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Amelia Zellander, Richard Gemeinhart, Behrad Milani, Ali Djalilian, Mohsen Makhsous, Michael Cho; Designing a Novel Porous Keratoprosthesis to Promote Cornea Cell Ingrowth. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3479. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Limited donor cornea supplies and cornea transplant rejection necessitate the development of safe and effective keratoprostheses (KPros). This study evaluates cell growth into novel porous polymers that could be used in a corneal replacement device.
Porous Salt PHEMA-PMMA was composed of 10% v/v methyl methacrylate (MMA), 45% v/v 2-hydroxyethyl methacrylate (HEMA), and 0.07 M sodium chloride. Porous Gas Foamed PHEMA-PMMA was composed of 20% v/v MMA and 40% v/v HEMA. Prior to the introduction of human corneal fibroblasts (HCFs), polymer samples were coated with collagen type I. Cell proliferation and viability were assessed using AlamarBlue and Live Dead Cell Viability assays (Invitrogen), respectively. The structures of the porous PHEMA-PMMA samples were evaluated using scanning electron microscopy (SEM) and micro-computed tomography (μCT). Mechanical properties were evaluated in tension.
A high level of cell viability was observed on PHEMA-PMMA structures. Image projections created via confocal microscopy show that the depth of cell growth in Gas Foamed PHEMA-PMMA was greater than that observed on Salt PHEMA-PMMA. Day 7 image projections of Gas Foamed PHEMA-PMMA show viable cells at depths of approximately 100 µm below the surface on which cells were seeded. For Salt PHEMA-PMMA, the depth of cell growth is less pronounced at day 7; however, cell proliferation data confirms that Salt PHEMA-PMMA structures are cytocompatible. SEM and μCT data indicate that both structures have a high density of pores. Among the two structures, Gas Foamed PHEMA-PMMA appeared to have the higher pore interconnectivity. For Gas Foamed PHEMA-PMMA, elastic modulus (E) and ultimate tensile strength (UTS) are 4081 ± 808 kPa and 263 ± 66 kPa, respectively. For Salt PHEMA-PMMA, E and UTS are 678 ± 72 kPa and 125 ± 25 kPa, respectively.
Pore architecture, mechanical stability, and cytocompatibility are vital design parameters for KPros. Porous PHEMA-PMMA is cytocompatible. Increased pore interconnectivity appears to allow greater cell growth into the body of porous PHEMA-PMMA structures. The polymers appear to be strong enough to be sutured and to maintain their structures under ocular forces as host tissue integrates. KPros made with porous PHEMA-PMMA may provide additional options for patients for whom donor corneas are inappropriate or inaccessible.
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