Lowering of blood glucose to nondiabetic levels in a hyperglycemic pig by allografting of fetal pig isletlike cell clusters

BACKGROUND

Fetal pig isletlike cell clusters (ICCs) will differentiate when grafted into the thymus gland of outbred immunosuppressed nondiabetic pigs for up to 3 months. Whether these cells will survive for a similar period in a diabetic recipient and will mature with secretion of insulin to ameliorate the hyperglycemia is unknown.

METHODS

Between 40,000 and 125,000 ICCs (7,000 to 11,400 ICCs/kg) were injected into the thymus gland of five juvenile pigs immunosuppressed with cyclosporine and deoxyspergualin, and the animals were subsequently made diabetic by the injection of streptozotocin. Insulin was administered subcutaneously, with one pig dying from hypoglycemia. The animal with the least number of ICCs transplanted was killed 81 days later, and the graft was analyzed histologically. Blood glucose levels and porcine C-peptide in the remaining animals were monitored for a median of 101 days.

RESULTS

Histological analysis of the graft showed numerous epithelial cell clusters; the percentage of cells that contained insulin, glucagon, somatostatin, and pancreatic polypeptide were 61%, 64%, 25%, and 18%, respectively. Some cells contained more than one hormone. Porcine C-peptide was detected from 21 days after induction of diabetes but not before. In the pig receiving the most ICCs, blood glucose levels were lowered to nondiabetic levels 109 days after transplantation. Plasma C-peptide levels in response to glucagon in this pig steadily increased after grafting; peak levels were 0, 0.21, 0.45, and 0.52 ng/ml at 4, 21, 49, and 80 days after induction of diabetes compared to 0.09 ng/ml in control diabetic pigs. The secretion of C-peptide in response to oral and intravenous glucose and arginine also was greater than in untransplanted diabetic pigs, the pattern of secretion being consistent with developing fetal beta cells as the source of the C-peptide. Pancreatic insulin content was 0.1 mU/mg, 4% of that in nondiabetic pigs, and the number of beta cells per islet was 3 to 6 compared to 90 in nondiabetic controls.

CONCLUSIONS

ICCs will differentiate and function for up to 111 days when transplanted into outbred immunosuppressed pigs rendered diabetic. Blood glucose levels can be lowered to nondiabetic levels when sufficient numbers of ICCs are grafted.

Alcohol and the pancreas

This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The presentations were (1) Phenotypic alteration of myofibroblast during ethanol-induced pancreatic injury: its relation to bFGF, by Masahiko Nakamura, Kanji Tsuchimoto, and Hiromasa Ishii; (2) Activation of pancreatic stellate cells in pancreatic fibrosis, by Paul S. Haber, Gregory W. Keogh, Minoti V. Apte, Corey S. Moran, Nancy L. Stewart, Darrell H.G. Crawford, Romano C. Pirola, Geoffrey W. McCaughan, Grant A. Ramm, and Jeremy S. Wilson; (3) Pancreatic blood flow and pancreatic enzyme secretion on acute ethanol infusion in anesthetized RAT, by H. Nishino, M. Kohno, R. Aizawa, and N. Tajima; (4) Genotype difference of alcohol-metabolizing enzymes in relation to chronic alcoholic pancreatitis between the alcoholic in the National Institute on Alcoholism and patients in other general hospitals in Japan, by K. Maruyama, H. Takahashi, S. Matsushita, K. Okuyama, A. Yokoyama, Y. Nakamura, K. Shirakura, and H. Ishii; and (5) Alcohol consumption and incidence of type 2 diabetes, by Katherine M. Conigrave, B. Frank Hu, Carlos A. Camargo Jr, Meir J. Stampfer, Walter C. Willett, and Eric B. Rimm.

Chronic pancreatitis: complications and management

Chronic pancreatitis is characterized by progressive and irreversible loss of pancreatic exocrine and endocrine function. In the majority of cases, particularly in Western populations, the disease is associated with alcohol abuse. The major complications of chronic pancreatitis include abdominal pain, malabsorption, and diabetes. Of these, pain is the most difficult to treat and is therefore the most frustrating symptom for both the patient and the physician. While analgesics form the cornerstone of pain therapy, a number of other treatment modalities (inhibition of pancreatic secretion, antioxidants, and surgery) have also been described. Unfortunately, the efficacy of these modalities is difficult to assess, principally because of the lack of properly controlled clinical trials. Replacement of pancreatic enzymes (particularly lipase) in the gut is the mainstay of treatment for malabsorption; the recent discovery of a bacterial lipase (with high lipolytic activity and resistance to degradation in gastric and duodenal juice) represents an important advance that may significantly increase the efficacy of enzyme replacement therapy by replacing the easily degradable porcine lipase found in existing enzyme preparations. Diabetes secondary to chronic pancreatitis is difficult to control and its course is often complicated by hypoglycaemic attacks. Therefore, it is essential that caution is exercised when treating this condition with insulin. This paper reviews recent research and prevailing concepts regarding the three major complications of chronic pancreatitis noted above. A comprehensive discussion of current opinion on clinical issues relating to the other known complications of chronic pancreatitis such as pseudocysts, venous thromboses, biliary and duodenal obstruction, biliary cirrhosis, and pancreatic cancer is also presented.

Differentiation of fetal pig endocrine cells after allografting into the thymus gland

BACKGROUND

The thymus of large animals, such as the pig, is thought to be an appropriate site for transplanting adult islets, which contain numerous beta cells, for the purpose of reversing diabetes. Whether fetal islet-like cell clusters (ICCs), which contain few beta cells, will develop at this site, so that adequate amounts of insulin can be produced, is unknown.

METHODS

Between 15,000 and 40,000 ICCs were injected into the thymus gland of six juvenile immunosuppressed pigs, and the animals were killed up to 30 days later. The graft was then examined histologically and comparisons made with untransplanted ICCs and those grafted into the omentum of immunosuppressed pigs.

RESULTS

At transplantation, the percentage of cells in the ICCs containing insulin, glucagon, somatostatin, or pancreatic polypeptide was 9+/-1%, 13+/-2%, 9+/-1%, and 3+/-1% respectively. Within 9-30 days of transplantation into the thymus, the percentage of all endocrine cells increased, insulin to 41+/-3%, glucagon to 43+/-6%, somatostatin to 26+/-4%, and pancreatic polypeptide to 9+/-3%. There was co-localization of more than one hormone in some cells. Omental grafts contained a similar percentage of insulin and glucagon-containing cells, but significantly fewer somatostatin and pancreatic polypeptide-containing cells.

CONCLUSIONS

Endocrine cells from the fetal pig pancreas will differentiate when transplanted into the thymus gland of the pig, making this a suitable site for grafting ICCs to test their ability to normalize blood glucose levels of diabetic recipients.