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Christina Kong, Shreya Condamoor, Kate Xie, Ross Sayadi, Brian Johnson, Alan Widgerow, Marjan Farid; The Use of Micronanobubbles to Improve the Viability of Donor Corneal Tissue. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3821.
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© ARVO (1962-2015); The Authors (2016-present)
Micronanobubbles (MNBs) are miniature gaseous voids that contain oxygen or other gases and are capable of increasing the oxygen tension in solution for prolonged periods of time due to their slow rising velocity, stability in solution, and gradual shrinkage. We tested the hypothesis that MNBs containing oxygen or air added to Optisol solution will prolong endothelial cell (EC) viability of donor corneal tissues.
Two trials were done where the experimental group of corneas (n=3) was stored in MNB + Optisol solution (MNBs contained: air/21% O2 in Trial 1; 100% O2 in Trial 2) and control groups were stored in standard Optisol (n=3). Samples were stored at 4°C and assessed for EC density at weeks 0, 1, 2, 3 and 4 for Trial 1. Cell assessments for Trial 2 were limited to weeks 0, 1, and 2 due to tissues becoming too edematous. On day 28, EC counts were determined via specular microscopy and samples were qualitatively assessed for cell loss using calcein AM (CAM) stain. Statistical analysis was done using the Student’s t-test and the p-value cutoff set at p < 0.05.
After 4 weeks in Trial 1, the average EC loss for the experimental group was 35.33% ± 24.075% and was 27.9% ± 20.379% for the control group with no significant difference between the groups (p=0.704). After 2 weeks in Trial 2, the average cell loss was 9.6% ± 1.12% in the experimental group and 1.73% ± 7.41% in the control group with no significant improvement in cell survival in corneas stored with MNBs (p=0.28).
Both trials show that MNBs exposed to ambient air (Trial 1) and 100% oxygen (Trial 2) had no significant effect on the EC density of corneas compared to samples stored in standard conditions (4°C, 14 days). Transplant tissues often become edematous because of inadequate oxygenation of the tissue (in vivo corneas require at least 20 mm Hg oxygen from the aqueous humor) and edema is often a limiting factor in corneal transplantation. MNBs filled with 100 O2 or air should increase pO2 in transplant solution, reducing edema of the corneal tissues; however, free radical production of the MNBs may have contributed to the increased EC loss. Future studies examining the effects of storage temperature and free radical production must be done to further elucidate the role of MNBs in corneal transplants.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
MNB generation using gear pump.
Endothelial counts in Trial 1 samples.
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