EVALUATION OF THE IN VITRO SECRETORY PROFILE OF MESENCHYMAL STEM CELLS IN CONTACT WITH A TITANIUM-HYDROXYAPATITE BIOMATERIAL.

The roles of mesenchymal stem cells (MSCs) in the processes of tissue regeneration and reparation were debated very much in the last period. The MSCs seems to sustain the tissue restoration by maintaining such environmental conditions which favor this process due to their ability to release cytokines and even growth factors. Starting from this data we developed an experimental protocol aiming to evaluate the changes of the MSCs secreted substances in to the culture media after in vitro interaction with a titanium-hydroxyapatite (HAP-Ti) biomaterial as well as a control biomaterial, anodized titanium (Ti-a). From each biomaterial were prepared squared 0.6 mm plates as well as an elution. The secretion of MSCs was evaluated either after direct contact either after elution addition in culture media. An immunoenzymatic assay (ELISA) was used for following cytokines and growth factors: tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), interleukin 12 (IL12), interleukin 4 (IL4), interleukin 10 (IL10), tumor growth factor beta (TGF-beta) and vascular endothelial growth factor (VEGF). According to the data obtained in our experiments, evaluation of secretory profile in MSCs in vitro into contact with the tested biomaterials indicated that cells releases into the culture medium higher concentrations of TNF alpha and IFN gamma, changes with no statistical significance except elution prepared from anodized titanium (Ti-a). The effect, even present is less extensive in the case of HAP-Ti, which demonstrates its better quality compared to the material used as a positive control. In addition, an increased release of interleukins with suppressor and anti-inflammatory effects (IL10, IL4) appears suggesting a possible better tissue integration of this material. The in vitro MSCs contact with tested biomaterials appear to stimulate the release into the environment of VEGF, the highest concentration being found in tests with elution of HAP-Ti. Overall, our results suggested that the proposed materials are not very well structured and need to be optimized in order to be more stable. However it appears that HAP-Ti is less reactive than Ti-a suggesting that HAP-Ti should be the chosen material for future improvements. [ABSTRACT FROM AUTHOR]