Article révisé par les pairs
Résumé : Cell therapy-induced changes in the perfusion of areas of myocardial infarction (MI) remain unclear. This study investigated whether an original pinhole SPECT technique could be applied to a rat MI model to analyze local improvement in myocardial perfusion relating to engraftment sites of bone marrow-derived stem cells (BMSCs). Methods: Four-month-old MI rats were either untreated (n = 8) or treated (n = 10) by intramyocardial injection of 111In-labeled BMSCs. Early distribution of 111In-BMSCs within the MI target was evidenced by dual 111In/99mTc pinhole SPECT 48 h later. Myocardial perfusion was serially monitored by 99mTc- sestamibi pinhole gated SPECT up to 3 mo after transplantation. Results: Forty-eight hours after transplantation, 111In-BMSCs were observed in all treated rats and in 18 of their 32 underperfused MI segments (<70% sestamibi uptake before transplantation). During the subsequent 3-mo follow-up, the perfusion of MI segments worsened in untreated rats (absolute change in sestamibi uptake, -3% ± 3%; P < 0.05) but improved in treated rats (+4% ± 7%; P < 0.05). This perfusion improvement was unrelated to the initial detection of 111In-BMSCs (+2% ± 6% in segments with 111In-BMSCs vs. +5% ± 7% in those without; not statistically significant) but was strongly associated with less severe perfusion defects before transplantation (+6% ± 6% in segments with 60%-70% sestamibi uptake [n 5 19] vs. 21% 6 6% in those with <60% uptake [n = 13]; P = 0.003). Conclusion: When BMSCs are injected within chronic MI, perfusion enhancement predominates in the MI areas showing a high enough residual perfusion before treatment but not in those of the initial cell engraftment, giving evidence of dependency on the perfusion and metabolic environment at implantation sites. Copyright © 2007 by the Society of Nuclear Medicine, Inc.

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