Determination of the kinetics of permeation of dimethyl sulfoxide in isolated corneas |
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Authors: | D. B. Walcerz M. J. Taylor A. L. Busza |
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Affiliation: | (1) Department of Mechanical Engineering, Worcester Polytechnic Institute, 100 Institute Road, 01609-2280 Worcester, MA;(2) MRC Medical Cryobiology Group, University Department of Surgery, Cambridge, UK;(3) Department of Biophysics, Hunterian Institute, The Royal College of Surgeons of England, London, UK;(4) Neurosciences Research Center, Allegheny-Singer Research Institute, Medical College of Pennsylvania, Allegheny Campus, 15212-9989 Pittsburgh, PA |
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Abstract: | Corneal cryopreservation requires that endothelial cells remain viable and intercellular structure be preserved. High viability levels for cryopreserved endothelial cells have been achieved, but preserving intercellular structure, especially endothelial attachment to Descemet's membrane, has proved difficult. Cell detachment apparently is not caused by ice, suggesting osmotic or chemical mechanisms. Knowledge of the permeation kinetics of cryoprotectants (CPAs) into endothelial cells and stroma is essential for controlling osmotic and chemical activity and achieving adequate tissue permeation prior to cooling. Proton nuclear magnetic resonance (NMR) spectroscopy was used to assess the permeation of dimethyl sulfoxide (DMSO) into isolated rabbit corneas. Corneas with intact epithelia were exposed to isotonic medium or 2.0 mol/L DMSO for 60 min and subsequently transferred to 2.0 or 4.0 mol/L DMSO, respectively, at 22, 0, or −10°C. DMSO concentration in the cornea was measured vs time. The Kedem-Katchalsky model was fitted to the data. Hydraulic permeability (m3/N·s) is 7.1×10−13+216%-11% at 22°C, 8.2×10−13+235%−21% at 0°C, and 1.7×10−14+19% −16% at −10°C. The reflection coefficient is 1.0+2%−1% at 22°C and 0°C, and 0.9±5% at −10°C. Solute mobility (cm/s) is 5.9×10−6+6%–11% at 22°C, 3.1×10−6+12%−11% at 0°C, and 5.0×10−8 cm/s+59%−40% at −10°C. |
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Keywords: | Corneal permeability diffusion diffusion coefficient difusion modeling hydraulic permeability dimethyl sulfoxide Arrhenius function cryopreservation nuclear magnetic resonance |
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