Skin Microbiome for Differentiation of Adipose-Derived Stem Cells

Results in our recent publication in Journal of Investigative Dermatology (pii: S0022-202X(16)32239-4)demonstrate that skin commensal bacteria can exploit glycerol fermentation to produce various short-chainfatty acids (SCFAs). SCFAs can act on host cells through inhibition of histone deacetylase (HDAC). Butyricacid, one of SCFAs, has been shown to enhance preadipocyte differentiation to adipocytes via its HDACinhibitory activity. The precise mechanism in which SCFAs induce adipogenic differentiation is currentlyunclear. Activation of PPAR-γ increased the expression of perilipin A, a protein on the periphery of lipiddroplets, indicating that PPAR-γ plays a role in lipid droplet formation. Our data demonstrate that adiposederivedstem cells (ADSCs) treated with SCFAs enhanced the intracellular accumulation of Oil Red Ostained lipids and that knockdown of PPAR-γ decreased the expression of SCFA analog-induced perilipin A.These results suggest that SCFA increases the accumulation of lipid droplets and induces adipogenicdifferentiation of ADSCs via PPAR-γ.We hypothesize that the skin commensal bacteria and/or their fermentation products includingSCFAs distributed in the deep skin can stimulate the adipogenic differentiation of adipose stem cells (ASCs)through HDAC inhibition and PPAR-γ activation. Three Specific Aims are proposed to verify ourhypothesis. In Specific Aim 1, we will quantify the local concentrations of SCFAs by capillaryultrafiltration (CUF) probes in conjunction with NMR/HPLC analysis, and induce the adipogenicdifferentiation of ASC in vivo by mono-association with skin commensals in mice. In Specific Aim 2, wewill investigate the effect of SCFA deficiency on the adipogenic differentiation of ASC using germfree/SCFA-deficient mice, and measure the SCFA deficiency and decreased HDAC activity in germ-freemice. In Specific Aim 3, we will verify the requirement of HDAC inhibition for induction of adipogenicdifferentiation, and confirm the essential role of PPAR-γ in the signaling pathway of bacterial fermentation-SCFA-HDAC/PPAR-γ-adipogenesis.An injectable adipocyte filler for soft tissue augment has been developed from cultured ASCs.However, multiple questions remain regarding the viability of ASCs, the requirement of biologicalscaffolds, and the repeated injection schedule in the formation of future fat graft replacements. Ourproposal will validate the potential for SCFAs to enhance the adipogenic differentiation and the viability ofASCs, reducing the need for repeated injections, and thereby achieving a more permanent solution for softtissue augmentation.