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Bullous pemphigoid (BP) is an autoimmune blistering disease that targets the haemidesmosomal proteins, mainly BP180. Extracellular vesicles (EVs) have been demonstrated to carry tissue-specific autoantigens in the setting of autoimmune diseases and transplant organ rejection; this phenomenon was demonstrated to have pathogenic implications in autoimmune diseases and to correlate with transplant rejection severity. The purpose of this study was to identify the presence of BP targeted autoantigens in blister fluid derived EVs. We isolated, by size exclusion chromatography, EVs derived from blisters of BP-patients and from suction blisters of healthy donors. EV characterization was performed by flow cytometry and nanoparticle tracking analysis. Western blot analysis was used to investigate the presence of autoantigens. A suspension enriched in EVs was efficiently obtained from blister fluid from patients and healthy donors. EV-enriched fractions were enriched in particles with a size distribution characterizing small-EVs (main peak was present at 94.5 nm). BP180 was found, by western blot analysis, in EVs derived from blister fluid of 3 out 6 BP patients and in none of EVs isolated from suction blister fluid of healthy donors. BP230 and Dsg1 were not detectable in EVs of any of the samples. No specific clinical characteristics seemed to correlate to the presence of BP180 in EVs. The discovery of BP180 in EVs derived from blister fluid might help understanding BP pathogenesis.

Bullous pemphigoid (BP) is an autoimmune blistering disease that targets the haemidesmosomal proteins, mainly BP180. Extracellular vesicles (EVs) have been demonstrated to carry tissue-specific autoantigens in the setting of autoimmune diseases and transplant organ rejection; this phenomenon was demonstrated to have pathogenic implications in autoimmune diseases and to correlate with transplant rejection severity. The purpose of this study was to identify the presence of BP targeted autoantigens in blister fluid derived EVs. We isolated, by size exclusion chromatography, EVs derived from blisters of BP-patients and from suction blisters of healthy donors. EV characterization was performed by flow cytometry and nanoparticle tracking analysis. Western blot analysis was used to investigate the presence of autoantigens. A suspension enriched in EVs was efficiently obtained from blister fluid from patients and healthy donors. EV-enriched fractions were enriched in particles with a size distribution characterizing small-EVs (main peak was present at 94.5nm). BP180 was found, by western blot analysis, in EVs derived from blister fluid of 3 out 6 BP patients and in none of EVs isolated from suction blister fluid of healthy donors. BP230 and Dsg1 were not detectable in EVs of any of the samples. No specific clinical characteristics seemed to correlate to the presence of BP180 in EVs. The discovery of BP180, the most important autoantigen targeted in BP, in EVs derived from blister fluid represent a milestone in the understanding of BP pathogenesis.

Regenerative strategies for human articular cartilage are still challenging despite the presence of resident progenitor cell population. Today, many efforts in the field of regenerative medicine focus on the use of platelet derivatives due to their ability to reactivate endogenous mechanisms supporting tissue repair. While their use in orthopedics continues, mechanisms of action and efficacy need further characterization. We describe that the platelet lysate (PL) is able to activate chondro-progenitor cells in a terminally differentiated cartilage tissue. Primary cultures of human articular chondrocytes (ACs) and cartilage explants were set up from donor hip joint biopsies and were treated in vitro with PL. PL recruited a chondro-progenitors (CPCs)-enriched population from ex vivo cartilage culture, that showed high proliferation rate, clonogenicity and nestin expression. CPCs were positive for in vitro tri-lineage differentiation and formed hyaline cartilage-like tissue in vivo without hypertrophic fate. Moreover, the secretory profile of CPCs was analyzed, together with their migratory capabilities. Some CPC-features were also induced in PL-treated ACs compared to fetal bovine serum (FBS)-control ACs. PL treatment of human articular cartilage activates a stem cell niche responsive to injury. These facts can improve the PL therapeutic efficacy in cartilage applications.

Standard treatments of chronic skin ulcers based on the direct application of dressings still present several limits with regard to a complete tissue regeneration. Innovative strategies in tissue engineering offer materials that can tune cell behavior and promote growth tissue favoring cell recruitment in the early stages of wound healing. A combination of Alginate (Alg), Sericin (SS) with Platelet Lysate (PL), as a freeze-dried sponge, is proposed to generate a bioactive wound dressing to care skin lesions. Biomembranes at different composition were tested for the release of platelet growth factors, cytotoxicity, protective effects against oxidative stress and cell proliferation induction. The highest level of the growth factors release occurred within 48 h, an optimized time to burst a healing process in vivo, the presence of SS differently modulated the release of the factors by interaction with the proteins composing the biomembranes. Any cytotoxicity was registered, whereas a capability to protect cells against oxidative stress and induce proliferation was observed when PL was included in the biomembrane. In a mouse skin lesion model, the biomembranes with PL promoted the healing process, inducing an accelerated and more pronounced burst of inflammation, formation of granulation tissue and new collagen deposition, leading to a more rapid skin regeneration.

Due to their osteoconductive and inductive properties, a variety of calcium phosphate (CaP) scaffolds are commonly used in orthopaedics as graft material to heal bone defects. In this study, we have used two CaP scaffolds with different hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ratios (MBCP®; 60/40 and MBCP+ ®; 20/80) to investigate their intrinsic capacity to favour human bone marrow stem cells (hBMSCs) osteogenic differentiation capacity. We report that MBCP+ ® showed in in vitro culture model a higher rate of calcium ion release in comparison with MBCP®. In two defined coculture systems, the hBMSC seeded onto MBCP+ ® presented an increased amount of VEGF secretion, resulting in an enhanced endothelial cell proliferation and capillary formation compared with hBMSC seeded onto MBCP®. When both ceramics combined with hBMSC were implanted in a nude mouse model, we observed a faster osteogenic differentiation and enhancement mature bone deposition sustained by the presence of a vast host vasculature within the MBCP+ ® ceramics. Bone formation was observed in samples highly positive to the activation of calcium sensing receptor protein (CaSr) on the surface of seeded hBMSC that also shown higher BMP-2 protein expression. With these data we provide valuable insights in the possible mechanisms of ossification and angiogenesis by hBMSC that we believe to be primed by calcium ions released from CaP scaffolds. Evidences could lead to an optimization of ceramic scaffolds to prime bone repair.

Advanced therapeutics, specifically cell and gene therapies, provide an opportunity to target previously unmet clinical conditions and offer a potential solution to the social and economic burden associated with an aging population [1,2]. Human mesenchymal stem/stromal cells (hMSCs) are a promising cell therapy candidate for the treatment of numerous clinical indications [3]; however, a transformation is required in the way we isolate, manufacture, characterize and deliver these therapies to ensure they are both efficacious and affordable [2,4]. Manufacture of hMSCs requires in vitro expansion to increase the available number of cells to meet clinical demand; however, progress is impeded by the lack of advanced methods for the isolation and expansion of cells that are scalable, amenable for automation and closed. Many allogeneic processes still require manual intervention which has significant quality and cost implications [5], and developing reproducible, consistent bioprocesses is still a major challenge. Even when a scale-out approach is to be employed (e.g., for autologous therapies), there is a significant practical challenge of manipulating, processing and segregating multiple production batches in an aseptic, closed manner. Such processes demand small units for manufacture in which line segregation is a priority in order to avoid product–patient mismatch and disease transmission. As such, there is an industrial trend toward automated systems as it is increasingly recognized that such systems facilitate consistent manufacture and will play a pivotal role in the translation of cell therapies by improving quality control, process economics, scalability, process capability and provide a platform for understanding process variation and optimization [6]. Through AUTOSTEM (European Commission Horizon 2020 funded research and innovation actions), academic and industrial groups from across the EU are working in collaboration to take a holistic approach to enable large-scale hMSC production, at clinical-grade quality, by implementing a robotic automated pipeline for cell isolation and culture [7]. AUTOSTEM builds on the ground-breaking work of the StemCellFactory project [8] which built and demonstrated an automated robotic pipeline for the production of human induced pluripotent cell lines (Figure 1). AUTOSTEM develops this technology further to enable automated, closed and good manufacturing practice (GMP)ready hMSCs (a ‘StromalCellFactory’) and will focus on the development of

Recent increasing evidence supports a role for neuronal type signaling in bone. Specifically glutamate receptors have been found in cells responsible for bone remodeling, namely the osteoblasts and the osteoclasts. While most studies have focused on ionotropic glutamate receptors, the relevance of the metabotropic glutamate signaling in bone is poorly understood. Specifically type 1 metabotropic glutamate (mGlu1) receptors are expressed in bone, but the effect of its ablation on skeletal development has never been investigated. Here we report that Grm1crv4/crv4 mice, homozygous for an inactivating mutation of the mGlu1 receptor, and mainly characterized by ataxia and renal dysfunction, exhibit decreased body weight, bone length and bone mineral density compared to wild type (WT) animals. Blood analyses of the affected mice demonstrate the absence of changes in circulating factors, such as vitamin D and PTH, suggesting renal damage is not the main culprit of the skeletal phenotype. Cultures of osteoblasts lacking functional mGlu1 receptors exhibit less homogeneous collagen deposition than WT cells, and present increased expression of osteocalcin, a marker of osteoblast maturation. These data suggest that the skeletal damage is directly linked to the absence of the receptor, which in turn leads to osteoblasts dysfunction and earlier maturation. Accordingly, skeletal histomorphology suggests that Grm1crv4/crv4 mice exhibit enhanced bone maturation, resulting in premature fusion of the growth plate and shortened long bones, and further slowdown of bone apposition rate compared to the WT animals. In summary, this work reveals novel functions of mGlu1 receptors in the bone and indicates that in osteoblasts mGlu1 receptors are necessary for production of normal bone matrix, longitudinal bone growth, and normal skeletal development.

Platelet-rich plasma (PRP), a cocktail of platelet growth factors and bioactive proteins, has been proposed as a therapeutic agent to restore damaged articular cartilage. We report the biological effect of the platelet lysate (PL), a PRP derivative, on primary human articular chondrocytes cultured under both physiological and inflammatory conditions. When added to the culture medium, PL induced a strong mitogenic response in the chondrocytes. The in vitro expanded cell population maintained a chondrogenic redifferentiation potential as revealed by micromass culture in vitro and ectopic cartilage formation in vivo. Further, in chondrocytes cultured in the presence of the proinflammatory cytokine interleukin-1a (IL-1a), the PL induced a drastic enhancement of the synthesis of the cytokines IL-6 and IL-8 and of neutrophil-gelatinase associated lipocalin, a lipocalin expressed during chondrocyte differentiation and inflammation. These events were mediated by the p38 MAP kinase and NF-kB pathways. We observed that inflammatory stimuli activated phospo-MAP kinase-activated protein kinase 2, a direct target of p38. The proinflammatory effect of the PL was a transient phenomenon; after an initial upregulation, we observed significant reduction of the NF-kB activity together with the repression of the inflammatory enzyme cyclooxygenase-2. Moreover, the medium of chondrocytes cultured in the simultaneous presence of PL and IL-1a, showed a significant enhancement of the chemoattractant activity versus untreated chondrocytes. Our findings support the concept that the platelet products have a direct beneficial effect on articular chondrocytes and could drive in sequence a transient activation and the resolution of the inflammatory process, thus providing a rational for their use as therapeutic agents in cartilage inflammation and damage., The work was supported by institutional funds from the University of Genova and by European Union Projects (Angioscaff and GAMBA) and by a grant from Compagnia di San Paolo, Torino. The authors would like to thank Dr. Fiorella Descalzi and Dr. Maddalena Mastrogiacomo of our institute for helpful discussions and suggestions, Dr. Michele Grandizio for providing the biological samples, and the medical staff of the Recco Hospital (Recco, Genova, Italy) for their collaboration and support.

The aim of our study was to analyse the clinical and histological outcome after the treatment of focal cartilage defects in non-degenerative and degenerative knees with bone marrow stimulation and subsequent covering with a cell-free resorbable polyglycolic acid–hyaluronan (PGA-HA) implant immersed with autologous platelet-rich plasma (PRP). Fifty-two patients (mean age 44 years) with focal chondral defects in radiologically confirmed non-degenerative or degenerative knees were subjected to subchondral drilling arthroscopically. Subsequently, defects were covered with the PGA-HA implant immersed with autologous PRP. At 2-year follow-up, the patients’ situation was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and compared to the pre-operative situation and 3–12-month follow-up. Biopsies (n = 4) were harvested at 18–24 months after implantation and were analysed by histology and collagen type II immune staining. At 1- and 2-year follow-up, the KOOS showed clinically meaningful and significant (p

The GAMBA Consortium is developing a novel gene-activated matrix platform for bone and cartilage repair with a focus on osteoarthritis-related tissue damage. The scientific and technological objectives of this project are complemented with an innovative program of public outreach, actively linking patients and society to the evolvement of this project. The GAMBA platform will implement a concept of spatiotemporal control of regenerative bioactivity on command and demand. A gene activated matrix is a biomaterial with embedded gene vectors that will genetically modify cells embedded in or colonising the matrix. The platform comprises modules that self-adapt to the biological environment and that can be independently addressed with endogenous biological and exogenous physical or pharmacological stimuli, resulting in a temporally and spatially coordinated growth factor gene expression pattern. This reproduces, within the matrix, key elements of natural tissue formation. The modules are a biomimetic hyaluronan gel, a ceramic matrix, growth factor-encoding gene vector nanoparticles, magnetic nanoparticles and mesenchymal stem cells. Anatomical adaptivity is achieved with engineered thermal properties of the polymer matrix, which embeds other modules, selected according to functional requirements. Mechanical support is provided by Micro Macroporous Biphasic Calcium Phosphate (MBCP ™ ), a resorbable material approved for clinical use. Spatiotemporal control of bioactivity and responsiveness to physiological conditions is represented, firstly, in the spatial distribution and release profiles of gene vectors within the composite matrix and, secondly, by letting local and external biological or physical stimuli activate the promoters driving the expression of vector-encoded growth factor transgenes. This concept is implemented by a multidisciplinary team from leading European institutions. Here, we report on the concepts, objectives and some preliminary results of the GAMBA project which is funded in 7th Framework Programme of the European Union THEME [NMP-2009-2.3-1], Biomimetic gels and polymers for tissue repair.

Recent increasing evidence supports a role for neuronal type signaling in bone. Specifically glutamate receptors have been found in cells responsible for bone remodeling, namely the osteoblasts and the osteoclasts. While most studies have focused on ionotropic glutamate receptors, the relevance of the metabotropic glutamate signaling in bone is poorly understood. Specifically type 1 metabotropic glutamate (mGlu1) receptors are expressed in bone, but the effect of its ablation on skeletal development has never been investigated. Here we report that Grm1

The amniotic fluid is a new source of multipotent stem cells with a therapeutic potential for human diseases. Cultured at low cell density, human amniotic fluid stem cells (hAFSCs) were still able to generate colony-forming unit-fibroblast (CFU-F) after 60 doublings, thus confirming their staminal nature. Moreover, after extensive in vitro cell expansion hAFSCs maintained a stable karyotype. The expression of genes, such as SSEA-4, SOX2 and OCT3/4 was confirmed at early and later culture stage. Also, hAFSCs showed bright expression of mesenchymal lineage markers and immunoregulatory properties. hAFSCs, seeded onto hydroxyapatite scaffolds and subcutaneously implanted in nude mice, played a pivotal role in mounting a response resulting in the recruitment of host's progenitor cells forming tissues of mesodermal origin such as fat, muscle, fibrous tissue and immature bone. Implanted hAFSCs migrated from the scaffold to the skin overlying implant site but not to other organs. Given their in vivo: (i) recruitment of host progenitor cells, (ii) homing towards injured sites and (iii) multipotentiality in tissue repair, hAFSCs are a very appealing reserve of stem cells potentially useful for clinical application in regenerative medicine.

The extracellular matrix (ECM) is a complex of self assembled macromolecules. It is composed predominantly of collagens, non-collagenous glycoproteins, hyaluronan and proteoglycans. ECM is not only a scaffold for the cells; it serves also as a reservoir for growth factors and cytokines and modulates the cell activation status and turnover. ECM should be considered a dynamic network of molecules secreted by cells that in turn regulate cell behavior by modulating their proliferation and differentiation. The ECM provides structural strength to tissues, maintaining a complex architecture around the cells and the shape of organs. Various cell types secrete different matrix molecules and the nature and the amount of these molecules change during developmental age. Cartilage ECM is composed mainly of two components defining its mechano-physical properties: the collagenous network, responsible for the tensile strength of the cartilage matrix, and the proteoglycans (mainly aggrecan), responsible for the osmotic swelling and the elastic properties of the cartilage tissue. The conversion of cartilage into bone requires several processes that directly involve the different ECM components. Homeostasis of cartilage and bone is maintained by complex mechanisms controlling turnover and remodeling of ECM. In bone, as well as in cartilage, the ECM resident cells produce local factors, inflammatory mediators, and matrix-degrading enzymes. Turnover and degradation of normal and pathological matrices are dependent on the responses of the local cell to auto and paracrine anabolic and catabolic pathway.

Objective To analyze the growth trend of small uterine fibroids during early pregnancy, evaluating the potential factors involved, with particular interest in hCG levels. Design Observational study. Setting Tertiary care university hospital. Patient(s) Women who had an ultrasound diagnosis of small myomas (diameter, ≥10 mm and ≤50 mm) from January 2007 to December 2013, and who subsequently became pregnant within 1 year. Intervention(s) None. Main Outcome Measure(s) Three additional ultrasound examinations were performed during early pregnancy (7–8, 10–13, and 20–22 complete gestational weeks, respectively) and the modifications in diameter and volume of each uterine fibroid were recorded. A serial evaluation of hCG serum levels from 5–12 weeks was performed. Result(s) From the 109 women who fulfilled the study inclusion/exclusion criteria, a significant increase emerged, both for volume and diameter of the detected fibroids. Specifically, a median growth rate (GR) of 122% was observed during the interval of the first to the second ultrasound, whereas a median GR of 108% was detected during the interval between the second and the third ultrasound, and a median GR of 25% between the third and the fourth ultrasound. A significant positive correlation between hCG levels and diameter ( R = 0.69) of myomas between 5 and 12 weeks emerged. Conclusion(s) A remarkable nonlinear growth of small fibroids during initial pregnancy was observed, with a faster rate in the first trimester and a slowdown by midpregnancy. Those changes seem to be related to the similar increase of hCG levels until 12 weeks.

Background aims The amniotic fluid is a new source of multipotent stem cells with therapeutic potential for human diseases. In agreement with the regulatory requirement to reduce and possibly to avoid animal-derived reagents in the culture of cells intended for cell therapy, bovine serum, the most common supplement in the culture medium, was replaced by human platelet-derived growth factors. Methods. We tested a new culture medium to expand monolayers of human amniotic fluid stem cells (hAFSC) for clinical use. The AFSC were isolated by c-Kit selection and expanded in media supplemented with either bovine serum or a human platelet lysate (Lyset). Results We compared proliferation kinetics, colony-forming unit percentage, multilineage differentiation, immunophenotypic characterization and inhibition of peripheral blood mononuclear cell proliferation of the two AFSC cell cultures and we found no significant differences. Moreover, the karyotype analysis of the cells expanded in the presence of the platelet lysate did not present cytogenetic abnormalities and in vitro and in vivo studies revealed no cell tumorigenicity. Conclusions Platelet derivatives represent a rich source of growth factors that can play a safety role in the homeostasis, proliferation and remodeling of tissue healing. We propose human platelet extracts as a preferential alternative to animal serum for the expansion of stem cells for clinical applications.

Objective Runx2 (also known as Cbfa1) is a transcription factor required for chondrocyte maturation and osteoblast differentiation. While there is information on the regulation of its expression during osteogenesis, much less is known about it during cartilage maturation. Here we asked whether Runx2 expression and function are affected by retinoic acid (RA) and parathyroid hormone-related peptide (PTHrP), which represent an important stimulator and inhibitor of chondrocyte maturation, respectively. Design We first cloned and characterized Runx2 expressed by chick chondrocytes (cRunx2). We then constructed expression vectors of cRunx2 and a dominant-negative form (DN-cRunx2) and determined their effects on chondrocyte maturation in culture before and during retinoid and PTHrP treatment. Results cRunx2 showed similar transactivation activity to that of its mammalian counterparts although it has a very short QA domain and lacks a small portion of the PST domain. cRunx2 over-expression stimulated chondrocyte maturation, as indicated by increases in alkaline phosphatase activity (APase), mineralization, and type X collagen and MMP-13 expression, and by maintenance of Indian hedgehog (Ihh) expression. RA treatment stimulated cRunx2 gene expression and boosted its pro-maturation effects. PTHrP treatment blocked Runx2 expression and its pro-maturation effects. Over-expression of DN-cRunx2 inhibited maturation and even prevented RA from exerting its pro-maturation role. Conclusions As previously indicated by mammalian studies, cRunx2 has chondrocyte pro-maturation activity. Its expression and roles are favorably modulated by retinoid signaling but are completely inhibited by PTHrP. A model integrating cRunx2 with PTHrP, Ihh and retinoid signaling and operating during skeletogenesis is proposed. Copyright 2003 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

Extracellular Fatty Acid Binding Protein (Ex-FABP) is a 21 kDa lipocalin, expressed during chicken embryo development in hypertrophic cartilage, in muscle fibres and in blood granulocyte. The protein selectively binds with high affinity fatty acids, preferably long chain unsaturated fatty acids in chondrocyte and myoblast cultures Ex-FABP expression is increased by inflammatory-agents and repressed by anti-inflammatory-agents. In adult cartilage, Ex-FABP is expressed only in pathological conditions such as in dyschondroplastic and osteoarthritic chicken cartilage. We propose that lipocalin Ex-FABP represents a stress protein physiologically expressed in tissues where active remodelling is taking place during development and also present in tissues characterized by a stress response due to pathological conditions.

To evaluate the risk of miscarriage in the subsequent pregnancy after a loop electrosurgical excision procedure (LEEP), also considering time elapsed from LEEP to pregnancy.Multicenter, retrospective cohort study.Tertiary care university hospitals.Women who had undergone LEEP from January 2000 to December 2011. Women with histologic assessment of low-grade cervical dysplasia, not requiring subsequent surgical treatment, constituted the control group.None.The first pregnancy after the procedure was evaluated, and only women with singleton spontaneous pregnancies were considered. Women with time intervals of12 months and women with intervals of ≥12 months or more from LEEP to pregnancy were then compared, to identify adjusted odds ratios for miscarriage.In women previously treated with LEEP, a total of 116 cases of miscarriage (18.1%) was reported. The mean time interval from LEEP to pregnancy for women with miscarriage compared with women without miscarriage was significantly shorter (25.1 ± 11.7 months vs. 30.1 ± 13.3 months). A higher rate of miscarriage in women with a LEEP-to-pregnancy interval of12 months compared with controls emerged (28.2% vs. 13.4%; adjusted odds ratio 2.60, 95% confidence interval 1.57-4.3). No significant difference in the rate of miscarriage in women with a LEEP-to-pregnancy interval of ≥12 months compared with controls emerged.Women with a time interval from LEEP to pregnancy of12 months are at increased risk for miscarriage.

The therapeutic use of stem cells is a very promising strategy in the area of regenerative medicine. The stem cell regenerative paradigm has been mostly based on the assumption that progenitor cells play a critical role in tissue repair by their plasticity and differentiation potential. However, recent works suggest that the mechanism underlying the benefits of stem cell transplantation might relate to a paracrine modulatory effect rather than the replacement of affected cells at the site of injury. Preclinical and clinical skeletal studies, conducted in animal and adult series, support the use of mesenchymal stem cells (MSCs) for bone healing in critical clinical situations. These results have led to an increasing number of papers reporting the use of MSCs in adult clinical trials, whereas only few papers reported the use of these cells in pediatric skeletal disorders, probably because of unknown long-term results and long-life consequences of cellular therapy. The exponential growth of knowledge in adult MSCs could be translated and applied to pediatric disorders. Pediatric osteoarticular diseases have an enormous potential to be treated by MSCs, as severe congenital bone or local cartilage defects, not responding to conventional surgery treatment, might be successfully treated by cellular therapy. Translating basic stem cell research into routine therapies is a complex multistep process which entails the managing of the expected therapeutic benefits with the potential risks in correlation within the existing regulations. Here, we reported the state of art on the use of MSC in skeletal pediatric disorders.

Summary Ex-FABP, extracellular fatty acid binding protein, is a 21 kDa lipocalin expressed in hypertrophic cartilage, muscle and heart during chick embryo development and in granulocytes. Ex-FABP synthesis was increased in chondrocyte and myoblast cultures by inflammatory agents (LPS; IL6) and repressed by antiinflammatory agents. Expression of Ex-FABP and specific gelatinases is paralleled in hypertrophic cartilage; LPS specifically induced high molecular weight gelatinase (>200 kDa). LPS-treated hypertrophic chondrocytes showed increased chemotactic activity for endothelial cells paralleled by increased expression of transferrin. A high amount of Ex-FABP was expressed in adult pathological cartilage both in dyschondroplastic and osteoarthritic chickens. Controls were negative. Ex-FABP could represent a stress protein physiologically expressed in tissues where active remodelling is taking place during development and in tissues characterized by an acute phase response due to pathological conditions. We also suggest that during endochondral bone formation other responses characteristic of a local inflammatory status, such as gelatinase production and angiogenic factor secretion, are “physiologically” activated.

During endochondral bone formation, avascular cartilage differentiates to hypertrophic cartilage that then undergoes erosion and vascularization leading to bone deposition. Resting cartilage produces inhibitors of angiogenesis, shifting to production of angiogenic stimulators in hypertrophic cartilage. A major protein synthesized by hypertrophic cartilage both in vivo and in vitro is transferrin. Here we show that transferrin is a major angiogenic molecule released by hypertrophic cartilage. Endothelial cell migration and invasion is stimulated by transferrins from a number of different sources, including hypertrophic cartilage. Checkerboard analysis demonstrates that transferrin is a chemotactic and chemokinetic molecule. Chondrocyte-conditioned media show similar properties. Polyclonal anti-transferrin antibodies completely block endothelial cell migration and invasion induced by purified transferrin and inhibit the activity produced by hypertrophic chondrocytes by 50–70% as compared with controls. Function-blocking mAbs directed against the transferrin receptor similarly reduce the endothelial migratory response. Chondrocytes differentiating in the presence of serum produce transferrin, whereas those that differentiate in the absence of serum do not. Conditioned media from differentiated chondrocytes not producing transferrin have only 30% of the endothelial cell migratory activity of parallel cultures that synthesize transferrin.The angiogenic activity of transferrins was confirmed by in vivo assays on chicken egg chorioallantoic membrane, showing promotion of neovascularization by transferrins purified from different sources including conditioned culture medium.Based on the above results, we suggest that transferrin is a major angiogenic molecule produced by hypertrophic chondrocytes during endochondral bone formation.

The repair of skeletal defects remains a substantial economic and biomedical burden. The extra-embryonic fetal stem cells derived from amniotic fluid (AFSCs) have been used for the treatment of large bone defects, but mechanisms of repair are not clear. Here we studied the potential contribution of human AFSCs to the modeling of an ectopic bone. We found that AFSCs are not osteogenic in vivo, and, compared to bone marrow-derived stromal cells, recruit more host CD31 and VEGF-R 2 positive cells. Finally, when AFSCs were co-implanted with human-bone forming cells, a normo-osteosynthesis occurred, the engineered ossicle was hyper-vascularized, but AFSCs were not retrieved in the implant within 2 weeks. We concluded that AFSCs do not contribute to the deposition of new bone, but act as a powerful proinflammatory/proangiogenic boost, driving a host response, ending in AFSC clearance and vascularization of the bone environment. In our model, a source of osteocommitted cells, capable to engraft and proliferate in vivo, is needed in order to engineer bone. The angio-attractant properties of AFSCs could be exploited in strategies of endogenous cell homing to actively recruit host progenitors into a predefined anatomic location for in situ bone tissue regeneration.

Summary Objective Studies about cartilage repair in the hip and infant chondrocytes are rare. The aim of our study was to evaluate the use of infant articular hip chondrocytes for tissue engineering of scaffold-assisted cartilage grafts. Method Hip cartilage was obtained from five human donors (age 1–10 years). Expanded chondrocytes were cultured in polyglycolic acid (PGA)-fibrin scaffolds. De- and re-differentiation of chondrocytes were assessed by histological staining and gene expression analysis of typical chondrocytic marker genes. In vivo , cartilage matrix formation was assessed by histology after subcutaneous transplantation of chondrocyte-seeded PGA-fibrin scaffolds in immunocompromised mice. Results The donor tissue was heterogenous showing differentiated articular cartilage and non-differentiated tissue and considerable expression of type I and II collagens. Gene expression analysis showed repression of typical chondrocyte and/or mesenchymal marker genes during cell expansion, while markers were re-induced when expanded cells were cultured in PGA-fibrin scaffolds. Cartilage formation after subcutaneous transplantation of chondrocyte loaded PGA-fibrin scaffolds in nude mice was variable, with grafts showing resorption and host cell infiltration or formation of hyaline cartilage rich in type II collagen. Addition of human platelet rich plasma (PRP) to cartilage grafts resulted robustly in formation of hyaline-like cartilage that showed type II collagen and regions with type X collagen. Conclusion These results suggest that culture of expanded and/or de-differentiated infant hip cartilage cells in PGA-fibrin scaffolds initiates chondrocyte re-differentiation. The heterogenous donor tissue containing immature chondrocytes bears the risk of cartilage repair failure in vivo , which may be possibly overcome by the addition of PRP.

Ovotransferrin expression during chick embryo tibia development has been investigated in vivo by immunocytochemistry and in situ hybridization. Ovotransferrin was first observed in the 7 day cartilaginous rudiment. At later stages, the factor was localized in the articular zone of the bone epiphysis and in the bone diaphysis where it was concentrated in hypertrophic cartilage, in zones of cartilage erosion and in the osteoid at the chondro-bone junction. When the localization of the ovotransferrin receptors was investigated, it was observed that chondrocytes at all stages of differentiation express a low level of the oviduct (tissue) specific receptor. Interestingly, high levels of the receptor were detectable in the 13-d old tibia in the diaphysis collar of stacked-osteoprogenitor cells and in the layer of derived osteoblasts. High levels of oviduct receptor were also observed in the primordia of the menisci. Metabolic labeling of proteins secreted by cultured chondrocytes and osteoblasts and Northern blot analysis of RNA extracted from the same cells confirmed and completed the above information. Ovotransferrin was expressed by in vitro differentiating chondrocytes in the early phase of the culture and, at least when culture conditions allowed extracellular matrix assembly, also by hypertrophic chondrocytes and derived osteoblast-like cells. Osteoblasts directly obtained from bone chips produced ovotransferrin only at the time of culture mineralization. By Western blot analysis, oviduct receptor proteins were detected at a very low level in extract from differentiating and hypertrophic chondrocytes and at a higher level in extract from hypertrophic chondrocytes undergoing differentiation to osteoblast-like cells and from mineralizing osteoblasts. Based on these results, the existence of autocrine and paracrine loops involving ovotransferrin and its receptor during chondrogenesis and endochondral bone formation is discussed.

Bone marrow stimulation techniques in cartilage repair such as drilling are limited by the formation of fibrous to hyaline-like repair tissue. It has been suggested such techniques can be enhanced by covering the defect with scaffolds. We present an innovative approach using a polyglycolic acid (PGA)-hyaluronan scaffold with platelet-rich-plasma (PRP) in drilling.We asked whether (1) PRP immersed in a cell-free PGA-hyaluronan scaffold improves patient-reported 1-year outcomes for the Knee injury and Osteoarthritis Score (KOOS), and (2) implantation of the scaffold in combination with bone marrow stimulation leads to the formation of hyaline-like cartilage repair tissue.We reviewed 52 patients who had arthroscopic implantation of the PGA-hyaluronan scaffold immersed with PRP in articular cartilage defects of the knee pretreated with Pridie drilling. Patients were assessed by KOOS. At 9 months followup, histologic staining was performed in specimens obtained from five patients to assess the repair tissue quality.The KOOS subscores improved for pain (55 to 91), symptoms (57 to 88), activities of daily living (69 to 86), sports and recreation (36 to 70), and quality of life (38 to 73). The histologic evaluation showed a homogeneous hyaline-like cartilage repair tissue.The cell-free PGA-hyaluronan scaffold combined with PRP leads to cartilage repair and improved patient-reported outcomes (KOOS) during 12 months of followup. Histologic sections showed morphologic features of hyaline-like repair tissue. Long-term followup is needed to determine if the cartilage repair tissue is durable.Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Differentiation of hypertrophic chondrocytes toward an osteoblast-like phenotype occurs in vitro when cells are transferred to anchorage-dependent culture conditions in the presence of ascorbic acid (Descalzi Cancedda, F., C. Gentili, P. Manduca, and R. Cancedda. 1992. J. Cell Biol. 117:427-435). This process is enhanced by retinoic acid addition to the culture medium. Here we compare the growth of hypertrophic chondrocytes undergoing this differentiation process to the growth of hypertrophic chondrocytes maintained in suspension culture as such. The proliferation rate is significantly higher in the adherent hypertrophic chondrocytes differentiating to osteoblast-like cells. In cultures supplemented with retinoic acid the proliferation rate is further increased. In both cases cells stop proliferating when mineralization of the extracellular matrix begins. We also report on the ultrastructural organization of the osteoblast-like cell cultures and we show virtual identity with cultures of osteoblasts grown from bone chips. Cells are embedded in a dense meshwork of type I collagen fibers and mineral is observed in the extracellular matrix associated with collagen fibrils. Differentiating hypertrophic chondrocytes secrete large amounts of an 82-kD glycoprotein. The protein has been purified from conditioned medium and identified as ovotransferrin. It is transiently expressed during the in vitro differentiation of hypertrophic chondrocytes into osteoblast-like cells. In cultured hypertrophic chondrocytes treated with 500 nM retinoic acid, ovotransferrin is maximally expressed 3 d after retinoic acid addition, when the cartilage-bone-specific collagen shift occurs, and decays between the 5th and the 10th day, when cells have fully acquired the osteoblast-like phenotype. Similar results were obtained when retinoic acid was added to the culture at the 50 nM "physiological" concentration. Cells expressing ovotransferrin also coexpress ovotransferrin receptors. This suggests an autocrine mechanism in the control of chondrocyte differentiation to osteoblast-like cells.

This chapter is intended to provide a summary of the current materials used in cell encapsulation technology as well as methods for evaluating the performance of cells encapsulated in a polymeric matrix. In particular, it describes the experimental procedure to prepare a hydrogel matrix based on natural polymers for encapsulating and culturing human articular chondrocytes with the interest in cartilage regeneration. Protocols to evaluate the viability, proliferation, differentiation, and matrix production of embedded cells are also described and include standard protocols such as the MTT and [3H] Thymidine assays, reverse transcription polymerase chain reaction (RT-PCR) technique, histology, and immunohistochemistry analysis. The assessment of cell distribution within the 3D hydrogel construct is also described using APoTome analysis.

The mono- and the digalactosyldiacylglycerol (MGDG and DGDG) galactolipids with a high content of polyunsaturated fatty acids, mainly omega-3, have been purified from the thermophilic blue-green alga ETS-05 that colonises the therapeutic thermal mud of Abano and Montegrotto, Italy. The therapeutic thermal mud is applied mostly to osteoarthritic cartilage patients. In the present study, a possible anti-inflammatory function of MGDG in cartilage has been studied in the avian articular cartilage model. We report that, in response to an inflammatory stimulus, adult avian articular cartilage cells express inflammation-related proteins, such as the lipocalin extracellular fatty acid binding protein, Avidin and Serum Amyloid A. The treatment of avian articular chondrocytes with the galactolipid MGDG suppressed the expression of the inflammation-induced proteins, suggesting a strong anti-inflammatory property of MGDG. MGDG has, in addition, a cell anti-proliferative activity, but it does not interfere with cell differentiation, suggesting a protective role for articular cartilage.

We developed a novel injectable carrageenan/fibrin/hyaluronic acid-based hydrogel with in situ gelling properties to be seeded with chondrogenic cells and used for cartilage tissue engineering applications. We first analysed the distribution within the hydrogel construct and the phenotype of human articular chondrocytes (HACs) cultured for 3 weeks in vitro. We observed a statistically significant increase in the cell number during the first 2 weeks and maintenance of cell viability throughout the cell culture, together with the deposition/formation of a cartilage-specific extracellular matrix (ECM). Taking advantage of a new in vivo model that allows the integration between newly formed and preexisting cartilage in immunodeficient mice to be investigated, we showed that injectable hydrogel seeded with human articular chondrocytes was able to regenerate and repair an experimentally made lesion in bovine articular cartilage, thus demonstrating the potential of this novel cell delivery system for cartilage tissue engineering., The authors are grateful to Recco orthopaedic staff members for the collaboration and patients for bioptic material donation as well as to Mrs Daniela Marubbi for histological assistance. This work was supported by funds from the Italian MUR (FIRB-Tissuenet project), the European Union-funded STREP project, HIPPOCRATES (Grant No. NMP3-CT-2003-505758) and the European NoE EXPERTISSUES project (Grant No. NMP3-CT-2004-500283).

Studying cartilage differentiation, we observed the emergence of inflammation-related proteins suggesting that a common pathway was activated in cartilage differentiation and inflammation. In the present paper, we investigated the expression pathway of the inflammation-related enzyme Cyclooxygenase-2 (COX-2) during differentiation and inflammatory response of the chondrocytic cell line MC615. Cells were cultured either as (i) proliferating prechondrogenic cells expressing type I collagen or (ii) differentiated hyperconfluent cells expressing Sox9 and type II collagen. The p38 and the NF-kB pathways were investigated in standard conditions and after inflammatory agents treatment. NF-kB was constitutively activated in differentiated cells. The activation level of NF-kB in differentiated cells was comparable to the level in proliferating cells treated with the inflammatory agent LPS. In both cases, p65 was bound to the NF-kB consensus sequence of COX-2 promoter. p38, constitutively activated in differentiated cells, was activated in proliferating cells by treatment with LPS or IL-1alpha. In stimulated proliferating cells the two pathways are connected since addition of the p38-specific inhibitor SB203580 inhibited p38 activation, significantly reduced NF-kB activation and repressed COX-2 synthesis indicating that p38 is upstream NF-kB activation and COX-2 synthesis. In differentiated cells, the treatment with the inflammatory agent neither enhance NF-kB activation, nor synthesis of COX-2 while the addition of SB203580 neither repressed activation of p38, nor COX-2 synthesis, suggesting a constitutive activation of a p38/NF-kB/COX2 pathway. Our data indicate that in chondrocytes, COX-2 is expressed via p38 activation/NF-kB recruitment during both differentiation and inflammatory response.

Syndecans are single-pass integral membrane components that serve as co-receptors for growth factors and cytokines and can elicit signal transduction via their cytoplasmic tails. We review here previous studies from our groups on syndecan-3 biology and function in the growth plates of developing long bones in chick and mouse embryos. Gain- and loss-of-function data indicate that syndecan-3 has important roles in restricting mitotic activity to the proliferative zone of growth plate and may do so in close cooperation and interaction with the signaling molecule Indian hedgehog (IHH). Biochemical and protein-modeling data suggest a dimeric/oligomeric syndecan-3 configuration on the chondrocyte's cell surface. Analyses of embryos misexpressing syndecan-3 or lacking IHH provide further clues on syndecan-3/IHH interdependence and interrelationships. The data and the conclusions reached provide insights into mechanisms fine-tuning chondrocyte proliferation, maturation, and function in the developing and growing skeleton and into how abnormalities in these fundamental mechanisms may subtend human congenital pathologies, including osteochondromas in hereditary multiple exostoses syndrome.

Ex-FABP is an extracellular fatty acid binding protein, expressed during chicken embryo development in cartilage, muscle fibers, and blood granulocytes. Transfection of chondrocytes and myoblasts with anti-sense Ex-FABP cDNA results in inhibition of cell proliferation and apoptosis induction. Ex-FABP expression is dramatically enhanced by inflammatory stimuli and in pathological conditions. In this paper, by in situ whole mount and immunohistochemistry analysis we show that, at early developmental stage, Ex-FABP is diffuse in all tissues of chick embryos. Particularly high level of transcript and protein are expressed in the heart. During acute phase response (APR) induced by endotoxin LPS injection, a marked increase of Ex-FABP mRNA was observed in embryos, highest Ex-FABP expression being in heart and liver. To investigate in vivo the biological role of Ex-FABP, we have directly microinjected chicken embryos with antibody against Ex-FABP. Almost 70% of chicken embryos died and the target tissue was the heart. We detected in heart of the treated embryos a significant increase of apoptotic cells and high level of fatty acids. We propose that the accumulation of fatty acid, specific ligand of Ex-FABP, in the cell microenvironment is responsible of heart cell death, and we suggest that Ex-FABP may act as a survival protein by playing a role as scavenger for fatty acids.

Cholesterol is required for chondrocyte differentiation and bone formation. Apolipoprotein A1 (apoA-1) plays a major role in lipoprotein clearance and cholesterol redistribution. We report here that apoA-1 is expressed during chondrocyte differentiation in vitro and in vivo. In differentiating chondrocytes, the expression of the liver X receptor (LXR) is modulated and its expression correlates to the expression of apoA-1. The expression of other LXR target genes related to cholesterol homeostasis such as ABCA1 cholesterol transporter and sterol regulatory element-binding protein 1 (SREBP1) is similarly regulated. Small molecule ligands activating either LXR or retinoid X receptor (RXR) lead to a dramatic increase in apoA-1 mRNA and protein expression in cultured chondrocytes. These ligands strongly induce ABCA1 cholesterol transporter expression and effectively mediate cholesterol efflux from hypertrophic chondrocytes. In addition, we report that, in the same cells, the ligands down modulate Serum Amyloid A expression induced by bacterial lipopolysaccharide. Our studies provide evidence that LXR/RXR mediate a fine regulation of cholesterol homeostasis in differentiating chondrocytes.

Hedgehog proteins exert critical roles in embryogenesis and require heparan sulfate proteoglycans (HS-PGs) for action. Indian hedgehog (Ihh) is produced by prehypertrophic chondrocytes in developing long bones and regulates chondrocyte proliferation and other events, but it is not known whether it requires HS-PGs for function. Because the HS-PG syndecan-3 is preferentially expressed by proliferating chondrocytes, we tested whether it mediates Ihh action. Primary chick chondrocyte cultures were treated with recombinant Ihh (rIhh-N) in absence or presence of heparinase I or syndecan-3 neutralizing antibodies. While rIhh-N stimulated proliferation in control cultures, it failed to do so in heparinase- or antibody-treated cultures. In reciprocal gain-of-function studies, chondrocytes were made to overexpress syndecan-3 by an RCAS viral vector. Cells became more responsive to rIhh-N, but even this response was counteracted by heparinase or antibody treatment. To complement the in vitro data, RCAS viral particles were microinjected in day 4–5 chick wing buds and effects of syndecan-3 misexpression were monitored over time. Syndecan-3 misexpression led to widespread chondrocyte proliferation and, interestingly, broader expression and distribution of Ihh. In addition, the syndecan-3 misexpressing skeletal elements were short, remained cartilaginous, lacked osteogenesis, and exhibited a markedly reduced expression of collagen X and osteopontin, products characteristic of hypertrophic chondrocytes and bone cells. The data are the first to indicate that Ihh action in chondrocyte proliferation involves syndecan-3 and to identify a specific member of the syndecan family as mediator of hedgehog function. Developmental Dynamics 229:607–617, 2004. © 2004 Wiley-Liss, Inc.

Long bone formation is a complex process that has been studied for decades (1–3). It initiates with the emergence, at specific times and sites, of mesenchymal cell condensations that are patterned by the concerted action of the zone of polarizing activity (ZPA), apical ectodermal ridge, and dorsal ectoderm. The condensed cells differentiate into chondrocytes that produce characteristic cartilage matrix components and give rise to readily identifiable cartilaginous elements. The chondrocytes within each element start a process of maturation, which includes a proliferative, prehypertrophic, hypertrophic, and post-hypertrophic phase, and become organized in growth plates. At the same time, diarthrodial synovial joints develop at each epiphyseal end. Once formed, hypertrophic cartilage is invaded by bone, marrow, and vascular progenitor cells from adjacent perichondrial tissues, is eroded, and is finally replaced by endochondral bone and marrow. In addition, perichondrial cells give rise to an intramembranous bone collar surrounding the elements, which is critical to determine diameter and shape of the shaft (1).Maturation, hypertrophy, blood vessel invasion, and ossification first occur in the diaphyseal region and then spread toward the opposing epiphyses with increasing developmental time. Thus, long bone formation requires multiple and topographically restricted events within the cartilaginous elements as well as coordinated events in perichondrial tissues. It is not fully understood how all these processes are set and regulated, what signaling molecules mediate cartilage-perichondrium communication and interactions, and how events in cartilage are coordinated with those in perichondrium.

Extracellular Fatty Acid Binding Protein (Ex-FABP) is a 21 kDa lipocalin, expressed during chicken embryo development in hypertrophic cartilage, in muscle fibres and in blood granulocyte. The protein selectively binds with high affinity fatty acids, preferably long chain unsaturated fatty acids in chondrocyte and myoblast cultures Ex-FABP expression is increased by inflammatory-agents and repressed by anti-inflammatory-agents. In adult cartilage, Ex-FABP is expressed only in pathological conditions such as in dyschondroplastic and osteoarthritic chicken cartilage. We propose that lipocalin Ex-FABP represents a stress protein physiologically expressed in tissues where active remodelling is taking place during development and also present in tissues characterized by a stress response due to pathological conditions.