Development of a Novel Targeting and Signal Transduction System for Stem Cell Programming
Cardiovascular disease (CVD) is the leading cause of death in the US with an estimated 60 million patients whose care results in approximately $186 billion in annual costs. There is an urgent need for new therapies for acute and chronic myocardial ischemia (MI) and chronic heart failure (CHF) that often develops subsequent to MI. Stem cell (SC) therapy holds great promise for the repair of damaged heart tissue. However, many fundamental issues relating to repair remain unsolved, such as need to efficiently target the cells to the damaged tissue, integrate the cells into the heart, promote their viability, and stimulate new blood vessel growth. We propose to use the tools from the rapidly evolving field of synthetic biology to build an integrated system to target ES-derived myocardiocytes to infracted myocardium and once there, transduce intracellular signals to drive the expression of effectors to promote cell integration and new blood vessel growth. At the heart of the system are fusion proteins that use either an extracellular single chain antibody or a receptor-binding ligand for targeting and intracellular domains that upon dimerization of two extracellular domains, reconstitute an artificial transcription factor, lexA-VP16 to drive the expression of effector genes that confer appropriate phenotype. This fusion protein and the effectors needed for integration, viability and blood vessel growth will be introduced into cardiomyocytes derived from adult stem cells or embryonic stem (ES) cells. Preliminary efficiency of targeting and repair of damaged myocardium will be assessed. Our system will help improve the efficacy of current stem techniques which are too dependent upon stem cells and their differentiated progeny exhibiting repair behavior that they do not intrinsically possess. ES cells can recapitulate development and adult stem cells have some innate repair capacity, but they do not possess repair or regenerative capacity not already selected by evolution. Our system represents one way to overcome these limitations and engineer appropriate repair behavior. Proof of principle of this prototypical system will not only lead to new therapies for myocardial infarction, but also to the development of a similar systems to repair other damaged tissue by simple substitution of appropriate targeting scFv’s and intracellular effectors.
The development of a universal signaling and target system for ES and adult stem cell programming will enable repair of damaged tissue in patients. ES cells and adult stem cells are limited by evolution in their ability to repair or regenerate tissue. The system and tools provided will create a general framework to extend the capabilities of these cells to enable practical therapies. Californians will benefit by the development of practical therapies based on this framework.