Studies on the synthesis and characterization of porous and dissolvable alginate microcarriers

Abstract

The demand for cell culture technologies dramatically increases to supply cells for various applications, such as cell-based therapy. Accordingly, microcarriers have gained great attention for the production of a large amount of cells with a bioreactor. In particular, a porous microcarrier presents unique benefits for cell culture, such as a large surface area, a high cell density, and good transports of nutrients and wastes to the growing cells. However, conventional porous microcarriers cause a difficulty in cell harvesting post cell culture because the conventional carriers are not dissolved in a simple and controllable way and thus additional treatment of digesting enzymes is required to detach the cells. In this study, a porous microcarrier was made of Arg-Gly-Asp (RGD) peptide grafted alginate, which was expected to be readily dissolved by EDTA treatment for easy and high-efficiency cell harvest. Agarose beads were produced and used as a porogen to make pores in RGD-alginate microcarriers. To examine the cell adhesion and growth depending on pore sizes, the different agarose beads were produced to have 5 ~ 30 μm and 30 ~ 60 μm. Alginate microcarriers containing the agarose beads were produced by using electrospray equipment at a flow rate of 10 mL/h to create a uniform microcarrier with a high yield. Microporous structures were successfully formed by the removal of the agarose beads by heating them at 65 ℃ for 24 h. The porosity and pore size of the resultant porous alginate microcarriers were examined by microscopy. Next, in vitro cell culture experiments were conducted to evaluate the ability of the porous alginate microcarriers to support cell adhesion and growth. The porous microcarrier did not significantly affect cell adhesion and growth. The cells on the porous microcarriers exhibited well-spread morphologies, indicating good cell-material interactions. Finally, simple and efficient cell harvesting from the porous alginate-based microcarriers were demonstrated by EDTA treatment in 1 minute. These porous and dissolvable microcarriers can be further employed for the expansion of various cells, such as mesenchymal stem cells, and cell delivery vehicles for tissue regeneration.