In vitro pathological model of osteopenia to test orthopaedic biomaterials

The association of in vitro tests and in vivo bone implants, has significantly improved the characterization of biomaterials for orthopaedic devices before their clinical use. However, neither cell cultures nor most animals models used for these tests entirely reflect the clinical conditions in which biomaterials are implanted. Pathological animal models are considered to substantially improve our knowledge of osteointegration of biomaterials; for this reason researchers increasingly use aged, osteopenic or arthritic animals in their experimental tests. The development of "pathological cell cultures" would also be of great importance for the study of biomaterials. It would allow a complete material evaluation, beginning with a biocompatibility test to a more finalized and specific preclinical evaluation. The present study, looks at the possibility of using cell culture methodology for the improvement of in vitro biomaterials characterization in the case of osteopenia. Cultures derived from normal (NB-OST) rats were compared to those of osteopenic (OB-OST) rats, by testing the osteoblasts against common parameters of characterization. Moreover, the reaction of these cultures to two biological glasses of known in vivo behavior (both in normal and osteopenic bone) by means of parameters on biocompatibility and bone formation index, was evaluated. Our results showed that there was no evidence of differences between the NB-OST and OB-OST cultures. After 6 days of culturing, the bioglass that did not osteointegrate in osteopenic animals, did not induce cytotoxicity in NB-OST, but a significative reduction of viability and Osteocalcin level in OB-OST was observed. We think that these data should stimulate researchers to develop further tests in order to improve preliminary in vitro comprehension on biomaterials.