Osteoblast response to commercially available demineralized bone matrices - An in-vitro study.

Objective: Reconstruction of lost attachment apparatus is a major goal of periodontal therapy. Although various osteoinductive bone replacement grafts (BRGs) have been used with apparent clinical success, unequivocal evidence of osteoinductivity may be obtained only through the demonstration of increased osteoblastic/osteoclastic differentiation following exposure to these materials. Materials and Methods: Bone marrow stem cells (BMSCs) obtained from rat femur were cultured in Dulbecco's Modified Eagles Medium (DMEM) and 10% fetal bovine serum (FBS). They were then exposed to two demineralized bone matrices (DBM's) - Grafton and Osseograft, and divided into three groups, comprising of a negative control (BMSC + DMEM + 10% FBS), Grafton, Osseograft. An osteogenic medium (OM) (10 hm dexamethasone, 10 hm b-glycerophosphate, and 50 μg/ml ascorbic acid) was added to create three subgroups comprising of a positive control (OM), Grafton with OM, Osseograft with OM. Results: After an initial phase (up to day 5), both Grafton and Osseograft induced an increased proliferative activity in the BMSCs, which reached a plateau after day 10. These grafts also induced increased alkaline phosphatase activity when compared to the control groups and to BMSCs with an OM. Conclusion: Both Osseograft and Grafton are capable of inducing osteoblastic proliferation and differentiation.

Osteoblast response (initial adhesion and alkaline phosphatase activity) following exposure to a barrier membrane/enamel matrix derivative combination.

BACKGROUND AND OBJECTIVE: The enamel matrix derivative (EMD) has been used in combination with barrier membranes to optimize regeneration in vertical osseous defects. However, the osteoblast response when exposed to the EMD/barrier membrane combination has not yet been evaluated. The osteoblast behavior when exposed to a combination of regenerative materials must be evaluated to fully understand their effect on bone regeneration. Therefore, the present study was undertaken to estimate the initial adhesion and alkaline phosphatase (ALP) activity of an osteoblast cell line (SaOS-2) when exposed to four commercially available resorbable membranes and determine if the addition of EMD had any modulatory effect on osteoblast behavior. MATERIALS AND METHODS: 5 x 104 SaOS-2 cells between passages 7-10 were cultured in two 24-well culture plates. Plate A was used for the adhesion assay and Plate B was used for the ALP assay. A MTT (3-[4, 5-dimethylthiazolyl-2]-2, 5-diphenyltetrazolium bromide) assay was done after 24 hours to determine the adhesion of the osteoblastic cells to four barrier membranes: 1) a non cross-linked porcine Type I and III collagen membrane (BG), 2) a weakly cross-linked Type I collagen membrane (HG), 3) a glutaraldehyde cross-linked bovine Type I collagen (BM), and 4) a resorbable polymer membrane (CP). Osteoblast differentiation was studied using an ALP assay with p-nitro phenyl phosphate as the substrate at 24 hours, 72 hours, and 1 week. A total of 50 microg/ml of EMD dissolved in 10 mM acetic acid was added into each well and the entire experimental protocol outlined above was repeated. RESULTS: The osteoblast adhesion to collagen barriers showed a statistically insignificant reduction following the addition of EMD. Adhesion to the polymer barrier, although significantly lower when compared with collagen barriers, was unaffected by the addition of EMD. ALP activity after 1 week among the various groups was as follows: EMD alone (75.59+/-2.5)>EMD/BG(64.78+/-3.04)>EMD/HG(55.40+/-3.89) approximately EMD/BM(54.75+/-4.17)>BG (51.32+/-2.76)>HG(49.92+/-2.4)>BM(48.14+/-1.4)>Control(46.29+/-1.39)>EMD/CP (37.46+/-3.54)>CP(32.12+/-1.49) CONCLUSION: There was no additive effect on osteoblast adhesion/ALP activity following exposure to an EMD/polymer combination. EMD/collagen positively influences osteoblast differentiation in a time dependent manner.