UV photopolymerised biosynthetic PVA hydrogels with tailored permselectivity for cell immunoisolation

Abstract

Cell immunoisolation systems are fast becoming a favourable approach to cure various challenging diseases and disorders such as type I diabetes. Although the addition of biological molecules to cell immunoisolation devices can significantly enhance their performance by supporting cell viability and function, little is known about their effects on the immunoisolating membrane properties especially its permselectivity.

Therefore, this research focused on examining the effect of combining biological molecules with a synthetic polymer on the permeability of hydrogels, with a specific emphasis on encapsulation of insulin producing cells for treatment of diabetes. The research aimed at achieving an optimum balance between a controlled permselectivity and cell survival support. It was hypothesised that covalent incorporation of small amounts of model extracellular matrix (ECM) molecules, heparin and gelatin, would support cell viability without compromising the controlled permselectivity and physico-mechanical properties of the base PVA network.

Varying the number of functional groups per PVA backbone successfully controlled the PVA permeability and physico-mechanical properties. A suitable degree of permselectivity was achieved by the highly crosslinked hydrogels. Covalent incorporation of heparin and gelatin at low percentage was successfully achieved without interfering with either their biofunctionalities or the base PVA properties, including its permselectivity. Moreover, the incorporated ECM analogues supported the viability and metabolic activity of pancreatic β-cell lines encapsulated for two weeks. Consequently, biosynthetic hydrogels composed of permselective PVA base material and a small amount of biological molecules show promise as immunoisolating materials for cell-based therapy.