Mesenchymal stem cells (MSCs) have been considered as an attractive tool for the therapy of diseases. Exosomes excreted from MSCs can reduce myocardial ischemia/reperfusion damage and protect against acute tubular injury. However, whether MSC-derived exosomes can relieve liver fibrosis and its mechanism remain unknown. Previous work showed that human umbilical cord-MSCs (hucMSCs) transplanted into acutely injured and fibrotic livers could restore liver function and improve liver fibrosis. In this study, it was found that transplantation of exosomes derived from hucMSC (hucMSC-Ex) reduced the surface fibrous capsules and got their textures soft, alleviated hepatic inflammation and collagen deposition in carbon tetrachloride (CCl ₄ )-induced fibrotic liver. hucMSC-Ex also significantly recovered serum aspartate aminotransferase (AST) activity, decreased collagen type I and III, transforming growth factor (TGF)-β1 and phosphorylation Smad2 expression in vivo. In further experiments, we found that epithelial-to-mesenchymal transition (EMT)-associated markers E-cadherin-positive cells increased and N-cadherin- and vimentin-positive cells decreased after hucMSC-Ex transplantation. Furthermore, the human liver cell line HL7702 underwent typical EMT after induction with recombinant human TGF-β1, and then hucMSC-Ex treatment reversed spindle-shaped and EMT-associated markers expression in vitro. Taken together, these results suggest that hucMSC-Ex could ameliorate CCl ₄ -induced liver fibrosis by inhibiting EMT and protecting hepatocytes. This provides a novel approach for the treatment of fibrotic liver disease.

Mesenchymal stem cell-derived exosomes (MSC-Ex) play important roles in tissue injury repair, however, the roles of MSC-Ex in skin damage repair and its mechanisms are largely unknown. Herein, we examined the benefit of human umbilical cord MSC-derived exosome (hucMSC-Ex) in cutaneous wound healing using a rat skin burn model. We found that hucMSC-Ex-treated wounds exhibited significantly accelerated re-epithelialization, with increased expression of CK19, PCNA, collagen I (compared to collagen III) in vivo. HucMSC-Ex promoted proliferation and inhibited apoptosis of skin cells after heat-stress in vitro. We also discovered that Wnt4 was contained in hucMSC-Ex, and hucMSC-Ex-derived Wnt4 promoted β-catenin nuclear translocation and activity to enhance proliferation and migration of skin cells, which could be reversed by β-catenin inhibitor ICG001. In vivo studies confirmed that the activation of Wnt/β-catenin by hucMSC-Ex played a key role in wound re-epithelialization and cell proliferation. Furthermore, knockdown of Wnt4 in hucMSC-Ex abrogated β-catenin activation and skin cell proliferation and migration in vitro. The in vivo therapeutic effects were also inhibited when the expression of Wnt4 in hucMSC-Ex was interfered. In addition, the activation of AKT pathway by hucMSC-Ex was associated with the reduction of heat stress-induced apoptosis in rat skin burn model. Collectively, our findings indicate that exosome-delivered Wnt4 provides new aspects for the therapeutic strategy of MSCs in cutaneous wound healing. Stem Cells 2015;33:2158–2168

Exosomes have emerged as a novel mode of intercellular communication. Exosomes can shuttle bioactive molecules including proteins, DNA, mRNA, as well as non-coding RNAs from one cell to another, leading to the exchange of genetic information and reprogramming of the recipient cells. Increasing evidence suggests that tumor cells release excessive amount of exosomes, which may influence tumor initiation, growth, progression, metastasis, and drug resistance. In addition, exosomes transfer message from tumor cells to immune cells and stromal cells, contributing to the escape from immune surveillance and the formation of tumor niche. In this review, we highlight the recent advances in the biology of exosomes as cancer communicasomes. We review the multifaceted roles of exosomes, the small secreted particles, in communicating with other cells within tumor microenvironment. Given that exosomes are cell type specific, stable, and accessible from body fluids, exosomes may provide promising biomarkers for cancer diagnosis and represent new targets for cancer therapy.

Cancer-associated fibroblasts (CAFs), as a central component of the tumor microenvironment in primary and metastatic tumors, profoundly influence the behavior of cancer cells and are involved in cancer progression through extensive interactions with cancer cells and other stromal cells. Furthermore, the innate versatility and plasticity of CAFs allow their education by cancer cells, resulting in dynamic alterations in stromal fibroblast populations in a context-dependent manner, which highlights the importance of precise assessment of CAF phenotypical and functional heterogeneity. In this review, we summarize the proposed origins and heterogeneity of CAFs as well as the molecular mechanisms regulating the diversity of CAF subpopulations. We also discuss current strategies to selectively target tumor-promoting CAFs, providing insights and perspectives for future research and clinical studies involving stromal targeting.

Introduction: Administration of bone marrow mesenchymal stem cells (MSCs) or secreted microvesicles improves recovery from acute kidney injury (AKI). However, the potential roles and mechanisms are not well understood. In the current study, we focused on the protective effect of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-ex) on cisplatin-induced nephrotoxicity in vivo and in vitro. Methods: We constructed cisplatin-induced AKI rat models. At 24 h after treatment with cisplatin, hucMSC-ex were injected into the kidneys via the renal capsule; human lung fibroblast (HFL-1)-secreted exosomes (HFL-1-ex) were used as controls. All animals were killed at day 5 after administration of cisplatin. Renal function, histological changes, tubular apoptosis and proliferation, and degree of oxidative stress were evaluated. In vitro, rat renal tubular epithelial (NRK-52E) cells were treated with or without cisplatin and after 6 h treated with or without exosomes. Cells continued to be cultured for 24 h, and were then harvested for western blotting, apoptosis and detection of degree of oxidative stress. Results: After administration of cisplatin, there was an increase in blood urea nitrogen (BUN) and creatinine (Cr) levels, apoptosis, necrosis of proximal kidney tubules and formation of abundant tubular protein casts and oxidative stress in rats. Cisplatin-induced AKI rats treated with hucMSC-ex, however, showed a significant reduction in all the above indexes. In vitro, treatment with cisplatin alone in NRK-52E cells resulted in an increase in the number of apoptotic cells, oxidative stress and activation of the p38 mitogen-activated protein kinase (p38MAPK) pathway followed by a rise in the expression of caspase 3, and a decrease in cell multiplication, while those results were reversed in the hucMSCs-ex-treated group. Furthermore, it was observed that hucMSC-ex promoted cell proliferation by activation of the extracellular-signal-regulated kinase (ERK)1/2 pathway. Conclusions: The results in the present study indicate that hucMSC-ex can repair cisplatin-induced AKI in rats and NRK-52E cell injury by ameliorating oxidative stress and cell apoptosis, promoting cell proliferation in vivo and in vitro. This suggests that hucMSC-ex could be exploited as a potential therapeutic tool in cisplatin-induced nephrotoxicity.