Mesenchymal stem cell injection after myocardial infarction improves myocardial compliance.
Cellular therapy for myocardial injury has improved ventricular function in both animal and clinical studies, though the mechanism of benefit is unclear. This study was undertaken to examine the effects of cellular injection after infarction on myocardial elasticity. Coronary artery ligation of Lewis rats was followed by direct injection of human mesenchymal stem cells (MSCs) into the acutely ischemic myocardium. Two weeks postinfarct, myocardial elasticity was mapped by atomic force microscopy. MSC-injected hearts near the infarct region were twofold stiffer than myocardium from noninfarcted animals but softer than myocardium from vehicle-treated infarcted animals. After 8 wk, the following variables were evaluated: MSC engraftment and left ventricular geometry by histological methods, cardiac function with a pressure-volume conductance catheter, myocardial fibrosis by Masson Trichrome staining, vascularity by immunohistochemistry, and apoptosis by TdT-mediated dUTP nick-end labeling assay. The human cells engrafted and expressed a cardiomyocyte protein but stopped short of full differentiation and did not stimulate significant angiogenesis. MSC-injected hearts showed significantly less fibrosis than controls, as well as less left ventricular dilation, reduced apoptosis, increased myocardial thickness, and preservation of systolic and diastolic cardiac function. In summary, MSC injection after myocardial infarction did not regenerate contracting cardiomyocytes but reduced the stiffness of the subsequent scar and attenuated postinfarction remodeling, preserving some cardiac function. Improving scarred heart muscle compliance could be a functional benefit of cellular cardiomyoplasty.
Division of Cardiothoracic Surgery, Department of Physiology, University of Pennsylvania School of Medicine, A700 Richards Bldg., 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA.
Mark F
MF
Berry
Adam J
AJ
Engler
Y Joseph
YJ
Woo
Timothy J
TJ
Pirolli
Lawrence T
LT
Bish
Vasant
V
Jayasankar
Kevin J
KJ
Morine
Timothy J
TJ
Gardner
Dennis E
DE
Discher
H Lee
HL
Sweeney
D000818:Animals; D003187:Compliance; D004548:Elasticity; D006439:Hemodynamics / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008648:Mesoderm / Q000166:cytology* / Q000473:pathology; D018625:Microscopy, Atomic Force; D009200:Myocardial Contraction / Q000502:physiology; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy*; D032383:Myocytes, Cardiac / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology; D051381:Rats; D011917:Rats, Inbred Lew; D033581:Stem Cell Transplantation; D020107:Troponin T / Q000378:metabolism
D020107:Troponin T