Thiolated poly(2-hydroxyethyl methacrylate) hydrogels as a degradable biocompatible scaffold for tissue engineering

Highlights: • Degradable hydrogels based on poly(2-hydroxyethyl methacrylate) were prepared. • Degradability was achieved by cross-linking of waters soluble copolymer of PHEMA via disulfide bridges. • Solubility of copolymers was enhanced by copolymerization with 2-methacryloyloxyethyl phosphorylcholine. • In vivo controlled degradation was confirmed using subcutaneous implantation of hydrogels in rats. • Presence of RGDS peptide and laminin in hydrogels improved mesenchymal cell adhesion. Research of degradable hydrogel polymeric materials exhibiting high water content and mechanical properties resembling tissues is crucial not only in drug delivery systems but also in tissue engineering, medical devices, and biomedical-healthcare sensors. Therefore, we newly offer development of hydrogels based on poly(2-hydroxyethyl methacrylate-co-2-(acetylthio) ethyl methacrylate-co-2-methacryloyloxyethyl phosphorylcholine) [P(HEMA-ATEMA-MPC)] and optimization of their mechanical and in vitro and in vivo degradability. P(HEMA-ATEMA-MPC) hydrogels differed in chemical composition, degree of crosslinking, and starting molar mass of polymers (15, 19, and 30 kDa). Polymer precursors were synthesized by a reversible addition fragmentation chain transfer (RAFT) polymerization using 2-(acetylthio)ethyl methacrylate containing protected thiol groups, which enabled crosslinking and gel formation. Elastic modulus of hydrogels increased with the degree of crosslinking (Slaughter et al., 2009) [1]. In vitro and in vivo controlled degradation was confirmed using glutathione and subcutaneous implantation of hydrogels in rats, respectively. We proved that the hydrogels with higher degree of crosslinking retarded the degradation. Also, albumin, γ-globulin, and fibrinogen adsorption on P(HEMA-ATEMA-MPC) hydrogel surface was tested, to simulate adsorption in living organism. Rat mesenchymal stromal cell adhesion on hydrogels was improved by the presence of RGDS peptide and laminin on the hydrogels. We found that rat mesenchymal stromal cells proliferated better on laminin-coated hydrogels than on RGDS-modified ones.