Dextran-based matrix functionalization to promote WJ-MSCs amplification: synthesis and characterization

Several clinical studies have reported the benefit of the administration of Mesenchymal Stem Cells (MSCs) in cell therapies. However, their routine applications need new substrates to amplify MSCs in vitro according to Good Manufacturing Practices (GMP) conditions and microcarriers are particularly suited for these purposes. In order to optimize the surface properties of Cytodex I microcarriers (Cyt), poly N-isopropylacrylamide (pNIPAM) has been grafted on their surface to promote MSCs adhesion, proliferation, but also to control their detachment by a decrease in temperature. The polymer coating generated on the microcarriers was analyzed using Time-of-Flight, Nanoscale Secondary Ion Mass Spectrometry, and Atomic Force Microscopy. We have confirmed the success of the pNIPAM grafting on Cyt with a two-steps reaction and correlated the influence on matrix functionalization in the function of the organic solvent used to disperse the microcarriers. The effects of pNIPAM functionalization have been explored on Wharton's jelly-MSCs (WJ-MSCs) culture and cell thermal detachment was monitored with fluorescent microscopy. The in vitro results have indicated that WJ-MSCs have a better growth on Cyt-pNIPAM. However, pNIPAM thermal cell detachment was lower than trypsinization, implying that the minimum effective molecular weight and surface density of polymer chains have still to be future optimized.