Tuning of cell proliferation on tough gels by critical charge effect

Abstract

Tough triple network (TN) hydrogels that facilitate cell spreading and proliferation and, at the same time, preserve high mechanical strength are synthesized by the introduction of a proper component of negatively charged moiety, poly(2-acrylamido-2-methyl-propane sulfonic acid sodium salt) (PNaAMPS), on which cells proliferate, with neutral moiety, poly(N,N-dimethylacrylamide) (DMAAm), on which cells do not proliferate, as the third network component, to PNaAMPS/PDMAAm double network (DN) gels. For synthesizing the tough TN gels to support cell viability, the effect of charge density on the behaviors of three kinds of cells, bovine fetal aorta endothelial cells (BFAECs), human umbilical endothelial cells (HUVECs), and rabbit synovial tissue-derived fibroblast cells (RSTFCs) were systematically investigated on poly(NaAMPS-co-DMAAm) gels with different charge density. The charge density of the gels was tuned by changing the molar fraction (F) of negatively charged monomer in the copolymer hydrogels. Critical F, which corresponds to a critical value of the zeta potential (zeta), is observed for cell spreading and proliferation. The critical F for BFAECs and HUVECs proliferate to confluent is F = 0.4 (zeta = -20 mV), whereas the critical F for RSTFCs shifts to F = 0.7 (zeta = -28.5 mV). The effect of gel charge density on cell behavior is correlated well with the total adsorbed proteins and fibronectin. By applying these results, cell proliferation is successfully realized on the tough TN hydrogels without surface modification with any cell adhesive proteins or peptides. The results will substantially promote the application of tough hydrogels as soft and wet tissues.

In vitro differentiation of chondrogenic ATDC5 cells is enhanced by culturing on synthetic hydrogels with various charge densities

“…This result is consistent with a previous study using endothelial cells on copolymer gels consist of dimethylacrylamide and sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (NaAMPS), P(NaAMPS-co-DMAAm) [14,15]. Electrostatic interaction between cells and negatively charged gels cannot explain the adhesion force between cells and the gels because the cell surface is also negatively charged.…”

“…It has been reported that negatively charged polyelectroryte gels have potential in cell scaffolds [11], drug delivery system [12], and microfluidic system [13]. We have found that endothelial cells can spread, proliferate, and reach confluence on synthetic negative charged hydrogels without modification of adhesive proteins, and adhesion, attachment and proliferation of the cells depends strongly on the charge density [11,14,15]. This result shows that negative charged hydrogels have potential in using as blood vessel.…”

“…Electrostatic interaction between cells and negatively charged gels cannot explain the adhesion force between cells and the gels because the cell surface is also negatively charged. We previously reported that when Zeta potential of the gel was higher than -20 mV (molar ratio of NaAMPS F<0.4), the concentration of adhesion proteins such as fibronectin adsorbed on the gels was low and cell density was also low, whereas when Zeta potential of the gel was decreased to -20 mV (molar ratio of NaAMPS F= 0.4) the concentration of the proteins adsorbed on the gels began to dramatically increase and the cell density also increased [14]. Similarly, our present result showed that attachment and spreading of ATDC5 cells on the gels had very low degree at molar fraction of AMPS, F=0.25, began to dramatically increase at F = 0.5 ( Figure 1).…”

“…We have reported that cell adhesion, attachment and proliferation are strongly dependent on charge density of polymer gels [11,14,15]. In this study, we investigated cell proliferation of ATDC5 cells on polymer gels with different charge density.…”

Adhesion, Spreading, and Proliferation of Endothelial Cells on Charged Hydrogels

“…Three kinds of cells, i.e., BFAECs, human umbilical vein endothelial cells (HUVECs), and rabbit synovial tissue-derived fibroblast cells (RSTFCs), on poly(NaAMPS-co-DMAAm) hydrogels with various charge density were investigated [21].…”