Abstract
Purpose :
Crosslinked collagen gels are a promising biomaterial for the encapsulation and delivery of cells as in vivo scaffolds for cell growth. To more closely approximate native corneal extracellular matrix, which includes glycosaminoglycans (GAGs) like hyaluronic acid, we are developing a simultaneously formed, in situ-forming, fully interpenetrating polymer network (IPN) of crosslinked collagen (x-Col) and crosslinked hyaluronic acid (x-HA).
Methods :
Collagen type I conjugated with dibenzocycloocytyne (DBCO) and azide groups via reaction with N-hydroxysuccinimide (NHS) esters served as x-Col precursors. HA conjugated with thiols and methacrylates served as x-HA precursors. Bio-orthogonal copper-free click chemistry and thiol-ene chemistry were used to form x-Col and x-HA, respectively. To fabricate the IPNs, DBCO-collagen, azide-collagen, thiolated-HA, and methacrylated-HA were mixed and incubated at 37°C.
Mechanical properties were measured as a function of storage (G') and loss (G'') moduli to evaluate the relative stiffness of the gels. Transparency was measured as transmittance after gelation. Cytocompatibility was evaluated via assessment of cell morphology and live/dead assay of corneal fibroblasts encapsulated within the IPN.
Results :
Gelation of occurred upon mixing with G' exceeding G'', though G’ continued to increase over a 3-hour incubation time. The x-Col/x-HA IPN exhibited a G' that was greater than 2-fold higher than the x-Col and physical collagen gels alone.
Live/dead assay showed improved cell viability over the x-Col gels alone. The x-Col/x-HA IPN also demonstrated similar transparency to x-Col gels and greater transparency compared to physical collagen gels. X-Col/x-HA IPN and x-Col gels had a transmittance greater than 85% in the visible spectrum (380-700nm) while physical collagen gels exhibited a low of 28% at lower wavelengths and a high of 78% at higher wavelengths.
Conclusions :
We have observed that x-Col/x-HA IPNs form transparent gels that maintain viability of encapsulated cultured fibroblasts and have improved mechanical properties compared to x-Col gels and physical collagen gels alone. The results support the material’s potential as a biomimetic scaffold for regenerative medicine applications.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.