Bioenergetics in Hypertrophied and Remodeled Left Ventricle

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DESCRIPTION (provided by applicant): The inner layers of the left ventricular wall (ENDO) are known to be the most susceptible to oxidative stresses. We hypothesize that there is transmural gradient of reserves of ATP production rate via both creatine kinase (CK) and ATPase, which is the lowest in ENDO that results in the ENDO vulnerability in LVH hearts. Despite the intense interest in cellular therapy for myocardial repair, the majority of research reports to date have been designed to repair or prevent LV dysfunction in hearts with myocardial infarction secondary to coronary arteries diseases. Given the fact that more than 50% of heart transplant CHF patients whose etiology is nonischemic, studies using nonischemic large animal model is urgently needed before pursuing large scale clinical trials. The mechanisms underlying the beneficial effects of cellular therapy are not well defined. It is a consistent finding that the engraftment rate is low. However, the long term improvement of the LV contractile function of the recipient heart is consistently observed. Therefore, in addition to the myocardial regeneration from the engrafted cells the improved LV chamber function is also likely related to the changes of the recipient myocardial protein deferential expression. Comparing two swine models of LVH secondary to pressure overload or to postinfarction LV remodeling, the effects of MSCs transplantation on LV contractile function (MRI); myocardial perfusion, myocardial oxygenation level (1H-MRS); and ATP turnover rate (31P- MRS) will be measured biweekly for 8 weeks, the recipient myocardial differential protein expression will be examined by comparative proteomics. The specific aims are: SA1. Using the recently developed T1-nom P-31 magnetization saturation transfer (MST) methods to examine whether the myocardial ATP turnover rate via CK and ATPase are most severely altered in the ENDO of LVH hearts, and whether the severity of which is linearly related to the severity of the LV dysfunction. SA2. To examine whether the functional beneficial effects of allogenic MSC transplantation are accompanied by the improvement of ATP production capacity via CK and ATPase in the ENDO of LVH hearts with or without ischemic coronary artery diseases, and whether these functional benefits are accompanied by regeneration of myocardium from both engrafted MSCs as well as endogenous CPCs. SA3: To examine whether the functional beneficial effects of cellular therapy are associated with the differential protein expression profle of the recipient myocardium. We will employ cutting edge liquid chromatography mass spectrometry-based comparative proteomics method to quantitatively determine the changes in the protein expression with a special emphasis on growth factors family proteins and proteins involved in energy metabolism. The findings of the experiments will elucidate for the first time, the transmural gradient of ATP turnover rate via both CK and ATPase in the in vivo LVH hearts. The findings of these studies will advance our understanding of the mechanisms of cellular therapy in myocardial repair, and lead to better diagnostic and therapeutic modalities for CHF patients.