SBIR-STTR Award

The purpose of this proposal is to provide proof-of-concept that a novel therapy that prevents complement activation could be effective in reducing ischemia reperfusion injury (IRI) in transplanted organs. Complement activation after IRI in transplanted organs is a well-known phenomenon that may be responsible for delayed graft function and the hastening of acute rejection. The proposed therapy to reduce IRI is based on novel fusogenic lipid vesicles (FLVs) that rapidly incorporate into cell membranes. Our FLVs allow the rapid display of protective exogenous proteins on the surface of endothelial cells. The goal of this proposal is to optimize the display of a modified complement blocking protein named vaccinia virus complement control protein (VCP) on the surface of endothelial cells, and show that it can reduce complement induced damage after cells are exposed to hypoxia and reoxygenation. We hypothesize that the VCP displayed on the surface of endothelial cells will bind complement fragments early in the complement cascade and prevent cell injury. To test this hypothesis, we will perform the following specific aims. In Aim I, the formulation and concentration of biotinylated lipid vesicles will be optimized for optimal biotin coverage of cells. Aim II will assess on the surface of endothelial cells the biotin binding capacity of the streptavidin domain on our recently developed streptavidin-VCP (SA-VCP) chimeric protein. Aim III will assess the ability of SA-VCP to inhibit complement derived damage, after hypoxia and reoxygenation, of endothelial cells. If this proposal is successful it will demonstrate the effectiveness of both our novel cell membrane biotinylation platform technology and our newly developed anti-complement chimeric protein. In a Phase II proposal, we plan to test our technology in a transplantation animal model. We believe that our technology will make it possible to rapidly modify the functional characteristics of endothelial cell membranes without the use of gene therapy. If SA-VCP ex-vivo therapy is highly effective in preventing complement activation after IRI this will be extremely valuable for organ transplantation. The economic implications of our technologies for clinical application are vast.

Tissue and organ transplantation procedures save and/or improve the lives of hundred of thousands of patients annually in the US. The goal of this research is to develop a local anti-complement therapy for donor organ ex vivo application that will reduce complement-induced injury to the vascular endothelium. An unavoidable consequence of transplantation (allografts or autografts) is ischemia/reperfusion (IR) injury. Studies have shown that IR-induced complement activation leads to the formation of several key inflammatory mediators that alter vascular homeostasis and stimulate leukocyte activation and chemotaxis. After decades of neglect, complement has been rediscovered as a potent mediator of inflammation and rejection in organ transplants. In Phase I of this proposal, we successfully provided proof-of-concept that our novel therapy reduced complement deposition in vitro after activation of the classical pathway. Our therapy is based on a platform technology that allows the rapid display of protective exogenous proteins on the surface of cells during organ harvest. The goal in Phase II is to prepare the technology for clinical use. This will be accomplished by developing safe and stable lyophilized components, which upon reconstitution, are perfused into organs ex vivo to effectively reduce locally complement mediated injury in vivo. The technical objectives are: 1) Reduce cost of therapeutic formulations by using the most economical components without compromising anti-complement efficacy. 2) Determine potential toxicity of therapy and demonstrate its efficacy in a kidney rat model of IR. 3) Develop stable lyophilized therapeutic components for storage and demonstrate in vitro that reconstituted components are just as effective as freshly prepared components. 4) Demonstrate in kidney rat models of IR and transplantation that lyophilized products are effective in reducing antigen-independent and antigent-dependent IR injury. If successful these studies will demonstrate the potential clinical value of our therapy in enhancing natural anti-complement defenses in allografts. Our therapy will be applied during routine flushes of donor organs and will achieve therapeutic levels of drug locally without systemic adverse effects. Application of our therapy may extend the donor pool by allowing organ harvest from non-beating heart donors. Our approach is a faster alternative to gene therapy, in that proteins can be displayed on the cell membranes in less than 1 hour. The economic implications for this novel therapeutic approach in transplantation are vast, not only in terms of the potential benefits to patients but also in reducing health care costs associated with re-operations and complications arising from failed procedures.

Public Health Relevance:
The goal of this project is to develop a new targeted therapy that prevents damage to transplanted organs. An unavoidable inherent problem of transplantation is that blood flow during organ harvest must be cutoff and later reestablished during implantation. This process causes the activation of the immune component called the complement system, which causes unintended tissue injury that ultimately leads to organ malfunction and failure. Anti-complement agents that are administered systemically have been developed but their use leaves transplant recipients vulnerable to viral and bacterial infections. EndoProtech, Inc. is proposing to develop a novel safer anti-complement therapeutic agent that binds to cells of transplanted organs and eliminates systemic circulation of the agent. The therapy is applied during harvest while organs are outside the body before implantation. The objective is to protect tissues from complement-related injury with minimal side effects.

Public Health Relevance:
This Public Health Relevance is not available.

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