aimed to investigate the neuroprotective efficacy of combined administration of riluzole and magnesium chloride in a contusive model of thoracic spinal cord injury. STUDY DESIGN: An in vivo experiment was set using female Wistar Han rats that underwent a thoracic spinal cord contusion (T8) using a weight drop method. An hour after injury, animals were randomly distributed to receive (1) saline, (2) riluzole (2.50 mg/kg), (3) magnesium chloride (24.18 mg/kg) in a polyethylene glycol formulation, or (4) a combined treatment (riluzole and magnesium). Subsequent treatments were given in four intraperitoneal injections (spaced 12 hours apart). METHODS: The Basso, Beattie, and Bresnahan locomotor rating scale, an activity box test, and a swimming test were used to evaluate behavioral recovery over a 4-week period. Histologic analysis of the spinal cords was performed to measure the extent and volume of the lesion, axonal preservation, serotonergic and glutamatergic fiber sparing, motor neuron survival, and inflammation. RESULTS: Our results show that only the riluzole treatment significantly improved behavioral recovery up to 4 weeks after injury when compared with saline controls (6.2±1.8), with animals achieving weight-supported stepping (9.1±1.2). Riluzole also promoted tissue sparing with significant differences achieved from 200 to 600 m (caudally to the lesion epicenter), and reduced lesion volume, with animals presenting a significantly smaller lesion (3.23±0.26 mm3 ) when compared with the saline-treated group (4.74±0.80 mm3 ), representing a 32% decrease in lesion volume. Riluzole treatment induced significant axonal preservation, as well as serotonergic fiber sparing, caudally to the injury epicenter. CONCLUSIONS: Our results suggest that the combined treatment, although simultaneously targeting two excitotoxic-related mechanisms, did not further improve behavioral and histologic outcome when compared with riluzole given alone., Prémios Santa Casa Neurociências – Prize Melo e Castro for Spinal Cord Injury Research; Portuguese Foundation for Science and Technology (Post-Doctoral fellowship – SFRH/ BPD/97701/2013 – to NA Silva; IF Development Grant to AJ Salgado); This article is a result of the project (NORTE01-0145-FEDER-000013), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); Cofinanciado pelo Programa Operacional Regional do Norte (ON.2 SR&TD Integrated Program – NORTE-07-0124-FEDER-000021), ao abrigo do Quadro de Referência Estratégico Nacional (QREN), através do Fundo Europeu de Desenvolvimento Regional (FEDER); Projeto Estratégico – LA 26 – 2011–2012 and Projeto Estratégico – LA 26 – 2013–2014 cofinanciado por fundos nacionais, através da Fundação para a Ciência e a Tecnologia (PEst-C/SAU/LA0026/2011; PEst-C/SAU/ LA0026/2013), e pelo Fundo Europeu de Desenvolvimento Regional (FEDER), através do COMPETE (FCOMP-01- 0124-FEDER-022724; FCOMP-01-0124-FEDER-037298).

Spinal cord injury is a devastating condition of the central nervous system, in which traditional treatments are largely ineffective due to the complex nature of the injured tissue. Therefore, biomaterial-based systems have been developed as possible alternative strategies to repair the damaged tissue. In the present study, we aimed to design bioactive agent loaded scaffolds composed of two layers with distinct physical properties to improve tissue regeneration. An electrospun layer with aligned nanofibers was made of collagen (Col) Type-I, poly(lactide-co-glycolide) (PLGA) and laminin to promote cell attachment of mesenchymal-like stem cells towards the direction of fibers, while a Col-based second layer was fabricated by plastic compression to act as a releasing system for NT-3 and chondroitinase ABC, so that axonal growth could be stimulated. Results showed that a source of mesenchymal stem cell (MSC)-like cells, adipose tissue-derived stem cells cultured on the fibrous layer of the matrices were able to adhere and proliferate, where the aligned fibers promoted the cell growth in an organized way. Furthermore, the bilayered matrices also promoted dorsal root ganglion neurite outgrowth. The bilayered matrice with Col/PLGA + laminin top layer appears to promote higher neurite growth. Collectively, the designed constructs show promising structural properties and biological performance for being employed as a scaffold for engineering the spinal cord tissue.

Mechanisms underlying affective and cognitive deficits in Parkinson's disease (PD) remain less studied than motor symptoms. Nucleus accumbens (NAc) is affected in PD and due to its well-known involvement in motivation is an interesting target in this context. Furthermore, PD is frequently asymmetrical, with side-specific deficits aligning with evidences of accumbal laterality. We therefore used a 6-hydroxydopamine (6-OHDA) model to study the role of left and right NAc dopamine depletion in a battery of behavioral tasks. 2 months old male rats were used in all experiments. Habitual-based and goal-directed decision-making, impulsivity, anxiety- and depressive-like behavior and motor performance were tested 3 weeks after left (6-OHDA L) or right (6-OHDA R) NAc lesion was induced. Upon contingency degradation, 6-OHDA R decrease their lever press rate less than Sham and 6-OHDA L, indicating an impairment in the shift from habit-based to goal-directed strategies. On the other hand, 6-OHDA L lesions lead to increased rates of premature responding when delays where increased in the variable delay-to-signal test. Importantly, in both paradigms task acquisition was similar between groups. In the same line we found no differences in the amount of sugared pellets eaten when freely available as well as in both general and fine motor behaviors. In conclusion, left and right NAc play distinct roles in the contingency degradation and impulsivity. More studies are needed to understand the mechanisms behind this functional lateralization and its implications for PD patients.

Cell transplantation using Mesenchymal stem cell (MSC) secretome have recently been presented as a possible free-based therapy for CNS related disorders. MSC secretome is rich in several bio-factors that act synergically towards the repair of damaged tissues, thus making it an ideal candidate for regenerative applications. Great effort is currently being made to map the molecules that compose the MSC secretome. Previous proteomic characterization of the secretome (in the form of conditioned media - CM) of MSCs derived from adipose tissue (ASC), bone-marrow (BMSC) and umbilical cord (HUCPVC) was performed by our group, where proteins relevant for neuroprotection, neurogenic, neurodifferentiation, axon guidance and growth functions were identified. Moreover, we have found significant differences among the expression of several molecules, which may indicate that their therapeutic outcome might be distinct. Having this in mind, in the present study, the neuroregulatory potential of ASC, BMSC and HUCPVC CM in promoting neurodifferentiation and axonal outgrowth was tested in vitro, using human telencephalon neuroprogenitor cells and dorsal root ganglion explants, respectively. The CM from the three MSC populations induced neuronal differentiation from human neural progenitor cells, as well as neurite outgrowth from dorsal root ganglion explants. Moreover, all the MSC populations promoted the same extent of neurodifferentiation, while ASC CM demonstrated higher potential in promoting axonal growth., The authors acknowledge the financial support by Premios Santa Casa Neurociencias - Prize Melo e Castro for Spinal Cord ^ Injury Research (MC-17-2013 and MC-04-2017); Portuguese Foundation for Science and Technology (Doctoral fellowships PDE/ BDE/113596/2015 and SFRH/BD/120124/2016 to R.C Assunçao Silva ~ and B. Mendes-Pinheiro, respectively; Post-doctoral fellowhip to F.G. Teixeira and Patrícia Patrício - SFRH/BPD/118408/2016 and SFRH/BPD/116249/2016; IF Starting Grant to L. Pinto and IF Development Grant to A. J. Salgado); Canada Research Chair in Biomedical Engineering (LAB). This work is funded by national funds through FCT under the scope of grante reference TUBITAK/0007/ 2014. This article has been developed under the scope of the project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology, under the scope of the project POCI-01-0145-FEDER-007038. HUCPVCs and ASCs were kindly provided by Prof. John E. Davies (University of Toronto, Canada) and Prof. Jeff Gimble (LaCell Inc, USA)., info:eu-repo/semantics/publishedVersion

An induced pluripotent stem cell (iPSC) line was generated from a 36-year-old patient with sporadic Parkinson's disease (PD). Skin fibroblasts were reprogrammed using the non-integrating Sendai virus technology to deliver OCT3/4, SOX2, c-MYC and KLF4 factors. The generated cell line (CSC-43) exhibits expression of common pluripotency markers, in vitro differentiation into three germ layers and normal karyotype. This iPSC line can be used to study the mechanisms underlying the development of PD., ‘Cell Line and DNA Biobank from Patients affected by Genetic Diseases’ (Istituto G. Gaslini, Genova, Italy) and the Parkinson Institute Biobank, members of the Telethon Network of Genetic Biobanks (http://biobanknetwork.telethon.it; project no. GTB12001) funded by Telethon Italy, for providing fibroblasts samples. This work was supported by the Strategic Research Environment MultiPark at Lund University, the strong research environment BAGADILICO (grant 349-2007-8626), the Swedish Parkinson Foundation (Parkinsonfonden, grant 889/16), the Swedish Research Council (grant 2015-03684 to LR) and Finnish Cultural Foundation (grant 00161167 to YP). We also acknowledge the Portuguese Foundation for Science and Technology, info:eu-repo/semantics/publishedVersion

Background: Glioblastoma (GBM), the most malignant primary brain tumor, leads to poor and unpredictable clinical outcomes. Recent studies showed the tumor microenvironment has a critical role in regulating tumor growth by establishing a complex network of interactions with tumor cells. In this context, we investigated how GBM cells modulate resident glial cells, particularly their paracrine activity, and how this modulation can influence back on the malignant phenotype of GBM cells. Methods: Conditioned media (CM) of primary mouse glial cultures unexposed (unprimed) or exposed (primed) to the secretome of GL261 GBM cells were analyzed by proteomic analysis. Additionally, these CM were used in GBM cells to evaluate their impact in glioma cell viability, migration capacity and activation of tumor-related intracellular pathways. Results: The proteomic analysis revealed that the pre-exposure of glial cells to CM from GBM cells led to the upregulation of several proteins related to inflammatory response, cell adhesion and extracellular structure organization within the secretome of primed glial cells. At the functional levels, CM derived from unprimed glial cells favored an increase in GBM cell migration capacity, while CM from primed glial cells promoted cells viability. These effects on GBM cells were accompanied by activation of particular intracellular cancer-related pathways, mainly the MAPK/ERK pathway, which is a known regulator of cell proliferation. Conclusions: Together, our results suggest that glial cells can impact on the pathophysiology of GBM tumors, and that the secretome of GBM cells is able to modulate the secretome of neighboring glial cells, in a way that regulates the "go-or-grow" phenotypic switch of GBM cells., Fundação para a Ciência e Tecnologia (IF/00601/2012 to B.M.C.; IF/00111 to A.J.S; SFRH/BD/52287/2013 to A.I.O.; SFRH/BD/81495/2011 to S.I.A.; SFRH/BD/88121/2012 to J.V.C.; projects PTDC/SAU-GMG/113795/2009 to B.M.C.; PTDC/NEU-NMC/0205/2012, PTDC/NEU-SCC/7051/2014, PEst-C/SAU/LA0001/2013–2014 and UID/NEU/04539/2013 to B.M.), Liga Portuguesa Contra o Cancro (B.M.C.), Fundação Calouste Gulbenkian (B.M.C.) and Inter-University Doctoral Programme in Ageing and Chronic Disease (PhDOC; to A.I.O.). Project co-financed by Programa Operacional Regional do Norte (ON.2—O Novo Norte), Quadro de Referência Estratégico Nacional (QREN), Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Operacional Factores de Competitividade (COMPETE), and by The National Mass Spectrometry Network (RNEM) under the contract REDE/1506/REM/2005, info:eu-repo/semantics/publishedVersion

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons and/or loss od neuronal projections, in several dopaminergic networks. Current treatments for idiopathic PD rely mainly on the use of pharmacologic agents to improve motor symptomatology of PD patients. Nevertheless, so far PD remains an incurable disease. Therefore, it is of utmost importance to establish new therapeutic strategies for PD treatment. Over the last 20 years, several molecular, gene and cell/stem-cell therapeutic approaches have been developed with the aim of counteracting or retarding PD progression. The scope of this review is to provide an overview of PD related therapies and major breakthroughs achieved within this field. In order to do so, this review will start by focusing on PD characterization and current treatment options covering thereafter molecular, gene and cell/stem cell-based therapies that are currently being studied in animal models of PD or have recently been tested in clinical trials. Among stem cell-based therapies, those using MSCs as possible disease modifying agents for PD therapy and, specifically, the MSCs secretome contribution to meet the clinical challenge of counteracting or retarding PD progression, will be more deeply explored., Portuguese Foundation for Science and Technology (FCT) for the PhD fellowship attributed to A.O. Pires (Reference: SFRH/BD/33900/2009) and the IF development grant to A.J. Salgado (Reference: IF/00111/2013). Project NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). Funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038, info:eu-repo/semantics/publishedVersion

Traumatic spinal cord injury (SCI) causes dramatic disability and dysfunction in the motor, sensory and autonomic systems. The severe inflammatory reaction that occurs after SCI is strongly associated with further tissue damage. As such, immunomodulatory strategies have been developed, aimed at reducing inflammation, but also at shaping the immune response in order to protect, repair and promote regeneration of spared neural tissue. One of those promising strategies is the intraspinal administration of the cytokine interleukin-4 (IL-4) that was shown to promote a phenotype on specific immune cells associated with neuroprotection and repair. In this work, we evaluated if a systemic delivery of IL-4 for a 7-days period was also capable of promoting neuroprotection after SCI by analyzing different neural cells populations and motor recovery. IL-4 treatment promoted an elevation of the anti-inflammatory cytokine IL-10 in the serum both at 24 h and 7 days after injury. Locally, treatment with IL-4 led to a reduction on cells expressing markers associated with inflammation, CD11b/c and iNOS. Importantly, IL-4 treatment increased the neuronal markers beta III-tubulin and NeuN, and the oligodendrocyte marker O4, suggesting a neuroprotective effect. Moreover, 100% of the animals treated with IL-4 were able to recover weight support against only 33% of saline treated animals. Overall, these results show that systemic administration of IL-4 positively impacts different aspects of spinal cord injury, creating a more favorable environment for recovery to take place., Prémios Santa Casa Neurociências—Prize Melo e Castro for Spinal Cord Injury Research; Portuguese Foundation for Science and Technology (Financiado no âmbito do Projecto 3599—Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de Redes Temáticas (3599-PPCDT), project: PTDC/DTP-FTO/5109/2014; Post-Doctoral fellowship—SFRH/BPD/97701/2013—to N.A. Silva; IF Development Grant to A. J. Salgado; fellowships—PD/BDE/127836/2016—to R. Lima; SFRH/BD/103075/2014—to E. D. Gomes; PDE/BDE/113596/2015—to R. C. Assunção-Silva; SFRH/BD/88825/2012—to M. Morais); This article is a result of the project (NORTE-01-0145-FEDER-000013), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER); This work has been funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038, info:eu-repo/semantics/publishedVersion

The loss of dopaminergic neurons (DAn) and reduced dopamine (DA) production underlies the reasoning behind the gold standard treatment for Parkinson's disease (PD) using levodopa (L-DOPA). Recently licensed by the European Medicine Agency (EMA) and US Food and Drug Administration (FDA), safinamide [a monoamine oxidase B (MOA-B) inhibitor] is an alternative to L-DOPA; as we discuss here, it enhances dopaminergic transmission with decreased secondary effects compared with L-DOPA. In addition, nondopaminergic actions (neuroprotective effects) have been reported, with safinamide inhibiting glutamate release and sodium/calcium channels, reducing the excitotoxic input to dopaminergic neuronal death. Effects of safinamide have been correlated with the amelioration of non-motor symptoms (NMS), although these remain under discussion. Overall, safinamide can be considered to have potential antidyskinetic and neuroprotective effects and future trials and/or studies should be performed to provide further evidence for its potential as an anti-PD drug., The authors acknowledge funding from the Portuguese Foundation for Science and Technology (IF development grant IF/ 00111/2013 to A.J.S.) and a postdoctoral fellowship to F.G.T. (SFRH/BPD/118408/2016). This work was funded by FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by national funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-007038. This article has also been developed under the scope of the project NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER).

Importance The surgical outcomes of massive rotator cuff tears (MRCTs) repair are poorly reported in the scientific literature. Objective This study aimed to evaluate the reported outcomes of open or arthroscopic repair of MRCTs. Evidence review We comprehensively searched the Medline, Scopus, Cochrane Database of Systematic Reviews and CENTRAL databases up to January 2017. We included studies with a prospective design assessing the outcomes of open or arthroscopic repair of MRCTs, with a minimum of 1 year of follow-up. We excluded studies in which subgrouping of massive tears was not possible. We assessed the methodological quality of the studies using the Coleman methodology score. Findings We included 12 studies (comprising 990 patients, 511 of whom had an MRCT): eight reported the arthroscopic rotator cuff repair outcomes, two reported open repair and the other two reported the outcomes of both techniques. The mean follow-up time was 57 months (range 12–108). A quantitative synthesis of the arthroscopic rotator cuff repair results showed clinical improvements in the Constant and American Shoulder and Elbow Surgeons scores from preoperatively to postoperatively. Comparing the arthroscopic and open repair procedures, we observed similar pooled weighted means for the Constant, University of California, Los Angeles and American Shoulder and Elbow Surgeons scores at 26–56 months of follow-up. Conclusions and relevance Both arthroscopic and open repair produced similar and improved postoperative outcomes to those preoperatively. MRCT repair requires further research and better reporting to obtain stronger conclusions. Level of evidence Level II, systematic review and meta-analysis., info:eu-repo/semantics/publishedVersion

Mesenchymal stem cells (MSCs) have been used for cell-based therapies in regenerative medicine, with increasing importance in central and peripheral nervous system repair. However, MSCs grafting present disadvantages, such as, a high number of cells required for transplantation and low survival rate when transplanted into the central nervous system (CNS). In line with this, MSCs secretome which present on its composition a wide range of molecules (neurotrophins, cytokines) and microvesicles, can be a solution to surpass these problems. However, the effect of MSCs secretome in axonal elongation is poorly understood. In this study, we demonstrate that application of MSCs secretome to both rat cortical and hippocampal neurons induces an increase in axonal length. In addition, we show that this growth effect is axonal intrinsic with no contribution from the cell body. To further understand which are the molecules required for secretome-induced axonal outgrowth effect, we depleted brain-derived neurotrophic factor (BDNF) from the secretome. Our results show that in the absence of BDNF, secretome-induced axonal elongation effect is lost and that axons present a reduced axonal growth rate. Altogether, our results demonstrate that MSCs secretome is able to promote axonal outgrowth in CNS neurons and this effect is mediated by BDNF.

BACKGROUND: Massive rotator cuff tears (MRCTs) represent a major clinical concern, especially when degeneration and chronicity are involved, which highly compromise healing capacity. PURPOSE: To study the effect of the secretome of mesenchymal stem cells (MSCs) on tendon cells (TCs) followed by the combination of these activated TCs with an electrospun keratin-based scaffold to develop a tissue engineering strategy to improve tendon-bone interface (TBi) healing in a chronic MRCT rat model. STUDY DESIGN: Controlled laboratory study. METHODS: Human TCs (hTCs) cultured with the human MSCs (hMSCs) secretome (as conditioned media [CM]) were combined with keratin electrospun scaffolds and further implanted in a chronic MRCT rat model. Wistar-Han rats (N = 15) were randomly assigned to 1 of 3 groups: untreated lesion (MRCT group, n = 5), lesion treated with a scaffold only (scaffold-only group, n = 5), and lesion treated with a scaffold seeded with hTCs preconditioned with hMSCs-CM (STC_hMSC_CM group, n = 5). After sacrifice, 16 weeks after surgery, the rotator cuff TBi was harvested for histological analysis and biomechanical testing. RESULTS: The hMSCs secretome increased hTCs viability and density in vitro. In vivo, a significant improvement of the tendon maturing score was observed in the STC_hMSC_CM group (mean ± standard error of the mean, 15.6 ± 1.08) compared with the MRCT group (11.0 ± 1.38; P < .05). Biomechanical tests revealed a significant increase in the total elongation to rupture (STC_hMSC_CM, 11.99 ± 3.30 mm; scaffold-only, 9.89 ± 3.47 mm; MRCT, 5.86 ± 3.16 mm; P < .05) as well as a lower stiffness (STC_hMSC_CM, 6.25 ± 1.74 N/mm; scaffold-only, 6.72 ± 1.28 N/mm; MRCT, 11.54 ± 2.99 N/mm; P < .01). CONCLUSION: The results demonstrated that hMSCs-CM increased hTCs viability and density in vitro. Clear benefits also were observed when these primed cells were integrated into a tissue engineering strategy with an electrospun keratin scaffold, as evidenced by improved histological and biomechanical properties for the STC_hMSC_CM group compared with the MRCT group. CLINICAL RELEVANCE: This work supports further investigation into the use of MSC secretome for priming TCs toward a more differentiated phenotype, and it promotes the tissue engineering strategy as a promising modality to help improve treatment outcomes for chronic MRCTs., info:eu-repo/semantics/publishedVersion