BACKGROUND: Although umbilical cord mesenchymal stem cell (UCMSC) infusion has been proposed as a promising strategy for the treatment of acute lung injury (ALI), the parameters of UCMSC transplantation, such as infusion routes and doses, need to be further optimized.
METHODS: In this study, we compared the therapeutic effects of UCMSCs transplanted via intravenous injection and intratracheal instillation on lipopolysaccharide-induced ALI using a rat model. Following transplantation, levels of inflammatory factors in serum; neutrophils, total white blood cells, and lymphocytes in bronchoalveolar lavage fluid (BALF); and lung damage levels were analyzed.
RESULTS: The results indicated that UCMSCs administered via both intravenous and intratracheal routes were effective in alleviating ALI, as determined by analyses of arterial blood gas, lung histopathology, BALF contents, and levels of inflammatory factors. Comparatively, the intratracheal instillation of UCMSCs was found to result in lower levels of lymphocytes and total proteins in BALF, whereas greater reductions in the serum levels of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were detected in rats receiving intravenously injected stem cells.
CONCLUSIONS: Our findings in this study provide convincing evidence to indicate the efficacy of UCMSC therapy in the treatment of ALI mediated via different delivery routes, thereby providing a reliable theoretical basis for further clinical studies. Moreover, these findings imply that the effects obtained using the two assessed delivery routes for UCMSC transplantation are mediated via different mechanisms, which could be attributable to different cellular or molecular targets.

Reduced numbers and dysfunction of thymic epithelial cells (TECs) are important factors of thymic degeneration. Previous studies have found that umbilical cord mesenchymal stem cells (UCMSCs) reverse the structure and function of the senescent thymus in vivo. However, the transcriptomic regulation mechanism is unclear.
TECs were cultured with H2O2 for 72 hours to induce senescence. UCMSCs were cocultured with senescent TECs for 48 hours to detect SA-β-gal, P16 and Ki67. The cocultured TECs were collected for lncRNA, mRNA and miRNA sequencing to establish a competitive endogenous regulatory network (ceRNA). And RT-qPCR, immunofluorescence staining, and western blot were used to identified key genes.
Our results showed that H2O2 induced TEC aging and that UCMSCs reversed these changes. Compared with those in aged TECs, 2260 DE mRNAs, 1033 DE lncRNAs and 67 DE miRNAs were differentially expressed, and these changes were reversed by coculturing the cells with UCMSCs. Differential mRNA enrichment analysis of ceRNA regulation revealed that the PI3K-AKT pathway was a significant signaling pathway. UCMSC coculture upregulated VEGFA, which is the upstream factor of the PI3K-AKT signaling pathway, and the expression of the key proteins PI3K and AKT. Thus, the expression of the cell cycle suppressor P27, which is downstream of the PI3K-AKT signaling pathway, was downregulated, while the expression of the cell cycle regulators CDK2 and CCNE was upregulated.
UCMSC coculture upregulated the expression of VEGFA, activated the PI3K-AKT signaling pathway, increased the expression of CDK2 and CCNE, decreased the expression of P27, and promoted the proliferation of TECs.

Chronic ocular graft-versus-host disease (oGVHD) is a common complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and can lead to vision loss if not diagnosed and treated promptly. Currently, no approved drugs exist for oGVHD treatment. However, umbilical cord-derived mesenchymal stem cells (UCMSCs) have known immunoregulatory properties and have been employed in clinical trials for immune-mediated diseases. To address oGVHD, the application of UCMSCs to the ocular surface is a logical approach. Intravenous administration of UCMSCs poses risks, necessitating topical and local delivery. Retaining UCMSCs on the ocular surface remains a challenge. To overcome this, we invented mesenchymal stem cell-coating high oxygen-permeable hydrogel lenses combining UCMSCs and machinery to enable the long-term retention of UCMSCs on the ocular surface. Animal model experiments demonstrated that these lenses effectively retained UCMSCs, providing therapeutic benefits by decreasing corneal inflammation and damage, and inhibiting immune rejection and response, all crucial aspects in oGVHD treatment.

Experiments confirmed that circular RNAs contributed to the pathogenesis of diabetic foot ulcers (DFUs). CircHIPK3 was upregulated in type 2 diabetes mellitus (T2DM), but its role in DFU remained unknown. Our study aimed to investigate the regulatory functions of exosomal circHIPK3 and its potential mechanisms in DFU.
Exosomal size and distribution, marker proteins, and circHIPK3 levels were evaluated by transmission electron microscope, ExoView R200, western blot, and qRT-PCR. Flow cytometry, MTT, Wound healing assays, and tube formation assays were used to assess the roles of exosomal circHIPK3 in high glucose (HG)-treated human umbilical vein endothelial cells (HUVECs). The relationships between Nrf2/VEGFA/circHIPK3 and miR-20b-5p, and between Nrf2 and VEGFA were determined by luciferase reporter assay and RNA immunoprecipitation. We used cell and mice models to investigate the mechanisms of exosomal circHIPK3 under diabetic conditions.
CircHIPK3 was significantly upregulated in exo-circHIPK3 rather than exo-vector. Exo-circHIPK3 remarkably inhibited cell apoptosis but promoted cell proliferation, migration, and tube formation in HG-treated HUVECs. Luciferase reporter and RIP assays showed that miR-20b-5p targeted and inhibited Nrf2 and VEGFA, and circHIPK3 acted as a ceRNA of miR-20b-5p to inhibit the binding to its downstream genes Nrf2 and VEGFA. Mechanistically, circHIPK3 promoted cell proliferation, migration, and angiogenesis via downregulating miR-20b-5p to upregulate Nrf2 and VEGFA. However, the overexpressed miR-20b-5p could abolish the promoting effects of circHIPK3 overexpression on cell proliferation, migration, and tube formation under HG conditions.
UCMSCs-derived exosomal circHIPK3 protected HG-treated HUVECs via miR-20b-5p/Nrf2/VEGFA axis. The exosomal circHIPK3 might be a therapeutic candidate to treat DFU.

BACKGROUND: Endometrial injury is considered the major cause of female infertility. Traditional therapies such as estrogen substitution therapy are not satisfactory due to individual variation in response to treatment, thereby warranting the use of alternative strategies such as stem cell therapy. Transplantation of stem cells, such as umbilical cord mesenchymal stem cells (UCMSCs), has been shown to improve endometrial healing. However, due to the effect of the intrauterine environment, the therapeutic effect of UCMSCs is limited, and its efficacy is unstable. HOXA10, encoded by the HOXA10 gene, plays an important role in endometrium morphology maintenance, proliferation, differentiation, and embryo implantation. Moreover, UCMSCs do not show HOXA10 expression.
OBJECTIVE: Our study aimed to evaluate the therapeutic effects of HOXA10-transfected UCMSCs on endometrial injury repair in vivo.
METHODS: First, we established T10-UCMSCs (UCMSCs transfected with HOXA10) for transplantation. To establish the endometrial injury model, we injected 95% ethanol into the uterine cavity and transplanted T10-UCMSCs into the uterine cavity from the cornua uteri. Fourteen days later, uteri were collected for histological and biochemical analysis of endometrial growth and receptivity.
RESULTS: Our results showed the endometrial receptivity was better in T10-UCMSCs group than in UCMSCs group, suggesting that HOXA10 could enhance the repairing ability of UCMSCs in the endometrium injury repair. More importantly, the fertility test showed that more embryos were implanted in the T10- UCMSCs group.
CONCLUSIONS: Our results suggest that UCMSCs with HOXA10 expression could improve the therapeutic effects on endometrial injury repairing.

Uterine scar was one of the long-term complications cesarean section. In this study, an thermo-responsive injectable hydrogel loaded with human umbilical cord mesenchymal stem cells (UCMSCs) and asiaticoside microspheres (AMs) was used for uterine scar repair, which was prepared by optimizing the mixed ratio of aldehyde-functionalized Pluronic F127 (F127-CHO) and adipic dihydrazide-modified hyaluronic acid (AHA). The asiaticoside was loaded in Poly (DL-lactide-co-gycolide) (PLGA) by emulsion- diffusion-evaporation method. The hydrogel had appropriate pore size, good mechanical property, and slow release ability of asiaticoside. In vitro cell experiments demonstrated that F127-CHO/AHA/AMs could effectively promote stem cell adhesion and proliferation, promote angiogenesis, and provide a suitable microenvironment for cell survival. The F127-CHO/AHA/AMs/UCMSCs hydrogel was further used to repair uterine scar in female SD rats. The results showed that the prepared hydrogel could promote the proliferation of rat endometrial cells, promote the regeneration of glands, reduce the degree of endometrial fibrosis and restore the morphology of uterine cavity. The hydrogel could upregulate expression of Ki67 and IGF-1, downregulate TGF-β1 expression and promote M1-M2 transition of macrophages. This study confirmed that the prepared hydrogel could be used as an effective transplantation strategy, which could be expected to achieve clinical transformation of uterine scar repair.

The endemic and pandemic caused by respiratory virus infection are a major cause of mortality and morbidity globally. Thus, broadly effective antiviral drugs are needed to treat respiratory viral diseases. Small extracellular vesicles derived from human umbilical cord mesenchymal stem cells (U-exo) have recently gained attention as a cell-free therapeutic strategy due to their potential for safety and efficacy. Anti-viral activities of U-exo to countermeasure respiratory virus-associated diseases are currently unknown. Here, we tested the antiviral activities of U-exo following influenza A/B virus (IFV) and human seasonal coronavirus (HCoV) infections in vitro. Cells were subject to IFV or HCoV infection followed by U-exo treatment. U-exo treatment significantly reduced IFV or HCoV replication and combined treatment with recombinant human interferon-alpha protein (IFN-α) exerted synergistically enhanced antiviral effects against IFV or HCoV. Interestingly, microRNA (miR)-125b, which is one of the most abundantly expressed small RNAs in U-exo, was found to suppress IFV replication possibly via the induction of IFN-stimulated genes (ISGs). Furthermore, U-exo markedly enhanced RNA virus-triggered IFN signaling and ISGs production. Similarly, human nasal epithelial cells cultured at the air-liquid interface (ALI) studies broadly effective anti-viral and anti-inflammatory activities of U-exo against IFV and HCoV, suggesting the potential role of U-exo as a promising intervention for respiratory virus-associated diseases.

Few therapies can reverse the proangiogenic activity of senescent mesenchymal stromal/stem cells (MSCs). In this study, we investigated the effects of rapamycin on the proangiogenic ability of senescent human umbilical cord MSCs (UCMSCs). An in vitro replicative senescent cell model was established in cultured UCMSCs. We found that late passage (P25 or later) UCMSCs (LP-UCMSCs) exhibited impaired proangiogenic abilities. Treatment of P25 UCMSCs with rapamycin (900 nM) reversed the senescent phenotype and notably enhanced the proangiogenic activity of senescent UCMSCs. In a nude mouse model of hindlimb ischemia, intramuscular injection of rapamycin-treated P25 UCMSCs into the ischemic limb significantly promoted neovascularization and ischemic limb salvage. We further analyzed the changes in the expression of angiogenesis-associated genes in rapamycin-primed MSCs and found higher expression of several genes related to angiogenesis, such as VEGFR2 and CTGF/CCN2, in primed cells than in unprimed MSCs. Taken together, our data demonstrate that rapamycin is a potential drug to restore the proangiogenic activity of senescent MSCs, which is of importance in treating ischemic diseases and tissue engineering.

A hypoxic microenvironment is a common feature of skin wounds. Our previous study demonstrated that three-dimensional coculture of umbilical cord-derived mesenchymal stem cells (ucMSCs) and endothelial cells facilitates cell communication and host integration in skin tissue engineering. Here, we aimed to identify the mechanism by which ucMSCs affect endothelial cells under hypoxic conditions after skin injury. We demonstrate that hypoxia enhances the exosome-mediated paracrine function of ucMSCs, which increases endothelial cell proliferation and migration. In a mouse full-thickness skin injury model, ucMSC-derived exosomes can be taken up by endothelial cells and accelerate wound healing. Hypoxic exosomes lead to a better outcome than normoxic exosomes by promoting proliferation and inhibiting apoptosis. Mechanistically, microRNA-125b (miR-125b) transcription is induced by hypoxia in ucMSCs. After being packaged into hypoxic exosomes and transported to endothelial cells, miR-125b targets and suppresses the expression of tumor protein p53 inducible nuclear protein 1 (TP53INP1) and alleviates hypoxia-induced cell apoptosis. Inhibition of miR-125b-TP53INP1 interaction attenuates the protective effect of hypoxic exosomes. Moreover, artificial agomiR-125b can accelerate wound healing in vivo. Our findings reveal communication between ucMSCs and endothelial cells via exosomal miR-125b/TP53INP1 signaling in the hypoxic microenvironment and present hypoxic exosomes as a promising therapeutic strategy to enhance cutaneous repair.

Radiation enteritis is the most common and serious complication of abdominal or pelvic radiation therapy. Mesenchymal stem cells (MSCs), as well as cell protection agents, inhibit apoptosis and promote the proliferation of injured tissues. 3 human umbilical cords MSCs (UCMSCs) were injected into the tail vein or peritoneal cavity of a rat model of radiation enteritis. The temporary protective effect was assessed by identification of donor cells, detection of cellular immune parameters and inflammatory cytokine levels, quantitation of jejunum mucosal preservation and examination of the rat remaining life. Only the rats in the intraperitoneal injection group exhibited a few positive donor cells 7 days after transplantation. CD4 +/CD8 + T cells, a cellular immune parameter, decreased in the abdominal exudate of intraperitoneal injection group, compared with the model-only control and tail vein groups (both P < .05). Both serum and abdominal exudate TNF-α and IL-6 levels in the intraperitoneally injected rats rapidly decreased and were significantly different from those in the model-only control and tail vein injection groups (all P < .05). Mucosal surface area and survival time increased in the intraperitoneal injection group compared with the vehicle and tail vein injection groups (all P = .000). Therefore, the administration of UCMSCs with intraperitoneal injection approach postponed death in a rat model of radiation enteritis, which was associated with reduced serum levels of proinflammatory cytokines (TNF-α, IL-6). However, UCMSCs injected via the tail vein triggered an intense cellular immune response in the serum that adversely affects their survival. This treatment failed to suppress circulating serum and abdominal exudate levels of TNF-α and IL-6 and could not provide a therapeutic benefit for prolonging life against acute radiation enteritis.