Influence of Hydrogenated Calcium Phosphate Surface on Potential of Stromal Stem Cells in Situ

Abstract

We have applied novel technique for enhancing bone tissue formation on micro- and nanostructured calcium phosphate (CP) coatings. CP surfaces with “primitive” physical-chemical composition, which is not corresponding to last one in bone, have an active effect on functional properties of mesenchymal stromal cell pull (MSCP). The studied micro-CP coatings, characterized by marked roughness of surface had an osteoinductive potential up to 100 %. Relief of CP coatings from HAP nanoparticles (30–50 nm) does not practically differ from ones designed by use of HAP microparticles. Roughness of all CP nanocoatings had average Ra=5.13−6.43 µm and Rz=18.71−24.16 µm that was corresponded to CP microcoatings one. Probability of bone plate formation on CP nanostructured coatings was only 12.5 %. Hydrogenation of the CP surface layer increased its negative charge that was evaluated by means of photoelectron work function (ϕ) measurement. An increment of ϕ at the values of ≈0.1−1 eV was supplied. This had an effect on the directions of MSCP differentiation. For example, connective tissue growth was improved. For all this, probability of following ossification with growth of membrane reticulated bone was 20 %. Vice versa, decrease of ϕ led to primary formation of bone from bone marrow MSCP. Technique of intracellular RNA staining detected the actively synthesized osteoblasts and bone marrow stromal cells. The above evidences that hydrogenation of CP coatings could in situ effect MSCP differentiation in fibroblasts or osteoblasts associated with stromal cells of hemopoietic inducing microenvironment.