Dermatopontin Reduces Adhesion of Bone Marrow and Endothelial Cells in Vitro

Abstract

Dermatopontin (DPT) is a small, non-collagenous, and extracellular matrix-associated protein that has not been well characterized. We have previously demonstrated that DPT is secreted by adipocytes in the bone marrow. We have also shown that it can negatively regulate hematopoietic stem cell (HSC) homing and engraftment in mice, but the mechanism by which it does so remains to be elucidated. In this study, we found that DPT reduced adhesion of whole bone marrow (WBM) and endothelial cells in a dose-dependent manner. Interestingly, when WBM cells were incubated with DPT it reduced their ability to adhere on top of endothelial cell monolayers. And using a novel release assay, we also demonstrated that DPT could release WBM cells that were already adhered to the endothelial cells. Based on these studies, we hypothesize that DPT is delaying HSC homing and engraftment by interacting with or disrupting integrin receptors that are critical for transmigration across the endothelial barrier.