RESUMO
Cellular MRI, which visualizes magnetically labelled cells (cells*), is an active research field for in vivo cell therapy and tracking. The simultaneous relaxation rate measurements (R2 *, R2 , R1 ) are the basis of a quantitative cellular MRI method proposed here. U937 cells were labelled with Molday ION Rhodamine B, a bi-functional superparamagnetic and fluorescent nanoparticle (U937*). U937* viability and proliferation were not affected in vitro. In vitro relaxometry was performed in a cell concentration range of [2.5 × 104 -108 ] cells/mL. These measurements show the existence of complementary cell concentration intervals where these rates vary linearly. The juxtaposition of these intervals delineates a wide cell concentration range over which one of the relaxation rates in a voxel of an in vivo image can be converted into an absolute cell concentration. The linear regime was found at high concentrations for R1 in the range of [106 - 2 × 108 ] cells/mL, at intermediate concentrations for R2 in [2.5 × 105 - 5 × 107 ] cells/mL and at low concentrations for R2 * in [8 × 104 - 5 × 106 ] cells/mL. In vivo relaxometry was performed in a longitudinal study, with labelled U937 cells injected into a U87 glioma mouse model. Using in vitro data, maps of in vivo U937* concentrations were obtained by converting one of the in vivo relaxation rates to cell concentration maps. MRI results were compared with the corresponding optical images of the same brains, showing the usefulness of our method to accurately follow therapeutic cell biodistribution in a longitudinal study. Results also demonstrate that the method quantifies a large range of magnetically labelled cells*. Copyright © 2016 John Wiley & Sons, Ltd.
Assuntos
Transplante de Células , Imageamento por Ressonância Magnética/métodos , Animais , Encéfalo/patologia , Contagem de Células , Movimento Celular , Fluorescência , Glioma/patologia , Xenoenxertos , Humanos , Magnetismo , Camundongos , Células U937/transplanteAssuntos
Antineoplásicos/farmacologia , Clioquinol/farmacologia , Leucemia Experimental/tratamento farmacológico , Leucemia Mieloide Aguda/enzimologia , Mieloma Múltiplo/enzimologia , Proteínas de Neoplasias/antagonistas & inibidores , Inibidores de Proteases/farmacologia , Inibidores de Proteassoma , Animais , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Proteínas Arqueais/antagonistas & inibidores , Povo Asiático , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/enzimologia , Clioquinol/efeitos adversos , Clioquinol/uso terapêutico , Cobre/antagonistas & inibidores , Cobre/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Endopeptidases , Humanos , Japão , Células K562/efeitos dos fármacos , Células K562/enzimologia , Células K562/transplante , Leucemia Experimental/enzimologia , Leucemia Mieloide Aguda/patologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Mieloma Múltiplo/patologia , Doenças do Nervo Óptico/induzido quimicamente , Doenças do Nervo Óptico/etnologia , Inibidores de Proteases/efeitos adversos , Inibidores de Proteases/uso terapêutico , Complexo de Endopeptidases do Proteassoma , Doenças da Medula Espinal/induzido quimicamente , Doenças da Medula Espinal/etnologia , Células U937/efeitos dos fármacos , Células U937/enzimologia , Células U937/transplanteRESUMO
In addition to its primary role as growth factor, human growth hormone (hGH) can also participate in cell survival, as already documented by its protective effect on human monocytes or human promyelocytic leukaemia U937 cells exposed to a Fas-mediated cell death signal. However, despite similarities in the molecular events following Fas and TNF-alpha receptor engagement, we report that U937 cells, genetically engineered to constitutively produce hGH, were made more sensitive to TNF-alpha-induced apoptosis than parental cells. This was due to overproduction of the antioxidant glutathione, which decreased the nuclear factor (NF)-kappaB activity known to control the expression of survival genes. These findings were confirmed in vivo, in nude mice bearing U937 tumours coinjected with recombinant hGH and the NF-kappaB -inducing anticancer drug daunorubicin, to avoid the in vivo toxicity of TNF-alpha. This study therefore highlights one of the various properties of hGH that may have potential clinical implications.