Effect of human serum on the differentiation of SAOS2 cells

There is evidence to support the view that osteoporosis contributes to the bone loss and tooth loss seen in periodontal disease. In a sister presentation to this meeting we have demonstrated that human serum from adult females, and post-menopausal serum in particular, induces the adipocyte differentiation of human osteoprogenitor cells. Therefore, factors exist in human adult female serum that may inhibit new bone formation, and, consequently, have a negative impact on the maintenance of bone volume. The study presented here was performed to analyse further, the effects of human serum on osteoprogenitor cell differentiation. OBJECTIVES: To determine whether human male serum induces adipocyte differentiation of osteoprogenitor cells. METHODS: The human osteosarcoma cell line, SAOS2, capable of both adipocytic and osteoblastic differentiation, was grown in medium containing either 10% foetal bovine serum (FBS), 10% rabbit serum (RS - a known inducer of bone marrow cell adipocytogenesis), or 10% pooled human male AB serum (HS). After 14 days, cells were fixed and stained for lipids with Oil-Red-O, or for calcified nodule formation with Alizarin Red in replicate plates. RESULTS: There was no significant change to the number of calcified nodules formed by SAOS2 cells due to culturing in the different serums. RS induced a highly significant increase (p<0.01) in adipocytogenesis of SAOS2 cells compared to FBS or to HS. No significant increase in adipocytogenesis was seen when SAOS2 cells were incubated with HS, compared to FBS. CONCLUSIONS: As expected, the rabbit serum had a highly significant adipogenic effect on SAOS2 cells. However, unlike serum derived from post- menopausal women as disclosed in the aforementioned sister presentation to this meeting, human male serum does not induce significant adipocytogenesis of osteoprogenitor cells over and above that of foetal bovine serum.