A biphasic response of polymerized Type 1 collagen architectures to dermatan sulfate

Abstract

Collagen I, the most abundant extracellular matrix (ECM) protein in vertebrate tissues provides mechanical durability to tissue microenvironments and regulates cell function. Its fibrillogenesis in biological milieu is predominantly regulated by dermatan sulfate proteoglycans, proteins conjugated with iduronic acid-containing dermatan sulfate (DS) glycosaminoglycans (GAG). Although DS is known to regulate tissue function through its modulation of Coll I architecture, a precise understanding of the latter remains elusive. We investigated this problem by visualizing the fibrillar pattern of fixed Coll I gels polymerized in the presence of varying concentrations of DS using second harmonic generation microscopy. Measuring mean second harmonic generation signal (which estimates the ordering of the fibrils), and surface occupancy (which estimates the space occupied by fibrils) supported by confocal reflectance microscopy, our observations indicated that the effect on fibril pattern of DS is contextual upon the latter's concentrations: Lower levels of DS resulted in sparse disorganized fibrils; higher levels restore organization, with fibrils occupying greater space.An appropriate change in elasticity as a result of DS levels was also observed through atomic force microscopy. Examination of dye-based GAG staining and scanning electron microscopy suggested distinct constitutions of Coll I gels when polymerized with higher and lower levels of DS. We observed that adhesion of the invasive ovarian cancer cells SKOV3 decreased for lower DS levels but was partially restored at higher DS levels. Our study shows how the Coll I gel pattern-tuning of DS is of relevance for understanding its biomaterial applications and possibly, pathophysiological functions.

Extracellular matrix as a driver for intratumoral heterogeneity

“…Desmoplastic changes are the result of collagen deposition and signify a more aggressive progression [20]. Collagen patterning and fibrillogenesis are also sensitive to other ECM constituents: sulphated proteoglycans such as decorin and biglycan are known to bind to collagen using their protein cores, whereas their hydrophilic glycosaminoglycan (GAG) chains alter the kinetics and geometry of fibrillogenesis [21,22]. Chondroitin and dermatan sulfate polymers may also show self-association, which provides insights into how different levels of such GAGs could alter their miscibility with polymerizing collagen fibrils, leading to heterogeneously patterned and constituted ECM across spatial scales [23].…”

“…On the other hand, collagen fiber alignment has been shown to regulate not just migration, but also MMP secretion and invadopodia kinetics [64]. The presence of dermatan sulfates in collagen I scaffolds alters their alignment properties (as detected using second harmonic imaging) leading to changes in networklike behaviors of the aggressive SKOV3 ovarian cancer cells [21]. Macroscale architectural differences in tissues may deeply influence cancer progression: Paul and co-workers show how the disordered blood vessel topography of the caudal vascular plexus in zebrafish predispose colonization of intravasated breast and mammary cancer cells relative to the linear topographic arrangement of a less preferred organotypic site: the brain [65].…”

“…The effect of changes in storage modulus on cell spreading and proliferation have shown that softer substrata are inhibitive to such processes. In addition to compositional complexity, stiffness of ECM too tunes phenotypes such as proliferation, migration, progenitory potentials and sensitivity to drugs in ovarian and breast cancers [21,67]. In the context of ovarian cancer, stiffness of the ECM microenvironment has been observed to increase cell migration in a FAK-dependent manner and disaggregation of spheroids constituted from the aggressive SKOV3 cell lines [68].…”