The role of mesoglycan in wound healing

Abstract

Mesoglycan is a mixture of glycosaminoglycans able to enhance some fundamental processes in wounds repair. Particularly, it promotes the re-epithelialization through the action on keratinocytes and fibroblasts and supports angiogenesis. The mechanism of action by which the mesoglycan acts in this system is not still clear. For this reason, one of the aims of my PhD project has been to study the molecular mechanism by which this mixture of glycosaminoglycans promotes tissue regeneration. The obtained in vitro data suggested that mesoglycan induced keratinocyte migration and differentiation, two important process for the correct repair of skin injury, and that some of these effects are carried out through the activation of syndecan-4/PKCα (SDC4/PKCα) pathway. Another protein involved in a wide range of physiopathological process, including cell motility and differentiation, is Annexin A1 (ANXA1). The in vitro data obtained suggested that mesoglycan is able to induce the formation of ANXA1/S100A11 complex at the inner surface of the plasma membrane and that this event is mediated by SDC4 pathway. Moreover, the results showed a role for ANXA1 in mesoglycan‐induced keratinocyte activation. It is known that SDC4 participates to the formation and secretion of microvesicles (EVs) which may contribute to wound healing. ANXA1 contained in microvesicles was able to promote keratinocytes motility and differentiation by acting on Formyl Peptide Receptors (FPRs) in autocrine manner. Thus, the extracellular form of ANXA1 may be considered as a link to intensify the effects of mesoglycan. These data contribute to the identification of an interesting autocrine loop ANXA1/EVs/FPRs in human keratinocytes, induced by mesoglycan. Furthermore, we found that EVs secreted from keratinocytes treated with mesoglycan promoted migration and invasion on fibroblasts and endothelial cells, acquiring a mesenchymal phenotype. In presence of this kind of EVs the angiogenesis appeared strongly enhanced, suggesting that EVs deriving from keratinocytes treated with the GAGs mixture, trigger a paracrine positive feedback able to further amplify the effects of mesoglycan. The third year of the PhD program, I had the opportunity to work at the William Harvey Research Institute in London, where we have used endothelial cells isolated from Wild Type (WT) and Syndecan-4 null mice (Sdc4-/-) C57BL/6 mice. We demonstrate that mesoglycan promotes cell motility and in vitro angiogenesis acting on the co-receptor SDC4. Additionally, we characterized EVs released by HUVEC cells and assessed their effect on angiogenesis. Particularly, we focused on ANXA1 containing EVs, since they may contribute to tube formation via interactions with FPRs and their bond stimulates the release of vascular endothelial growth factor (VEGFA) that interacts with vascular endothelial receptor-2 (VEGFR2) and activates the pathway enhancing cell motility in autocrine manner. Thus, we have shown that mesoglycan exerts its pro-angiogenic effects in the healing process triggering the activation of the three interconnected molecular axis: mesoglycan- SDC4, EVs-ANXA1-FPRs and VEGFA-VEGFR2... [edited by Author]