Collagen fiber formation: Effect of proteoglycans

Connective tissues are composed of fibrous and non-fibrous components. Collagen and elastic fibers are fibrous components and other composite macromolecules termed proteoglycans (PGs) and glycosaminoglycans (GAG) constitute the non-fibrous components. My studies indicate that dextran sulfate, an analog of the sugar component of GAGs inhibits collagen type I fiber formation. Birefringence retardation measurements show that addition of GAGs and PGs decreases collagen fiber organization. This may either be a result of PGs and GAGs binding to the fiber nucleus and causing a change in the growth process or they may be affecting the aggregation process. In the presence of GAGs, collagen fiber diameter is increased and the ultimate tensile strength is decreased. Whereas, in the presence of PG1, a high density proteoglycan from articular cartilage, the fiber diameter is increased but the ultimate tensile strength is increased. The effect of GAGs (dermatan sulfate and chondroitin sulfate) and PGs (PG1 and CS-PG) on physico-chemical and mechanical properties of reconstituted collagen type I fiber formation was studied by measuring fiber diameter, birefringence retardation and mechanical testing.