Amino acid coated UHMW-PE implants modify neovascularization in the tissue-implant response

Polyethylene materials used in orthopedic applications are biocompatible and non-immunogenic with host tissues. Recent studies in our laboratory have demonstrated the need to further study neovascularization associated with these devices in vivo to adequately elucidate methods to modulate the tissue-implant response. The purpose of this investigation was to determine differences in neovascularization after implantation of ultra-high molecular weight polyethylene (UHMW-PE) rinsed with saline (control) or coated with poly-L-lysine (PLL), arginine-glycine-aspartic acid (RGD), or arginine-glycine-glutamic acid (RGE) into 16 adult male rats intraperitoneally (I/P). Implants and surrounding tissue were harvested at 90 days post-implantation. The animals were euthanized; and the UHMW-PE implants and the fibrous tissue capsules surrounding them were harvested. Microscopic examination of routinely stained sections (5 microns, Hematoxylin & Eosin) of the fibrous tissue capsules revealed blood vessel counts were highest in the PLL coated group (19 ± 3.27 cells/high power field). There was a decreased mean number of blood vessels per high power field for saline (17.23 ± 4.57), RGE (2.81 ± 1.50), and RGD (2.56 [+ or -] 1.55). Analyses revealed blood vessel counts were significantly higher in saline and PLL treated group compared to RGD and RGE groups (ANOVA, p < 0.05). These findings indicate neovascularization in the fibrous tissue surrounding UHMW-PE can be reduced using amino acid combination coatings. In addition, these results provide evidence that the neovascularization can be modulated to some extent using amino acid coatings in soft tissue applications. Keywords: polyethylene, amino acid coating, implant, soft-tissue, biocompatibility, angiogenesis
INTRODUCTION Neovascularization is the process of new blood vessel formation from existing vasculature and occurs in the tissue-implant interaction. Though widely used in orthopedic applications such as hip and knee [...]