Effect of rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins in vitro.

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation because it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins by human bone-derived cells (HBDCs) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, two materials with a crystalline phase Ca(2)KNa(PO(4))(2) and with a small amorphous portion containing either magnesium potassium phosphate (material denominated GB14) or silica phosphate (material denominated GB9), and a calcium phosphate bone cement (material denominated Biocement D). HBDCs were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All substrates supported continuous cellular growth for 21 days. In the presence of GB14 and Biocement D specimens cell proliferation was reduced and cell differentiation increased. At day 21, the greatest number of cells was found on GB9 expressing significantly higher levels of bone-related proteins than cells grown on all other surfaces. Because all novel materials facilitated the expression of the osteoblastic phenotype at least as much as TCP and the polystyrene control, these biomaterials can be regarded as excellent candidate bone substitute materials. GB9 induced the highest proliferation and cellular differentiation after 21 days of incubation, suggesting that this material may possess a higher potency for enhancing osteogenesis than TCP.