Water and Cryoprotectant Permeability Characteristics of Isolated Human and Canine Pancreatic Islets

Cell Transplantation

Article

Erik J. Woods¹  Jun Liu¹  John K. Critser¹  Jonathan R. T. Lakey²  Michael A. J. Zieger³ 

[1] Cryobiology Research Institute, Wells Center for Pediatric Research, Indiana University Medical Center, Indianapolis, IN;Department of Veterinary Clinical Sciences, and Hillenbrand Biomedical Engineering Center, Purdue University, West Lafayette, IN;Department of Veterinary Clinical Sciences, and Hillenbrand Biomedical Engineering Center, Purdue University, West Lafayette, IN;Comprehensive Tissue Centre, Department of Surgery, Laboratory Medicine and Pathology, University of Alberta, Alberta, Edmonton, Canada;Methodist Research Institute, Methodist Hospital of Indiana, Inc., Indianapolis, IN;

关键词: Cryopreservation;    Pancreatic islet;    Permeability characteristics;   

DOI  :  10.1177/096368979900800510

来源: Sage Journals

【 摘 要 】

Cryopreservation allows accumulation of the necessary islet transplantable mass as well as adequate time for tissue typing and infectious disease screening. Cryopreservation protocols may be optimized by modeling the osmotically induced volume excursions that occur during the addition and removal of cryoprotective agents (CPAs). To that end, three transport parameters were measured at 22°C in canine and human islets isolated by collagenase digestion and euroficoll purification: (i) the apparent hydraulic conductivity (Lp), (ii) the permeability coefficient of the CPA (Ps), and (iii) the associated reflection coefficient (σ). The parameters were determined by volumetric analysis of islets upon abrupt exposure to 1, 2, and 3 M dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol (GLY), and propylene glycol (PG). The parameters were calculated using the Kedem-Katchalsky theory to describe islet volume excursion kinetics (assuming islets to be single equivalent osmotic units with the same volume and surface area of the actual islet) and a three-parameter curve fit was performed using the Marquardt-Levenberg method. It was determined that the permeability characteristics of pancreatic islets are species specific, and based upon the measured parameters, the highest Ps values for canine islets were observed following exposure to 2 M EG, and the highest Ps values for human islets were observed following exposure to 2 M PG. The permeability parameters were analyzed adjusting for islet radius using ANCOVA procedures to acquire least square means. For canine islets exposed to 2 M EG these values were determined to be 0.936 μm/min/atm, 2.47 μm/s, and 0.90 (for Lp, Ps, and ϕ, respectively) and for human islets exposed to 2 M PG the values were determined to be 1.56 μm/min/atm, 3.48 μm/s, and 0.85 (for Lp, Ps, and σ, respectively). These parameters were used in a model to calculate osmotically induced islet volumetric response upon addition/dilution of the optimum CPAs, taking into consideration critical volume excursion limits at which irreversible damage occurs.

【 授权许可】

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