Within bone, mesenchymal stromal cells (MSCs) exist within the bone marrow stroma (BM-MSC) and the endosteal niche, as cells lining compact bone (CB-MSCs). This study isolated and characterised heterogeneous MSC populations from each niche and subsequently investigated the effects of extensive cell expansion, analysing population doublings (PDs)/cellular senescence, colony-forming efficiencies (CFEs), MSC cell marker expression, and osteogenic/adipogenic differentiation. CB-MSCs and BM-MSCs demonstrated similar morphologies and PDs, reaching 100 PDs. Both populations exhibited consistent telomere lengths (12–17 kb), minimal senescence, and positive telomerase expression. CB-MSCs (PD15) had significantly lower CFEs than PD50. CB-MSCs and BM-MSCs both expressed MSC (CD73/CD90/CD105); embryonic (Nanog) and osteogenic markers (Runx2, osteocalcin) but no hematopoietic markers (CD45). CB-MSCs (PD15) strongly expressed Oct4 and p16INK4A. At early PDs, CB-MSCs possessed a strong osteogenic potency and low potency for adipogenesis, whilst BM-MSCs possessed greater overall bipotentiality for osteogenesis and adipogenesis. At PD50, CB-MSCs demonstrated reduced potency for both osteogenesis and adipogenesis, compared to BM-MSCs at equivalent PDs. This study demonstrates similarities in proliferative and mesenchymal cell characteristics between CB-MSCs and BM-MSCs, but contrasting multipotentiality. Such findings support further comparisons of human CB-MSCs and BM-MSCs, facilitating selection of optimal MSC populations for regenerative medicine purposes.

BackgroundMesenchymal stromal cells in the endosteal niche lining compact bone (CB-MSCs) represent a heterogeneous population, all of which contribute to bone repair and remodelling. Hyperglycaemia associated with type 2 diabetes mellitus (T2DM) can delay and impair the bone healing process. Therefore, this study investigated the influences of high (25 mM) glucose conditions on CB-MSC populations isolated from male Wistar rats, versus normal (5.5 mM) glucose conditions; in terms of proliferation (population doublings, PDs), senescence characteristics, stem cell marker expression, colony forming efficiencies (CFEs); and osteogenic/adipogenic differentiation, following extended culture in vitro.ResultsCB-MSCs under both normoglycaemic and hyperglycaemic conditions demonstrated similar morphologies and rapid exponential growth to >300PDs, although high glucose conditions promoted more rapid and persistent proliferation beyond ~50PDs, with few indications of senescence. Limited senescence was confirmed by minimal SA-β-galactosidase staining, low senescence marker (p53, p21waf1, p16INK4a) expression and positive telomere maintenance marker (rTERT, TR) expression. However, telomere lengths varied throughout culture expansion, with hyperglycaemia significantly reducing telomere lengths at PD50 and PD200. Furthermore, CB-MSCs expanded in normal and high glucose conditions remained non-transformed, exhibiting similar MSC (CD73/CD90/CD105), multipotency (CD146) and embryonic (Slug, Snail) markers throughout extended culture, but negligible hematopoietic (CD34/CD45) or pluripotency (Nanog, Oct4) markers. Hyperglycaemia significantly increased CFEs at PD50 and PD100, which decreased at PD200. CB-MSC osteogenic differentiation was also inhibited by hyperglycaemia at PD15, PD100 and PD200, but not at PD50. Hyperglycaemia inhibited CB-MSC adipogenic differentiation to a lesser extent at PD15 and PD50, with reduced adipogenesis overall at PD100 and PD200.ConclusionThis study demonstrates the limited negative impact of hyperglycaemia on the proliferative and stem cell characteristics of heterogeneous CB-MSC populations, although minor sub-population(s) appear more susceptible to these conditions leading to impaired osteogenic/adipogenic differentiation capabilities. Such findings potentially highlight the impact of hyperglycaemia on CB-MSC bone repair capabilities in situ.

Stem cells play an essential role in maintaining homeostasis, as well as participating in new tissue regeneration. Over the past 20 years, a great deal of effort has been made to investigate the behaviour of stem cells to enable their potential use in regenerative medicine. However, a variety of biological characteristics are known to exist among the different types of stem cells due to variations in the methodological approach, formulation of cell culture medium, isolation protocol and cellular niches, as well as species variation. In recent years, cell-based therapy has emerged as one of the advanced techniques applied in both medical and clinical settings. Cell therapies aim to treat and repair the injury sites and replace the loss of tissues by stimulating the repair and regeneration process. In order to enable the use of stem cells in regenerative therapies, further characterisation of cell behaviour, in terms of their proliferation and differentiation capacity, mainly during the quiescent and inductive state is regarded as highly necessary. The central focus of regenerative medicine revolves around the use of human cells, including adult stem cells and induced pluripotent stem cells for cell-based therapy. The purpose of this review was to examine the existing body of literature on stem cell research conducted on cellular angiogenesis and migration, to investigate the validity of different strategies and variations of the cell type used. The information gathered within this review may then be shared with fellow researchers to assist in future research work, engaging in stem cell homing for cell-based therapy to enhance wound healing and tissue regeneration process.

Background: The migration and differentiation of stem cells take place during the reparative phase of the healing cascade. Chemokine ligands and receptors are the key players in the homing process dur-ing the early stage of capillary morphogenesis. Stem cells from exfo-liated deciduous teeth are known to possess a huge potential benefit for tissue regeneration. However, the gene expression of SHED en-gaging in angiogenesis and migratory activity during tissue healing is not fully understood. This study aims to assess the gene expression of SHED following in-vitro angiogenesis and migratory induction protocol. Methods: Scratch test assay was conducted following an angiogenic induction of SHED by supplementation of EGM-2 and VEGF. For the detection of migratory cell markers, angiogenic markers, and stem cell markers, RNA samples were extracted on day 1, 3, 7, 10, and 14 after the angiogenic induction in a transwell chamber, fol-lowed by RT-PCR analysis. Results: The findings suggested that SHED forming endothelial cells at higher capacity under an imma-ture state with higher seeding density. SHED undergoing angiogen-esis and migratory activity showed elevated IL-8, CCR1, CXCR4 and CCL28 expression. CCR1 expression significantly increased in the A+M+ group (p<0.05). Conclusion: The gene expression of these chemokines, particularly CCR1, which closely represent cellular migration, suggests the po-tential use of SHED for cell-based therapy to enhance tissue repair.