Despite therapeutic advances, cardiovascular disease remains a leading cause of mortality and morbidity in both California and Europe. New insights into disease pathology, models to expedite in vitro testing and regenerative therapies would have an enormous societal and financial impact. Although very promising, practical application of pluripotent stem cells or their derivatives face a number of challenges and technological hurdles. For instance, recent reports have demonstrated that cardiac progenitor cells (CPCs), which are capable of differentiating into all three cardiovascular cell types, are present during normal fetal development and can be isolated from pluripotent stem cells. induced pluripotent stem cell (iPSC)-derived CPC therapy after a myocardial infarction would balance the need for an autologous, multipotent stem cell myocardial regeneration with the concerns of tumorigenicity using a more primitive stem cell. However, translating this discovery into a clinically useful therapy will require additional advances in our understanding of CPC biology and the factors that regulate their fate to develop optimized cell culture technology for CPC application in regenerative medicine.
Cardiac cell therapy with hiPSC-derived cells, will require reproducible production of large numbers of well-characterized cells under defined conditions in vitro. This is particularly true for the rare and difficult to culture intermediates, such as CPCs. Our preliminary data demonstrated that a CPC niche exists during cardiac development and that CPC expansion is regulated by factors found within the niche microenvironment including specific soluble factors and ECM signals. However, our current understanding of the cardiac niche and how this unique microenvironment influences CPC fate is quite limited. We believe that if large scale production of hiPSC-derived CPCs is ever to be successful, new 3D cell culture technologies to replicate the endogenous cardiac niche will be required. The goals of this proposal are to address current deficiencies in our understanding of the cardiac niche and its effects on CPC expansion and differentiation as well as utilize novel bioengineering approaches to fabricate synthetic niche environments in vitro. The development of advanced fully automated in vitro culture systems that reproduce key features of natural niche microenvironments and control proliferation and/or differentiation, are critically needed both for studying the role of the niche in CPC biology but also the advancement of the field of regenerative medicine.
Heart disease, stroke and other cardiovascular diseases are the #1 killer in California. Despite medical advances, heart disease remains a leading cause of disability and death. Recent estimates of its cost to the U.S. healthcare system amounts to almost $300 billion dollars. Although current therapies slow the progression of heart disease, there are few, if any options, to reverse or repair damage. Thus, regenerative therapies that restore normal heart function would have an enormous societal and financial impact not only on Californians, but the U.S. more generally. The research that is proposed in this application could lead to new therapies that would restore heart function after and heart attack and prevent the development of heart failure and death. We will develop the techniques to expand and transplant human cardiac progenitor cells. Combining tissue engineering with human pluripotent stem cells will facilitate the creation of new cardiovascular therapies.
This application aims to understand how cardiac progenitor cell (CPC) expansion and differentiation are regulated by the niche and to apply this knowledge to control CPCs in vitro, enabling their ultimate application as a cardiac regenerative therapy. First, the applicants plan to characterize the endogenous human CPC niche and engineer 3D niche matrices. Next, they will investigate the mechanisms by which the identified niche proteins and engineered 3D environments regulate human induced pluripotent stem cell-derived CPC (hiPSC-CPC) expansion and differentiation. Finally, the group will perform a screen to identify optimal matrices to support hiPSC-CPC proliferation and multipotency.
Significance and Innovation:
- This proposal addresses an important question. Stem cell therapies are already in clinical trials for cardiac disease and the applicant makes a good case that CPCs, once optimized for expansion and engraftment, could have improved therapeutic efficacy over cells currently in use.
- Understanding the CPC niche could also advance other stem cell therapies.
- The application is not particularly innovative in its proposed methods or materials.
Feasibility and Experimental Design:
- The research plan is logical and its feasibility is supported by preliminary data. Specifically, these data support the role of two endogenous niche proteins in CPC proliferation, the applicants╒ ability to engineer 3D niches, and their ability to identify human endogenous and hiPSC-derived CPCs using surface markers.
- The experimental plan is complex and sophisticated, which was cited as both a strength and a weakness. One reviewer noted that the three Aims are not well-integrated and lack a cohesive objective or hypothesis. This reviewer was particularly concerned that different materials are used to simulate the CPC niche in different aims.
- Reviewers had mixed opinions about the application╒s focus on the role of structural niche factors and exclusion of soluble factors that also may regulate CPC behavior. One reviewer described this as a serious omission, while another felt that its inclusion would render the plan overly complex.
- One reviewer suggested that the development of stage specific reporter genes could facilitate analysis of the screening studies in Aim 3.
Principal Investigator (PI) and Research Team:
- The PI is excellent and has the appropriate experience and track record in both cardiovascular research and tissue engineering.
- The overall team is very strong. It is enhanced by collaborations with both the Partner PI, who provides expertise in laser capture microdissection, and the Co-Investigator, who provides high throughput matrix screening capability.
- There are risks associated with coordinating a research project between three groups in three separate locales. However, the established relationship between the PI and Partner PI assured reviewers that this arrangement is feasible.
- Reviewers did express concern that while the project requires generation of adequate numbers of hiPSC-CPCs, the team lacks a human pluripotent stem cell expert.
Responsiveness to the RFA:
- The proposal is highly responsive to the RFA as it characterizes the fate of a human pluripotent stem cell derived progenitor as well as the mechanisms by which engineered microenvironments regulate cell fate.