Ligament Proteoglycans and Interactions with Collagen

Pedrini, Vittorio

Abstract

Ligaments serve important functions in mediating the proper range of motion between different skeletal structures and appear to be involved directly, or indirectly, in several orthopedic diseases (congenital clubfoot, congenital hip dislocation, idiopathic scoliosis). Despite their obvious importance ligaments are, from a molecular standpoint, largely unknown. Proteoglycans represent only a small portion of the ligament but, perhaps through interaction with collagen or because of their composition and structure, they could play an important role in the maintenance of the structural and functional integrity of this tissue. The purposes of this project are: 1) to find efficient methods to extract and purify the PG; 2) to characterize the soluble PG by chemical and physical methods in regard to: GAG and protein composition, presence or absence of cartilage type aggregates, size of monomers and, if present, aggregates, possible existence of more than one population of PG that might differ in polysaccharide and protein composition; 3) to study whether some PG are insoluble by the usual extracting techniques but can be solubilized by treatment of the tissue with collagenase and elastase; 4) to study the interactions between ligament PG and collagen by determining the effect of PG on the susceptibility of collagen to purified bacterial collagenase; the properties of collagen gels formed in the presence of PG; the effect of PG on collagen fiber formation in vitro. We plan to use the patellar and lateral ligaments of dogs in this phase of our study, since these tissues can be easily obtained. The knowledge acquired from animal tissue will later be applied to the study of human normal and diseased ligaments.