Preparation and characterization of an advanced medical device for bone regeneration

Abstract

Tridimensional scaffolds can promote bone regeneration as a framework supporting the migration of cells from the surrounding tissue into the damaged tissue and as delivery systems for the controlled or prolonged release of cells, genes, and growth factors. The goal of the work was to obtain an advanced medical device for bone regeneration through coating a decellularized and deproteinized bone matrix of bovine origin with a biodegradable, biocompatible polymer, to improve the cell engraftment on the bone graft. The coating protocol was studied and set up to obtain a continuous and homogeneous polylactide-co-glycolide (PLGA) coating on the deproteinized bone matrix Orthoss® block without occluding pores and decreasing the scaffold porosity. The PLGA-coated scaffolds were characterized for their morphology and porosity. The effects of PLGA polymer coating on cell viability were assessed with the 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyl-2H-tetrazolium assay. The polymer solution concentration and the number of polymeric layers were the main variables affecting coating efficiency and porosity of the original decellularized bone matrix. The designed polymer coating protocol did not affect the trabecular structure of the original decellularized bone matrix. The PLGA-coated decellularized bone matrix maintained the structural features, and it improved the ability in stimulating fibroblasts attachment and proliferation.

Fig. 1

Scheme of a single cycle of the Orthoss® set up coating process

Fig. 2

DOE elaboration of process variables: a standardized Pareto chart and b results of surface response

Fig. 3

Effect of coating polymer concentrations on fibroblast cells seeding (single-coating layer and soaking time, 30 min)

Fig. 4

Effect of soaking time on fibroblast cells seeding (single-coating layer and polymer solution concentration, 4% (w/v))

Fig. 5

Effect of polymer layer number on fibroblast cells seeding (polymer solution concentration, 4% (w/v) and soaking time, 30 min)

Fig. 6

SEM images of PLGA-coated Orthoss® block: a trabecular pattern and porosity at ×31 magnifications; b outer surface at ×1.85 K magnifications c inner surface at ×1.85 K magnifications, and d inner surface at ×8.27 K magnifications

Fig. 7

Results of cells proliferation study (polymer solution concentration, 4% (w/v), soaking time, 30 min, and one-coating cycle)

Fig. 8

Confocal microscopy images of fibroblasts cell proliferation on PLGA-coated scaffolds at different incubation times. Cell proliferation on the uncoated scaffolds at 7 days is reported as reference