Synthetic poly(amino acid) hydrogels with incorporated cell-adhesion peptides for tissue engineering

Preparation of soft poly(amino acid) hydrogels containing biomimetic cell-adhesive peptides was investigated. Covalently crosslinked gels were formed by radical co-polymerization of methacryloylated macromonomer poly[N(5)-(2-hydroxyethyl)-L-glutamine-stat-L-alanine-stat-methacryloyllysine] with 2-hydroxyethyl methacrylate (HEMA) as minor co-monomer. Hydrogels carrying biomimetic peptides were prepared by using methacryloylated peptides, such as methacryloyl-GGGRGDSG-OH and methacryloyl-GGGYIGSR-OH, as additional monomers in the polymerization mixture. Mechanical stability and swelling in water of the hydrogels obtained for different solid:water and polypeptide:HEMA ratios were evaluated. The microporosity of gels (5-20 microm), dependent on the polyHEMA phase separation in water, was followed by low-vacuum SEM. The effect of biomimetic modification of hydrogels with RGDS and YIGSR peptides on the seeding efficiency of porcine mesenchymal stem cells (MSCs) was studied in vitro. While unmodified hydrogels showed very low cell adhesion, due to their highly hydrophilic nature, the incorporation of adhesive peptides significantly improved the adhesion and viability of seeded cells.