The effect of the acid-sensitivity of 4-(N)-stearoyl gemcitabine-loaded micelles on drug resistance caused by RRM1 overexpression

Effect of the amount of cationic lipid used to complex siRNA on the cytotoxicity and proinflammatory activity of siRNA-solid lipid nanoparticles

When preparing siRNA-encapsulated solid lipid nanoparticles (siRNA-SLNs), cationic lipids are commonly included to condense and lipophilize the siRNA and thus increase its encapsulation in the SLNs. Unfortunately, cationic lipids also contribute significantly to the cytotoxicity and proinflammatory activity of the SLNs. Previously, our group developed a TNF-α siRNA-SLN formulation that showed strong activity against rheumatoid arthritis unresponsive to methotrexate in a mouse model. The siRNA-SLNs were composed of lecithin, cholesterol, an acid-sensitive stearoyl polyethylene glycol (2000) conjugate, and siRNA complexes with 1,2-dioleoyl-3trimethylammonium-propane (DOTAP), a cationic lipid. The present study was designed to study the effect of the amount of DOTAP used to complex the siRNA on the cytotoxicity and proinflammatory activity of the resultant siRNA-SLNs. A small library of siRNA-SLNs prepared at various ratios of DOTAP to siRNA (i.e., nitrogen to phosphate (N/P) ratios ranging from 34:1 to 1:1) were prepared and characterized, and the cytotoxicity and proinflammatory activity of selected formulations were evaluated in cell culture. As expected, the siRNA-SLNs prepared at the highest N/P ratio showed the highest cytotoxicity to J774A.1 macrophage cells and reducing the N/P ratio lowered the cytotoxicity of the siRNA-SLNs. Unexpectedly, the cytotoxicity of the siRNA-SLNs reached the lowest at the N/P ratios of 16:1 and 12:1, and further reducing the N/P ratio resulted in siRNA-SLNs with increased cytotoxicity. For example, siRNA-SLNs prepared at the N/P ratio of 1:1 was more cytotoxic than the ones prepared at the N/P ratio 12:1. This finding was confirmed using neutrophils differentiated from mouse MPRO cell line. The DOTAP release from the siRNA-SLNs prepared at the N/P ratio of 1:1 was faster than from the ones prepared at the N/P ratio of 12:1. The siRNA-SLNs prepared at N/P ratios of 12:1 and 1:1 showed comparable proinflammatory activities in both macrophages and neutrophils. Additionally, the TNF-α siRNA-SLNs prepared at the N/P ratios of 12:1 and 1:1 were equally effective in downregulating TNF-α expression in J774A.1 macrophages. In conclusion, it was demonstrated that at least in vitro in cell culture, reducing the amount of cationic lipids used when preparing siRNA-SLNs can generally help reduce the cytotoxicity of the resultant SLNs, but siRNA-SLNs prepared with the lowest N/P ratio are not necessarily the least cytotoxic and proinflammatory.

Effect of nanoparticle size on their distribution and retention in chronic inflammation sites

Nanomedicines are increasingly researched and used for the treatment of chronic inflammatory diseases. Herein, the effect of the size of nanoparticles on their distribution and retention in chronic inflammatory sites, as compared to healthy tissues, was studied in a mouse model with chronic inflammation in one of the hind footpads. Using PEGylated gold nanoparticles of 2, 10, 100, and 200 nm, we found that although the smaller nanoparticles of 2 and 10 nm showed greater distribution and slower clearance in the inflamed footpad than the relatively larger nanoparticles of 100 and 200 nm, the larger nanoparticles of 100 and 200 nm were more selectively distributed in the inflamed hind footpad than in the healthy hind footpad in the same mouse. Based on these findings, we prepared protein nanoparticles of 100-200 nm with albumin, IgG antibody, or anti-TNF-α monoclonal antibody (mAb). The nanoparticles can release proteins in response to high redox activity and/or low pH, conditions seen in chronic inflammation sites. We then showed that upon intravenous injection, those stimuli-responsive protein nanoparticles distributed more selectively in the inflamed footpad than free proteins and remained longer in the inflamed footpad than similar protein nanoparticles that are not sensitive to high redox activity or low pH. These findings support the feasibility of increasing the selectivity of nanomedicines and protein therapeutics to chronic inflammation sites and prolonging their retention at the sites by innovative nanoparticle engineering.

Strategies to improve the physicochemical properties of peptide-based drugs

Peptides are a rapid-growing class of therapeutics with unique and desirable physicochemical properties. Due to disadvantages such as low membrane permeability and susceptibility to proteolytic degradation, peptide-based drugs have limited bioavailability, a short half-life, and rapid in vivo elimination. Various strategies can be applied to improve the physicochemical properties of peptide-based drugs to overcome limitations such as limited tissue residence time, metabolic instability, and low permeability. Applied strategies including backbone modifications, side chain modifications, conjugation with polymers, modification of peptide termini, fusion to albumin, conjugation with the Fc portion of antibodies, cyclization, stapled peptides, pseudopeptides, cell-penetrating peptide conjugates, conjugation with lipids, and encapsulation in nanocarriers are discussed.

Antitumor Effects of a Solid Lipid Nanoparticle Loaded with Gemcitabine and Oxaliplatin on the Viability, Apoptosis, Autophagy and Hsp90 of Ovarian Cancer Cells

Aim: The present study aimed to explore the sensitizing capability of the anticancer agents, gemcitabine (GEM) and oxaliplatin (OXA), encapsulated in a novel SLN (GEM:OXA-SLN) against the ovarian cancer cell lines.

METHODS

A novel SLN, prepared using hot homogenization by mixing phosphatidylcholine, cholesterol, tween 80 and oleic acid, was characterized using Transmission Electron Microscope and zetasizer. The anticancer activities and the underlying molecular mechanisms of GEM:OXA-SLN were investigated.

RESULTS

The average z-diameter of the homogeneous spherical GEM:OXA-SLN was (70.33 ± 0.70) nm with zeta potential (-7.69 ± 0.61) mV. GEM:OXA-SLN significantly inhibited the viability of ovarian cancer cells in a dose-dependent manner within 24 h. It also triggered the induction of autophagy cellular death, suppression of multidrug resistance efflux pump and inhibition of heat shock protein (Hsp90).

CONCLUSION

The encapsulation of GEM and OXA in SLN improved the efficacy of the drugs and diminished the ovarian cancer cell's resistance.

Nanoparticle-based therapeutic strategies targeting major clinical challenges in pancreatic cancer treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers due to its aggressiveness and the challenges for early diagnosis and treatment. Recently, nanotechnology has demonstrated relevant strategies to overcome some of the major clinical issues in the treatment of PDAC. This review is focused on the pathological hallmarks of PDAC and the impact of nanotechnology to find solutions. It describes the use of nanoparticle-based systems designed for the delivery of chemotherapeutic agents and combinatorial alternatives that address the chemoresistance associated with PDAC, the development of combination therapies targeting the molecular heterogeneity in PDAC, the investigation of novel therapies dealing with the improvement of immunotherapy and handling the desmoplastic stroma in PDAC by remodeling the tumor microenvironment. A special section is dedicated to the design of nanoparticles for unique non-traditional modalities that could be promising in the future for the improvement in the dismal prognosis of PDAC.

Lipid-Based Drug Delivery Systems in Regenerative Medicine

The most important goal of regenerative medicine is to repair, restore, and regenerate tissues and organs that have been damaged as a result of an injury, congenital defect or disease, as well as reversing the aging process of the body by utilizing its natural healing potential. Regenerative medicine utilizes products of cell therapy, as well as biomedical or tissue engineering, and is a huge field for development. In regenerative medicine, stem cells and growth factor are mainly used; thus, innovative drug delivery technologies are being studied for improved delivery. Drug delivery systems offer the protection of therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. Similarly, the delivery systems in combination with stem cells offer improvement of cell survival, differentiation, and engraftment. The present review summarizes the significance of biomaterials in tissue engineering and the importance of colloidal drug delivery systems in providing cells with a local environment that enables them to proliferate and differentiate efficiently, resulting in successful tissue regeneration.

Effect of surface mannosylation on the cytotoxicity and cellular uptake of stearoyl gemcitabine-incorporated, acid-sensitive micelles

Elevated expression of C-type like receptors (CLRs) by tumor cells and tumor-associated macrophages (TAMs) present a unique target for the delivery of anticancer agents. Stearoyl gemcitabine (GemC18)-incorporated, acid-sensitive micelles (G-AS-M) prepared with a stearoyl polyethylene glycol (PEG2000) hydrazone were surface-mannosylated in this study for potential targeted killing of tumor cells and TAMs. The surface mannosylated micelles (i.e. G-MAS-M) were significantly more cytotoxic than the G-AS-M micelles to macrophages and tumor cells that express CLRs. Surprisingly, the uptake of GemC18 in the mannosylated G-MAS-M micelles by the macrophages and tumor cells was lower than that of GemC18 in the G-AS-M micelles. The lack of correlation between the cytoxicity and cellular uptake of GemC18 in the micelles was likely caused by a reduction in the sensitivity of the hydrazone bond linking the PEG2000 to the mannosylated G-MAS-M micelles to hydrolysis, resulting in more stable micelles.

Emerging pro-drug and nano-drug strategies for gemcitabine-based cancer therapy

Gemcitabine has been extensively applied in treating various solid tumors. Nonetheless, the clinical performance of gemcitabine is severely restricted by its unsatisfactory pharmacokinetic parameters and easy deactivation mainly because of its rapid deamination, deficiencies in deoxycytidine kinase (DCK), and alterations in nucleoside transporter. On this account, repeated injections with a high concentration of gemcitabine are adopted, leading to severe systemic toxicity to healthy cells. Accordingly, it is highly crucial to fabricate efficient gemcitabine delivery systems to obtain improved therapeutic efficacy of gemcitabine. A large number of gemcitabine pro-drugs were synthesized by chemical modification of gemcitabine to improve its biostability and bioavailability. Besides, gemcitabine-loaded nano-drugs were prepared to improve the delivery efficiency. In this review article, we introduced different strategies for improving the therapeutic performance of gemcitabine by the fabrication of pro-drugs and nano-drugs. We hope this review will provide new insight into the rational design of gemcitabine-based delivery strategies for enhanced cancer therapy.

Light-Responsive Micelles Loaded With Doxorubicin for Osteosarcoma Suppression

The enhancement of tumor targeting and cellular uptake of drugs are significant factors in maximizing anticancer therapy and minimizing the side effects of chemotherapeutic drugs. A key challenge remains to explore stimulus-responsive polymeric nanoparticles to achieve efficient drug delivery. In this study, doxorubicin conjugated polymer (Poly-Dox) with light-responsiveness was synthesized, which can self-assemble to form polymeric micelles (Poly-Dox-M) in water. As an inert structure, the polyethylene glycol (PEG) can shield the adsorption of protein and avoid becoming a protein crown in the blood circulation, improving the tumor targeting of drugs and reducing the cardiotoxicity of doxorubicin (Dox). Besides, after ultraviolet irradiation, the amide bond connecting Dox with PEG can be broken, which induced the responsive detachment of PEG and enhanced cellular uptake of Dox. Notably, the results of immunohistochemistry in vivo showed that Poly-Dox-M had no significant damage to normal organs. Meanwhile, they showed efficient tumor-suppressive effects. This nano-delivery system with the light-responsive feature might hold great promises for the targeted therapy for osteosarcoma.

Controlled drug release from polyelectrolyte-drug conjugate nanoparticles

Encapsulating drugs in functional nanoparticles provides controlled and targeted release of drugs. In this study, a general approach for encapsulating hydrophobic drugs in polyelectrolyte nanoparticles was developed for a controlled drug release. Gemcitabine (GEM), an anticancer drug for pancreatic ductal adenocarcinoma (PDAC), was used as a model drug to produce poly(acrylic acid) (PAA)-GEM conjugate nanoparticles to achieve a controlled release of GEM in cells. The PAA-GEM conjugate nanoparticles were fabricated by coupling GEM onto PAA through the formation of amide bonds. The hydrophobic interactions of GEM molecules induced the formation of the nanoparticles with the GEM core and PAA shell. Fabrication conditions such as the PAA/GEM ratio and pH were optimized to achieve high structure stability and drug loading efficiency. The size and surface charge of the nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential measurement. The optimized PAA-GEM nanoparticles had a size around 12 nm, 30 nm and 60 nm in dry state, water, and phosphate buffered saline (PBS), respectively. The encapsulation efficiency was 29.29 ± 1.7%, and the loading capacity was 9.44 ± 0.46%. Less than 7% GEM was released from the PAA-GEM nanoparticles after 96 hour incubation in phosphate buffered saline. The cytotoxic efficacy of the PAA-GEM nanoparticles in cancer cells was investigated through viability studies of PANC-1, a human pancreatic cancer cell line. It was found that the PAA-GEM nanoparticles had more than a 48 hour delay of releasing GEM and had the same cytotoxic efficacy in PANC-1 cells as free GEM. The uptake of the PAA-GEM nanoparticles by PANC-1 cells was investigated using PAA-GEM labeled by rhodamine G6. Fluorescence and bright field overlay images indicated that the PAA-GEM nanoparticles were taken up by PANC-1 cells within 2 hours. It is believed that the PAA-GEM nanoparticles were decomposed in PANC-1 cells and GEM was released from the nanoparticles.

Gemcitabine Lipid Prodrugs: The Key Role of the Lipid Moiety on the Self-Assembly into Nanoparticles

A small library of amphiphilic prodrugs has been synthesized by conjugation of gemcitabine (Gem) (a hydrophilic nucleoside analogue) to a series of lipid moieties and investigated for their capacity to spontaneously self-assemble into nanosized objects by simple nanoprecipitation. Four of these conjugates formed stable nanoparticles (NPs), while with the others, immediate aggregation occurred, whatever the tested experimental conditions. Whether such capacity could have been predicted based on the prodrug physicochemical features was a matter of question. Among various parameters, the hydrophilic-lipophilic balance (HLB) value seemed to hold a predictive character. Indeed, we identified a threshold value which well correlated with the tendency (or not) of the synthesized prodrugs to form stable nanoparticles. Such a hypothesis was further confirmed by broadening the analysis to Gem and other nucleoside prodrugs already described in the literature. We also observed that, in the case of Gem prodrugs, the lipid moiety affected not only the colloidal properties but also the in vitro anticancer efficacy of the resulting nanoparticles. Overall, this study provides a useful demonstration of the predictive potential of the HLB value for lipid prodrug NP formulation and highlights the need of their opportune in vitro screening, as optimal drug loading does not always translate in an efficient biological activity.

PD-1 siRNA-Encapsulated Solid Lipid Nanoparticles Downregulate PD-1 Expression by Macrophages and Inhibit Tumor Growth : PD-1 siRNA-Encapsulated Solid Lipid Nanoparticles

The present study was designed to test the hypothesis that programmed cell death-1 (PD-1) siRNA can downregulate PD-1 expression in macrophages in culture and in tumor tissues in mice and inhibit tumor growth in a mouse model. PD-1 siRNA was encapsulated in solid lipid nanoparticles (SLNs), and the physical properties of the resultant SLNs were characterized. The ability of the PD-1 siRNA-SLNs to downregulate PD-1 expression was confirmed in J774A.1 macrophages in culture and in tumor tissues in mice. Moreover, the antitumor activity of the PD-1 siRNA-SLNs was evaluated in a mouse model. The PD-1 siRNA-SLNs were roughly spherical, and their particle size, polydispersity index, and zeta potential were 141 ± 5 nm, 0.17 ± 0.02, and 20.7 ± 4.7 mV, respectively, with an siRNA entrapment efficiency of 98.9%. The burst release of the PD-1 siRNA from the SLNs was minimal. The PD-1 siRNA-SLNs downregulated PD-1 expression on J774A.1 macrophage cell surface as well as in macrophages in B16-F10 tumors pre-established in mice. In mice with pre-established B16-F10 tumors, the PD-1 siRNA-SLNs significantly inhibited the tumor growth, as compared with siRNA-SLNs prepared with non-functional, negative control siRNA. In conclusion, the PD-1 siRNA-SLNs inhibited tumor growth, likely related to their ability to downregulate PD-1 expression by tumor-associated macrophage (TAMs).

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.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Co-delivery of gemcitabine prodrug along with anti NF-κB siRNA by tri-layer micelles can increase cytotoxicity, uptake and accumulation of the system in the cancers

Combination treatment based on gene and chemotherapy is a promising strategy for effective cancer treatment due to the limited therapeutic efficacy of anticancer drugs. Dual functional polymeric micelles (PMs) have been emerged as potent nanocarriers for combinational cancer therapy. In the present study, the potential of tri-layer PMs loaded with anti-nuclear factor-κB (NF-κB) siRNA and 4-(N)-stearoyl gemcitabine (GemC18) has been investigated for cancer treatment. PMs with different core hydrophobicity were prepared by using poly(ε-caprolactone), polyethyleneimine and polyethylene glycol (PCL-PEI-PEG) copolymers and evaluated. The results revealed that GemC18-loaded PMs were significantly more cytotoxic than free drug on breast and pancreatic cancer cells. However, the cytotoxicity of drug loaded micelles was decreased by increasing the micellar core hydrophobicity because of decreasing drug release rate. Moreover, siRNA loaded PMs could considerably inhibit NF-κB expression. PMs loaded with both GemC18 and siRNA exhibited higher capability to induce apoptosis and inhibit migration of both cells. PMs with the most hydrophobic core indicated higher tumor accumulation efficiency via in-vivo imaging study. In conclusion, the prepared PMs hold a promise as an attractive dual functional delivery system for an effective cancer therapy.

Applications of RNA interference in the treatment of arthritis

RNA interference (RNAi) is a cellular mechanism for post-transcriptional gene regulation mediated by small interfering RNA (siRNA) and microRNA. siRNA-based therapy holds significant promise for the treatment of a wide-range of arthritic diseases. siRNA selectively suppresses the expression of a gene product and can thus achieve the specificity that is lacking in small molecule inhibitors. The potential use of siRNA-based therapy in arthritis, however, has not progressed to clinical trials despite ample evidence for efficacy in preclinical studies. One of the main challenges to clinical translation is the lack of a suitable delivery vehicle to efficiently and safely access diverse pathologies. Moreover, the ideal targets in treatment of arthritides remain elusive given the complexity and heterogeneity of these disease pathogeneses. Herein, we review recent preclinical studies that use RNAi-based drug delivery systems to mitigate inflammation in models of rheumatoid arthritis and osteoarthritis. We discuss a self-assembling peptide-based nanostructure that demonstrates the potential of overcoming many of the critical barriers preventing the translation of this technology to the clinic.

Reviewing two decades of nanomedicine implementations in targeted treatment and diagnosis of pancreatic cancer: An emphasis on state of art

Pancreatic cancer is nowadays the most life-threatening cancer type worldwide. The problem of poor diagnosis, anti-neoplastics resistance and biopharmaceutical drawbacks of effective anti-cancer drugs lead to worsen disease state. Nanotechnology-based carrier systems used in both imaging and treatment procedures had solved many of these problems. It is critical to develop advanced detection method to save patients from being too late diagnosed. Targeting the pancreatic cancer cells as well helped in decreasing the side effects associated with normal cells destruction. Drug resistance is another challenge in pancreatic cancer management that can be solved by thorough understanding of the microenvironment associated with the disease to design creative nanocarriers. This is the first article to review multifaceted approaches of nanomedicine in pancreatic cancer detection and management. Additionally, mortality rates in selected Arab and European countries were illustrated herein. An emphasis was given on therapeutic and diagnostic challenges and different nanotechnologies adopted to overcome. The four main approaches encompassed nanomedicine for herbal treatment, nanomedicine of synthetic anti-cancer drugs, metal nanoparticles as a distinct treatment policy and nanotechnology for cancer diagnosis. Future research perspectives have been finally proposed.

Ectopic high endothelial venules in pancreatic ductal adenocarcinoma: A unique site for targeted delivery

BACKGROUND

Nanomedicine offers an excellent opportunity to tackle treatment-refractory malignancies by enhancing the delivery of therapeutics to the tumor site. High endothelial venules (HEVs) are found primarily in lymph nodes or formed de novo in peripheral tissues during inflammatory responses. They express peripheral node addressin (PNAd), which is recognized by the monoclonal antibody MECA79.

METHODS

Here, we demonstrated that HEVs form de novo in human pancreatic ductal adenocarcinoma (PDAC). We engineered MECA79 coated nanoparticles (MECA79-NPs) that recognize these ectopic HEVs in PDAC.

FINDINGS

The trafficking of MECA79-NPs following intravenous delivery to human PDAC implanted in a humanized mouse model was more robust than non-conjugated NPs. Treatment with MECA79-Taxol-NPs augmented the delivery of Paclitaxel (Taxol) to the tumor site and significantly reduced the tumor size. This effect was associated with a higher apoptosis rate of PDAC cells and reduced vascularization within the tumor.

INTERPRETATION

Targeting the HEVs of PDAC using MECA79-NPs could lay the ground for the localized delivery of a wide variety of drugs including chemotherapeutic agents. FUND: National Institutes of Health (NIH) grants: T32-EB016652 (B·B.), NIH Cancer Core Grant CA034196 (L.D.S.), National Institute of Allergy and Infectious Diseases grants R01-AI126596 and R01-HL141815 (R.A.).

Lipid nanoparticles with minimum burst release of TNF-α siRNA show strong activity against rheumatoid arthritis unresponsive to methotrexate

TNF-α siRNA has shown promising therapeutic benefits in animal models of rheumatoid arthritis. However, there continues to be a need for siRNA delivery systems that have high siRNA encapsulation efficiency and minimum burst release of TNF-α siRNA, and can target inflamed tissues after intravenous administration. Herein we report a novel acid-sensitive sheddable PEGylated solid-lipid nanoparticle formulation of TNF-α-siRNA, AS-TNF-α-siRNA-SLNs, prepared by incorporating lipophilized TNF-α-siRNA into solid-lipid nanoparticles composed of biocompatible lipids such as lecithin and cholesterol. The nanoparticles are approximately 120 nm in diameter, have a high siRNA encapsulation efficiency (>90%) and a minimum burst release of siRNA (<5%), and increase the deilvery of the siRNA in chronic inflammation sites in mouse models, including in a mouse model with collagen-induced arthritis. Importantly, in a mouse model of collagen antibody-induced arthritis that does not respond to methotrexate therapy, intravenous injection of the AS-TNF-α-siRNA-SLNs significantly reduced paw thickness, bone loss, and histopathological scores. These findings highlight the potential of using this novel siRNA nanoparticle formulation to effectively treat arthritis, potentially in patients who do not respond adequately to methotrexate.

Overcoming tumor cell chemoresistance using nanoparticles: lysosomes are beneficial for (stearoyl) gemcitabine-incorporated solid lipid nanoparticles

Despite recent advances in targeted therapies and immunotherapies, chemotherapy using cytotoxic agents remains an indispensable modality in cancer treatment. Recently, there has been a growing emphasis in using nanomedicine in cancer chemotherapy, and several nanomedicines have already been used clinically to treat cancers. There is evidence that formulating small molecular cancer chemotherapeutic agents into nanomedicines significantly modifies their pharmacokinetics and often improves their efficacy. Importantly, cancer cells often develop resistance to chemotherapy, and formulating anticancer drugs into nanomedicines also helps overcome chemoresistance. In this review, we briefly describe the different classes of cancer chemotherapeutic agents, their mechanisms of action and resistance, and evidence of overcoming the resistance using nanomedicines. We then emphasize on gemcitabine and our experience in discovering the unique (stearoyl) gemcitabine solid lipid nanoparticles that are effective against tumor cells resistant to gemcitabine and elucidate the underlying mechanisms. It seems that lysosomes, which are an obstacle in the delivery of many drugs, are actually beneficial for our (stearoyl) gemcitabine solid lipid nanoparticles to overcome tumor cell resistance to gemcitabine.

Pancreatic Cancer Chemoresistance to Gemcitabine

Pancreatic ductal adenocarcinoma (PDAC), commonly referred to as pancreatic cancer, ranks among the leading causes of cancer-related deaths in the Western world due to disease presentation at an advanced stage, early metastasis and generally a very limited response to chemotherapy or radiotherapy. Gemcitabine remains a cornerstone of PDAC treatment in all stages of the disease despite suboptimal clinical effects primarily caused by molecular mechanisms limiting its cellular uptake and activation and overall efficacy, as well as the development of chemoresistance within weeks of treatment initiation. To circumvent gemcitabine resistance in PDAC, several novel therapeutic approaches, including chemical modifications of the gemcitabine molecule generating numerous new prodrugs, as well as new entrapment designs of gemcitabine in colloidal systems such as nanoparticles and liposomes, are currently being investigated. Many of these approaches are reported to be more efficient than the parent gemcitabine molecule when tested in cellular systems and in vivo in murine tumor model systems; however, although promising, their translation to clinical use is still in a very early phase. This review discusses gemcitabine metabolism, activation and chemoresistance entities in the gemcitabine cytotoxicity pathway and provides an overview of approaches to override chemoresistance in pancreatic cancer.

Combination of using prodrug-modified cationic liposome nanocomplexes and a potentiating strategy via targeted co-delivery of gemcitabine and docetaxel for CD44-overexpressed triple negative breast cancer therapy

In this study, novel prodrug-modified cationic liposome nanocomplexes (Combo NCs) were reported for gemcitabine (GEM) and docetaxel (DTX) co-delivery. This nanoplatform exhibited multiple favorable characteristics, such as a 'green' fabrication with a one-step chemical reaction, appropriate size (∼200nm) and distribution (PDI<0.2), low zeta potential (-31.1mv), high drug-loading efficiency (9.3% GEM plus 3.1% DTX, wt%) and pH and enzymatic dual-stimulus-responsive release properties. Immunofluorescence and cellular uptake studies showed that Combo NCs efficiently targeted overexpressed CD44 in MDA-MB-231 carcinoma. In vitro studies revealed that Combo NCs played a critical role in the synergistic induction of cytotoxicity, apoptosis and inhibition of wound healing. Combo NCs were confirmed to exhibit great potency for increasing S phase arrest and remodeling the CDA and dCK balance by decreasing the mRNA expression of CDA down to 0.09-fold and increasing the mRNA expression of dCK by 1.36-fold, remarkably increasing the dCK/CDA ratio to 15.3-fold compared with the blank control. The biodistribution results obtained in vivo revealed an effective accumulation in tumor foci. All of these advantages of Combo NCs contributed to their remarkable anti-tumor efficacy without systemic toxicity as well as their apoptosis-enhancing and anti-proliferative capacities, as determined by TUNEL and Ki67 immunohistochemistry in vivo. Consequently, such a rationally contemplated co-delivery system demonstrated the promising potential of clinical applications for triple-negative breast cancer therapy.

STATE OF SIGNIFICANCE

The Combo NCs were innovatively applied for co-delivery of hydrophilic GEM and hydrophobic DTX. The ester bond linking and shielding effect of HA-GEM made the carriers achieve synchronous release properties, which was determined in in vitro release study. Due to the HA modification, the vectors own great potency for positive targeting to CD44 overexpressed triple-negative breast cancer cells MDA-MB-231. Cytotoxicity and apoptosis studies confirmed the targeting effect and synergism between two drugs. Interestingly, we found in cell cycle study, drug combinations (free combination or Combo NCs) didn't show a rise in G2M phase, which was significantly higher when treated DTX alone. We further discovered the role of DTX in combinations may involve in modulating GEM associated enzymes thus enhancing the efficacy of GEM. Consequently, this nanoplatform provided a novel solution for achieving targeted co-delivery and potentiating effect in cancer therapy.

Phase-Separated Liposomes Enhance the Efficiency of Macromolecular Delivery to the Cellular Cytoplasm

INTRODUCTION

From viruses to organelles, fusion of biological membranes is used by diverse biological systems to deliver macromolecules across membrane barriers. Membrane fusion is also a potentially efficient mechanism for the delivery of macromolecular therapeutics to the cellular cytoplasm. However, a key shortcoming of existing fusogenic liposomal systems is that they are inefficient, requiring a high concentration of fusion-promoting lipids in order to cross cellular membrane barriers.

OBJECTIVES

Toward addressing this limitation, our experiments explore the extent to which membrane fusion can be amplified by using the process of lipid membrane phase separation to concentrate fusion-promoting lipids within distinct regions of the membrane surface.

METHODS

We used confocal fluorescence microscopy to investigate the integration of fusion-promoting lipids into a ternary lipid membrane system that separated into liquid-ordered and liquid-disordered membrane phases. Additionally, we quantified the impact of membrane phase separation on the efficiency with which liposomes transferred lipids and encapsulated macromolecules to cells, using a combination of confocal fluorescence imaging and flow cytometry.

RESULTS

Here we report that concentrating fusion-promoting lipids within phase-separated lipid domains on the surfaces of liposomes significantly increases the efficiency of liposome fusion with model membranes and cells. In particular, membrane phase separation enhanced the delivery of lipids and model macromolecules to the cytoplasm of tumor cells by at least 4-fold in comparison to homogenous liposomes.

CONCLUSIONS

Our findings demonstrate that phase separation can enhance membrane fusion by locally concentrating fusion-promoting lipids on the surface of liposomes. This work represents the first application of lipid membrane phase separation in the design of biomaterials-based delivery systems. Additionally, these results lay the ground work for developing fusogenic liposomes that are triggered by physical and molecular cues associated with target cells.

Lipid-Drug Conjugate for Enhancing Drug Delivery

Lipid-drug conjugates (LDCs) are drug molecules that have been covalently modified with lipids. The conjugation of lipids to drug molecules increases lipophilicity and also changes other properties of drugs. The conjugates demonstrate several advantages including improved oral bioavailability, improved targeting to the lymphatic system, enhanced tumor targeting, and reduced toxicity. Based on the chemical nature of drugs and lipids, various conjugation strategies and chemical linkers can be utilized to synthesize LDCs. Linkers and/or conjugation methods determine how drugs are released from LDCs and are critical for the optimal performance of LDCs. In this review, different lipids used for preparing LDCs and various conjugation strategies are summarized. Although LDCs can be administered without a delivery carrier, most of them are loaded into appropriate delivery systems. The lipid moiety in the conjugates can significantly enhance drug loading into hydrophobic components of delivery carriers and thus generate formulations with high drug loading and superior stability. Different delivery carriers such as emulsions, liposomes, micelles, lipid nanoparticles, and polymer nanoparticles are also discussed in this review.

Synthesis, Characterization, and In Vitro and In Vivo Evaluations of 4-(N)-Docosahexaenoyl 2', 2'-Difluorodeoxycytidine with Potent and Broad-Spectrum Antitumor Activity

In this study, a new compound, 4-(N)-docosahexaenoyl 2′, 2′-difluorodeoxycytidine (DHA-dFdC), was synthesized and characterized. Its antitumor activity was evaluated in cell culture and in mouse models of pancreatic cancer. DHA-dFdC is a poorly soluble, pale yellow waxy solid, with a molecular mass of 573.3 Da and a melting point of about 96°C. The activation energy for the degradation of DHA-dFdC in an aqueous Tween 80–based solution is 12.86 kcal/mol, whereas its stability is significantly higher in the presence of vitamin E. NCI-60 DTP Human Tumor Cell Line Screening revealed that DHA-dFdC has potent and broad-spectrum antitumor activity, especially in leukemia, renal, and central nervous system cancer cell lines. In human and murine pancreatic cancer cell lines, the IC₅₀ value of DHA-dFdC was up to 10⁵-fold lower than that of dFdC. The elimination of DHA-dFdC in mouse plasma appeared to follow a biexponential model, with a terminal phase t_1/2 of about 58 minutes. DHA-dFdC significantly extended the survival of genetically engineered mice that spontaneously develop pancreatic ductal adenocarcinoma. In nude mice with subcutaneously implanted human Panc-1 pancreatic tumors, the antitumor activity of DHA-dFdC was significantly stronger than the molar equivalent of dFdC alone, DHA alone, or the physical mixture of them (1:1, molar ratio). DHA-dFdC also significantly inhibited the growth of Panc-1 tumors orthotopically implanted in the pancreas of nude mice, whereas the molar equivalent dose of dFdC alone did not show any significant activity. DHA-dFdC is a promising compound for the potential treatment of cancers in organs such as the pancreas.

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.

Acid-Sensitive Sheddable PEGylated PLGA Nanoparticles Increase the Delivery of TNF-α siRNA in Chronic Inflammation Sites

There has been growing interest in utilizing small interfering RNA (siRNA) specific to pro-inflammatory cytokines, such as tumor necrosis factor-α ( TNF-α), in chronic inflammation therapy. However, delivery systems that can increase the distribution of the siRNA in chronic inflammation sites after intravenous administration are needed. Herein we report that innovative functionalization of the surface of siRNA-incorporated poly (lactic-co-glycolic) acid (PLGA) nanoparticles significantly increases the delivery of the siRNA in the chronic inflammation sites in a mouse model. The TNF-α siRNA incorporated PLGA nanoparticles were prepared by the standard double emulsion method, but using stearoyl-hydrazone-polyethylene glycol 2000, a unique acid-sensitive surface active agent, as the emulsifying agent, which renders (i) the nanoparticles PEGylated and (ii) the PEGylation sheddable in low pH environment such as that in chronic inflammation sites. In a mouse model of lipopolysaccharide-induced chronic inflammation, the acid-sensitive sheddable PEGylated PLGA nanoparticles showed significantly higher accumulation or distribution in chronic inflammation sites than PLGA nanoparticles prepared with an acid-insensitive emulsifying agent (i.e., stearoyl-amide-polyethylene glycol 2000) and significantly increased the distribution of the TNF-α siRNA incorporated into the nanoparticles in inflamed mouse foot.

Tumor-Associated Macrophage-Mediated Targeted Therapy of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive form of breast cancer. TNBC is often infiltrated with a large number of macrophages, which in turn promote tumor growth and metastasis. In this study, tumor-associated macrophages (TAMs) were exploited as a target to deliver doxorubicin (DOX), a chemotherapeutic agent, to TNBC using nanoparticles surface-functionalized by (i) acid-sensitive sheddable PEGylation and (ii) modifying with mannose (i.e., DOX-AS-M-PLGA-NPs). In mice with orthotopic M-Wnt triple-negative mammary tumors, a single intravenous injection of DOX-AS-M-PLGA-NPs significantly reduced macrophage population in tumors within 2 days, and the density of the macrophages recovered slowly. Repeated injections of DOX-AS-M-PLGA-NPs can help maintain the population of the macrophages at a lower level. In M-Wnt tumor-bearing mice that were pretreated with zoledronic acid to nonselectively deplete macrophages, the TAM-targeting DOX-AS-M-PLGA-NPs were not more effective than the DOX-AS-PLGA-NPs that were not surface-modified with mannose and thus do not target TAMs in controlling tumor growth. However, in M-Wnt tumor-bearing mice that were not pretreated with zoledronic acid, the TAM-targeting DOX-AS-M-PLGA-NPs were significantly more effective than the nontargeting DOX-AS-PLGA-NPs in controlling the tumor growth. The AS-M-PLGA-NPs or other nanoparticles surface-functionalized similarly, when loaded with a chemotherapeutic agent commonly used in adjuvant therapy of TNBC, may be developed into targeted therapy for TNBC.

Development and evaluation of well-tolerated and tumor-penetrating polymeric micelle-based dry powders for inhaled anti-cancer chemotherapy

Despite the direct access to the lung offered by the inhalation route, drug penetration into lung tumors could remain an important issue. In this study, folate-polyethylene glycol-hydrophobically-modified dextran (F-PEG-HMD) micelles were developed as an effective pulmonary drug delivery system to reach and penetrate lung tumors and cancer cells. The F-PEG-HMD micelles were able to enter HeLa and M109-HiFR, two folate receptor-expressing cancer cell lines, in vitro, and in vivo after administration by inhalation to orthotopic M109-HiFR lung tumor grafted mice. Paclitaxel-loaded F-PEG-HMD micelles characterized in PBS by a Z-average diameter of ∼50 nm and a zeta potential of ∼-4 mV were prepared with an encapsulation efficiency of ∼100%. The loaded micelles reduced HeLa and M109-HiFR cell growth, with half maximal inhibitory concentrations of 37 and 150 nM, respectively. Dry powders embedding the paclitaxel-loaded F-PEG-HMD micelles were developed by spray-drying. In vitro, good deposition profiles were obtained, with a fine particle fraction of up to 50% and good ability to re-disperse the micelles in physiological buffer. A polymeric micelle-based dry powder without paclitaxel was well-tolerated in vivo, as assessed in healthy mice by determination of total protein content, cell count, and cytokine IL-1β, IL-6, and TNF-α concentrations in bronchoalveolar lavage fluids.

Synthesis and characterization of TPGS–gemcitabine prodrug micelles for pancreatic cancer therapy

Evaluation of a novel polymer-drug conjugate formulation in pancreatic cancer.

Development and validation of a stability indicating isocratic HPLC method for gemcitabine with application to drug release from poly lactic-co-glycolic acid nanoparticles and enzymatic degradation studies

Objectives

Previously reported HPLC methods for gemcitabine determination are time-consuming with complicated mobile phases and gradient elution. Thus, a sensitive and stability-indicating isocratic HPLC method, which provides simple, fast and precise measurements, was developed. This method was applied to study the digestive enzymatic degradation of gemcitabine, for the first time, and the protection afforded following incorporation into poly lactic-co-glycolic acid (PLGA) nanoparticles.

Methods

An analytical HPLC method was developed with an optimized combination of operating conditions. Forced degradation and application of the method to in-vitro drug release studies were conducted. Finally, gemcitabine-loaded nanoparticles were exposed to the digestive enzymes pepsin, trypsin and α-chymotrypsin, and the resulting degradation evaluated.

Key findings

The analytical method was linear between 1 and 100 μg/ml, with excellent accuracy of 99.91–101.77% and precision of 1.71 or lower, with a 0.014 μg/ml limit of detection (LOD) and a 0.043 μg/ml limit of quantification (LOQ). Following exposure of gemcitabine to stressors, the drug was relatively stable in strong acid (1 N HCl), base (1 N NaOH) and as an aqueous solution exposed to light over 7 days, with less than 10% degradation. However, gemcitabine was more susceptible to degradation at 70°C and oxidative conditions (3% v/v H2O2) with greater than 10% degradation noted after 7 days. In-vitro drug release studies demonstrated a sustained drug release profile from PLGA nanoparticles, which also improved the resistance of gemcitabine to enzymatic degradation.

Conclusion

These results demonstrate the utility and effectiveness of this simple isocratic HPLC method in evaluating the overall performance of a gemcitabine-loaded formulation.

[Role of RRM1 in the Treatment and Prognosis of Advanced Non-small Cell Lung Cancer]

Lung cancer is one of the most common and highest mortality rates malignant tumors, further, 75%-80% is non-small cell lung cancer (NSCLC). For the majority of patients, lost the chance of radical operation or radiotherapy, chemotherapy is the main treatment. However, because of the diversities of tumor behavior and drug-resistant, the chemotherapy of advanced NSCLC is not optimistic. In recent years, with the application of molecular markers for individual chemotherapy, these patients have achieved prolong life and improved life quality. Individualized chemotherapy based on molecular markers to select the appropriate drug is the problem that needs to be solved. The paper gives a brief review on the role of ribonucleotide reductase subunit 1 (RRM1) in the treatment and prognosis of advanced NSCLC. Individualized chemotherapy by RRM1 can't become commonplace for advanced NSCLC and needs further research.

Engineering of lipid prodrug-based, hyaluronic acid-decorated nanostructured lipid carriers platform for 5-fluorouracil and cisplatin combination gastric cancer therapy

PURPOSE

The first-line chemotherapy treatment protocol for gastric cancer is combination chemotherapy of 5-fluorouracil (5-FU) and cisplatin (CDDP). The aim of this study was to engineer prodrug-based nanostructured lipid carriers (NLC) platform for codelivery of 5-FU and CDDP to enhance therapy and decrease toxicity.

METHODS

First, 5-FU-stearic acid lipid conjugate was synthesized by two steps. Second, 5-FU-stearic acid prodrug and CDDP were loaded in NLC. Finally, hyaluronic acid (HA) was coated onto NLC surface. Average size, zeta potential, and drug loading capacity of NLC were evaluated. Human gastric cancer cell line BGC823 (BGC823 cells) was used for the testing of in vitro cytotoxicity assays. In vivo antitumor activity of NLC was evaluated in mice bearing BGC823 cells model.

RESULTS

HA-coated 5-FU-stearic acid prodrug and CDDP-loaded NLC (HA-FU/C-NLC) showed a synergistic effect in combination therapy and displayed the greatest antitumor activity than all of the free drugs or uncoated NLC in vitro and in vivo.

CONCLUSION

This work reveals that HA-coated NLC could be used as a novel carrier to code-liver 5-FU and CDDP for gastric cancer therapy. HA-FU/C-NLC could be a promising targeted and combinational therapy in nanomedicine.

Biodistribution and in vivo activities of tumor-associated macrophage-targeting nanoparticles incorporated with doxorubicin

Tumor-associated macrophages (TAMs) are increasingly considered a viable target for tumor imaging and therapy. Previously, we reported that innovative surface-functionalization of nanoparticles may help target them to TAMs. In this report, using poly(lactic-co-glycolic) acid (PLGA) nanoparticles incorporated with doxorubicin (DOX) (DOX-NPs), we studied the effect of surface-modification of the nanoparticles with mannose and/or acid-sensitive sheddable polyethylene glycol (PEG) on the biodistribution of DOX and the uptake of DOX by TAMs in tumor-bearing mice. We demonstrated that surface-modification of the DOX-NPs with both mannose and acid-sensitive sheddable PEG significantly increased the accumulation of DOX in tumors, enhanced the uptake of the DOX by TAMs, but decreased the distribution of DOX in mononuclear phagocyte system (MPS), such as liver. We also confirmed that the acid-sensitive sheddable PEGylated, mannose-modified DOX-nanoparticles (DOX-AS-M-NPs) targeted TAMs because depletion of TAMs in tumor-bearing mice significantly decreased the accumulation of DOX in tumor tissues. Furthermore, in a B16-F10 tumor-bearing mouse model, we showed that the DOX-AS-M-NPs were significantly more effective than free DOX in controlling tumor growth but had only minimum effect on the macrophage population in mouse liver and spleen. The AS-M-NPs are promising in targeting cytotoxic or macrophage-modulating agents into tumors to improve tumor therapy.

Enhanced effect of pH-sensitive mixed copolymer micelles for overcoming multidrug resistance of doxorubicin

P-glycoprotein (P-gp) mediated drug efflux has been recognized as a key factor contributing to the multidrug resistance (MDR) in tumor cells. To address this issue, a new pH-sensitive mixed copolymer micelles system composed of hyaluronic acid-g-poly(l-histidine) (HA-PHis) and d-α-tocopheryl polyethylene glycol 2000 (TPGS2k) copolymers was developed to co-deliver doxorubicin (DOX) and TPGS2k into drug-resistant breast cancer MCF-7 cells (MCF-7/ADR). The DOX-loaded HA-PHis/TPGS2k mixed micelles (HPHM/TPGS2k) were characterized to have a unimodal size distribution, high DOX loading content and a pH dependent drug release profile due to the protonation of poly(l-histidine). As compared to HA-PHis micelles (HPHM), the HPHM/TPGS2k showed higher and comparable cytotoxicity against MCF-7/ADR cells and MCF-7 cells, respectively. The enhanced MDR reversal effect was attributed to the higher amount of cellular uptake of HPHM/TPGS2k in MCF-7/ADR cells than HPHM, arising from the inhibition of P-gp mediated drug efflux by TPGS2k. The measurements of P-gp expression level and mitochondrial membrane potential indicate that the blank HPHM/TPGS2k inhibited P-gp activity by reducing mitochondrial membrane potential and depletion of ATP but without inhibition of P-gp expression. In vivo study of micelles in tumor-bearing mice indicate that HPHM/TPGS2k could reach the tumor site more effectively than HPHM. The pH-sensitive mixed micelles system has been demonstrated to be a promising approach for overcoming the MDR.

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.

Potential applications of nanotechnology for the diagnosis and treatment of pancreatic cancer

Despite improvements in our understanding of pancreatic cancer and the emerging concept of personalized medicine for the treatment of this disease, it is still the fourth most common cause of cancer death in the western world. It is established that pancreatic cancer is a highly heterogeneous disease with a complex tumor microenvironment. Indeed the extensive stroma surrounding the cancer cells has been shown to be important in promoting tumor growth and metastases, as well as sequestering chemotherapeutic agents consequently decreasing delivery to the tumor cells. Nanotechnology has come to the forefront in the areas of medical diagnostics, imaging, and therapeutic drug delivery. This review will focus on the potential applications of nanotechnology for diagnosis, imaging, and delivery of therapeutic agents for the treatment of pancreatic cancer.

Targeting of tumor-associated macrophages made possible by PEG-sheddable, mannose-modified nanoparticles

It is increasingly evident that tumor-associated macrophages (TAMs) play an important role in tumor invasion, proliferation, and metastasis. While delivery of drugs, imaging agents, and vaccines to TAMs was achieved by exploiting membrane receptors on TAMs, the uptake by normal macrophages remains an issue. In this communication, we report a PEG-sheddable, mannose-modified nanoparticle platform that can efficiently target TAMs via mannose-mannose receptor recognition after acid-sensitive PEG shedding in the acidic tumor microenvironment, while their uptake by normal macrophages in the mononuclear phagocyte system (MPS) organs was significantly reduced due to effective PEG shielding at neutral pH. These nanoparticles have the potential to target drugs of interest to TAMs, with decreased uptake by normal macrophages.

Just getting into cells is not enough: mechanisms underlying 4-(N)-stearoyl gemcitabine solid lipid nanoparticle's ability to overcome gemcitabine resistance caused by RRM1 overexpression

Gemcitabine is a deoxycytidine analog that is widely used in the chemotherapy of many solid tumors. However, acquired tumor cell resistance often limits its use. Previously, we discovered that 4-(N)-stearoyl gemcitabine solid lipid nanoparticles (4-(N)-GemC18-SLNs) can overcome multiple acquired gemcitabine resistance mechanisms, including RRM1 overexpression. The present study was designed to elucidate the mechanisms underlying the 4-(N)-GemC18-SLNs' ability to overcome gemcitabine resistance. The 4-(N)-GemC18 in the 4-(N)-GemC18-SLNs entered tumor cells due to clathrin-mediated endocytosis of the 4-(N)-GemC18-SLNs into the lysosomes of the cells, whereas the 4-(N)-GemC18 alone in solution entered cells by diffusion. We substantiated that it is the way the 4-(N)-GemC18-SLNs deliver the 4-(N)-GemC18 into tumor cells that allows the gemcitabine hydrolyzed from the 4-(N)-GemC18 to be more efficiently converted into its active metabolite, gemcitabine triphosphate (dFdCTP), and thus more potent against gemcitabine-resistant tumor cells than 4-(N)-GemC18 or gemcitabine alone. Moreover, we also showed that the RRM1-overexpressing tumor cells were also cross-resistant to cytarabine, another nucleoside analog commonly used in cancer therapy, and 4-(N)-stearoyl cytarabine carried by solid lipid nanoparticles can also overcome the resistance. Therefore, formulating the long-chain fatty acid amide derivatives of nucleoside analogs into solid lipid nanoparticles may represent a platform technology to increase the antitumor activity of the nucleoside analogs and to overcome tumor cell resistance to them.