ABSTRACT
ObjectiveTo compare the therapeutical effect of exosomes derived from fibroblasts and mesenchymal stem cells on acute wound healing. MethodsPrimary human dermal fibroblasts （hDF） were isolated， cultured and identified. Human bone marrow mesenchymal stem cell exosomes （hMSC-EXO） and hDF exosomes （hDF-EXO） were extracted by ultracentrifuga tion. After 24 h of coincubation with hDF-EXO or hMSC-EXO， hDFs proliferation and migratory capacity were evaluated by cell counting kit-8 （CCK8） assay and scratch test. Full-thickness cutaneous wounds were created on 8-week-old female C57BL/6 mice， and topically applied with PBS （control）， hDF-EXO or hMSC-EXO. Wounds were measured at day 0， 2， 4， 7， and the uptake of exosomes in wound was observed at day 1. Quantitative PCR （qPCR） analysis was performed to detect the mRNA expression levels of TNF-α， IL-6， IL-1β， IL-10 in wound at day 1. HE staining was conducted to analyze the histological structure of wounds at day 7， while immunofluorescence staining was used to examine expression of PDGFR-α、α-SMA、Ki67. ResultshDF exhibited certain fibrolast-like characteristics with respect to expression of cell surface markers and specific proteins. hDF-EXO and hMSC-EXO presented exosomal morphology， size， and markers， and both concentrations were not statistically different （P>0.05）； CCK8 assay showed that both exosomes promoted hDF cell viability， compared with the negative control （P<0.01）， and hDF-EXO group had greater cell viability than hMSC-EXO group （P<0.01）. Scratch test indicated that hDF-EXO induced a significant increase in scratch healing rate versus the negative control （P<0.01）， hMSC-EXO （P<0.05）. In vivo experiments showed wound tissues took up exosomes at day 1. qPCR detected TNF-α， IL-6， IL-1β expression levels in wound at day 1 were lower in exosomes group than in the control group， and were the lowest in hMSC-EXO group （all P<0.01）. Wound areas were measured smaller at day 7 in exosomes group than in the control group （all P<0.01） and hDF-EXO group had better closure than hMSC-EXO group （P<0.05）. HE staining revealed that compared with control group， scar， incomplete epidermis and few collagen deposition remained in the hMSC-EXO group， whereas hDF-EXO group showed re-epithelialization， continuous neo-epidermis and regenerated dermis. Immunofluorescence staining suggested that the number of fibroblasts， myofibroblasts， proliferating cells was higher in both exosomes group than that in the control group， especially the highest in hDF-EXO group. ConclusionOur study shows both exosomes accelerate wound healing， whereas hDF-EXO is more effective in promoting fibroblasts proliferation， migration， transition to myofibroblasts， and hMSC-EXO may play a role in inhibiting inflammatory reaction during early stage of wound healing.