ALBERT

Description: Background Scar formation, which may be caused by myofibroblast aggregations, is the greatest challenge during skin wound healing in the clinical setting. Studies have indicated that epidermal stem cells (EPSC) improve wound healing and reduce scar formation. Methods We investigated the therapeutic effects of EPSC-derived exosomes (EPSC-Exos) on skin wound healing in a skin-defect rat model. We also examined the roles of EPSC-Exos-specific microRNAs in inhibiting the differentiation of human dermal fibroblasts (HDF) into myofibroblasts. Results We found that EPSC-Exos increased the wound healing rate and reduced scar formation in rats. Also, EPSC-Exos improved the regeneration levels of skin appendages, nerves and vessels, as well as the natural distribution of collagen. Furthermore, we found these functions may be achieved by inhibiting the activity of transforming growth factor-β1 (TGF-β1) and its downstream genes. The results showed that some specific microRNAs, including miR-16, let-7a, miR-425-5p and miR-142-3p, were enriched in EPSC-Exos. EPSC-Exos-specific microRNAs, especially miR-425-5p and miR-142-3p, played vital roles in inhibiting myofibroblast differentiation via reducing the TGF-β1 expression in dermal fibroblasts. Conclusion We found a novel function of EPSC-Exos-specific microRNAs, suggesting that EPSC-Exos might represent a strategy to prevent scar formation during wound healing in the clinical setting.

Description: Background Pulmonary fibrosis (PF), the end point of interstitial lung diseases, is characterized by myofibroblast over differentiation and excessive extracellular matrix accumulation, leading to progressive organ dysfunction and usually a terminal outcome. Studies have shown that umbilical cord-derived mesenchymal stromal cells (uMSCs) could alleviate PF; however, the underlying mechanism remains to be elucidated. Methods The therapeutic effects of uMSC-derived extracellular vesicles (uMSC-EVs) on PF were evaluated using bleomycin (BLM)-induced mouse models. Then, the role and mechanism of uMSC-EVs in inhibiting myofibroblast differentiation were investigated in vivo and in vitro. Results Treatment with uMSC-EVs alleviated the PF and enhanced the proliferation of alveolar epithelial cells in BLM-induced mice, thus improved the life quality, including the survival rate, body weight, fibrosis degree, and myofibroblast over differentiation of lung tissue. Moreover, these effects of uMSC-EVs on PF are likely achieved by inhibiting the transforming growth factor-β (TGF-β) signaling pathway, evidenced by decreased expression levels of TGF-β2 and TGF-βR2. Using mimics of uMSC-EV-specific miRNAs, we found that miR-21 and miR-23, which are highly enriched in uMSC-EVs, played a critical role in inhibiting TGF-β2 and TGF-βR2, respectively. Conclusion The effects of uMSCs on PF alleviation are likely achieved via EVs, which reveals a new role of uMSC-EV-derived miRNAs, opening a novel strategy for PF treatment in the clinical setting.

Description: Background Scar formation is a common consequence of skin wound healing, and no effective treatment exists. Umbilical cord blood mesenchymal stem cells (UCB-MSCs) can improve wound healing; however, the role of UCB-MSCs remains unclear and whether they can ameliorate scar formation has not been fully elucidated. Methods To determine the function of UCB-MSCs, we examined and compared the therapeutic effects of UCB-MSCs and UCB-MSC-derived exosomes (UCB-MSC-exo) on skin healing in rats. Moreover, UCB-MSC-exo-specific miRNAs were identified and their effects in inhibiting the human dermal fibroblast (HDF) differentiation into myofibroblasts were investigated. Results Both UCB-MSCs and UCB-MSC-exo accelerated wound closure; reduced scar formation; improved the regeneration of skin appendages, nerves, and vessels; and regulated the natural distribution of collagen fibers in wound healing. Additionally, UCB-MSC-exo suppressed the excessive formation of myofibroblasts and collagen I and increased the proliferation and migration of skin cells in vivo and in vitro. Functional analysis showed that UCB-MSC-derived miRNAs were closely related to the transforming growth factor-β (TGF-β) signaling pathway, which could induce myofibroblast differentiation. We identified abundant miRNAs that were highly expressed in UCB-MSC-exo. miR-21-5p and miR-125b-5p were predicted to contribute to TGF-β receptor type II (TGFBR2) and TGF-β receptor type I (TGFBR1) inhibition, respectively. Using miRNA mimics, we found that miR-21-5p and miR-125b-5p were critical for anti-myofibroblast differentiation in the TGF-β1-induced HDF. Conclusion The effect of UCB-MSCs in stimulating regenerative wound healing might be achieved through exosomes, which can be, in part, through miR-21-5p- and miR-125b-5p-mediated TGF-β receptor inhibition, suggesting that UCB-MSC-exo might represent a novel strategy to prevent scar formation during wound healing.