RESUMO
Reconstituted high-density lipoprotein (rHDL) nanoparticles are excellent transporters of molecules and very useful for targeted therapy as they specifically recognize the scavenger receptor, class B1 (SR-B1) that is present on the surface of a wide range of tumor cells. However, they have rarely been employed to transport photosensitizers (PS) for photodynamic therapy (PDT). Rhodamine (R) compounds have been dismissed as useful PSs for PDT due to their low 1O2 production, excitation wavelengths with little tissue penetration, and poor selectivity for tumor cells. It was recently demonstrated that when irradiating at 532 nm or with Cerenkov radiation (CR) from a ß-emitting radionuclide, R123, R6G, and RB undergo electron transfer reactions (type I reaction) with folic acid. R6G also produces type I reactions with O2. In this work, the photodynamic effects of the rHDL-R system were evaluated in vitro. rHDL nanoparticles loaded with R123, R6G, and RB were synthesized, and the PS was internalized into T47D tumor cells. When cells were irradiated with a 532-nm laser in the presence of an rHDL-R systems, a cytotoxic photodynamic effect was obtained in the order R6G > R123 > RB. In the presence of CR from a 177Lu source, cytotoxicity showed the order R6G > RB > R123. The higher cytotoxicity induced by R6G in both cases corresponds to higher cellular internalization and larger production of type I and II reactions. Thus, in this work, it is proposed that rHDL-R/177Lu system can be applied in theragnostics as a multimodal radiotherapy-PDT-imaging system (imaging by SPECT or Cerenkov) and in hypoxic solid tumors in which external radiation is not effective and 177Lu-CR acts as light source.
Assuntos
Nanopartículas , Fotoquimioterapia , Linhagem Celular Tumoral , Humanos , Lipoproteínas HDL , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , RodaminasRESUMO
Despite the widespread use of nanotechnology in radio-imaging applications, lipoprotein based delivery systems have received only limited attention so far. These studies involve the synthesis of a novel hydrophobic radio-imaging tracer consisting of a hydrazinonicotinic acid (HYNIC)-N-dodecylamide and 99mTc conjugate that can be encapsulated into rHDL nanoparticles (NPs). These rHDL NPs can selectively target the Scavenger Receptor type B1 (SR-B1) that is overexpressed on most cancer cells due to excess demand for cholesterol for membrane biogenesis and thus can target tumors in vivo. We provide details of the tracer synthesis, characterization of the rHDL/tracer complex, in vitro uptake, stability studies and in vivo application of this new radio-imaging approach.
Assuntos
Lipoproteínas HDL/química , Nanopartículas/metabolismo , Ácidos Nicotínicos/química , Traçadores Radioativos , Cintilografia/métodos , Tecnécio/química , Animais , Sistemas de Liberação de Medicamentos , Humanos , Lipoproteínas HDL/administração & dosagem , Lipoproteínas HDL/metabolismo , Lipossomos/administração & dosagem , Lipossomos/química , Lipossomos/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Nus , Nanopartículas/administração & dosagem , Nanopartículas/química , Células PC-3 , Receptores Depuradores Classe B/metabolismo , Distribuição TecidualRESUMO
UNLABELLED: The α(ν)ß(3) integrin is over-expressed in the tumor neovasculature and the tumor cells of glioblastomas. The HIV Tat-derived peptide has been used to deliver various cargos into cells. The aim of this research was to synthesize and assess the in vitro and in vivo uptake of (99m)Tc-N2S2-Tat(49-57)-c(RGDyK) ((99m)Tc-Tat-RGD) in α(ν)ß(3) integrin positive cancer cells and compare it to that of a conventional (99m)Tc-RGD peptide ((99m)Tc-EDDA/HYNIC-E-[c(RGDfK)]2). METHODS: The c(RGDyK) peptide was conjugated to a maleimidopropionyl (MP) moiety through Lys, and the MP group was used as the branch position to form a thioether with the Cys(12) side chain of the Tat(49-57)-spacer-N2S2 peptide. (99m)Tc-Tat-RGD was prepared, and stability studies were carried out by size exclusion HPLC analyses in human serum. The in vitro affinity for α(v)ß(3) integrin was determined by a competitive binding assay. In vitro internalization was determined using glioblastoma C6 cells. Biodistribution studies were accomplished in athymic mice with C6 induced tumors that had blocked and unblocked receptors. Images were obtained using a micro-SPECT/CT. RESULTS: (99m)Tc-Tat-RGD was obtained with a radiochemical purity higher than 95%, as determined by radio-HPLC and ITLC-SG analyses. Protein binding was 15.7% for (99m)Tc-Tat-RGD and 5.6% for (99m)Tc-RGD. The IC50 values were 6.7 nM ((99m)Tc-Tat-RGD) and 4.6 nM ((99m)Tc-RGD). Internalization in C6 cells was higher in (99m)Tc-Tat-RGD (37.5%) than in (99m)Tc-RGD (10%). Biodistribution studies and in vivo micro-SPECT/CT images in mice showed higher tumor uptake for (99m)Tc-Tat-RGD (6.98% ± 1.34% ID/g at 3h) than that of (99m)Tc-RGD (3.72%±0.52% ID/g at 3h) with specific recognition for α(v)ß(3) integrins. CONCLUSIONS: Because of the significant cell internalization (Auger and internal conversion electrons) and specific recognition for α(v)ß(3) integrins, the hybrid (99m)Tc-N2S2-Tat(49-57)-c(RGDyK) radiopharmaceutical is potentially useful for the imaging and possible therapy of tumors expressing α(v)ß(3) integrins.
Assuntos
Desenho de Fármacos , Regulação Neoplásica da Expressão Gênica , Glioma/metabolismo , Integrina alfaVbeta3/metabolismo , Oligopeptídeos/química , Compostos de Organotecnécio , Fragmentos de Peptídeos/química , Produtos do Gene tat do Vírus da Imunodeficiência Humana/química , Animais , Transporte Biológico , Linhagem Celular Tumoral , Glioma/diagnóstico por imagem , Glioma/patologia , Humanos , Masculino , Camundongos , Imagem Multimodal , Compostos de Organotecnécio/química , Compostos de Organotecnécio/metabolismo , Compostos de Organotecnécio/farmacocinética , Cintilografia , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/metabolismo , Compostos Radiofarmacêuticos/farmacocinéticaRESUMO
Osteoarthritis is the most common type of arthropathy and after cardiovascular diseases is the most disabling disease in developing countries. The dosimetry for the clinical application of 153-samarium-hydroxymacroaggregates (¹5³Sm-HM) for radiation synovectomy (RSV) and palliative treatment for arthritic pain, as far as we know, has not been reported. The aim of this research was to estimate the radiation dose necessary for synovial ablation and pain palliation with minimum risk to the patient. ¹5³Sm-HM (370 MBq) was administered intra-articularly in a patient with severe knee pain and hindered motility. Regions of interest drawn on sequential, conjugated, anterior and posterior scintigraphy images were used to obtain the respective activity. The data was entered into a knee joint histological-geometric model designed with micrometric dimensions to represent the synovial cell layers. The Monte Carlo code was used to calculate the absorbed dose in each of the 12 model-cells representing the distance from the synovial liquid to the cartilage or bone. The absorbed dose in the synovial cavity was 114 Gy which is sufficient energy for RSV. The treated patient referred little pain and higher motility with no adverse reactions. ¹5³Sm-HM is a potentially valid radiopharmaceutical for RSV, which effectively palliates knee pain.