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1.
J Nucl Med ; 54(3): 447-54, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23353687

RESUMO

UNLABELLED: Because of their extended differentiation capacity, stem cells have gained great interest in the field of regenerative medicine. For the development of therapeutic strategies, more knowledge on the in vivo fate of these cells has to be acquired. Therefore, stem cells can be labeled with radioactive tracer molecules such as (18)F-FDG, a positron-emitting glucose analog that is taken up and metabolically trapped by the cells. The aim of this study was to optimize the radioactive labeling of mesenchymal stem cells (MSCs) and multipotent adult progenitor cells (MAPCs) in vitro with (18)F-FDG and to investigate the potential radiotoxic effects of this labeling procedure with a range of techniques, including transmission electron microscopy (TEM). METHODS: Mouse MSCs and rat MAPCs were used for (18)F-FDG uptake kinetics and tracer retention studies. Cell metabolic activity, proliferation, differentiation and ultrastructural changes after labeling were evaluated using an Alamar Blue reagent, doubling time calculations and quantitative TEM, respectively. Additionally, mice were injected with MSCs and MAPCs prelabeled with (18)F-FDG, and stem cell biodistribution was investigated using small-animal PET. RESULTS: The optimal incubation period for (18)F-FDG uptake was 60 min. Significant early tracer washout was observed, with approximately 30%-40% of the tracer being retained inside the cells 3 h after labeling. Cell viability, proliferation, and differentiation capacity were not severely affected by (18)F-FDG labeling. No major changes at the ultrastructural level, considering mitochondrial length, lysosome size, the number of lysosomes, the number of vacuoles, and the average rough endoplasmic reticulum width, were observed with TEM. Small-animal PET experiments with radiolabeled MAPCs and MSCs injected intravenously in mice showed a predominant accumulation in the lungs and a substantial elution of (18)F-FDG from the cells. CONCLUSION: MSCs and MAPCs can be successfully labeled with (18)F-FDG for molecular imaging purposes. The main cellular properties are not rigorously affected. TEM confirmed that the cells' ultrastructural properties are not influenced by (18)F-FDG labeling. Small-animal PET studies confirmed the intracellular location of the tracer and the possibility of imaging injected prelabeled stem cell types in vivo. Therefore, direct labeling of MSCs and MAPCs with (18)F-FDG is a suitable technique to noninvasively assess cell delivery and early retention with PET.


Assuntos
Células-Tronco Adultas/diagnóstico por imagem , Fluordesoxiglucose F18 , Células-Tronco Mesenquimais/diagnóstico por imagem , Células-Tronco Multipotentes/diagnóstico por imagem , Células-Tronco Adultas/metabolismo , Células-Tronco Adultas/ultraestrutura , Animais , Diferenciação Celular , Células Cultivadas , Radioisótopos de Flúor , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/ultraestrutura , Camundongos , Microscopia Eletrônica de Transmissão , Células-Tronco Multipotentes/metabolismo , Células-Tronco Multipotentes/ultraestrutura , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Ratos , Medicina Regenerativa , Engenharia Tecidual
2.
Circulation ; 127(6): 710-9, 2013 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-23307829

RESUMO

BACKGROUND: Stem cells are thought to enhance vascular remodeling in ischemic tissue in part through paracrine effects. Using molecular imaging, we tested the hypothesis that treatment of limb ischemia with multipotential adult progenitor cells (MAPCs) promotes recovery of blood flow through the recruitment of proangiogenic monocytes. METHODS AND RESULTS: Hind-limb ischemia was produced in mice by iliac artery ligation, and MAPCs were administered intramuscularly on day 1. Optical imaging of luciferase-transfected MAPCs indicated that cells survived for 1 week. Contrast-enhanced ultrasound on days 3, 7, and 21 showed a more complete recovery of blood flow and greater expansion of microvascular blood volume in MAPC-treated mice than in controls. Fluorescent microangiography demonstrated more complete distribution of flow to microvascular units in MAPC-treated mice. On ultrasound molecular imaging, expression of endothelial P-selectin and intravascular recruitment of CX(3)CR-1-positive monocytes were significantly higher in MAPC-treated mice than in the control groups at days 3 and 7 after arterial ligation. Muscle immunohistology showed a >10-fold-greater infiltration of monocytes in MAPC-treated than control-treated ischemic limbs at all time points. Intravital microscopy of ischemic or tumor necrosis factor-α-treated cremaster muscle demonstrated that MAPCs migrate to perimicrovascular locations and potentiate selectin-dependent leukocyte rolling. In vitro migration of human CD14(+) monocytes was 10-fold greater in response to MAPC-conditioned than basal media. CONCLUSIONS: In limb ischemia, MAPCs stimulate the recruitment of proangiogenic monocytes through endothelial activation and enhanced chemotaxis. These responses are sustained beyond the MAPC lifespan, suggesting that paracrine effects promote flow recovery by rebalancing the immune response toward a more regenerative phenotype.


Assuntos
Extremidades/irrigação sanguínea , Isquemia/terapia , Imagem Molecular , Neovascularização Fisiológica/fisiologia , Comunicação Parácrina/fisiologia , Transplante de Células-Tronco , Células-Tronco Adultas/diagnóstico por imagem , Células-Tronco Adultas/efeitos dos fármacos , Células-Tronco Adultas/transplante , Animais , Receptor 1 de Quimiocina CX3C , Movimento Celular/fisiologia , Extremidades/diagnóstico por imagem , Extremidades/patologia , Humanos , Artéria Ilíaca/diagnóstico por imagem , Artéria Ilíaca/efeitos dos fármacos , Artéria Ilíaca/fisiopatologia , Isquemia/diagnóstico por imagem , Isquemia/patologia , Receptores de Lipopolissacarídeos/análise , Camundongos , Camundongos Endogâmicos C57BL , Microvasos/diagnóstico por imagem , Microvasos/efeitos dos fármacos , Microvasos/patologia , Microvasos/fisiopatologia , Monócitos/patologia , Monócitos/fisiologia , Células-Tronco Multipotentes/diagnóstico por imagem , Células-Tronco Multipotentes/efeitos dos fármacos , Células-Tronco Multipotentes/transplante , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/patologia , Neovascularização Fisiológica/efeitos dos fármacos , Selectina-P/biossíntese , Comunicação Parácrina/efeitos dos fármacos , Receptores de Quimiocinas/análise , Transplante Heterólogo , Fator de Necrose Tumoral alfa/farmacologia , Ultrassonografia
3.
J Orthop Res ; 27(3): 295-302, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18752273

RESUMO

Adult stem cells are promising therapeutic reagents for skeletal regeneration. We hope to validate by molecular imaging technologies the in vivo life cycle of adipose-derived multipotent cells (ADMCs) in an animal model of skeletal injury. Primary ADMCs were lentivirally transfected with a fusion reporter gene and injected intravenously into mice with bone injury or sham operation. Bioluminescence imaging (BLI), [(18)F]FHBG (9-(fluoro-hydroxy-methyl-butyl-guanine)-micro-PET, [(18)F]Fluoride ion micro-PET and micro-CT were performed to monitor stem cells and their effect. Bioluminescence microscopy and immunohistochemistry were done for histological confirmation. BLI showed ADMC's traffic from the lungs then to the injury site. BLI microscopy and immunohistochemistry confirmed the ADMCs in the bone defect. Micro-CT measurements showed increased bone healing in the cell-injected group compared to the noninjected group at postoperative day 7 (p < 0.05). Systemically administered ADMC's traffic to the site of skeletal injury and facilitate bone healing, as demonstrated by molecular and small animal imaging. Molecular imaging technologies can validate the usage of adult adipose tissue-derived multipotent cells to promote fracture healing. Imaging can in the future help establish therapeutic strategies including dosage and administration route.


Assuntos
Regeneração Óssea , Fraturas do Fêmur/terapia , Consolidação da Fratura , Transplante de Células-Tronco Mesenquimais , Células-Tronco Multipotentes/transplante , Tecido Adiposo/citologia , Células-Tronco Adultas/diagnóstico por imagem , Células-Tronco Adultas/fisiologia , Células-Tronco Adultas/transplante , Animais , Feminino , Fraturas do Fêmur/diagnóstico por imagem , Radioisótopos de Flúor , Genes Reporter , Luciferases de Vaga-Lume , Proteínas Luminescentes , Camundongos , Células-Tronco Multipotentes/diagnóstico por imagem , Células-Tronco Multipotentes/fisiologia , Tomografia por Emissão de Pósitrons , Microtomografia por Raio-X , Proteína Vermelha Fluorescente
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