Autologous micrograft accelerates endogenous wound healing response through ERK-induced cell migration

Abstract

Defective cell migration causes delayed wound healing (WH) and chronic skin lesions. Autologous micrograft (AMG) therapies have recently emerged as a new effective and affordable treatment able to improve wound healing capacity. However, the precise molecular mechanism through which AMG exhibits its beneficial effects remains unrevealed. Herein we show that AMG improves skin re-epithelialization by accelerating the migration of fibroblasts and keratinocytes. More specifically, AMG-treated wounds showed improvement of indispensable events associated with successful wound healing such as granulation tissue formation, organized collagen content, and newly formed blood vessels. We demonstrate that AMG is enriched with a pool of WH-associated growth factors that may provide the starting signal for a faster endogenous wound healing response. This work links the increased cell migration rate to the activation of the extracellular signalregulated kinase (ERK) signaling pathway, which is followed by an increase in matrix metalloproteinase expression and their extracellular enzymatic activity. Overall we reveal the AMG-mediated wound healing transcriptional signature and shed light on the AMG molecular mechanism supporting its potential to trigger a highly improved wound healing process. In this way, we present a framework for future improvements in AMG therapy for skin tissue regeneration applications.

Activator Protein-1 Transcriptional Activity Drives Soluble Micrograft-Mediated Cell Migration and Promotes the Matrix Remodeling Machinery

“…In both Taken together, we demonstrate that posttranslational activity of both Fra-1 and c-Jun in fibroblasts and keratinocytes is increased upon soluble MG treatment. This suggests that these AP-1 members are involved in the molecular mechanism of MG treatment and in the previously shown accelerated AMG-dependent wound healing [19].…”

“…A recent study indicated that increased autologous micrograft-(AMG-) mediated fibroblast migration requires activation of the ERK signaling pathway that has been shown to be induced by the growth factors present in the soluble fraction of the micrograft [19]. To identify the transcriptional regulators mediating this behavior, we made use of the DEGs of wounded adult murine fibroblasts treated with the noncellular fraction of the micrograft treatment [19]. These genes were subsequently integrated in a gene regulatory network analysis using the iRegulon analysis software [24] (Figure 1(a)).…”

“…Recently, a novel MG technique has emerged as an innovative and affordable wound treatment whereby skin tissues are ground into a resulting solution of 80 μm microtissue fragments containing tissue-residing progenitor cells and matrix components [18]. Moreover, a recent study has shown that skin injury treatment with the soluble MG fraction deprived of tissue-residing cells and highly enriched in growth factors (such as IGF-1 and bFGF) is sufficient to promote the endogenous regenerative capacity of the skin by accelerating wound closure, showing increased reepithelialization, and increasing granulation formation and increased CD31 + vessel formation [19].…”

“…Recently, the extracellular signal-regulated kinase (ERK) signaling pathway has been identified as one of the main drivers of the molecular mechanism behind this technique [19]. Upon MG treatment, both fibroblasts and keratinocytes displayed high levels of phosphorylated ERK (p-ERK) and exhibited upregulated transcription of MMPs.…”

“…In this work, we dissect the molecular regulatory network behind the accelerated cell migration obtained by the MG treatment. To unveil key transcriptional regulators involved in the ameliorating effects mediated by this therapy, we integrated differentially expressed genes (DEGs) obtained upon a 5 h treatment with the noncellular micrograft solution into a gene regulatory network analysis (GSE123829) [19]. Interestingly, MG-dependent DEGs appeared to be likely regulated by important members of the AP-1 transcription factors, such as Fra-1.…”