Early Stages of Ex Vivo Collagen Glycation Disrupt the Cellular Interaction and Its Remodelling by Mesenchymal Stem Cells—Morphological and Biochemical Evidence

Mesenchymal stem cells (MSCs), whose main function is tissue repair, use collagen to restore the structural integrity of damaged tissue, maintaining its organization through concomitant remodelling. The non-enzymatic glycation of collagen is likely to compromise its communication with MSC, which indeed underlies various pathological conditions such as late complications of diabetes and aging. However, data on the effect of more early stages of collagen glycation on the MSC interaction are lacking. This study focused on the fate of in vitro glycated rat tail collagen (RTC) in contact with MSCs after its pre-exposure to glucose for 1 or 5 days. Using human adipose tissue-derived MSCs (ADMSCs), we showed that their interaction with glycated collagen is significantly altered, manifested morphologically by reduced cell spreading, less formation of focal adhesions, and weaker development of the actin cytoskeleton, further confirmed by ImageJ morphometric analysis. This suggests a poorer recognition of early glycated collagen by integrin receptors, possibly due to steric hindrance of their binding sites. These morphological events were also accompanied by greatly reduced fibril-like reorganization of adsorbed FITC-collagen (a sign of impaired remodeling), complemented by reduced sensitivity to proteases. The latter was confirmed in two ways: measuring directly FITC-collagen degradation by the attached cells and quantifying the proteolysis reduction upon exogenous addition of collagenase in a cell-free system. The mechanism of the observed effects is unclear, although differential scanning calorimetry confirmed the presence of weak structural changes in glycated collagen. All this led us to conclude that the reason for the morphological changes of ADMSCs is the impaired interaction with early-glycated collagen due to the hindrance of complementary sequences for integrins, which certainly also affects the mechanical remodeling of collagen. However, the impaired collagenolytic activity, together with the observed small changes in the thermal transition profile, undoubtedly indicate some internal changes in the structural organization of the collagen molecule occurring even at this early stage of glycation, which in turn contributes further to the impaired MSC remodeling activity.