Neovasculogenic therapy to augment perfusion and preserve viability in ischemic cardiomyopathy.
BACKGROUND
Ischemic cardiomyopathy is a global health concern with limited therapy. We recently described endogenous revascularization utilizing granulocyte-macrophage colony stimulating factor (GMCSF) to induce endothelial progenitor cell (EPC) production and intramyocardial stromal cell-derived factor-1alpha (SDF) as a specific EPC chemokine. The EPC-mediated neovascularization and enhancement of myocardial function was observed. In this study we examined the regional biologic mechanisms underlying this therapy.


METHODS
Lewis rats underwent left anterior descending coronary artery (LAD) ligation and developed ischemic cardiomyopathy over 6 weeks. Three weeks after ligation, the animals received either subcutaneous GMCSF and intramyocardial SDF injections or saline injections as control. Six weeks after LAD ligation circulating EPC density was studied by flow cytometry. Quadruple immunofluorescent vessel staining for mature, proliferating vasculature was performed. Confocal angiography was utilized to identify fluorescein lectin-lined vessels to assess perfusion. Ischemia reversal was studied by measuring myocardial adenosine triphosphate (ATP) levels. Myocardial viability was assayed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling detection of apoptosis and quantitation of myofilament density.


RESULTS
The GMCSF/SDF therapy enhanced circulating leukocyte (13.1 +/- 4.5 x 10(6) vs 3.1 +/- 0.5 x 10(6)/cc, p = 0.001, n = 6) and EPC (14.2 +/- 6.6 vs 2.2 +/- 2.1/cc, p = 0.001, n = 6) concentrations. Tetraimmunofluorescent labeling demonstrated enhanced stable vasculature with this therapy (39.2 +/- 8.1 vs 25.4 +/- 5.1%, p = 0.006, n = 7). Enhanced perfusion was shown by confocal microangiography of borderzone lectin-labeled vessels (28.2 +/- 5.4 vs 11.5 +/- 3.0 vessels/high power field [hpf], p = 0.00001, n = 10). Ischemia reversal was demonstrated by enhanced cellular ATP levels in the GMCSF/SDF borderzone myocardium (102.5 +/- 31.0 vs 26.9 +/- 4.1 nmol/g, p = 0.008, n = 5). Borderzone cardiomyocyte viability was noted by decreased apoptosis (3.2 +/- 1.4% vs 5.4 +/- 1.0%, p = 0.004, n = 10) and enhanced cardiomyocyte density (40.0 +/- 5.6 vs 27.0 +/- 6 myofilaments/hpf, p = 0.01, n=10).


CONCLUSIONS
Endogenous revascularization for ischemic cardiomyopathy utilizing GMCSF EPC upregulation and SDF EPC chemokinesis upregulates circulating EPCs, enhances vascular stability, and augments myocardial function by enhancing perfusion, reversing cellular ischemia, and increasing cardiomyocyte viability.
Atluri
Pavan
P
Division of Cardiothoracic Surgery, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Liao
George P
GP
Panlilio
Corinna M
CM
Hsu
Vivian M
VM
Leskowitz
Matthew J
MJ
Morine
Kevin J
KJ
Cohen
Jeffrey E
JE
Berry
Mark F
MF
Suarez
Erik E
EE
Murphy
Danielle A
DA
Lee
William M F
WM
Gardner
Timothy J
TJ
Sweeney
H Lee
HL
Woo
Y Joseph
YJ
D000818:Animals; D017209:Apoptosis; D002465:Cell Movement / Q000502:physiology; D002470:Cell Survival; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000494:pharmacology* / Q000627:therapeutic use; D004730:Endothelium, Vascular / Q000166:cytology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology* / Q000502:physiology; D019650:Hematopoietic Stem Cell Mobilization; D020287:In Situ Nick-End Labeling; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D051381:Rats; D011917:Rats, Inbred Lew; D012039:Regional Blood Flow; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000502:physiology; D017154:Stromal Cells
D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D016178:Granulocyte-Macrophage Colony-Stimulating Factor