Targeting brain tumors by intra-arterial delivery of cell-penetrating peptides: a novel approach for primary and metastatic brain malignancy.

Computational modeling shows that intra-arterial delivery is most efficient when the delivered drugs rapidly and avidly bind to the target site. The cell-penetrating peptide trans-activator of transcription (TAT) is a candidate carrier molecule that could mediate such specificity for brain tumor chemotherapeutics. To test this hypothesis we first performed in vitro studies testing the uptake of TAT by one primary and three potentially metastatic brain cancer cell lines (9L, 4T-1, LLC, SKOV-3). Then we performed in vivo studies in a rat model where TAT was delivered either intra-arterially (IA) or intravenously (IV) to 9L brain tumors. We observed robust uptake of TAT by all tumor cell lines in vitro. Flow cytometry and confocal microscopy revealed a rapid uptake of fluorescein-labeled TAT within 5 min of exposure to the cancer cells. IA injections done under transient cerebral hypoperfusion (TCH) generated a four-fold greater tumor TAT concentration compared to conventional IV injections. We conclude that it is feasible to selectively target brain tumors with TAT-linked chemotherapy by the IA-TCH method.

Flow arrest intra-arterial delivery of small TAT-decorated and neutral micelles to gliomas.

The cell-penetrating trans-activator of transcription (TAT) is a cationic peptide derived from human immunodeficiency virus-1. It has been used to facilitate macromolecule delivery to various cell types. This cationic peptide is capable of crossing the blood-brain barrier and therefore might be useful for enhancing the delivery of drugs that target brain tumors. Here we test the efficiency with which relatively small (20 nm) micelles can be delivered by an intra-arterial route specifically to gliomas. Utilizing the well-established method of flow-arrest intra-arterial injection we compared the degree of brain tumor deposition of cationic TAT-decorated micelles versus neutral micelles. Our in vivo and post-mortem analyses confirm glioma-specific deposition of both TAT-decorated and neutral micelles. Increased tumor deposition conferred by the positive charge on the TAT-decorated micelles was modest. Computational modeling suggested a decreased relevance of particle charge at the small sizes tested but not for larger particles. We conclude that continued optimization of micelles may represent a viable strategy for targeting brain tumors after intra-arterial injection. Particle size and charge are important to consider during the directed development of nanoparticles for intra-arterial delivery to brain tumors.

Safety, feasibility, and optimization of intra-arterial mitoxantrone delivery to gliomas.

Mitoxantrone is a highly cytotoxic antineoplastic drug, however, its poor penetration of the blood-brain barrier has limited its role in the treatment of brain cancers. We hypothesize that intra-arterial (IA) delivery of mitoxantrone may enhance its capacity for regional brain deposition thus expanding its potential as a brain tumor therapy agent. In this study we assessed the dose-response characteristics as well as the feasibility and safety of mitoxantrone delivery to the brain and specifically to gliomas in a rodent model. We show that delivery optimization utilizing the technique of intra-arterial transient cerebral hypoperfusion (IA-TCH) facilitates achieving the highest peak- and end- brain drug concentrations as compared to intravenous and IA delivery without hypoperfusion. Additionally, we observed significant tumor-specific uptake of mitoxantrone when delivered by the IA-TCH method. No untoward effects of IA-TCH delivery of mitoxantrone were observed. The IA-TCH method is shown to be a safely tolerated and feasible strategy for delivering mitoxantrone to tumors in the glioma model tested. Additional investigation is warranted to determine if IA-TCH delivery of mitoxantrone produces clinically relevant benefit.

Computational pharmacokinetic rationale for intra-arterial delivery to the brain.

Intra-arterial (IA) drug delivery has been proposed for the treatment of a wide range of brain diseases, including malignant brain tumors. However, pharmacokinetic optimization for IA drug delivery to the brain remains a challenge. In this report, we apply and expand the well-established Dedrick model of IA drug delivery to the brain and test the effects of modifying drug and delivery parameters. These simulations show that altering the properties of candidate drugs and physiological variables can have profound effects on regional deposition after IA injections. We show that drug and physiological optimization aimed at rapid drug extraction and sustained retention is necessary to maximize regional deposition after of IA injections.

Liposome size and charge optimization for intraarterial delivery to gliomas.

Nanoparticles such as liposomes may be used as drug delivery vehicles for brain tumor therapy. Particle geometry and electrostatic properties have been hypothesized to be important determinants of effective tumor targeting after intraarterial injection. In this study, we investigate the combined roles of liposome size and surface charge on the effectiveness of delivery to gliomas after intraarterial injection. Intracarotid injection of liposomes was performed in separate cohorts of both healthy and C6 glioma-bearing Sprague Dawley rats after induction of transient cerebral hypoperfusion. Large (200 nm) and small (60-80 nm) fluorescent dye-loaded liposomes that were either cationic or neutral in surface charge were utilized. Delivery effectiveness was quantitatively measured both with real-time, in vivo and postmortem diffuse reflectance spectroscopy. Semi-quantitative multispectral fluorescence imaging was also utilized to assess the pattern and extent of liposome targeting within tumors. Large cationic liposomes demonstrated the most effective hemispheric and glioma targeting of all the liposomes tested. Selective large cationic liposome retention at the site of glioma growth was observed. The liposome deposition pattern within tumors after intraarterial injection was variable with both core penetration and peripheral deposition observed in specific tumors. This study provides evidence that liposome size and charge are important determinants of effective brain and glioma targeting after intraarterial injection. Our results support the future development of 200-nm cationic liposomal formulations of candidate intraarterial anti-glioma agents for further pre-clinical testing.

Cationizable lipid micelles as vehicles for intraarterial glioma treatment.

The relative abundance of anionic lipids on the surface of endothelia and on glioma cells suggests a workable strategy for selective drug delivery by utilizing cationic nanoparticles. Furthermore, the extracellular pH of gliomas is relatively acidic suggesting that tumor selectivity could be further enhanced if nanoparticles can be designed to cationize in such an environment. With these motivating hypotheses the objective of this study was to determine whether nanoparticulate (20 nm) micelles could be designed to improve their deposition within gliomas in an animal model. To test this, we performed intra-arterial injection of micelles labeled with an optically quantifiable dye. We observed significantly greater deposition (end-tissue concentration) of cationizable micelles as compared to non-ionizable micelles in the ipsilateral hemisphere of normal brains. More importantly, we noted enhanced deposition of cationizable as compared to non-ionizable micelles in glioma tissue as judged by semiquantitative fluorescence analysis. Micelles were generally able to penetrate to the core of the gliomas tested. Thus we conclude that cationizable micelles may be constructed as vehicles for facilitating glioma-selective delivery of compounds after intraarterial injection.

Suppression of Shear Banding and Transition to Necking and Homogeneous Flow in Nanoglass Nanopillars.

In order to improve the properties of metallic glasses (MG) a new type of MG structure, composed of nanoscale grains, referred to as nanoglass (NG), has been recently proposed. Here, we use large-scale molecular dynamics (MD) simulations of tensile loading to investigate the deformation and failure mechanisms of Cu64Zr36 NG nanopillars with large, experimentally accessible, 50 nm diameter. Our results reveal NG ductility and failure by necking below the average glassy grain size of 20 nm, in contrast to brittle failure by shear band propagation in MG nanopillars. Moreover, the results predict substantially larger ductility in NG nanopillars compared with previous predictions of MD simulations of bulk NG models with columnar grains. The results, in excellent agreement with experimental data, highlight the substantial enhancement of plasticity induced in experimentally relevant MG samples by the use of nanoglass architectures and point out to exciting novel applications of these materials.

Intraarterial drug delivery for glioblastoma mutiforme: Will the phoenix rise again?

Intraarterial (IA) drug delivery is a physiologically appealing strategy as drugs are widely distributed throughout the tumor capillary network and high regional tissue concentrations can be achieved with low total doses. IA treatment of glioblastoma multiforme (GBM) has been attempted since the 1950s but success has been elusive. Although IA treatments have been embraced for the treatment of retinoblastoma and advanced liver cancers, this has not been the case for GBM. The development of IA drug delivery for the treatment of brain cancer over the last several decades reveals a number of critical oversights. For example, very few studies took into consideration the underlying hydrodynamic factors. Therapeutic failures were often blamed on an inability to penetrate the blood brain barrier or on the streaming of drugs. Similarly, there were few methods to investigate the ultra-fast pharmacokinetics of IA drugs. Despite past failures, clinical interest in IA drugs for the treatment of GBM persists. The advent of modern imaging methods along with a better understanding of hydrodynamics factors, better appreciation of the complex morphology of GBM, improved drug selection and formulations, and development of methods to minimize treatment-related neurological injury, promise to considerably advance the application of IA drugs for GBM treatment. There are several clinical trials with IA treatments in the National Trial Registry that are actively recruiting patients. This review of IA drug delivery for GBM treatment is therefore timely and is intended to assess how this method of drug delivery could be better applied to future treatments.

Reassessing the Role of Intra-Arterial Drug Delivery for Glioblastoma Multiforme Treatment.

Effective treatment for glioblastoma (GBM) will likely require targeted delivery of several specific pharmacological agents simultaneously. Intra-arterial (IA) delivery is one technique for targeting the tumor site with multiple agents. Although IA chemotherapy for glioblastoma (GBM) has been attempted since the 1950s, the predicted benefits remain unproven in clinical practice. This review focuses on innovative approaches to IA drug delivery in treating GBM. Guided by novel in vitro and in vivo optical measurements, newer pharmacokinetic models promise to better define the complex relationship between background cerebral blood flow and drug injection parameters. Advanced optical technologies and tracers, unique nanoparticles designs, new cellular targets, and rational drug formulations are continuously modifying the therapeutic landscape for GBM. Personalized treatment approaches are emerging; however, such tailored approaches will largely depend on effective drug delivery techniques and on the ability to simultaneously deliver multidrug regimens. These new paradigms for tumor-selective drug delivery herald dramatic improvements in the effectiveness of IA chemotherapy for GBM. Therefore, within this context of so-called "precision medicine," the role of IA delivery for GBM is thoroughly reassessed.

Cerebral hypoperfusion-assisted intra-arterial deposition of liposomes in normal and glioma-bearing rats.

BACKGROUND: Optimizing liposomal vehicles for targeted delivery to the brain has important implications for the treatment of brain tumors. The promise of efficient, brain-specific delivery of chemotherapeutic compounds via liposomal vehicles has yet to be achieved in clinical practice. Intra-arterial injection of specially designed liposomes may facilitate efficient delivery to the brain and to gliomas. OBJECTIVE: To test the hypothesis that cationic liposomes may be effectively delivered to both normal and glioma-bearing brain tissue utilizing a strategy of intra-arterial injection during transient cerebral hypoperfusion. METHODS: Cationic, anionic, and neutral liposomes were separately injected via the internal carotid artery of healthy rats during transient cerebral hypoperfusion. Rats bearing C6 gliomas were similarly injected with cationic liposomes. Liposomes were loaded with DilC18(5) dye whose concentrations can be measured by light absorbance and fluorescence methods. RESULTS: After intra-arterial injection, a robust uptake of cationic in comparison with anionic and neutral liposomes into brain parenchyma was observed by diffuse reflectance spectroscopy. Postmortem multispectral fluorescence imaging revealed that liposomal cationic charge was associated with more efficient delivery to the brain. Cationic liposomes were also readily observed within glioma tissue after intra-arterial injection. However, over time, cationic liposomes were retained longer and at higher concentrations in the surrounding, peritumoral brain than in the tumor core. CONCLUSION: This study demonstrates the feasibility of cationic liposome delivery to brain and glioma tissue after intra-arterial injection. Highly cationic liposomes directly delivered to the brain via an intracarotid route may represent an effective method for delivering antiglioma agents.

Revisiting intra-arterial drug delivery for treating brain diseases or is it "déjà-vu, all over again"?

For over six decades intra-arterial (IA) drugs have been sporadically used for the treatment of lethal brain diseases. In recent years considerable advance has been made in the IA treatment of retinoblastomas, liver and locally invasive breast cancers, but relatively little progress has been made in the treatment of brain cancers. High resting blood flow and the presence of the blood-brain barrier (BBB), makes IA delivery to the brain tissue far more challenging, compared to other organs. The lack of advance in the field is also partly due to the inability to understand the complex pharmacokinetics of IA drugs as it is difficult to track drug concentrations in sub-second time frame by conventional chemical methods. The advances in optical imaging now provide unprecedented insights into the pharmacokinetics of IA drug and optical tracer delivery. Novel delivery methods, improved IA drug formulations, and optical pharmacokinetics, present us with untested paradigms in pharmacology that could lead to new therapeutic interventions for brain cancers and stroke. The object of this review is to bring into focus the current practice, problems, and the potential of IA drug delivery for treating brain diseases. A concerted effort is needed at basic sciences (pharmacology and drug imaging), and translational (drug delivery techniques and protocol development) levels by the interventional neuroradiology community to advance the field.

Predictive maps for stochastic nonaffine stiffening and damage in fibrous networks.

The macroscopic responses of synthetic and natural filamentous networks are determined by a combination of microstructure and filament properties. Biofilament networks such as those of actin and fibrin have become vehicles for studying important concepts in mechanics such as rigidity percolation, linearity and nonlinearity, isotropy and anisotropy, affinity and nonaffinity, hardening and softening, bending and stretching transitions, etc. In this work, we consider generic fibrous network architectures to map out their mechanical responses over a wide range of filament properties. Using the finite element method, we perform two-dimensional simulations of discrete networks subjected to shear deformation. These simulations encompass stochastic effects arising from network topology (filament arrangement, orientation, and length distribution) and the thermally activated crosslink scission. We study the mechanics of these random networks up to a strain of 10%, including damage that is induced by crosslink scission. The response is nonlinear and the initial elastic modulus alone is not sufficient to give an understanding about the overall response. We show that the nonlinear elastic response of the network can be captured using a few parameters that depend on some well known length scales in network mechanics. For networks with filament density above the rigidity percolation threshold, by increasing filament density and bending stiffness, we observe a crossover from the bending dominated elastically compliant stiffening regime to a stretching dominated rigid nonstiffening regime. We show that in the bending dominated regime there are large deviations from the predictions of affine continuum theories. We also give a simple qualitative model for describing the contours of the incubation strain which marks the onset of damage in networks.

Spatial mapping of drug delivery to brain tissue using hyperspectral spatial frequency-domain imaging.

We present an application of spatial frequency-domain imaging (SFDI) to the wide-field imaging of drug delivery to brain tissue. Measurements were compared with values obtained by a previously validated variation of diffuse reflectance spectroscopy, the method of optical pharmacokinetics (OP). We demonstrate a crosscorrelation between the two methods for absorption extraction and drug concentration determination in both experimental tissue phantoms and freshly extracted rodent brain tissue. These methods were first used to assess intra-arterial (IA) delivery of cationic liposomes to brain tissue in Sprague Dawley rats under transient cerebral hypoperfusion. Results were found to be in agreement with previously published experimental data and pharmacokinetic models of IA drug delivery. We then applied the same scheme to evaluate IA mitoxantrone delivery to glioma-bearing rats. Good correlation was seen between OP and SFDI determined concentrations taken from normal and tumor averaged sites. This study shows the feasibility of mapping drug/tracer distributions and encourages the use of SFDI for spatial imaging of tissues for drug/tracer-tagged carrier deposition and pharmacokinetic studies.

Cationic surface charge enhances early regional deposition of liposomes after intracarotid injection.

Rapid first pass uptake of drugs is necessary to increase tissue deposition after intraarterial (IA) injection. Here we tested whether brain tissue deposition of a nanoparticulate liposomal carrier could be enhanced by coordinated manipulation of liposome surface charge and physiological parameters, such as IA injection during transient cerebral hypoperfusion (TCH). Different degrees of blood-brain barrier disruption were induced by focused ultrasound in three sets of Sprague-Dawley rats. Brain tissue retention was then compared for anionic, cationic, and charge-neutral liposomes after IA injection combined with TCH. The liposomes contained a non-exchangeable carbocyanine membrane optical label that could be quantified using diffuse reflectance spectroscopy (DRS) or visualized by multispectral imaging. Real-time concentration-time curves in brain were obtained after each liposomal injection. Having observed greater tissue retention of cationic liposomes compared to other liposomes in all three groups, we tested uptake of cationic liposomes in C6 tumor bearing rats. DRS and multispectral imaging of postmortem sections revealed increased liposomal uptake by the C6 brain tumor as compared to non-tumor contralateral hemisphere. We conclude that regional deposition of liposomes can be enhanced without BBB disruption using IA injection of cationic liposomal formulations in healthy and C6 tumor bearing rats.

Transient cerebral hypoperfusion assisted intraarterial cationic liposome delivery to brain tissue.

Transient cerebral hypoperfusion (TCH) has empirically been used to assist intraarterial (IA) drug delivery to brain tumors. Transient (<3 min) reduction of cerebral blood flow (CBF) occurs during many neuro- and cardiovascular interventions and has recently been used to better target IA drugs to brain tumors. In the present experiments, we assessed whether the effectiveness of IA delivery of cationic liposomes could be improved by TCH. Cationic liposomes composed of 1:1 DOTAP:PC (dioleoyl-trimethylammonium-propane:phosphatidylcholine) were administered to three groups of Sprague-Dawley rats. In the first group, we tested the effect of blood flow reduction on IA delivery of cationic liposomes. In the second group, we compared TCH-assisted IA liposomal delivery versus intravenous (IV) administration of the same dose. In the third group, we assessed retention of cationic liposomes in brain 4 h after TCH assisted delivery. The liposomes contained a near infrared dye, DilC18(7), whose concentration could be measured in vivo by diffuse reflectance spectroscopy. IA injections of cationic liposomes during TCH increased their delivery approximately fourfold compared to injections during normal blood flow. Optical pharmacokinetic measurements revealed that relative to IV injections, IA injection of cationic liposomes during TCH produced tissue concentrations that were 100-fold greater. The cationic liposomes were retained in the brain tissue 4 h after a single IA injection. There was no gross impairment of neurological functions in surviving animals. Transient reduction in CBF significantly increased IA delivery of cationic liposomes in the brain. High concentrations of liposomes could be delivered to brain tissue after IA injections with concurrent TCH while none could be detected after IV injection. IA-TCH injections were well tolerated and cationic liposomes were retained for at least 4 h after IA administration. These results should encourage development of cationic liposomal formulations of chemotherapeutic drugs and their IA delivery during TCH.

Paradoxical increase in the bispectral index during deep anesthesia in New Zealand white rabbits.

Objective monitoring of the level of anesthesia is crucial in carefully controlled translational neuroscience studies. The usefulness of bispectral index (BIS) in monitoring human anesthesia is well established. However, the validity of its application remains unproven in laboratory animals. We assessed whether BIS could be used reliably in monitoring the depth of deep anesthesia in 8 New Zealand white rabbits. Experimental baseline anesthesia was maintained with continuous infusion of propofol and administration of isoflurane, both of which were titrated to EEG activity. The rabbits were allocated randomly to receive 3 increasing concentrations of common anesthetic drugs (etomidate, propofol, and isoflurane) aimed to produce burst suppression of EEG activity yielding at least 10 s of sustained EEG silence. Rabbits had a 20-min recovery interval between challenges. Transient cerebral hypoperfusion to produce reversible EEG silence due to ischemia was induced as a fourth challenge, followed by terminal arrest, in each animal. BIS, EEG, and physiologic data were analyzed for each rabbit. We observed stable BIS values in the range of 40 to 60 during the administration of baseline anesthesia. However, as the depth of anesthesia deepened with the anesthetic drug challenges, the BIS value paradoxically increased with increasing doses. The BIS signal quality index declined while the total power decreased. In contrast to these unexpected results, BIS values decreased rapidly to near 0 during terminal arrest, as expected. Therefore, we do not consider BIS to be a useful method for monitoring deep levels of anesthesia in laboratory rabbits.

Real-time hemodynamic response and mitochondrial function changes with intracarotid mannitol injection.

UNLABELLED: Disruption of blood brain barrier (BBB) is used to enhance chemotherapeutic drug delivery. The purpose of this study was to understand the time course of hemodynamic and metabolic response to intraarterial (IA) mannitol infusions in order to optimize the delivery of drugs for treating brain tumors. PRINCIPAL RESULTS: We compared hemodynamic response, EEG changes, and mitochondrial function as judged by relative changes in tissue NADH concentrations, after intracarotid (IC) infusion of equal volumes of normal saline and mannitol in our rabbit IC drug delivery model. We observed significantly greater, though transient, hyperemic response to IC infusion of mannitol compared to normal saline. Infusion of mannitol also resulted in a greater increase in tissue NADH concentrations relative to the baseline. These hemodynamic, and metabolic changes returned to baseline within 5min of mannitol injection. CONCLUSION: Significant, though transient, changes in blood flow and brain metabolism occur with IA mannitol infusion. The observed transient hyperemia would suggest that intravenous (IV) chemotherapy should be administered either just before, or concurrent with IA mannitol injections. On the other hand, IA chemotherapy should be delayed until the peak hyperemic response has subsided.

Noninvasive in vivo optical assessment of blood brain barrier permeability and brain tissue drug deposition in rabbits.

Osmotic disruption of the blood brain barrier (BBB) by intraarterial mannitol injection is sometimes the key step for the delivery of chemotherapeutic drugs to brain tissue. BBB disruption (BBBD) with mannitol, however, can be highly variable and could impact local drug deposition. We use optical pharmacokinetics, which is based on diffuse reflectance spectroscopy, to track in vivo brain tissue concentrations of indocyanine green (ICG), an optical reporter used to monitor BBBD, and mitoxantrone (MTX), a chemotherapy agent that does not deposit in brain tissue without BBBD, in anesthetized New Zealand white rabbits. Results show a significant increase in the tissue ICG concentrations with BBBD, and our method is able to track the animal-to-animal variation in tissue ICG and MTX concentrations after BBBD. The tissue concentrations of MTX increase with barrier disruption and are found to be correlated to the degree of disruption, as assessed by the ICG prior to the injection of the drug. These findings should encourage the development of tracers and optical methods capable of quantifying the degree of BBBD, with the goal of improving drug delivery.

Convection enhanced drug delivery of BDNF through a microcannula in a rodent model to strengthen connectivity of a peripheral motor nerve bridge model to bypass spinal cord injury.

Models employing peripheral nerve to bypass spinal cord injury (SCI), although highly promising, may benefit from improved nerve regeneration and motor bridge connectivity. Recent studies have demonstrated that neuronal growth factor-induced enhancement of endogenous neurorestoration may improve neuronal connectivity after severe neurologic injury, particularly if delivered intraparenchymally with zero-order kinetics. We sought to investigate the effect of convection-enhanced delivery of brain-derived neurotrophic factor (BDNF), a neuronal growth factor, on the connectivity of a peripheral motor-nerve bridge in a rodent model using electrophysiology and immunohistochemistry (IHC). Spinal cords of 29 female rats were hemisected at the L1 level. Ipsilateral T13 peripheral nerves were dissected from their muscular targets distally, while maintaining their connections with the spinal cord, and inserted caudal to the injury site to establish the nerve bridge. A microcannula attached to a six-week mini-osmotic pump was used to deliver either BDNF (n=12), saline (n=14), or fluorescein dye (n=3) directly into the spinal cord parenchyma between the site of nerve insertion and hemisection to a depth of 2mm into the area of the lateral motor pool. After four weeks, gastrocnemius muscle activation was assessed electromyographically in five animals from each group. Spinal cords were harvested and analyzed with IHC for cannula-associated injury, and nerve regeneration. Strength of motor bridge connection was illustrated by electrophysiology data. Intraspinal BDNF levels were measured using enzyme-linked immunosorbent assay. IHC revealed increased intraparenchymal BDNF concentration at the nerve bridge insertion site with evidence of minimal trauma from cannulation. BDNF infusion resulted in stronger connections between bridge nerves and spinal motor axons. Bridge nerve electrical stimulation in BDNF-treated rats evoked hind leg electromyogram responses of shorter latency and larger amplitudes than saline-infused controls. Thus, direct convection-assisted delivery provides reliable administration of potent growth factors directly into the spinal cord parenchyma. Delivery of BDNF at the peripheral nerve bridge site results in enhanced connectivity of the peripheral motor bridge in a rodent model of SCI.

The feasibility of real-time in vivo optical detection of blood-brain barrier disruption with indocyanine green.

Osmotic disruption of the blood-brain barrier (BBB) by intraarterial mannitol injection is sometimes required for the delivery of chemotherapeutic drugs to brain tissue. Osmotic disruption is affected by a number of factors, and there is a significant variability in the degree and distribution of BBB disruption in clinical and experimental settings. Brain tissue concentrations of indocyanine green (ICG) can be measured by optical techniques. The aim of this experiment was to determine whether the disruption of the BBB significantly altered the regional pharmacokinetics of ICG. We were able to track in vivo brain tissue concentrations of ICG in 13 New Zealand white rabbits by employing a novel optical approach. Evan's blue was used to assess the distribution of BBB disruption on post mortem examination. BBB disruption by intraarterial mannitol injection was found to be highly variable, and only five of the 13 animals demonstrated the disruption at the site of optical measurements. In these animals, we observed a ninefold increase in ICG concentrations and fourfold increase in the area under the concentration-time curve, compared to those without BBB disruption at the site of measurement. This study shows the feasibility of optical monitoring of BBB disruption with intravenous (IV) ICG injections. Virtual real-time optical monitoring of the BBB disruption could help improve intraarterial delivery of chemotherapeutic drugs.