This work reports the development of new alginate-based hydrogels mimicking key features of the natural extracellular matrix, namely cell adhesion and cell-mediated matrix degradation. This work is part of the PhD works of Keila Fonseca.
Keila B. Fonseca, Sílvia J. Bidarra, Maria J. Oliveira, Pedro L. Granja and Cristina C. Barrias. Acta Biomaterialia, 2011.
The development of sophisticated three-dimensional (3-D) cell culture microenvironments that recreate some of the complexity of the natural extracellular matrix (ECM) remains a challenging task. Here, the modification of alginate through partial crosslinking with a matrix metalloproteinase (MMP) cleavable peptide (proline-valine-glycine-leucine-isoleucine-glycine, PVGLIG) is described, and its use in the preparation of injectable, in situ crosslinkable hydrogel-like matrices is proposed. PVGLIG-grafted algi- nates were synthesized by carbodiimide chemistry and characterized. Their biological performance was evaluated by comparing the response of 3-D cultured mesenchymal stem cells (MSCs) to alginate hydrogels containing only cell-adhesion peptides (RGD-alginate) or both peptides (PVGLIG/RGD-algi- nate). After 1 week, cells remained essentially round within RGD-alginate, while they exhibited an elon- gated morphology within PVGLIG/RGD-alginate hydrogels, forming cellular networks. This suggests that cells were able to structurally reorganize the matrix, through enzymatic hydrolysis of PVGLIG residues, overcoming biophysical hydrogel resistance. As shown by gelatine-zymography, MSC presented higher activity of MMP-2 when cultured within alginate functionalized with MMP-sensitive peptide, suggesting that the cellâ€™s proteolytic phenotype was modulated by the matrix composition. Additionally, PVGLIG/ RGD-alginate hydrogels were clearly degraded in cell culture. Taken together, the results demonstrate that the co-incorporation of MMP-labile peptides in cell-adhesive RGD-alginate hydrogels improved their performance as ECM analogues, providing a more dynamic and physiological 3-D cellular microenvironment.