Change in pharmacokinetic and pharmacodynamic behavior of gemcitabine in human tumor xenografts upon entrapment in vesicular phospholipid gels

Membrane-immobilized gemcitabine for cancer-targetable NK cell surface engineering

Although natural killer (NK) cell-based adoptive cell transfer (ACT) has shown promise in cancer immunotherapy, its efficacy against solid tumors is limited in the immunosuppressive tumor microenvironment (TME). Combinatorial therapies involving chemotherapeutic drugs such as gemcitabine (Gem) and NK cells have been developed to modulate the TME; however, their clinical application is constrained by low drug delivery efficiency and significant off-target toxicity. In this study, we developed cell membrane-immobilized Gem conjugates (i.e., lipid-Gem conjugates), designed to anchor seamlessly onto NK cell surfaces. Our modular-designed ex vivo cell surface engineeringmaterials comprise a lipid anchor for membrane immobilization, poly(ethylene glycol) to inhibit endocytosis, a disulfide bond as cleavable linker by glutathione (GSH) released during cancer cell lysis, and Gem for targeted sensitization. We demonstrated that the intrinsic properties of NK cells, such as proliferation and surface ligand availability, were preserved despite coating with lipid-Gem conjugates. Moreover, delivery of Gem prodrugs by lipid-Gem coated NK (GCNK) cells was shown to enhance antitumor efficacy against pancreatic cancer cells (PANC-1) through the following mechanisms: (1) NK cells recognized and attacked cancer cells, (2) intracellular GSH was leaked out from the lysed cancer cells, enabling cleavage of disulfide bond, (3) released Gem from the GCNK cells delivered to the target cells, (4) Gem upregulated MHC class I-related chain A and B on cancer cells, and (5) thereby activating NK cells led to enhance antitumor efficacy. The simultaneous co-delivery of membrane-immobilized Gem with NK cells could potentially facilitate both immune synapse-mediated cancer recognition and chemotherapeutic effects, offering a promising approach to enhance the anticancer efficacy of conventional ACTs.

Plectin-1-targeted recognition for enhancing comprehensive therapy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) poses a formidable challenge due to its aggressive nature and poor prognosis. Gemcitabine (Gem), a primary therapeutic option, functions by inhibiting DNA synthesis and promoting apoptosis, thereby impeding the progression of PDAC. However, Gem is hindered by suboptimal pharmacokinetics and efficacy. In response to these challenges, we have developed a nanoparticle (NP) designed for specific recognition of plectin-1 in PDAC cell membranes. The NPs encapsulate Gem while demonstrating pH-responsive drug release characteristics in the acidic tumor microenvironment. This targeted approach enhances local drug delivery while alleviating concerns about systemic toxicity. Furthermore, the NPs are enriched with indocyanine green (ICG), renowned for its strong photothermal effects, thereby further enhancing therapeutic outcomes. This study presents an innovative therapeutic strategy for PDAC based on a plectin-1-targeted recognition delivery approach. The approach is applied to enhance chemotherapy, combined with photothermal therapy (PTT), inducing apoptosis in PDAC cell lines and improving the pharmacokinetics of Gem. In conclusion, the delivery strategy based on plectin-1-targeted recognition shows promising preclinical prospects for enhancing therapeutic efficacy in PDAC, offering valuable insights for future clinical applications.

Oral Delivery of Photopolymerizable Nanogels Loaded with Gemcitabine for Pancreatic Cancer Therapy: Formulation Design, and in vitro and in vivo Evaluations

Background

Gemcitabine (GEM) faces challenges of poor oral bioavailability and extensive first-pass metabolism. Currently, only injectable formulations are available for clinical use. Hence, there is an urgent demand for the development of advanced, efficacious, and user-friendly dosage forms to maintain its status as the primary treatment for pancreatic ductal adenocarcinoma (PDAC). Nanogels (NGs) offer a novel oral drug delivery system, ideal for hydrophilic compounds like GEM. This study aims to develop NGs tailored for GEM delivery, with the goal of enhancing cellular uptake and gastrointestinal permeability for improved administration in PDAC patients.

Methods

We developed cross-linked NGs via photopolymerization of methacryloyl for drug delivery of GEM. We reveal characterization, cytotoxicity, and cellular uptake studies in Caco-2 and MIA PaCa-2 cells. In addition, studies of in vitro permeability and pharmacokinetics were carried out to evaluate the bioavailability of the drug.

Results

Our results show NGs, formed via photopolymerization of methacryloyl, had a spherical shape with a size of 233.91±7.75 nm. Gemcitabine-loaded NGs (NGs-GEM) with 5% GelMA exhibited efficient drug loading (particle size: 244.07±19.52 nm). In vitro drug release from NGs-GEM was slower at pH 1.2 than pH 6.8. Cellular uptake studies indicated significantly enhanced uptake in both MIA PaCa-2 and Caco-2 cells. While there was no significant difference in GEM's AUC and Cmax between NGs-GEM and free-GEM groups, NGs-GEM showed markedly lower dFdU content (10.07 hr∙μg/mL) compared to oral free-GEM (19.04 hr∙μg/mL) after oral administration (p<0.01), highlighting NGs' efficacy in impeding rapid drug metabolism and enhancing retention.

Conclusion

In summary, NGs enhance cellular uptake, inhibit rapid metabolic degradation of GEM, and prolong retention after oral administration. These findings suggest NGs-GEM as a promising candidate for clinical use in oral pancreatic cancer therapy.

Preparation of Nanosized Pharmaceutical Formulations by Dual Centrifugation

Dual centrifugation (DC) is an innovative in-vial homogenization and in-vial nanomilling technique that has been in use for the preparation of liposomes for more than one decade. Since then, DC has continuously been developed for preparing various liposomes and other lipid nanoparticles including emulsions and solid lipid nanoparticles (SLNs) as well as polymersomes and nanocrystals. Improvements in equipment technology have been achieved over the past decade, so that DC is now on its way to becoming the quasi-standard for the simple, fast, and aseptic production of lipid nanoparticles and nanocrystals in small and medium batch sizes, including the possibility of simple and fast formulation screening or bedside preparations of therapeutic nanoparticles. More than 68 publications in which DC was used to produce nanoparticles have appeared since then, justifying an initial review of the use of DC for pharmaceutical nanotechnology.

Development and Characterization of PEGDA Microneedles for Localized Drug Delivery of Gemcitabine to Treat Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) is one of the most belligerent types of breast cancer. While various modalities exist in managing/treating IBC, drug delivery using microneedles (MNs) is considered to be the most innovative method of localized delivery of anti-cancer agents. Localized drug delivery helps to treat IBC could limit their adverse reactions. MNs are nothing but small needle like structures that cause little or no pain at the site of administration for drug delivery via layers of the skin. The polyethylene glycol diacrylate (PEGDA) based MNs were fabricated by using three dimensional (3D) technology called Projection Micro-Stereo Lithography (PµSL). The fabricated microneedle patches (MNPs) were characterized and coated with a coating formulation comprising of gemcitabine and sodium carboxymethyl cellulose by a novel and inventive screen plate method. The drug coated MNPs were characterized by various instrumental methods of analysis and release profile studies were carried out using Franz diffusion cell. Coat-and-poke strategy was employed in administering the drug coated MNPs. Overall, the methods employed in the present study not only help in obtaining MNPs with accurate dimensions but also help in obtaining uniformly drug coated MNPs of gemcitabine for treatment of IBC. Most importantly, 100% drug release was achieved within the first one hour only.

Gemcitabine-Loaded Nanocarrier of Essential Oil from Pulicaria crispa: Preparation, Optimization, and In Vitro Evaluation of Anticancer Activity

The limitations of gemcitabine (GEM) in cancer therapy are due to its poor pharmacokinetics, which cause undesired adverse effects. The current study was aimed at investigating the anticancer effect and apoptotic mechanism of synthesized nanoemulsion (NE) containing Pulicaria crispa essential oil (PC-EO) and GEM (PC-NE:GEM) on MCF-7 and Hep-G2 cancer cell lines. An optimized NE formulation was selected based on the Box–Behnken method. The droplet size of the optimized PC-NE was 9.93 ± 0.53 nm, but after GEM loading, it was increased to 11.36 ± 0.0.21 nm. Results from FTIR revealed that GEM was successfully loaded onto PC-NE. The antineoplastic effect of PC-NE:GEM on MCF-7 and Hep-G2 cancer cells was increased more than 100-fold relative to that of GEM. A combination index and isobologram based on CompuSyn software revealed the synergistic effect of the formulation produced by a 1:1 ratio combination of PC-NE and GEM. These findings were confirmed by examination of cellular morphologies. The combination formulation strongly induced about 4.48-fold and 2.95-fold increases in apoptosis in MCF-7 and Hep-G2 cells, respectively, when compared with GEM. Moreover, PC-NE:GEM produced a synergistic increase in ROS production in MCF-7 cells (15.23%) and Hep-G2 cells (31.69%), when compared with GEM. In addition, PC-NE:GEM enhanced the activation of the intrinsic apoptosis pathway through upregulation of expressions of p53 and Caspase-3, and downregulation of Bcl-2 expression in MCF-7 cells, while the expressions of Caspase-3, Bax, and p53 were upregulated in HepG2 cells. These results indicate that the GEM-loaded NE containing PC-EO may reduce the dose of GEM and eliminate the associated side effects.

Poly(N-vinylcaprolactam) containing solid lipid polymer hybrid nanoparticles for controlled delivery of a hydrophilic drug gemcitabine hydrochloride

Folic acid tagged and hydrophilic polymer containing solid lipid nanoparticles (SLNs) were formulated for the controlled and targeted delivery of gemcitabine, a hydrophilic drug. Drug loaded SLNs were prepared by double emulsion method and optimized by 32 level factorial design. Then, a hydrophilic polymer, namely, poly(N-vinylcaprolactam) (PVCL) was incorporated in the optimized SLN batch in the first aqueous phase (W1) to obtain solid lipid polymer hybrid nanoparticles (SLPHNs) that were further decorated with folic acid (F-SLPHNs). TEM analysis of SLNs and SLPHNs revealed the spherical shape with no aggregation while SLPHNs showed higher % EE. SLPHNs exhibited limited burst release of gemcitabine compared to SLNs as well as lower overall % release. All the formulations showed good cytocompatibility against MDA-MB-231 cell lines and folic acid-tagged hybrid particles (F-SLPHNs) showed remarkably higher cellular uptake.

Redox-responsive self-assembled polymeric nanoprodrug for delivery of gemcitabine in B-cell lymphoma therapy

Gemcitabine, as a standard and classic strategy for B-cell lymphoma in the clinic, is limited by its poor pharmacodynamics. Although stimuli-responsive polymeric nanodelivery systems have been widely investigated in the past decade, issues such as complicated procedures, low loading capacity, and uncontrollable release kinetics still hinder their clinical translation. In view of the above considerations, we attempt to construct hyperbranched polyprodrug micelles with considerable drug loading via simple procedures and make use of the particularity of the tumor microenvironment to ensure that the micelles are "inactivated" in normal tissues and "activated" in the tumor microenvironment. Hence, in this work, a redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) with considerable loading capacity (≈ 24.6%) exhibited on-demand and accurate control of gemcitabine release under a simulated tumor microenvironment and thus significantly induced the apoptosis of B-cell lymphoma in vitro. Moreover, in the A20 tumor xenograft murine model, GSP NPs efficiently decreased the expansion of tumor tissues with minimal systemic toxicity. In summary, these redox-responsive and self-assembling GSP NPs with a facile one-pot synthesis procedure may hold great potency in clinical translation for enhanced chemotherapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: A redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) exhibited significant tumor therapeutic effects in vitro and in vivo. The polyprodrug GEM-S-S-PEG prepared in this study shows the great potential of redox-responsive nanodrugs for antitumor activity, which provides a reference value for the optimization of the design of functional polyprodrugs.

Fabrication of dopamine conjugated with protein @metal organic framework for targeted drug delivery: A biocompatible pH-Responsive nanocarrier for gemcitabine release on MCF‑7 human breast cancer cells

Metal-organic structures (MOF), modern extremely proliferous materials consisting of metal ions and organic coordinating molecules, has become a promising biomedical material because of its unusual features, including great surface area, wide pore volume, flexible functionality and superior performance for drug loading. In the current investigation, Gemcitabine Hydrochloride (Gem), an anticancer drug, and Amygdalin (Amy) were loaded into a nanocomposite structure formed from bovine serum albumin (BSA) as a center and zeolytic imidazolate framework-8 (ZIF-8) as a pH sensitive protective coating. The formed BSA-Gem@ZIF-8 and BSA-Gem-Amy@ZIF-8 were successively coated by polydopamine, chelated by Au³⁺ and conjugated via gallic acid (GA), acquired ZIF-8 structure as a multifunctional nanocarrier at the end. It was confirmed by different characterization methods that the nanocarrier was successfully produced. Due to the nature of ZIF-8, pH dependent releases of BSA-Gem@ZIF-8/Dopa/GA and BSA-Gem-Amy@ZIF-8/Dopa/GA were observed in in vitro studies. Cytotoxicity and apoptotic effects of these nanocarriers were evaluated using WST-1 and acridine orange staining in MCF-7 human breast cancer and HUVEC control cell lines. In-vitro cytotoxicity studies showed that both BSA-Gem@ZIF-8/Dopa/GA and BSA-Gem-Amy@ZIF-8/Dopa/GA were more effective than gemcitabine alone in MCF-7 cells with less toxicity in HUVEC cells. Additionally, both pH-responsive nanocarriers induced more apoptotic cell death in MCF-7 cells. We therefore believe that the built multifunctional nanocarrier based on ZIF-8 could be an alternative therapeutic strategy the use of gemcitabine for cancer therapy.

Opportunities and challenges of fatty acid conjugated therapeutics

Instability, poor cellular uptake and unfavorable pharmacokinetics and biodistribution of many therapeutic molecules require modification in their physicochemical properties. The conjugation of these APIs with fatty acids has demonstrated an enhancement in their lipophilicity and stability. The improvement in the formulations that resulted from the conjugation of a drug with a fatty acid includes increased half-life, enhanced cellular uptake and retention, targeted tumor delivery, reduced chemoresistance in cancer, and improved blood-brain-barrier (BBB) penetration. In this review, various therapeutic molecules, including small molecules, peptides and oligonucleotides, that have been conjugated with fatty acid have been thoroughly discussed along with various conjugation strategies. The application of nano-system based delivery is gaining a lot of attention due to its ability to provide controlled drug release, targeting and reducing the extent of side effects. This review also covers various nano-carriers that have been utilized for the delivery of fatty acid drug conjugates. The enhanced lipophilicity of the drug-fatty acid conjugate has shown to enhance the affinity of the drug towards these carriers, thereby increasing the entrapment efficiency and formulation performance.

Mechanochemical activation of disulfide-based multifunctional polymers for theranostic drug release

Drug delivery systems responsive to physicochemical stimuli allow spatiotemporal control over drug activity to overcome limitations of systemic drug administration. Alongside, the non-invasive real-time tracking of drug release and uptake remains challenging as pharmacophore and reporter function are rarely unified within one molecule. Here, we present an ultrasound-responsive release system based on the mechanochemically induced 5-exo-trig cyclization upon scission of disulfides bearing cargo molecules attached via β-carbonate linker within the center of a water soluble polymer. In this bifunctional theranostic approach, we release one reporter molecule per drug molecule to quantitatively track drug release and distribution within the cell in real-time. We use N-butyl-4-hydroxy-1,8-naphthalimide and umbelliferone as fluorescent reporter molecules to accompany the release of camptothecin and gemcitabine as clinically employed anticancer agents. The generality of this approach paves the way for the theranostic release of a variety of probes and drugs by ultrasound.

A theranostic approach for the mechanochemically induced release of drugs is presented to track drug release and uptake in real-time.

Cationic/Anionic Polyelectrolyte (PLL/PGA) Coated Vesicular Phospholipid Gels (VPGs) Loaded with Cytarabine for Sustained Release and Anti-glioma Effects

Background

Cationic and anionic polymer-modified nanoparticles offer promising properties for the drug and gene delivery. Our study uses cationic/anionic polyelectrolyte coated vesicular phospholipid gels (VPGs) loaded with cytarabine (Ara-C) that enhance in vitro and in vivo anti-glioma effects.

Methods

Sodium cholesteryl sulfate (SCS) or octadecylamine (ODA) incorporated in a phospholipids phase were used to prepare charged VPGs, and cationic ε-polylysine (PLL) coated VPGs (PLL-SCS VPGs) and anionic γ-polyglutamic acid (PGA) coated VPGs (PGA-ODA VPGs) were prepared via electrostatic interactions, respectively. The morphology, particle size, zeta potential, rheology properties, and in vitro release were then characterized. The in vitro cytotoxicity and cellular uptake were evaluated on U87-MG glioma cells. The in vivo antitumor effects were studied on BALB/c nude mice bearing a right flank U87-MG glioma model.

Results

The TEM images and physicochemical properties of cationic/anionic polyelectrolyte coated VPGs exhibited that polymers covered on the vesicular surface. The results of rheologic property analysis showed that cationic/anionic polyelectrolyte coated VPGs enhanced the viscosity of uncoated VPGs. The in vitro release experiments revealed that cationic/anionic polyelectrolyte coated VPGs kept Ara-C sustained release up to 18 days. Specially, compared with PLL-SCS VPGs, PGA-ODA VPGs demonstrated higher in vitro cytotoxicity and cellular uptake efficiency in U87-MG glioma cells, and enhanced in vivo antitumor effects when subcutaneously injected around the tumor. No severe toxicity appeared in the right flank U87-MG glioma model of BALB/c nude mice.

Conclusion

Anionic γ-PGA coated VPGs were superior to cationic PLL coated VPGs in terms of improving the anti-glioma effect for local delivery.

A novel gemcitabine derivative-loaded liposome with great pancreas-targeting ability

Gemcitabine (Gem) is a standard first-line treatment for pancreatic cancer (PC). However, its chemotherapeutic efficacy is hampered by various limitations such as short half-life, metabolic inactivation, and lack of tumor localizing. We previously synthesized a lipophilic Gem derivative (Gem formyl hexadecyl ester, GemC16) that exhibited improved antitumor activity in vitro. In this study, a target ligand N,N-dimethyl-1,3-propanediamine was conjugated to 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[hydroxyl succinimidyl (polyethylene glycol-2000)] (DSPE-PEG-NHS) to form DSPE-PEG-2N. Then, pancreas-targeting liposomes (2N-LPs) were prepared using the film dispersion-ultrasonic method. GemC16-loaded 2N-LPs displayed near-spherical shapes with an average size distribution of 157.2 nm (polydispersity index (PDI) = 0.201). The encapsulation efficiency of GemC16 was up to 97.3% with a loading capacity of 8.9%. In human PC cell line (BxPC-3) and rat pancreatic acinar cell line (AR42J), cellular uptake of 2N-LPs was significantly enhanced compared with that of unmodified PEG-LPs. 2N-LPs exhibited more potent in vitro cytotoxicity against BxPC-3 and AR42J cell lines than PEG-LPs. After systemic administration in mice, 2N-LPs remarkably increased drug distribution in the pancreas. In an orthotopic tumor mouse model of PC, GemC16-bearing liposomes were more effective in preventing tumor growth than free GemC16. Among these treatments, 2N-LPs showed the best curative effect. Together, 2N-LPs represent a promising nanocarrier to achieve pancreas-targeting drug delivery, and this work would provide new ideas for the chemotherapy of PC.

CYR61/CCN1 Regulates dCK and CTGF and Causes Gemcitabine-resistant Phenotype in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) develops extrinsic- and intrinsic-resistant phenotypes to prevent chemotherapies from entering into the cells by promoting desmoplastic reactions (DR) and metabolic malfunctions of the drugs. It is well established that these responses are also associated with pancreatic cancer cells' gemcitabine resistance. However, the mechanism by which these resistant pathways function in the pancreatic cancer cells remains poorly understood. In these studies, we show that CYR61/CCN1 signaling plays a vital role in making pancreatic cancer cells resistant to gemcitabine in vitro and also in a tumor xenograft model. We proved that the catastrophic effect of gemcitabine could significantly be increased in gemcitabine-resistant PDAC cells when CYR61/CCN1 is depleted, while this effect can be suppressed in gemcitabine-sensitive neoplastic cells by treating them with CYR61/CCN1 recombinant protein. Ironically, nontransformed pancreatic cells, which are sensitive to gemcitabine, cannot be resistant to gemcitabine by CYR61/CCN1 protein treatment, showing a unique feature of CYR61/CCN signaling that only influences PDAC cells to become resistant. Furthermore, we demonstrated that CYR61/CCN1 suppresses the expression of the gemcitabine-activating enzyme deoxycytidine kinase (dCK) while it induces the expression of a DR-promoting factor CTGF (connective tissue growth factor) in pancreatic cancer cells in vitro and in vivo Thus, the previously described mechanisms (dCK and CTGF pathways) for gemcitabine resistance may be two novel targets for CYR61/CCN1 to protect pancreatic cancer cells from gemcitabine. Collectively, these studies reveal a novel paradigm in which CYR61/CCN1regulates both extrinsic and intrinsic gemcitabine resistance in PDAC cells by employing unique signaling pathways.

Vesicular phospholipid gels as drug delivery systems for small molecular weight drugs, peptides and proteins: State of the art review

Lipid-based drug delivery has been investigated for a long time when it comes to liposomes and solid-lipid implants or solid-lipid nanoparticles. The promising, characteristic properties of these systems have led to the development of newer lipid-based drug delivery systems for the sustained release of drugs like liposomes for sustained delivery of substances, DepoFoam™ technology, phospholipid-based phase separation gels and vesicular phospholipid gels. Vesicular phospholipid gels (VPGs) are highly concentrated, viscous dispersions of high amounts of phospholipids in aqueous drug solution. The easy, solvent-free manufacturing process, high biocompatibility and various applications, as depot formulation for the sustained delivery of drugs and as a storage form of small unilamellar vesicles make VPGs highly attractive as drug carriers. Over the last years, the solvent free preparation process has advanced from high pressure homogenization to dual centrifugation (DC). Thereby a very simple one step process has been established for the preparation of VPGs. The semisolid VPG was first described in 1997 by Brandl et al. Since then, many formulations have been developed, encapsulating small molecular weight drugs like 5-FU (2003), cetrorelix (2005), cytarabine (2012) and exenatide (2015). In 2010, the first pharmaceutical protein, erythropoietin, was encapsulated in VPGs and sustained release of the substance was shown in vitro. In 2015, G-CSF was encapsulated in VPGs and tested in vivo for rotator cuff repair in a rat model and for PEGylated IFN-β-1b sustained release from vesicular phospholipid gels was demonstrated in vitro. Further, a very elegant administration technique for VPGs via needle-free injection was established. However this promising drug delivery system does still leave space for improvement and optimization. This review summarizes information about lipid-based depot systems in general and focuses on the historical development of VPGs. It emphasizes the advantages and drawbacks of VPGs as drug delivery device. Additionally, novel preparation methods and applications of VPGs will be discussed. A focus will be set on delivery of pharmaceutical proteins and peptides.

Poly (l-glutamic acid)-g-methoxy poly (ethylene glycol)-gemcitabine conjugate improves the anticancer efficacy of gemcitabine

Gemcitabine is widely used for anticancer therapy. However, its short blood circulation time and poor stability greatly impair its application. To solve this problem, we prepared a poly (l-glutamic acid)-g-methoxy poly (ethylene glycol)-gemcitabine conjugate (l-Gem) with a 14.3 wt% drug-loading content. l-Gem showed concentration- and time-dependent cytotoxicity towards 4T1, LLC, MIA PaCa-2 and A2780 in vitro. Pharmacokinetic and biodistribution studies indicated that l-Gem had remarkably enhanced blood stability, prolonged blood circulation time and greatly improved selective tumor distribution compared with free gemcitabine. The area under the concentration-time curve from zero to infinity [AUC_(0-∞)] of l-Gem in plasma was 43-fold higher than that of free gemcitabine. The AUC_(0-∞) of the inactive metabolite, 2'-deoxy-2',2'-difluorouridine in the l-Gem group was ∼20% of that observed in the free gemcitabine group. The drug tumor accumulation ratio in the l-Gem group relative to the free gemcitabine group was 9.9 at 36 h, while the tumor AUC ratio was 15.8. Testing on Balb/C mice bearing the 4T1 tumor further demonstrated that l-Gem had significantly higher anticancer efficacy than free gemcitabine in vivo. These findings indicated that l-Gem has great potential for cancer treatment.

Convection enhanced delivery of liposome encapsulated doxorubicin for brain tumour therapy

Convection enhanced delivery is promising to overcome the blood brain barrier. However, the treatment is less efficient in clinic due to the rapid elimination of small molecular drugs in brain tumours. In this study, numerical simulation is applied to investigate the convection enhanced delivery of liposome encapsulated doxorubicin under various conditions, based on a 3-D brain tumour model that is reconstructed from magnetic resonance images. Treatment efficacy is evaluated in terms of the tumour volume where the free doxorubicin concentration is above LD90. Simulation results denote that intracerebral infusion is effective in increasing the interstitial fluid velocity and inhibiting the fluid leakage from blood around the infusion site. Comparisons with direct doxorubicin infusion demonstrate the advantages of liposomes in enhancing the doxorubicin accumulation and penetration in the brain tumour. Delivery outcomes are determined by both the intratumoural environment and properties of therapeutic agents. The treatment efficacy can be improved by either increasing the liposome solution concentration and infusion rate, administrating liposomes in the tumour with normalised microvasculature density, or using liposomes with low vascular permeability. The delivery is less sensitive to liposome diffusivity in the examined range (E-11~E-7 cm²/s) as convective transport is dominative in determining the liposome migration. Drug release rate is able to be optimised by keeping a trade-off between enhancing the drug penetration and providing sufficient free doxorubicin for effective cell killing. Results from this study can be used to improve the regimen of CED treatments.

Novel Hyaluronic Acid Conjugates for Dual Nuclear Imaging and Therapy in CD44-Expressing Tumors in Mice In Vivo

Hyaluronic acid, a natural CD44 receptor ligand, has attracted attention in the past years as a macromolecular delivery of anticancer agents to cancer. At the same time, the clinical applications of Gemcitabine (Gem) have been hindered by its short biological half-life, high dose and development of drug resistance. This work reports the synthesis of a hyaluronic acid (HA) conjugate for nuclear imaging, and in vivo Gem delivery to CD44-expressing solid tumors in mice. HA was individually conjugated, via amide coupling, to Gem (HA-Gem), 4'-(aminomethyl)fluorescein hydrochloride (HA-4'-AMF) or tris(hydroxypyridinone) amine (HA-THP) for cancer therapy, in vitro tracking or single photon emission computed tomography/computed tomography (SPECT/CT) imaging, respectively. Gem conjugation to HA was directly confirmed by nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) and UV-visible spectrometry, or indirectly by a nucleoside transporter inhibition study. Gem conjugation to HA improved its plasma stability, reduced blood hemolysis and resulted in delayed cytotoxicity in vitro. Uptake inhibition studies in colon CT26 and pancreatic PANC-1 cells, by flow cytometry, revealed that uptake of fluorescent HA conjugate is CD44 receptor and macropinocytosis-dependent. Gamma scintigraphy and SPECT/CT imaging confirmed the relatively prolonged blood circulation profile and uptake in CT26 (1.5 % ID/gm) and PANC-1 (1 % ID/gm) subcutaneous tumors at 24 h after intravenous injection in mice. Four injections of HA-Gem at ~15 mg/kg, over a 28-day period, resulted in significant delay in CT26 tumor growth and prolonged mice survival compared to the free drug. This study reports for the first time dual nuclear imaging and drug delivery (Gem) of HA conjugates to solid tumors in mice. The conjugates show great potential in targeting, imaging and killing of CD44-over expressing cells in vivo. This work is likely to open new avenues for the application of HA-based macromolecules in the field of image-guided delivery in oncology.

Recent advances in drug delivery strategies for improved therapeutic efficacy of gemcitabine

Gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) is an efficacious anticancer agent acting against a wide range of solid tumors, including pancreatic, non-small cell lung, bladder, breast, ovarian, thyroid and multiple myelomas. However, short plasma half-life due to metabolism by cytidine deaminase necessitates administration of high dose, which limits its medical applicability. Further, due to its hydrophilic nature, it cannot traverse cell membranes by passive diffusion and, therefore, enters via nucleoside transporters that may lead to drug resistance. To circumvent these limitations, macromolecular prodrugs and nanocarrier-based formulations of Gemcitabine are gaining wide recognition. The nanoformulations based approaches by virtue of their controlled release and targeted delivery have proved to improve bioavailability, increase therapeutic efficacy and reduce adverse effects of the drug. Furthermore, the combination of Gemcitabine with other anticancer agents as well as siRNAs using nanocarriers has also been investigated in order to enhance its therapeutic potential. This review deals with challenges and recent advances in the delivery of Gemcitabine with particular emphasis on macromolecular prodrugs and nanomedicines.

Thermosensitive gemcitabine-magnetoliposomes for combined hyperthermia and chemotherapy

The combination of magnetic hyperthermia therapy with the controlled release of chemotherapeutic agents in tumors may be an efficient therapeutic with few side effects because the bioavailability, tolerance and amount of the drug can be optimized. Here, we prepared magnetoliposomes consisting of magnetite nanoparticle cores and the anticancer drug gemcitabine encapsulated by a phospholipid bilayer. The potential of these magnetoliposomes for controlled drug release and cancer treatment via hyperthermic behavior was investigated. The magnetic nanoparticle encapsulation efficiency was dependent on the initial amount of magnetite nanoparticles present at the encapsulation stage; the best formulation was 66%. We chose this formulation to characterize the physicochemical properties of the magnetoliposomes and to encapsulate gemcitabine. The mean particle size and distribution were determined by dynamic light scattering (DLS), and the zeta potential was measured. The magnetoliposome formulations all had acceptable characteristics for systemic administration, with a mean size of approximately 150 nm and a polydispersity index <0.2. The magnetoliposomes were stable in aqueous suspension for at least one week, as determined by DLS. Temperature increases due to the dissipation energy of magnetoliposome suspensions subjected to an applied alternating magnetic field (AMF) were measured at different magnetic field intensities, and the values were appropriated for cancer treatments. The drug release profile at 37 °C showed that 17% of the gemcitabine was released after 72 h. Drug release from magnetoliposomes exposed to an AMF for 5 min reached 70%.

EGFR-Targeted Polymeric Mixed Micelles Carrying Gemcitabine for Treating Pancreatic Cancer

The objective of this study was to design GE11 peptide (YHWYGYTPQNVI) linked micelles of poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate-graft-gemcitabine-graft-dodecanol (PEG-b-PCC-g-GEM-g-DC) for enhanced stability and target specificity of gemcitabine (GEM) to EGFR-positive pancreatic cancer cells. GE11-PEG-PCD/mPEG-b-PCC-g-GEM-g-DC mixed micelles showed EGFR-dependent enhanced cellular uptake, and cytotoxicity as compared to scrambled peptide HW12-PEG-PCD/mPEG-b-PCC-g-GEM-g-DC mixed micelles and unmodified mPEG-b-PCC-g-GEM-g-DC micelles. Importantly, GE11-linked mixed micelles preferentially accumulated in orthotopic pancreatic tumor and tumor vasculature at 24 h post systemic administration. GE11-linked mixed micelles inhibited orthotopic pancreatic tumor growth compared to HW12-linked mixed micelles, unmodified mPEG-b-PCC-g-GEM-g-DC micelles, and free GEM formulations. Tumor growth inhibition was mediated by apoptosis of tumor cells and endothelial cells as determined by immunohistochemical staining. In summary, GE11-linked mixed micelles is a promising approach to treat EGFR overexpressing cancers.

Tumor priming by Apo2L/TRAIL reduces interstitial fluid pressure and enhances efficacy of liposomal gemcitabine in a patient derived xenograft tumor model

Interstitial fluid pressure (IFP) is elevated in tumors and high IFP, a negative cancer prognosticator, is known to limit the uptake and efficacy of anti-tumor therapeutics. Approaches that alter the tumor microenvironment and enhance uptake of therapeutics are collectively referred to as tumor "priming". Here we show that the cytotoxic biological therapy Apo2L/TRAIL can prime the tumor microenvironment and significantly lower IFP in three different human tumor xenograft models (Colo205, MiaPaca-2 and a patient gastrointestinal adenocarcinoma tumor xenograft). We found that a single dose of Apo2L/TRAIL resulted in a wave of apoptosis which reached a maximum at 8h post-treatment. Apoptotic debris subsequently disappeared concurrent with an increase in macrophage infiltration. By 24h post-treatment, treated tumors appeared less condensed with widening of the stromal areas which increased at 48 and 72h. Analysis of tumor vasculature demonstrated a significant increase in overall vessel size at 48 and 72h although the number of vessels did not change. Notably, IFP was significantly reduced in these tumors by 48h after Apo2L/TRAIL treatment. Administration of gemcitabine at this time resulted in increased tumor uptake of both gemcitabine and liposomal gemcitabine and significantly improved anti-tumor efficacy of liposomal gemcitabine. These results suggest that Apo2L/TRAIL has a potential as a tumor priming agent and provides a rationale for developing a sequencing schema for combination therapy such that an initial dose of Apo2L/TRAIL would precede administration of gemcitabine or other therapies.

LeciPlex, invasomes, and liposomes: A skin penetration study

The present study compares three vesicular systems, cationic LeciPlex, invasomes, and conventional liposomes for their ability to deliver drugs deep into the skin. Skin penetration ability of the three vesicular systems was studied for two drugs namely idebenone (antioxidant/anticancer) and azelaic acid (antiacne). All systems showed sizes in nanometer range with small polydispersity indices. Vesicular systems were characterized by CryoTEM studies to understand the differences in morphology of the vesicular systems. Ex vivo human skin penetration studies suggested a pattern in penetration of drugs in different layers of the skin: LeciPlex showed higher penetration for idebenone whereas invasomes showed higher penetration of azelaic acid. Ex vivo study using a fluorescent dye (DiI) was performed to understand the differences in the penetration behavior of the three vesicular systems on excised human skin. In vitro cytotoxicity studies on B16F10 melanoma cell lines revealed, when loaded with idebenone, LeciPlex formulations had the superior activity followed by invasomes and liposomes. In vitro antimicrobial study of azelaic acid loaded systems on Propionibacterium acne revealed high antimicrobial activity for DDAB leciplex followed by almost equal activity for invasomes and CTAB LeciPlex followed by liposomes. Whereas antiacne efficacy study in rats for azelaic acid loaded systems, invasomes exhibited the best antiacne efficacy followed by liposomes and LeciPlex.

Sustained delivery of cytarabine-loaded vesicular phospholipid gels for treatment of xenografted glioma

This study described the development of vesicular phospholipid gels (VPGs) for sustained delivery of cytarabine (Ara-C) for the treatment of xenografted glioma. Ara-C-loaded VPGs in the state of a semisolid phospholipid dispersion looked like numerous vesicles tightly packing together under the freeze-fracture electron microscopy (FF-TEM), their release profiles displayed sustained drug release up to 384 h in vitro. The biodistribution of Ara-C in the rat brain showed that Ara-C-loaded VPGs could maintain therapeutic concentrations up to 5mm distance from the implantation site in brain tissue within 28 days. At the same time, fluorescence micrograph confirmed drug distribution in brain tissue visually. Furthermore, after single administration, Ara-C-loaded VPGs group significantly inhibited the U87-MG glioma growth in right flank in comparison with Ara-C solution (p<0.01). It was explained that the entrapped drug in VPGs could avoid degradation from cytidine deaminase and sustained release of drug from Ara-C-loaded VPGs could maintain the effective therapeutic levels for a long time around the tumor. In conclusion, Ara-C-loaded VPGs, with the properties of sustained release, high penetration capacity, nontoxicity and no shape restriction of the surgical cavity, are promising local delivery systems for post-surgical sustained chemotherapy against glioma.

Multifunctional polymersomes for cytosolic delivery of gemcitabine and doxorubicin to cancer cells

Although liposomes are widely used as carriers of drugs and imaging agents, they suffer from a lack of stability and the slow release of the encapsulated contents at the targeted site. Polymersomes (vesicles of amphiphilic polymers) are considerably more stable compared to liposomes; however, they also demonstrate a slow release for the encapsulated contents, limiting their efficacy as a drug-delivery tool. As a solution, we prepared and characterized echogenic polymersomes, which are programmed to release the encapsulated drugs rapidly when incubated with cytosolic concentrations of glutathione. These vesicles encapsulated air bubbles inside and efficiently reflected diagnostic-frequency ultrasound. Folate-targeted polymersomes showed an enhanced uptake by breast and pancreatic-cancer cells in a monolayer as well as in three-dimensional spheroid cultures. Polymersomes encapsulated with the anticancer drugs gemcitabine and doxorubicin showed significant cytotoxicity to these cells. With further improvements, these vesicles hold the promise to serve as multifunctional nanocarriers, offering a triggered release as well as diagnostic ultrasound imaging.

Lecithin-based nanostructured gels for skin delivery: an update on state of art and recent applications

Conventional carriers for skin delivery encounter obstacles of drug leakage, scanty permeation and low entrapment efficiency. Phospholipid nanogels have recently been recognized as prominent delivery systems to circumvent such obstacles and impart easier application. The current review provides an overview on different types of lecithin nanostructured gels, with particular emphasis on liposomal versus microemulsion gelled systems. Liposomal gels investigated encompassed classic liposomal hydrogel, modified liposomal gels (e.g. Transferosomal, Ethosomal, Pro-liposomal and Phytosomal gels), Microgel in liposomes (M-i-L) and Vesicular phospholipid gel (VPG). Microemulsion gelled systems encompassed Lecithin microemulsion-based organogels (LMBGs), Pluronic lecithin organogels (PLOs) and Lecithin-stabilized microemulsion-based hydrogels. All systems were reviewed regarding matrix composition, state of art, characterization and updated applications. Different classes of lecithin nanogels exhibited crucial impact on transdermal delivery regarding drug permeation, drug loading and stability aspects. Future perspectives of this theme issue are discussed based on current laboratory studies.

Self-assembling, amphiphilic polymer-gemcitabine conjugate shows enhanced antitumor efficacy against human pancreatic adenocarcinoma

The therapeutic efficacy of gemcitabine is severely compromised due to its rapid plasma metabolism. Moreover, its hydrophilicity poses a challenge for its efficient entrapment in nanosized delivery systems and to provide a sustained release profile. In this study, gemcitabine was covalently conjugated to poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate) (PEG-PCC) which could self-assemble into micelles of 23.6 nm. These micelles afforded protection to gemcitabine from plasma metabolism as evident by negligible amount of gemcitabine and its metabolite dFdU detected in the plasma after 24 h. A controlled release of gemcitabine from the micelles was observed with 53.89% drug release in 10 days in the presence of protease enzyme Cathepsin B. Gemcitabine conjugated micelles were cytotoxic, showed internalization, and induced cell apoptosis in MIA PaCa-2 and L3.6pl pancreatic cancer cell lines. These micelles efficiently inhibited tumor growth when injected intravenously into MIA PaCa-2 cell derived xenograft tumor bearing NSG mice at a dose of 40 mg/kg in terms of reduced tumor volume and tumor weight (0.38 g vs 0.58 g). TUNEL assay revealed that gemcitabine conjugated micelles induced a much higher extent of apoptosis in the tumor tissues compared to free gemcitabine. In conclusion, gemcitabine conjugated micelles were able to enhance the drug payload, protect it from rapid plasma metabolism, and provide a sustained release and showed enhanced antitumor activity, and thus have the potential to provide a better therapeutic alternative for treating pancreatic cancer.

Targeting gemcitabine containing liposomes to CD44 expressing pancreatic adenocarcinoma cells causes an increase in the antitumoral activity

Pancreatic adenocarcinoma is often diagnosed when metastatic events have occurred. The early spread of circulating cancer cells expressing the CD44 receptor may play a crucial role in this process. In this study, we have investigated the cellular delivery ability and both in vitro and in vivo anti-tumoral activity of liposomes conjugated with two different low molecular weight hyaluronic acids (HA 4.8kDa and HA 12kDa), the primary ligand of CD44, and containing a lipophilic gemcitabine (GEM) pro-drug. By confocal microscopy and flow cytometry analyses, we demonstrate that the cellular uptake into a highly CD44-expressing pancreatic adenocarcinoma cell line is higher with HA-conjugated (12kDa>4.8kDa) than non-conjugated liposomes. Consistently, in vitro cytotoxic assays display an increased sensitivity towards GEM containing HA-liposomes, compared to non-conjugated liposomes. Conversely, CD44 non-expressing normal cells show a similar uptake and in vitro cytotoxicity with both HA-conjugated and non-conjugated liposomes. Furthermore, we demonstrate that the HA-liposomes are taken up into the cells via lipid raft-mediated endocytosis. All the liposome formulations containing GEM show a higher antitumoral activity than free GEM in a mouse xenograft tumor model of human pancreatic adenocarcinoma. The 12kDa HA-liposomes have the strongest efficiency, while non-conjugated liposomes and the 4.8kDa HA-liposomes are similarly active. Taken together, our results provide a strong rationale for further development of HA-conjugated liposomes to treat pancreatic adenocarcinoma.

Gemcitabine-loaded liposomes: rationale, potentialities and future perspectives

This review describes the strategies used in recent years to improve the biopharmaceutical properties of gemcitabine, a nucleoside analog deoxycytidine antimetabolite characterized by activity against many kinds of tumors, by means of liposomal devices. The main limitation of using this active compound is the rapid inactivation of deoxycytidine deaminase following administration in vivo. Consequently, different strategies based on its encapsulation/complexation in innovative vesicular colloidal carriers have been investigated, with interesting results in terms of increased pharmacological activity, plasma half-life, and tumor localization, in addition to decreased side effects. This review focuses on the specific approaches used, based on the encapsulation of gemcitabine in liposomes, with particular attention to the results obtained during the last 5 years. These approaches represent a valid starting point in the attempt to obtain a novel, commercializable drug formulation as already achieved for liposomal doxorubicin (Doxil^®, Caelyx^®).

Folate-targeted supramolecular vesicular aggregates as a new frontier for effective anticancer treatment in in vivo model

Supramolecular vesicular aggregates (SVAs), made up by self-assembling liposomes and polyasparthydrazide co-polymers conjugated to folic acid molecules were extensively investigated in this manuscript as potential active targeting formulation for anticancer drug delivery. Folate-targeted systems (FT-SVAs) were used to treat breast cancer and to further proof the potential in vivo administration of these systems for the therapeutic treatment for several aggressive solid tumors. The physicochemical and technological parameters of FT-SVAs are suitable for their potential in vivo administration. The chemotherapeutic activity of GEM-loaded FT-SVAs was increased during in vivo experiments. NOD-SCID mice bearing MCF-7 human xenograft is used as breast cancer model. The measurement of the volume and weight of tumor masses decreased when animal models are treated by using GEM-loaded FT-SVAs, compared to data obtained by using GEM-loaded mPEG-SUVs and the free form of GEM. An almost complete regression of the tumor (≈ 0.2 cm(3)) was observed in NOD-SCID mice bearing MCF-7 human xenografts treated by GEM-loaded FT-SVAs due to the noticeable improvement of GEM pharmacokinetic parameters provided by FT-SVAs with respect to native anticancer drug. The obtained data showed that supramolecular systems could represent an innovative drug delivery system by self-assembling liposomes and biocompatible polymers to be potentially used for anticancer treatment.

Combinatorial therapies improve the therapeutic efficacy of nanoliposomal ceramide for pancreatic cancer

Poor prognosis cancers, such as pancreatic cancer, represent inherent challenges for ceramide-based nanotherapeutics due to metabolic pathways, which neutralize ceramide to less toxic or pro-oncogenic metabolites. We have recently developed a novel 80 nanometer diameter liposomal formulation that incorporates 30 molar percent C6-ceramide, a bioactive lipid that is pro-apoptotic to many cancer cells, but not to normal cells. In this manuscript, we evaluated the efficacy of combining nanoliposomal C6-ceramide (Lip-C6) with either gemcitabine or an inhibitor of glucosylceramide synthase. We first assessed the biological effect of Lip-C6 in PANC-1 cells, a gemcitabine-resistant human pancreatic cancer cell line, and found that low doses alone did not induce cell toxicity. However, cytotoxicity was achieved by combining Lip-C6 with either non-toxic sub-therapeutic concentrations of gemcitabine or with the glucosylceramide synthase inhibitor D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP). Furthermore, these combinations with Lip-C6 cooperatively inhibited PANC-1 tumor growth in vivo. Mechanistically, Lip-C6 inhibited pro-survival Akt and Erk signaling, whereas the nucleoside analog gemcitabine did not. Furthermore, by including PDMP within the nanoliposomes, which halted ceramide neutralization as evidenced by LC-MS3, the cytotoxic effects of Lip-C6 were enhanced. Collectively, we have demonstrated that nanoliposomal ceramide can be an effective anti-pancreatic cancer therapeutic in combination with gemcitabine or an inhibitor of ceramide neutralization.

Squalene based nanocomposites: a new platform for the design of multifunctional pharmaceutical theragnostics

This study reports the design of a novel theragnostic nanomedicine which combines (i) the ability to target a prodrug of gemcitabine to an experimental solid tumor under the influence of a magnetic field with (ii) the imaging of the targeted tumoral nodule. This concept is based on the inclusion of magnetite nanocrystals into nanoparticles (NPs) constructed by self-assembling molecules of the squalenoyl gemcitabine (SQgem) bioconjugate. The nanocomposites are characterized by an unusually high drug loading, a significant magnetic susceptibility, and a low burst release. When injected to the L1210 subcutaneous mice tumor model, these magnetite/SQgem NPs were magnetically guided, and they displayed considerably greater anticancer activity than the other anticancer treatments (magnetite/SQgem NPs nonmagnetically guided, SQgem NPs, or gemcitabine free in solution). The histology and immunohistochemistry investigation of the tumor biopsies clearly evidenced the therapeutic superiority of the magnetically guided nanocomposites, while Prussian blue staining confirmed their accumulation at the tumor periphery. The superior therapeutic activity and enhanced tumor accumulation has been successfully visualized using T(2)-weighted imaging in magnetic resonance imaging (MRI). This concept was further enlarged by (i) the design of squalene-based NPs containing the T(1) Gd(3+) contrast agent instead of magnetite and (ii) the application to other anticancer squalenoyls, such as, cisplatin, doxorubicin, and paclitaxel. Thus, by combining different anticancer medicines as well as contrast imaging agents in NPs, we open the door toward generic conceptual framework for cancer treatment and diagnosis. This new theragnostic nanotechnology platform is expected to have important applications in cancer therapy.

Applications of nanotechnology to imaging and therapy of brain tumors

In the past decade, numerous advances in the understanding of brain tumor physiology, tumor imaging, and tumor therapy have been attained. In some cases, these advances have resulted from refinements of pre-existing technologies (eg, improvements of contrast-enhanced magnetic resonance imaging). In other instances, advances have resulted from development of novel technologies. The development of nanomedicine (ie, applications of nanotechnology to the field of medicine) is an example of the latter. In this review, the authors explain the principles that underlay nanoparticle design and function as well as the means by which nanoparticles can be used for imaging and therapy of brain tumors.

Liposomal squalenoyl-gemcitabine: formulation, characterization and anticancer activity evaluation

A new prodrug of gemcitabine, based on the covalent coupling of squalene to gemcitabine (GemSQ), has been designed to enhance the anticancer activity of gemcitabine, a nucleoside analogue active against a wide variety of tumors. In the present study, the feasibility of encapsulating GemSQ into liposomes either PEGylated or non-PEGylated has been investigated. The in vivo anticancer activity of these formulations has been tested on subcutaneous grafted L1210wt leukemia model and compared to that of free gemcitabine. The liposomal GemSQ appears to be a potential delivery system for the effective treatment of tumors.

Chitosan and glyceryl monooleate nanostructures containing gemcitabine: potential delivery system for pancreatic cancer treatment

The objectives of this study are to enhance cellular accumulation of gemcitabine with chitosan/glyceryl monooleate (GMO) nanostructures, and to provide significant increase in cell death of human pancreatic cancer cells in vitro. The delivery system was prepared by a multiple emulsion solvent evaporation method. The nanostructure topography, size, and surface charge were determined by atomic force microscopy (AFM), and a zetameter. The cellular accumulation, cellular internalization and cytotoxicity of the nanostructures were evaluated by HPLC, confocal microscopy, or MTT assay in Mia PaCa-2 and BxPC-3 cells. The average particle diameter for 2% and 4% (w/w) drug loaded delivery system were 382.3 +/- 28.6 nm, and 385.2 +/- 16.1 nm, respectively with a surface charge of +21.94 +/- 4.37 and +21.23 +/- 1.46 mV. The MTT cytotoxicity dose-response studies revealed the placebo at/or below 1 mg/ml has no effect on MIA PaCa-2 or BxPC-3 cells. The delivery system demonstrated a significant decrease in the IC50 (3 to 4 log unit shift) in cell survival for gemcitabine nanostructures at 72 and 96 h post-treatment when compared with a solution of gemcitabine alone. The nanostructure reported here can be resuspended in an aqueous medium that demonstrate increased effective treatment compared with gemcitabine treatment alone in an in vitro model of human pancreatic cancer. The drug delivery system demonstrates capability to entrap both hydrophilic and hydrophobic compounds to potentially provide an effective treatment option in human pancreatic cancer.