Preparation And Characterization Of Alginate/PEG Semi-IPNs Microcarriers For Expansion Of Stem Cell

The typical W/O suspension system was used to form the alginate basedmicrosphere carriers in this paper. Alginate was selected as the matrix material ofcrosslinked system, in addition, polyethylene glycol (PEG) were introduced into thissystem to construct the semi-interpenetrating network structure (Semi-IPNs).Thealginate/PEG semi-IPNs microcarriers contained disulfide bonds within the structure,whose greatest characteristic was that disulfide bond cleavage can occur under theinfluence of a particular reducing agent. Microcarriers were characterized byinfrared spectroscopy (FT-IR), SEM, particle size distribution statistics. Comparedwith microcarriers not with PEG, the precise degradation behaviors control ofmicrocarriers herein prepared with semi-IPNS can be achieved. We achieved thecontrollability of the degradation characteristics and particle size of microcarriers byadjusting the molecular weight of PEG, the mass ratio of PEG and alginate and thetype of the reducing agent. We also studied the modification time of chitosan andother impacts on micro-swelling properties and degradation time.Chitosan and heparin here were chosen to improve the cytocompatibility andmechanical properties through adsorbing to the surface of microcarriers.Furthermore, fibronectin (FN) and basic fibroblast growth factor (bFGF) were alsoimmobilized onto the surface of microcarriers to facilitate human umbilical cordblood mesenchymal stem cells (hUCB MSCs) adhesion and proliferation.hUCB MSCs were cultured on the microcarriers prepared with differentcomponents. The cell morphology and proliferation conditions were studied here.Results showed that microcarriers prepared after modification can support celladhesion and proliferation. Stem cells proliferated well on microcarriers modifiedwith fibronectin indicating that the fibronectin can satisfactorily improve thebiocompatibility of microcarriers. However, stem cells did not change significantlyon microcarriers modified with the growth factor. Degradation experiments showthat L-cysteine has minimal damage to cells which were suitable to recover cells.Fibronectin modified microcarriers are good for cell expansion.