About this Research Topic
Cartilage is specialised tissue comprising a collagenous extracellular matrix that is highly sulphated and hydrated, and which lacks both innervation and vascularisation. Cartilage is an essential skeletal component both as a precursor to developing bones (those formed via endochondral ossificiation) as well as fulfilling unique functions in adult tissues (such as lining the joints). Due to its poor healing capacity, cartilage disorders in both development (which can cause idiopathic short stature, leg length differences) and adulthood (eg. osteoarthritis, rheumatoid arthritis) have poor outcomes and current treatment options are limited.
Stem cell-based therapy has been applied in repairing cartilage injury for decades. For example, the cartilage stem/progenitor cells (CSPCs) that play important roles in maintaining homeostasis have recently been identified. Articular CSPCs primarily reside in the superficial zone of the articular cartilage, which likely supports the maintenance of CSPCs and the generation of underlying articular chondrocytes via signalling from underlying chondrocytes, extracellular matrix and mechanical forces. Similarly, the resting zone of the postnatal epiphyseal growth plate cartilage houses slowly cycling stem cells capable of generating underlying chondrocytes. The components of the secondary ossification center, mTORC1 signalling and hedgehog gradients appear to play important roles in the epiphyseal stem cell niche. There is a significant lack in our understanding of the regulatory factors essential to maintain CSPC properties because isolated CSPCs cultured ex vivo fail to maintain their native traits. Similar to CSPCs, there are other local stem cells that might also influence the cartilage through secretome or migration into cartilage. Knowledge about the mechanisms on the phenotype maintenance and directional differentiation of these stem cells and for the re-establishment of a functional and therapeutic niche would also contribute to the generation of new strategies for translational application to enhance the cartilage regeneration. Overall, the goal of this Research Topic is to consolidate our understanding of stem/progenitor cells across the lifespan of cartilage, from developmental biology to physiology and translational medicine.
We aim to assemble a collection of cutting-edge communications that will broaden our understanding on the developmental and translational biology of stem cells in the context of cartilage. We encourage contributions from developmental and cell biologists, biomaterial specialists, engineer, as well as experts in stem cell niches and tissue modelling. We welcome the submission of Original Research, Methods, Review and Mini-Review articles, Study protocols and Hypotheses that cover, but are not limited to, the following topics:
• Investigate the cartilage development with the special interest on fate determination of progenitor cells.
• Study the niche of cartilage stem/progenitor cells and improve our understanding of how cartilage stem/progenitor cell populations are maintained in physiological and pathological conditions
• Identify molecular mechanisms governing the function of cartilage stem/progenitor cells in vivo and in vitro (organoids, cell sheets, engineered constructs, etc.)
• Investigate the role of stem cells in the pathogenesis of joint diseases.
• Study the aging and senescence of stem cells on cartilage repair.
• Develop new stem cell-based strategy to treat cartilage injury. Special attention will be paid to method that can simulate the regenerative capacity of endogenous stem cells.
Keywords: Cartilage stem/progenitor cells, chondrocyte, cartilage, tissue engineering, articular cartilage, growth plate cartilage, niche, microenvironment
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