The highly heterogeneous characteristics of Wharton's jelly mesenchymal stem cells (WJ-MSCs) may be responsible for the poor clinical outcomes and poor reproducibility of treatments based on WJ-MSCs. Exploration of WJ-MSC heterogeneity with multimodal single-cell technologies will aid in establishing accurate MSC subtyping and developing screening protocols for dominant functional subpopulations. Here, the characteristics of WJ-MSCs are systematically analyzed by single cell and spatial transcriptome sequencing. Single-cell transcriptomics analysis identifies four WJ-MSC subpopulations, namely proliferative_MSCs, niche-supporting_MSCs, metabolism-related_MSCs and biofunctional-type_MSCs. Furthermore, the transcriptome, cellular heterogeneity, and cell-state trajectories of these subpopulations are characterized. Intriguingly, the biofunctional-type MSCs (marked by S100A9, CD29, and CD142) selected in this study exhibit promising wound repair properties in vitro and in vivo. Finally, by integrating omics data, it has been found that the S100A9 + CD29 + CD142 + subpopulation is more enriched in the fetal segment of the umbilical cord, suggesting that this subpopulation deriving from the fetal segment may have potential for developing into an ideal therapeutic agent for wound healing. Overall, the presented study comprehensively maps the heterogeneity of WJ-MSCs and provides an essential resource for future development of WJ-MSC-based drugs.

Background Mesenchymal stem cell-based acellular therapies have been widely exploited in managing hypertrophic scars. However, low maintenance dose and transitory therapeutic effects during topical medication remain a thorny issue. Herein, this study aimed to optimize the curative effect of adipose-derived stem cell conditioned medium (ADSC-CM) in the prevention of hypertrophic scarring. Methods In the present study, ADSC-CM was concentrated via the freeze-drying procedure. The efficacy of different dose groups (CM, CM5, CM10) was conducted on the proliferation, apoptosis, and α-smooth muscle actin (α-SMA) expression of human keloid fibroblasts (HKFs) in vitro. Incorporation of adipose-derived stem cell concentrated conditioned medium (ADSCC-CM) into polysaccharide hydrogel was investigated in rabbit ear, in vivo. Haematoxylin-eosin (H&E) and Masson’s trichrome staining were performed for the evaluation of scar hyperplasia. Results We noted that ADSCC-CM could downregulate the α-SMA expression of HKFs in a dose-dependent manner. In the rabbit ear model, the scar hyperplasia in the medium-dose group (CM5) and high-dose group (CM10) was inhibited with reduced scar elevation index (SEI) under 4 months of observation. It is noteworthy that the union of CM5 and polysaccharide hydrogel (CM5+H) yielded the best preventive effect on scar hyperplasia. Briefly, melanin, height, vascularity, and pliability in the CM5+H group were better than those of the control group. Collagen was evenly distributed, and skin appendages could be regenerated. Conclusions Altogether, ADSCC-CM can downregulate the expression of α-SMA due to its anti-fibrosis effect and promote the rearrangement of collagen fibres, which is integral to scar precaution. The in situ cross bonding of ADSCC-CM and polysaccharide hydrogel could remarkably enhance the therapeutic outcomes in inhibiting scar proliferation. Hence, the alliance of ADSCC-CM and hydrogel may become a potential alternative in hypertrophic scar prophylaxis.

Introduction Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and their small extracellular vesicles (hUC-MSC-sEVs) have shown attractive prospects applying in regenerative medicine. This study aimed to compare the therapeutic effects of two agents on osteoarthritis (OA) and investigate underlying mechanism using proteomics. Methods In vitro, the proliferation and migration abilities of chondrocytes treated with hUC-MSCs or hUC-MSC-sEVs were detected by Cell Counting Kit-8 assay and scratch wound assay. In vivo, hUC-MSCs (a single dose of 5 × 10 5 ) or hUC-MSC-sEVs (30 μg/time) were injected into the knee joints of anterior cruciate ligament transection-induced OA model. Hematoxylin and eosin, Safranin O/Fast Green staining were used to observe cartilage degeneration. The levels of cartilage matrix metabolic molecules (Collagen II, MMP13 and ADAMTS5) and macrophage polarization markers (CD14, IL-1β, IL-10 and CD206) were assessed by immunohistochemistry. Finally, proteomics analysis was performed to characterize the proteinaceous contents of two agents. Results In vitro data showed that hUC-MSC-sEVs were taken up by chondrocytes. A total of 15 μg/mL of sEVs show the greatest proliferative and migratory capacities among all groups. In the animal study, hUC-MSCs and hUC-MSC-sEVs alleviated cartilage damage. This effect was mediated via maintaining cartilage homeostasis, as was confirmed by upregulation of the COL II and downregulation of the MMP13 and ADAMTS5. Moreover, the M1 macrophage markers (CD14) were significantly reduced, while the M2 macrophage markers (CD206 and IL-10) were increased in the hUC-MSCs and hUC-MSC-sEVs relative to the untreated group. Mechanistically, we found that many proteins connected to cartilage repair were more abundant in sEVs. Notably, compared to hUC-MSCs, the upregulated proteins in sEVs were mostly involved in the regulation of immune effector process, extracellular matrix organization, PI3K-AKT signaling pathways, and Rap1 signaling pathway. Conclusion Our study indicated that hUC-MSC-sEVs protect cartilage from damage and many cartilage repair-related proteins are probably involved in the restoration process. These data suggest the promising potential of hUC-MSC-sEVs as a therapeutic agent for OA.