Expansion and Osteogenic Differentiation of BM MSCs in Different Concentrations of Fibronectin within Sodium Alginate Microcapsules

Abstract

Extracellular matrix plays an essential role in physiological and biological functions of cells. Sodium alginate microcapsule(SA-microcapsules) as three-dimensional culture medium simulates the normal tissue in a laboratory environment, which can be taken advantage for cell function assay in an extracellular matrix. Insoluble fibronectin is an extracellular matrix protein increasing the proliferation, differentiation, and migration of mesenchymal stem cells (MSC) as well as inhibiting their apoptosis; however, there is limited information on the effects of various concentrations of fibronectin on MSCs function. It is hoped to take a major step forward for optimization of MSCs proliferation and osteogenic differentiation in vitro in order to treat bone-related diseases through enhancing the synergistic effect of fibronectin on the function of BM MSCs. Materials and Methods: In this experimental study, using a gel injection device, BM-MSCs were encapsulated in sodium alginate microcapsules containing 1.25% alginate, 1% gelatin, and four different concentrations of fibronectin (0.01, 0.05, 0.1, and 0.2 mM). To investigate proliferation and apoptosis, microcapsules having BM-MSC were cultured in DMEM and hydrogen peroxide-containing DMEM, respectively. MTT assay was used to examine the proliferation of bone marrow mesenchymal stem cells 5, 10, 15, and 21 days after culture as well as 24 hours later to analyze apoptosis. Alkaline phosphatase and Alizarin red tests were conducted to assess osteogenic differentiation 21 days after culture of BM-MSC containing microcapsules in differentiation-inducing culture medium. result: At constant cell density and matrix elastity , increasing concentrations of fibronectin from 0.01 to 0.1 mM caused a significant increase in proliferation and differentiation and reduced apoptosis of BM MSCs. However, increasing concentration up to 0.2 mM led to a significant decrease in osteogenic proliferation and differentiation and increased apoptosis of bone marrow mesenchymal stem cells.