Cinética de internalización del radiofármaco 99mTc-N2S2-TAT (49-57) Lys3-BN en linfocitos humanos empleando el ensayo cometa.

En México, el cáncer de mama representa la segunda causa de muerte en mujeres de 30 a 60 años, esto involucra un gran problema de salud pública. Por eso es importante contar con nuevas formas que nos permitan detectar el cáncer de mama en una etapa temprana. Una de las nuevas alternativas es por medio del uso de los radiofármacos de tercera generación, estos se emplean en medicina nuclear para obtener imágenes de blancos moleculares específicos y son únicos en su capacidad para detectar in vivo sitios bioquímicos, tales como receptores y enzimas.Introducción: Los receptores del péptido liberador de la gastrina (GRP-r) se sobreexpresan en cáncer de mama y próstata. La bombesina (BN) se une específica y fuertemente a GRP-r, esto es el fundamento para marcar la BN con radiación gamma. El TAT (49-57) es un péptido que penetra fácilmente la membrana celular por lo que, conjugado a diferentes proteínas, actúa como un “caballo de Troya” al aumentar la internalización de fármacos a la célula. El radiofármaco 99mTc-N2S2-TAT (49-57)-Lys3 -BN fue sintetizado con la finalidad de utilizarse en una etapa temprana de la carcinogénesis, para el diagnóstico y terapia del cáncer de mama. Objetivo: Determinar la internalización mediante el ensayo cometa del radiofármaco con y sin TAT, induciendo daño al DNA. Materiales y métodos: Se emplearon linfocitos humanos, con los siguientes protocolos: a) TATBN, b) 99mTc-Lys3 -BN; c) 99mTc-TAT (49-57)-Lys3 -BN y d) grupo control. Se realizó el ensayo cometa y se evaluó la cinética de internalización a 0, 5, 10, 15, 30 y 60 minutos en 3 repeticiones con cada uno, con actividades de 2.9, 6.6, 9.01 y 14.8 MBq. Se leyeron 100 células por tiempo y tratamiento, se determinó el Tail momento (TM). Se aplicó Kruscal-Wallis con p≤0.05 para la comparación entre los tratamientos. Resultados: El daño causado por el 99mTc-TAT-BN es mayor y diferente significativamente a los 30 minutos, respecto al control, mientras que 99mTc-BN y TAT-BN no los son. Conclusiones: Esto demuestra que el TAT-BN favorece la internalización del radiofármaco

Modelo para el cálculo de densidad ósea a partir de la matriz generada por imagen de rayos x

En la actualidad existen varios métodos para determinar la densidad ósea, la cual se define como la masa en relación con el volumen de la estructura ósea. Se ha demostrado que ésta es el factor predictivo más fuerte de riesgos de fractura, ya que sirve para el diagnóstico de algunas enfermedades como la osteoporosis. El presente trabajo propone un método complementario para determinar la densidad ósea con base en el coeficiente de atenuación de las regiones de interés y ayudar a un mejor diagnóstico clínico

Internal radiation dose assessment of radiopharmaceuticals prepared with cyclotron-produced 99m Tc

Technetium-99m (99m Tc) is the radioisotope most widely used in diagnostic nuclear medicine. It is readily available from 99 Mo/99m Tc generators as the \u3b2- decay product of the 99 Mo (T\ubd =66 h) parent nuclide. This latter is obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct reactions using proton beams on specific target materials [100 Mo(p,2n)99m Tc], have the potential to be both reliable and relatively cost-effective. However, results showed that the 99m Tc extracted from proton-bombarded 100 Mo-enriched targets contains small quantities of several Tc radioisotopes (93m Tc, 93 Tc, 94 Tc, 94m Tc, 95 Tc, 95m Tc 96 Tc and 97m Tc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotron-produced 99m Tc (CP-99m Tc) using 99.05% 100 Mo-enriched metallic targets

Antibacterial efficacy of gold and silver nanoparticles functionalized with the ubiquicidin (29–41) antimicrobial peptide

Recent studies have demonstrated that drug antimicrobial activity is enhanced when metallic nanoparticles are used as an inorganic support, obtaining synergic effects against microorganisms. The cationic antimicrobial peptide ubiquicidin 29–41 (UBI) has demonstrated high affinity and sensitivity towards fungal and bacterial infections. The aim of this research was to prepare and evaluate the antimicrobial efficacy of engineered multivalent nanoparticle systems based on silver or gold nanoparticles functionalized with UBI. Spectroscopy techniques demonstrated that NPs were functionalized with UBI mainly through interactions with the -NH2 groups. A significant increase in the antibacterial activity against Escherichia coli and Pseudomonas aeruginosawas obtainedwith the conjugateAgNP-UBI with regard to that of AgNP. No inhibitionof bacterial growth was observed with AuNP and AuNP-UBI using a nanoparticle concentration of up to 182 gmL−1.Nonetheless, silver nanoparticles conjugated to the UBI antimicrobial peptide may provide an alternative therapy for topical infections.This work was supported by the PROMEP-CA-68 (2013) project and The International Atomic Energy Agency (Contract no. 18358)

Synthesis and Evaluation of 177Lu-DOTA-DN(PTX)-BN for Selective and Concomitant Radio and Drug—Therapeutic E ect on Breast Cancer Cells

The peptide-receptor radionuclide therapy (PRRT) is a successful approach for selectively delivering radiation within tumor sites through specific recognition of radiolabeled peptides by overexpressed receptors on cancer cell surfaces. The e cacy of PRRT could be improved by using polymeric radio- and drug- therapy nanoparticles for a concomitant therapeutic e ect on malignant cells. This research aimed to prepare and evaluate, a novel drug and radiation delivery nanosystem based on the 177Lu-labeled polyamidoamine (PAMAM) dendrimer (DN) loaded with paclitaxel (PTX) and functionalized on the surface with the Lys1Lys3(DOTA)-bombesin (BN) peptide for specific targeting to gastrin-releasing peptide receptors (GRPr) overexpressed on breast cancer cells. DN was first conjugated covalently to BN and DOTA (chemical moiety for lutetium-177 complexing) and subsequently loaded with PTX. The characterization by microscopic and spectroscopic techniques, in-vitro drug delivery tests as well as in in-vitro and in-vivo cellular uptake of 177Lu-DOTA-DN(PTX)-BN by T47D breast cancer cells (GRPr-positive), indicated the formation of an improved delivery nanosystem with target-specific recognition by GRPr. Results of the 177Lu-DOTA-DN(PTX)-BN e ect on T47D cell viability (1.3%, compared with 10.9% of 177Lu-DOTA-DN-BN and 14.0% of DOTA-DN-(PTX)-BN) demonstrated the concomitant radiotherapeutic and chemotherapeutic properties of the polymeric nanosystem as a potential agent for the treatment of GRPr-positive tumors.This study was supported by the grant CONACyT-CB-A1S38087 and the International Atomic Energy Agency (CRP-F2264). It was performed as part of the activities of the “Laboratorio Nacional de Investigación y Desarrollo de Radiofármacos, CONACyT”

Development of 177Lu-scFvD2B as a Potential Immunotheranostic Agent for Tumors Overexpressing the Prostate Specific Membrane Antigen

The clinical translation of theranostic 177Lu-radiopharmaceuticals based on inhibitors of the prostate-specific membrane antigen (PSMA) has demonstrated positive clinical responses in patients with advanced prostate cancer (PCa). However, challenges still remain, particularly regarding their pharmacokinetic and dosimetric properties. We developed a potential PSMA-immunotheranostic agent by conjugation of a single-chain variable fragment of the IgGD2B antibody (scFvD2B) to DOTA, to obtain a 177Lu-labelled agent with a better pharmacokinetic profile than those previously reported. The labelled conjugated 177Lu-scFvD2B was obtained in high yield and stability. In vitro, 177Lu-scFvD2B disclosed a higher binding and internalization in LNCaP (PSMA-positive) compared to PC3 (negative control) human PCa cells. In vivo studies in healthy nude mice revealed that 177Lu-scFvD2B present a favorable biokinetic profile, characterized by a rapid clearance from non-target tissues and minimal liver accumulation, but a slow wash-out from kidney. Micro-SPECT/CT imaging of mice bearing pulmonary microtumors evidenced a slow uptake by LNCaP tumors, which steadily rose up to a maximum value of 3.6 SUV at 192 h. This high and prolonged tumor uptake suggests that 177Lu-scFvD2B has great potential in delivering ablative radiation doses to PSMA-expressing tumors, and warrants further studies to evaluate its preclinical therapeutic efficacy

Engineered rHDL Nanoparticles as a Suitable Platform for Theranostic Applications

Reconstituted high-density lipoproteins (rHDLs) can transport and specifically release drugs and imaging agents, mediated by the Scavenger Receptor Type B1 (SR-B1) present in a wide variety of tumor cells, providing convenient platforms for developing theranostic systems. Usually, phospholipids or Apo-A1 lipoproteins on the particle surfaces are the motifs used to conjugate molecules for the multifunctional purposes of the rHDL nanoparticles. Cholesterol has been less addressed as a region to bind molecules or functional groups to the rHDL surface. To maximize the efficacy and improve the radiolabeling of rHDL theranostic systems, we synthesized compounds with bifunctional agents covalently linked to cholesterol. This strategy means that the radionuclide was bound to the surface, while the therapeutic agent was encapsulated in the lipophilic core. In this research, HYNIC-S-(CH2)3-S-Cholesterol and DOTA-benzene-p-SC-NH-(CH2)2-NH-Cholesterol derivatives were synthesized to prepare nanoparticles (NPs) of HYNIC-rHDL and DOTA-rHDL, which can subsequently be linked to radionuclides for SPECT/PET imaging or targeted radiotherapy. HYNIC is used to complexing 99mTc and DOTA for labeling molecules with 111, 113mIn, 67, 68Ga, 177Lu, 161Tb, 225Ac, and 64Cu, among others. In vitro studies showed that the NPs of HYNIC-rHDL and DOTA-rHDL maintain specific recognition by SR-B1 and the ability to internalize and release, in the cytosol of cancer cells, the molecules carried in their core. The biodistribution in mice showed a similar behavior between rHDL (without surface modification) and HYNIC-rHDL, while DOTArHDL exhibited a different biodistribution pattern due to the significant reduction in the lipophilicity of the modified cholesterol molecule. Both systems demonstrated characteristics for the development of suitable theranostic platforms for personalized cancer treatment.Consejo Nacional de Ciencia y Tecnología (CONACyT, Mexico), through Grant SEP-CONACyT-CB-2016-01-287217. the financing program for female scientists EDOMEX, Grant Number FICDTEM-2021-015

177Lu-Dendrimer conjugated to folate and bombesin with gold nanoparticles in the dendritic cavity: A potential theranostic radiopharmaceutical

177Lu-labeled nanoparticles conjugated to biomolecules have been proposed as a new class of theranostic radiopharmaceuticals. The aim of this research was to synthesize 177Lu-dendrimer(PAMAM-G4)-folate-bombesin with gold nanoparticles (AuNPs) in the dendritic cavity and to evaluate the radiopharmaceutical potential for targeted radiotherapy and the simultaneous detection of folate receptors (FRs) and gastrin-releasing peptide receptors (GRPRs) overexpressed in breast cancer cells. p-SCN-Benzyl-DOTA was conjugated in aqueous-basic medium to the dendrimer.The carboxylate groups of Lys1Lys3(DOTA)-bombesin and folic acid were activatedwithHATUand also conjugated to the dendrimer.The conjugate was mixed with 1%HAuCl4 followed by the addition of NaBH4 and purified by ultrafiltration. Elemental analysis (EDS), particle size distribution (DLS), TEM analysis, UV-Vis, and infrared and fluorescence spectroscopies were performed. The conjugate was radiolabeled using 177LuCl3 or 68GaCl3 and analyzed by radio-HPLC. Studies confirmed the dendrimer functionalization with high radiochemical purity (>95%). Fluorescence results demonstrated that the presence ofAuNPs in the dendritic cavity confers useful photophysical properties to the radiopharmaceutical for optical imaging. Preliminary binding studies in T47D breast cancer cells showed a specific cell uptake (41.15 ± 2.72%). 177Ludendrimer( AuNP)-folate-bombesin may be useful as an optical and nuclear imaging agent for breast tumors overexpressing GRPR and FRs, as well as for targeted radiotherapy.CONACYT-SEP-CB-2014-01-242443 International Atomic Energy Agency (Grant 18358) LaboratorioNacional de Investigaci´on yDesarrollo de Radiof´armacos, CONACy

Fluorescent, Plasmonic, and Radiotherapeutic Properties of the 177Lu–Dendrimer-AuNP–Folate–Bombesin Nanoprobe Located Inside Cancer Cells

The integration of fluorescence and plasmonic properties into one molecule is of importance in developing multifunctional imaging and therapy nanoprobes. The aim of this research was to evaluate the fluorescent properties and the plasmonic–photothermal, therapeutic, and radiotherapeutic potential of 177Lu–dendrimer conjugated to folate and bombesin with gold nanoparticles in the dendritic cavity (177Lu–DenAuNP–folate–bombesin) when it is internalized in T47D breast cancer cells. The intense near-Infrared (NIR) fluorescence emitted at 825 nm from the conjugate inside cells corroborated the usefulness of DenAuNP–folate–bombesin for optical imaging. After laser irradiation, the presence of the nanosystem in cells caused a significant increase in the temperature of the medium (46.8oC, compared to 39.1oC without DenAuNP–folate–bombesin, P < 0.05), resulting in a significant decrease in cell viability (down to 16.51% + 1.52%) due to the 177Lu–DenAuNP–folate–bombesin plasmonic properties. After treatment with 177Lu–DenAuNP–folate–bombesin, the T47D cell viability decreased 90% because of the radiation-absorbed dose (63.16 + 4.20 Gy) delivered inside the cells. The 177Lu–DenAuNP–folate–bombesin nanoprobe internalized in cancer cells exhibited properties suitable for optical imaging, plasmonic–photothermal therapy, and targeted radiotherapy.CONACYT-SEP-CB-2014-01-24244