Background: Cell-based insulin therapies can potentially improve glycemic regulation in insulin-dependent diabetic patients. Enteroendocrine cells engineered to secrete recombinant insulin have exhibited glycemic efficacy, but have been primarily studied as uncontrollable growth systems in immune incompetent mice. Furthermore, reports suggest that suboptimal insulin secretion remains a barrier to expanded application.
Methods: Genetic and tissue engineering strategies were applied to improve recombinant insulin secretion from intestinal L-cells on both a per-cell and per-graft basis. Transduction of insulin-expressing GLUTag L-cells with lentivirus carrying an additional human insulin gene–enhanced secretion twofold. We infected cells with lentivirus expressing a luciferase reporter gene to track cell survival in vivo. To provide a growth-controlled and immune protective environment without affecting secretory capacity, cells were microencapsulated in barium alginate. Approximately 9×107 microencapsulated cells were injected intraperitoneally in immune competent streptozotocin-induced diabetic mice for therapeutic efficacy evaluation.
Results: Graft insulin secretion was increased to 16 to 24 mU insulin per day. Transient normoglycemia was achieved in treated mice two days after transplantation, and endogenous insulin was sufficient to sustain body weights of treated mice receiving minimal supplementation.
Conclusion: Glycemic efficacy of a bioartificial pancreas based on insulin-secreting enteroendocrine cells is insufficient as a standalone therapy, despite enhancement of graft insulin secretion capacity. Supplemental strategies to alleviate secretion limitations should be pursued.
1 School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA.
2 Section Endocrinology & Metabolism, Atlanta VA Medical Center, Division of Endocrinology, Lipids, & Diabetes, Emory University School of Medicine, Atlanta, GA.
3 Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA.
4 Address correspondence to: Athanassios Sambanis, Ph.D., School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 315 Ferst Dr. NW, IBB Building, Room 1306, Atlanta, GA 30332.
Funding source NIH (R01 DK076801). A.R.T. received additional support from the President’s Fellowship.
The authors declare no conflicts of interest.
A.R.T. and A.S. both contributed to the research design of the studies. A.R.T. performed all of the research experiments, conducted the data analyses, and wrote the article. A.S. and P.M.T. contributed to the review and revision of the article.
Received 17 March 2014. Revision requested 6 April 2014.
Accepted 9 April 2014.