Wound Healing Society

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Exosomes Derived From Dermal Fibroblasts Define The Intrinsic Variability In Wound Healing Responses
Hima Vangapandu1, Natalie Templeman1, Daniel Colchado1, Alexander Blum1, Hui Li1, Xinyi Wang1, Emily Steen1, Paul Bollyky2, Sundeep Keswani1, Matthew Robertson1, Cristian Coarfa1, Swathi Balaji1.
1Baylor College of Medicine, Houston, TX, USA, 2Stanford University, Palo Alto, CA, USA.

Wound responses involve fibroblast(FB)-mediated scar formation potentiated by mechanical tension. The heterogeneity observed in fibrosis in different individuals in response to similar injuries is yet to be accounted for. Exosomes play a pivotal role in mediating cell communication which governs scarring. We hypothesize that FB-derived exosomes drive differential scar forming abilities in response to tension , which contributes to the human heterogeneity in scarring responses. Skin and paired scar tissue was obtained from women with C-section scars who underwent abdominoplasty. Patient-scars were classified as ‘high’ and ‘low’ based on VSS. FBs isolated from scars and corresponding normal skin were cultured on silicone membranes +/-10% static strain(24hrs). Changes in proliferation(Ki67) and fibrogenic potential(fibrosis array) among low(n=3) and high scarrers(n=3) were determined. Exosomes isolated from these different FBs were evaluated using next generation sequencing(NGS), and adoptively transferred into SCID murine skin-wounds, and wound repair was evaluated. p-values by ANOVA. Scar FBs from high scarrers had higher proliferation than their normal counterparts, and conversely, normal FBs from low scarrers proliferated faster than their scar FBs(p<0.05). Expression of several profibrotic genes COL3A1, TGFb3, MYC and PDGFA were upregulated in high scarring normal FBs as compared to low scarrers. NGS revealed significant differences between the FB exosomal-miRNA from normal skin and scar of high and low scarrers, which were further pronounced under mechanical tension. More miRNAs were downregulated(n=54) in low scarring normal FBs than upregulated(n=11) in response to tension, whereas as similar numbers of miRNA were downregulated(n=41) as upregulated(n=31) in high scarrers. Several miRNAs changed in opposite directions in high versus low scarring normal-FBs under tension. Low and high-scar FB-derived exosomes induced a corollary severity in scarring in SCID wounds Our results demonstrate that there are intrinsic differences in different individuals and how they respond to tension mediated by exosomes that could influence fibrogenic phenotype.

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