Fetal calf serum concentration and sex did not affect the differentiation of human primary osteoblasts, in contrast to dexamethasone

Isolating primary human pre-osteoblasts from bone tissue is essential for research on bone formation and remodeling. A detailed characterization of these isolated cells is essential to study morphological and phenotypic alterations of the cells during 2D cell culture. Our present study characterized the proliferation and differentiation behavior of cells isolated from femoral heads with regard to different fetal calf serum (FCS, 5 and 10%) and dexamethasone concentrations (0, 10, and 100 nM). Concurrently, sex-specific differences during cultivation under the different conditions were assessed. After four passages in a calcium-free basal medium supplemented with 10% FCS, 50 µg/ml ascorbic acid, 1 mM β-glycerophosphate, and 100 nM dexamethasone, cells isolated from cancellous bone of femoral heads differentiated into mature osteoblasts based on their gene expression profiles with low inter-individual variation. When altering the composition of the medium for dexamethasone and FCS, it became apparent that the addition of dexamethasone was essential for the osteogenic differentiation in the early passages. The concentration of 100 nM dexamethasone was the most effective dose in inducing biomineralization-associated alkaline phosphatase (ALPL) gene expression and alkaline phosphatase (ALP) activity as well as mineralization. Reducing the FCS concentration in the medium was of less consequence and only slightly reduced cell number and type I collagen secretion. However, the higher FCS concentration of 10% seemed to attenuate sex-dependent effects during in vitro cultivation.