Osteoporosis is an immense and growing health and economic burden of the aging population. Its prevalence in both men and women makes it an important target for biochemical research and development. A comparative study of the skeletal gene expression in native trabecular bone and cartilage tissues to marrow mesenchymal stem cells (MSCs) was carried out on tissues and cells obtained from acetabular reaming from total hip replacement patients (n=10). The intent of these comparisons was to examine the differentiation potential of MSCs grown from the bone marrow that was cultured for 21 days in three types of media: control media supplemented with fetal bovine serum with (CM) and without dexamethasone (CM-D), and an artificial (AFM) devoid of any animal product supplementation. RNA was extracted from these samples, and the bone and cartilage, and qRT-PCR was carried out to measure the expression of five genes of interest. The genes of interest (COL1A1, RUNX2, SP7, DMP1, and SOST) were chosen to respectively assess the progression of cellular and tissue differentiation from MSCs into osteocytes.
There were significant differences in gene expression of RUNX2, SP7, DMP1, and SOST between CM, AFM, and bone samples suggesting that each of the culture conditions promoted differing amounts of osteogenic differentiation. CM samples were relatively undifferentiated compared to the CM-D and AFM cultured cells, and likely contained little or no osteocytes but likely had some amount of osteoblasts. AFM cells appeared to be the most differentiated based on comparisons of their expression of mRNAs found in osteocytes. Bone and cartilage samples were also tested for the same genes of interest. AFM, CM, and CM-D had higher gene expression in markers for osteoblasts that are in the process of differentiating, while bone and cartilage showed a higher expression of the terminal osteocytic marker. Overall, this study showed that artificial media cultured MSCs differentiate at a faster rate than cells grown in the animal supplemented media.