In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants

Abstract

Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/ acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp-containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm 2 ). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01 < G crit < 0.1 pmol/cm 2 ) for maximal support of the osteoblast phenotype. After 14 and 21 days, mineralization was greater on the 0.1 and 10 pmol/cm 2 bsp-RGD(15) modified implants compared to the base titanium and other control surfaces. The observed effects were attributed to specific interactions with bsp-RGD(15) and support the concept that peptide-modified implants can enhance the kinetics of differentiation of the cells they contact. These results suggest that in vivo biological performance evaluation of these biomimetic implant surfaces is merited. ß

Peri‐implant bone formation and implant integration strength of peptide‐modified p(AAM‐co‐EG/AAC) interpenetrating polymer network‐coated titanium implants

“…Briefly, a series of p(AAm-co-EG/AAc) IPN-coated implants was prepared using methods described in detail elsewhere. 3,12,13 These implants were further modified with various densities of the biomimetic bsp-RGD(15) peptide or its inact-ive analog, bsp-RGE(15) (Ac-CGGNGEPRGETYRAY-NH 2 ) ( Table I). As an additional positive control, a group of implants was coated with $50 mm thick layer of hydroxyapatite tricalcium phosphate (HA-TCP) (80% hydroxyapatite, 15% tricalcium phosphate, and 5% uncharacterized calcium phosphates) by a plasma spray technique (Zimmer, Warsaw, IN).…”

“…[3][4][5][6][7][8][9][10][11][12][13] However, only a few studies have attempted to translate these in vitro observations to relevant in vivo implant models. From these in vivo studies provide only weak evidence to support the concept that peptide-modified interfaces have a commensurate effect on wound healing in the peri-implant region.…”

“…6,32 For example, IPNcoated titanium implants functionalized with a peptide derived from rat bsp [Ac-CGGNGEPRGD-TYRAY-NH 2 , bsp-RGD (15)], demonstrated a critical ligand density (0.01 < g crit < 0.1 pmol/cm 2 ) for maximal support of the osteoblast phenotype, suggesting that further testing of the in vivo biological performance of these peptide-modified IPN surfaces was merited. 13 We adapted the rat marrow ablation model to study implant fixation in vivo with the aforementioned biomimetic coatings. This model was originally developed to study hematopoiesis 33,34 and, more recently, intramembranous bone formation [35][36][37][38] ; however, it is also an appropriate model for studies of implant fixation, since intramembranous bone formation is a basic requirement for permanent attachment of dental and orthopedic implants to the skeleton.…”

Surface engineering of titanium thin films with silk fibroin via layer‐by‐layer technique and its effects on osteoblast growth behavior

“…Immobilization of biologically active peptides (normally well known RGD containing peptides) on titanium surfaces is a common method. 10 Another surface modification approach is coating with hydroxyapatite to enhance the biocompatibility of orthopedic and dental titanium-based materials. 11,12 Alkaline treatment 13 and thermal oxidization 14 on titanium and its alloy were reported to be efficient approach to improve osteoblast growth behavior, respectively.…”

Intramembranous bone regeneration and implant placement using mechanical femoral marrow ablation: rodent models

“…As a technique with a bone regeneration end point (Figure 4), the marrow ablation model induces trabecular bone formation within the intramedullary canal in regions that, under normal conditions, lack trabecular bone. The regenerated bone induced by this model is specifically intramembranous bone, 6,39 as opposed to fracture models where the endochondral bone formation pathway is induced. 40 The marrow ablation model mimics the process of intramedullary reaming for implant placement during joint replacement surgery in humans.…”