Differential Extracellular Matrix Production by Mesenchymal Stromal Cells From Foetal Skin, Adult Skin and Burn Eschar.

After full-thickness injuries, foetal skin regenerates, while adult skin heals with scarring. Upon injury, mesenchymal stromal cells (MSCs) produce extracellular matrix (ECM) that shapes the wound microenvironment by providing structure, regulating the availability of soluble factors and directing cell behaviour. Therefore, the ECM secreted by MSCs likely guides the healing outcome towards either scarless or scar prone healing. We analysed the ECM produced by primary human MSCs from foetal skin (hfS-MSCs; regenerative/healthy), adult dermis (hD-MSCs; scarring/healthy) and burn eschar tissue (hBE-MSCs; scarring/wounded). We first optimised ECM production across MSC populations, then quantified total ECM deposition, collagen and total protein content and analysed ECM-related genes. Finally, we assessed collagen maturity in foetal versus adult skin. Standard medium containing 10 μg/mL of magnesium ascorbyl phosphate stimulated ECM deposition in all MSC populations, while minimising ECM area reduction and contraction. Total protein, collagen gene and protein expressions were higher in hfS-MSC-derived ECM, while ECMs derived from hBE-MSCs and hD-MSCs showed an increased proportion of non-collagenous proteins. Collagen I:V gene ratio was decreased in hfS-MSCs, while collagen I:III gene ratio was increased in hBE-MSCs compared to hD-MSCs. Both hfS-MSCs and hBE-MSCs showed increased ECM deposition and collagen insolubility. Moreover, hBE-MSCs showed higher ECM contraction, as well as PLOD2 and fibronectin gene expression. Foetal skin exhibited higher immature collagen, whereas adult skin exhibited higher mature collagen. We revealed intrinsic differences in ECM amount, composition and ECM-related gene expression between MSC populations and their tissues of origin, suggesting potential ECM-related biomarkers underlying regeneration or repair.