David C. Wahoff

Evolution of kidney, pancreas, and islet transplantation for patients with diabetes at the University of Minnesota

Transplantation began at the University of Minnesota in 1963. Treatment of diabetes and its complications has been emphasized since 1966, when the first pancreas-kidney transplant was done. Of 3,640 kidneys transplanted by 1992, 1,373 were for diabetic recipients, including 658 from living donors and 715 from cadaver donors. The results progressively improved; since 1984, survival rates of kidney grafts have been similar for diabetic and nondiabetic recipients, with three fourths of the grafts functioning at 4 years. As of 1992, 501 pancreas transplants had been done, including 170 simultaneous with a kidney, 142 after a kidney, and 188 alone for nonuremic diabetic patients; again, the results have improved: by the 1990s, graft survival rates were similar in the 3 recipient categories. Successful pancreas transplants have been shown by our coworkers to stabilize or improve neuropathy and prevent recurrence of diabetic nephropathy in kidney grafts. In an attempt to simplify endocrine replacement therapy, we have done 63 human islet transplants, 34 as allografts for patients with type I diabetes and 29 as autografts after total pancreatectomy to treat chronic pancreatitis. Insulin independence occurs for about 50% of islet autograft recipients. Two recent islet allograft recipients treated with 15-deoxyspergualin have had sustained insulin independence. We anticipate that endocrine replacement therapy by transplantation will become routine for diabetic patients as methods to prevent rejection are refined.

The Defective Glucagon Response From Transplanted Intrahepatic Pancreatic Islets During Hypoglycemia Is Transplantation Site–Determined

The optimal site for pancreatic islet cell transplantation is presently unclear, although the liver has been the most commonly used. However, glucagon secretion from islets that have been autotransplanted in liver has been reported to be unresponsive to hypoglycemia yet responsive to arginine. To determine whether this selective glucagon secretory defect is related to the intrahepatic site of islet implantation or to the process of transplantation per se, we studied counterregulatory responses to hypoglycemia in dogs with pancreatic islet autotransplantation in the hepatic parenchyma (the intrahepatic [IH] group, n = 9) or the peritoneal cavity (the intraperitoneal [IP] group, n = 9), following total pancreatectomy, and compared them with the responses in normal controls (n = 10). Dogs were subjected to a hypoglycemic hyperinsulinemic (5 mU · kg−1 min−1) clamp for 90 min under general anesthesia. Arterial glucose concentrations were clamped at 2.7 mmol/l for the final 45 min of the clamp. Immediately following the clamp, glucagon responses to IV arginine (5 g) were also assessed. During hypoglycemia, glucagon responses in the IH group (maximal incremental glucagon = 33 ± 21 ng/l; glucagon area under curve [AUC] = 713 ± 1,022 ng · 1−1 · min−1) were significantly lower than either the IP (maximal incremental glucagon = 92 ± 32 ng/l; glucagon AUC = 4,090 ± 1,600 ng · 1−1 · min−1) or control (maximal incremental glucagon = 154 ± 71 ng/l; glucagon AUC = 6,943 ± 2,842 ng · 1−1 · min−1) group (IH vs. IP group, P < 0.05; control vs. IH group, P < 0.01). Glucagon responses in the IP group did not differ significantly from the control group. Epinephrine responses to hypoglycemia were similar in all groups, whereas neither of the transplanted groups (IH and IP) had pancreatic polypeptide responses. There was a prompt rise in plasma glucagon after intravenous arginine in all groups. These data indicate that glucagon unresponsiveness to hypoglycemia is specific to intrahepatically transplanted islets, rendering the liver a disadvantageous site for optimal α-cell function.

Distant processing of pancreas islets for autotransplantation following total pancreatectomy.

BACKGROUND Small duct chronic pancreatitis is associated with intractable pain and failure to thrive, usually unresponsive to conventional management approaches. Total pancreatectomy is considered after failure of medical intervention. The major morbidity following total pancreatectomy is diabetes mellitus with its associated complications. This adverse outcome can be mitigated through autotransplantation of islets recovered from the pancreatectomy specimen. This approach has been limited historically owing to the absence of an on-site islet processing facility. We present the results from 5 pancreatectomized patients whose islets were prepared 1,500 miles away. METHODS Five patients (4 women, 1 man, average age 42 years) who failed medical therapy and were not candidates for longitudinal pancreaticojejunostomy underwent total/completion pancreatectomy (4 total, 1 completion) for intractable symptoms from idiopathic small duct chronic pancreatitis. The resected pancreata were preserved in ViaSpan solution and were transferred to an islet processing laboratory by commercial airliner and returned. The dispersed pancreatic islet tissue was infused into a portal vein tributary through an operatively placed catheter after systemic heparinization. RESULTS All 5 patients experienced complete relief from pancreatic pain; 2 had significant residual discomfort from underlying Crohns disease. Three of the 5 patients had minimal or no insulin requirement after autotransplantation (median follow-up of 23 months); 1 patient continued with glycemic control difficulties related to Crohns disease. One patient died 17 months following autotransplantation from an unrelated pneumonia. CONCLUSION Total pancreatectomy with autologous islet transplantation can offer patients with idiopathic small duct chronic pancreatitis pain relief without the sequelae of diabetes mellitus and can be performed without an on-site islet processing facility. All patients undergoing total/ completion pancreatectomy should be considered candidates for this procedure.

Transcontinental Shipping of Pancreatic Islets for Autotransplantation After Total Pancreatectomy

Islet autotransplantation prevents diabetes in some patients after total pancreatectomy. Pancreatectomy is done at most hospitals but islets are prepared at only a few centers. We report a case in which the pancreas was sent to a laboratory half a continent distant from the operative site, and islets were prepared and returned to the original hospital for autotransplantation 16 h after resection. At 10 months posttransplantation, the patient is normoglycemic and insulin independent, with an appropriate insulin secretion in response to glucose. Endocrine function can be retained after pancreatectomy even if the islets are isolated at a remote laboratory, and autotransplantation could be offered to patients without the need to travel. This outcome implies that the typical handling and processing of a pancreas destined to yield an islet allograft should not prevent the recovery of a sufficient number of viable β cells to establish insulin independence in type 1 diabetic recipients.

Mycoplasma hominis Infections Occurring in Cardiovascular Surgical Patients

BACKGROUND Postoperative Mycoplasma hominis sternal would or mediastinal infections are uncommon and difficult to diagnose. Atypical growth characteristics in routine bacterial culture, and the inability to demonstrate the organism on Gram stain, lead to delayed diagnosis of M hominis infections and increased morbidity. METHODS Postoperative purulent would drainage or acute mediastinitis caused by M hominis developed in 3 cardiovascular surgery patients. These patients were considered along with 9 patients previously reported in the literature. RESULTS Operative findings included moderately thick, gray purulent fluid with the degree of tissue necrosis related to duration of infection. Intraoperative Gram stain of wound or mediastinal drainage demonstrated no microorganisms, and initial bacterial cultures did not reveal microbial growth. After an average of 4.5 days of culture, minute translucent colonies of M hominis were identified. The institution of appropriate antimycoplasma therapy (doxycycline and clindamycin) was associated with clinical or microbiological cure in all patients. Sternal wound complications developed in 3 patients, and a chronic infection developed in 1 patient. CONCLUSIONS Empiric therapy for M hominis infection should be considered in patients with mediastinitis or a sternal wound infection in which organisms are not observed on Gram stain and are not readily cultured.

A deeply invasive Phoma species infection in a renal transplant recipient

Phoma sp, a fungus routinely isolated from the soil and a known plant pathogen, was found to be the cause of an aggressive, deep compartment hand infection in a renal transplant recipient. Previous reports have described minimally invasive Phoma sp infections with isolates recovered from the skin or subcutaneous tissue. This case, however, is the first reported in which Phoma sp was found to be both aggressive and deeply invasive. Histologic sections obtained from the synovium of the fourth and fifth dorsal hand compartments revealed invasive hyphal elements. Detailed examination with Grocott-Gomori methenamine-silver staining revealed branching filaments and pycnidia. A Phoma sp was isolated from culture after 2 weeks of incubation. Antifungal agent sensitivity testing found the organism to be sensitive to amphotericin B but resistant to both fluconazole and 5-flucytosine. Treatment required surgical debridement and the use of prolonged systemic amphotericin B therapy in order to effect cure. This is a unique case of a deeply invasive Phoma sp infection, indicating that such processes are not strictly indolent as previously reported.

Islet autotransplantation after total pancreatectomy in a child

Islet autotransplantation can prevent surgically induced diabetes after total pancreatectomy in adults; however, the efficacy of this procedure has not been established in children. The authors report the case of a 12-year-old boy who underwent total pancreatectomy and islet autotransplantation for intractable pain caused by idiopathic chronic pancreatitis. Islets were prepared from the excised pancreas by collagenase digestion and mechanical dispersion. The resultant preparation, containing 109,500 islets, was injected into the recipients liver via the portal vein. No complication from the pancreatectomy or transplant occurred. Postoperatively, the patient had complete relief of abdominal pain. He remained insulin-independent, with normal fasting blood glucose and hemoglobin A1c levels, for 21/2 years. Preoperatively, the acute insulin response and the rate of glucose disappearance (Kg) were 213 microU/mL and 2.14% (respectively) after intravenous administration of 20 g of glucose. Although lower than pretransplantation values, both insulin response and Kg remained normal at 4 months (88 microU/mL; Kg, 1.01%); however, these decreased further, to below normal, by 2 years posttransplantation (10 microU/mL; Kg, 0.67%). Two-and-a-half years after transplantation, fasting hyperglycemia (> 200 mg/dL) was evident, and the patient was begun on exogenous insulin. Five years posttransplantation he remains insulin-dependent with a fasting serum C-peptide level of 0.20 ng/mL, which increased to 0.35 ng/mL in response to intravenous arginine, indicating sustained islet function. During the documented decreases in insulin secretion and Kg posttransplantation, the patients body weight increased by 65% (from 34 to 56 kg) as a result of normal growth; the number of transplanted islets relative to body mass decreased accordingly, from 3,200 to 1,950 islets per kilogram of body weight. In this case, the number of islets transplanted likely could not meet the increased insulin demands of the larger body mass. Thus, exogenous insulin supplementation was needed to prevent hyperglycemia. In conclusion, insulin independence was initially established in a child by islet autotransplantation after total pancreatectomy. The failure of the islets to maintain normoglycemia long-term suggests that a sufficient number must be transplanted (to meet the demands of normal growth and development) for sustained insulin independence.

Total lymphoid irradiation, without intrathymic injection of donor cells, induces indefinite acceptance of heart but not islet or skin allografts in rats

Abstract  Allograft tolerance oc curs in rodents given a dose of anti‐lymphocyte serum (ALS) and intra thymic injection (ITI) of donor splenocytes (SC) 1–3 weeks prior to transplant (TX). The purpose of our study was to test total lymphoid irradiation (TLI) as an alternative to ALS in ITI tolerance induction to heart, islet, and skin allografts. Pre‐pubertal Wistar Furth rats were recipients. ITI of donor (Lewis) SC was done at the end of the TLI course. Rats received either a het‐erotopic heart, a skin graft, or 2300 islets (diabetic recipients) intraportally from Lewis donors. TLI (with out ITI) in a dose of 200 rads/day for 5 consecutive days, followed by TX in 3 weeks resulted in indefinite ac ceptance of heart (but not islet or skin) grafts in 60 % of the recipients. These data indicate that TLI by a dose schedule of 200 rads/day for 5 days should be tested for clinical relevance in large animal recipients of immediately vascularized grafts.

Allograft tolerance by intrathymic donor splenocyte transfer: an age-dependent, species-specific phenomenon?

Abstract  Protocols that allow al lograft survival without immuno‐suppression remain the ultimate goal in transplantation. Intrathymic injection of donor splenocytes into a transiently immunosuppressed recipient has induced tolerance to a variety of subsequently transplanted allografts in rats. The purpose of this study was to determine if recipient age is critical to intrathymic tolerance in light of age‐dependent thy‐mic changes, and if this protocol can be extended to an outbred, large animal model. Prepubertal and postpubertal Wistar‐Furth rats underwent intrathymic injection of splenocytes from Lewis rats and an‐tilymphocyte serum (ALS) intra‐peritoneally. On day 21, a hetero‐topic Lewis heart was transplanted, with graft survival evaluated by car diac palpation. Graft tolerance (> 100 days) occurred in four out of five (80%) of the prepubertal rats compared to two out of six (33%) postpubertal rats. Tolerance was not demonstrated in rats receiving in trathymic injection of buffer only. In puppies, groups 1 and 2 underwent splenectomy with intrathymic injection of allo splenocytes. Control puppies (group 3) received intrathymic auto splenocytes. Groups 1 and 3 were given antilymphocyte gamma globulin (ALG) on days 7 to 0 with respect to the intrathymic injection. Group 2 did not receive ALG, but instead received cyclosporin A (CSA) on days 0–2. On day 21, all puppies underwent bilateral ne‐phrectomy and single renal trans plantation. No additional immuno‐suppression was given. Tolerance (creatinine < 7 mg/dl for 100 days) was not obtained by any dog in all three groups. There was no difference in graft survival between control and experimental dogs, with the longest surviving graft seen in a control dog (26 days). Our results suggest that thymic change during maturation may alter the ability to induce tolerance by intrathymic injection of donor cells in rats, and that the protocol is not easily adapted to large animals.

Clinical islet transplantation

The ultimate goal of beta cell transplantation is to improve the quality of life and to prevent the severe acute and the devastating chronic complications of diabetes, by utilizing isolated allogeneic human or xenogeneic porcine islets early in the course of type 1 diabetes. An additional aim is to minimize the use of long-term immunosuppression that is currently needed to prevent islet rejection and autoimmune recurrence of diabetes [1–3]. Several increasingly complex steps will have to be taken to reach this final objective and it is evident that the immunological obstacles, particularly those involved in pig-to-man islet xenotransplantation [4], are formidable and can only be overcome by continued research efforts directed towards the problems peculiar to isolated islets.