Bioengineering Islets with Aptamers That Block IBMIR in Islet Transplantation
Abstract
Type 1 diabetes (T1D) is a major health crisis with more than $200 billion in direct medical costs including the costly insulin injection for nearly 3 million people in the United States alone. T1D affects people of all ages and can severely affect their quality of life. Military personnel and their family members can also be afflicted by T1D, and this can hurt their quality of life. T1D can be managed by daily insulin injections; however, this has a negative side-effect and can lead to other health complications. Islet cell transplantation (ICT) has emerged as a promising long-term solution to replace insulin-producing islet cells; however, it is susceptible to an unwanted reaction called instant blood-mediated inflammatory reaction (IBMIR) that leads to early cell death. This proposal aims to prolong the insulin-independence period after islet transplantation by blocking IBMIR. Therefore, this study addresses the FY21 PRMRP topic area of Diabetes specifically focusing on improving the transplantation of pancreatic islet cells for long-term insulin production. Islet cell transplantation replaces the insulin-producing beta cells that are lost in T1D and can return normal blood glucose levels naturally. However, due to certain inflammatory events that occur during islet transplantation, a large number of islets are destroyed before getting engrafted. This is because islets are clinically administered through the portal vein (blood), which triggers an immediate inflammatory response called IBMIR, ultimately resulting in significant loss of transplanted islet mass (more than 50%). The transplanted islets are then exposed to pro-inflammatory proteins interleukin-1 beta (IL-1beta) and tumor necrosis factor-alpha (TNFalpha) released by the patrolling immune cells. These proteins can result in apoptosis or programmed cell death of islets. The goal of this proposal is to improve islet transplantation outcomes by blocking IBMIR by inhibiting coagulation and apoptosis. To inhibit these proteins involved in coagulation and islet cell apoptosis, we will use specific RNA/DNA sequences called aptamers that bind to these proteins with high affinity and specificity and inhibits their functions. Specifically, human islets will be engineered using chemical crosslinking to carry aptamers to the site of transplantation. The key advantage of this approach is that encapsulation of aptamers to the surface of the islet will increase the local concentration of the aptamers at the site of transplantation and also prevent off-target effects. To test our hypothesis that the transplantation of aptamer bioengineered islets will prevent the activation of IBMIR and improve the islet graft survival and long-term insulin independence outcomes, we will pursue three specific aims. In the first aim, we will design aptamers and characterize and optimize them to increase the binding strength and inhibitory potential of the aptamers. The aptamer-protein interactions will be determined using single-molecule fluorescence microscopy and nuclear magnetic resonance (NMR) techniques. In the second aim, we will test the anti-inflammatory and cytoprotective ability of IL-1beta and TNFalpha aptamers on human islets. In the third specific aim, the anti-coagulant potential of FVIIa aptamer will be tested using healthy human plasma. Moreover, using an animal model of islet transplantation, we will evaluate the ability of aptamer-engineered islets to block IBMIR. Successful completion of this research will be further developed using preclinical studies and large animal models to determine the large-scale potential of this approach. In the future stages, we plan to expand this novel aptamer-based therapeutic approach to target other proteins to eliminate the need for lifelong immunosuppressive drugs. Therefore, the scope of this study is broad and will have a major positive impact on the type-1 diabetic community.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 28, 2022
- Source ID
- W81XWH2210102
Entities
People
- Mazhar Kanak
Organizations
- United States Army
- Virginia Commonwealth University