Treatment of Diabetes and Long-Term Survival After Insulin and Glucokinase Gene Therapy

Abstract

Diabetes is associated with severe secondary complications, largely caused by poor glycemic control. Treatment with exogenous insulin fails to prevent these complications completely, leading to significant morbidity and mortality. We previously demonstrated that it is possible to generate a “glucose sensor” in skeletal muscle through coexpression of glucokinase and insulin, increasing glucose uptake and correcting hyperglycemia in diabetic mice. Here, we demonstrate long-term efficacy of this approach in a large animal model of diabetes. A one-time intramuscular administration of adeno-associated viral vectors of serotype 1 encoding for glucokinase and insulin in diabetic dogs resulted in normalization of fasting glycemia, accelerated disposal of glucose after oral challenge, and no episodes of hypoglycemia during exercise for >4 years after gene transfer. This was associated with recovery of body weight, reduced glycosylated plasma proteins levels, and long-term survival without secondary complications. Conversely, exogenous insulin or gene transfer for insulin or glucokinase alone failed to achieve complete correction of diabetes, indicating that the synergistic action of insulin and glucokinase is needed for full therapeutic effect. This study provides the first proof-of-concept in a large animal model for a gene transfer approach to treat diabetes.

Characterization of Insulin-Secreting Porcine Bone Marrow Stromal Cells Ex Vivo and Autologous Cell Therapy in Vivo

“…The fact that reports of gene and nonislet cell treatment in large diabetic animals are very sparse (9,14,43) highlights both the considerable challenges of large animal models and the urgent need to successfully scale-up small animal techniques as a prerequisite for human subject research. There are already preclinical studies of porcine BMMSCs in repair of skin (24), bone (52,65), articular cartilage (34), and ischemic myocardium (57).…”

Hydrodynamic Tail Vein Injection as a Simple Tool for Yielding Extended Transgene Expression in Solid Tumors

“…4,5) Such a high transgene expression is considered a preferable feature of hydrodynamic injection; since the liver is the main organ for metabolism, the method has been used in the treatment of congenital metabolic abnormalities 6,7) and metabolic syndromes. 8,9) Moreover, sufficient transgene expression was observed in other organs, while the expression levels were universally lower than those in the liver. 2) Meanwhile, solid tumors are another important target of transgene expression induced by hydrodynamic injection.…”

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“…For example, Bosch and colleagues targeted skeletal muscle cells, one of the primary targets of insulin action, and found that GK needed to be co-expressed with insulin to attain normoglycemia. 25 Similarly, Hughes and coworkers found that AtT-20ins cellsanterior pituitary cells that express GK but not GLUT2-needed to be cotransfected with insulin and GLUT2 to confer glucose-stimulated insulin secretion. 26,27 It would also be beneficial for the cellular target of gene therapy to be immunoprivileged, thus allowing it to evade preexisting autoimmunity.…”

“…As such, viral vectors have been used more prevalently in insulin gene therapy applications and are ultimately the future of the therapy. Adenoviruses, 34,36,37 adeno-associated viruses, 25,38,39 oncoretroviruses, 40,41 and lentiviruses [42][43][44] all have been used to deliver insulin to hepatocytes, but they vary in their ability to meet the essential criteria described previously. A summary of each viral vector's ability to meet the demands required for insulin gene therapy applications is included in Table 1.…”