Osteoconductivity of bone substitutes using maxillary bone marrow osteoprogenitor cells

Objectives: In this study we demonstrate a new approach by which in vitro and in vivo assays are used to screen bone substitutes for their osteoconductivity. The screening is done using local osteoprogenitors (bone-producing cells) isolated from schneiderian membrane and maxillary tuberosity bone marrow. Methods: In the present study, the osteoconductive potential of the different bone graft materials or substitutes available in the market, e.g. Bio-Oss, Bi-Ostetic, OraGraft (allograft), and Pro-Osteon, was examined. The AlamarBlue™ Metabolic Activity Assay (Serotec, USA) was used to determine the adhesion of cells seeded on the different bone substitutes and to determine how these materials affect the proliferation abilities of the cells seeded on them.Samples of the different bone substitutes seeded with MSSM or Maxillary derived osteoprogenitors and co-cultured for 14 days were taken for SEM (n=3) assessment. 8-weeks-old athymic nude mice were used for in vivo ectopic transplantation. All mice were euthanized 8 weeks after transplantation.The harvested transplants were prepared for histolgy and were used for histomorphometry measurements using Image Pro plus 6 computerized analysis system. Results: The adherence of these cells to bone substitutes and their proliferation , tested in vitro, has been shown to be most optimal in bone graft materials, first in OraGraft (allograft) and then in Pro Osteon. In vivo bone formation, within the bone graft, was also observed to be best using OraGraft and Pro-Osteon. Conclusions: Testing the osteoconductivity of these bone graft substitutes in vitro and in vivo has shown that the method is simple and informative for the purpose of screening biomaterials currently in use for sinus augmentation procedures. Ectopic osteoconductivity of the biomaterials seeded with the cells chosen for bone formation proved to be a technique useful for screening and thus to optimally select osteoconductive biomaterial for sinus augmentation.