Adult Porcine Islet Isolation Using a Ductal Preservation Method and Purification With a Density Gradient Composed of Histidine-Tryptophan-Ketoglutarate Solution and Iodixanol

Background. Given the fragility of adult porcine islets, reduction of shearing stress in islet purification using histidine-tryptophan-ketoglutarate (HTK) solution and iodixanol could be an effective strategy. We examined the effect of ductal preservation with HTK solution and an islet purification protocol that utilizes HTK solution and iodixanol in adult porcine islet isolation. Methods. Islets were isolated with a modified Ricordi method using adult Prestige World Genetics (PWG) and Yucatan pigs. The discontinuous density gradient was composed of either HTK solution/iodixanol (n = 23, iodixanol group) or Hank's balanced salt solution (HBSS)/Ficoll (n = 17, Ficoll group). In the iodixanol group, ductal injection of HTK solution was performed before purification. Results. In PWG pigs, significantly higher islet yield after purification (3480 +/- 214.2 islet equivalent [IEQ]/g, P = .003) and higher recovery rate (85.45% +/- 3.49%, P = .0043) were obtained from the HTK/iodixanol group as compared to the HBSS/Ficoll group (1905 323.2 IEQ/g, and 67.22% +/- 4.77%, respectively). Similar results were obtained in Yucatan pigs with greater body weight. Conclusion. Ductal preservation and iodixanol-based islet purification using HTK solution improved the yield of adult porcine islet isolation compared to the conventional method using HBSS and Ficoll. The results of this study support the feasibility of an adult porcine islet isolation protocol using HTK solution and iodixanol, which have the favorable physical properties.