Project description:Recent advances in maximum safe glioma resection have included the introduction of a host of visualization techniques to complement intraoperative white-light imaging of tumors. However, barriers to the effective use of these techniques within the central nervous system remain. In the healthy brain, the blood-brain barrier ensures the stability of the sensitive internal environment of the brain by protecting the active functions of the central nervous system and preventing the invasion of microorganisms and toxins. Brain tumors, however, often cause degradation and dysfunction of this barrier, resulting in a heterogeneous increase in vascular permeability throughout the tumor mass and outside it. Thus, the characteristics of both the blood-brain and blood-brain tumor barriers hinder the vascular delivery of a variety of therapeutic substances to brain tumors. Recent developments in fluorescent visualization of brain tumors offer improvements in the extent of maximal safe resection, but many of these fluorescent agents must reach the tumor via the vasculature. As a result, these fluorescence-guided resection techniques are often limited by the extent of vascular permeability in tumor regions and by the failure to stain the full volume of tumor tissue. In this review, we describe the structure and function of both the blood-brain and blood-brain tumor barriers in the context of the current state of fluorescence-guided imaging of brain tumors. We discuss features of currently used techniques for fluorescence-guided brain tumor resection, with an emphasis on their interactions with the blood-brain and blood-tumor barriers. Finally, we discuss a selection of novel preclinical techniques that have the potential to enhance the delivery of therapeutics to brain tumors in spite of the barrier properties of the brain.
Project description:Insults to the cerebral cortex, such as trauma, ischemia or infections, may result in the development of epilepsy, one of the most common neurological disorders. Previous studies have suggested that perturbations in neurovascular integrity and breakdown of the blood-brain barrier (BBB) lead to neuronal hypersynchronization and epileptiform activity, but the underlying mechanisms are unknown. As with BBB opening, treatment with albumin or with TGF-?1 results in the development of hypersynchronized epileptiform activity. Given the latent period before the appearance of epileptiform activity, we hypothesized the underlying mechanism is a transcriptional response which would be similar for BBB breakdown and exposure to albumin or TGF-?1. In search of a common pathway and transcriptional activation pattern we performed a genome wide analysis. Genomic expression analyses demonstrated similar expression patterns for BBB opening, albumin and TGF-?1 exposure. Most importantly, TGF-? pathway blockers suppressed most albumin-induced transcriptional changes. RNA was extracted from cortical regions of rats treated with sodium deoxycholate (DOC, to induce BBB opening), albumin or TGF-?1 for various durations (7/8, 24, 48hr). Control RNA was extracted from a sham-operated animal and one array was run for each treatment and time point A second set of animals (labeled as Set 2) was treated with either albumin (n=3) or albumin in the presence of TGF-? receptor blockers (n=4; TGF-?R1 kinase activity inhibitor SB431542 and TGF-?R2 antibody) and sacrificed 24 hr following treatment. Sham-operated animals served as controls (n=2).
Project description:Insults to the cerebral cortex, such as trauma, ischemia or infections, may result in the development of epilepsy, one of the most common neurological disorders. Previous studies have suggested that perturbations in neurovascular integrity and breakdown of the blood-brain barrier (BBB) lead to neuronal hypersynchronization and epileptiform activity, but the underlying mechanisms are unknown. As with BBB opening, treatment with albumin or with TGF-β1 results in the development of hypersynchronized epileptiform activity. Given the latent period before the appearance of epileptiform activity, we hypothesized the underlying mechanism is a transcriptional response which would be similar for BBB breakdown and exposure to albumin or TGF-β1. In search of a common pathway and transcriptional activation pattern we performed a genome wide analysis. Genomic expression analyses demonstrated similar expression patterns for BBB opening, albumin and TGF-β1 exposure. Most importantly, TGF-β pathway blockers suppressed most albumin-induced transcriptional changes.
Project description:Purposenab-paclitaxel demonstrates improved clinical efficacy compared with conventional Cremophor EL (CrEL)-paclitaxel in multiple tumor types. This study explored the distinctions in drug distribution between nab-paclitaxel and CrEL-paclitaxel and the underlying mechanisms.MethodsUptake and transcytosis of paclitaxel were analyzed by vascular permeability assay across human endothelial cell monolayers. The tissue penetration of paclitaxel within tumors was evaluated by local injections into tumor xenografts and quantitative image analysis. The distribution profile of paclitaxel in solid-tumor patients was assessed using pharmacokinetic modeling and simulation.ResultsLive imaging demonstrated that albumin and paclitaxel were present in punctae in endothelial cells and could be observed in very close proximity, suggesting cotransport. Uptake and transport of albumin, nab-paclitaxel and paclitaxel were inhibited by clinically relevant CrEL concentrations. Further, nab-paclitaxel causes greater mitotic arrest in wider area within xenografted tumors than CrEL- or dimethyl sulfoxide-paclitaxel following local microinjection, demonstrating enhanced paclitaxel penetration and uptake by albumin within tumors. Modeling of paclitaxel distribution in patients with solid tumors indicated that nab-paclitaxel is more dependent upon transporter-mediated pathways for drug distribution into tissues than CrEL-paclitaxel. The percent dose delivered to tissue via transporter-mediated pathways is predicted to be constant with nab-paclitaxel but decrease with increasing CrEL-paclitaxel dose.ConclusionsCompared with CrEL-paclitaxel, nab-paclitaxel demonstrated more efficient transport across endothelial cells, greater penetration and cytotoxic induction in xenograft tumors, and enhanced extravascular distribution in patients that are attributed to carrier-mediated transport. These observations are consistent with the distinct clinical efficacy and toxicity profile of nab-paclitaxel.
Project description:BackgroundThe evidence that albumin-bound paclitaxel (nab-paclitaxel) is safe and efficacious for the treatment of many types of malignant tumors is continuously increasing. However, the evidence and clinical data of nab-paclitaxel and gemcitabine in metastatic soft tissue sarcoma (STS) treatment are rare.MethodsThe clinical data of metastatic STS patients who received nab-paclitaxel/ gemcitabine chemotherapy between January 2019 and February 2020 were retrospectively analysed. All these patients were treated with nab-paclitaxel/ gemcitabine only after doxorubicin-based chemotherapy had failed. We evaluated the effectiveness and safety of nab-paclitaxel and gemcitabine in these patients.ResultsA total of 17 patients treated with nab-paclitaxel/ gemcitabine were enrolled in this study. One patient with angiosarcoma achieved complete response, 6 patients had partial response, 5 patients achieved stable disease, and 5 patients had progressive disease. The average diameter change in target lesion from baseline was - 19.06 ± 45.74%. And median progression free survival was 6 months (95% CI, 2-9 months). Grade 3 / 4 adverse events were not common, included neutropenia (17.6%), fatigue (11.8%), anemia (11.8%), leukopenia (11.8%), nausea (5.9%), peripheral neuropathy (5.9%), diarrhea (5.9%), and thrombocytopenia (5.9%). No treatment-related deaths occurred.ConclusionNab-paclitaxel/ gemcitabine combination chemotherapy is comparatively effective in the treatment of STS, demonstrates low toxicity, and is worthy of further study.
Project description:Albumin-bound paclitaxel (nab-paclitaxel) is a solvent-free formulation of paclitaxel that was initially developed more than a decade ago to overcome toxicities associated with the solvents used in the formulation of standard paclitaxel and to potentially improve efficacy. Nab-paclitaxel has demonstrated an advantage over solvent-based paclitaxel by being able to deliver a higher dose of paclitaxel to tumors and decrease the incidence of serious toxicities, including severe allergic reactions. To date, nab-paclitaxel has been indicated for the treatment of three solid tumors in the USA. It was first approved for the treatment of metastatic breast cancer in 2005, followed by locally advanced or metastatic non-small-cell lung cancer in 2012, and most recently for metastatic pancreatic cancer in 2013. Nab-paclitaxel is also under investigation for the treatment of a number of other solid tumors. This review highlights key clinical efficacy and safety outcomes of nab-paclitaxel in the solid tumors for which it is currently indicated, discusses ongoing trials that may provide new data for the expansion of nab-paclitaxel's indications into other solid tumors, and provides a clinical perspective on the use of nab-paclitaxel in practice.
Project description:Hydrogels are excellent candidates for the sustained local delivery of anticancer drugs, as they possess tunable physicochemical characteristics that enable to control drug release kinetics and potentially tackle the problem of systemic side effects in traditional chemotherapeutic delivery. Yet, current systems often involve complicated manufacturing or covalent bonding processes that are not compatible with regulatory or market reality. Here, we developed a novel gelatin methacryloyl (GelMA)-based drug delivery system (GelMA-DDS) for the sustained local delivery of paclitaxel-based Abraxane®, for the prevention of local breast cancer recurrence following mastectomy. GelMA-DDS readily encapsulated Abraxane® with a maximum of 96% encapsulation efficiency. The mechanical properties of the hydrogel system were not affected by drug loading. Tuning of the physical properties, by varying GelMA concentration, allowed tailoring of GelMA-DDS mesh size, where decreasing the GelMA concentration provided overall more sustained cumulative release (significant differences between 5%, 10%, and 15%) with a maximum of 75% over three months of release, identified to be released by diffusion. Additionally, enzymatic degradation, which more readily mimics the in vivo situation, followed a near zero-order rate, with a total release of the cargo at various rates (2-14 h) depending on GelMA concentration. Finally, the results demonstrated that Abraxane® delivery from the hydrogel system led to a dose-dependent reduction of viability, metabolic activity, and live-cell density of triple-negative breast cancer cells in vitro. The GelMA-DDS provides a novel and simple approach for the sustained local administration of anti-cancer drugs for breast cancer recurrence.
Project description:BackgroundBlood-brain barrier (BBB) disruption after stroke is closely associated with brain tissue edema and neuronal injury, which requires accurate assessment. However, there is a lack of appropriate BBB imaging modality in vivo. As albumin in the blood could cross the damaged BBB into brain tissue after stroke, it serves as a biomarker for BBB disruption. Therefore, we aimed to develop an albumin-seeking near-infrared (NIR) probe to assess BBB disruption in stroke.ResultsWe proposed a chemoselective strategy for seeking albumin with NIR dyes and identified an optimal probe to evaluate BBB disruption in stroke. The probe combined a NIR fluorescent dye with inherent albumin-targeting moieties and exhibited high affinity and selectivity for binding to albumin. Using a mouse stroke model, the probe displayed a high-resolution visualization of the location and extent of BBB disruption in vivo and correlated well with BBB leakage measured by Evans blue ex vivo. A dual-channel NIR-II imaging was successfully used to simultaneously assess BBB disruption and cerebral perfusion after stroke. Furthermore, we applied this method to dynamically evaluate the BBB disruption process and reperfusion of thrombolytic therapy in a stroke model in real time, which showed excellent application value.ConclusionsWe developed an albumin-seeking NIR probe that accurately evaluated BBB disruption in a safe, non-invasive and real-time manner in various stroke models, and has a great potential guiding stroke treatment in a real-time manner.
Project description:Blood-brain barrier dysfunction (BBBD) and accumulation of senescent astrocytes occur during brain aging and contribute to neuroinflammation and disease. Here, we explored the relationship between these two age-related events, hypothesizing that chronic hippocampal exposure to the blood-borne protein serum albumin could induce stress-induced premature senescence (SIPS) in astrocytes via transforming growth factor beta 1 (TGFβ) signaling. We found that 1 week of albumin exposure significantly increased TGFβ signaling and senescence marker expression in cultured rat hippocampal astrocytes. These changes were preventable by pharmacological inhibition of the type I TGFβ receptor (TGFβR) ALK5. To study these effects in vivo, we utilized an animal model of BBBD in which albumin was continuously infused into the lateral ventricles of adult mice. Consistent with our in vitro results, 1 week of albumin infusion significantly increased TGFβ signaling activation and the burden of senescent astrocytes in hippocampal tissue. Pharmacological inhibition of ALK5 TGFβR or conditional genetic knockdown of astrocytic TGFβR prior to albumin infusion was sufficient to prevent albumin-induced astrocyte senescence. Together, these results establish a link between TGFβ signaling activation and astrocyte senescence and suggest that prolonged exposure to serum albumin due to BBBD can trigger these phenotypic changes.
Project description:Blood-brain barrier (BBB) permeability can be measured by the ratio of albumin in cerebrospinal fluid (CSF) and blood and by dynamic contrast-enhanced MRI (DCEMRI). Albumin is a large molecule measured in CSF and blood to form the albumin index (Qalb), which is a global measure of BBB permeability, while the smaller Gadolinium molecule measures regional transfer (Ktrans); few studies have directly compared them in the same patients. We used both methods as part of a study of mechanisms of white matter injury in patients with different forms of dementia. In addition, we also measured biomarkers for inflammation, including proteases, angiogenic growth factors, and cytokines, and correlated them with the BBB results. We found that there was no correlation between Qalb and Ktrans. The Qalb was associated with the matrix metalloproteinases (MMP-2, MMP-3, and MMP-10), the angiogenic factors (VEGF-C and PlGF), and the cytokines (IL-6, IL-8 and TNF-α). On the other hand, Ktrans was associated with the diffusion measures, mean free water and PSMD, which indicate white matter injury. Our results show that the Qalb and Ktrans measure different aspects of BBB permeability, with albumin being a measure of inflammatory BBB opening and Ktrans indicating white matter injury.