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Amelia L. Zellander, Mohsen Makhsous, Michael Cho; Poly(ethylene glycol diacrylate) - Poly(2-hydroxyethyl methacrylate) (PEGDA-PHEMA) Based Keratoprosthesis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6063.
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Adequate host integration and implant stability are imperative for achieving long term keratoprosthesis survival in patients. A hybrid implant that consists of porous PEGDA-PHEMA infused with collagen may support cornea tissue development. This construct can potentially serve as the skirt in a core-skirt keratoprosthesis model. To assess the hybrid implant’s suitability for tissue engineering applications, cell migration, extracellular matrix (ECM) production, and mechanical properties of porous PEGDA-PHEMA were evaluated.
Hybrid implants were placed on top of a layer of human corneal fibroblasts. Cells were allowed to migrate into the hybrid implant over a period of 2 weeks. DNA content was measured, and collagen gene expression was quantified. Mechanical properties of the hydrated porous PEGDA-PHEMA construct were determined. The implant’s pores were generated using two porogens: water or a 150% w/v sucrose solution.
Water porogen generated structures with 10 -30 μm diameter pores. In contrast, sucrose porogen produced a more heterogeneous pore distribution of 5 -100 μm diameter. However, no significant difference in the mechanical properties was observed. Elastic moduli for the porous PEGDA-PHEMA made with water or sucrose porogen were 274 ± 56 and 283 ± 45 kPa (p > 0.88) respectively, and the yield point 39.9 ± 17.7 and 28.7 ± 14.8 kPa (p > 0.59) respectively. DNA quantification showed that cells migrated into the hybrid implants by day 7; the number of migrated cells remained fairly constant up to day 13. The hybrid implant created with water porogen exhibited a higher collagen gene expression level as compared to the implant made with sucrose porogen.
A hybrid implant composed of PEGDA-PHEMA and collagen type I has potential applications for artificial cornea. Our results show that the hybrid implant promotes human corneal fibroblast migration and subsequently collagen type I gene expression. Because collagen type I is a major ECM component in the cornea, collagen secretion is important for tissue development. Results from mechanical testing demonstrate that the hybrid implants are structurally stable enough to resist rupture during in vitro experiments and potentially during in vivo implantation.
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