Constitutive human telomerase reverse transcriptase expression enhances regenerative properties of endothelial progenitor cells.
BACKGROUND
The regulatory molecule for cell life span, telomerase, was modified by human telomerase reverse transcriptase (hTERT) gene transfer to investigate its effect on regenerative properties of endothelial progenitor cells (EPCs) in neovascularization.


RESULTS
Telomerase activity was enhanced in hTERT-transduced EPCs (Td-TERTs) (1.2-fold versus no transduced EPCs [no-Td] and 1.2-fold versus GFP-transduced EPCs [Td/GFPs] at day 8; 5.2-fold versus no-Td and 4.8-fold versus Td/GFP at day 21, respectively) Mitogenic capacity in Td/TERTs exceeded that in Td/GFPs at day 8 (0.62+/-0.02 versus 0.53+/-0.01, respectively; P<0.01). Vascular endothelial growth factor-induced cell migration in EPCs was markedly enhanced by hTERT overexpression (Td/TERTs versus Td/GFPs, 292+/-12 versus 174+/-6 cells, respectively; P<0.01). hTERT overexpression has rescued EPCs from starvation-induced cell apoptosis, an outcome that was further enhanced in response to vascular endothelial growth factor. The colony appearance of totally differentiated endothelial cells (tdECs) was detected before day 30 only in Td/TERT, whereas no tdEC colonies could be detected in both Td/GFPs and no-Tds. Finally, we investigated in vivo transplantation of heterologous EPCs. Td/TERTs dramatically improved postnatal neovascularization in terms of limb salvage by 4-fold in comparison with that of Td/GFPs; limb perfusion was measured by laser Doppler (0.77+/-0.10 versus 0.47+/-0.06; P=0.02), and capillary density (224+/-78 versus 90+/-40 capillaries/mm2; P<0.01).


CONCLUSIONS
These findings provide the novel evidence that telomerase activity contributes to EPC angiogenic properties; mitogenic activity, migratory activity, and cell survival. This enhanced regenerative activity of EPCs by hTERT transfer will provide novel therapeutical strategy for postnatal neovascularization in severe ischemic disease patients.
Department of Medicine (Vascular Medicine, Cardiology, Cardiovascular Research), St Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Mass 02135, USA.
Satoshi
S
Murasawa
Joan
J
Llevadot
Marcy
M
Silver
Jeffrey M
JM
Isner
Douglas W
DW
Losordo
Takayuki
T
Asahara
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology; D004268:DNA-Binding Proteins; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D015870:Gene Expression; D006614:Hindlimb / Q000098:blood supply / Q000503:physiopathology; D006801:Humans; D007511:Ischemia / Q000503:physiopathology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D012038:Regeneration / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D019098:Telomerase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D014161:Transduction, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
D004268:DNA-Binding Proteins; C509186:TERT protein, human; D019098:Telomerase; C509187:Tert protein, mouse; D001616:beta-Galactosidase