An Exosome-Rich Conditioned Medium from Human Amniotic Membrane Stem Cells Facilitates Wound Healing via Increased Reepithelization, Collagen Synthesis, and Angiogenesis

Abstract

Tissue regeneration is an essential requirement for wound healing and recovery of organs’ function. It has been demonstrated that wound healing can be facilitated by activating paracrine signaling mediated by exosomes secreted from stem cells, since exosomes deliver many functional molecules including growth factors (GFs) and neurotrophic factors (NFs) effective for tissue regeneration. In this study, an exosome-rich conditioned medium (ERCM) was collected from human amniotic membrane stem cells (AMSCs) by cultivating the cells under a low oxygen tension (2% O2 and 5% CO2). The contents of GFs and NFs including keratinocyte growth factor, epidermal growth factor, fibroblast growth factor 1, transforming growth factor–β, and vascular endothelial growth factor responsible for skin regeneration were much higher (10–30 folds) in the ERCM than in normal conditioned medium (NCM). In was found that CM–DiI-labeled exosomes readily entered keratinocytes and fibroblasts, and that ERCM not only facilitated the proliferation of keratinocytes in normal condition, but also protected against H2O2 cytotoxicity. In cell-migration assay, the scratch wound in keratinocyte culture dish was rapidly closed by treatment with ERCM. Such wound-healing effects of ERCM were confirmed in a rat whole skin-excision model: i.e., the wound closure was significantly accelerated, remaining minimal crusts, by topical application of ERCM solution (4 × 109 exosome particles/100 μL) at 4-day intervals. In the wounded skin, the deposition of collagens was enhanced by treatment with ERCM, which was supported by the increased production of collagen-1 and collagen-3. In addition, enhanced angiogenesis in ERCM-treated wounds was confirmed by increased von Willebrand factor (vWF)-positive endothelial cells. The results indicate that ERCM from AMSCs with high concentrations of GFs and NFs improves wound healing through tissue regeneration not only by facilitating keratinocyte proliferation for skin repair, but also activating fibroblasts for extracellular matrix production, in addition to the regulation of angiogenesis and scar tissue formation.

Preclinical and Clinical Studies on the Use of Extracellular Vesicles Derived from Mesenchymal Stem Cells in the Treatment of Chronic Wounds

“…The study suggested that ERCM with its rich content of GFs and NFs could be a potential candidate for clinical trials aimed at managing various acute and chronic skin conditions. 94 In the realm of chronic wounds, a significant amount of research has been directed toward leveraging MSC-EVs to boost the healing process, with a particular focus on diabetic wounds. These studies suggest that harnessing mesenchymal stem cell-derived EVs shows great potential in addressing chronic diabetic wounds.…”

“…Results from in vitro and in vivo studies showed that ERCM from AMSCs enhanced skin wound healing, reduced scar formation, and promoted reepithelialization, collagen synthesis, and angiogenesis. The study suggested that ERCM with its rich content of GFs and NFs could be a potential candidate for clinical trials aimed at managing various acute and chronic skin conditions …”