Tissue Collection for Disease Modeling
Congenital heart defects (CHD) are among the most common birth defects, and account for the largest proportion of infant mortality due to birth defects. Despite its common occurrence, genetic complexity, important clinical symptoms, and possible environmental effects, investigation of the mechanism of CHD has lagged far behind adult cardiovascular disease. Absence of specific disease classification and lack of clear understanding of this serious newborn problems have resulted in poor diagnosis and therapy of CHD. Tetralogy of Fallot (ToF) is the most common type of severe CHD with highly consistent symptoms and known association with genetic abnormality. The occurrence of ToF in California, the US, and worldwide is approximately 1 in 2,000 live births making this the most common type of CHD requiring surgery. In this proposal, a multi-disciplinary effort, including geneticists, pediatricians, computer scientists, cardiologists, peri-natologists, and stem cell biologists, will study the modified cells generated from patients with ToF. A robust and innovative platform, employing the placenta-derived stem cells from ToF infants, will allow non-invasive generation of modified cells (induced pluritotent stem cells, iPSCs) and modified (iPSC-derived) heart cells. [REDACTED] is a national referral center for ToF. We propose to collect 40 ToF and 20 normal placentas per year.
Statement of Benefit to California:
The prevalence of tetralogy of Fallot (ToF) in California is approximately 1 in 2,000 live births making this the most common type of serious congenital heart disease requiring surgery. Congenital heart defects (CHD) are among the most common birth defects, and results in the largest proportion of infant mortality due to birth defects. Despite the common occurrence of CHD and their complex clinical findings, investigation of CHD has lagged far behind adult cardiovascular disease. Absence of well-defined disease classification and lack of clear understanding of this serious newborn problems have resulted in poor diagnosis and therapy. The proposed investigation of ToF may address the criticcal issues in studying CHD. The anatomic abnormalities of ToF are more consistent and better defined. Specific genetic abnormalities associated with ToF have also been identified. In this proposal, a multi-disciplinary collaboration among doctors and scientists from different fields will study iPSCs generated from patients with ToF. A reliable platform, employing the placenta-derived stem cells from ToF infants, will allow non-invasive, patient-specific generation of iPSCs and iPSC-derived cardiomyocytes. [REDACTED] is a national referral center for ToF. We are confident that we wil be able to collect 40 ToF placentas per year as described in our proposal.
Tetralogy of Fallot (ToF) is one of the most common congenital heart defects requiring surgery, with an incidence in 1/2000 live births. Untreated ToF causes mixing of oxygenated and deoxygenated blood in the left ventricle and subsequently right ventricular hypertrophy. In this proposal, the applicant intends to collect placentas from 40 infants with ToF and 20 normal controls per year over the two-year award. Amniotic mesenchymal stem cells (MSCs) from each tissue sample would be characterized and then sent to the Deriver for reprogramming into induced pluripotent stem cells (iPSCs). The applicant then intends to use cardiomyocytes differentiated from these iPSC to study the cellular and molecular defects underlying ToF. In addition, the applicant would collect and store extensive clinical data corresponding to each patient. Impact and Significance - The current understanding of the mechanism by which ToF arises is limited, and if a new resource, as proposed here, enabled the study of ToF pathogenesis, this could have significant impact. Rationale - Reviewers were not convinced that iPSC-derived cardiomyocytes, as proposed, would make a suitable model for ToF, since it is not known what other cell types in the developing heart might be affected instead of or in addition to cardiomyocytes. While these concerns reduce the enthusiasm for the proposed narrow focus on cardiomyocytes, reviewers acknowledged that other cell types, if appropriate, could be derived from iPSC as well. - Reviewers acknowledged that since iPSC-derived cardiomyocytes tend to be embryonic in their characteristics, they may represent an appropriate stage of development for modeling ToF, which is a developmental disorder. However, there was a major concern that it may not be straightforward to model ToF using hiPSC, as it may be necessary to recapitulate the complexities of cell-cell interactions, cell migration and patterning that occurs during development. - The PI did not provide a compelling rationale for using amniotic MSCs as a tissue source. Reviewers felt that using blood or skin fibroblasts would be more convenient and would dramatically lower the cost per sample. Quality of the Proposed Protocols - A major flaw of this proposal was the fact that many of the proposed activities were beyond the scope of the RFA. Much of the application focused on studies designed to characterize patient iPSC-derived cells and to develop a diagnostic tool, rather than focusing on the acquisition of donor cells for iPSC generation, which is the intent of the RFA. Feasibility - The PI did not adequately address how to obtain placentas from subjects whose diagnosis of ToF may not be made until hours or days after birth. It was not clear what percentage of patients were diagnosed prenatally. - The existing infrastructure for data collection and informatics support was deemed a strength. However, reviewers suggested that the PI must identify the appropriate subset of collected data to transfer to the repository where the patient iPSC lines would eventually be stored. Budget - Reviewers felt that the cost per cell line was very high. The proposed tissue source, amniotic MSC, is far more costly to procure than other sources such as blood or skin and was not well justified. In addition, the personnel and supplies costs appeared to be excessive. Qualifications of the Principal Investigator (PI) and Team Members, Resources - The PI is highly experienced and has assembled a multidisciplinary team that is well qualified to conduct the proposed work. - The research environment is outstanding and has the resources to successfully undertake the proposed work.