Investigation of change in İGF-i, İGFBP-3, İGFBP-4 and papp-a concentrations in different passages of mesenchymal stem cells and fibroblast cells cultures

Insulin-like growth factors (IGFs) are necessary for cellular growth and differentiation. Pregnancy–associated plasma protein A (PAPP-A) induces the activation of IGF-I by proteolytic degradation of IGF-I dependent insulin-like growth factor binding protein-4 (IGFBP-4). PAPP-A has also affinity to IGFBP-2 and IGFBP-5, but it does not have affinity against IGFBP-3. Mesenchymal stem cells (MSCs) which can differentiate to osteocytes, chondrocytes, fibroblasts and many different cell types, secrete IGFs, Transforming growth factor-β (TGF- β), Tumor necrosis factor- α (TNF- α), Vascular endothelial growth factor (VEGF), Interleukin-10 (IL-10), IL-6 like growth factors and cytokines in in-vitro conditions. Therefore, IGF-I and other factors that regulate the metabolism of IGF-I can be secreted from these cells and observed in serum free media. These media do not contain animal-derived serum components. However, supplementary components can be added to serum-free media to support the growth and development of cells. In our study, we aimed to investigate the presence of IGF-I, IGFBP-3, IGFBP-4 and PAPP-A in culture media of MSC and fibroblast cells (FC). The concentration of these analytes which were obtained from three successive passages of MSC and FC culture media, were measured by ELISA and chemiluminescence. Along with this information, we can suppose that IGF-I, IGFBP-3, IGFBP-4 and PAPP-A are secreted from MSCs and FCs. According to our results, PAPP-A and IGFBP-4 concentrations increased whereas IGF-I concentrations decreased in successive passages of MSCs and FCs culture media. Decreased concentrations of IGF-I in culture media may be associated with the increased levels of IGFBP-4 compared to PAPP-A levels. We could not determine the exact concentration of IGFBP-3 (with either ELISA or chemiluminescence) because it was outside the reading range. Our data indicated the importance of the effect of IGF-I, IGFBP-3, IGFBP-4 and PAPP-A concentrations on cell differentiation which should be considered in future in-vitro studies. Key Words: IGF-I, IGFBP-3, IGFBP-4, Mesenchymal stem cells, PAPP-A