RESUMEN
BACKGROUND: Recent results from animal studies suggest that stem cells may be able to home to sites of myocardial injury to assist in tissue regeneration. However, the histological interpretation of postmortem tissue, on which many of these studies are based, has recently been widely debated. METHODS AND RESULTS: With the use of the high sensitivity of a combined single-photon emission CT (SPECT)/CT scanner, the in vivo trafficking of allogeneic mesenchymal stem cells (MSCs) colabeled with a radiotracer and MR contrast agent to acute myocardial infarction was dynamically determined. Redistribution of the labeled MSCs after intravenous injection from initial localization in the lungs to nontarget organs such as the liver, kidney, and spleen was observed within 24 to 48 hours after injection. Focal and diffuse uptake of MSCs in the infarcted myocardium was already visible in SPECT/CT images in the first 24 hours after injection and persisted until 7 days after injection and was validated by tissue counts of radioactivity. In contrast, MRI was unable to demonstrate targeted cardiac localization of MSCs in part because of the lower sensitivity of MRI. CONCLUSIONS: Noninvasive radionuclide imaging is well suited to dynamically track the biodistribution and trafficking of mesenchymal stem cells to both target and nontarget organs.
Asunto(s)
Trasplante de Células Madre Mesenquimatosas , Infarto del Miocardio/diagnóstico por imagen , Infarto del Miocardio/terapia , Células Madre/diagnóstico por imagen , Tomografía Computarizada de Emisión de Fotón Único/métodos , Animales , Diferenciación Celular , División Celular , Supervivencia Celular , Perros , Radioisótopos de Indio , Inyecciones Intravenosas , Imagen por Resonancia Magnética , Trasplante de Células Madre Mesenquimatosas/efectos adversos , Compuestos Organometálicos , Oxiquinolina/análogos & derivados , Reproducibilidad de los Resultados , Tomografía Computarizada de Emisión de Fotón Único/normas , Tomografía Computarizada por Rayos X , Trasplante HomólogoAsunto(s)
Imagen por Resonancia Magnética/métodos , Células Madre Mesenquimatosas/química , Infarto del Miocardio/terapia , Animales , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Condrogénesis/efectos de los fármacos , Medios de Contraste/farmacocinética , Medios de Contraste/toxicidad , Dextranos , Perros , Óxido Ferrosoférrico , Humanos , Hierro/farmacocinética , Hierro/toxicidad , Nanopartículas de Magnetita , Células Madre Mesenquimatosas/efectos de los fármacos , Infarto del Miocardio/patología , Óxidos/farmacocinética , Óxidos/toxicidad , Polilisina/farmacología , Coloración y Etiquetado/métodos , PorcinosRESUMEN
A technique for fast imaging of regional myocardial function using a spiral acquisition in combination with strain-encoded (SENC) magnetic resonance imaging (MRI) is presented in this paper. This technique, which is termed fast-SENC, enables scan durations as short as a single heartbeat. A reduced field of view (FOV) without foldover artifacts was achieved by localized SENC, which selectively excited the region around the heart. The two images required for SENC imaging (low- and high-tuning) were acquired in an interleaved fashion throughout the cardiac cycle to further shorten the scan time. Regional circumferential contraction and longitudinal shortening of both the left ventricle (LV) and right ventricle (RV) were examined in long- and short-axis views, respectively. The in vivo results obtained from five human subjects and five infarcted dogs are presented. The results of the fast-SENC technique in a single heartbeat acquisition were comparable to those obtained by conventional SENC in a long acquisition time. Therefore, fast-SENC may prove useful for imaging during stress or arrhythmia.