Engineered porous scaffold for periprosthetic infection prevention

Abstract

Event Abstract Back to Event Engineered porous scaffold for periprosthetic infection prevention Giorgio Iviglia1, 2, Clara Cassinelli1, Elisa Torre1, Francresco Baino2*, Marco Morra1* and Chiara Vitale Brovarone2* 1 Nobil Bio Ricerche srl, R&D, Italy 2 Politecnico di Torino, Department of Applied Science and Technology, Italy Introduction: Periprosthetic infection (PPI) is a devastating consequence of implant insertion involving 1% - 5% of procedures[1],[2]. Strategies to PPI prevention involve either increasing the rate of new bone formation or the release of antibiotics such as vancomycin. Modern surface-engineering approaches allow to combine these strategies: an innovative three-dimensional porous scaffold using HA and β-TCP, coupled with pectin(PEC)-chitosan(CHIT) polyelectrolite (PEI), loaded with vancomycin (VCA) was developed. By this approach, it is possible to achieve a controlled vancomycin release, inhibiting the bacterial growth until 1 week, and promoting bone formation in vitro. Materials and Methods: All materials used were purchased from Sigma-Aldrich. A slurry was prepared by mixing the HA/ β-TCP (25:75 % wt.) powder, binding agent, dispersing agent and water. Polyurethane sponge impregnation method was used[3]. Sintered scaffold was filled with a solution of Pectin-Vancomycin (1% wt - 5% wt), freeze-dried and then a Chitosan functionalization was made in order to generate a polyelectrolite structure on ceramic surface.Physiochemical and biological properties were analyzed by SEM, micro-CT, XPS,HPLC drug release, mechanical and degradation test, RT-PCR and in vitro osteoblast cell culture. Results and Discussion: Usually periprosthetic zone exhibits an acidic environment, engineered PEC-CHIT-VCA functionalization provides an excellent protection at pH 3, only 9% of mass was lost after 4 days and the efficacy was mantained. Drug release test, combined with serial bacterial dilution test demonstrated that the system HA/ β-TCP – PEC-VCA-CHIT yields a controlled release during 1 week, unlike HA/ β-TCP - VCA and HA/ β-TCP - PEC-VCA that shown a “burst” release in less than 24h. The Agar germ test confirmed that the entrapped antibiotic is able to inhibit the growth and proliferation of Staphylococcus epidermidis. RT-PCR on Engineered scaffold of macrophages cell culture after 4 h, shown a decrease of fold expression for Interleukin1β and MCP-1 genes, and a conseguent increase of Interleukin 10, proving that PEC-CHIT-VCA treatement elicits anti-inflammatory responses. Since fibroblast from gingiva proliferate faster than osteoblast, the PEC-CHIT-VCA coating was studied in order to avoid early infiltration, but the linear degradation rate of PEI guide bone regeneration, exposing porous ceramic phase to osteoblast, pro-osteogenics response was further demonstrated by SAOS-2 osteoblast, after 24h, 72h and 5 days of cell culture, SEM analysis shows a good cell infiltration, and RT-PCR shown a increasing in pro-osteogenic genes, as ALP and OCN. Conclusion: By coupling a bio-ceramic scaffold and a polyelectrolyte polysaccharide, a complex biomimetic bone substitute which reduce inflamation, and promotes cell infiltration and proliferation was obtained. The PEC-VCA-CHIT formulation allows to obtain high concentration of antibiotic in situ with a controlled and prolonged release. HA/βTCP-PEC/VCA /CHIT could then represent an ideal system to struggle against PPI in dental applications, by stimulating new bone formation and inhibiting bacterial growth.