Impact of Growth Factors on the Proliferation of Ear Mesenchymal Stem Cells on Porous Microcarriers

Abstract

Mesenchymal stem cells (MSCs) are emerging as an efficient tool for tissue engineering. Nevertheless, due to inefficient protocols for cell recovery, extensive ex-vivo expansion is required. MSCs are primary mechano-sensitive and anchorage dependent cells. Thus, the design of supporting scaffolds and the interactions with their microenvironment appear to be crucial for their efficient propagation in a bioreactor setting. In this work, we show that porous gelatin microcarriers (MC) are an efficient scaffold for MSC expansion. These supports, which contain multiple RGD sequences, allow an accurate spreading of these cells and their propagation in an undifferentiated state is as efficient as on conventional plastic culture dishes. Regarding the microenvironment for optimal cell growth, we observed that among the various standard culture process parameters, growth factor content of the culture medium was directly correlated with the apparent growth rate. Thus, the design of an efficient MSC culture process will require a close monitoring of these molecules, given their association with the percentage of cells in the S-phase of the cell cycle. These two components appear to be complementary for an efficient propagation of ear-derived MSCs (E-MSCs). We further discuss how controlling the bioreactor culture parameters should allow the modulation of the secretory profile of MSCs, thus enabling the generation of adult stem cells for specific therapeutic uses.