Abstract Body:
Background: Hyaluronan (HA) accumulates after tissue injury and may regulate the wound-healing process. We found that HA is increased in and around the scar following myocardial infarction (MI). Fibroblasts are the main producers of the collagen that comprises the scar, and we have shown that they are responsible for HA accumulation. Given that these two extraordinarily high-volume synthetic processes occur in the same place and simultaneously, we queried whether alterations in Has2-dependent HA synthesis impacted collagen secretion and other fibroblast functions.

Goal: To determine the impact of HA synthesis on fibroblast function.

Methods and Results: We isolated cardiac fibroblasts from Has2^fl/fl mice and treated with Cre adenovirus to delete Has2 expression or Has2 adenovirus to overexpress Has2. We assessed cell number and found no differences when Has2 was deleted or overexpressed in both naïve fibroblasts (n=6); activation with TGF-b did not change this response. We used a scratch assay to assess migration and found no change between treatments in naïve fibroblasts (n=6). Hydroxyproline assessment of deposited collagen and immunoblotting for soluble collagen secretion in the media indicated no differences between treatments in naïve fibroblasts (n=3).

Conclusion: Genetic manipulation of HA production did not impact proliferation, migration, or collagen secretion in fibroblasts. Considering the enormous metabolic requirement of fibroblasts to produce HA and collagen, these results suggest that the regulation of these processes may be distinct or that the substrate is not limiting in our experimental conditions. In the intact heart, substrate could become limiting and a relationship between these two biosynthetic processes may emerge