Phenotypic Differences in Adult and Fetal Dermal Fibroblast Responses to Mechanical Tension

ObjectiveFetal regenerative wound healing is characterized by hyaluronan(HA)-rich microenvironment and fibroblasts that produce pericellular matrices(PCM) abundant in high molecular weight HA. Recent studies showed that while small wounds in fetal skin heal regeneratively, large wounds heal with fibrosis. We posit large wounds generate higher mechanical tension which alters HA metabolism in the fetal fibroblasts and lead to a pro-fibrotic phenotype. ApproachC57BL/6J murine fetal (FFB; E14.5) and adult (AFB; 8wk) dermal fibroblasts were subjected to +/-10% tonic strain. Changes in PCM, HA enzymes and molecular weight, and fibrotic gene expression were measured. ResultsFFB pericellular matrix reduced upon exposure to increased tension, and the HA profile shifted from high to lower molecular weight. Under static conditions, AFB had higher expression of HA synthases (HAS) 1 and 2 and degradation enzymes KIAA1199, HYAL1, and TMEM2 than FFB, suggesting more HA turnover in AFB. Tension resulted in an increase in HAS1, HAS3, KIAA1199, and HYAL2 expression and a decrease in HAS2 and TMEM2 expression in FFB. CD26, a marker associated with scar production, increased in FFB under tension, along with altered fibrotic gene expression profile and reorganized cytoskeletal f-actin and increased -SMA that resembled AFB. InnovationThis study elucidates the differences in how biomechanical tension alters HA metabolism and fibrotic phenotype of FFB vs AFB, providing further understanding of the fetal regenerative wound healing phenotype. ConclusionUnderstanding the intrinsic differences in HA metabolism and fibrotic phenotype among FFB and AFB in response to wound mechanical stimuli may yield new insights to promote regenerative wound healing.