Title
Enhanced Articular Cartilage by Human Mesenchymal Stem Cells in Enzymatically Mediated Transiently RGDS–Functionalized Collagen–Mimetic Hydrogels
Author
Paresh A. Parmar, Jean–Philippe St–Pierre, Lesley W. Chow, Christopher D. Spicer, Violet Stoichevska, Yong Y. Peng, Jerome A. Werkmeister, John A.M. Ramshaw, Molly M. Stevens
Year
2017
Journal
Acta Biomaterialia
Abstract
Recapitulation of the articular cartilage microenvironment for regenerative medicine applications faces significant challenges due to the complex and dynamic biochemical and biomechanical nature of native tissue. Towards the goal of biomaterial designs that enable the temporal presentation of bioactive sequences, recombinant bacterial collagens such as Streptococcal collagen–like 2 (Scl2) proteins can be employed to incorporate multiple specific bioactive and biodegradable peptide motifs into a single construct. Here, we first modified the backbone of Scl2 with glycosaminoglycan–binding peptides and cross–linked the modified Scl2 into hydrogels via matrix metalloproteinase 7 (MMP7)–cleavable or non–cleavable scrambled peptides. The cross–linkers were further functionalized with a tethered RGDS peptide creating a system whereby the release from an MMP7–cleavable hydrogel could be compared to a system where release is not possible. The release of the RGDS peptide from the degradable hydrogels led to significantly enhanced expression of collagen type II (3.9 fold increase), aggrecan (7.6 fold increase), and SOX9 (5.2 fold increase) by human mesenchymal stem cells (hMSCs) undergoing chondrogenesis, as well as greater extracellular matrix accumulation compared to non–degradable hydrogels (collagen type II; 3.2 fold increase, aggrecan; 4 fold increase, SOX9; 2.8 fold increase). Hydrogels containing a low concentration of the RGDS peptide displayed significantly decreased collagen type I and X gene expression profiles, suggesting a major advantage over either hydrogels functionalized with a higher RGDS peptide concentration, or non–degradable hydrogels, in promoting an articular cartilage phenotype. These highly versatile Scl2 hydrogels can be further manipulated to improve specific elements of the chondrogenic response by hMSCs, through the introduction of additional bioactive and/or biodegradable motifs. As such, these hydrogels have the possibility to be used for other applications in tissue engineering.
Instrument
J-715
Keywords
Circular dichroism, Secondary structure, Thermal stability, Biochemistry, Materials