Introduction: Mimicking the structures and functions of extracellular matrix (ECM) is always a important guidance for biomaterials design. ECM takes a key role in signal transduction[1]. For example, enzymes are secreted or locally activited by migrating cells to degrade, and then to remodel the ECM[2]. Therefore, a 3D matrix simulating the structure and function of ECM provides a better model system of physiological environment for cell migration study. Hyaluronic acid (HA) derivatives are widely used in biomedical applications such as drug delivery, wound healing and tissue engineering. The present study mainly focuses on the fabrication of an active and cell-responsive HA-based hydrogel. The migration behaviors of human vascular smooth muscle cells (SMCs) are studied in the 3D matrix.
Materials and Methods: HA was modified with methacrylic anhydride under ice bath to introduce the vinylidene groups. The obtained HA derivatives were used as the main structural component of the hydrogel and crosslinked by a peptide through micheal-addition. A peptide sequence (Ac-GCRD-GPQG-IWGQ-DRCG-NH2, MMP-SP) with two –SH groups and sensitive to matrix metalloproteinases (MMPs), a protease family extensively involved in tissue development and remodeling[3], was chosen as cell-responsive crosslinker. The mechanical properties of the hydrogel in water and PBS were characterized, and the degradation behavior in MMP-2 was studied.
Figure.1 Schematic illustration of fabrication of HA derivatives, formation of hydrogel, and cell migration of SMCs in 3D matrix.
Results and Discussion: Methacrylic anhydride molecules were successfully grafted onto the HA molecules, with a grafting ratio of 50%. The HA hydrogel crosslinked the MMP-sensitive peptide (MMP-SP) showed an obvious degradation tendency in the presence of MMP-2 with a wight loss of nearly 50% in 4 d, while the hydrogel crosslinked by MMP-insensitive dithiothreitol (DTT) showed no obvious weight loss. The hydrogels crosslinked by MMP-SP and DTT showed almost the same mechanical propeties, with a young’s modulus between 2-5 kPa. Cell migration behavior of SMCs in 3D hydrogels will be subsequently studied.
Conclusions: Vinylidene-modified HA derivatives were successfully synthesized. Hydrogels that were sensitive to MMPs were fabricated for subsequent cell migration study.
Natural Science Foundation of China (21434006 and 21374097)
References:
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[2] Chapman H A. Plasminogen activators, integrins, and the coordinated regulation of cell adhesion and migration [J]. Current Opinion in Cell Biology, 1997, 9(5): 714-24
[3] Sternlict M D. How matrix metalloproteinases regulate cell behavior [J]. Annual review of cell and developmental biology, 2001, 17(4): 463-516