Liposomes Coloaded with Elacridar and Tariquidar To Modulate the P-Glycoprotein at the Blood-Brain Barrier

Using Immunoliposomes as Carriers to Enhance the Therapeutic Effectiveness of Macamide N-3-Methoxybenzyl-Linoleamide

BACKGROUND/OBJECTIVES

Epilepsy is one of the most common chronic neurological disorders, characterized by alterations in neuronal electrical activity that result in recurrent seizures and involuntary body movements. Anticonvulsants are the primary treatment for this condition, helping patients improve their quality of life. However, the development of new drugs with fewer side effects and greater economic accessibility remains a key focus in nanomedicine. Macamides, secondary metabolites derived from Maca (Lepidium meyenii), represent a promising class of novel drugs with diverse therapeutic applications, particularly in the treatment of neurological disorders.

METHODS

In this study, we optimized the potential of the macamide N-3-methoxybenzyl-linoleamide (3-MBL) as an anticonvulsant agent through its encapsulation in PEGylated liposomes conjugated with OX26 F(ab')2 fragments.

RESULTS

These immunoliposomes exhibited a size of 120.52 ± 9.46 nm and a zeta potential of -8.57 ± 0.80 mV. Furthermore, in vivo tests using a pilocarpine-induced status epilepticus model revealed that the immunoliposomes provided greater efficacy against epileptic seizures compared to the free form of N-3-methoxybenzyl-linoleamide at the same dose. Notably, the observed anticonvulsant effect was comparable to that of carbamazepine, a traditional FDA-approved antiepileptic drug.

CONCLUSIONS

This pioneering work employs liposomal nanocarriers to deliver macamides to the brain, aiming to set a new standard for the use of modified liposomes in anticonvulsant epilepsy treatment.

Liposomes against Alzheimer's Disease: Current Research and Future Prospects

Alzheimer's disease, the most common neurodegenerative disease, affects more than 60 million people worldwide, a number that is estimated to double by 2050. Alzheimer's disease is characterized by progressive memory loss, the impairment of behavior, and mood changes, as well as the disturbed daily routine of the patient. Although there are some active molecules that can be beneficial by halting the progression of the disease, the blood-brain barrier and other physiological barriers hinder their delivery and, consequently, the appropriate management of the disease. Therefore, drug delivery systems that effectively target and overcome the blood-brain barrier to reach the targeted brain area would improve treatment effectiveness. Liposomes are lipophilic carriers that consist of a phospholipid bilayer structure, simulating the physiological lipidic layer of the blood-brain barrier and enabling better delivery of the drug to the brain. Given that pure liposomes may have less targeting affinity than functionalized liposomes, modification with groups such as lactoferrin, poly(ethylene glycol), and transferrin may improve specificity. In this mini-review, we summarize the literature on the use of liposomes for the treatment of Alzheimer's disease, focusing on the functionalization moieties of liposomes. In addition, challenges in brain delivery are also discussed.

Recent Advancements in Liposome-Targeting Strategies for the Treatment of Gliomas: A Systematic Review

Malignant tumors represent some of the most intractable diseases that endanger human health. A glioma is a tumor of the central nervous system that is characterized by severe invasiveness, blurred boundaries between the tumor and surrounding normal tissue, difficult surgical removal, and high recurrence. Moreover, the blood-brain barrier (BBB) and multidrug resistance (MDR) are important factors that contribute to the lack of efficacy of chemotherapy in treating gliomas. A liposome is a biofilm-like drug delivery system with a unique phospholipid bilayer that exhibits high affinities with human tissues/organs (e.g., BBB). After more than five decades of development, classical and engineered liposomes consist of four distinct generations, each with different characteristics: (i) traditional liposomes, (ii) stealth liposomes, (iii) targeting liposomes, and (iv) biomimetic liposomes, which offer a promising approach to promote drugs across the BBB and to reverse MDR. Here, we review the history, preparatory methods, and physicochemical properties of liposomes. Furthermore, we discuss the mechanisms by which liposomes have assisted in the diagnosis and treatment of gliomas, including drug transport across the BBB, inhibition of efflux transporters, reversal of MDR, and induction of immune responses. Finally, we highlight ongoing and future clinical trials and applications toward further developing and testing the efficacies of liposomes in treating gliomas.

Codelivery of doxorubicin and elacridar to target both liver cancer cells and stem cells by polylactide-co-glycolide/d-alpha-tocopherol polyethylene glycol 1000 succinate nanoparticles

Purpose

Liver cancer is the third leading cause of cancer-related deaths worldwide. Liver cancer stem cells (LCSCs) are a subpopulation of cancer cells that are responsible for the initiation, progression, drug resistance, recurrence, and metastasis of liver cancer. Recent studies have suggested that the eradication of both LCSCs and liver cancer cells is necessary because the conversion of cancer stem cells (CSCs) to cancer cells occasionally occurs. As ATP-binding cassette (ABC) transporters are overexpressed in both CSCs and cancer cells, combined therapies using ABC transporter inhibitors and chemotherapy drugs could show superior therapeutic efficacy in liver cancer. In this study, we developed poly(lactide-co-glycolide)/d-alpha-tocopherol polyethylene glycol 1000 succinate nanoparticles to accomplish the simultaneous delivery of an optimized ratio of doxorubicin (DOX) and elacridar (ELC) to target both LCSCs and liver cancer cells.

Methods

Median-effect analysis was used for screening of DOX and ELC for synergy in liver cancer cells (HepG2 cells) and LCSCs (HepG2 tumor sphere [HepG2-TS]). Then, nanoparticles loaded with DOX and ELC at the optimized ratio (NDEs) were prepared by nanoprecipitation method. The cytotoxicity and colony and tumor sphere formation ability of nanoparticles were investigated in vitro, and the tissue distribution and antitumor activity of nanoparticles were evaluated in vivo.

Results

We demonstrated that a DOX/ELC molar ratio of 1:1 was synergistic in HepG2 cells and HepG2-TS. NDEs were shown to exhibit significantly increased cytotoxic effects against both HepG2 and HepG2-TS compared with DOX-loaded nanoparticles (NDs) or ELC-loaded nanoparticles (NEs) in vitro. In vivo studies demonstrated that the nanoparticles exhibited better tumor targeting, with NDE showing the strongest antitumor activity with lower systemic toxicity.

Conclusion

These results suggested that NDE represented a promising combination therapy against liver cancer by targeting both liver cancer cells and CSCs.

P-glycoprotein Restricts Ocular Penetration of Loperamide across the Blood-Ocular Barriers: a Comparative Study in Mdr1a Knock-out and Wild Type Sprague Dawley Rats

The current research was undertaken to determine the existence and magnitude of P-glycoprotein (P-gp) expression on the blood-ocular barriers by studying the ocular penetration of loperamide, a specific P-gp substrate, in P-gp (Mdr1a) knock-out (KO) and wild type (WT) Sprague Dawley rats. A clear, stable, sterile solution of loperamide (1 mg/mL), for intravenous administration, was formulated and evaluated. Ocular distribution was studied in P-gp KO and WT rats following intravenous administration of loperamide (at two doses). The drug levels in plasma, aqueous humor (AH), and vitreous humor (VH) samples were determined with the aid of UHPLC-Q-TOF-MS/MS, and the AH/plasma (D _AH ) and VH/plasma (D _VH ) distribution ratios were estimated. Electroretinography (ERG), ultrastructural analyses, and histology studies were carried out, in both KO and WT rats, to detect any drug-induced functional and/or structural alterations in the retina. Dose-related loperamide levels were observed in the plasma of both WT and KO rats. The loperamide concentrations in the AH and VH of KO rats were significantly higher compared to that observed in the WT rats, at the lower dose. However, a marked increase in the D _AH and D _VH was noted in the KO rats. ERG, ultrastructure, and histology studies did not indicate any drug-induced toxic effects in the retina under the test conditions. The results from these studies demonstrate that P-gp blocks the penetration of loperamide into the ocular tissues from the systemic circulation and that the effect is more pronounced at lower plasma loperamide concentrations.

Retina Compatible Interactions and Effective Modulation of Blood Ocular Barrier P-gp Activity by Third-Generation Inhibitors Improve the Ocular Penetration of Loperamide

Effective drug delivery to the deeper ocular tissues remains an unresolved conundrum mainly due to the expression of multidrug resistance efflux proteins, besides tight junction proteins, in the blood ocular barriers (BOBs). Hence, the purpose of the current research was to investigate the ability of the third-generation efflux protein inhibitors, elacridar (EQ), and tariquidar (TQ), to diminish P-glycoprotein (P-gp) mediated efflux transport of loperamide (LOP), a P-gp substrate, across the BOB in Sprague Dawley rats. Initially, Western blot analysis confirmed the expression of P-gp in the iris-ciliary bodies and the retina choroid in the wild type rats. Next, the ocular distribution of LOP, in the presence and absence of EQ/TQ (at 2 doses), was evaluated. The significantly higher aqueous humor/plasma (D_AH) and vitreous humor (VH)/plasma (D_VH) distribution ratios of LOP in the rats pretreated with EQ or TQ demonstrated effective inhibition of P-gp activity in the BOB. Interestingly, the modulation of P-gp activity by EQ/TQ was more pronounced at the lower dose. The normal functioning and architecture of the retina, as indicated by electroretinography studies, confirmed the cytocompatibility of LOP and EQ/TQ interactions at the doses tested.

On Chip Bioelectric Impedance Spectroscopy Reveals the Effect of P-Glycoprotein Efflux Pumps on the Paracellular Impedance of Tight Junctions at the Blood-Brain Barrier

Bioelectric impedance spectroscopy was used to elucidate the influence of P-gp efflux pumps on the kinetics of tight junction down-regulation in confluent monolayers of Madine Darby Canine Kidney Epithelial Cells (MDCK) following administration of phenylarsine oxide (PAO), a molecule that inhibits protein tyrosine phosphatases (PTP) and induces matrix metalloproteinase activity. Matrix metalloproteinases (MMPs) and phosphatase inhibitors induce modification of occludin tight junction proteins critical for the proper function of the blood-brain barrier. The addition of PAO to MDCKII cell lines resulted in a dramatic decrease in monolayer resistance. In contrast, MDCKII-MDR1 cells transfected with the MDR1 gene treated with PAO showed an initial decrease in monolayer resistance followed by a partial recovery and subsequent decrease. This resistance decay reversal was suppressed with the addition of the P-glycoprotein (P-gp) pump inhibitor elacridar, and is attributed to PAO efflux. These results illustrate impedance spectroscopy can be used to characterize the competing kinetics of efflux and down-regulation of tight junctions. In addition, the resistance decay reversal effect can be used to evaluate P-gp pump inhibitor efficacy.

Co-encapsulation of borneol and paclitaxel by liprosomes improved anti-tumor effect in a xenografted glioma model

In this study, a borneol (BOR) and paclitaxel (PTX) co-encapsulated lipid–protein nanocomplex (BP–liprosome) was developed for the treatment of brain glioma.