Proteoglycans At the Bone-Implant Interface

Abstract

The widespread success of clinical implantology stems from bone's ability to form rigid, load-bearing connections to titanium and certain bioactive coatings. Adhesive biomolecules in the extracellular matrix are presumably responsible for much of the strength and stability of these junctures. Histochemical and spectroscopic analyses of retrievals have been supplemented by studies of osteoblastic cells cultured on implant materials and of the adsorption of biomolecules to titanium powder. These data have often been interpreted to suggest that proteoglycans permeate a thin, collagen-free zone at the most intimate contact points with implant surfaces. This conclusion has important implications for the development of surface modifications to enhance osseointegration. The evidence for proteoglycans at the interface, however, is somewhat less than compelling due to the lack of specificity of certain histochemical techniques and to possible sectioning artifacts. With this caveat in mind, we have devised a working model to explain certain observations of implant interfaces in light of the known physical and biological properties of bone proteoglycans. This model proposes that titanium surfaces accelerate osseointegration by causing the rapid degradation of a hyaluronan meshwork formed as part of the wound-healing response. It further suggests that the adhesive strength of the thin, collagen-free zone is provided by a bilayer of decorin proteoglycans held in tight association by their overlapping glycosaminoglycan chains.

Genetic Networks in Osseointegration

“…The interface between the implant surface and bone consists of an amorphous layer containing PG and a layer with randomly aligned collagen filaments (Albrektsson et al, 1983), although the amount of PG in the interface zone has been debated (Klinger et al, 1998;Palmquist et al, 2010). PG is functionally modified with glycosaminoglycan side chains, and it has been reported that the adhesion of in vitro mineralized tissue to Ti discs was attenuated by treatment with chondroitinase AC, chondroitinase B, or keratinase (Nakamura et al, 2006), which suggests a functional role of glycosaminoglycans/PGs in bone adhesion to the implant surface.…”

Biological nano-functionalization of titanium-based biomaterial surfaces: a flexible toolbox

“…Bone sialoprotein and osteopontin are involved in cell binding to mineralized bone (Sodek et al 1992). And, finally, proteoglycans and their sugar components should be mentioned as compounds involved in interactions between collagen, growth factors and cells (Klinger et al 1998). …”

Surface Aspects of Titanium Dental Implants

“…The molecular and cellular events at the bone-implant interface are well described in Puleo &Nanci, 1999 andKasemo, 2002 but many crucial aspects are still far from being understood (Kasemo, 2002;Puleo & Nanci, 1999). Although our knowledge regarding the molecular structure of the bone-implant interface has evolved much in the last decade there are still many uncertainties (Klinger et al, 1998).…”