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Purpose: This study investigated the influence of cleanroom conditions on the discard rates of donor corneas in a German university eye bank., Methods: Discard rates were analysed from 2017 to 2020 at the LIONS Cornea Bank at Saarland University Medical Center. 1941 corneas from 971 donors were included. 1262 corneas (65.1%) were stored in a class D cleanroom from 2017 to 2019 and processed in a cleanroom class A sterile bank (group 1). 679 corneas (34.9%) were continuously stored in a class B cleanroom and processed in a class A cleanroom safety cabinet in the same room from 2019 to 2020 (group 2). The target parameter of this work was the number of contamination-related discards. Although they cannot be influenced by the spatial conditions, the discards due to insufficient endothelial quality, serology, contraindications, scars and technical causes were also recorded. Statistical analysis was performed using SPSS and various testing procedures., Results: In group 1, significantly more corneas were discarded due to positive serology (6.9%|3.8%, p = 0.020). There was no significant change between both groups for either contamination or the other reasons for discard., Conclusion: Optimization of hygiene standards from cleanroom class D to B did not reduce contamination. Serology, endothelial quality, medical contraindications and the presence of scars cannot be influenced by cleanroom conditions., (© 2023 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.)

Organoids hold inestimable therapeutic potential in regenerative medicine and are increasingly serving as an in vitro research platform. Still, their expanding applications are critically restricted by the canonical culture matrix and system. Synthesis of a suitable bioink of bioactivity, biosecurity, tunable stiffness, and printability to replace conventional matrices and fabricate customized culture systems remains challenging. Here, we envisaged a novel bioink formulation based on decellularized extracellular matrix (dECM) from porcine small intestinal submucosa for organoids bioprinting, which provides intestinal stem cells (ISCs) with niche-specific ECM content and biomimetic microstructure. Intestinal organoids cultured in the fabricated bioink exhibited robust generation as well as a distinct differentiation pattern and transcriptomic signature. This bioink established a new co-culture system able to study interaction between epithelial homeostasis and submucosal cells and promote organoids maturation after transplantation into the mesentery of immune-deficient NODSCID-gamma (NSG) mice. In summary, the development of such photoresponsive bioink has the potential to replace tumor-derived Matrigel and facilitate the application of organoids in translational medicine and disease modeling. [ABSTRACT FROM AUTHOR]

In this study, needleless electrospinning technology was used to obtain flexirubin (F)‐loaded polyvinyl alcohol (PVA)_kefiran (KF)/polycaprolactone (PCL) electrospun nanofibers. The SEM images of PVA_KF_ F and PCL_F nanofibers displayed beadless morphology with average diameters of 211.90 ± 96.08 and 1610.71 ± 996.68 nm, respectively. FTIR‐ATR analysis revealed increased intensity at specific wavelengths, after pigment incorporation. The high porosity exhibited by each layer and the mechanical properties of the double‐layered nanofibrous material remained unaffected after flexirubin‐type pigment incorporation. In addition, PVA_KF_F/PCL_F nanofibers showed antioxidant activity of 41.03 ± 0.29%, evaluated by the scavenging of the ABTS radical as well as the ability to reduce enzymatic browning of apple slices. Thus, we believe that the fabricated PVA_KF_F/PCL_F double‐layered material can be considered for application in active food packaging systems. [ABSTRACT FROM AUTHOR]

Damaged complex modular organs repair is a current clinical challenge in which one of the primary goals is to keep their biological response. An interesting case of study it is the porcine esophagus since it is a tubular muscular tissue selected as raw material for tissue engineering. The design of esophageal constructs can draw on properties of the processed homologous extracellular matrix (ECM). In this work, we report the decellularization of multilayered esophagus tissue from 1‐, 21‐ and 45‐days old piglets through the combination of reversible alkaline swelling and detergent perfusion. The bioscaffolds were characterized in terms of their residual composition and tensile mechanical properties. The biological response to esophageal submucosal derived bioscaffolds modified with ECM gel containing epoxyeicosatrienoic acids (EETs) was then evaluated. Results suggest that the composition (laminin, fibronectin, and sulphated glycosaminoglycans/sGAG) depends on the donor age: a better efficiency of the decellularization process combined with a higher retention of sGAG and fibronectin is observed in piglet esophageal scaffolds. The heterogeneity of this esophageal ECM is maintained, which implied the preservation of anisotropic tensile properties. Coating of bioscaffolds with ECM gel is suitable for carrying esophageal epithelial cells and EETs. Bioactivity of EETs‐ECM gel modified esophageal submucosal bioscaffolds is observed to promote neovascularization and antiinflammatory after rabbit full‐thickness esophageal defect replacement. [ABSTRACT FROM AUTHOR]

Circadian rhythms are characterized as oscillations that fluctuate based on a 24 h cycle and are responsible for regulation of physiological functions. While the internal clock synchronizes gene expression using external cues like light, a similar synchronization can be induced in vitro by incubating the cells with an increased percentage of serum followed by its rapid removal. Previous studies have suggested that synchronization of HepG2 cell line induced the rhythmic expression of drug‐metabolizing enzymes (DME) most specifically the cytochrome P450 enzymes. However, there is a lack of evidence demonstrating the influence of three‐dimensional microenvironment on the rhythmicity of these genes. To understand this interplay, gene expression of the circadian machinery and CYP450s were compared using the model human hepatocarcinoma cell line, HepG2. Upon serum shock synchronization, gene and protein expression of core clock regulators was assessed and rhythmic expression of these genes was demonstrated. Further insight into the interrelations between various gene pairs was obtained using statistical analysis. Using RNA sequencing, an in‐depth understanding of the widespread effects of circadian regulation on genes involved in metabolic processes in the liver was obtained. This study aids in the better understanding of chronopharmacokinetic events in humans using physiologically relevant 3D culture systems. [ABSTRACT FROM AUTHOR]

Engineered replacement materials have tremendous potential for vascular applications where over 400,000 damaged and diseased blood vessels are replaced annually in the United States alone. Unlike large diameter blood vessels, which are effectively replaced by synthetic materials, prosthetic small‐diameter vessels are prone to early failure, restenosis, and reintervention surgery. We investigated the differential response of varying 0%–6% sodium dodecyl sulfate and sodium deoxycholate anionic detergent concentrations after 24 and 72 h in the presence of DNase using biochemical, histological, and biaxial mechanical analyses to optimize the decellularization process for xenogeneic vascular tissue sources, specifically the porcine internal thoracic artery (ITA). Detergent concentrations greater than 1% were successful at removing cytoplasmic and cell surface proteins but not DNA content after 24 h. A progressive increase in porosity and decrease in glycosaminoglycan (GAG) content was observed with detergent concentration. Augmented porosity was likely due to the removal of both cells and GAGs and could influence recellularization strategies. The treatment duration on the other hand, significantly improved decellularization by reducing DNA content to trace amounts after 72 h. Prolonged treatment times reduced laminin content and influenced the vessel's mechanical behavior in terms of altered circumferential stress and stretch while further increasing porosity. Collectively, DNase with 1% detergent for 72 h provided an effective and efficient decellularization strategy to be employed in the preparation of porcine ITAs as bypass graft scaffolding materials with minor biomechanical and histological penalties. [ABSTRACT FROM AUTHOR]

Aim: To investigate the vascularization capacity of a decellularized dental pulp matrix (DDP) of bovine origin seeded with human dental pulp stem cells (hDPSCs) in vitro and to present preliminary in vivo findings. Methodology: Bovine dental pulps were decellularized and then analysed using histological staining and DNA quantification. The resultant DDPs were characterized using immunohistochemical staining for the retention of vascular endothelial growth factor A (VEGF‐A) and fibroblast growth factor 2 (FGF‐2). Furthermore, DDPs were recellularized with hDPSCs and analysed histologically. The expression of markers involved in angiogenesis by hDPSCs colonizing the DDPs was assessed in vitro. A preliminary in vivo study was then conducted in which hDPSCs‐seeded and unseeded DDPs were inserted in debrided human premolars root slices and implanted subcutaneously in immunodeficient mice. Samples were retrieved after 30 days and analysed using histological and immunohistochemical staining. The independent samples t‐test, analysis of variance and a Kruskal–Wallis test were used to analyse the quantitative data statistically depending on the group numbers and normality of data distribution. The difference between the groups was considered significant when the P‐value was less than 0.05. Results: Acellular dental pulp matrices were generated following bovine dental pulp decellularization. Evaluation of the developed DDPs revealed a significant DNA reduction (P < 0.0001) with preservation of the native histoarchitecture and vasculature and retention of VEGF‐A and FGF‐2. Upon recellularization of the DDPs with hDPSCs, the in vitro analyses revealed cell engraftment with progressive repopulation of DDPs' matrices and vasculature and with enhanced expression of markers involved in angiogenesis. In vivo implantation of root slices with hDPSCs‐seeded DDPs revealed apparent vascularization enhancement as compared to the unseeded DDP group (P < 0.0001). Conclusions: The developed decellularized dental pulp matrix had pro‐angiogenic properties characterized by the retention of native vasculature and angiogenic growth factors. Seeding of hDPSCs into the DDP led to progressive repopulation of the vasculature, enhanced expression of markers involved in angiogenesis in hDPSCs and improved in vivo vascularization capacity. The se suggest that a combination of DDP and hDPSCs have the potential to provide a promising vascularization promoting strategy for dental pulp regeneration. [ABSTRACT FROM AUTHOR]

Decellularized xenografts are an inherent component of regenerative medicine. Their preserved structure, mechanical integrity and biofunctional composition have well established them in reparative medicine for a diverse range of clinical indications. Nonetheless, their performance is highly influenced by their source (ie species, age, tissue) and processing (ie decellularization, crosslinking, sterilization and preservation), which govern their final characteristics and determine their success or failure for a specific clinical target. In this review, we provide an overview of the different sources and processing methods used in decellularized xenografts fabrication and discuss their effect on the clinical performance of commercially available decellularized xenografts. [ABSTRACT FROM AUTHOR]

To expand the application of perfusion decellularization beyond isolated single organs, we used the native vasculature of adult and neonatal rats to systemically decellularize the organs of a whole animal in situ. Acellular scaffolds were generated from kidney, liver, lower limb, heart‐lung system, and a whole animal body, demonstrating that perfusion decellularization technology is applicable to any perfusable tissue, independent of age. Biochemical and histological analyses demonstrated that organs and organ systems (heart‐lung pair and lower limb) were successfully decellularized, retaining their extracellular matrix (ECM) structure and organ‐specific composition, as evidenced by differences in organ‐specific scaffold stiffness. Altogether, we demonstrated that organs, organ systems and whole animal bodies can be perfusion decellularized while retaining ECM components and biomechanics. [ABSTRACT FROM AUTHOR]

Acellular scaffolds from decellularized donor organs are showing promising clinical results in tissue and organ repair and regeneration. A successful decellularization process is determined by (a) its capability to decellularize complete organs of large animals, (b) retention of the extracellular matrix (ECM) structures and morphologies, and (c) minimal loss of ECM proteins. In this study, porcine esophagi were perfused in full thickness with 0.25% w/v sodium dodecyl sulfate at perfusion rates 0.1–0.2 ml/min for up to 5 days. Decellularized tissues were characterized for their residual DNA, histological staining for their matrix structures, immunohistochemical staining for collagen type IV and laminin, and scanning electron microscopy for structural integrity. Our results showed that full thickness esophageal tissues treated using the horizontal perfusion setup were decellularized with good structural and biochemical integrity in the ECM. Residual DNA content in decellularized tissues was found to be 36 ± 12 ng/mg of tissues (n = 6) which was significantly lower than that of native tissues (p =.00022). Our study showed that the organ must be decellularized in full thickness and perfusion pressure must be controlled to minimize radial expansion. These factors were found to be critical in preserving the folded mucosa in the decellularized tissues. [ABSTRACT FROM AUTHOR]

Background: We evaluated the outcome of esophageal reconstructions using tissue‐engineered scaffolds. Method: Partial esophageal defects were reconstructed with the following scaffolds; animals were grouped (n = 7 per group) as follows: (a) normal rats; (b) rats implanted with three‐dimensional printing (3DP) polycaprolactone (PCL) scaffolds; (c) with human adipose‐derived mesenchymal stem cell (ADSC)‐seeded 3DP PCL scaffolds; (d) with polyurethane (PU)‐nanofiber(Nf) scaffolds; and (e) with ADSC‐seeded PU‐Nf scaffolds. Results: The esophageal defects were successfully repaired; however, muscle regeneration was greater in the 3DP PCL + ADSC groups than in the PU‐Nf + ADSC groups (P <.001). Regeneration of the epithelium was greater in PU‐Nf and PU‐Nf + ADSC groups than in the 3DP PCL and 3DP PCL + ADSC groups (P <.001). Conclusion: A tendency for more re‐epithelization was observed with the PU‐Nf scaffolds, while more muscle regeneration was achieved with the 3DP PCL scaffolds. [ABSTRACT FROM AUTHOR]

The development of pancreatic extracellular matrices enriched with insulin‐secreting β‐cells is a promising tissue engineering approach to treat type 1 diabetes. However, its long‐term therapeutic efficacy is restricted by the defensive mechanism of host immune response and the lack of developed vascularization as appropriate after transplantation. Platelet‐rich plasma (PRP), as an autologous platelet concentrate, contains a large number of active factors that are essential for the cell viability, vascularization, and immune regulation. In this study, we have incorporated pancreatic extracellular matrix (PEM) with PRP to develop a three‐dimensional (3D) injectable PEM‐PRP hydrogel to coculture and transplant rat insulinoma cells (INS‐1) and human umbilical vein endothelial cells (HUVECs). Results from this study demonstrated that PEM‐PRP hydrogel mimicked the biochemical compositions of native extracellular matrices, and possessed the enhanced elastic modulus and resistance to enzymatic degradation that enabled biomaterials to maintain its volume and slowly degrade. Additionally, PEM‐PRP hydrogel could release growth factors in a sustained manner. In vitro, PEM‐PRP hydrogel significantly promoted the viability, insulin‐secreting function, and insulin gene expression of gel encapsulated INS‐1 cells. Moreover, HUVECs encapsulated in PEM‐PRP hydrogel were found to constitute many lumen‐like structures and exhibited high expression of proangiogenic genes. In vivo transplantation of PEM‐PRP hydrogel encapsulated with INS‐1 cells and HUVECs improved the viability of INS‐1 cells, promoted vascularization, inhibited the host inflammatory response, and reversed hyperglycemia of diabetic rats. Our study suggests that the PEM‐PRP hydrogel offers excellent biocompatibility and proangiogenic property, and may serve as an effective biomaterial platform to maintain the long‐term survival and function of insulin‐secreting β cells. [ABSTRACT FROM AUTHOR]

Perfusion decellularization has been proposed as a promising method for generating nonimmunogenic organs from allogeneic or xenogeneic donors. Several imaging modalities have been used to assess vascular integrity in bioengineered organs with no consistency in the methodology used. Here, we studied the use of fluoroscopic angiography performed under controlled flow conditions for vascular integrity assessment in bioengineered kidneys. Porcine kidneys underwent ex vivo angiography before and after perfusion decellularization. Arterial and venous patencies were defined as visualization of contrast medium (CM) in distal capillaries and renal vein, respectively. Changes in vascular permeability were visualized and quantified. No differences in patency were detected in decellularized kidneys compared with native kidneys. However, focal parenchymal opacities and significant delay in CM clearance were detected in decellularized kidneys, indicating increased permeability. Biopsy‐induced leakage was visualized in both groups, with digital subtraction angiography revealing minimal CM leakage earlier than nonsubtracted fluoroscopy. In summary, quantitative assessment of vascular permeability should be coupled with patency when studying the effect of perfusion decellularization on kidney vasculature. Flow‐controlled angiography should be considered as the method of choice for vascular assessment in bioengineered kidneys. Adopting this methodology for organs premodified ex vivo under normothermic machine perfusion settings is also suggested. [ABSTRACT FROM AUTHOR]

Based on Organ Procurement and Transplantation Network data as of December 2019, more than 113 000 patients require an organ transplantation, yet, over the course of this past year, only 36 000 patients received a transplant. This discrepancy between those that need a donor organ and those that receive one remains one of medicine's biggest challenges. Multiple solutions, both biologic and artificial, have been proposed to mitigate this difference. One of the most promising approaches to generate bioartificial organs for transplantation involves re‐seeding decellularized scaffolds with appropriate cells. Decellularization involves physical, chemical, or biological methods that typically require intimate contact of various decellularization solutions with each cell. Consequently, conventional submersion decellularization has been limited to simple tissues such as heart valves. The invention of perfusion decellularization was a breakthrough that allowed the generation of tissue‐engineered scaffolds from tissues with higher structural organization and entire organs. Such scaffolds are composed of a myriad of extracellular matrix (ECM) components that include collagen, elastin, proteoglycans, and glycoproteins. Together, these components allow the scaffolds to fulfill specialized functions, such as structural functions as well as biological functions including the regulation of cellular processes and extracellular molecules. These specialized functions of decellularized scaffolds can increasingly be harnessed for applications in tissue engineering. [ABSTRACT FROM AUTHOR]

More and more scholars regard the lesion of liver cirrhosis as a series of progressive clinical stages. Besides, liver cirrhosis is a late stage of scarring (fibrosis) of the liver, and has long been a common cause of death for the global adult population, thus, the treatment of liver cirrhosis is a key point investigated in the biomedical field. Here, we propose a novel hypothesis; if decellularized liver matrix (DLM) is possible injected into the injurant‐induced fiberized liver via the hepatic portal vein to thoroughly repair the liver, it may be an effective therapeutic method for liver fibrosis or even liver cirrhosis. This study mixed rat DLM with gelatin‐hydroxyphenylpropionic acid (Glt‐HPA) to form a three‐dimensional structure to simulate the in vivo liver environment, and cultured the primary rat hepatocytes in it. Afterward, the hepatocytes were treated using D‐galactosamine (GaIN), CHCl3, and CCl4‐containing medium to simulate the toxin‐mediated liver fibrosis in vitro. Finally, they were cultured in a DLM‐containing medium to observe the viability and functions of the damaged hepatocytes, and the hypothesis of this research was proved, meaning that Glt‐HPA‐DLM acting on damaged hepatocytes may repair them. Results have shown that Glt‐HPA‐DLM was effective for hepatocytes culture and repaired injured hepatocytes from GaIN, CHCl3, and CCl4 (albumin synthesis was increased by 219, 108, and 12%, respectively, whereas relative lactate dehydrogenase activity was reduced by 38, 68, and 67%, after 5 days of culture, separately). This research shows promising effects against hepatic fibrosis and may have potential for liver cirrhosis in vivo. [ABSTRACT FROM AUTHOR]

Treatment with cross‐linking agents for stabilizing biomolecules is an integral step during the preparation of many extracellular matrix‐based tissue engineering scaffolds from mammalian organs. However, excess cross‐linking may cause nonavailability of biomolecules and consequent deterioration of bioinductive properties of the scaffold. The present study considered controlling the extent of cross‐linking in a porcine cholecyst extracellular matrix scaffold prepared by a nonenzymatic and nondetergent method, by ex situ incubation of the source organ in varying concentrations of neutral buffered formaldehyde (10, 4, 1 or 0%; v/v) for in situ cross‐linking of biomolecules. Reduction of the formaldehyde concentration resulted in an increase in the extent of biodegradation and a decrease in the compactness of the mesh‐like surface microarchitecture of the scaffold. Retention of collagen was maximum when treated with 10% neutral buffered formaldehyde without any variation in the content of elastin and sulphated glycosaminoglycans. Although there was a reduction in the quantity of growth factors following the cross‐linking, fibroblasts remained viable on the scaffolds. The retention of major biomolecule was maximum and autodigestion was minimum in the scaffold prepared by the ex situ treatment of cholecyst in 10% neutral buffered formalin and found suitable for preparing the tissue engineering scaffold. [ABSTRACT FROM AUTHOR]

Pulmonary disease is a worldwide public health problem that reduces the life quality and increases the need for hospital admissions as well as the risk of premature death. A common problem is the significant shortage of lungs for transplantation as well as patients must also take immunosuppressive drugs for the rest of their lives to keep the immune system from attacking transplanted organs. Recently, a new strategy has been proposed in the cellular engineering of lung tissue as decellularization approaches. The main components for the lung tissue engineering are: (1) A suitable biological or synthetic three‐dimensional (3D) scaffold, (2) source of stem cells or cells, (3) growth factors required to drive cell differentiation and proliferation, and (4) bioreactor, a system that supports a 3D composite biologically active. Although a number of synthetic as well biological 3D scaffold suggested for lung tissue engineering, the current favorite scaffold is decellularized extracellular matrix scaffold. There are a large number of commercial and academic made bioreactors, the favor has been, the one easy to sterilize, physiologically stimuli and support active cell growth as well as clinically translational. The challenges would be to develop a functional lung will depend on the endothelialized microvascular network and alveolar–capillary surface area to exchange gas. A critical review of the each components of lung tissue engineering is presented, following an appraisal of the literature in the last 5 years. This is a multibillion dollar industry and consider unmet clinical need. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) study is hampered by lacking of idea cell model which support effective HBV infection and meanwhile recapitulate hepatocyte biology function in vivo. In this study, we developed decellularized human liver scaffolds for cell culture and further applied for HBV infection. As a result, primary human hepatocytes (PHHs) engrafted into liver scaffolds and maintained differentiation with stable albumin secretion and liver‐specific gene expression. Comparing to mono‐layer cell culture, scaffold‐based three‐dimensional (3D) culture system significantly augment HBV DNA (including cccDNA), RNA level as well as HBsAg secretion. Moreover, HepG2‐NTCP cells cultured on 3D system exhibited higher infection efficiency and longer infection period in vitro. In addition, HBV DNA level was suppressed when anti‐HBV medicine Entecavir (ETV) introduced into HepG2‐NTCP 3D system. Herein, we evaluated the potential of decellularized human liver scaffold‐based in 3D cell culture and disclosed that scaffold‐based 3D culture system can facilitate HBV infection in vitro. This 3D culture system could be further applied in HBV‐related study. [ABSTRACT FROM AUTHOR]

Diseases that jeopardize the musculoskeletal system and cause chronic impairment are prevalent throughout the Western world. In Germany alone, ~1.8 million patients suffer from these diseases annually, and medical expenses have been reported to reach 34.2bn Euros. Although musculoskeletal disorders are seldom fatal, they compromise quality of life and diminish functional capacity. For example, musculoskeletal disorders incur an annual loss of over 0.8 million workforce years to the German economy. Among these diseases, traumatic skeletal muscle injuries are especially problematic because they can occur owing to a variety of causes and are very challenging to treat. In contrast to chronic muscle diseases such as dystrophy, sarcopenia, or cachexia, traumatic muscle injuries inflict damage to localized muscle groups. Although minor muscle trauma heals without severe consequences, no reliable clinical strategy exists to prevent excessive fibrosis or fatty degeneration, both of which occur after severe traumatic injury and contribute to muscle degeneration and dysfunction. Of the many proposed strategies, cell‐based approaches have shown the most promising results in numerous pre‐clinical studies and have demonstrated success in the handful of clinical trials performed so far. A number of myogenic and non‐myogenic cell types benefit muscle healing, either by directly participating in new tissue formation or by stimulating the endogenous processes of muscle repair. These cell types operate via distinct modes of action, and they demonstrate varying levels of feasibility for muscle regeneration depending, to an extent, on the muscle injury model used. While in some models the injury naturally resolves over time, other models have been developed to recapitulate the peculiarities of real‐life injuries and therefore mimic the structural and functional impairment observed in humans. Existing limitations of cell therapy approaches include issues related to autologous harvesting, expansion and sorting protocols, optimal dosage, and viability after transplantation. Several clinical trials have been performed to treat skeletal muscle injuries using myogenic progenitor cells or multipotent stromal cells, with promising outcomes. Recent improvements in our understanding of cell behaviour and the mechanistic basis for their modes of action have led to a new paradigm in cell therapies where physical, chemical, and signalling cues presented through biomaterials can instruct cells and enhance their regenerative capacity. Altogether, these studies and experiences provide a positive outlook on future opportunities towards innovative cell‐based solutions for treating traumatic muscle injuries—a so far unmet clinical need. [ABSTRACT FROM AUTHOR]

Adult skeletal muscle can regenerate effectively after mild physical or chemical insult. Muscle trauma or disease can overwhelm this innate capacity for regeneration and result in heightened inflammation and fibrotic tissue deposition resulting in loss of structure and function. Recent studies have focused on biomaterial and stem cell‐based therapies to promote skeletal muscle regeneration following injury and disease. Many stem cell populations besides satellite cells are implicated in muscle regeneration. These stem cells include but are not limited to mesenchymal stem cells, adipose‐derived stem cells, hematopoietic stem cells, pericytes, fibroadipogenic progenitors, side population cells, and CD133+ stem cells. However, several challenges associated with their isolation, availability, delivery, survival, engraftment, and differentiation have been reported in recent studies. While acellular scaffolds offer a relatively safe and potentially off‐the‐shelf solution to cell‐based therapies, they are often unable to stimulate host cell migration and activity to a level that would result in clinically meaningful regeneration of traumatized muscle. Combining stem cells and biomaterials may offer a viable therapeutic strategy that may overcome the limitations associated with these therapies when they are used in isolation. In this article, we review the stem cell populations that can stimulate muscle regeneration in vitro and in vivo. We also discuss the regenerative potential of combination therapies that utilize both stem cell and biomaterials for the treatment of skeletal muscle injury and disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1246–1262, 2019. [ABSTRACT FROM AUTHOR]

Both volumetric muscle loss (VML) and muscle degenerative diseases lead to an important decrease in skeletal muscle mass, condition that nowadays lacks an optimal treatment. This issue has driven towards an increasing interest in new strategies in tissue engineering, an emerging field that can offer very promising approaches. In addition, the discovery of induced pluripotent stem cells (iPSCs) has completely revolutionized the actual view of personalized medicine, and their utilization in skeletal muscle tissue engineering could, undoubtedly, add myriad benefits. In this review, we want to provide a general vision of the basic aspects to consider when engineering skeletal muscle tissue using iPSCs. Specifically, we will focus on the three main pillars of tissue engineering: the scaffold designing, the selection of the ideal cell source and the addition of factors that can enhance the resemblance with the native tissue. [ABSTRACT FROM AUTHOR]

Purpose: Advances in additive manufacturing processes are enabling the fabrication of surrogate bone structures for applications including use in high‐resolution anthropomorphic phantoms. In this research, a simple numerical model is proposed that enables the generation of microarchitecture with similar statistical distribution to trabecular bone. Methods: A human humerus, radius, ulna, and several vertebrae were scanned on the Imaging and Medical beamline at the Australian Synchrotron and the proposed numerical model was developed through the definition of two complex functions that encode the trabecular thickness and position‐dependant spacing to generate volumetric surrogate trabecular structures. The structures reproduced those observed at 19 separate axial locations through the experimental bone volumes. The applicability of the model when incorporating a two‐material approximation to absorption‐ and phase‐contrast CT was also investigated through simulation. Results: The synthetic structures, when compared with the real trabecular microarchitecture, yielded an average mean thickness error of 2 μm, and a mean difference in standard deviation of 33 μm for the humerus, 24 μm for the ulna and radius, and 15 μm for the vertebrae. Simulated absorption‐ and propagation‐based phase contrast CT projection data were generated and reconstructed using the derived mathematical simplifications from the two‐material approximation, and the phase‐contrast effects were successfully demonstrated. Conclusions: The presented model reproduced trabecular distributions that could be used to generate phantoms for quality assurance and validation processes. The implication of utilizing a two‐material approximation results in simplification of the additive manufacturing process and the generation of synthetic data that could be used for training of machine learning applications. [ABSTRACT FROM AUTHOR]

Even the efficacy of substrate and mechanical stimuli in addition to biochemical cues have been recognized in many studies of stem cell differentiation, few studies have been reported on the differentiation into esophageal epithelial cells. Therefore, the aim of this study was set to propose a method of differentiating stem cells into esophageal epithelial cells according to biochemical reagent concentration, substrate properties, and mechanical forces. After the concentration of all‐trans retinoic acid was determined as 5 μM by a baseline experiment, the degree of differentiation was compared in three different kinds of substrates: cover glass, polyurethane (PU) membrane, and electrospun PU sheet (ePU). Then, on the substrate showing the more positive results, that is, ePU, two types of mechanical forces, intermittent hydrostatic pressure (IHP), and shear stress (SS), were applied individually at different magnitudes for the latter 7 days of an overall incubation period of 14 days. Following various biological assays, the lower IHP (50 mmHg) resulted in greater positive effects than the others. Even with cessation of the mechanical force, the relevant markers were remarkably increased. Although the range of factors regulating differentiation was limited, this study nonetheless demonstrated the combinational effects of mechanical force along with substrate type for the first time in related studies. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 552–560, 2019. [ABSTRACT FROM AUTHOR]

Decellularized liver scaffolds based liver engineering is a promising approach toward developing functional liver surrogates. However, a major obstacle to long‐term transplantation is the hemocompatibility of the bioengineered liver surrogates. One approach to improve the hemocompatibility of engineered liver surrogates is re‐endothelialization. In the current study, immortalized endothelial cells were perfused for re‐endothelialization of decellularized rat liver scaffolds. When compared to the media‐based perfusion approach, gelatin hydrogels‐based perfusion significantly increased the number of cells that were retained in the decellularized liver scaffolds and the vascular lumen coverage ratio. Endothelial cells were lining along the vasculatures of the decellularized liver scaffolds and actively proliferating. Re‐endothelialization improved the blood retention ability of the liver scaffold vasculatures. Doppler ultrasound detected active blood flows within the re‐endothelialized liver scaffold transplants 8 days post‐transplantation. Our results strengthened the feasibility of developing bioengineered liver surrogates utilizing decellularized liver scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 392–402, 2019. [ABSTRACT FROM AUTHOR]

Artificial tissue‐engineered grafts offer a potential alternative to autologous tissue grafts for patients, which can be traumatic. After decellularizing Papio hamadryas esophagus and studying the morphology and physical properties of the extracellular matrix (ECM), we generated electrospun polyamide‐6 based scaffolds to mimic it. The scaffolds supported a greater mechanical load than the native ECM and demonstrated similar 3D microstructure, with randomly aligned fibers, 90% porosity, 29 μm maximal pore size, and average fiber diameter of 2.87 ± 0.95 µm. Biocompatibility studies showed that human adipose‐ and bone marrow‐derived mesenchymal stromal cells (AD‐MSC and BMD‐MSC) adhered to the scaffold surface and showed some proliferation: scaffold cell coverage was 25% after 72 h of incubation when seeded with 1000 cells/mm2; cells elongated processes along the polyamide‐6, although they flattened 1.67–4 times less than on cell culture plastic. Human umbilical vein endothelial cells, however, showed poor adherence and proliferation. We thus provide in vitro evidence that polyamide‐6 scaffolds approximating the esophageal biomechanics and 3D topography of nonhuman primates may provide a biocompatible substrate for both AD‐MSC and BMD‐MSCs, supporting their adhesion and survival to some degree. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 253–268, 2019. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) cancer models are overlooking the scientific landscape with the primary goal of bridging the gaps between two‐dimensional (2D) cell lines, animal models and clinical research. Here, we describe an innovative tissue engineering approach applied to colorectal cancer (CRC) starting from decellularized human biopsies in order to generate an organotypic 3D‐bioactive model. This in vitro 3D system recapitulates the ultrastructural environment of native tissue as demonstrated by histology, immunohistochemistry, immunofluorescence and scanning electron microscopy analyses. Mass spectrometry of proteome and secretome confirmed a different stromal composition between decellularized healthy mucosa and CRC in terms of structural and secreted proteins. Importantly, we proved that our 3D acellular matrices retained their biological properties: using CAM assay, we observed a decreased angiogenic potential in decellularized CRC compared with healthy tissue, caused by direct effect of DEFA3. We demonstrated that following a 5 days of recellularization with HT‐29 cell line, the 3D tumor matrices induced an over‐expression of IL‐8, a DEFA3‐mediated pathway and a mandatory chemokine in cancer growth and proliferation. Given the biological activity maintained by the scaffolds after decellularization, we believe this approach is a powerful tool for future pre‐clinical research and screenings. [ABSTRACT FROM AUTHOR]

Abstract: Whole kidney decellularization is a promising approach in regenerative medicine for engineering a functional organ. The reaction of the potential host depends on the biocompatibility of these decellularized constructs. Despite the proven ability of decellularized kidney scaffolds to guide cell attachment and growth, little is known about biocompatibility and hemocompatibility of these scaffolds. Our aim is to prepare decellularized kidneys of a clinically relevant size and evaluate its biocompatibility and hemocompatibility. Porcine kidneys were cannulated via the renal artery, and then perfused with 0.1% sodium dodecyl sulfate solution. Hematoxylin and eosin as well as DAPI staining confirmed cellular clearance from native kidneys in addition to preservation of the microstructure. SEM confirmed the absence of any cellular content within the scaffold, which is maintained in a well‐organized 3D architecture. Decellularized kidneys retained the intact renal vasculature upon examination with contrast radiography. The essential structural extracellular matrix molecules were well‐preserved. Scaffolds were susceptible to enzymatic degradation upon collagenase treatment. Scaffolds showed a good hemocompatibility when exposed to porcine blood. Decellularization was efficient to remove 97.7% of DNA from native kidneys in addition to the immunogenic and pathogenic antigens. Scaffolds did not induce the human immune response in vitro. Decellularized kidneys were non‐cytotoxic to pig kidney cells (PKs). PKs were able to grow and proliferate within the decellularized renal scaffolds with maintaining a higher function than cells grown as monolayers. Thus, we have developed a rapid decellularization technique for generating biocompatible kidney scaffolds that represents a step toward development of a transplantable organ. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2034–2047, 2018. [ABSTRACT FROM AUTHOR]

This study investigates the extent of cell seeding as well as lumen patency in acellular Internal mammary artery (IMA) scaffolds that have been re-cellularized by omentum as a natural bioreactor. Sixteen Virgin female Wistar rats were selected for implantation of acellular scaffold in omentum. Following laparotomy omentum was retracted to the outside of the abdomen and the more vascularized portion of it was selected for the experiment. The scaffold was wrapped by omentum and placed between two layers of rectus muscles that have been previously dissected. Samples were taken from scaffolds at 2 and 3 months for histopathological evaluation. All the grafts were explanted at 2 and 3 months and the lumens were completely patent compared to the native scaffold. The histology of implanted IMA after 2 and 3 months showed progressive recellularization especially by smooth muscle cells over the media layer. CD 34 staining was positive adjacent to the grafts which showed well angiogenesis. Trichrome and Movat's Pentachrome staining showed normal collagen formation in the inner media layer. Promising results obtained from the introduced protocol for in vivo recellularization, including patent lumen and proper cell seeding, encourages application of the mentioned technique for experimental vascular graft application. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2685-2693, 2017. [ABSTRACT FROM AUTHOR]

For many cellular therapies being evaluated in preclinical and clinical trials, the mechanisms behind their therapeutic effects appear to be the secretion of growth factors and cytokines, also known as paracrine activity. Often, delivered cells are transient, and half-lives of the growth factors that they secrete are short, limiting their long-term effectiveness. The goal of this study was to optimize a hydrogel system capable of in situ cell delivery that could sequester and release growth factors secreted from those cells after the cells were no longer present. Here, we demonstrate the use of a fast photocross-linkable heparin-conjugated hyaluronic acid (HA-HP) hydrogel as a cell delivery vehicle for sustained growth factor release, which extends paracrine activity. The hydrogel could be modulated through cross-linking geometries and heparinization to support sustained release proteins and heparin-binding growth factors. To test the hydrogel in vivo, we used it to deliver amniotic fluid-derived stem (AFS) cells, which are known to secrete cytokines and growth factors, in full thickness skin wounds in a nu/nu murine model. Despite transience of the AFS cells in vivo, the HA-HP hydrogel with AFS cells improved wound closure and reepithelialization and increased vascularization and production of extracellular matrix in vivo. These results suggest that HA-HP hydrogel has the potential to prolong the paracrine activity of cells, thereby increasing their therapeutic effectiveness in wound healing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1986-2000, 2017. [ABSTRACT FROM AUTHOR]

Renal transplantation is well established as the optimal form of renal replacement therapy but is restricted by the limited pool of organs available for transplantation. The whole organ decellularisation approach is leading the way for a regenerative medicine solution towards bioengineered organ replacements. However, systematic preoptimization of both decellularization and recellularization parameters is essential prior to any potential clinical application and should be the next stage in the evolution of whole organ decellularization as a potential strategy for bioengineered organ replacements. Here we have systematically assessed two fundamental parameters (concentration and duration of perfusion) with regards to the effects of differing exposure to the most commonly used single decellularizing agent (sodium dodecyl sulphate/SDS) in the perfusion decellularization process for whole rat kidney ECM bioscaffolds, with findings showing improved preservation of both structural and functional components of the whole kidney ECM bioscaffold. Whole kidney bioscaffolds based on our enhanced protocol were successfully recellularized with rat primary renal cells and mesenchymal stromal cells. These findings should be widely applicable to decellularized whole organ bioscaffolds and their optimization in the development of regenerated organ replacements for transplantation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1352-1360, 2017. [ABSTRACT FROM AUTHOR]

Abstracts of articles including "Antiphospholipid antibodies inhibit the TAM receptor pathway in human first trimester trophoblast cells," "Effect of HSV-2 infection on TAM receptors expression in first trimester trophoblast cells" and "Exomes mediate endotoxin tolerance in human placenta" are presented.

Decellularization processes may variably distort or degrade extracellular matrix (ECM) structure. In this study, two perfusion routes (PR) were tested on SD rat lung samples. One decellularization protocol, PR1, was perfused through the pulmonary artery. The other decellularization protocol, PR2, was perfused through the trachea. Both decellularization protocols were used by the same detergent-based (sodium dodecyl sulphate and Triton X-100) with different flow continuous perfusion. There was no visible difference in vessel architecture between PR1- and PR2-decellularized scaffold. However, the airway structure and alveoli architecture of pulmonary decellularized scaffolds generated through PR2 at a flow rate of 8 mL/min were destroyed partly when compared to that in native lung and PR1-decellularized scaffold. Ultramicroscopic assessment of scaffolds was similar in both protocols and showed filamentous ECM with preserved fiber disposition and structure. Histological analysis and immunostaining showed no detectable cells remaining in the pulmonary scaffolds compare with native lung. The DNA concentration was significantly reduced in the decellularized scaffolds compared to the native lungs. A549 cells reseeded onto decellularized pulmonary scaffolds were no significant difference between PR1 and PR2 in cell viability, p > 0.05. We conclude that under the same high flow velocity status, perfusion decellularization through the pulmonary artery may be an optimal pathway to obtain decellularized scaffolds for pulmonary regeneration. This article is protected by copyright. All rights reserved. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2567-2575, 2016. [ABSTRACT FROM AUTHOR]

The kidney is the most important organ for water homeostasis and waste excretion. It performs several important physiological functions for homeostasis: it filters the metabolic waste out of circulation, regulates body fluid balances, and acts as an immune regulator and modulator of cardiovascular physiology. The development of in vitro renal disease models with pluripotent stem cells (both human embryonic stem cells and induced pluripotent stem cells) and the generation of robust protocols for in vitro derivation of renal-specific-like cells from patient induced pluripotent stem cells have just emerged. Here we review major findings in the field of kidney regeneration with a major focus on the development of stepwise protocols for kidney cell production from human pluripotent stem cells and the latest advances in kidney bioengineering (i.e. decellularized kidney scaffolds and bioprinting). The possibility of generating renal-like three-dimensional structures to be recellularized with renal-derived induced pluripotent stem cells may offer new avenues to develop functional kidney grafts on-demand. [ABSTRACT FROM AUTHOR]

The immediate physical and chemical surroundings of cells provide important biochemical cues for their behavior. Designing and tailoring biomaterials for controlled cell signaling and extracellular matrix (ECM) can be difficult due to the complexity of the cell-surface relationship. To address this issue, our research has led to the development of a polydimethylsiloxane (PDMS) scaffold with defined microtopography and chemistry for surface driven ECM assembly. When human fibroblasts were cultured on this microtextured PDMS with 2-6 µm wide vertical features, significant changes in morphology, adhesion, actin cytoskeleton, and fibronectin generation were noted when compared with cells cultured on unmodified PDMS. Investigation of cellular response and behavior was performed with atomic force microscopy in conjunction with fluorescent labeling of focal adhesion cites and fibronectin in the ECM. Changes in the surface topography induced lower adhesion, an altered actin cytoskeleton, and compacted units of fibronectin similar to that observed in vivo. Overall, these findings provide critical information of cell-surface interactions with a microtextured, polymer substrate that can be used in the field of tissue engineering for controlling cellular ECM interactions. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 861-869, 2015. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a method to generate multi-organ acellular matrices. Using a foetal sheep model have developed a method of systemic pulsatile perfusion via the umbilical artery which allows for simultaneous multi-organ decellularization. Twenty sheep foetuses were systemically perfused with Triton X-100 and sodium dodecyl sulphate. Following completion of the whole-body decellularization, multiple biopsy samples were taken from different parts of 21 organs to ascertain complete cell component removal in the preserved extracellular matrices. Both the natural and decellularized organs were subjected to several examinations. The samples were obtained from the skin, eye, ear, nose, throat, cardiovascular, respiratory, gastrointestinal, urinary, musculoskeletal, central nervous and peripheral nervous systems. The histological results depicted well-preserved extracellular matrix ( ECM) integrity and intact vascular structures, without any evidence of residual cellular materials, in all decellularized bioscaffolds. Scanning electron microscope (SEM) and biochemical properties remained intact, similar to their age-matched native counterparts. Preservation of the collagen structure was evaluated by a hydroxyproline assay. Dense organs such as bone and muscle were also completely decellularized, with a preserved ECM structure. Thus, as shown in this study, several organs and different tissues were decellularized using a perfusion-based method, which has not been previously accomplished. Given the technical challenges that exist for the efficient generation of biological scaffolds, the current results may pave the way for obtaining a variety of decellularized scaffolds from a single donor. In this study, there have been unique responses to the single acellularization protocol in foetuses, which may reflect the homogeneity of tissues and organs in the developing foetal body. [ABSTRACT FROM AUTHOR]

Stem and progenitor cells play important roles in organogenesis during development and in tissue homeostasis and response to injury postnatally. As the regenerative capacity of many human tissues is limited, cell replacement therapies hold great promise for human disease management. Pluripotent stem cells such as embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are prime candidates for the derivation of unlimited quantities of clinically relevant cell types through development of directed differentiation protocols, that is, the recapitulation of developmental milestones in in vitro cell culture. Tissue-specific progenitors, including progenitors of endodermal origin, are important intermediates in such protocols since they give rise to all mature parenchymal cells. In this review, we focus on the in vivo biology of embryonic endodermal progenitors in terms of key transcription factors and signaling pathways. We critically review the emerging literature aiming to apply this basic knowledge to achieve the efficient and reproducible in vitro derivation of endodermal progenitors such as pancreas, liver and lung precursor cells. J. Cell. Physiol. 230: 246-258, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objectives: Properties of cell culture supports obtained from ultrathin multilayer films containing anionic natural polysaccharides (PSacs) and a synthetic polycation were studied. Materials and methods: Supports were prepared via a layer-by-layer (LbL) self-assembly deposition method. Polymers used were: heparin (Hep), chondroitin sulphate (CS), hyaluronic acid (HA), and ?-carrageenan (Car) as polyanions, and diazoresin (DR) as a polycation. PSac layers were crosslinked with DR layers by irradiation with UV light absorbed by DR resin. Results: DR/PSac films are very efficient cell culture growth supports as found from experiments with human mesenchymal stem cells (hMSCs). Irradiation of the films resulted in changing zeta potential of outermost layers of both DR and PSac to more negative values, and in increased film hydrophobicity, as found from the contact angle measurements. Photocrosslinking of the supports led to their increased stability. Conclusions: The supports allow for obtaining intact cell monolayers faster than when typical polystyrene tissue culture plates are used. Moreover, these monolayers spontaneously detach permitting formation of new cell layers on these surfaces relatively early during culture, compared to cells cultured on commonly used tissue culture plastic. [ABSTRACT FROM AUTHOR]

An author index for the 76th volume of the "American Journal of Reproductive Immunology" is presented.

The creation of engineered intestinal tissue has recently stimulated new endeavors with the ultimate goal of intestinal replacement for massive resections of bowel. In this context, we investigated the effect of hyaluronic acid (HA) on the physicochemical characteristics of gelatin-collagen scaffolds and its cytocompatibilty to the human intestinal epithelial Caco-2 cell line in vitro. Gelatin/collagen hybrid scaffolds with different concentrations of HA were prepared by solvent casting and freeze-drying techniques and subsequent chemical crosslinking by genipin. The morphologies of the scaffolds were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. In vitro tests were carried out in phosphate-buffered saline (PBS) solution to study the swelling ratio and the biostability of the scaffolds. It was found that the porous structure of the scaffolds could be tailored by further addition of HA. Moreover, both the swelling ratio and the degradation rate of the scaffold increased by addition of HA. A resazurin-based cell viability assay was employed to determine the viability and estimate the number of scaffold-adherent Caco-2 cells. The assay indicated that the scaffolds were all cytocompatible. We concluded that addition of less than 15% HA to scaffolds with a composition of 9:1 gelatin:collagen results only in incremental improvement in the structural characteristics and cytocompatibility of the gelatin-collagen scaffolds. However, the scaffolds with 25% HA exhibited remarkable enhancement in physicochemical characteristics of the scaffolds including cell viability, growth, and attachment as well as their physical structure. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3130-3139, 2014. [ABSTRACT FROM AUTHOR]

The achievement of novel findings in stem cell research were the subject of the meeting organized by Stem Cell Research Italy (SCR Italy) and by the International Society for Cellular Therapy-Europe (ISCT). Stem cell therapy represents great promise for the future of molecular and regenerative medicine. The use of several types of stem cells is a real opportunity to provide a valid approach to curing several untreatable human diseases. Before it is suitable for clinical applications, stem cell biology needs to be investigated further and in greater detail. Basic stem cell research could provide exact knowledge regarding stem cell action mechanisms, and pre-clinical research on stem cells on an in vivo model of disease provides scientific evidence for future human applications. Applied stem cell research is a promising new approach to handling several diseases. Along with tissue engineering, it offers a new and promising discipline that can help to manage human pathologies through stem cell therapy. All of these themes were discussed in this meeting, covering stem cell subtypes with their newest basic and applied research. J. Cell. Physiol. 227: 2283-2286, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]