Augmentation of transgene-encoded protein after neonatal injection of adeno-associated virus improves hepatic copy number without immune responses.

BACKGROUND: Achieving persistent expression is a prerequisite for genetic therapies for inherited metabolic enzymopathies. Such disorders potentially could be treated with gene therapy shortly after birth to prevent pathology. However, rapid cell turnover leads to hepatic episomal vector loss, which diminishes effectiveness. The current studies assessed whether tolerance to transgene proteins expressed in the neonatal period is durable and if the expression may be augmented with subsequent adeno-associated virus (AAV) administration. METHODS: AAV was administered to mice on day 2 with reinjection at 14 or at 14 and 42 d with examination of changes in hepatic copies and B and T cell-mediated immune responses. RESULTS: Immune responses to the transgene protein and AAV were absent after neonatal administration. Reinjection at 14 or at 14 and 42 d resulted in augmented expression with greater hepatic genome copies. Unlike controls, immune responses to transgene proteins were not detected in animals injected as neonates and subsequently. However, while no immune response developed after neonatal administration, anticapsid immune responses developed with further injections suggesting immunological ignorance was the initial mechanism of unresponsiveness. CONCLUSIONS: Persistence of transgene protein allows for tolerance induction permitting readministration of AAV to re-establish protein levels that decline with growth.

Autologous islet transplantation with remote islet isolation after pancreas resection for chronic pancreatitis.

IMPORTANCE: Autologous islet transplantation is an elegant and effective method for preserving euglycemia in patients undergoing near-total or total pancreatectomy for severe chronic pancreatitis. However, few centers worldwide perform this complex procedure, which requires interdisciplinary coordination and access to a sophisticated Food and Drug Administration-licensed islet-isolating facility. OBJECTIVE: To investigate outcomes from a single institutional case series of near-total or total pancreatectomy and autologous islet transplantation using remote islet isolation. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study between March 1, 2007, and December 31, 2013, at tertiary academic referral centers among 9 patients (age range, 13-47 years) with chronic pancreatitis and reduced quality of life after failed medical management. INTERVENTIONS: Pancreas resection, followed by transport to a remote facility for islet isolation using a modified Ricordi technique, with immediate transplantation via portal vein infusion. MAIN OUTCOMES AND MEASURES: Islet yield, pain assessment, insulin requirement, costs, and transport time. RESULTS: Eight of nine patients had successful islet isolation after near-total or total pancreatectomy. Four of six patients with total pancreatectomy had islet yields exceeding 5000 islet equivalents per kilogram of body weight. At 2 months after surgery, all 9 patients had significantly reduced pain or were pain free. Of these patients, 2 did not require insulin, and 1 required low doses. The mean transport cost was $16,527, and the mean transport time was 3½ hours. CONCLUSIONS AND RELEVANCE: Pancreatic resection with autologous islet transplantation for severe chronic pancreatitis is a safe and effective final alternative to ameliorate debilitating pain and to help prevent the development of surgical diabetes. Because many centers lack access to an islet-isolating facility, we describe our experience using a regional 2-center collaboration as a successful model to remotely isolate cells, with outcomes similar to those of larger case series.

Myocyte-mediated arginase expression controls hyperargininemia but not hyperammonemia in arginase-deficient mice.

Human arginase deficiency is characterized by hyperargininemia and infrequent episodes of hyperammonemia that cause neurological impairment and growth retardation. We previously developed a neonatal mouse adeno-associated viral vector (AAV) rh10-mediated therapeutic approach with arginase expressed by a chicken ß-actin promoter that controlled plasma ammonia and arginine, but hepatic arginase declined rapidly. This study tested a codon-optimized arginase cDNA and compared the chicken ß-actin promoter to liver- and muscle-specific promoters. ARG1(-/-) mice treated with AAVrh10 carrying the liver-specific promoter also exhibited long-term survival and declining hepatic arginase accompanied by the loss of AAV episomes during subsequent liver growth. Although arginase expression in striated muscle was not expected to counteract hyperammonemia, due to muscle's lack of other urea cycle enzymes, we hypothesized that the postmitotic phenotype in muscle would allow vector genomes to persist, and hence contribute to decreased plasma arginine. As anticipated, ARG1(-/-) neonatal mice treated with AAVrh10 carrying a modified creatine kinase-based muscle-specific promoter did not survive longer than controls; however, their plasma arginine levels remained normal when animals were hyperammonemic. These data imply that plasma arginine can be controlled in arginase deficiency by muscle-specific expression, thus suggesting an alternative approach to utilizing the liver for treating hyperargininemia.

Low rates of short- and long-term graft loss after kidney-pancreas transplant from a single center.

IMPORTANCE: Since the 1980s, pancreas transplant has become the most effective treatment strategy to restore euglycemia in patients with type 1 diabetes mellitus. However, technical complications and BK virus nephropathy continue to be important causes of early and late graft loss. These and other complications lead to cited 1- and 3-year graft survival rates of 74% and 67% (pancreas) and 81% and 73% (kidney). OBJECTIVE: To examine our center's outcomes with pancreas-kidney transplant and early BK virus screening and treatment. DESIGN: Prospective study from August 2004 to January 2012. SETTING: University medical center. PARTICIPANTS: Sixty-five patients with type 1 diabetes who underwent simultaneous kidney and pancreas, pancreas after kidney, or pancreas transplant alone at a single center. INTERVENTION: Pancreas transplant. MAIN OUTCOME MEASURES: Pancreas and kidney survival; patient survival; and kidney loss due to BK virus nephropathy. RESULTS: Patient survival at 1, 3, and 5 years was 100%, 98.4%, and 98.4%, respectively. Of 2 early pancreatic allograft losses, 1 was due to thrombosis (1.6%). One- and 5-year pancreas graft survival rates were 95.4% and 92.3%; losses after more than 1 year were due to rejection. Kidney survival rates were 100% and 95.2% at 1 and 5 years; losses were due to nephropathy and noncompliance, with 1 death with function. BK virus incidence was 29.2%, with no graft losses due to BK infection. CONCLUSIONS AND RELEVANCE: While pancreas transplant can be complicated by early graft loss, our results suggest that excellent outcomes at 5 years can be achieved. Posttransplant BK virus screening and treatment are essential tools to long-term success.