Copyright @ Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Safe Induction of Diabetes by High-Dose Streptozotocin in Pigs Hidetaka Hara, MD, PhD,* Yih Jyh Lin, MD,* Xiaocheng Zhu, MD,* Hao-Chih Tai, MD,* Stuart L. Houser, MD,þ and David K.C. Cooper, MD, PhD, FRCS* Objectives: Streptozotocin (STZ) has been widely used to induce diabetes in rodents and nonhuman primates, but it has been found difficult to achieve a completely diabetic state in pigs in the absence of detrimental side effects. As a result, pancreatectomy has been advocated in this species. We have investigated the effects of 2 dosages of STZ to safely induce diabetes in pigs. Methods: Three pigs received Zanosar STZ at 150 mg/kg (group 1). Four pigs received Zanosar STZ at 200 mg/kg (group 2). The levels of glucose, insulin, and C-peptide when (a) fasting, (b) 30 minutes after eating, and (c) during intravenous glucose tolerance tests (IVGTTs) were measured in all pigs for 4 weeks after STZ injection. To confirm how long the diabetic state can be maintained after induction with STZ, levels were measured for 20 weeks in group 2. Results: One to 4 weeks after STZ administration, in group 1 (150 mg/kg) pigs, insulin and C-peptide levels were detected up to 7 KIU/mL and 0.4 ng/mL, respectively, both when fasting and after a meal test or IVGTT, indicating that the pigs had failed to become fully diabetic. In group 2 (200 mg/kg) pigs, insulin and C-peptide levels were less than the 2 KIU/mL and 0.25 ng/mL respective detection levels and did not increase after a meal test or IVGTT. Group 2 remained completely diabetic for the entire 20-week period of follow-up, without STZ-related hepatic or renal dysfunction. Conclusions: High-dose (200 mg/kg) Zanosar STZ induces diabetes safely and completely in pigs without side effects. Pancreatectomy can, therefore, be avoided. Key Words: diabetes induction, porcine C-peptide, streptozotocin, pig Abbreviations: ALT - alanine aminotransferase, AST - aspartate aminotransferase, AUC - area under the curve, iv - intravenous, IVGTT - intravenous glucose tolerance test, STZ - streptozotocin, Tx - allotransplantation (Pancreas 2008;36:31Y38) C linical islet allotransplantation in type 1 diabetic patients has been successfully established. 1Y3 However, its suc- cess is limited for several reasons that are partly immunologic and partly nonimmunologic in nature. Preclinical studies of islet allotransplantation in large animals are still needed to investigate these problems and explore possible solutions. The pig is useful in many respects as a model for human physiology and pathophysiology because many organ systems of this species, as well as physiological and patho- physiological responses, resemble those of the human. 4Y6 A single case of spontaneous diabetes with islet degeneration and atrophy has been reported in the pig, and its etiology was proposed to be infection. 7 Because of the extreme rarity of spontaneous type 1Ylike diabetes in the pig, diabetes must be induced experimentally, either surgically or chemically. Pancreatectomy has been used as a method of inducing diabetes in pigs, and impairment of glucose tolerance has been shown to be related to the extent of the pancreatectomy. 8 Total pancreatectomy has been reported to result in severe hyperglycemia. 9Y12 Based on the invasive surgery necessary to perform pancreatectomy, this method should be considered only when other methods are not feasible. A major disadvantage of pancreatectomy is that it includes removal of both exocrine and endocrine (including > and C cells) tissue, which is not characteristic of diabetes in humans 13 ; furthermore, replacement of exocrine enzymes (eg, pancrea- tase) is required, increasing the difficulty of long-term management of the diabetic pig. Streptozotocin (STZ), derived from the bacteria Strep- tomyces achromogenes, has been widely used to induce diabetes in rodents and nonhuman primates. The compound is transported into the A cells by the glucose transporter 2 receptor. 14,15 Streptozotocin induces DNA strand breaks and subsequently activates repair mechanisms that result in a reduction in cellular nicotinamide adenine dinucleotide and subphysiological adenosine triphosphate levels, which leads to cell death. 16 Nephrotoxicity and hepatotoxicity are disadvantages of STZ. 17,18 One study reported that a dose of 150 mg/kg induced diabetes in pigs, but this was reversible within 2 weeks, whereas 200 mg/kg resulted in insulin-requiring diabetes. 19 Dufrane et al 17 recently failed to achieve diabetes with STZ at a dose of 150 mg/kg despite some hepatotoxicity and nephrotoxicity and recommended that pancreatectomy should be carried out in this species. Furthermore, there have been no reports on how long the diabetic state can be maintained after induction with STZ. Our study reports the use of Zanosar STZ (clinical-grade STZ) for the safe induction of diabetes. ORIGINAL ARTICLE Pancreas & Volume 36, Number 1, January 2008 31 Received for publication September 6, 2006; accepted June 18, 2007. From the *Department of Surgery, Thomas E. Starzl Transplantation Institute, and †Division of Immunogenetics, Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburgh, PA; and ‡Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA. Hidetaka Hara, MD, PhD, was a recipient of a grant from Uehara Memorial Foundation, Japan. This work was carried out with a grant from the American Diabetes Association (ADA 1-04-RA-15). Reprints: David K. C. Cooper, MD, PhD, FRCS, Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Starzl Biomedical Science Tower, W1540, 200 Lothrop St, Pittsburgh, PA 15261 (e-mail: cooperdk@upmc.edu). Copyright * 2007 by Lippincott Williams & Wilkins Mohamed Ezzelarab, MD,* A.N. Balamurugan, PhD,*Þ Rita Bottino, PhD,Þ