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Theranostics ; 11(16): 7755-7766, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34335962


Background: Myocardial infarction (MI) evokes an organized remodeling process characterized by the activation and transdifferentiation of quiescent cardiac fibroblasts to generate a stable collagen rich scar. Early fibroblast activation may be amenable to targeted therapy, but is challenging to identify in vivo. We aimed to non-invasively image active fibrosis by targeting the fibroblast activation protein (FAP) expressed by activated (myo)fibroblasts, using a novel positron emission tomography (PET) radioligand [68Ga]MHLL1 after acute MI. Methods: One-step chemical synthesis and manual as well as module-based radiolabeling yielded [68Ga]MHLL1. Binding characteristics were evaluated in murine and human FAP-transfected cells, and stability tested in human serum. Biodistribution in healthy animals was interrogated by dynamic PET imaging, and metabolites were measured in blood and urine. The temporal pattern of FAP expression was determined by serial PET imaging at 7 d and 21 d after coronary artery ligation in mice as percent injected dose per gram (%ID/g). PET measurements were validated by ex vivo autoradiography and immunostaining for FAP and inflammatory macrophages. Results: [68Ga]MHLL1 displayed specific uptake in murine and human FAP-positive cells (p = 0.0208). In healthy mice the tracer exhibited favorable imaging characteristics, with low blood pool retention and dominantly renal clearance. At 7 d after coronary artery ligation, [68Ga]MHLL1 uptake was elevated in the infarct relative to the non-infarcted remote myocardium (1.3 ± 0.3 vs. 1.0 ± 0.2 %ID/g, p < 0.001) which persisted to 21 d after MI (1.3 ± 0.4 vs. 1.1 ± 0.4 %ID/g, p = 0.013). Excess unlabeled compound blocked tracer accumulation in both infarct and non-infarct remote myocardium regions (p < 0.001). Autoradiography and histology confirmed the regional uptake of [68Ga]MHLL1 in the infarct and especially border zone regions, as identified by Masson trichrome collagen staining. Immunostaining further delineated persistent FAP expression at 7 d and 21 d post-MI in the border zone, consistent with tracer distribution in vivo. Conclusion: The simplified synthesis of [68Ga]MHLL1 bears promise for non-invasive characterization of fibroblast activation protein early in remodeling after MI.

Endopeptidases/metabolismo , Radioisótopos de Gálio/farmacologia , Proteínas de Membrana/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Animais , Autorradiografia/métodos , Linhagem Celular Tumoral , Endopeptidases/fisiologia , Fibroblastos/metabolismo , Fibrose/diagnóstico por imagem , Radioisótopos de Gálio/metabolismo , Humanos , Masculino , Proteínas de Membrana/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Imagem Molecular/métodos , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/fisiopatologia , Miocárdio/patologia , Distribuição Tecidual/fisiologia , Tomografia Computadorizada por Raios X/métodos
Appl Radiat Isot ; 68(6): 1060-5, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20137958


2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine were prepared from the corresponding iodo and bromo derivatives using the Cu(+)-assisted nucleophilic exchange. 4-[211At]-L-phenylalanine was additionally prepared by destannylation of the BOC-derivatized 4-tributylstannyl-L-phenylalanine. Radiochemical yields of 2-[211At]-L-phenylalanine and 4-[211At]-L-phenylalanine by nucleophilic exchange were 52-74% and 65-85%. Radiochemical yield of 4-[211At]-L-phenylalanine by electrophilic destannylation was 35-50%. HPLC sequence analysis showed that 2-[211At]-L-phenylalanine followed the halogen sequence (F

Astato , Neoplasias Encefálicas/metabolismo , Glioma/metabolismo , Marcação por Isótopo/métodos , Fenilalanina/análogos & derivados , Compostos Radiofarmacêuticos/metabolismo , Linhagem Celular Tumoral , Humanos , Fenilalanina/metabolismo
Eur J Nucl Med Mol Imaging ; 37(5): 851-61, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20107790


PURPOSE: Monoclonal anti-CD33 antibodies conjugated with toxic calicheamicin derivative (gemtuzumab ozogamicin, GO) are a novel therapy option for acute myeloid leukaemia (AML). Key prognostic factors for patients with AML are high CD33 expression on the leukaemic cells and the ability to overcome mechanisms of resistance to cytotoxic chemotherapies, including drug efflux or other mechanisms decreasing apoptosis. Alpha particle-emitting radionuclides overwhelm such anti-apoptotic mechanisms by producing numerous DNA double-stranded breaks (DSBs) accompanied by decreased DNA repair. METHODS: We labelled anti-CD33 antibodies with the alpha-emitter (211)At and compared survival of leukaemic HL-60 and K-562 cells treated with the (211)At-labelled antibodies, GO or unlabelled antibodies as controls. We also measured caspase-3/7 activity, DNA fragmentation and necrosis in HL-60 cells after treatment with the different antibodies or with free (211)At. RESULTS: The mean labelling ratio of (211)At-labelled antibodies was 1:1,090 +/- 364 (range: 1:738-1:1,722) in comparison to 2-3:1 for GO. Tumour cell binding of (211)At-anti-CD33 was high in the presence of abundant CD33 expression and could be specifically blocked by unlabelled anti-CD33. (211)At-anti-CD33 decreased survival significantly more than did GO at comparable dilution (1:1,000). No significant differences in induction of apoptosis or necrosis or DNA DSB or in decreased survival were observed after (211)At-anti-CD33 (1:1,090) versus GO (1:1) treatment. CONCLUSION: Our results suggest that (211)At is a promising, highly cytotoxic radioimmunotherapy in CD33-positive leukaemia and kills tumour cells more efficiently than does calicheamicin-conjugated antibody. Labelling techniques leading to higher chemical yield and specific activities must be developed to increase (211)At-anti-CD33 therapeutic effects.

Aminoglicosídeos/farmacologia , Anticorpos Monoclonais/farmacologia , Antígenos CD/imunologia , Antígenos de Diferenciação Mielomonocítica/imunologia , Astato/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Imunoconjugados/química , Imunoconjugados/farmacologia , Leucemia/patologia , Leucemia/terapia , Partículas alfa , Aminoglicosídeos/uso terapêutico , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais Humanizados , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Apoptose/efeitos dos fármacos , Astato/química , Caspases/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Dano ao DNA , Ativação Enzimática/efeitos dos fármacos , Gemtuzumab , Regulação Neoplásica da Expressão Gênica , Células HL-60 , Humanos , Imunoconjugados/imunologia , Imunoconjugados/metabolismo , Células K562 , Leucemia/genética , Leucemia/metabolismo , Necrose/tratamento farmacológico , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico , Fatores de Tempo
Neurol Res ; 30(5): 476-9, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18953738


OBJECTIVE: As a neuroprotective drug, cyclosporin A (CsA) has been subject of multiple experimental works in traumatic brain injury (TBI) research. It is well known that CsA inhibits calcium (Ca2+) induced mitochondrial permeability transition (mPT). The aim of this study was to investigate the influence of CsA on the alteration of Ca2+ homeostasis after experimental brain injury. METHODS: Sprague-Dawley male rats (n = 36) with a mean weight of 330 g (280-350 g) were general anesthetized with isofluran through gas mask. The anesthetized animals (n = 24) were subjected to a controlled cortical impact (CCI) over the left parietotemporal cortex using round-tip impounder with a 5 mm diameter at a velocity of approximately 3.7 m/s and a penetration depth of 2 mm. The sham group (n = 12) underwent anesthesia and craniotomy without CCI. In the CCI groups, CsA (n = 12) or vehicle (n = 12) was administered 15 minutes post-injury with a subsequent i.p. injection after 24 hours. Thirty-three hours after injury or sham craniotomy, 45calcium (45Ca) suspended in physiologic saline solution was injected in the left femoral vein. Five hours after isotope administration, animals were killed and the brain was quickly removed and placed in powdered dry ice. Coronal plane sections (20 microm thick) taken every 400 microm from the frontal cortex through the occipital cortex, were exposed to cyclotron films for 14 days at -18 degrees C. Relative optical density was utilized to provide a relative measure of 45Ca accumulation within seven different structures. RESULTS: The difference of 45Ca accumulation (measured by relative optical density) in the CsA group was greater by 30-70% in the following structures compared to vehicle treated traumatized animals: temporal cortex, CA1, anteromedial and posteromedial thalamus (p < 0.05). CONCLUSION: Post-traumatic 45Ca accumulation is modified under CsA. The crucial neuroprotective effect of CsA might be unrelated to a reduction of post-traumatic Ca2+ accumulation, especially with regard to the importance of Ca2+ as an intracellular messenger governing a large number of cellular functions.

Lesões Encefálicas , Encéfalo/metabolismo , Cálcio/metabolismo , Ciclosporina/uso terapêutico , Fármacos Neuroprotetores/uso terapêutico , Animais , Autorradiografia , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Lesões Encefálicas/tratamento farmacológico , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Radioisótopos de Cálcio/metabolismo , Modelos Animais de Doenças , Masculino , Ratos , Ratos Sprague-Dawley
J Pharm Pharm Sci ; 10(2): 277s-285s, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17718931


PURPOSE: The objective of this study was to determine and verify the stability of 211At-labelled antibodies under physiological conditions and their specific cell-binding capacity for selected epitopes, in order to evaluate the potential of 211At for alpha-radioimmunotherapy. METHODS: 211At was produced at the department's cyclotron and was linked via the intermediate 3-211At-succinimidyl-benzoate (SAB) to the antineoplastic antibodies rituximab, gemtuzumab and gemtuzumab ozogamicin. The stability of the labelled antibodies was determined in serum for 21 h. Cell-binding experiments on HL-60 and CI-1 cells included kinetic, saturation and competitive binding studies. For comparison the binding to antigen-negative cells was determined. The binding specificity and affinity and the IC50-values were evaluated. RESULTS: A consistent yield of 30% and a specific activity of 3 MBq/nmol was obtained. The stability of 211At-antibodies in murine serum exceeded 85% at 37 degrees C. Cell-binding to antigen-positive cells was >25%, while binding to antigen-negative cells did not exceed the unspecific binding and was smaller than 1%. IC50 values ranged between 2 and 11 nmol/L. CONCLUSIONS: A routine preparation of 211At-labelled antibodies was established and the stability of the 211At-labelled antibodies under physiologic conditions was verified. Apparently, labelling of antibodies with 211At by the method described does not compromise the affinity and specificity to the respective epitopes.

Anticorpos Monoclonais/química , Antineoplásicos/química , Astato , Radioimunoterapia/métodos , Aminoglicosídeos/administração & dosagem , Aminoglicosídeos/química , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais Humanizados , Anticorpos Monoclonais Murinos , Antineoplásicos/administração & dosagem , Ligação Competitiva , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Estabilidade de Medicamentos , Epitopos , Gemtuzumab , Células HL-60 , Humanos , Concentração Inibidora 50 , Camundongos , Rituximab
Clin Cancer Res ; 12(4): 1342-8, 2006 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-16489092


PURPOSE: The sodium/iodide symporter (NIS) gene is currently explored in several trials to eradicate experimental cancer with radiodine ((131)I) by its beta-emission. We recently characterized NIS-specific cellular uptake of an alternative halide, radioastatine ((211)At), which emits high-energy alpha-particles. The aim of this study was to investigate in vivo effects of the high linear energy transfer (LET) emitter (211)At on tumor growth and outcome in nude mice. EXPERIMENTAL DESIGN: We administered radioastatide in a fractionated therapy scheme to NMRI nude mice harboring rapidly growing solid tumors established from a papillary thyroid carcinoma cell line genetically modified to express NIS (K1-NIS). Animals were observed over 1 year. Tumor growth, body weight, blood counts, survival, and side effects were measured compared with control groups without therapy and/or lack of NIS expression. RESULTS: Within 3 months, radioastatide caused complete primary tumor eradication in all cases of K1-NIS tumor-bearing nude mice (n = 25) with no tumor recurrence during 1 year follow-up. Survival rates of the K1-NIS/(211)At group were 96% after 6 months and 60% after 1 year, in contrast to those of control groups (maximum survival 40 days). CONCLUSION: Our study indicates that (211)At represents a promising substrate for NIS-mediated therapy of various cancers either with endogenous or gene transfer-mediated NIS expression.

Astato/uso terapêutico , Neoplasias Experimentais/radioterapia , Simportadores/metabolismo , Animais , Astato/efeitos adversos , Astato/farmacocinética , Atrofia , Linhagem Celular Tumoral , Seguimentos , Expressão Gênica , Humanos , Fígado/patologia , Fígado/efeitos da radiação , Camundongos , Camundongos Endogâmicos , Camundongos Nus , Neoplasias Experimentais/diagnóstico por imagem , Neoplasias Experimentais/metabolismo , Cintilografia , Análise de Sobrevida , Simportadores/genética , Glândula Tireoide/patologia , Glândula Tireoide/efeitos da radiação , Fatores de Tempo , Distribuição Tecidual , Transfecção , Ensaios Antitumorais Modelo de Xenoenxerto/métodos