Synthesis of Reversibly Crosslinked Hydrogel for Cell Delivery

K. Smith (1,2,3), A. Fokina (1,2,3), A. Baker (1,2,3), T. Führmann (1,2,3), M.S. Shoichet (1,2,3)

1: Donnelly Centre for Cellular and Biomolecular Research

2: Department of Chemical Engineering and Applied Chemistry

3: Institute of Biomaterials and Biomedical Engineering

When neural stem cells are differentiated in vitro on 2-D surfaces to neurons, neuronal networks form which are damaged when cells are removed from the surface and injected in vivo. This results in substantial cell death which can cause host tissue damage when injected into brain tissue.1 To overcome this problem, we propose to design a reversibly crosslinked hydrogel that would first allow cell culture and then serve as the vehicle for cell transplantation. The physical hydrogel blend of hyaluronan (HA) and methylcellulose (MC), HAMC, has been used extensively for cell delivery because it enhances transplant cell survival and attenuates the inflammatory response.2 While HAMC is not sufficiently stable for long-term cell culture, we propose to chemically crosslink HA and MC with an enzyme-cleavable group, thereby allowing long-term cell culture. By specifically degrading the crosslinks, we will then regenerate the original HAMC hydrogel, thereby enabling cell transplantation without impacting the neuronal network that formed during in vitro differentiation. Towards this end, HA and MC have been chemically modified to enable crosslinking with an enzymatically-cleavable peptide sequence. The synthesis and the cytocompatibility have been advanced and will be described.

1. Payne, S. L. et al. Initial cell maturity changes following transplantation in a hyaluronan- based hydrogel and impacts therapeutic success in the stroke-injured rodent brain. Biomaterials 192, 309–322 (2018).
2. Ballios, B. G. et al. A hyaluronan-based injectable hydrogel improves the survival and integration of stem cell progeny following transplantation. Stem Cell Reports 4, 1031-1045 (2015).
We are grateful to NSERC (Discovery to MSS, CREATE in M3 to KS) and CIHR (Foundation to MSS) for funding.