Development of an Alginate-Based Microcarrier for the Expansion of Anchorage Dependent Cells

Background and Aim: Clinical implementation of regenerative medicinein the treatment of various diseases necessitates the developmentof the cell culture methods which provide sufficient cell number ofthe specified tissues. Microcarrier-Based cell culture overcomes thelimitations of the conventional 2D cultivation methods by supplying highsurface to volume ratio. Alginate hydrogels are great of an interest intissue engineering due to their advantages such as biocompatibility, nonetoxicity and mimicking several extracellular matrix characteristics. Wehypothesized that treatment of Ca-alginate hydrogels with either an ECMprotein or a polycation would promote cell attachment.Methods: The calcium-alginate microbeads were prepared by drippingsodium alginate solution into an aqueous solution of calcium chlorideunder high voltage electrostatic field. Gelatin and chitosan solution ofdifferent concentrations were applied for the surface treatment of thehydrogels. Chitosan was coated on the hydrogel surfaces by two differentmethods. In the first method, the hydrogels were immersed into thechitosan solution under gentle agitation, while in the second strategyalginate solution directly dropped into the chitosan solution containingcalcium chloride. Gelatin coated alginate microbeads were prepared viaincubation of hydrogels in gelatin solution under continuous agitation at37˚C. To promote covalent crosslinking of gelatin, the beads were furthercrosslinked by glutaraldehyde. The mouse preosteoblast (MC3T3-E1) cellline was cultured on the modified microbeads in stationary as the modelsystem and its proliferation was assessed by MTT method.Results: MC3T3-E1 cells attached and expanded rapidly on the gelatincoatedhydrogels, whereas no significant cell growth was observed onthe chitosan coated ones at all tested concentrations. Glutaraldehydecrosslinking significantly improved the stabilization of the covalentgelatin as the cells could not attach and proliferate on the beads coatedwith gelatin solely. Among examined gelatin concentrations (1, 1.25 & 1.5% (w/v)), treatment of the microbeads with gelatin solution of 1.25%had the best results of the cell proliferation after 48 h.Conclusion: Our results demonstrated that gelatin coated Ca-alginatehydrogels can be applied as biocompatible microcarriers in tissueengineering applications. Moreover, it was revealed that chitosanwould not be an appropriate coating for microcarriers to promote cellattachment and proliferation.

Keywords:

Microcarrier , Ca-alginate , Tissue engineering , Gelatin , Chitosan