Guest-host supramolecular assembly of injectable hydrogel fibers for cell encapsulation

The fibrous architecture of the extracellular matrix (ECM) is recognized as an integral regulator of cell function. However, there is an unmet need to develop mechanically robust biomaterials mimicking nanofibrous tissue topography that are also injectable to enable minimally invasive delivery. In this study we have developed a fibrous hydrogel composed of supramolecularly-assembled hyaluronic acid (HA) nanofibers that exhibits mechanical integrity, shear-thinning, rapid self-healing, and cytocompatibility. HA was modified with methacrylates to permit fiber photocrosslinking following electrospinning and either ‘guest’ adamantane or ‘host’ β-cyclodextrin groups to guide supramolecular fibrous hydrogel assembly. Analysis of fibrous hydrogel rheological properties showed that the mixed guest-host fibrous hydrogel was more mechanically robust (6.6 ± 2.0 kPa, storage modulus (G′)) than unmixed guest hydrogel fibers (1.0 ± 0.1 kPa, G′) or host hydrogel fibers (1.1 ± 0.1 kPa, G′) separately. The reversible nature of the guest-host supramolecular interactions also allowed for shear-thinning and self-healing behavior as demonstrated by cyclic deformation testing. Human mesenchymal stromal cells (hMSCs) encapsulated in fibrous hydrogels demonstrated satisfactory viability following injection and after seven days of culture (> 85%). Encapsulated hMSCs were more spread and elongated when cultured in viscoelastic guest-host hydrogels compared to non-fibrous elastic controls, with hMSCs also showing significantly decreased circularity in fibrous guest-host hydrogels compared to non-fibrous guest-host hydrogels. Together, these data highlight the potential of this injectable fibrous hydrogel platform for cell and tissue engineering applications requiring minimally invasive delivery.