Cyclo-DfKRG peptide modulates in vitro and in vivo behavior of human osteoprogenitor cells on titanium alloys

The first aim of the present study was to investigate the capacity of a cyclo-DfKRG-coated hydroxyapatite–titanium alloy (Ti–HA–RGD) to activate in vitro human osteoprogenitor cells adhesion and differentiation. The second purpose was to examine in vivo the role of a autologous cell seeding on cyclo-DfKRG-functionalized materials to provide bone repair after implantation in femoral condyle of rabbits. vitro results have demonstrated that both titanium alloy functionalized with hydroxyapatite (Ti–HA–RGD and Ti–HA) contributed to higher cell adhesion than titanium alloy alone respectively 85 and 55% vs 15% compared to tissue culture polystyrene after one hour of cell seeding. differentiation, after 3 days of culture, Ti–HA presented the highest increase of ALP mRNA of all surfaces studied. Ti–HA–RGD showed an intermediate value about half as high as Ti–HA. Moreover after 3 days, both Ti–HA and Ti–HA–RGD surfaces showed the highest increase of cbfa1 mRNA expression. eks following implantation, in vivo findings revealed that percentage of lacunae contact observed with pre-cellularized Ti–HA–RGD samples remains significantly lower than with Ti–HA group (10.5 ± 9.6 % vs 33.7 ± 11.5 %, P < 0.03). Meanwhile, RGD peptide coating had no significant additional effect on the bone implant contact and area. Moreover, histomorphometry analysis revealed that implantation of pre-cellularized RGD coated materials with ROP cells increased significantly peri-implant fibrous area (24 ± 11.6% vs 3 ± 1.7% for Ti–HA–RGD, P < 0.02). RGD coatings demonstrated osteoblastic adhesion, differentiation and in vivo bone regeneration at most equivalent to HA coatings.