Bioactive surfaces from seaweed-derived alginates for the cultivation of human stem cells

Nowadays, modern approaches in tissue engineering include the combination of therapeutic relevant cells with high quality, biocompatible biomaterials. The resulting cellularized scaffolds are of great interest for several pharmaceutical applications such as drug screening/discovery, disease modeling, and toxicity testing. In addition, the introduction of human-induced pluripotent stem cells (hiPSCs) further increased the importance and the potential of tissue engineering not only for the pharmaceutical industry, but also for future therapeutic applications. Artificial microenvironments of hiPSCs comprise combinations of adhesive proteins and are particularly influenced by mechanical properties of the growth surface. The increasing focus on mechanical properties and the ability to adjust them propose alginate hydrogels as suitable candidates for engineered scaffolds. Ultra-pure alginates, however, are bioinert and require modifications for bioactivation. In this study, we present two modifications of alginate hydrogels based on direct covalent coupling of collagen I and coupling of a special linker molecule with subsequent Matrigel coating. We were able to demonstrate the successful adhesion and proliferation of hiPSCs on these linker-modified alginates. The developed modifications are particularly applicable for planar as well as spherical hydrogel surfaces. In this context, a scalable adherent suspension culture on alginate microcarriers could be established. Our data further indicate that larger alginate microcarriers modified with collagen I is less susceptible for agglomeration compared to small microcarriers. The obtained results indicate these modifications as suitable for both adhesion and cultivation of human stem cells such as human mesenchymal stem cells or hiPSCs