Transient Opening of the Blood-Brain Barrier by Vasoactive Peptides to Increase CNS Drug Delivery: Reality Versus Wishful Thinking?

Glioma stem cells: drivers of tumor progression and recurrence

Glioma, a common malignancy of the central nervous system, attracts significant clinical attention due to its poor prognosis. Glioma stem cells (GSCs), characterized by stem-like properties and substantial heterogeneity, play a crucial role in tumor initiation, progression, and potential recurrence. Moreover, through complex interaction mechanisms, they contribute to the challenges associated with treatment. This review seeks to explore the distinctive characteristics and underlying mechanisms of GSCs, aiming to provide novel theoretical insights and practical strategies for precision therapy in glioma.

Clinical efficacy and hemodynamic effects of levosimendan in cardiac surgery patients after surgery

OBJECTIVE

To investigate the therapeutic effect of levosimendan on hemodynamics in patients undergoing major cardiac surgery and presenting with acute postoperative heart failure.

METHODS

The subjects of the study were 160 patients with severe cardiac conditions who underwent surgery and had acute heart failure. Eighty cases each were assigned to the research and control groups using a random number table. Document the general patient data for each of the two groups; compare the clinical outcomes of the two groups. The hemodynamic states of the two groups were compared both before and after therapy. 48 h after surgery, echocardiography was performed in both groups to determine cardiac function. 48 h after surgery, N-terminal pro-brain B-type natriuretic peptide (NT-Pro-BNP) levels were compared between the two groups.

RESULTS

The overall effective rate was significantly higher in the research group (92.5%) compared to the control group (76.25%, P < 0.05). Post-treatment, the research group demonstrated a significant reduction in CVP (9.25 ± 2.11 cmH2O vs. 11.36 ± 3.08 cmH2O, P < 0.001), heart rate (100.30 ± 8.69 bpm vs. 105.74 ± 7.69 bpm, P < 0.001), and lactic acid levels (1.68 ± 0.59 mmol/L vs. 2.69 ± 0.55 mmol/L, P < 0.001). The research group also showed improvements in SBP (117.23 ± 8.74 mmHg vs. 113.25 ± 7.55 mmHg, P = 0.002) and urine output (4.21 ± 1.76 mL/kg/h vs. 3.65 ± 1.23 mL/kg/h, P = 0.021). Cardiac function indicators 48 h after surgery indicated a higher LVEF (55.21 ± 8.04% vs. 47.18 ± 6.60%, P < 0.001) and lower LVEDVi and LVESVi in the research group (P < 0.001 for both). NT-Pro-BNP levels were significantly lower in the research group (6010.19 ± 1208.52 pg/mL vs. 9663.21 ± 2391.34 pg/mL, P < 0.001). The incidence of complications was lower in the research group (5% vs. 22.5%, P = 0.001).

CONCLUSION

Cardiac surgery patients are prone to complications with acute heart failure after surgery. Treatment with levosimendan can significantly improve clinical efficacy and reduce complications. It can also effectively improve patients' cardiac function and promote hemodynamic stability.

Assessing the dose of regadenoson required to transiently alter blood-brain barrier integrity in patients with infiltrating gliomas

Background

The blood-brain barrier (BBB) severely limits the delivery of therapeutic agents to the brain. Regadenoson, a Food and Drug Administration-approved adenosine A2 agonist, transiently increases BBB permeability in rodents to a 70 kDa dextran. This multi-institutional, NIH-funded study examined regadenoson's ability to transiently alter BBB permeability in patients with gliomas.

Methods

Adults with supratentorial gliomas at low risk for regadenoson complications were treated with 1 of the 7 dose levels known to be safe in humans. Successful BBB disruption was defined as a 10-fold increase in vascular permeability (K trans ) relative to historic benchmarks. This was assessed by dynamic contrast-enhanced perfusion on magnetic resonance imaging in normal-appearing white matter (NAWM) changes in NAWM and non-enhancing tumors were also quantified using contrast-enhanced T1 subtraction maps.

Results

Seven patients <45 years old with low-grade gliomas were accrued before the study was prematurely closed. Regadenoson was well tolerated. Following regadenoson, K trans in NAWM did not reach the targeted K trans threshold (0.04 min-1). Normalized subtraction maps of contrast-enhanced T1-weighted MR signal intensity in NAWM did increase an average of 74% ± 22% (P = .016) after regadenoson.

Conclusions

No dose of regadenoson significantly elevated K trans in NAWM. However, the subtraction maps suggest that regadenoson may lead to a measurable change in gadolinium flux. This coupled with strong preclinical data suggests further investigation is warranted. Noninvasive quantification of BBB permeability in patients is feasible and could evaluate different regadenoson schedules, combination therapies, and other approaches to modify BBB permeability which is critical to improving outcomes in patients with brain tumors.

Clinical Trial Registration

NCI Protocol #: Adult brain tumor consortium 1804, ClinicalTrials.gov Identifier: NCT03971734, Agent(s): Regadenoson, NSC # 811401, commercially available.

Evidence for interictal blood-brain barrier dysfunction in people with epilepsy

OBJECTIVE

Interictal blood-brain barrier dysfunction in chronic epilepsy has been demonstrated in animal models and pathological specimens. Ictal blood-brain barrier dysfunction has been shown in humans in vivo using an experimental quantitative magnetic resonance imaging (MRI) protocol. Here, we hypothesized that interictal blood-brain barrier dysfunction is also present in people with drug-resistant epilepsy.

METHODS

Thirty-nine people (21 females, mean age at MRI ± SD = 30 ± 8 years) with drug-resistant epilepsy were prospectively recruited and underwent interictal T1-relaxometry before and after administration of a paramagnetic contrast agent. Likewise, quantitative T1 was acquired in 29 people without epilepsy (12 females, age at MRI = 48 ± 18 years). Quantitative T1 difference maps were calculated and served as a surrogate imaging marker for blood-brain barrier dysfunction. Values of quantitative T1 difference maps inside hemispheres ipsilateral to the presumed seizure onset zone were then compared, on a voxelwise level and within presumed seizure onset zones, to the contralateral side of people with epilepsy and to people without epilepsy.

RESULTS

Compared to the contralateral side, ipsilateral T1 difference values were significantly higher in white matter (corrected p < .05), gray matter (uncorrected p < .05), and presumed seizure onset zones (p = .04) in people with epilepsy. Compared to people without epilepsy, significantly higher T1 difference values were found in the anatomical vicinity of presumed seizure onset zones (p = .004). A subgroup of people with hippocampal sclerosis demonstrated significantly higher T1 difference values in the ipsilateral hippocampus and in regions strongly interconnected with the hippocampus compared to people without epilepsy (corrected p < .01). Finally, z-scores reflecting the deviation of T1 difference values within the presumed seizure onset zone were associated with verbal memory performance (p = .02) in people with temporal lobe epilepsy.

SIGNIFICANCE

Our results indicate a blood-brain barrier dysfunction in drug-resistant epilepsy that is detectable interictally in vivo, anatomically related to the presumed seizure onset zone, and associated with cognitive deficits.

Next-generation agents for fluorescence-guided glioblastoma surgery

Glioblastoma is a fast-growing and aggressive form of brain cancer. Even with maximal treatment, patients show a low median survival and are often subjected to a high recurrence incidence. The currently available treatments require multimodal management, including maximal safe surgical resection, followed by radiation and chemotherapy. Because of the infiltrative glioblastoma nature, intraoperative differentiation of cancer tissue from normal brain parenchyma is very challenging, and this accounts for the low rate of complete tumor resection. For these reasons, clinicians have increasingly used various intraoperative adjuncts to improve surgical results, such as fluorescent agents. However, most of the existing fluorophores show several limitations such as poor selectivity, photostability, photosensitization and high costs. This could limit their application to successfully improve glioblastoma resection. In the present perspective, we highlight the possibility to develop next-generation fluorescent tools able to more selectively label cancer cells during surgical resection.

Brain delivery enabled by transient blood-brain barrier disruption induced by regadenoson: a PET imaging study

BACKGROUND

Regadenoson, an agonist of adenosine A2 receptors, enables transient blood-brain barrier (BBB) disruption. The relevance of regadenoson as a pharmacological strategy for brain delivery was investigated using in vivo PET imaging in rats.

RESEARCH DESIGN AND METHODS

Kinetic modeling of brain PET data was performed to estimate the impact of regadenoson (0.05 mg.kg-1, i.v.) on BBB permeation compared with control rats (n = 4-6 per group). Three radiolabeled compounds of different sizes, which do not cross the intact BBB, were tested.

RESULTS

Regadenoson significantly increased the BBB penetration (+116 ± 13%, p < 0.001) of [18F]2-deoxy-2-fluoro-D-sorbitol ([18F]FDS, MW = 183 Da), a small-molecule marker of BBB permeability. The magnitude of the effect was different across brain regions, with a maximum increase in the striatum. Recovery of BBB integrity was observed 30 min after regadenoson injection. Regadenoson also increased the brain penetration (+72 ± 45%, p < 0.05) of a radiolabeled nanoparticle [89Zr]AGuIX (MW = 9 kDa). However, the brain kinetics of a monoclonal antibody ([89Zr]mAb, MW = 150 kDa) remained unchanged (p > 0.05).

CONCLUSIONS

PET imaging showed the features and limitations of BBB disruption induced by regadenoson in terms of extent, regional distribution, and reversibility. Nevertheless, regadenoson enables the brain delivery of small molecules or nanoparticles in rats.

Blood-Brain Barrier Disruption for the Treatment of Primary Brain Tumors: Advances in the Past Half-Decade

PURPOSE OF REVIEW

To review relevant advances in the past half-decade in the treatment of primary brain tumors via modification of blood-brain barrier (BBB) permeability.

RECENT FINDINGS

BBB disruption is becoming increasingly common in the treatment of primary brain tumors. Use of mannitol in BBB disruption for targeted delivery of chemotherapeutics via superselective intra-arterial cerebral infusion (SIACI) is the most utilized strategy to modify the BBB. Mannitol is used in conjunction with chemotherapeutics, oligonucleotides, and other active agents. Convection-enhanced delivery has become an attractive option for therapeutic delivery while bypassing the BBB. Other technologic innovations include laser interstitial thermal therapy (LITT) and focused ultrasound (FUS) which have emerged as prime modalities to directly target tumors and cause significant local BBB disruption. In the past 5 years, interest has significantly increased in studying modalities to disrupt the BBB in primary brain tumors to enhance treatment responses and improve clinical outcomes.

Nanoparticles loaded with natural medicines for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that disrupts cognitive function and severely affects the quality of life. Existing drugs only improve cognitive function and provide temporary relief of symptoms but do not stop or delay disease progression. Recently, natural medicines, especially Chinese herbal medicines, have gained attention in the treatment of AD due to their antioxidant, anti-inflammatory, and neuroprotective effects. However, conventional oral dosage forms lack brain specificity and have side effects that lead to poor patient compliance. Utilizing nanomedicine is a promising approach to improve brain specificity, bioavailability, and patient compliance. This review evaluates recent advances in the treatment of AD with nanoparticles containing various natural medicines. This review highlights that nanoparticles containing natural medicines are a promising strategy for the treatment of AD. It is believed that this technology can be translated into the clinic, thereby providing opportunities for AD patients to participate in social activities.

Engineered nanomaterials that exploit blood-brain barrier dysfunction fordelivery to the brain

The blood-brain barrier (BBB) is a highly regulated physical and functional boundarythat tightly controls the transport of materials between the blood and the brain. There is an increasing recognition that the BBB is dysfunctional in a wide range of neurological disorders; this dysfunction can be symptomatic of the disease but can also play a role in disease etiology. BBB dysfunction can be exploited for the delivery of therapeutic nanomaterials. Forexample, there can be a transient, physical disruption of the BBB in diseases such as brain injury and stroke, which allows temporary access of nanomaterials into the brain. Physicaldisruption of the BBB through external energy sources is now being clinically pursued toincrease therapeutic delivery into the brain. In other diseases, the BBB takes on new properties that can beleveraged by delivery carriers. For instance, neuroinflammation induces the expression ofreceptors on the BBB that can be targeted by ligand-modified nanomaterials and theendogenous homing of immune cells into the diseased brain can be hijacked for the delivery ofnanomaterials. Lastly, BBB transport pathways can be altered to increase nanomaterial transport. In this review, we will describe changes that can occur in the BBB in disease, and how these changes have been exploited by engineered nanomaterials forincreased transport into the brain.