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Despite rigorous research, inferior mechanical properties and structural homogeneity are the main challenges constraining hydrogel's suturability to host tissue and limiting its clinical applications. To tackle those, we developed a reverse solvent interface trapping method, in which organized, graphene-coated microspherical cavities were introduced into a hydrogel to create heterogeneity and make it suturable. To generate those cavities, (i) graphite exfoliates to graphene sheets, which spread at the water/ heptane interfaces of the microemulsion, (ii) heptane fills the microspheres coated by graphene, and (iii) a cross-linkable hydrogel dissolved in water fills the voids. Cross-linking solidifies such microemulsion to a strong, suturable, permanent hybrid architecture, which has better mechanical properties, yet it is biocompatible and supports cell adhesion and proliferation. These properties along with the ease and biosafety of fabrication suggest the potential of this strategy to enhance tissue engineering outcomes by generating various suturable scaffolds for biomedical applications, such as donor cornea carriers for Boston keratoprosthesis (BK).

© 2019 Acta Materialia Inc. To address the shortcomings associated with corneal transplants, substantial efforts have been focused on developing new modalities such as xenotransplantion. Xenogeneic corneas are anatomically and biomechanically similar to the human cornea, yet their applications require prior decellularization to remove the antigenic components to avoid rejection. In the context of bringing decellularized corneas into clinical use, sterilization is a crucial step that determines the success of the transplantation. Well-standardized sterilization methods, such as gamma irradiation (GI), have been applied to decellularized porcine corneas (DPC) to avoid graft-associated infections in human recipients. However, little is known about the effect of GI on decellularized corneal xenografts. Here, we evaluated the radiation effect on the ultrastructure, optical, mechanical and biological properties of DPC. Transmission electron microscopy revealed that gamma irradiated decellularized porcine cornea (G-DPC) preserved its structural integrity. Moreover, the radiation did not reduce the optical properties of the tissue. Neither DPC nor G-DPC led to further activation of complement system compared to native porcine cornea when exposed to plasma. Although, DPC were mechanically comparable to the native tissue, GI increased the mechanical strength, tissue hydrophobicity and resistance to enzymatic degradation. Despite these changes, human corneal epithelial, stromal, endothelial and hybrid neuroblastoma cells grew and differentiated on DPC and G-DPC. Thus, GI may achieve effective tissue sterilization without affecting critical properties that are essential for corneal transplant survival.

Electron beam (E-beam) irradiation is an attractive and efficient method for sterilizing clinically implantable medical devices made of natural and/or synthetic materials such as poly(methyl methacrylate) (PMMA). As ionizing irradiation can affect the physicochemical properties of PMMA, understanding the consequences of E-beam sterilization on the intrinsic properties of PMMA is vital for clinical implementation. A detailed assessment of the chemical, optical, mechanical, morphological, and biological properties of medical-grade PMMA after E-beam sterilization at 25 and 50 kiloGray (kGy) is reported. Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry studies indicate that E-beam irradiation has minimal effect on the chemical properties of the PMMA at these doses. While 25 kGy irradiation does not alter the mechanical and optical properties of the PMMA, 50 kGy reduces the flexural strength and transparency by 10% and 2%, respectively. Atomic force microscopy demonstrates that E-beam irradiation reduces the surface roughness of PMMA in a dose dependent manner. Live-Dead, AlamarBlue, immunocytochemistry, and complement activation studies show that E-beam irradiation up to 50 kGy has no adverse effect on the biocompatibility of the PMMA. These findings suggest that E-beam irradiation at 25 kGy may be a safe and efficient alternative for PMMA sterilization.

© 2019 Acta Materialia Inc. To address the shortcomings associated with corneal transplants, substantial efforts have been focused on developing new modalities such as xenotransplantion. Xenogeneic corneas are anatomically and biomechanically similar to the human cornea, yet their applications require prior decellularization to remove the antigenic components to avoid rejection. In the context of bringing decellularized corneas into clinical use, sterilization is a crucial step that determines the success of the transplantation. Well-standardized sterilization methods, such as gamma irradiation (GI), have been applied to decellularized porcine corneas (DPC) to avoid graft-associated infections in human recipients. However, little is known about the effect of GI on decellularized corneal xenografts. Here, we evaluated the radiation effect on the ultrastructure, optical, mechanical and biological properties of DPC. Transmission electron microscopy revealed that gamma irradiated decellularized porcine cornea (G-DPC) preserved its structural integrity. Moreover, the radiation did not reduce the optical properties of the tissue. Neither DPC nor G-DPC led to further activation of complement system compared to native porcine cornea when exposed to plasma. Although, DPC were mechanically comparable to the native tissue, GI increased the mechanical strength, tissue hydrophobicity and resistance to enzymatic degradation. Despite these changes, human corneal epithelial, stromal, endothelial and hybrid neuroblastoma cells grew and differentiated on DPC and G-DPC. Thus, GI may achieve effective tissue sterilization without affecting critical properties that are essential for corneal transplant survival.

The repair of wounds through collective movement of epithelial cells is a fundamental process in multicellular organisms. In stratified epithelia such as the cornea and skin, healing occurs in three steps that include a latent, migratory, and reconstruction phases. Several simple and inexpensive assays have been developed to study the biology of cell migration in vitro. However, these assays are mostly based on monolayer systems that fail to reproduce the differentiation processes associated to multilayered systems. Here, we describe a straightforward in vitro wound assay to evaluate the healing and restoration of barrier function in stratified human corneal epithelial cells. In this assay, circular punch injuries lead to the collective migration of the epithelium as coherent sheets. The closure of the wound was associated with the restoration of the transcellular barrier and the re-establishment of apical intercellular junctions. Altogether, this new model of wound healing provides an important research tool to study the mechanisms leading to barrier function in stratified epithelia and may facilitate the development of future therapeutic applications.