Cellular Changes of Stem Cells in Three Dimensional Culture

Abstract Purpose During various surgeries and procedures, such as distraction osteogenesis (DO) and orthodontics, skeletal tissues use mechanotransduction. Mechanotransduction is important for maintaining bone health and converting mechanical forces into biochemical signals. We hypothesized that cells put under mechanical stress would adapt and change morphologically and respond with a decrease in cellular proliferation in order to accommodate the stress differences. These differences will be measured on the molecular and genetic level. We also wanted to test the practicality of an in-vitro three dimensional gel model system. Methods We implemented a three dimensional cell culture model. The sample was composed of isolated mouse mesenchymal prefibroblast bone marrow cells from the femurs and tibias of 6-8 week-old wild type C57BL6 mice. The cells were seeded on fibronectin-coated hydrogels along with fibrin & nodulin growth factors. The variables tested were a no-force (control) and a force model. The force model required two 0.1 mm suture pins put through one 0.25 cm length of cell/gel matrix. After the experiments were run to completion, the samples were fixed with 4% paraformaldehyde and embedded in paraffin. Serial sections were cut at a thickness of 5 μm along the long axis for the force construct and encompassing the entire circular area of the control construct. Descriptive and bivariate statistics were computed, and the P value was set at 5%. Results There was a statistically significant difference between the two models. The force model had longer and straighter primary cilia, less apoptosis and an increase in cell proliferation. Also the shape of the cells was markedly different after the experiment. Conclusion The results of the study suggest cells put under tensile stress have the ability to mechanically sense the environment to provide improved adaptation. Our work also confirmed the usefulness of the in-vitro three dimensional gel model system to mimic in-vivo applications.