The crosstalk between mesenchymal stem cells and damaged cartilage in osteoarthritis

Human cartilage contains multipotent stem cells, namely mesenchymal stem cells (MSCs) which are progenitors of connective tissue that play homeostatic and reparative roles. Although the major constituent cells in the cartilage are chondrocytes, they possess a limited regenerative ability, and as a result, spontaneous cartilage repair by chondrocytes leads to the synthesis of fibrocartilage. Similarly, MSCs derived from articular cartilage of osteoarthritis patients have demonstrated inadequacy in cartilage repair. The role of MSCs in the pathophysiology of osteoarthritis (OA) is not entirely understood, whether the inflammatory milieu associated with OA joints affects the reparative properties of MSCs or the inherent defects of OA cartilage-derived MSCs impair the proper execution of the required immunosuppressive and reparative functions. Therefore, the current review explores the biological characteristics and features of MSCs derived from physiological state and OA condition with the aim of identifying how OA affects MSC functions as well as the role of MSCs in the pathophysiology of OA

Human mesenchymal stem cells-mediated transcriptomic regulation of leukemic cells in delivering anti-tumorigenic effects

Treatment of leukemia has become much difficult because of resistance to the existing anticancer therapies. This has thus expedited the search for alternativ therapies, and one of these is the exploitation of mesenchymal stem cells (MSCs) towards control of tumor cells. The present study investigated the effect of human umbilical cord-derived MSCs (UC-MSCs) on the proliferation of leukemic cells and gauged the transcriptomic modulation and the signaling pathways potentially affected by UC-MSCs. The inhibition of growth of leukemic tumor cell lines was assessed by proliferation assays, apoptosis and cell cycle analysis. BV173 and HL-60 cells were further analyzed using microarray gene expression profiling. The microarray results were validated by RT-qPCR and western blot assay for the corresponding expression of genes and proteins. The UC-MSCs attenuated leukemic cell viability and proliferation in a dose-dependent manner without inducing apoptosis. Cell cycle analysis revealed that the growth of tumor cells was arrested at the G0/G1 phase. The microarray results identified that HL-60 and BV173 share 35 differentially expressed genes (DEGs) (same expression direction) in the presence of UC-MSCs. In silico analysis of these selected DEGs indicated a significant influence in the cell cycle and cell cycle-related biological processes and signaling pathways. Among these, the expression of DBF4, MDM2, CCNE2, CDK6, CDKN1A, and CDKN2A was implicated in six different signaling pathways that play a pivotal role in the anti-tumorigenic activity exerted by UC-MSCs. The UC-MSCs perturbate the cell cycle process of leukemic cells via dysregulation of tumor suppressor and oncogene expression

Immunomodulatory and gene expression characterisation of human mesenchymal stem cells derived from non-osteoarthritic and osteoarthritic cartilage

Osteoarthritis (OA) is a degenerative disease characterised by progressive loss of articular cartilage which affects millions of people globally. Although the leading causes of OA are still elusive, the increasing body of evidence indicates that the predisposing factors such as lifestyle, age, injuries and genetics associated with the onset of OA. The regeneration of the degraded cartilage tissue in OA is mediated by the tissue-resident stem cells. However, in advanced OA, the regenerative and tissue repair capability of tissue-resident stem cells is compromised as a result of diseases condition and leads to an unusual stem cell nature. Mesenchymal stem cells (MSCs) have been implicated in the pathogenesis of OA and, in turn, the progression of the disease could be therapeutically modulated by MSCs. However, it remains unclear whether the defective tissue-resident MSCs contributes to the pathogenesis of OA by a depleted stem cell pool or loss of the chondrogenic differentiation potential which impedes on the proper execution of stem cell functions. Therefore, this study aimed to explore the biological properties of human non-OA and OA cartilage-derived MSCs (C-MSCs) as well as to determine whether the defects in human OA C-MSCs are results of an inherent genetic make-up or acquired from the exposure of pathological OA inflammatory environment. A small fraction of non-weight bearing human articular cartilage from non-OA subjects and OA patients were harvested during the arthroscopy session. Patients (n=11) were selected based on the grade 4 osteoarthritis according to the Kleegren and Lawrence score system, and five cartilage samples were obtained from nonosteoarthritic donors undergoing knee surgery or arthroscopy due to the sports injury. The optimised enzymatic digestion and serial plating methods were used to generate cartilage-derived MSCs. The differences in biological features of OA compared to non-OA C-MSCs as well as that of non-OA C-MSCs cultured in OA synovial fluid were investigated through a series of proliferation, cell cycle and apoptosis assays. The secretome profile and the global gene expression were performed through cytokine antibody arrays and microarray, respectively. Mesenchymal stem cells were successfully generated from the human OA cartilage tissues along with non-OA cartilage. As compared to the human non-OA C-MSCs, the counterpart from OA exhibited compromised cell qualities in term of ill-defined morphology specifically at late passages, lower colony forming ability, reduced chondrogenesis when induced, a higher tendency towards osteogenic and adipogenic differentiation. However, the immunophenotypic profile between these two groups remained relatively same. Additionally, human OA C-MSCs also demonstrated slower growth kinetics, prolonged doubling time, increased susceptibility to senescence especially at late passages, reduced proliferation and poor immunosuppressive ability against T cells. It was also observed that during the in vitro culture expansion, the human OA C-MSCs underwent escalated level of cellular senescence in late passage (80%), apoptosis (i.e. 18.33±0.1% early apoptosis, 6.46±0.2% late apoptosis at passage 3 and 20.09±0.1% early apoptosis, 8.42±0.2% late apoptosis at passage 6), exhibited G0/G1 cell cycle arrest (i.e. 78.68±3.17% of cells in G0/G1 phase, at passage 3 while passage 6 had 93.23±2.64% of cells in G0/G1 phase) with a secretome profile that reveals the downregulation of anti-inflammatory cytokines such as IL-1, IL-6, and IL-10, as well as aberrations in gene expression. Analysis of OA synovial fluid indicated with presence of proinflammatory cytokines that associated with OA pathophysiology while pre-treated non-OA C-MSCs with OA synovial fluid exhibited increased apoptosis (i.e. 28.42±0.66% early apoptosis and 12.11±0.47% late apoptosis) and inhibition of proliferation via cell cycle arrest (i.e.78.62±4.38% of cells in G0/G1 phase and 12.42±1.53% of cells in S phase). These findings suggest that the catabolic and inflammatory agents in the synovial fluid could be implicated in cartilage tissue degradation, and may also be involved in the alteration of the inherent genetic makeup of cartilage tissue-resident MSCs which is evident from the aberrant gene expression. The microarray-based gene expression analysis of OA C-MSCs indicated dysregulation of essential genes of cell proliferation and survival, whereas the gene expression of non-OA MSCs treated with OA synovial fluid revealed dysregulation of cartilage metabolism. The KEGG pathway analysis based on the dysregulated gene expression showed the involvement of several key signalling pathways especially Wnt signalling, cell adhesion molecule pathway, Ras signalling pathway, cytokine-cytokine receptor interaction pathway. In conclusion, the biological features of OA C-MSCs are negatively affected by OA disease. It could be possible that the inflammatory condition of OA synovial fluid impedes the functional properties of cartilage tissue-resident MSCs. Thus, treatment strategies for OA should be strategized by allotting an appropriate concern to the inflammatory condition that limits the function of tissue stem cells and therapeutically transplanted stem cells

Mesenchymal stem cell-mediated T cell immunosuppression

Besides being a pool forstromal cells and connective tissues, the mesenchymal stem cells (MSCs) as well exert a potent immunosuppression against almost all types of immune cells, particularly T cells. Many in vitro and in vivo studies revealed that the reported regenerative property of MSCs is partially due to the immunosuppressive activity of MSCs where it creates an optimal microenvironment for the execution of reparative and restorative processes. To date, MSCs caninteract with nearly all cells of the immune system, in a convoluted mechanism with theabilityof inhibiting the activation, proliferation, and function of T cells. These characteristicsshowcaseMSCs’ candidature as anaturalimmunosuppressive agent in regenerative medicine, therapies for immune disorders and tissue engineering. In this review, the intricate mechanisms of MSC-mediated immunosuppression on Tcellswere briefly evaluated. The physical, paracrine and molecular interactions that being toolsfor delivering the immunosuppressionwere also highlighted

Moringa oleifera leaf ethanol extract immunomodulatory activity discriminates between chronic myeloid leukaemia cell line and normal lymphocytes

Introduction: Moringa oleifera, a member of the family Moringaceae, is a small-medium sized tree, widely cultivated in Southeast Asia, Polynesia, and the West Indies, where the leaves, fruits and flowers form part of their routine diet. The plant has been reported to possess numerous pharmacological properties; however, its immunomodulatory po- tentials were least explored, especially on lymphocytes. Therefore, this study aimed to investigate the in vitro immu- nomodulatory effect of Moringa oleifera leaves’ ethanol extract (MOETE) on transformed and normal lymphocytes, the leukaemic cell line BV173 and healthy peripheral blood mononuclear cells (PBMCs), respectively. Methods: The freshly collected and dried Moringa oleifera leaves were extracted using 70% ethanol, and the cytotoxicity activity on transformed and normal lymphocytes was determined using an MTT assay. The immunomodulatory effect was further evaluated through cell proliferation assays, cell cycle analysis and apoptosis assays. Results: The ethanolic extract of Moringa oleifera leaves showed concentration-dependent cytotoxic effects on the BV173 cell line with an IC50 of 125±6 µg/mL while exerting a stimulatory effect on PBMCs (EC50 = 28±3 µg/mL). The extract also exerted antiproliferative effects, cell cycle arrest and apoptosis in the BV173 tumour cell but enhanced the viability and proliferation of PBMCs by committing the cells into the cell cycle and reducing apoptosis despite stimulation by phytohemagglutinin (PHA). Conclusion: The MOETE has immunostimulatory properties on normal lymphocytes and anti-tumour activity on the leukaemic cell lines