Enzymatically Cross-linked Hydrogels Based on Synthetic Poly(α-amino acid)s Functionalized with RGD Peptide for 3D Mesenchymal Stem Cell Culture

Injectable hydrogel scaffolds combined with stem cell therapy represent a promising approach for minimally invasive surgical tissue repair. In this study, we developed and characterized a fully synthetic, biodegradable poly(N-5-(2-hydroxyethyl)-L-glutamine)-based injectable hydrogel modified with integrin-binding arginine-glycine-aspartic acid (RGD) peptide (PHEG-Tyr-RGD). The biodegradable hydroxyphenyl polymer precursor derivative of PHEG-Tyr was enzymatically cross-linked to obtain injectable hydrogels with different physicochemical properties. The gelation time, gel yield, swelling behavior, and storage modulus of the PHEG-Tyr hydrogels were tuned by varying the concentrations of the PHEG-Tyr precursors and horseradish peroxidase as well as the n(H2O2)/n(Tyr) ratio. The mechanical properties and gelation time of the PHEG-Tyr hydrogel were optimized for the encapsulation of rat mesenchymal stem cells (rMSCs). We focused on the 2D and 3D spreading and viability of rMSCs within the PHEG-Tyr-RGD hydrogels with different physicochemical microenvironments in vitro. Encapsulation of rMSCs shows long-term survival and exhibits cell-matrix and cell-cell interactions reflective of both the RGD concentration and hydrogel stiffness. The presented biomaterial represents a suitable biological microenvironment to guide 3D spreading and may act as a promising 3D artificial extracellular matrix for stem cell therapy.

Automated summary

Injectable hydrogel scaffolds combined with stem cell therapy offer a promising approach for tissue repair. The developed synthetic hydrogel was modified with an integrin-binding peptide, showing long-term survival of encapsulated cells and providing a suitable microenvironment for stem cell therapy. The study highlights the importance of optimizing mechanical properties and gelation time for successful application in 3D cell culture.