Regulated hepatic insulin gene therapy of STZ-diabetic rats

Abstract

Effective and safe insulin gene therapy will require regulation of transgenic insulin secretion. We have created a livertargeted insulin transgene by engineering glucose responsive elements into a hepatic promoter containing an inhibitory insulin response sequence. In this work, we demonstrate application of this transgene for the treatment of diabetes mellitus in vivo, by administering a recombinant adenovirus vector, Ad/(GlRE) 3 BP-1 2xfur, to rats made diabetic with streptozotocin. We verified hepatic expression of transgenic insulin by RT-PCR, and confirmed glucose responsive stimulation of transgenic insulin secretion in vivo by serum RIA. Following a portal system injection of either Ad/(GlRE) 3 BP-1 2xfur, or an empty adenoviral vector, animals made diabetic with either low (120 mg/kg), or high (290 mg/kg) dose streptozotocin (STZ) were monitored for changes in body weight, and blood glucose. Without subcutaneous insulin injections, blood glucose values of sham-

Adult rat liver cells transdifferentiated with lentiviral IPF1 vectors reverse diabetes in mice: an ex vivo gene therapy approach

“…This has stimulated efforts to expand existing pancreatic islets or grow new ones. As beta cells have an extremely low replication rate [1], transplantation of non-beta cells that produce insulin has become a reasonable alternative [2][3][4][5][6][7][8][9][10][11][12].…”

Gene- and cell-based therapeutics for type I diabetes mellitus

“…Injection of animals with a number of vectors like adenovirus [124][125][126][127][128][129] and adeno-associated virus [130][131][132][133] encoding proinsulin under the control of a number of promoters including CMV, insulin, phosphoenolpyruvate carboxykinase (PEPCK) and L-pyruvate kinase (LPK) has resulted in correction of hyperglycemia. In many instances, however, the effect appears to have been transient.…”

“…[134][135][136][137][138] The most notable advances have been made using engineered hepatocytes. 126,128,129 Hepatocytes are particularly attractive because they can easily engraft in the liver, and because they possess identical glucose-sensing molecules as the pancreas (eg, GLUT2, glucokinase (GK)). Furthermore, one can exploit a number of hepatocyte gene promoters, which are sensitive to glucose, in order to engineer insulin transgenes to be glucose concentration-sensitive.…”

“…Furthermore, one can exploit a number of hepatocyte gene promoters, which are sensitive to glucose, in order to engineer insulin transgenes to be glucose concentration-sensitive. Despite a number of promising approaches exploiting a number of glucose-regulated promoters, 126,128,129,131,[139][140][141][142][143][144] much more work is needed to make hepatocytes into fully surrogate b cells. The first feature that a hepatocyte is missing to properly act like a b-cell surrogate is the ability to respond to glucose in a sufficiently rapid fashion, as rapid as that characteristic of b cells.…”

Vectors for the treatment of autoimmune disease

“…179 Similarly, targeted and regulated expression of insulin was facilitated by the inclusion of glucose response elements upstream of the insulin-like growth factor binding protein-1 basal promoter which contains inhibitory insulin response elements. 180 Other in vivo studies have also examined systems in muscle. 10,22 Transcriptionally regulated systems are characterized by a significant time lag (approximately 6 h) between induction of gene expression and protein synthesis.…”