The functional expression of human bone-derived cells grown on rapidly resorbable calcium phosphate ceramics

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation, since it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates on the expression of bone-related genes and proteins by human bone derived cells (HBDC) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, and four materials created from beta-Rhenanite and its derivatives: R1-beta-Rhenanite (CaNaPO4); R1/M2 - composed of CaNaPO4 and MgNaPO4; R1+SiO2 composed of CaNaPO4 and 9% SiO2 (wt%); and R17 - Ca2KNa(PO4)(2). HBDC were grown on the substrata for 3, 5, 7, 14 and 21 days and probed for Type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase and bone sialoprotein mRNA and proteins. All substrata supported continuous cellular growth for 21 days when R1+SiO2 and R17 had the highest number of HBDC. At 14 and 21d, cells on R1 and on R1+SiO2 displayed significantly enhanced expression of all osteogenic proteins. Since all novel calcium phosphates supported cellular proliferation together with expression of bone-related proteins at least as much as TCP, these ceramics can be regarded as potential bone substitutes. R1 and R1+SiO2 had the most effect on osteoblastic differentiation, thus suggesting that these materials may possess a higher potency to enhance osteogenesis than TCP.