Effects of dextran on proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells

Abstract

Bioreactors have been used extensively to construct tissue-engineered bone. However, mass transport and flow shear stress, the two main factors contributing to the construction of tissue-engineered bone, cannot be studied separately when changing the perfusing rate. A tackifier needs to be added into the medium to separate the two factors. This study investigated the feasibility of using dextran as a tackifier in the study of individual effects of mass transport and flow shear stress on the construction of tissue-engineered bone. Human bone marrow-derived mesenchymal stromal cells (hBMSC) were isolated and cultured in media containing 1%, 3%, 5%, 7% and 9% dextran [molecular weight (MW) 70000]. Cell proliferation and osteogenic differentiation were observed in vitro. hBMSC cultured without dextran provided a control group. Cell proliferation was found to have no significant statistical difference (P>0.05) with a dextran concentration range of 1-7%. No significant difference in alkaline phosphatase (ALP) activity (P>0.05) was found among the different groups. Alizarin red staining showed no difference in mineralized extracellular matrix among the groups with a concentration of dextran less than 9%. Expression of collagen, ALP, osteopontin (OPN) and osteocalcin (OC) genes did not show any difference with a concentration range of 1-7%. When using a bioreactor to construct tissue-engineered bone, it is feasible to add a 1-7% dextran (MW 70000) concentration into the medium in order to study the effects of mass transport and flow shear stress.