Properties of in vitro and in vivo of a new absorbable polymer and allogeneic bone composite

Properties in vitro and in vivo (rabbit, guinea pig, mouse) of a new absorbable polymer and allogeneic bone composite for bone regeneration and orthopedic implants.

Currently, there is no bone fixation material that could fully replace competent host bone. The gradual replacement of bone graft by host bone is a result of its unique potential associated with the presence of bone morphogenetic proteins (BMPs). However, the size of human bone limits the use of alloplastic implants for surgical (orthopedic) fixation.

The aim of this project was to develop a new composite material for bone regeneration, consisting of powder derived from human bone obtained from a tissue bank and an absorbable polymer (13% by weight of bone powder in medical-grade polylactide). Such a biomaterial could possess osteoinductive properties and be used for manufacturing bone fixation implants of various shapes and sizes.

Samples:

Samples were obtained by tape casting and film pressing, then subjected to radiation sterilization with a dose of 35 kGy. Two cell lines – normal mouse embryo fibroblasts (Balb 3T3/c) and human fetal osteoblasts (hFOB 1.19) – were cultured with biomaterial extracts (MTT assay) or in indirect contact with the evaluated biomaterials (agar diffusion method). Additionally, cell viability was assessed after 5 days of incubation with the biomaterial using ThinCert tissue culture inserts. Subsequently, the following in vivo studies were conducted: acute systemic toxicity, skin irritation and sensitization, and local effects after implantation.

Test results:

The results of in vitro cytotoxicity tests conducted on Balb 3T3/c and hFOB 1.19 cells are presented in Figures 1, 2, and 3. All selected methods met the criteria for CN and CP response according to the guidelines. Results estimated using the MTT assay showed that cell viability after 24, 48, and 72 hours of incubation with extracts of the evaluated biomaterial ranged from approximately 88% to 108% compared to control groups C and CN.