RESUMO
PURPOSE: Synchrotron microbeam radiation therapy (MRT), based on an inhomogeneous geometric and microscopic irradiation pattern of the tissues with high-dose and high-dose-rate x-rays, enhances the permeability of brain tumor vessels. This study attempted to determine the time and size range of the permeability window induced by MRT in the blood-brain (tumor) barrier. METHODS AND MATERIALS: Rats-bearing 9L gliomas were exposed to MRT, either unidirectional (tumor dose, 406 Gy) or bidirectional (crossfired) (2 × 203 Gy). We measured vessel permeability to molecules of 3 sizes (Gd-DOTA, Dotarem, 0.56 kDa; gadolinium-labeled albumin, â¼74 kDa; and gadolinium-labeled IgG, 160 kDa) by daily in vivo magnetic resonance imaging, from 1 day before to 10 days after irradiation. RESULTS: An equivalent tumor dose of bidirectional MRT delivered from 2 orthogonal directions increased tumor vessel permeability for the smallest molecule tested more effectively than unidirectional MRT. Bidirectional MRT also affected the permeability of normal contralateral vessels to a different extent than unidirectional MRT. Conversely, bidirectional MRT did not modify the permeability of normal or tumor vessels for both larger molecules (74 and 160 kDa). CONCLUSIONS: High-dose bidirectional (cross-fired) MRT induced a significant increase in tumor vessel permeability for small molecules between the first and the seventh day after irradiation, whereas permeability of vessels in normal brain tissue remained stable. Such a permeability window could facilitate an efficient and safe delivery of intravenous small molecules (≤0.56 kDa) to tumoral tissues. A permeability window was not achieved by molecules larger than gado-grafted albumin (74 kDa). Vascular permeability for molecules between these 2 sizes has not been determined.
Assuntos
Barreira Hematoencefálica , Neoplasias Encefálicas , Permeabilidade Capilar , Meios de Contraste , Imageamento por Ressonância Magnética , Compostos Organometálicos , Ratos Endogâmicos F344 , Síncrotrons , Animais , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/irrigação sanguínea , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Permeabilidade Capilar/efeitos da radiação , Ratos , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/efeitos da radiação , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/farmacocinética , Meios de Contraste/farmacocinética , Gadolínio/farmacocinética , Fatores de Tempo , Masculino , Imunoglobulina G , Albuminas/metabolismo , Albuminas/farmacocinética , Glioma/radioterapia , Glioma/irrigação sanguínea , Glioma/metabolismo , Glioma/diagnóstico por imagem , Glioma/patologia , Dosagem Radioterapêutica , Compostos HeterocíclicosRESUMO
Ultrasound and microbubbles, an ultrasound contrast agent, have recently increased attention to developing novel drug delivery systems. Ultrasound exposure can induce mechanical effects derived from microbubbles behaviors such as an expansion, contraction, and collapse depending on ultrasound conditions. These mechanical effects induce several biological effects, including enhancement of vascular permeability. For drug delivery, one promising approach is enhancing vascular permeability using ultrasound and microbubbles, resulting in improved drug transport to targeted tissues. This approach is applied to several tissues and drugs to cure diseases. This review describes the enhancement of vascular permeability by ultrasound and microbubbles and its therapeutic application, including our recent study. We also discuss the current situation of the field and its potential future perspectives.
Assuntos
Antineoplásicos/administração & dosagem , Fármacos do Sistema Nervoso Central/administração & dosagem , Meios de Contraste/farmacologia , Sistemas de Liberação de Medicamentos/métodos , Microbolhas , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/efeitos da radiação , Permeabilidade Capilar/efeitos dos fármacos , Permeabilidade Capilar/efeitos da radiação , Permeabilidade da Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos da radiação , Doenças do Sistema Nervoso Central/tratamento farmacológico , Doenças do Sistema Nervoso Central/patologia , Humanos , Neoplasias/irrigação sanguínea , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Ultrassonografia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The present study aimed to identify the mechanisms underlying the increase in vascular permeability in mouse skin following irradiation. The left ears of C3H mice were subjected to 2 and 15 Gy of radiation in a single exposure. At 24 h after irradiation, the ears were excised and tissue sections were stained with toluidine blue to assess mast cell degranulation. Vascular endothelial growth factor (VEGF) expression was assessed via immunohistochemistry and western blotting. Approximately 5% (3%-14%) (mean [95% CI]) of mast cells in the skin of control mice were degranulated; moreover, at 24 h after 2 Gy irradiation, this value increased to approximately 20% (17%-28%). Mast cell degranulation by 15 Gy irradiation (32% [24%-40%]) was greater than that by 2 Gy irradiation. Significant differences were observed in mast cell degranulation among the control, 2 Gy and 15 Gy groups (p = 0.012). Furthermore, VEGF-positive reactions were observed in the cytoplasm of scattered fibroblasts in the dermis. In immunohistochemistry tests, VEGF expression at 24 h after irradiation increased slightly in the 2 Gy group compared to that in the control group, whereas no difference in VEGF expression was observed in the 15 Gy group compared to that in the control group. Expression of VEGF in western blots was consistent with that in immunohistochemistry. In conclusion, mast cell degranulation was increased in mouse skin at 24 h after irradiation in a dose-dependent manner. In contrast, VEGF expression was slightly increased following only low-dose (2 Gy) irradiation.
Assuntos
Permeabilidade Capilar/efeitos da radiação , Degranulação Celular/efeitos da radiação , Mastócitos/efeitos da radiação , Pele/efeitos da radiação , Fator A de Crescimento do Endotélio Vascular/biossíntese , Animais , Relação Dose-Resposta à Radiação , Orelha Externa/citologia , Orelha Externa/efeitos da radiação , Regulação da Expressão Gênica/efeitos da radiação , Masculino , Mastócitos/fisiologia , Camundongos , Camundongos Endogâmicos C3H , Pele/citologia , Fator A de Crescimento do Endotélio Vascular/genéticaRESUMO
BACKGROUND: At present, gamma knife radiosurgery plays an important role in neurosurgical procedures. Gamma knife radiosurgery has been used to treat many types of brain tumors and as a functional intervention. However, gamma knife treatment has a devastating effect on the normal brain parenchyma surrounding the target point. It causes increased vascular permeability, vasodilation, and swelling in endothelial cells. Ozone has antioxidant, antiapoptotic, and anti-inflammatory effects in the body. Thus, we evaluated the radioprotective effects of ozone in rats undergoing gamma knife radiation. METHODS: In the present study, 24 Sprague-Dawley male rats weighing 250-300 g in 3 groups of 8 rats each were used. The rats were selected randomly. The control group did not receive any gamma knife radiation. The other 2 groups received 50 Gy of radiation, with 1 group given ozone treatment and the other group not given ozone treatment after gamma knife radiosurgery. At 12 weeks after gamma knife radiation, the rats were sacrificed with high-dose anesthetic agents and the tissues prepared for evaluation. The slides were evaluated for necrosis, vacuolization, glial proliferation, and vascular proliferation using hematoxylin-eosin staining. Vascular endothelial growth factor (VEGF) and extracellular matrix metalloproteinase inducer (also known as CD147) were evaluated using immunohistochemical staining. RESULTS: VEGF expression in glial tissue was significantly less in the group receiving ozone (χ2 = 15.00; df = 4; P = 0.005) compared with the group that had not received ozone and was similar to the expression in the control group. CONCLUSIONS: The lower expression of VEGF in the group receiving ozone might cause less edema in the surrounding tissue owing to less degradation of vascular permeability in the rat brain tissue.
Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Permeabilidade Capilar/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Ozônio/farmacologia , Radiocirurgia/efeitos adversos , Vasodilatação/efeitos dos fármacos , Animais , Basigina/efeitos dos fármacos , Basigina/metabolismo , Basigina/efeitos da radiação , Barreira Hematoencefálica/efeitos da radiação , Encéfalo/patologia , Encéfalo/efeitos da radiação , Edema Encefálico , Permeabilidade Capilar/efeitos da radiação , Edema , Células Endoteliais/patologia , Células Endoteliais/efeitos da radiação , Ratos , Fator A de Crescimento do Endotélio Vascular/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/efeitos da radiação , Vasodilatação/efeitos da radiaçãoRESUMO
To develop a dynamic in vivo near-infrared (NIR) fluorescence imaging assay to quantify sequential changes in lung vascular permeability-surface area product (PS) in rodents. Dynamic NIR imaging methods for determining lung vascular permeability-surface area product were developed and tested on non-irradiated and 13 Gy irradiated rats with/without treatment with lisinopril, a radiation mitigator. A physiologically-based pharmacokinetic (PBPK) model of indocyanine green (ICG) pulmonary disposition was applied to in vivo imaging data and PS was estimated. In vivo results were validated by five accepted assays: ex vivo perfused lung imaging, endothelial filtration coefficient (Kf) measurement, pulmonary vascular resistance measurement, Evan's blue dye uptake, and histopathology. A PBPK model-derived measure of lung vascular permeability-surface area product increased from 2.60 ± 0.40 [CL: 2.42-2.78] mL/min in the non-irradiated group to 6.94 ± 8.25 [CL: 3.56-10.31] mL/min in 13 Gy group after 42 days. Lisinopril treatment lowered PS in the 13 Gy group to 4.76 ± 6.17 [CL: 2.12-7.40] mL/min. A much higher up to 5× change in PS values was observed in rats exhibiting severe radiation injury. Ex vivo Kf (mL/min/cm H2O/g dry lung weight), a measure of pulmonary vascular permeability, showed similar trends in lungs of irradiated rats (0.164 ± 0.081 [CL: 0.11-0.22]) as compared to non-irradiated controls (0.022 ± 0.003 [CL: 0.019-0.025]), with reduction to 0.070 ± 0.035 [CL: 0.045-0.096] for irradiated rats treated with lisinopril. Similar trends were observed for ex vivo pulmonary vascular resistance, Evan's blue uptake, and histopathology. Our results suggest that whole body dynamic NIR fluorescence imaging can replace current assays, which are all terminal. The imaging accurately tracks changes in PS and changes in lung interstitial transport in vivo in response to radiation injury.
Assuntos
Lesão Pulmonar Aguda , Permeabilidade Capilar/efeitos da radiação , Pulmão , Imagem Óptica , Lesões Experimentais por Radiação , Lesão Pulmonar Aguda/diagnóstico por imagem , Lesão Pulmonar Aguda/metabolismo , Lesão Pulmonar Aguda/fisiopatologia , Animais , Feminino , Verde de Indocianina/farmacocinética , Verde de Indocianina/farmacologia , Pulmão/irrigação sanguínea , Pulmão/diagnóstico por imagem , Pulmão/metabolismo , Pulmão/fisiopatologia , Lesões Experimentais por Radiação/diagnóstico por imagem , Lesões Experimentais por Radiação/metabolismo , Lesões Experimentais por Radiação/fisiopatologia , RatosRESUMO
Focused ultrasound (FUS) is used to locally and transiently induce blood-brain barrier (BBB) permeability, allowing targeted drug delivery to the brain. The purpose of the current study is to evaluate the potential of Vasculotide to accelerate the recovery of the BBB following FUS disruption in the TgCRND8 mouse model of amyloidosis, characteristic of Alzheimer's disease (AD). Accelerating the restoration of the BBB post-FUS would represent an additional safety procedure, which could be beneficial for clinical applications. Methods: TgCRND8 mice and their non-transgenic littermates were treated with Vasculotide (250 ng, intraperitoneal) every 48 hours for 3 months. BBB permeability was induced using FUS, in presence of intravenously injected microbubbles, in TgCRND8 and non-transgenic mice, and confirmed at time 0 by MRI enhancement using the contrast agent gadolinium. BBB closure was assessed at 6, 12 and 20 hours by MRI. In a separate cohort of animals, BBB closure was assessed at 24-hours post-FUS using Evans blue injected intravenously and followed by histological evaluation. Results: Chronic Vasculotide administration significantly reduces the ultra-harmonic threshold required for FUS-induced BBB permeability in the TgCRND8 mice. In addition, Vasculotide treatment led to a faster restoration of the BBB following FUS in TgCRND8 mice. BBB closure after FUS is not significantly different between TgCRND8 and non-transgenic mice. BBB permeability was assessed by gadolinium up to 20-hours post-FUS, demonstrating 87% closure in Vasculotide treated TgCRND8 mice, as opposed to 52% in PBS treated TgCRND8 mice, 58% in PBS treated non-transgenic mice, and 74% in Vasculotide treated non-transgenic mice. In both TgCRND8 mice and non-transgenic littermates the BBB was impermeable to Evans blue dye at 24-hours post-FUS. Conclusion: Vasculotide reduces the pressure required for microbubble ultra-harmonic onset for FUS-induced BBB permeability and it accelerates BBB restoration in a mouse model of amyloidosis, suggesting its potential clinical utility to promote vascular health, plasticity and repair in AD.
Assuntos
Doença de Alzheimer/tratamento farmacológico , Barreira Hematoencefálica/efeitos dos fármacos , Permeabilidade Capilar/efeitos dos fármacos , Fragmentos de Peptídeos/administração & dosagem , Ondas Ultrassônicas/efeitos adversos , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Barreira Hematoencefálica/diagnóstico por imagem , Barreira Hematoencefálica/patologia , Barreira Hematoencefálica/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Meios de Contraste/administração & dosagem , Modelos Animais de Doenças , Feminino , Humanos , Injeções Intraperitoneais , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Transgênicos , MicrobolhasRESUMO
Carbon- (12C-) ion radiotherapy exhibits enhanced biological effectiveness compared to photon radiotherapy, however, the contribution of its interaction with the vasculature remains debatable. The effect of high-dose 12C-ion and photon irradiation on vascular permeability in moderately differentiated rat prostate tumors was compared using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Syngeneic R3327-HI rat prostate tumors were irradiated with a single dose of either 18 or 37 Gy 12C ions, or 37 or 75 Gy 6-MV photons (sub-curative and curative dose levels, respectively). DCE-MRI was performed one day prior to and 3, 7, 14 and 21 days postirradiation. Voxel-based tumor concentration-time curves were clustered based on their curve shape and treatment response was assessed as the longitudinal changes in the relative abundance per cluster. Radiation-induced vascular damage and increased permeability occurred at day 7 postirradiation for all treatment groups except for the 75 Gy photon-irradiated group, where the onset of vascular damage was delayed until day 14. No differences between irradiation modalities were found. Therefore, early vascular damage cannot explain the higher effectiveness of 12C ions relative to photons in terms of local tumor control for this moderately differentiated prostate tumor and the applied single high doses.
Assuntos
Adenocarcinoma/radioterapia , Permeabilidade Capilar/efeitos da radiação , Carbono/uso terapêutico , Radioterapia com Íons Pesados , Imageamento por Ressonância Magnética/métodos , Fótons/uso terapêutico , Neoplasias da Próstata/radioterapia , Adenocarcinoma/sangue , Adenocarcinoma/diagnóstico por imagem , Animais , Linhagem Celular Tumoral , Relação Dose-Resposta à Radiação , Masculino , Transplante de Neoplasias , Análise de Componente Principal , Neoplasias da Próstata/irrigação sanguínea , Neoplasias da Próstata/diagnóstico por imagem , Distribuição Aleatória , Ratos , Transplante HeterotópicoRESUMO
Neuroblastoma (NB) is the most common extracranial solid tumor in infants and children, and imposes significant morbidity and mortality in this population. The aggressive chemoradiotherapy required to treat high-risk NB results in survival of less than 50%, yet is associated with significant long-term adverse effects in survivors. Boosting efficacy and reducing morbidity are therefore key goals of treatment for affected children. We hypothesize that these may be achieved by developing strategies that both focus and limit toxic therapies to the region of the tumor. One such strategy is the use of targeted image-guided drug delivery (IGDD), which is growing in popularity in personalized therapy to simultaneously improve on-target drug deposition and assess drug pharmacodynamics in individual patients. IGDD strategies can utilize a variety of imaging modalities and methods of actively targeting pharmaceutical drugs, however in vivo imaging in combination with focused ultrasound is one of the most promising approaches already being deployed for clinical applications. Over the last two decades, IGDD using focused ultrasound with "microbubble" ultrasound contrast agents (UCAs) has been increasingly explored as a method of targeting a wide variety of diseases, including cancer. This technique, known as sonopermeation, mechanically augments vascular permeability, enabling increased penetration of drugs into target tissue. However, to date, methods of monitoring the vascular bioeffects of sonopermeation in vivo are lacking. UCAs are excellent vascular probes in contrast-enhanced ultrasound (CEUS) imaging, and are thus uniquely suited for monitoring the effects of sonopermeation in tumors. Methods: To monitor the therapeutic efficacy of sonopermeation in vivo, we developed a novel system using 2D and 3D quantitative contrast-enhanced ultrasound imaging (qCEUS). 3D tumor volume and contrast enhancement was used to evaluate changes in blood volume during sonopermeation. 2D qCEUS-derived time-intensity curves (TICs) were used to assess reperfusion rates following sonopermeation therapy. Intratumoral doxorubicin (and liposome) uptake in NB was evalauted ex vivo along with associated vascular changes. Results: In this study, we demonstrate that combining focused ultrasound therapy with UCAs can significantly enhance chemotherapeutic payload to NB in an orthotopic xenograft model, by improving delivery and tumoral uptake of long-circulating liposomal doxorubicin (L-DOX) nanoparticles. qCEUS imaging suggests that changes in flow rates are highly sensitive to sonopermeation and could be used to monitor the efficacy of treatment in vivo. Additionally, initial tumor perfusion may be a good predictor of drug uptake during sonopermeation. Following sonopermeation treatment, vascular biomarkers show increased permeability due to reduced pericyte coverage and rapid onset of doxorubicin-induced apoptosis of NB cells but without damage to blood vessels. Conclusion: Our results suggest that significant L-DOX uptake can occur by increasing tumor vascular permeability with microbubble sonopermeation without otherwise damaging the vasculature, as confirmed by in vivo qCEUS imaging and ex vivo analysis. The use of qCEUS imaging to monitor sonopermeation efficiency and predict drug uptake could potentially provide real-time feedback to clinicians for determining treatment efficacy in tumors, leading to better and more efficient personalized therapies. Finally, we demonstrate how the IGDD strategy outlined in this study could be implemented in human patients using a single case study.
Assuntos
Doxorrubicina/análogos & derivados , Microbolhas , Neuroblastoma/tratamento farmacológico , Imagem de Perfusão/métodos , Ultrassonografia de Intervenção/métodos , Animais , Apoptose/efeitos dos fármacos , Determinação do Volume Sanguíneo/instrumentação , Determinação do Volume Sanguíneo/métodos , Permeabilidade Capilar/efeitos da radiação , Linhagem Celular Tumoral , Meios de Contraste/administração & dosagem , Doxorrubicina/administração & dosagem , Doxorrubicina/farmacocinética , Sistemas de Liberação de Medicamentos/métodos , Estudos de Viabilidade , Humanos , Camundongos , Neuroblastoma/irrigação sanguínea , Neuroblastoma/diagnóstico por imagem , Técnicas Fotoacústicas/instrumentação , Técnicas Fotoacústicas/métodos , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/farmacocinética , Estudos de Caso Único como Assunto , Ondas Ultrassônicas , Ultrassonografia de Intervenção/instrumentação , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The demands for region-specific, noninvasive therapies for neurologic/psychiatric conditions are growing. The rise of transcranial focused ultrasound technology has witnessed temporary and reversible disruptions of the blood-brain barrier in the brain with exceptional control over the spatial precisions and depth, all in a noninvasive manner. Starting with small animal studies about a decade ago, the technique is now being explored in nonhuman primates and humans for the assessment of its efficacy and safety. The ability to transfer exogenous/endogenous therapeutic agents, cells, and biomolecules across the blood-brain barrier opens up new therapeutic avenues for various neurologic conditions, with a possibility to modulate the excitability of regional brain function. This review addresses the technical fundamentals, sonication parameters, experimental protocols, and monitoring techniques to examine the efficacy/safety in focused ultrasound-mediated blood-brain barrier disruption and discuss its potential translations to clinical use.
Assuntos
Barreira Hematoencefálica/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Sistemas de Liberação de Medicamentos/métodos , Transtornos Mentais/terapia , Microbolhas , Ondas Ultrassônicas , Animais , HumanosRESUMO
We collected initial quantitative information on the effects of high-dose carbon (12C) ions compared to photons on vascular damage in anaplastic rat prostate tumors, with the goal of elucidating differences in response to high-LET radiation, using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Syngeneic R3327-AT1 rat prostate tumors received a single dose of either 16 or 37 Gy 12C ions or 37 or 85 Gy 6 MV photons (iso-absorbed and iso-effective doses, respectively). The animals underwent DCE-MRI prior to, and on days 3, 7, 14 and 21 postirradiation. The extended Tofts model was used for pharmacokinetic analysis. At day 21, tumors were dissected and histologically examined. The results of this work showed the following: 1. 12C ions led to stronger vascular changes compared to photons, independent of dose; 2. Tumor growth was comparable for all radiation doses and modalities until day 21; 3. Nonirradiated, rapidly growing control tumors showed a decrease in all pharmacokinetic parameters (area under the curve, Ktrans, ve, vp) over time; 4. 12C-ion-irradiated tumors showed an earlier increase in area under the curve and Ktrans than photon-irradiated tumors; 5. 12C-ion irradiation resulted in more homogeneous parameter maps and histology compared to photons; and 6. 12C-ion irradiation led to an increased microvascular density and decreased proliferation activity in a largely dose-independent manner compared to photons. Postirradiation changes related to 12C ions and photons were detected using DCE-MRI, and correlated with histological parameters in an anaplastic experimental prostate tumor. In summary, this pilot study demonstrated that exposure to 12C ions increased the perfusion and/or permeability faster and led to larger changes in DCE-MRI parameters resulting in increased vessel density and presumably less hypoxia at the end of the observation period when compared to photons. Within this study no differences were found between curative and sub-curative doses in either modality.
Assuntos
Circulação Sanguínea/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Radioterapia com Íons Pesados , Imageamento por Ressonância Magnética , Fótons/uso terapêutico , Neoplasias da Próstata/radioterapia , Animais , Proliferação de Células/efeitos da radiação , Meios de Contraste , Relação Dose-Resposta à Radiação , Masculino , Microvasos/metabolismo , Microvasos/fisiopatologia , Microvasos/efeitos da radiação , Projetos Piloto , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/fisiopatologia , Ratos , Hipóxia Tumoral/efeitos da radiaçãoRESUMO
Exposure of the gastrointestinal (GI) tract to ionizing radiation can cause acute and delayed injury. However, critical cellular targets that regulate the development of radiation-induced GI injury remain incompletely understood. Here, we investigated the role of vascular endothelial cells in controlling acute and delayed GI injury after total-abdominal irradiation (TAI). To address this, we used genetically engineered mice in which endothelial cells are sensitized to radiation due to the deletion of the tumor suppressor p53. Remarkably, we found that VE-cadherin-Cre; p53FL/FL mice, in which both alleles of p53 are deleted in endothelial cells, were not sensitized to the acute GI radiation syndrome, but these mice were highly susceptible to delayed radiation enteropathy. Histological examination indicated that VE-cadherin-Cre; p53FL/FL mice that developed delayed radiation enteropathy had severe vascular injury in the small intestine, which was manifested by hemorrhage, loss of microvessels and tissue hypoxia. In addition, using dual-energy CT imaging, we showed that VE-cadherin-Cre; p53FL/FL mice had a significant increase in vascular permeability of the small intestine in vivo 28 days after TAI. Together, these findings demonstrate that while sensitization of endothelial cells to radiation does not exacerbate the acute GI radiation syndrome, it is sufficient to promote the development of late radiation enteropathy.
Assuntos
Células Endoteliais/patologia , Células Endoteliais/efeitos da radiação , Intestinos/patologia , Intestinos/efeitos da radiação , Tolerância a Radiação , Animais , Permeabilidade Capilar/efeitos da radiação , Hipóxia Celular/efeitos da radiação , Células Endoteliais/metabolismo , Deleção de Genes , Camundongos , Fatores de Tempo , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genéticaRESUMO
Focused ultrasound (FUS)-induced disruption of the blood-brain barrier (BBB) is a non-invasive method to target drug delivery to specific brain areas that is now entering into the clinic. Recent studies have shown that the method has several secondary effects on local physiology and brain function beyond making the vasculature permeable to normally non-BBB penetrant molecules. This study uses functional MRI methods to investigate how FUS BBB opening alters the neurovascular response in the rat brain. Nine rats underwent actual and sham FUS induced BBB opening targeted to the right somatosensory cortex (SI) followed by four runs of bilateral electrical hind paw stimulus-evoked fMRI. The neurovascular response was quantified using measurements of the blood oxygen level dependent (BOLD) signal and cerebral blood flow (CBF). An additional three rats underwent the same FUS-BBB opening followed by stimulus-evoked fMRI with high resolution BOLD imaging and BOLD imaging of a carbogen-breathing gas challenge. BOLD and CBF measurements at two different stimulus durations demonstrate that the neurovascular response to the stimulus is attenuated in both amplitude and duration in the region targeted for FUS-BBB opening. The carbogen results show that the attenuation in response amplitude, but not duration, is still present when the signaling mechanism originates from changes in blood oxygenation instead of stimulus-induced neuronal activity. There is some evidence of non-local effects, including a possible global decrease in baseline CBF. All effects are resolved by 24â¯h after FUS-BBB opening. Taken together, these results suggest that FUS-BBB opening alters that state of local brain neurovascular physiology in such a way that hinders its ability to respond to demands for increased blood flow to the region. The mechanisms for this effect need to be elucidated.
Assuntos
Barreira Hematoencefálica/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Circulação Cerebrovascular/efeitos da radiação , Acoplamento Neurovascular/efeitos da radiação , Ondas Ultrassônicas/efeitos adversos , Animais , Imageamento por Ressonância Magnética , Ratos , Ratos Sprague-DawleyRESUMO
Neuromyelitis optica spectrum disorders (herein called NMO) is an autoimmune disease of the CNS characterized by astrocyte injury, inflammation, and demyelination. In seropositive NMO, immunoglobulin G autoantibodies against aquaporin-4 (AQP4-IgG) cause primary astrocyte injury. A passive transfer model of NMO was developed in which spatially targeted access of AQP4-IgG into the CNS of seropositive rats was accomplished by pulsed focused ultrasound through intact skin. Following intravenous administration of microbubbles, pulsed ultrasound at 0.5 MPa peak acoustic pressure was applied using a 1 MHz transducer with 6-cm focal length. In brain, the transient opening of the blood-brain barrier (BBB) in an approximately prolate ellipsoidal volume of diameter â¼3.5 mm and length â¼44 mm allowed entry of IgG-size molecules for up to 3-6 hours. The ultrasound treatment did not cause erythrocyte extravasation or inflammation. Ultrasound treatment in AQP4-IgG seropositive rats produced localized NMO pathology in brain, with characteristic astrocyte injury, inflammation, and demyelination after 5 days. Pathology was not seen when complement was inhibited, when non-NMO human IgG was administered instead of AQP4-IgG, or in AQP4-IgG seropositive AQP4 knockout rats. NMO pathology was similarly created in cervical spinal cord in seropositive rats. These results establish a noninvasive, spatially targeted model of NMO in rats, and demonstrate that BBB permeabilization, without underlying injury or inflammation, is sufficient to create NMO pathology in AQP4-IgG seropositive rats.
Assuntos
Aquaporina 4 , Autoanticorpos , Modelos Animais de Doenças , Neuromielite Óptica , Ondas Ultrassônicas , Animais , Barreira Hematoencefálica/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Imunoglobulina G , Ratos , Ratos Sprague-DawleyRESUMO
Focused ultrasound (FUS) is a technology capable of delivering therapeutic levels of energy through the intact skull to a tightly localized brain region. Combining the FUS pressure wave with intravenously injected microbubbles creates forces on blood vessel walls that open the blood-brain barrier (BBB). This noninvasive and localized opening of the BBB allows for targeted delivery of pharmacological agents into the brain for use in therapeutic development. It is possible to use FUS power levels such that the BBB is opened without damaging local tissues. However, open questions remain related to the effects that FUS-induced BBB opening has on brain function including local physiology and vascular hemodynamics. We evaluated the effects that FUS-induced BBB opening has on resting state functional magnetic resonance imaging (rs-fMRI) metrics. Data from rs-fMRI was acquired in rats that underwent sham FUS BBB vs. FUS BBB opening targeted to the right primary somatosensory cortex hindlimb region (S1HL). FUS BBB opening reduced the functional connectivity between the right S1HL and other sensorimotor regions, including statistically significant reduction of connectivity to the homologous region in the left hemisphere (left S1HL). The effect was observed in all three metrics analyzed: functional connectivity between anatomically defined regions, whole brain voxel-wise correlation maps based on anatomical seeds, and spatial patterns from independent component analysis. Connectivity metrics for other regions where the BBB was not perturbed were not affected. While it is not clear whether the effect is vascular or neuronal in origin, these results suggest that even safe levels of FUS BBB opening have an effect on the physiological processes that drive the signals measured by BOLD fMRI. As such these effects must be accounted for when carrying out studies using fMRI to evaluate the effects of pharmacological agents delivered via FUS-induced BBB opening.
Assuntos
Barreira Hematoencefálica/efeitos da radiação , Encéfalo/efeitos da radiação , Permeabilidade Capilar/efeitos da radiação , Rede Nervosa/efeitos da radiação , Ondas Ultrassônicas/efeitos adversos , Animais , Encéfalo/fisiologia , Mapeamento Encefálico/métodos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Vias Neurais/efeitos da radiação , Ratos , Ratos Sprague-Dawley , DescansoRESUMO
Vascular injury after radiation exposure contributes to multiple types of tissue injury through a cascade of events. Some of the earliest consequences of radiation damage include increased vascular permeability and promotion of inflammation, which is partially manifested by increased leukocyte-endothelial (L/E) interactions. We describe herein a novel intravital imaging method to evaluate L/E interactions, as a function of shear stress, and vascular permeability at multiple time points after local irradiation to the ear. This model permitted analysis of quiescent vasculature that was not perturbed by any surgical manipulation prior to imaging. To evaluate the effects of radiation on vascular integrity, fluorescent dextran was injected intravenously and its extravasation in the extravascular space surrounding the ear vasculature was measured at days 3 and 7 after 6 Gy irradiation. The vascular permeability rate increased approximately twofold at both days 3 and 7 postirradiation ( P < 0.05). Leukocyte rolling, which is indicative of L/E interactions, was significantly increased in mice at 24 h postirradiation compared to that of nonirradiated mice. To assess our model, as a means for assessing vascular radioprotectants, we treated additional cohorts of mice with a thrombopoietin mimetic, TPOm (RWJ-800088). In addition to stimulating platelet formation, thrombopoietin can protect vasculature after several forms of injury. Thus, we hypothesized that TPOm would reduce vascular permeability and L/E adhesion after localized irradiation to the ear vasculature of mice. If TPOm reduced these consequences of radiation, it would validate the utility of our intravital imaging method. TPOm reduced radiation-induced vascular leakage to control levels at day 7. Furthermore, L/E cell interactions were also reduced in irradiated mice treated with TPOm, compared with mice receiving irradiation alone, particularly at high shear stress ( P = 0.03, Kruskal-Wallis). We conclude that the ear model is useful for monitoring quiescent normal tissue vascular injury after radiation exposure. Furthermore, the application of TPOm, for preventing early inflammatory response created by damage to vascular endothelium, suggests that this drug may prove useful in reducing toxicities from radiotherapy, which damage microvasculature that critically important to tissue function.
Assuntos
Permeabilidade Capilar/efeitos dos fármacos , Permeabilidade Capilar/efeitos da radiação , Orelha/irrigação sanguínea , Leucócitos/citologia , Protetores contra Radiação/farmacologia , Veias/efeitos dos fármacos , Veias/efeitos da radiação , Animais , Adesão Celular/efeitos dos fármacos , Adesão Celular/efeitos da radiação , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/efeitos da radiação , Feminino , Leucócitos/efeitos dos fármacos , Leucócitos/efeitos da radiação , Masculino , Camundongos , Fatores de Tempo , Veias/imunologia , Veias/metabolismoRESUMO
In this study, we investigated microvascular perfusion status, changes to fat content and fatty acid composition in the bone marrow of rat femurs after total-body irradiation by quantitative permeability parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and ex vivo high-resolution magic angle spinning (HRMAS) 1H nuclear magnetic resonance spectroscopy (NMRS). Thirty-six Sprague-Dawley rats were randomly assigned to either an irradiated or nonirradiated control group. Permeability imaging using DCE-MRI and HRMAS 1H NMRS was performed before irradiation, as well as at days 4 and 7 postirradiation. The volume transfer constant (Ktrans) values increased to 2.219 ± 0.418/min ( P < 0.01) at day 4 and to 2.760 ± 0.217/min at day 7 ( P < 0.01) postirradiation. The plasma fraction (vp) values gradually decreased. The proportion of (n-6) polyunsaturated fatty acids (PUFA) gradually reached a peak at day 7, the proportion of (n-3) PUFA gradually decreased and the proportion of saturated fatty acids gradually increased. After irradiation, Ktrans at different times showed significant negative correlation with (n-3) PUFA ( r = -0.6393, P < 0.01) and significant positive correlation with (n-6) PUFA ( r = 0.6841, P < 0.05). These findings indicate that bone marrow microcirculation perfusion and vascular permeability correlated with fat content at an early time point after irradiation. A pathophysiological mechanism may exist based on fat-vascular permeability in the case of injury to bone marrow microcirculation.
Assuntos
Tecido Adiposo/efeitos da radiação , Medula Óssea/irrigação sanguínea , Permeabilidade Capilar/efeitos da radiação , Imageamento por Ressonância Magnética , Microvasos/metabolismo , Microvasos/efeitos da radiação , Irradiação Corporal Total/efeitos adversos , Tecido Adiposo/citologia , Animais , Masculino , Microvasos/diagnóstico por imagem , Ratos , Ratos Sprague-Dawley , Raios X/efeitos adversosRESUMO
Previous studies demonstrated that brief (3 to 4 min) daily application of light at 670 nm to diabetic rodents inhibited molecular and pathophysiologic processes implicated in the pathogenesis of diabetic retinopathy (DR) and reversed diabetic macular edema in small numbers of patients studied. Whether or not this therapy would inhibit the neural and vascular lesions that characterize the early stages of the retinopathy was unknown. We administered photobiomodulation (PBM) therapy daily for 8 months to streptozotocin-diabetic mice and assessed effects of PBM on visual function, retinal capillary permeability, and capillary degeneration using published methods. Vitamin D receptor and Cyp24a1 transcripts were quantified by quantitative real-time PCR, and the abundance of c-Kit+ stem cells in blood and retina were assessed. Long-term daily administration of PBM significantly inhibited the diabetes-induced leakage and degeneration of retinal capillaries and also significantly inhibited the diabetes-induced reduction in visual function. PBM also inhibited diabetes-induced reductions in retinal Cyp24a1 mRNA levels and numbers of circulating stem cells (CD45-/c-Kit+), but these effects may not account for the beneficial effects of PBM on the retinopathy. PBM significantly inhibits the functional and histopathologic features of early DR, and these effects likely are mediated via multiple mechanisms.
Assuntos
Permeabilidade Capilar/efeitos da radiação , Retinopatia Diabética/terapia , Terapia com Luz de Baixa Intensidade , Neurônios/efeitos da radiação , Retina/efeitos da radiação , Vasos Retinianos/efeitos da radiação , Visão Ocular/efeitos da radiação , Células-Tronco Adultas/metabolismo , Células-Tronco Adultas/patologia , Células-Tronco Adultas/efeitos da radiação , Animais , Biomarcadores/sangue , Biomarcadores/metabolismo , Diabetes Mellitus Experimental/complicações , Retinopatia Diabética/metabolismo , Retinopatia Diabética/patologia , Retinopatia Diabética/fisiopatologia , Progressão da Doença , Proteínas do Olho/genética , Proteínas do Olho/metabolismo , Regulação da Expressão Gênica/efeitos da radiação , Processamento de Imagem Assistida por Computador , Terapia com Luz de Baixa Intensidade/efeitos adversos , Masculino , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Proteínas do Tecido Nervoso , Neurônios/metabolismo , Neurônios/patologia , Receptores de Calcitriol/genética , Receptores de Calcitriol/metabolismo , Retina/metabolismo , Retina/patologia , Retina/fisiopatologia , Vasos Retinianos/metabolismo , Vasos Retinianos/patologia , Vasos Retinianos/fisiopatologia , Estreptozocina , Vitamina D3 24-Hidroxilase/genética , Vitamina D3 24-Hidroxilase/metabolismoRESUMO
Macroautophagy (hereafter autophagy) is a cellular "self-eating" process that is implicated in many human cancers, where it can act to either promote or suppress tumorigenesis. However, the role of autophagy in regulation of inflammation during tumorigenesis remains unclear. Here we show that autophagy is induced in the epidermis by ultraviolet (UV) irradiation and autophagy gene Atg7 promoted UV-induced inflammation and skin tumorigenesis. Atg7 regulated UV-induced cytokine expression and secretion, and promoted Ptgs2/Cox-2 expression through both a CREB1/CREB-dependent cell autonomous mechanism and an IL1B/IL1ß-dependent non-cell autonomous mechanism. Adding PGE2 increased UV-induced skin inflammation and tumorigenesis, reversing the epidermal phenotype in mice with Atg7 deletion in keratinocytes. Similar to ATG7 knockdown in human keratinocytes, ATG5 knockdown inhibited UVB-induced expression of PTGS2 and cytokines. Furthermore, ATG7 loss increased the activation of the AMPK pathway and the phosphorylation of CRTC1, and led to endoplasmic reticulum (ER) accumulation and reduction of ER stress. Inducing ER stress and inhibiting calcium influx into the ER by thapsigargin reverses the inflammation and tumorigenesis phenotype in mice with epidermal Atg7 deletion. Taken together, these findings demonstrate that deleting autophagy gene Atg7 leads to a suppression of carcinogen-induced protumorigenic inflammatory microenvironment and tumorigenesis of the epithelium.
Assuntos
Proteína 7 Relacionada à Autofagia/genética , Autofagia/efeitos da radiação , Carcinogênese/efeitos da radiação , Inflamação/patologia , Pele/patologia , Pele/efeitos da radiação , Raios Ultravioleta , Animais , Proteína 7 Relacionada à Autofagia/metabolismo , Sequência de Bases , Permeabilidade Capilar/efeitos da radiação , Carcinogênese/patologia , Núcleo Celular/metabolismo , Microambiente Celular , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Citocinas/metabolismo , Dinoprostona/metabolismo , Epiderme/metabolismo , Epiderme/efeitos da radiação , Humanos , Interleucina-1beta/metabolismo , Linfangiogênese/efeitos da radiação , Camundongos Knockout , Neovascularização Fisiológica/efeitos da radiação , Regiões Promotoras Genéticas/genética , Ligação Proteica , Transcrição Gênica/efeitos da radiaçãoRESUMO
PURPOSE: Blood-tumor barrier is a limiting factor for effectiveness of systemic therapy to brain metastases. This study aimed to assess the extent and time course of BTB opening in BM following whole-brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS) to determine optimal timing for systemic therapy. MATERIALS AND METHOD: 30 patients received WBRT or SRS and a total of 64 metastatic lesions were analyzed. Dynamic contrast-enhanced MRI were acquired, to quantify a transfer constant (Ktrans), pre-RT, 1-2weeks after starting RT (Wk1-2), and 1-month post-RT (1M post-RT). Lesions were categorized as either low or high permeability based upon the pre-RT percentage volume of a lesion with Ktrans>0.005min-1 (%Vall) less or greater than 50%. Time-course changes of %Vall after RT were analyzed. RESULTS: Fifty-seven lesions had high-permeability and seven had low-permeability at baseline. Intra-patient and inter-lesion heterogeneity was observed in six patients who had both low- (n=7) and high-permeability lesions (n=10). Also, lesion permeability showed a significant size-effect at baseline. For high-permeability lesions, either received WBRT (n=43) or SRS (n=14), %Vall decreased non-significantly following RT (from 85.4% pre-RT to 76.9% 1M post-RT). For low-permeability lesions (n=7, all received WBRT), %Vall increased from 5.6% pre-RT to 30.2% at Wk1-2 and to 52.6% 1M-post (p=0.01). CONCLUSION: Our preliminary results suggest that 2-4weeks after RT, when BTB opening is high for both low- and high-permeability brain metastatic lesions, could be optimal time to start systemic therapy.
Assuntos
Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/efeitos da radiação , Neoplasias Encefálicas/irrigação sanguínea , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/secundário , Permeabilidade Capilar/efeitos da radiação , Irradiação Craniana/métodos , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Radiocirurgia/métodos , Estudos RetrospectivosRESUMO
PURPOSE: To compare the blood-brain barrier permeability changes induced by synchrotron microbeam radiation therapy (MRT, which relies on spatial fractionation of the incident x-ray beam into parallel micron-wide beams) with changes induced by a spatially uniform synchrotron x-ray radiation therapy. METHODS AND MATERIALS: Male rats bearing malignant intracranial F98 gliomas were randomized into 3 groups: untreated, exposed to MRT (peak and valley dose: 241 and 10.5 Gy, respectively), or exposed to broad beam irradiation (BB) delivered at comparable doses (ie, equivalent to MRT valley dose); both applied by 2 arrays, intersecting orthogonally the tumor region. Vessel permeability was monitored in vivo by magnetic resonance imaging 1 day before (T-1) and 1, 2, 7, and 14 days after treatment start. To determine whether physiologic parameters influence vascular permeability, we evaluated vessel integrity in the tumor area with different values for cerebral blood flow, blood volume, edema, and tissue oxygenation. RESULTS: Microbeam radiation therapy does not modify the vascular permeability of normal brain tissue. Microbeam radiation therapy-induced increase of tumor vascular permeability was detectable from T2 with a maximum at T7 after exposure, whereas BB enhanced vessel permeability only at T7. At this stage MRT was more efficient at increasing tumor vessel permeability (BB vs untreated: +19.1%; P=.0467; MRT vs untreated: +44.8%; P<.0001), and its effects lasted until T14 (MRT vs BB, +22.6%; P=.0199). We also showed that MRT was more efficient at targeting highly oxygenated (high blood volume and flow) and more proliferative parts of the tumor than BB. CONCLUSIONS: Microbeam radiation therapy-induced increased tumor vascular permeability is: (1) significantly greater; (2) earlier and more prolonged than that induced by BB irradiation, especially in highly proliferative tumor areas; and (3) targets all tumor areas discriminated by physiologic characteristics, including those not damaged by homogeneous irradiation.