Development and in vitro evaluation of photocurable GelMA/PEGDA hybrid hydrogel for corneal stromal cells delivery

Gelatin methacrylate (GelMA) was proved to be a promising bioink for corneal stromal cell delivery. However, GelMA has low mechanical properties which makes it difficult to be suturable and handled for clinical applicattion. In this study, three different ratios of 12.5 % GelMA and 10 % PEGDA were investigated for corneal stromal cells delivery. The mixture containing 75 % GelMA and 25 % PEGDA (75G25P) was found to have reasonable cell viability and suturing strength. Moreover, collagen nanofibers were incorporated into 75G25P hydrogel to improve the mechanical and biomimetic properties of the construct (75G25P-E). A hybrid structure was obtained by injecting the optimized bioink on the electrospun collagen mat and crosslinking the structure using visible light. Subsequently, gene and protein expressions of the corneal stromal cell were assessed in 75G25P hydrogel with and without collagen nanofibers. Spatial elongated corneal stromal cells were observed in 75G25P-E samples after 14 days. The gene expression of corneal stromal cell markers (lumican and keratan sulfate) and collagen type I was up-regulated within the cells encapsulated in the 75G25P-E hydrogels over time as compared to the cells encapsulated in 75G25P samples. Finally, immunohistochemical analysis indicated that collagen type I and lumican were expressed in corneal stromal cells after 28 days which implied that the proposed structure can be a promising equivalent for corneal stromal tissue.