CD105 promotes chondrogenesis of synovium-derived mesenchymal stem cells through Smad2 signaling

Constructing a cross-tissue human knee single-cell atlas identified osteoarthritis reduces regenerative tissue stem cells while increasing inflammatory pain macrophages

Osteoarthritis (OA) affects the entire knee joint; however, cross-tissue molecular mechanisms are poorly understood due to a lack of comprehensive, integrated analysis. We constructed the first comprehensive single-cell RNA sequencing knee OA atlas from articular cartilage, meniscus, synovium, and subchondral bone which showed active communication between them. Healthy synovium and meniscus contain the largest populations of tissue stem cells (TSCs) and immune cells that are altered in OA. The regenerative TSCs expressing SDF1, SOX9, CD146, PDGFRB, and CD105 decrease during OA, whereas osteogenic TSCs expressing osteogenic differentiation-related factor NT5E (CD73) are increased. In OA, the balance between regenerative and osteogenic TSCs shifts in the OA state with an increased number of osteogenic TSCs. We also report an increased level of quadruple-positive inflammatory (IL1B-IL6-NOS2-TNF) and pain marker (P2RX7) specific macrophages in OA. Fibroblasts are enriched in OA-synovium and may contribute to fibrosis. Importantly, OA cartilage contains unique MMP13-producing detrimental chondrocytes along with RUNX2-producing chondrocytes that worsen OA pathophysiology. This atlas provides a novel avenue for potential therapeutic applications in human knee OA and other musculoskeletal diseases and injuries, targeting synovium and meniscus to intervene in OA-specific molecular and cellular alterations.

Current perspectives on the dynamic culture of mesenchymal stromal/stem cell spheroids

Mesenchymal stromal/stem cells (MSCs) are promising candidates for regenerative medicine owing to their self-renewal properties, multilineage differentiation, immunomodulatory effects, and angiogenic potential. MSC spheroids fabricated by 3D culture have recently shown enhanced therapeutic potential. MSC spheroids create a specialized niche with tight cell-cell and cell-extracellular matrix interactions, optimizing their cellular function by mimicking the in vivo environment. Methods for 3D cultivation of MSCs can be classified into 2 main forms: static suspension culture and dynamic suspension culture. Numerous studies have reported the beneficial influence of these methods on MSCs, which is displayed by increased differentiation, angiogenic, immunomodulatory, and anti-apoptotic effects, and stemness of MSC spheroids. Particularly, recent studies highlighted the benefits of dynamic suspension cultures of the MSC spheroids in terms of faster and more compact spheroid formation and the long-term maintenance of stemness properties. However, only a few studies have compared the behavior of MSC spheroids formed using static and dynamic suspension cultures, considering the significant differences between their culture conditions. This review summarizes the differences between static and dynamic suspension culture methods and discusses the biological outcomes of MSC spheroids reported in the literature. In particular, we highlight the advantages of the dynamic suspension culture of MSC spheroids and contemplate its future applications for various diseases.

Revolutionizing bone defect healing: the power of mesenchymal stem cells as seeds

Bone defects can arise from trauma or pathological factors, resulting in compromised bone integrity and the loss or absence of bone tissue. As we are all aware, repairing bone defects is a core problem in bone tissue engineering. While minor bone defects can self-repair if the periosteum remains intact and normal osteogenesis occurs, significant defects or conditions such as congenital osteogenesis imperfecta present substantial challenges to self-healing. As research on mesenchymal stem cell (MSC) advances, new fields of application have emerged; however, their application in orthopedics remains one of the most established and clinically valuable directions. This review aims to provide a comprehensive overview of the research progress regarding MSCs in the treatment of diverse bone defects. MSCs, as multipotent stem cells, offer significant advantages due to their immunomodulatory properties and ability to undergo osteogenic differentiation. The review will encompass the characteristics of MSCs within the osteogenic microenvironment and summarize the research progress of MSCs in different types of bone defects, ranging from their fundamental characteristics and animal studies to clinical applications.

Ganoderma spore lipid ameliorates docetaxel, cisplatin, and 5-fluorouracil chemotherapy-induced damage to bone marrow mesenchymal stem cells and hematopoiesis

BACKGROUND

A triplet chemotherapy regimen of docetaxel, cisplatin, and 5-fluorouracil (TPF) is used to treat head and neck squamous cell carcinoma; however, it is toxic to bone marrow mesenchymal stem cells (BMSCs). We previously demonstrated that Ganoderma spore lipid (GSL) protect BMSCs against cyclophosphamide toxicity. In this study, we investigated the protective effects of GSL against TPF-induced BMSCs and hematopoietic damage.

METHODS

BMSCs and C57BL/6 mice were divided into control, TPF, co-treatment (simultaneously treated with GSL and TPF for 2 days), and pre-treatment (treated with GSL for 7 days before 2 days of TPF treatment) groups. In vitro, morphology, phenotype, proliferation, senescence, apoptosis, reactive oxygen species (ROS), and differentiation of BMSCs were evaluated. In vivo, peripheral platelets (PLTs) and white blood cells (WBCs) from mouse venous blood were quantified. Bone marrow cells were isolated for hematopoietic colony-forming examination.

RESULTS

In vitro, GSL significantly alleviated TPF-induced damage to BMSCs compared with the TPF group, recovering their morphology, phenotype, proliferation, and differentiation capacity (p < 0.05). Annexin V/PI and senescence-associated β-galactosidase staining showed that GSL inhibited apoptosis and delayed senescence in TPF-treated BMSCs (p < 0.05). GSL downregulated the expression of caspase-3 and reduced ROS formation (p < 0.05). In vivo, GSL restored the number of peripheral PLTs and WBCs and protected the colony-forming capacity of bone marrow cells (p < 0.05).

CONCLUSIONS

GSL efficiently protected BMSCs from damage caused by TPF and recovered hematopoiesis.

Stem Cells Derived from Human Exfoliated Deciduous Teeth Functional Assessment: Exploring the Changes of Free Fatty Acids Composition during Cultivation

The metabolic regulation of stemness is widely recognized as a crucial factor in determining the fate of stem cells. When transferred to a stimulating and nutrient-rich environment, mesenchymal stem cells (MSCs) undergo rapid proliferation, accompanied by a change in protein expression and a significant reconfiguration of central energy metabolism. This metabolic shift, from quiescence to metabolically active cells, can lead to an increase in the proportion of senescent cells and limit their regenerative potential. In this study, MSCs from human exfoliated deciduous teeth (SHEDs) were isolated and expanded in vitro for up to 10 passages. Immunophenotypic analysis, growth kinetics, in vitro plasticity, fatty acid content, and autophagic capacity were assessed throughout cultivation to evaluate the functional characteristics of SHEDs. Our findings revealed that SHEDs exhibit distinctive patterns of cell surface marker expression, possess high self-renewal capacity, and have a unique potential for neurogenic differentiation. Aged SHEDs exhibited lower proliferation rates, reduced potential for chondrogenic and osteogenic differentiation, an increasing capacity for adipogenic differentiation, and decreased autophagic potential. Prolonged cultivation of SHEDs resulted in changes in fatty acid composition, signaling a transition from anti-inflammatory to proinflammatory pathways. This underscores the intricate connection between metabolic regulation, stemness, and aging, crucial for optimizing therapeutic applications.

GSTT1 as a Predictive Marker and Enhancer for Osteogenic Potential of Human Adipose-Derived Stromal/Stem Cells

Adipose-derived stromal/stem cells (ASCs) have been extensively studied as cell sources for regenerative medicine for bone because of their excellent proliferative capacity and the ability to obtain a large number of cells with minimal donor morbidity. On the other hand, the differentiation potential of ASCs is generally lower than that of bone marrow-derived stromal/stem cells and varies greatly depending on donors. In this study, we mined a marker that can predict the osteogenic potential of ASC clones and also investigated the usefulness of the molecule as the enhancer of osteogenic differentiation of ASCs as well as its mechanism of action. Through RNA-seq gene analysis, we discovered that GSTT1 (Glutathione S-transferase theta-1) was the most distinguished gene marker between highly osteogenic and poorly osteogenic ASC clones. Knockdown of GSTT1 in high osteogenic ASCs by siGSTT1 treatment reduced mineralized matrix formation. On the other hand, GSTT1 overexpression by GSTT1 transfection or GSTT1 recombinant protein treatment enhanced osteogenic differentiation of low osteogenic ASCs. Metabolomic analysis confirmed significant changes of metabolites related to bone differentiation in ASCs transfected with GSTT1. A high total antioxidant capacity, low levels of cellular reactive oxygen species, and increased GSH/GSSG ratios were also detected in GSTT1-transfected ASCs. When the in vivo effect of GSTT1-transfected ASCs on bone regeneration was investigated with segmental long-bone defect model in rats, bone regeneration was significantly better after implantation of GSTT1-transfected ASCs compared with that of control vector-transfected ASCs. In conclusion, GSTT1 can be a useful marker to screen the highly osteogenic ASC clones and also a therapeutic factor to enhance the osteogenic differentiation of poorly osteogenic ASC clones. © 2023 American Society for Bone and Mineral Research (ASBMR).

Comparative Analysis of Porcine Adipose- and Wharton's Jelly-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are promising candidates for tissue regeneration, cell therapy, and cultured meat research owing to their ability to differentiate into various lineages including adipocytes, chondrocytes, and osteocytes. As MSCs display different characteristics depending on the tissue of origin, the appropriate cells need to be selected according to the purpose of the research. However, little is known of the unique properties of MSCs in pigs. In this study, we compared two types of porcine mesenchymal stem cells (MSCs) isolated from the dorsal subcutaneous adipose tissue (adipose-derived stem cells (ADSCs)) and Wharton's jelly of the umbilical cord (Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs)) of 1-day-old piglets. The ADSCs displayed a higher proliferation rate and more efficient differentiation potential into adipogenic and chondrogenic lineages than that of WJ-MSCs; conversely, WJ-MSCs showed superior differentiation capacity towards osteogenic lineages. In early passages, ADSCs displayed higher proliferation rates and mitochondrial energy metabolism (measured based on the oxygen consumption rate) compared with that of WJ-MSCs, although these distinctions diminished in late passages. This study broadens our understanding of porcine MSCs and provides insights into their potential applications in animal clinics and cultured meat science.

Temporomandibular Joint Fibrocartilage Contains CD105 Positive Mouse Mesenchymal Stem/Progenitor Cells with Increased Chondrogenic Potential

Objective

A specific type of mesenchymal stem/progenitor cells (MSPCs), CD105+ is reported to aid in cartilage regeneration through TGF-β/Smad2-signalling. The purpose of this study was to identify and characterize CD105+ MSPCs in temporomandibular joint (TMJ) cartilage.

Materials and Methods

MSPCs were isolated from mouse TMJ condyle explants and evaluated for their clonogenicity and pluripotential abilities. MSPC were examined for CD105 antigen using immunohistochemistry and flow cytometry.

Results

Immunohistochemistry revealed presence of CD105+ MSPCs in the proliferative zone of condyle's cartilage. Only 0.2% of isolated MSPCs exhibited CD105, along with the stem cell surface markers CD44 and Sca-1. In CD105+ MSPCs, intracellular immunostaining revealed significantly higher (p < 0.05) protein levels of collagen type 1, 2, proteoglycan 4. Ability for chondrogenic differentiation was found to be significantly higher (p < 0.05) after 4 weeks compared to CD105- cells, using alcian blue staining. CD105+ cells were found to resemble an early MSPC subgroup with significantly higher gene expression of biglycan, proteoglycan 4, collagen type 2, Gli2, Sox5 (p < 0.001) and Sox9 (p < 0.05). In contrast, significantly lower levels of Runx2 (p < 0.05), Osterix, Trps1, Col10a1 (p < 0.01), Ihh (p < 0.001) related to chondrocyte senescence and commitment to osteogenic lineage, were observed compared to CD105- cells.

Conclusion

The study showed the existence of a CD105+ MSPC subgroup within TMJ fibrocartilage that may be activated to aid in fibrocartilage repair.

Managing the Heterogeneity of Mesenchymal Stem Cells for Cartilage Regenerative Therapy: A Review

Articular cartilage defects commonly result from trauma and are associated with significant morbidity. Since cartilage is an avascular, aneural, and alymphatic tissue with a poor intrinsic healing ability, the regeneration of functional hyaline cartilage remains a difficult clinical problem. Mesenchymal stem cells (MSCs) are multipotent cells with multilineage differentiation potential, including the ability to differentiate into chondrocytes. Due to their availability and ease of ex vivo expansion, clinicians are increasingly applying MSCs in the treatment of cartilage lesions. However, despite encouraging pre-clinical and clinical data, inconsistencies in MSC proliferative and chondrogenic potential depending on donor, tissue source, cell subset, culture conditions, and handling techniques remain a key barrier to widespread clinical application of MSC therapy in cartilage regeneration. In this review, we highlight the strategies to manage the heterogeneity of MSCs ex vivo for more effective cartilage repair, including reducing the MSC culture expansion period, and selecting MSCs with higher chondrogenic potential through specific genetic markers, surface markers, and biophysical attributes. The accomplishment of a less heterogeneous population of culture-expanded MSCs may improve the scalability, reproducibility, and standardisation of MSC therapy for clinical application in cartilage regeneration.

Differences in the intrinsic chondrogenic potential of human mesenchymal stromal cells and iPSC-derived multipotent cells

BACKGROUND

Human multipotent progenitor cells (hiMPCs) created from induced pluripotent stem cells (iPSCs) represent a new cell source for cartilage regeneration. In most studies, bone morphogenetic proteins (BMPs) are needed to enhance transforming growth factor-β (TGFβ)-induced hiMPC chondrogenesis. In contrast, TGFβ alone is sufficient to result in robust chondrogenesis of human primary mesenchymal stromal cells (hMSCs). Currently, the mechanism underlying this difference between hiMPCs and hMSCs has not been fully understood.

METHODS

In this study, we first tested different growth factors alone or in combination in stimulating hiMPC chondrogenesis, with a special focus on chondrocytic hypertrophy. The reparative capacity of hiMPCs-derived cartilage was assessed in an osteochondral defect model created in rats. hMSCs isolated from bone marrow were included in all studies as the control. Lastly, a mechanistic study was conducted to understand why hiMPCs and hMSCs behave differently in responding to TGFβ.

RESULTS

Chondrogenic medium supplemented with TGFβ3 and BMP6 led to robust in vitro cartilage formation from hiMPCs with minimal hypertrophy. Cartilage tissue generated from this new method was resistant to osteogenic transition upon subcutaneous implantation and resulted in a hyaline cartilage-like regeneration in osteochondral defects in rats. Interestingly, TGFβ3 induced phosphorylation of both Smad2/3 and Smad1/5 in hMSCs, but only activated Smad2/3 in hiMPCs. Supplementing BMP6 activated Smad1/5 and significantly enhanced TGFβ's compacity in inducing hiMPC chondrogenesis. The chondro-promoting function of BMP6 was abolished by the treatment of a BMP pathway inhibitor.

CONCLUSIONS

This study describes a robust method to generate chondrocytes from hiMPCs with low hypertrophy for hyaline cartilage repair, as well as elucidates the difference between hMSCs and hiMPCs in response to TGFβ. Our results also indicated the importance of activating both Smad2/3 and Smad1/5 in the initiation of chondrogenesis.

A Comparative Study of Canine Mesenchymal Stem Cells Isolated from Different Sources

In this study, we provide comprehensive analyses of mesenchymal stem cells (MSCs) isolated from three types of canine tissues: bone marrow (BM-MSCs), adipose tissue (AT-MSCs) and amniotic tissue (AM-MSCs). We compare their morphology, phenotype, multilineage potential and proliferation activity. The BM-MSCs and AM-MSCs showed fibroblast-like shapes against the spindle shape of the AT-MSCs. All populations showed strong osteogenic and chondrogenic potential. However, we observed phenotypic differences. The BM-MSCs and AT-MSCs revealed high expression of CD29, CD44, CD90 and CD105 positivity compared to the AM-MSCs, which showed reduced expression of all the analysed CD markers. Similarly, the isolation yield and proliferation varied depending on the source. The highest isolation yield and proliferation were detected in the population of AT-MSCs, while the AM-MSCs showed a high yield of cells, but the lowest proliferation activity, in contrast to the BM-MSCs which had the lowest isolation yield. Thus, the present data provide assumptions for obtaining a homogeneous MSC derived from all three canine tissues for possible applications in veterinary regenerative medicine, while the origin of isolated MSCs must always be taken into account.

Migratory chondroprogenitors retain superior intrinsic chondrogenic potential for regenerative cartilage repair as compared to human fibronectin derived chondroprogenitors

Cell-based therapy for articular hyaline cartilage regeneration predominantly involves the use of mesenchymal stem cells and chondrocytes. However, the regenerated repair tissue is suboptimal due to the formation of mixed hyaline and fibrocartilage, resulting in inferior long-term functional outcomes. Current preclinical research points towards the potential use of cartilage-derived chondroprogenitors as a viable option for cartilage healing. Fibronectin adhesion assay-derived chondroprogenitors (FAA-CP) and migratory chondroprogenitors (MCP) exhibit features suitable for neocartilage formation but are isolated using distinct protocols. In order to assess superiority between the two cell groups, this study was the first attempt to compare human FAA-CPs with MCPs in normoxic and hypoxic culture conditions, investigating their growth characteristics, surface marker profile and trilineage potency. Their chondrogenic potential was assessed using mRNA expression for markers of chondrogenesis and hypertrophy, glycosaminoglycan content (GAG), and histological staining. MCPs displayed lower levels of hypertrophy markers (RUNX2 and COL1A1), with normoxia-MCP exhibiting significantly higher levels of chondrogenic markers (Aggrecan and COL2A1/COL1A1 ratio), thus showing superior potential towards cartilage repair. Upon chondrogenic induction, normoxia-MCPs also showed significantly higher levels of GAG/DNA with stronger staining. Focused research using MCPs is required as they can be suitable contenders for the generation of hyaline-like repair tissue.

The Identification of Marker Genes for Predicting the Osteogenic Differentiation Potential of Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have the potential to differentiate into a variety of mature cell types and are a promising source of regenerative medicine. The success of regenerative medicine using MSCs strongly depends on their differentiation potential. In this study, we sought to identify marker genes for predicting the osteogenic differentiation potential by comparing ilium MSC and fibroblast samples. We measured the mRNA levels of 95 candidate genes in nine ilium MSC and four fibroblast samples before osteogenic induction, and compared them with alkaline phosphatase (ALP) activity as a marker of osteogenic differentiation after induction. We identified 17 genes whose mRNA expression levels positively correlated with ALP activity. The chondrogenic and adipogenic differentiation potentials of jaw MSCs are much lower than those of ilium MSCs, although the osteogenic differentiation potential of jaw MSCs is comparable with that of ilium MSCs. To select markers suitable for predicting the osteogenic differentiation potential, we compared the mRNA levels of the 17 genes in ilium MSCs with those in jaw MSCs. The levels of 7 out of the 17 genes were not substantially different between the jaw and ilium MSCs, while the remaining 10 genes were expressed at significantly lower levels in jaw MSCs than in ilium MSCs. The mRNA levels of the seven similarly expressed genes were also compared with those in fibroblasts, which have little or no osteogenic differentiation potential. Among the seven genes, the mRNA levels of IGF1 and SRGN in all MSCs examined were higher than those in any of the fibroblasts. These results suggest that measuring the mRNA levels of IGF1 and SRGN before osteogenic induction will provide useful information for selecting competent MSCs for regenerative medicine, although the effectiveness of the markers is needed to be confirmed using a large number of MSCs, which have various levels of osteogenic differentiation potential.

Chondrogenic Characteristics of Auricular Chondrocytes Cocultured With Adipose-Derived Stem Cells are Superior to Stromal Vascular Fraction of Adipose Tissue

ABSTRACT

Reconstruction of craniofacial cartilage defects is among the most challenging operations in facial plastic surgery. The co-culture system of partial replacement of chondrocytes by stem cells has been confirmed effective in the repair of cartilaginous defects. The aim of this study is to compare chondrogenic properties of expanded adipose-derived stem cells (ADSCs) and stromal vascular fraction (SVF), including ADSCs/SVF monoculture and coculture with rabbit auricular chondrocytes (ACs). Analysis of morphology, histology, real-time polymerase chain reaction and glycosaminoglycans (GAG) quantification were performed to characterize the chondrogenesis of pellets. The triple differentiation potential of ADSCs had been confirmed. Further, using flow cytometry, the authors demonstrated that ADSCs and SVF have different characteristics in cell surface markers, and ADSCs are more enriched in cells from the mesenchymal lineage than SVF. GAG production of ADSCs is significantly higher than that of SVF in pellet monoculture, and pellet coculture of ADSCs and ACs are better in depositing cartilage matrix than the mixture of SVF and ACs. Our study suggests that ADSCs may be more suitable seed cells for craniofacial cartilage defect or deformity repair.

Biological Aspects and Clinical Applications of Mesenchymal Stem Cells: Key Features You Need to be Aware of

Mesenchymal Stem Cells (MSCs), a form of adult stem cells, are known to have a selfrenewing property and the potential to specialize into a multitude of cells and tissues such as adipocytes, cartilage cells, and fibroblasts. MSCs can migrate and home to the desired target zone where inflammation is present. The unique characteristics of MSCs in repairing, differentiation, regeneration, and the high capacity of immune modulation have attracted tremendous attention for exerting them in clinical purposes, as they contribute to the tissue regeneration process and anti-tumor activity. The MSCs-based treatment has demonstrated remarkable applicability towards various diseases such as heart and bone malignancies, and cancer cells. Importantly, genetically engineered MSCs, as a stateof- the-art therapeutic approach, could address some clinical hurdles by systemic secretion of cytokines and other agents with a short half-life and high toxicity. Therefore, understanding the biological aspects and the characteristics of MSCs is an imperative issue of concern. Herein, we provide an overview of the therapeutic application and the biological features of MSCs against different inflammatory diseases and cancer cells. We further shed light on MSCs' physiological interaction, such as migration, homing, and tissue repairing mechanisms in different healthy and inflamed tissues.

Endoglin in the Spotlight to Treat Cancer

A spotlight has been shone on endoglin in recent years due to that fact of its potential to serve as both a reliable disease biomarker and a therapeutic target. Indeed, endoglin has now been assigned many roles in both physiological and pathological processes. From a molecular point of view, endoglin mainly acts as a co-receptor in the canonical TGFβ pathway, but also it may be shed and released from the membrane, giving rise to the soluble form, which also plays important roles in cell signaling. In cancer, in particular, endoglin may contribute to either an oncogenic or a non-oncogenic phenotype depending on the cell context. The fact that endoglin is expressed by neoplastic and non-neoplastic cells within the tumor microenvironment suggests new possibilities for targeted therapies. Here, we aimed to review and discuss the many roles played by endoglin in different tumor types, as well as the strong evidence provided by pre-clinical and clinical studies that supports the therapeutic targeting of endoglin as a novel clinical strategy.

Recent Developed Strategies for Enhancing Chondrogenic Differentiation of MSC: Impact on MSC-Based Therapy for Cartilage Regeneration

Articular cartilage is susceptible to damage, but its self-repair is hindered by its avascular nature. Traditional treatment methods are not able to achieve satisfactory repair effects, and the development of tissue engineering techniques has shed new light on cartilage regeneration. Mesenchymal stem cells (MSCs) are one of the most commonly used seed cells in cartilage tissue engineering. However, MSCs tend to lose their multipotency, and the composition and structure of cartilage-like tissues formed by MSCs are far from those of native cartilage. Thus, there is an urgent need to develop strategies that promote MSC chondrogenic differentiation to give rise to durable and phenotypically correct regenerated cartilage. This review provides an overview of recent advances in enhancement strategies for MSC chondrogenic differentiation, including optimization of bioactive factors, culture conditions, cell type selection, coculture, gene editing, scaffolds, and physical stimulation. This review will aid the further understanding of the MSC chondrogenic differentiation process and enable improvement of MSC-based cartilage tissue engineering.

Heterogeneity of mesenchymal stem cells in cartilage regeneration: from characterization to application

Articular cartilage is susceptible to damage but hard to self-repair due to its avascular nature. Traditional treatment methods are not able to produce satisfactory effects. Mesenchymal stem cells (MSCs) have shown great promise in cartilage repair. However, the therapeutic effect of MSCs is often unstable partly due to their heterogeneity. Understanding the heterogeneity of MSCs and the potential of different types of MSCs for cartilage regeneration will facilitate the selection of superior MSCs for treating cartilage damage. This review provides an overview of the heterogeneity of MSCs at the donor, tissue source and cell immunophenotype levels, including their cytological properties, such as their ability for proliferation, chondrogenic differentiation and immunoregulation, as well as their current applications in cartilage regeneration. This information will improve the precision of MSC-based therapeutic strategies, thus maximizing the efficiency of articular cartilage repair.

[The role of CD146 in mesenchymal stem cells]

Objective

To summarize the expression and role of CD146 in mesenchymal stem cells (MSCs).

Methods

The literature related to CD146 at home and abroad were extensively consulted, and the CD146 expression in MSCs and its function were summarized and analyzed.

Results

CD146 is a transmembrane protein that mediates the adhesion of cells to cells and extracellular matrix, and is expressed on the surface of various MSCs. More and more studies have shown that CD146 ⁺ MSCs have superior cell properties such as greater proliferation, differentiation, migration, and immune regulation abilities than CD146 ^- or unsorted MSCs, and the application of CD146 ⁺ MSCs in the treatment of specific diseases has also achieved better results. CD146 is also involved in mediating a variety of cellular signaling pathways, but whether it plays the same role in MSCs remains to be demonstrated by further experiments.

Conclusion

The utilization of CD146 ⁺ MSCs for tissue regeneration will be conducive to improving the therapeutic effect of MSCs.

Endoglin Level Is Critical for Cartilage Tissue Formation In Vitro by Passaged Human Chondrocytes

Transforming growth factor beta (TGFβ) signaling is required for in vitro chondrogenesis. In animal models of osteoarthritis (OA), TGFβ receptor alterations are detected in chondrocytes in severe OA cartilage. It is not known whether such changes are dependent on the grade of human OA and if they affect chondrogenesis. Thus, the purpose of this study was to determine if human OA chondrocytes obtained from low-grade or high-grade disease could form cartilage tissue and to assess the role of the co-receptors, endoglin (ENG) and TGFβ receptor 3 (TGFBRIII), in the regulation of this tissue generation in vitro. We hypothesized that the grade of OA disease would not affect the ability of cells to form cartilage tissue and that the TGFβ co-receptor, ENG, would be critical to regulating tissue formation. Chondrocytes isolated from low-grade OA or high-grade OA human articular cartilage (AC) were analyzed directly (P0) or passaged in monolayer to P2. Expression of the primary TGFβ receptor ALK5, and the co-receptors ENG and TGFβRIII, was assessed by image flow cytometry. To assess the ability to form cartilaginous tissue, cells were placed in three-dimensional culture at high density and cultured in chondrogenic media containing TGFβ3. ENG knockdown was used to determine its role in regulating tissue formation. Overall, grade-specific differences in expression of ALK5, ENG, and TGFβRIII in primary or passaged chondrocytes were not detected; however, ENG expression increased significantly after passaging. Despite the presence of ALK5, P0 cells did not form cartilaginous tissue. In contrast, P2 cells derived from low-grade and high-grade OA AC formed hyaline-like cartilaginous tissues of similar quality. Knockdown of ENG in P2 cells inhibited cartilaginous tissue formation compared to controls indicating that the level of ENG protein expression is critical for in vitro chondrogenesis by passaged articular chondrocytes. This study demonstrates that it is not the grade of OA, but the levels of ENG in the presence of ALK5 that influences the ability of human passaged articular chondrocytes to form cartilaginous tissue in vitro in 3D culture. This has implications for cartilage repair therapies. Impact statement These findings are important clinically, given the limited availability of osteoarthritis (OA) cartilage tissue. Being able to use cells from all grades of OA will increase our ability to obtain sufficient cells for cartilage repair. In addition, it is possible that endoglin (ENG) levels, in the presence of ALK5 expression, may be suitable to use as biomarkers to identify cells able to produce cartilage.

Mesenchymal stem cell markers in periodontal tissues and periapical lesions

INTRODUCTION

Mesenchymal stem cells (MSCs) are characterized by the potential to differentiate into multiple cell lineages, high proliferation rates, and self-renewal capacity, in addition to the ability to maintain their undifferentiated state. These cells have been identified in physiological oral tissues such as pulp tissue, dental follicle, apical papilla and periodontal ligament, as well as in pathological situations such as chronic periapical lesions (CPLs). The criteria used for the identification of MSCs include the positive expression of specific surface antigens, with CD73, CD90, CD105, CD44, CD146, STRO-1, CD166, NANOG and OCT4 being the most specific for these cells.

AIM

The aim of this review was to explore the literature on markers able to identify MSCs as well as the presence of these cells in the healthy periodontal ligament and CPLs, highlighting their role in regenerative medicine and implications in the progression of these lesions.

METHODS

Narrative literature review searching the PubMed and Medline databases. Articles published in English between 1974 and 2020 were retrieved.

CONCLUSION

The included studies confirmed the presence of MSCs in the healthy periodontal ligament and in CPLs. Several surface markers are used for the characterization of these cells which, although not specific, are effective in cell recognition. Mesenchymal stem cells participate in tissue repair, exerting anti- inflammatory, immunosuppressive and proangiogenic effects, and are therefore involved in the progression and attenuation of CPLs or even in the persistence of these lesions.

Intra-Articular Injection of Stromal Cell-Derived Factor 1α Promotes Meniscal Healing via Macrophage and Mesenchymal Stem Cell Accumulation in a Rat Meniscal Defect Model

The stromal-cell-derived factor-1α (SDF-1) is well-known for playing important roles in the regeneration of tissue by enhancing cell migration. However, the effect of SDF-1 in meniscal healing remains unknown. The purpose of this study is to investigate the effects of intra-articular injection of SDF-1 on meniscus healing in a rat meniscal defect model. The intra-articular SDF-1 injection was performed at meniscectomy and one week later. Macroscopic and histological assessments of the reparative meniscus were conducted at one, two and six weeks after meniscectomy in rats. In the macroscopic evaluation, the SDF-1 group showed an increase in the size of the reparative meniscus at six weeks after meniscectomy compared to the phosphate-buffered saline (PBS) injection (no-treatment) group. Histological findings showed that intra-articular injection of SDF-1 enhanced the migration of macrophages to the site of the regenerative meniscus at one and two weeks after meniscectomy. CD68- and CD163-positive cells in the SDF-1 group at one week after meniscectomy were significantly higher than in the no-treatment group. CD163-positive cells in the SDF-1 group at two weeks were significantly higher than in the no-treatment group. At one week after meniscectomy, there were cells expressing mesenchymal-stem-cell-related markers in the SDF-1 group. These results indicate the potential of regenerative healing of the meniscus by SDF-1 injection via macrophage and mesenchymal stem cell accumulation. In the present study, intra-articular administration of SDF-1 contributed to meniscal healing via macrophage, CD90-positive cell and CD105-positive cell accumulation in a rat meniscal defect model. The SDF-1–CXCR4 pathway plays an important role in the meniscal healing process. For potential clinical translation, SDF-1 injection therapy seems to be a promising approach for the biological augmentation in meniscal injury areas to enhance healing capacity.

Injectable double-crosslinked hydrogels with kartogenin-conjugated polyurethane nano-particles and transforming growth factor β3 for in-situ cartilage regeneration

Articular cartilage has a limited ability for self-repair after injury. Implantation of scaffolds functionalized with bioactive molecules that could induce the migration and chondrogenesis of endogenous mesenchymal stem cells (MSCs) provides a convenient alternative for in-situ cartilage regeneration. In this study, we found the synergistic effects of kartogenin (KGN) and transforming growth factor β3 (TGF-β3) on chondrogenesis of MSCs in vitro, indicating that KGN and TGF-β3 are a good match for cartilage regeneration. Furthermore, we confirmed that KGN promoted the chondrogenesis of MSCs through attenuating the degradation of Runx1, which physically interacted with p-Smad3 in nuclei of MSCs. Meanwhile, we designed an injectable double-crosslinked hydrogel with superior mechanical property and longer support for cartilage regeneration by modifying sodium alginate and gelatin. When loaded with KGN conjugated polyurethane nanoparticles (PN-KGN) and TGF-β3, this hydrogel showed biological functions by the release of KGN and TGF-β3, which promoted the MSC migration and cartilage regeneration in one system. In conclusion, the cell-free hydrogel, along with PN-KGN and TGF-β3, provides a promising strategy for cartilage repair by attracting endogenous MSCs and inducing chondrogenesis of recruited cells in a single-step procedure.

Significance of MEF2C and RUNX3 Regulation for Endochondral Differentiation of Human Mesenchymal Progenitor Cells

Guiding progenitor cell development between chondral versus endochondral pathways is still an unachieved task of cartilage neogenesis, and human mesenchymal progenitor cell (MPC) chondrogenesis is considered as a valuable model to better understand hypertrophic development of chondrocytes. Transcription factors Runx2, Runx3, and Mef2c play prominent roles for chondrocyte hypertrophy during mouse development, but little is known on the importance of these key fate-determining factors for endochondral development of human MPCs. The aim of this study was to unravel the regulation of RUNX2, RUNX3, and MEF2C during MPC chondrogenesis, the pathways driving their expression, and the downstream hypertrophic targets affected by their regulation. RUNX2, RUNX3, and MEF2C gene expression was differentially regulated during chondrogenesis of MPCs, but remained low and unregulated when non-hypertrophic articular chondrocytes were differentiated under the same conditions. RUNX3 and MEF2C mRNA and protein levels rose in parallel to hypertrophic marker upregulation, but surprisingly, RUNX2 gene expression changed only by trend and RUNX2 protein remained undetectable. While RUNX3 expression was driven by TGF-β and BMP signaling, MEF2C responded to WNT-, BMP-, and Hedgehog-pathway inhibition. MEF2C but not RUNX3 levels correlated significantly with COL10A1, IHH, and IBSP gene expression when hypertrophy was attenuated. IBSP was a downstream target of RUNX3 and MEF2C but not RUNX2 in SAOS-2 cells, underlining the capacity of RUNX3 and MEF2C to stimulate osteogenic marker expression in human cells. Conclusively, RUNX3 and MEF2C appeared more important than RUNX2 for human endochondral MPC chondrogenesis. Pathways altering the speed of chondrogenesis (FGF, TGF-β, BMP) affected RUNX2 or RUNX3, while pathways changing hypertrophy (WNT, PTHrP/HH) regulated mainly MEF2C. Taken together, reduction of MEF2C levels is a new goal to shift human cartilage neogenesis toward the chondral pathway.

Different culture method changing CD105 expression in amniotic fluid MSCs without affecting differentiation ability or immune function

MSCs are kind of cultured cells that reside in different tissues as inducers or regulators of physiological and pathological processes. Here, we derived MSCs from amniotic fluid and compared their differentiation ability and immunosuppression effect on PHA‐activated PBMC with those of MSCs isolated from umbilical cords. Amniotic fluid MSCs were isolated and cultured on commercial AFC medium and classic MSC medium, and the number and size of colonies were used to evaluate differences in primary and passaged culture. Rate of proliferation, population doubling time, cell morphology, cell surface markers and mRNA expression were measured in subcultured cells. Furthermore, a comparative study was performed with umbilical cord MSCs to assess the ability of differentiation and immunosuppressive effect of PHA‐stimulated PBMCs. Amniotic fluid MSCs were isolated and expanded by three methods, and exhibited nearly all the characteristics of umbilical cord MSCs. Compared with umbilical cord MSCs, amniotic fluid MSCs had an enhanced osteogenic and chrondrogenic differentiation capability, and stronger immunosuppression effect of inhibition of PHA‐activated PBMC division. Culture with commercial AFCs medium yielded the highest percentage of CD105 expression and showed some advantages in primary cell isolation, cell source‐specific marker retention and cell proliferation. We demonstrated that amniotic fluid MSCs exhibited some advantages over umbilical cord MSCs, and different culture media caused cell proliferation, cell surface marker and cell morphology change, but were not associated with varying differentiation capability and immune effects.

The synovial fluid from patients with focal cartilage defects contains mesenchymal stem/stromal cells and macrophages with pro- and anti-inflammatory phenotypes

Objective

The synovial fluid (SF) of patients with focal cartilage defects contains a population of poorly characterised cells that could have pathophysiological implications in early osteoarthritis and joint tissue repair. We have examined the cells within SF of such joints by determining their chondrogenic capacity following culture expansion and establishing the phenotypes of the macrophage subsets in non-cultured cells.

Design

Knee SF cells were obtained from 21 patients receiving cell therapy to treat a focal cartilage defect. Cell surface immunoprofiling for stem cell and putative chondrogenic markers, and the expression analysis of key chondrogenic and hypertrophic genes were conducted on culture-expanded SF cells prior to chondrogenesis. Flow cytometry was also used to determine the macrophage subsets in freshly isolated SF cells.

Results

Immunoprofiling revealed positivity for the monocyte/macrophage marker (CD14), the haematopoietic/endothelial cell marker (CD34) and mesenchymal stem/stromal cell markers (CD73, CD90, CD105) on culture expanded cells. We found strong correlations between the presence of CD14 and the vascular cell adhesion marker, CD106 (r = 0.81, p = 0.003). Collagen type II expression after culture expansion positively correlated with GAG production (r = 0.73, p = 0.006), whereas CD90 (r = -0.6, p = 0.03) and CD105 (r = -0.55, p = 0.04) immunopositivity were inversely related to GAG production. Freshly isolated SF cells were positive for both pro- (CD86) and anti-inflammatory markers (CD163 and CD206).

Conclusions

The cellular content of the SF from patients with focal cartilage injuries is comprised of a heterogeneous population of reparative and inflammatory cells. Additional investigations are needed to understand the role played by these cells in the attempted repair and inflammatory process in diseased joints.

BDNF-overexpressing human mesenchymal stem cells mediate increased neuronal protection in vitro

The use of neurotrophic factors as therapeutic agents for neurodegenerative diseases is considered as an approach aimed at restoring and maintaining neuronal function in the peripheral and central nervous system. Since the neuroprotective effect is depending on chronic delivery of the neurotrophic factors a sustained application, e.g., via cell‐based delivery is necessary. Human mesenchymal stem cells (hMSCs) were lentivirally modified to overexpress brain‐derived neurotrophic factor (BDNF) and to express fluorescent marker genes for easy visualization. Since genetically modified cells should be site‐specifically retained (e.g., by encapsulation) in the patients to avoid adverse effects the cells were additionally differentiated to chondrocytes to hypothetically improve their vitality and survival in a delivery matrix. Different polycations for lentiviral transduction were investigated for their efficiency. The success of differentiation was determined by analysis of chondrocyte marker genes and the neuroprotective effect of BDNF‐overexpressing cells was exemplarily investigated on neurons of the peripheral auditory system. The genetically modified hMSCs overexpressed BDNF from under 1 to 125 ng ml⁻¹ day⁻¹ depending on the donor and transfection method. Using protamine sulfate the transfection efficacy was superior compared to the use of polybrene. The BDNF secreted by the MSCs was significantly neuroprotective in comparison to the relevant controls even though the produced mean concentrations were lower than the effective concentrations for recombinant industrially produced proteins described in literature. The presented system of BDNF‐overexpressing hMSCs is neuroprotective and is therefore considered as a promising method for sustained delivery of proteins in therapeutically relevant amounts to degenerating neuronal structures.

Molecular phenotyping of the surfaceome of migratory chondroprogenitors and mesenchymal stem cells using biotinylation, glycocapture and quantitative LC-MS/MS proteomic analysis

The complement of cell surface proteins, collectively referred to as the surfaceome, is a useful indicator of normal differentiation processes, and the development of pathologies such as osteoarthritis (OA). We employed biochemical and proteomic tools to explore the surfaceome and to define biomarkers in chondrogenic progenitor cells (CPC) derived from human OA knee articular cartilage. These cells have great therapeutic potential, but their unexplored biology limits their clinical application. We performed biotinylation combined with glycocapture and high throughput shotgun proteomics to define the surface proteome of human bone marrow mesenchymal stem cells (MSCs) and human CPCs. We prepared cell surface protein-enriched fractions from MSCs and CPCs, and then a proteomic approach was used to compare and evaluate protein changes between undifferentiated MSCs and CPCs. 1256 proteins were identified in the study, of which 791 (63%) were plasma membrane, cell surface or extracellular matrix proteins. Proteins constituting the surfaceome were annotated and categorized. Our results provide, for the first time, a repository of quantitative proteomic data on the surfaceome of two closely related cell types relevant to cartilage biology and OA. These results may provide novel insights into the transformation of the surfaceome during chondrogenic differentiation and phenotypic changes during OA development.

Genetic Markers Can Predict Chondrogenic Differentiation Potential in Bone Marrow-Derived Mesenchymal Stromal Cells

The precise predictions of the differentiation direction and potential of mesenchymal stromal cells (MSCs) are an important key to the success of regenerative medicine. The expression levels of fate-determining genes may provide tools for predicting differentiation potential. The expression levels of 95 candidate marker genes and glycosaminoglycan (GAG) contents after chondrogenic induction in 10 undifferentiated ilium and 5 jaw MSC cultures were determined, and their correlations were analyzed. The expression levels of eight genes before the induction of chondrogenic MSC differentiation were significantly correlated with the GAG levels after induction. Based on correlation patterns, the eight genes were classified into two groups: group 1 genes (AURKB, E2F1, CDKN2D, LIF, and ACLY), related to cell cycle regulation, and group 2 genes (CD74, EFEMP1, and TGM2), involved in chondrogenesis. The expression levels of the group 2 genes were significantly correlated with the ages of the cell donors. The expression levels of CDKN2D, CD74, and TGM2 were >10-fold higher in highly potent MSCs (ilium MSCs) than in MSCs with limited potential (jaw MSCs). Three-dimensional (3D) scatter plot analyses of the expression levels of these genes showed reduced variability between donors and confirmed predictive potential. These data suggest that group 2 genes are involved in age-dependent decreases in the chondrogenic differentiation potential of MSCs, and combined 3D analyses of the expression profiles of three genes, including two group 2 genes, were predictive of MSC differentiation potential.

TGF-β and mesenchymal stromal cells in regenerative medicine, autoimmunity and cancer

Multipotent mesenchymal stromal cells (MSCs) represent a promising cell-based therapy in regenerative medicine and for the treatment of inflammatory/autoimmune diseases. Importantly, MSCs have emerged as an important contributor to the tumor stroma with both pro- and anti-tumorigenic effects. However, the successful translation of MSCs to the clinic and the prevention of their tumorigenic and metastatic effect require a greater understanding of factors controlling their proliferation, differentiation, migration and immunomodulation in vitro and in vivo. The transforming growth factor(TGF)-β1, 2 and 3 are involved in almost every aspect of MSC function. The aim of this review is to highlight the roles that TGF-β play in the biology and therapeutic applications of MSCs. We will discuss the how TGF-β modulate MSC function as well as the paracrine effects of MSC-derived TGF-β on other cell types in the context of tissue regeneration, immune responses and cancer. Finally, taking all these aspects into consideration we discuss how modulation of TGF-β signaling/production in MSCs could be of clinical interest.

Effects of mesenchymal stem cells on solid tumor metastasis in experimental cancer models: a systematic review and meta-analysis

Background

It has been reported mesenchymal stem cells (MSCs) are recruited to and become integral parts of the tumor microenvironment. MSCs might have an active role in solid tumor progression, especially cancer metastasis. However, the contribution of MSCs in the process of cancer metastasis is still controversial. In this review, we performed a meta-analysis on the effects of MSCs administration on cancer metastasis based on published preclinical studies.

Methods

The PRISMA guidelines were used. A total of 42 publications met the inclusion criteria. Outcome data on the incidence and the number of cancer metastasis as well as study characteristics were extracted. Quality of the studies was assessed according to SYRCLE Risk of Bias tool. Random-effects meta-analysis was used to pool estimates.

Results

Of the 42 studies included, 32 reported that MSCs administration promoted outcome events (numbers or incidences of cancer metastasis), and 39 reported data suitable for meta-analysis. The median effect size (RR) was 2.04 for the incidence of cancer metastasis (95% CI 1.57–2.65, I² = 21%), and the median effect size (SMD) was 1.23 for the number of cancer metastasis (95% CI 0.43–2.03, I² = 89%). Heterogeneity was observed, with the greater impact based on study length and different ways of metastasis measurement and MSCs administration.

Conclusion

Our results suggested MSCs administration increased the number and the incidence of cancer metastasis in experimental cancer models. High heterogeneity and poor reported risk of bias limit the quality of these findings. Further preclinical studies with better design and adequate reporting are still needed.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1484-9) contains supplementary material, which is available to authorized users.

In-vitro characterization of canine multipotent stromal cells isolated from synovium, bone marrow, and adipose tissue: a donor-matched comparative study

Background

The dog represents an excellent large animal model for translational cell-based studies. Importantly, the properties of canine multipotent stromal cells (cMSCs) and the ideal tissue source for specific translational studies have yet to be established. The aim of this study was to characterize cMSCs derived from synovium, bone marrow, and adipose tissue using a donor-matched study design and a comprehensive series of in-vitro characterization, differentiation, and immunomodulation assays.

Methods

Canine MSCs were isolated from five dogs with cranial cruciate ligament rupture. All 15 cMSC preparations were evaluated using colony forming unit (CFU) assays, flow cytometry analysis, RT-PCR for pluripotency-associated genes, proliferation assays, trilineage differentiation assays, and immunomodulation assays. Data were reported as mean ± standard deviation and compared using repeated-measures analysis of variance and Tukey post-hoc test. Significance was established at p < 0.05.

Results

All tissue samples produced plastic adherent, spindle-shaped preparations of cMSCs. Cells were negative for CD34, CD45, and STRO-1 and positive for CD9, CD44, and CD90, whereas the degree to which cells were positive for CD105 was variable depending on tissue of origin. Cells were positive for the pluripotency-associated genes NANOG, OCT4, and SOX2. Accounting for donor and tissue sources, there were significant differences in CFU potential, rate of proliferation, trilineage differentiation, and immunomodulatory response. Synovium and marrow cMSCs exhibited superior early osteogenic activity, but when assessing late-stage osteogenesis no significant differences were detected. Interestingly, bone morphogenic protein-2 (BMP-2) supplementation was necessary for early-stage and late-stage osteogenic differentiation, a finding consistent with other canine studies. Additionally, synovium and adipose cMSCs proliferated more rapidly, displayed higher CFU potential, and formed larger aggregates in chondrogenic assays, although proteoglycan and collagen type II staining were subjectively decreased in adipose pellets as compared to synovial and marrow pellets. Lastly, cMSCs derived from all three tissue sources modulated murine macrophage TNF-α and IL-6 levels in a lipopolysaccharide-stimulated coculture assay.

Conclusions

While cMSCs from synovium, marrow, and adipose tissue share a number of similarities, important differences in proliferation and trilineage differentiation exist and should be considered when selecting cMSCs for translational studies. These results and associated methods will prove useful for future translational studies involving the canine model.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0639-6) contains supplementary material, which is available to authorized users.

Long noncoding RNA DANCR regulates miR-1305-Smad 4 axis to promote chondrogenic differentiation of human synovium-derived mesenchymal stem cells

miRNAs have been reported to regulate cellular differentiation by modulating multiple signaling pathways. Long noncoding RNA (lnc RNA) DANCR was previously identified to be critical for the chondrogenesis of human synovium-derived mesenchymal stem cells (SMSC), however, the underlying molecular mechanism requires better understanding. Here, miRNA expression profiling in DANCR overexpressed in SMSCs identified significant down-regulation of miR-1305, which serves as a downstream target of DANCR. Notably, miR-1305 overexpression reversed DANCR-induced cell proliferation and chondrogenic differentiation of SMSCs, which suggested that miR-1305 antagonized the function of DANCR. Mechanistically, highly expressed miR-1305 resulted in the decreased expression of the TGF-β pathway member Smad4, and inhibition of miR-1305 enhanced the expression level of Smad4. Depletion of Smad4 suppressed the promotion of DANCR in cell proliferation and chondrogenesis of SMSCs. Collectively, our results characterized miR-1305-Smad4 axis as a major downstream functional mechanism of lncRNA DANCR in promoting the chondrogenesis in SMSCs.

Combination of Collagen-Based Scaffold and Bioactive Factors Induces Adipose-Derived Mesenchymal Stem Cells Chondrogenic Differentiation In vitro

Recently, multipotent mesenchymal stem cells (MSCs) have attracted much attention in the field of regenerative medicine due to their ability to give rise to different cell types, including chondrocytes. Damaged articular cartilage repair is one of the most challenging issues for regenerative medicine, due to the intrinsic limited capability of cartilage to heal because of its avascular nature. While surgical approaches like chondral autografts and allografts provide symptoms and function improvement only for a short period, MSC based stimulation therapies, like microfracture surgery or autologous matrix-induced chondrogenesis demonstrate to be more effective. The use of adult chondrocytes, which are the main cellular constituent of cartilage, in medical practice, is indeed limited due to their instability in monolayer culture and difficulty to collect donor tissue (articular and nasal cartilage). The most recent cartilage engineering approaches combine cells, biomaterial scaffold and bioactive factors to promote functional tissue replacements. Many recent evidences demonstrate that scaffolds providing specific microenvironmental conditions can promote MSCs differentiation toward a functional phenotype. In the present work, the chondrogenic potential of a new Collagen I based 3D scaffold has been assessed in vitro, in combination with human adipose-derived MSCs which possess a higher chondrogenic potential compared to MSCs isolated from other tissues. Our data indicate that the scaffold was able to promote the early stages of chondrogenic commitment and that supplementation of specific soluble factors was able to induce the complete differentiation of MSCs in chondrocytes as demonstrated by the appearance of cartilage distinctive markers (Sox 9, Aggrecan, Matrilin-1, and Collagen II), as well as by the cartilage-specific Alcian Blue staining and by the acquisition of typical cellular morphology. Such evidences suggest that the investigated scaffold formulation could be suitable for the production of medical devices that can be beneficial in the field of articular cartilage engineering, thus improving the efficacy and durability of the current therapeutic options.

TNFα promotes proliferation of human synovial MSCs while maintaining chondrogenic potential

Synovial mesenchymal stem cells (MSCs) are a candidate cell source for cartilage and meniscus regeneration. If we can proliferate synovial MSCs more effectively, we can expand clinical applications to patients with large cartilage and meniscus lesions. TNFα is a pleiotropic cytokine that can affect the growth and differentiation of cells in the body. The purpose of this study was to examine the effect of TNFα on proliferation, chondrogenesis, and other properties of human synovial MSCs. Passage 1 human synovial MSCs from 2 donors were cultured with 2.5 x 10-12~10-7 g/ml, 10 fold dilution series of TNFα for 14 days, then the cell number and colony number was counted. The effect of the optimum dose of TNFα on proliferation was also examined in synovial MSCs from 6 donors. Chondrogenic potential of synovial MSCs pretreated with TNFα was evaluated in 6 donors. The expressions of 12 surface antigens were also examined in 3 donors.2.5 ng/ml and higher concentration of TNFα significantly increased cell number/dish and cell number/colony in both donors. The effect of 25 ng/ml TNFα was confirmed in all 6 donors. There was no significant difference in the weight, or amount of glycosaminoglycan and DNA of the cartilage pellets between the MSCs untreated and MSCs pretreated with 25 ng/ml TNFα. TNFα decreased expression rate of CD 105 and 140b in all 3 donors. TNFα promoted proliferation of synovial MSCs with increase of cell number/ colony. Pretreatment with TNFα did not affect chondrogenesis of synovial MSCs. However, TNFα affected some properties of synovial MSCs.

Generating Rho-0 Cells Using Mesenchymal Stem Cell Lines

Introduction

The generation of Rho-0 cells requires the use of an immortalization process, or tumor cell selection, followed by culture in the presence of ethidium bromide (EtBr), incurring the drawbacks its use entails. The purpose of this work was to generate Rho-0 cells using human mesenchymal stem cells (hMSCs) with reagents having the ability to remove mitochondrial DNA (mtDNA) more safely than by using EtBr.

Methodology

Two immortalized hMSC lines (3a6 and KP) were used; 143B.TK-Rho-0 cells were used as reference control. For generation of Rho-0 hMSCs, cells were cultured in medium supplemented with each tested reagent. Total DNA was isolated and mtDNA content was measured by real-time polymerase chain reaction (PCR). Phenotypic characterization and gene expression assays were performed to determine whether 3a6 Rho-0 hMSCs maintain the same stem properties as untreated 3a6 hMSCs. To evaluate whether 3a6 Rho-0 hMSCs had a phenotype similar to that of 143B.TK-Rho-0 cells, in terms of reactive oxygen species (ROS) production, apoptotic levels and mitochondrial membrane potential (Δψm) were measured by flow cytometry and mitochondrial respiration was evaluated using a SeaHorse XFp Extracellular Flux Analyzer. The differentiation capacity of 3a6 and 3a6 Rho-0 hMSCs was evaluated using real-time PCR, comparing the relative expression of genes involved in osteogenesis, adipogenesis and chondrogenesis.

Results

The results showed the capacity of the 3a6 cell line to deplete its mtDNA and to survive in culture with uridine. Of all tested drugs, Stavudine (dt4) was the most effective in producing 3a6-Rho cells. The data indicate that hMSC Rho-0 cells continue to express the characteristic MSC cell surface receptor pattern. Phenotypic characterization showed that 3a6 Rho-0 cells resembled 143B.TK-Rho-0 cells, indicating that hMSC Rho-0 cells are Rho-0 cells. While the adipogenic capability was higher in 3a6 Rho-0 cells than in 3a6 cells, the osteogenic and chondrogenic capacities were lower.

Conclusion

Among the drugs and conditions tested, the use of d4t was the best option for producing Rho-0 cells from hMSCs. Rho-0 cells are useful for studying the role of mitochondria in hMSC differentiation.