Enhanced bioavailability of orally administered flurbiprofen by combined use of hydroxypropyl-cyclodextrin and poly(alkyl-cyanoacrylate) nanoparticles.

Flurbiprofen was formulated into nanoparticle suspension to improve its oral bioavailability. Hydroxypropyl-ß-cyclodextrin inclusion-flurbiprofen complex (HP-ß-CD-FP) was prepared, then incorporating this complex into poly(alkyl-cyanoacrylate) (PACA) nanoparticles. HP-ß-CD-FP-PACA nanoparticle was prepared by the emulsion solvent polymerization method. The zeta potential was -26.8 mV, the mean volume particle diameter was 134 nm, drug encapsulation efficiency was 53.3 ± 3.6 % and concentration was 1.5 mg/mL. The bioavailability of flurbiprofen from optimized nanoparticles was assessed in male Wistar rats at a dose of 15 mg/kg. As compared to the flurbiprofen suspension, 211.6 % relative bioavailability was observed for flurbiprofen nanoparticles. The reduced particle size and increased surface area may contribute to improve oral bioavailability of flurbiprofen.

Endocytosis of ATB0,+(SLC6A14)-targeted liposomes for drug delivery and its therapeutic application for pancreatic cancer.

Background: SLC6A14 (ATB0,+), a Na+/Cl-coupled transporter for neutral/cationic amino acids, is overexpressed in many cancers; It has been investigated as a target for improved liposomal drug delivery to treat liver cancer.Research design and methods: Here we explored the mechanism of ATB0,+-mediated entry of such liposomes. As ATB0,+ is highly expressed in pancreatic cancer, we also examined the therapeutic utility of ATB0,+-targeted liposomal drug delivery to treat this cancer.Results: The uptake of lysine-conjugated liposomes (LYS-LPs) was greater in ATB0,+-positive MCF7 cells. The uptake process consisted of two steps: binding and internalization. The binding of LYS-LPs to MCF7 cells was higher than that of bare liposomes, and the process was dependent on Na+ and Cl-, and inhibitable by ATB0,+ substrates or blocker. In contrast, the internalization step was independent of lysine. The cellular entry of LYS-LPs facilitated by ATB0,+ occurred via endocytosis with transient endosomal degradation of ATB0,+ protein with subsequent recovery. Moreover, LYS-LPs also enhanced the uptake and cytotoxicity of gemcitabine in these cells in an ATB0,+-dependent manner.Conclusions: We conclude that ATB0,+ could be exploited for targeted drug delivery in the form of lysine-conjugated liposomes and that the approach represents a novel strategy for enhanced pancreatic cancer therapy.

Dual targeting of l-carnitine-conjugated nanoparticles to OCTN2 and ATB0,+ to deliver chemotherapeutic agents for colon cancer therapy.

l-Carnitine, obligatory for oxidation of fatty acids, is transported into cells by the Na+-coupled transporter OCTN2 and the Na+/Cl--coupled transporter ATB0,+. Here we investigated the potential of L-carnitine-conjugated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (LC-PLGA NPs) to deliver chemotherapeutic drugs into cancer cells by targeting the nanoparticles to both OCTN2 and ATB0,+. The cellular uptake of LC-PLGA NPs in the breast cancer cell line MCF7 and the colon cancer cell line Caco-2 was increased compared to unmodified nanoparticles, but decreased in the absence of co-transporting ions (Na+ and/or Cl-) or in the presence of competitive substrates for the two transporters. Studies with fluorescently labeled nanoparticles showed their colocalization with both OCTN2 and ATB0,+, confirming the involvement of both transporters in the cellular uptake of LC-PLGA NPs. As the expression levels of OCTN2 and ATB0,+ are higher in colon cancer cells than in normal colon cells, LC-PLGA NPs can be used to deliver chemotherapeutic drugs selectively into cancer cells for colon cancer therapy. With 5-fluorouracil-loaded LC-PLGA NPs, we were able to demonstrate significant increases in the uptake efficiency and cytotoxicity in colon cancer cells that were positive for OCTN2 and ATB0,+. In a 3D spheroid model of tumor growth, LC-PLGA NPs showed increased uptake and enhanced antitumor efficacy. These findings indicate that dual-targeting LC-PLGA NPs to OCTN2 and ATB0,+ has great potential to deliver chemotherapeutic drugs for colon cancer therapy. Dual targeting LC-PLGA NPs to OCTN2 and ATB0,+ can selectively deliver chemotherapeutics to colon cancer cells where both transporters are overexpressed, preventing targeting to normal cells and thus avoiding off-target side effects.

ATB0,+ transporter-mediated targeting delivery to human lung cancer cells via aspartate-modified docetaxel-loading stealth liposomes.

Tumor cells have an increased demand for amino acids to support their rapid growth and malignant metastasis. Transfer of amino acids across plasma membranes depends on several amino acid transporters that are highly upregulated in tumor cells and are promising targets for tumor cell-selective therapy. In this study, stealth liposomal systems functionalized with aspartate-polyoxyethylene stearate conjugate (APS) were developed for transporter-mediated targeted delivery to ATB0,+, which is overexpressed human lung cells. The resultant ATB0,+-targeting liposomes (APS-Lips) consisted of a liposome core and the surface coverage of the APS modifier had an optimized density of 10%. APS-Lips had a uniform particle size distribution and high encapsulation efficiency of docetaxel (DTX, >80%). APS modification had a negligible effect on the DTX release from liposomes. Compared with Taxotere and unmodified liposomes, APS-Lips showed increased intracellular delivery and antitumor potency against human lung cells. Furthermore, competitive endocytosis studies showed that the cellular uptake of APS-Lips was notably decreased in the presence of glycine, a typical substrate of ATB0,+, and was increased through adhesion to the cell membrane via transporter-substrate interactions. Finally, in vitro hemolysis and in vivo vascular irritation studies in rabbits confirmed the good blood compatibility and minimal vascular stimulation of the synthetic ATB0,+-targeting material APS. These results demonstrated that the aspartate-modified liposomes could be a promising nanocarrier for ATB0,+ transporter-mediated targeted drug delivery to treat lung cancer.

Cotransporting Ion is a Trigger for Cellular Endocytosis of Transporter-Targeting Nanoparticles: A Case Study of High-Efficiency SLC22A5 (OCTN2)-Mediated Carnitine-Conjugated Nanoparticles for Oral Delivery of Therapeutic Drugs.

OCTN2 (SLC22A5) is a Na+ -coupled absorption transporter for l-carnitine in small intestine. This study tests the potential of this transporter for oral delivery of therapeutic drugs encapsulated in l-carnitine-conjugated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (LC-PLGA NPs) and discloses the molecular mechanism for cellular endocytosis of transporter-targeting nanoparticles. Conjugation of l-carnitine to a surface of PLGA-NPs enhances the cellular uptake and intestinal absorption of encapsulated drug. In both cases, the uptake process is dependent on cotransporting ion Na+ . Computational OCTN2 docking analysis shows that the presence of Na+ is important for the formation of the energetically stable intermediate complex of transporter-Na+ -LC-PLGA NPs, which is also the first step in cellular endocytosis of nanoparticles. The transporter-mediated intestinal absorption of LC-PLGA NPs occurs via endocytosis/transcytosis rather than via the traditional transmembrane transport. The portal blood versus the lymphatic route is evaluated by the plasma appearance of the drug in the control and lymph duct-ligated rats. Absorption via the lymphatic system is the predominant route in the oral delivery of the NPs. In summary, LC-PLGA NPs can effectively target OCTN2 on the enterocytes for enhancing oral delivery of drugs and the critical role of cotransporting ions should be noticed in designing transporter-targeting nanoparticles.

Transporter occluded-state conformation-induced endocytosis: Amino acid transporter ATB0,+-mediated tumor targeting of liposomes for docetaxel delivery for hepatocarcinoma therapy.

Rapidly proliferating tumor cells upregulate specific amino acid transporters, which hold great potential for tumor-selective drug delivery. Published reports have focused primarily on blocking these transporters as a means of starving the tumor cells of amino acids, but their potential in drug delivery remains understudied. In the present study, we developed liposomes functionalized with lysine and polyoxyethylene stearate conjugate (LPS) to interact with ATB0,+, an amino acid transporter overexpressed in hepatocarcinoma and the liver cancer cell line HepG2. The LPS modified liposomes (LPS-Lips) were ~100nm in size and exhibited high drug encapsulation efficiency as 94.7%. The uptake of LPS-Lips in HepG2 cells was dependent on Na+ and Cl-. Molecular dynamic simulation showed that a sustained occluded state of the transporter upon binding to co-transported ions was formed and LPS-Lips triggered the cellular internalization of liposomes. We loaded these LPS-Lips with docetaxel and evaluated the potential of ATB0,+-mediated endocytosis of the drug-loaded LPS-Lips in HepG2 cells in vitro and in syngeneic mouse transplants in vivo. Compared with unmodified liposomes, which did not interact with ATB0,+, LPS-Lips exhibited the ability to deliver docetaxel more efficiently into tumor cells with consequent greater antitumor efficacy and less systemic toxicity. These studies provide first evidences that ATB0,+ can be used as a novel and effective target for drug delivery system in tumor cells using chemically modified liposomes for loading with chemotherapeutics and targeting them for the transporter-mediated endocytosis. As ATB0,+ is highly upregulated in several cancers, this approach holds potential for tumor-selective delivery of drugs to treat these cancer types.

Novel ophthalmic timolol meleate liposomal-hydrogel and its improved local glaucomatous therapeutic effect in vivo.

To overcome the limitations of common eye drops, the study developed a novel timolol mealate (TM) liposomal-hydrogel to enhance drug permeability and prolong residence time in the precorneal region, which achieved more effective local glaucomatous therapeutic effect. Firstly, TM liposome was prepared by an ammonium sulfate gradient-pH regulation method, which its entrapment efficiency reached up to 94% and its averaged particle size is 187 nm with narrow distribution. The corneal permeability through isolated rabbit cornea was measured by modified Franz-type diffusion cells. The results of trans-corneal penetration exhibited that the apparent permeability coefficients (P(app)) and the flow rates of steady state (J(ss)) of TM liposome was 1.50-fold higher than that of the commercialized eye drop, while TM liposome with 0.02% transcutol P was 2.19 times. In order to increase the retention time and improve the stability of liposome, we further developed a TM liposomal-hydrogel formulation by adding 1.0% HPMC K4M in TM liposome. The results showed an stability during a 120 days storage period than TM liposome. Precorneal retention study in vivo indicated that the optimal liposomal-hydrogel formulation had improved bioavailability and its retention time on rabbit corneal surface were significantly longer than that of pure liposomes or eye-drops. No obvious irritations to rabbit eyes were observed by histopathology microscopy after 7 days exposure.. Comparing to the eye drops, the TM liposomal-gel displayed prolonged therapeutic effect in cornea and greatly lowered the intraocular pressure IOP on the eyes of normal and glaucomatous pigmented rabbits.