José Américo Bonatti

Comparison between different biomaterial scaffolds for limbal-derived stem cells growth and enrichment.

Purpose/Aim: Corneal epithelial stem cells have been used for the treatment of total limbal deficiency with corneal conjunctivalization and decreased vision secondary to a variety of ocular surface diseases. We set to compare the ability of different extracellular components in promoting growth and migration of these cells. Materials and Methods: Growth parameters were evaluated, including cell migration and proliferation (by wound healing) and mRNA gene expression (by quantitative RT-PCR). Results: The growth of corneal epithelial cells plated onto different matrix has shown that all treatments were efficient in supporting exponential growth, with a small increase in the puramatrix and collagen I groups when compared with fibrin treatment, which displayed the best doubling time rate and saturation density. The mRNA relative levels for c-myc, a proliferation marker, were considerably higher in the fibrin-coated group. In a smaller extent, the same could be observed for the puramatrix and collagen I groups. The same pattern could be observed for β-1 and α-6-integrin mRNA relative levels. The levels of CD71 mRNA, a LESC negative marker, were decreased in all groups, with a greater decrease in the fibrin group. We also found that the relative mRNA levels of the efflux pump ABCG2 and ▵Np63 transcripts were significantly higher in the fibrin group but not for collagen and puramatrix groups. Moreover, a diminished capacity of wound repair was observed for the uncoated control while the coated biomaterial groups were able to restore the cell-covered surface at some extent. Conclusion: All components tested were effective in promoting growth of corneal epithelial cells and maintenance of stem cell putative markers when compared with the uncoated surface group. Fibrin was far superior than collagen I and puramatrix in promoting survival, growth and migration of these cells.

A fibrin-related line of research and theoretical possibilities for the use of fibrin glue as a temporary basal membrane in non-perforated corneal ulcers and in photorefractive keratectomy (PRK)-operated corneas

PURPOSE To report a specific line of research developed at the University of São Paulo/Brazil on fibrin glue used for sealing corneal perforations and the perspectives of use on non-perforated corneal ulcers and photorefractive keratectomy-operated corneas. METHODS To describe fibrin glue manufacture, development of a device to test the glued perforated corneal area resistance, subsequent experimental investigations of the use of the fibrin glue in corneal perforations, reporting its efficacy, mechanical resistance experiments and histological study. Finally, the medical literature basis is searched to propose studies on the use of fibrin as a temporary basal membrane on non-perforated corneal surfaces like non-infectious corneal ulcers and on post-photorefractive keratectomy corneal surfaces. RESULTS The development of fibrin glue, the device for resistance experiments, the efficacy, resistance and histological studies on fibrin glue used for sealing corneal perforations are reported as well as the scientific literature basis for the proposed studies on the use of fibrin as a temporary basal membrane on non-perforated corneas like non-perforated corneal ulcers and photorefractive keratectomy corneal surfaces. CONCLUSION A specific line of research was reported on fibrin glue to seal corneal perforations at the University of São Paulo/Brazil and the theoretical perspectives for the use of fibrin in non-perforated corneal ulcers and on photorefractive keratectomy-operated corneas in an attempt to reduce corneal haze.

Development of an aspheric 22-diopter 50-mm diameter magnifier

PURPOSE To develop in an interdisciplinary approach between ophthalmology and design areas an ergonomic +22-diopter 50-mm aspheric hand magnifier for low vision. METHODS An aluminum cylinder was cut, processed using a lathe and carved to produce a ring that accommodated a 50-mm aspheric lens, with an external depression not to slide from the holders fingers. A cylindrical steel bar was cut, processed using a lathe and carved in order to form an externally turned ring to be screwed into the internal thread of the aluminum ring, to maintain the lens in a steady position. Both rings were submitted to electrostatic painting with a dull black electrostatic Epoxi ink, except the lower border of the external ring, to indicate the correct side of the magnifier to face the material to be read. RESULTS A 22-diopter 50-mm diameter aspheric lens magnifier with a black ring to be hold at its external circular depression was obtained in order to safely search the adequate reading focus with an inferior aluminum colored ring to face the object to be read and allow a less distorted reading. This is the first Brazilian high-magnification great-diameter magnifier for low vision that permits basically the focusing on an entire word, not only syllables, in order to allow a faster and more comfortable reading. CONCLUSIONS By an interdisciplinary approach a 22-diopter 50-mm aspheric lens magnifier was developed with image and ergonomic characteristics such as to permit comfortable and adequate reading performance in cases of low vision.