Dr. Kieran Clarke
University of Oxford

Cardiac stem cells to prevent heart failure – An MR study

Heart disease has been identified as relevant within the realm of health disparities. The “Strategic Research Plan and Budget to Reduce and Ultimately Eliminate Health Disparities - Volume I,” published by the National Institutes of Health indicates that coronary heart disease mortality is 20 percent higher for African Americans than Whites and the incidence of stroke is disproportionately high in African Americans.
See (http://ncmhd.nih.gov/our_programs/strategic/pubs/VolumeI_031003EDrev.pdf)

A promising, novel approach to the treatment of myocardial infarction and the prevention of heart failure is cell grafting in the damaged myocardium. The aim of this project is to determine whether cardiac muscle and vasculature can be formed from cardiac-derived stem cells (CSCs) to restore function and metabolism after coronary occlusion. CSCs will be isolated, expanded, characterized and transplanted into the chronically infarcted rat heart in vivo. The effects of the transplanted CSCs on heart function will be monitored non-invasively using magnetic resonance imaging (MRI). We propose to determine the optimal method of cell delivery and timing of cell implantation post infarction. We will also use magnetic resonance spectroscopy (MRS) to determine the extent to which the implanted stem cells prevent changes in myocardial energetics, mitochondrial function and substrate metabolism that are associated with remodelling in the failing heart. This project will combine stem cell experience with cardiac MR, physiological and biochemical expertise.

Our hypothesis is that functional cardiomyocytes, endothelial cells and vascular smooth muscle cells can be derived from primitive cells found in the heart and that these cells have the potential for treating the infarcted and/or failing heart. The student will isolate, expand and characterize the CSCs. They will then determine the therapeutic potential of these autologous CSCs in vivo in a rat chronic infarct model of heart failure by monitoring their effectiveness in controlling infarct expansion and remodelling, using MRI and MRS, and to determine the optimal method and timing of cell delivery.

The student would prepare cardiac stem cells, grow them on biomembranes, transduce them with GFP, label them with iron oxide particles and introduce the cells into the area of the infarct. Control groups will be injected with culture medium or non-functional control cells. Infarcts will be produced using left anterior descending coronary artery ligation and stem cells will be either administered via tail vein infusion or injected into the border zone of the scar tissue, with or without a scaffold. The infarct size and global and regional cardiac function and morphology during remodelling and failure will be determined, regularly and non-invasively over the following weeks, using in vivo MRI. After several weeks, rat hearts will be isolated for histology and immunohistochemistry or perfusion in the MR spectrometer for measurement of energetics and pH using 31P MRS. Cardiac output and efficiency will be determined in the isolated working rat heart. Transplanted cells will be tracked using iron oxide with MRI and by their expression of GFP using immunohistochemistry to identify the expression of marker plus cardiac-specific proteins in the transplanted cells.

In this project, the student would be working with postdoctoral fellows who routinely use the methods involved. Consequently, they would quickly learn the experimental techniques and should complete part of the project within the time allowed.

References
1. Murray AJ, Lygate CA, Cole MA, Carr CA, Radda GK, Neubauer S, Clarke K. Insulin resistance, increased ischaemic damage and abnormal energy metabolism in the chronically infarcted rat heart. Cardiovasc Res 71: 149-157, 2006
2. Murray AJ, Panagia M, Hauton D, Gibbons GF, Clarke K. Plasma free fatty acids and peroxisome proliferator-activated receptor α in the control of myocardial uncoupling protein levels. Diabetes 54: 3496-3502, 2005.
3. Stuckey DJ, Carr CA, Martin-Rendon E, Tyler DJ, Willmott C, Cassidy PJ, Hale SJM, Schneider JE, Tatton L, Harding SE, Radda GK, Watt S, Clarke K. Iron particles for non-invasive monitoring of bone marrow stromal cell engraftment into, and isolation of viable engrafted donor cells from, the heart. Stem Cells 24: 1968–1975, 2006.
4. Tyler DJ, Lygate CA, Schneider JE, Cassidy PJ, Neubauer S, Clarke K. Cine-MR imaging of the normal and infarcted rat heart using an 11.7 T vertical bore MR system. J Cardiovasc Magn Reson 8: 327-333, 2006.
5. Wilding JR, Lygate CA, Davies KE, Neubauer S, Clarke K. MLP accumulation and remodelling in the infarcted rat heart. Eur J Heart Fail 8: 343-346, 2006.