Alternate routes for drug delivery to the cell interior: pathways to the Golgi apparatus and endoplasmic reticulum

Sequential Targeting Chondroitin Sulfate-Bilirubin Nanomedicine Attenuates Osteoarthritis via Reprogramming Lipid Metabolism in M1 Macrophages

The infiltration and excessive polarization of M1 macrophages contribute to the induction and persistence of low-grade inflammation in joint-related degenerative diseases such as osteoarthritis (OA). The lipid metabolism dysregulation promotes M1 macrophage polarization by coordinating the compensatory pathways of the inflammatory and oxidative stress responses. Here, a self-assembling, licofelone-loaded nanoparticle (termed LCF-CSBN), comprising chondroitin sulfate and bilirubin joined by an ethylenediamine linker, is developed to selectively reprogram lipid metabolism in macrophage activation. LCF-CSBN is internalized by M1 macrophages via CD44-mediated endocytosis and targets the Golgi apparatus accompanied with the reactive oxygen species-responsive release of licofelone (LCF, dual inhibitor of arachidonic acid metabolism). LCF-CSBN effectively promotes M1 to M2 macrophage transition by reprogramming the Golgi apparatus-related sphingolipid metabolism and arachidonic acid metabolism. Intra-articularly injected LCF-CSBN retains in the joint for up to 28 days and accumulates into M1 macrophages. Moreover, LCF-CSBN can effectively attenuate joint inflammation, oxidative stress, and cartilage degeneration in OA model rats. These findings indicate the promising potential of lipid-metabolism-reprogramming LCF-CSBN in the targeted therapy of OA.

Monosaccharide coating modulate the intracellular trafficking of gold nanoparticles in dendritic cells

Dendritic cells (DCs) have emerged as a promising target for drug delivery and immune modulation due to their pivotal role in initiating the adaptive immune response. Gold nanoparticles (AuNPs) have garnered interest as a platform for targeted drug delivery due to their biocompatibility, low toxicity and precise control over size, morphology and surface functionalization. Our investigation aimed to elucidate the intracellular uptake and trafficking of AuNPs coated with different combinations of monosaccharides (mannose, galactose, and fucose) in DCs. We used 30 unique polymer-tethered monosaccharide combinations to coat 16 nm diameter spherical gold nanoparticles and investigated their effect on DCs phenotype, uptake, and intracellular trafficking. DCs internalized AuNPs coated with 100 % fucose, 100 % mannose, 90 % mannose +10 % galactose, and 80 % mannose +20 % galactose with highest efficiency. Flow cytometry analysis indicated that 100 % fucose-coated AuNPs showed increased lysosomal and endosomal contents compared to other conditions and uncoated AuNPs. Imaging flow cytometry further demonstrated that 100 % fucose-coated AuNPs had enhanced co-localization with lysosomes, while 100 % mannose-coated AuNPs exhibited higher co-localization with endosomes. Furthermore, our data showed that the uptake of carbohydrate-coated AuNPs predominantly occurred through receptor-mediated endocytosis, as evidenced by a marked reduction of uptake upon treatment of DCs with methyl-β-cyclodextrins, known to disrupt receptor-mediated endocytosis. These findings highlight the utility of carbohydrate coatings to enable more targeted delivery of nanoparticles and their payload to distinct intracellular compartments in immune cells with potential applications in drug delivery and immunotherapy.

Nanomaterials in Medicine: Understanding Cellular Uptake, Localization, and Retention for Enhanced Disease Diagnosis and Therapy

Nanomaterials (NMs) have emerged as promising tools for disease diagnosis and therapy due to their unique physicochemical properties. To maximize the effectiveness and design of NMs-based medical applications, it is essential to comprehend the complex mechanisms of cellular uptake, subcellular localization, and cellular retention. This review illuminates the various pathways that NMs take to get from the extracellular environment to certain intracellular compartments by investigating the various mechanisms that underlie their interaction with cells. The cellular uptake of NMs involves complex interactions with cell membranes, encompassing endocytosis, phagocytosis, and other active transport mechanisms. Unique uptake patterns across cell types highlight the necessity for customized NMs designs. After internalization, NMs move through a variety of intracellular routes that affect where they are located subcellularly. Understanding these pathways is pivotal for enhancing the targeted delivery of therapeutic agents and imaging probes. Furthermore, the cellular retention of NMs plays a critical role in sustained therapeutic efficacy and long-term imaging capabilities. Factors influencing cellular retention include nanoparticle size, surface chemistry, and the cellular microenvironment. Strategies for prolonging cellular retention are discussed, including surface modifications and encapsulation techniques. In conclusion, a comprehensive understanding of the mechanisms governing cellular uptake, subcellular localization, and cellular retention of NMs is essential for advancing their application in disease diagnosis and therapy. This review provides insights into the intricate interplay between NMs and biological systems, offering a foundation for the rational design of next-generation nanomedicines.

Targeting the Inside of Cells with Biologicals: Toxin Routes in a Therapeutic Context

Numerous toxins translocate to the cytosol in order to fulfil their function. This demonstrates the existence of routes for proteins from the extracellular space to the cytosol. Understanding these routes is relevant to multiple aspects related to therapeutic applications. These include the development of anti-toxin treatments, the potential use of toxins as shuttles for delivering macromolecular cargo to the cytosol or the use of drugs based on toxins. Compared with other strategies for delivery, such as chemicals as carriers for macromolecular delivery or physical methods like electroporation, toxin routes present paths into the cell that potentially cause less damage and can be specifically targeted. The efficiency of delivery via toxin routes is limited. However, low-delivery efficiencies can be entirely sufficient, if delivered cargoes possess an amplification effect or if very few molecules are sufficient for inducing the desired effects. This is known for example from RNA-based vaccines that have been developed during the coronavirus disease 2019 pandemic as well as for other approved RNA-based drugs, which elicited the desired effect despite their typically low delivery efficiencies. The different mechanisms by which toxins enter cells may have implications for their technological utility. We review the mechanistic principles of the translocation pathway of toxins from the extracellular space to the cytosol, the delivery efficiencies, and therapeutic strategies or applications that exploit toxin routes for intracellular delivery.

Design Strategies of Tumor-Targeted Delivery Systems Based on 2D Nanomaterials

Conventional chemotherapy and radiotherapy are nonselective and nonspecific for cell killing, causing serious side effects and threatening the lives of patients. It is of great significance to develop more accurate tumor-targeting therapeutic strategies. Nanotechnology is in a leading position to provide new treatment options for cancer, and it has great potential for selective targeted therapy and controlled drug release. 2D nanomaterials (2D NMs) have broad application prospects in the field of tumor-targeted delivery systems due to their special structure-based functions and excellent optical, electrical, and thermal properties. This review emphasizes the design strategies of tumor-targeted delivery systems based on 2D NMs from three aspects: passive targeting, active targeting, and tumor-microenvironment targeting, in order to promote the rational application of 2D NMs in clinical practice.

Chondroitin sulfate-based prodrug nanoparticles enhance photodynamic immunotherapy via Golgi apparatus targeting

Photodynamic therapy (PDT) is an emerging therapeutic approach that can inhibit tumor growth by destroying local tumors and activating systemic antitumor immune responses. However, PDT can be ineffective because of photosensitizer aggregation, tumor-induced dendritic cells (DC_S) dysfunction and PDT-mediated immunosuppression. Therefore, we designed chondroitin sulfate-based prodrug nanoparticles for the co-delivery of the photosensitizer chlorin e6 (Ce6) and retinoic acid (RA), which can reduce PDT-mediated immunosuppression by disrupting the Golgi apparatus and blocking the production of immunosuppressive cytokines. Moreover, CpG oligodeoxynucleotide was combined as immunoadjuvant to promote the maturation of DCs. As expected, the strategy of Golgi apparatus targeting immunotherapy combined PDT was confirmed to relieve PDT-induced immunosuppression, showed excellent PDT antitumor efficacy in B16F10-subcutaneous bearing mice model. Thus, our finding offers a promising approach for photodynamic immunotherapy of advanced cancers. STATEMENT OF SIGNIFICANCE: Golgi apparatus has been shown to be a potential target of immunosuppression for producing several immunosuppressive cytokines. In this work, a Golgi apparatus-targeted prodrug nanoparticle was developed to enhance the immune response in photodynamic immunotherapy. The nanoparticle can target and disrupt the Golgi apparatus in tumor cells, which reduced PDT-mediated immunosuppression by blocking the production of immunosuppressive cytokines. This work provides an effective strategy of PDT in combination with the Golgi apparatus-targeted nanovesicle for enhanced cancer therapy.

pH-sensitive nanoliposomes for passive and CXCR-4-mediated marine yessotoxin delivery for cancer therapy

Background: Yessotoxin (YTX), a marine-derived drug, was encapsulated in PEGylated pH-sensitive nanoliposomes, covalently functionalized (strategy I) with SDF-1α and by nonspecific adsorption (strategy II), to actively target chemokine receptor CXCR-4. Methods: Cytotoxicity to normal human epithelial cells (HK-2) and prostate (PC-3) and breast (MCF-7) adenocarcinoma models, with different expression levels of CXCR-4, were tested. Results: Strategy II exerted the highest cytotoxicity toward cancer cells while protecting normal epithelia. Acid pH-induced fusion of nanoliposomes seemed to serve as a primary route of entry into MCF-7 cells but PC-3 data support an endocytic pathway for their internalization. Conclusion: This work describes an innovative hallmark in the current marine drug clinical pipeline, as the developed nanoliposomes are promising candidates in the design of groundbreaking marine flora-derived anticancer nanoagents.

The Bradykinin B2 Receptor Agonist (NG291) Causes Rapid Onset of Transient Blood-Brain Barrier Disruption Without Evidence of Early Brain Injury

Background: The blood-brain barrier (BBB) describes the brain's highly specialized capillaries, which form a dynamic interface that maintains central nervous system (CNS) homeostasis. The BBB supports the CNS, in part, by preventing the entry of potentially harmful circulating molecules into the brain. However, this specialized function is challenging for the development of CNS therapeutics. Several strategies to facilitate drug delivery into the brain parenchyma via disruption of the BBB have been proposed. Bradykinin has proven effective in disrupting mechanisms across the blood-tumor barrier. Unfortunately, bradykinin has limited therapeutic value because of its short half-life and the undesirable biological activity elicited by its active metabolites. Objective: To evaluate NG291, a stable bradykinin analog, with selective agonist activity on the bradykinin-B2 receptor and its ability to disrupt the BBB transiently. Methods: Sprague Dawley rats and CD-1 mice were subjected to NG291 treatment (either 50 or 100 μg/kg, intravenously). Time and dose-dependent BBB disruption were evaluated by histological analysis of Evans blue (EB) extravasation. Transcellular and paracellular BBB leakage were assessed by infiltration of 99mTc-albumin (66.5 KDa) and 14C-sucrose (340 Da) radiolabeled probes into the brains of CD-1 mice treated with NG291. NG291 influence on P-glycoprotein (P-gp) efflux pump activity was evaluated by quantifying the brain accumulation of 3H-verapamil, a known P-gp substrate, in CD-1 mice. Results: NG291-mediated BBB disruption was localized, dose-dependent, and reversible as measured by EB extravasation. 99mTc-albumin leakage was significantly increased by 50 μg/kg of NG291, whereas 100 μg/kg of NG291 significantly augmented both 14C-sucrose and 99mTc-albumin leakage. NG291 enhanced P-gp efflux transporter activity and was unable to increase brain uptake of the P-gp substrate pralidoxime. NG291 did not evoke significant short-term neurotoxicity, as it did not increase brain water content, the number of Fluoro-Jade C positive cells, or astrocyte activation. Conclusion: Our findings strongly suggest that NG291 increases BBB permeability by two different mechanisms in a dose-dependent manner and increases P-gp efflux transport. This increased permeability may facilitate the penetration into the brain of therapeutic candidates that are not P-gp substrates.

An Integrative Pan-Cancer Analysis of the Oncogenic Role of COPB2 in Human Tumors

Several studies have suggested that coatomer protein complex subunit beta 2 (COPB2) may act as an oncogene in various cancer types. However, no systematic pan-cancer analysis has been performed to date. Therefore, the present study analyzed the potential oncogenic role of COPB2 using TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus) datasets. The majority of the cancer types overexpressed the COPB2 protein, and its expression significantly correlated with tumor prognosis. In certain tumors, such as those found in breast and ovarian tissues, phosphorylated S859 exhibited high expression. It was found that mutations of the COPB2 protein in kidney and endometrial cancers exhibited a significant impact on patient prognosis. It is interesting to note that COPB2 expression correlated with the number of cancer-associated fibroblasts in certain tumors, such as cervical and endocervical cancers and colon adenocarcinomas. In addition, COPB2 was involved in the transport of substances and correlated with chemotherapy sensitivity. This is considered the first pan-tumor study, which provided a relatively comprehensive understanding of the mechanism by which COPB2 promotes cancer growth.

Potential therapies and diagnosis based on Golgi-targeted nano drug delivery systems

With the rapid development of nanotechnology, organelle-targeted nano drug delivery systems (NDDSs) have emerged as a potential method which can transport drugs specifically to the subcellular compartments like nucleus, mitochondrion, lysosome, endoplasmic reticulum (ER) and Golgi apparatus (GA). GA not only plays a key role in receiving, modifying, packaging and transporting proteins and lipids, but also contributes to a set of cellular processes. Golgi-targeted NDDSs can alter the morphology of GA and will become a promising strategy with high specificity, low-dose administration and decreased occurrence of side effects. In this review, Golgi-targeted NDDSs and their applications in disease therapies and diagnosis such as cancer, metastasis, fibrosis and neurological diseases are introduced. Meanwhile, modifications of NDDSs to achieve targeting strategies, Golgi-disturbing agents to change the morphology of GA, special endocytosis to achieve endosomal/lysosomal escape strategies are also involved.

Polyarginine-Mediated siRNA Delivery: A Mechanistic Study of Intracellular Trafficking of PCL-R15/siRNA Nanoplexes

As a cell-penetrating peptide, polyarginine is widely used in drug delivery systems based on its membrane permeation ability. Previously, we developed the mPEG-PLA-b-polyarginine(R15) triblock copolymer, which exhibited a high siRNA delivery efficiency both in vitro and in vivo. As a continued effort, here the amphiphilic diblock polymer PCL-R15 was synthesized as a simplified model to further elucidate the structure-activity relationship of arginine-based amphiphilic polymers as siRNA delivery systems, and the cellular trafficking mechanisms of the PCL-R15/siRNA nanoplexes were investigated to understand the interaction patterns between the nanoplexes and cells. Compared to the R15/siRNA complexes, the introduction of PCL moiety was found to result in the stronger interactions with cells and the enhanced transfection efficiency after the formation of condensed nanoplexes. Caveolae-mediated endocytosis and clathrin-mediated endocytosis were major routes for the internalization of PCL-R15/siRNA nanoplexes. The intracellular release of siRNA from nanoplexes was confirmed by fluorescence resonance energy transfer assay. It was also noticed that the internalized PCL-R15/siRNA nanoplexes were transported through digestive routes and trapped in lysosomes, which may be the bottleneck for efficient siRNA delivery of PCL-R15/siRNA nanoplexes. This study investigated the relationship between the polymer structure of PCL-R15 and the cellular interaction patterns, which may render implications on the rational design of polyarginine-based siRNA delivery systems.

Chondroitin Sulfate-Linked Prodrug Nanoparticles Target the Golgi Apparatus for Cancer Metastasis Treatment

Metastasis is a multistep biological process regulated by multiple signaling pathways. The integrity of the Golgi apparatus plays an important role in these signaling pathways. Inspired by the mechanism and our previous finding about accumulation of chondroitin sulfate in Golgi apparatus in hepatic stellate cells, we developed a Golgi apparatus-targeting prodrug nanoparticle system by synthesizing retinoic acid (RA)-conjugated chondroitin sulfate (CS) (CS-RA). The prodrug nanoparticles appeared to accumulate in the Golgi apparatus in cancer cells and realized RA release under an acidic environment. We confirmed that CS-RA exhibited successful inhibition of multiple metastasis-associated proteins expression in vitro and in vivo by disruption of the Golgi apparatus structure. Following loading with paclitaxel (PTX), the CS-RA based nanoformulation (PTX-CS-RA) inhibited migration, invasion, and angiogenesis in vitro and suppressed tumor growth and metastasis in 4T1-Luc bearing mice. This multistep targeted nanoparticle system potentially enhanced the effect of antimetastasis combined with chemotherapy.

Intracellular drug delivery: Potential usefulness of engineered Shiga toxin subunit B for targeted cancer therapy

A treasure trove of intracellular cancer drug targets remains hidden behind cell membranes. However, engineered pathogen-derived toxins such as Shiga toxins can deliver small or macromolecular drugs to specific intracellular organelles. After binding to ganglioglobotriaosylceramide (Gb3, CD77), the non-toxic subunit B (StxB) of the Shiga-holotoxin is endocytosed and delivers its payload by a unique retrograde trafficking pathway via the endoplasmic reticulum to the cytosol. This review provides an overview of biomedical applications of StxB-based drug delivery systems in targeted cancer diagnosis and therapy. Biotechnological production of the Stx-material is discussed from the perspective of developing efficacious and safe therapeutics.

Downregulation of vimentin expression increased drug resistance in ovarian cancer cells

Cisplatin and other platinum-based drugs have been widely used in the treatment of ovarian cancer, but most patients acquire the drug resistance that greatly compromises the efficacy of drugs. Understanding the mechanism of drug resistance is important for finding new therapeutic approaches. In the present study, we found that the expression of vimentin was downregulated in drug-resistant ovarian cancer cell lines A2780-DR and HO-8910 as compared to their respective control cells. Overexpression of vimentin in A2780-DR cells markedly increased their sensitivity to cisplatin, whereas knockdown of vimentin in A2780, HO-8910-PM and HO-8910 cells increased the resistance to cisplatin, demonstrating that vimentin silencing enhanced cisplatin resistance in ovarian cancer cells. Quantitative proteomic analysis identified 95 differentially expressed proteins between the vimentin silenced A2780 cells (A2780-VIM-KN) and the control cells, in which downregulation of endocytic proteins and the upregulation of exocytotic proteins CHMP2B and PDZK1 were proposed to contribute the decreased cisplatin accumulation in vimentin knockdown cells. Silencing of vimentin induced upregulation of cancer stem cell markers and both A2780-DR and A2780-VIM-KN cells were more facile to form spheroids than control cells under serum-free culture condition. Our results also revealed that vimentin knockdown increased the 14-3-3 mediated retention of Cdc25C in the cytoplasm, leading to inactivation of Cdk1 and the prolonged G2 phase arrest that allowed the longer period of time for cells to repair cisplatin-damaged DNA. Taken together, we demonstrated that vimentin silencing enhanced cells' resistance to cisplatin via prolonged G2 arrest and increased exocytosis, suggesting that vimentin is a potential target for treatment of drug resistant ovarian cancer.

Targeting superoxide dismutase to endothelial caveolae profoundly alleviates inflammation caused by endotoxin

Inflammatory mediators binding to Toll-Like receptors (TLR) induce an influx of superoxide anion in the ensuing endosomes. In endothelial cells, endosomal surplus of superoxide causes pro-inflammatory activation and TLR4 agonists act preferentially via caveolae-derived endosomes. To test the hypothesis that SOD delivery to caveolae may specifically inhibit this pathological pathway, we conjugated SOD with antibodies (Ab/SOD, size ~10nm) to plasmalemmal vesicle-associated protein (Plvap) that is specifically localized to endothelial caveolae in vivo and compared its effects to non-caveolar target CD31/PECAM-1. Plvap Ab/SOD bound to endothelial cells in culture with much lower efficacy than CD31 Ab/SOD, yet blocked the effects of LPS signaling with higher efficiency than CD31 Ab/SOD. Disruption of cholesterol-rich membrane domains by filipin inhibits Plvap Ab/SOD endocytosis and LPS signaling, implicating the caveolae-dependent pathway(s) in both processes. Both Ab/SOD conjugates targeted to Plvap and CD31 accumulated in the lungs after IV injection in mice, but the former more profoundly inhibited LPS-induced pulmonary inflammation and elevation of plasma level of interferon-beta and -gamma and interleukin-27. Taken together, these results indicate that targeted delivery of SOD to specific cellular compartments may offer effective, mechanistically precise interception of pro-inflammatory signaling mediated by reactive oxygen species.

Design of an Anticancer Copper(II) Prodrug Based on the Lys199 Residue of the Active Targeting Human Serum Albumin Nanoparticle Carrier

We not only modified the types and numbers of coordinated ligands in a metal agent to enhance its anticancer activity, but we also designed a metal prodrug based on the N-donor residues of the human serum albumin (HSA) IIA subdomain to improve its delivery efficiency and selectivity in vivo. However, there may be a conflict in simultaneously achieving the two goals because Lys199 and His242 in the IIA subdomain of HSA can replace its two coordinated ligands, which will decrease its anticancer activity relative to the original metal agent. Thus, to improve the delivery efficiency of the metal agent and simultaneously avoid decreasing its anticancer activity in vivo, we decided to develop an anticancer metal prodrug by regulating its pharmacophore ligand so that it would not be displaced by the Lys199 residue of the folic acid (FA)-functionalized HSA nanoparticle (NP) carrier. To this end, we first synthesized two (E)-N'-(5-chloro-2-hydroxybenzylidene)benzohydrazide Schiff base (HL) Cu(II) compounds by designing a second ligand with a different coordinating atom with Cu²⁺/Cu(L)(QL)(Br) [C1, QL = quinolone] and Cu(L)(DMF)(Br) [C2, DMF = N,N-dimethylformamide]. As revealed by the structures of the two HSA complexes, the Cu compounds bind to the hydrophobic cavity in the HSA IIA subdomain. The QL ligand of C1 is replaced by Lys199, which coordinates with Cu²⁺, whereas the DMF ligand of C2 is kept intact and His242 is replaced with Br^- of C2 and coordinates with Cu²⁺. The cytotoxicity of the Cu compounds was enhanced by the FA-HSA NPs in the Bel-7402 cells approximately 2-4-fold; however, they raise the cytotoxicity levels in the normal cells in vitro, and the FA-HSA NPs did not. Importantly, the in vivo data showed that FA-HSA-C2 NPs increased selectivity and the capacity to inhibit tumor growth and were less toxic than HSA-C2 NPs and C2. Moreover, C2/HSA-C2 NPs/FA-HSA-C2 NPs induced Bel-7402 cell death by potentially multiple mechanisms.

Non-Viral Nucleic Acid Delivery Strategies to the Central Nervous System

With an increased prevalence and understanding of central nervous system (CNS) injuries and neurological disorders, nucleic acid therapies are gaining promise as a way to regenerate lost neurons or halt disease progression. While more viral vectors have been used clinically as tools for gene delivery, non-viral vectors are gaining interest due to lower safety concerns and the ability to deliver all types of nucleic acids. Nevertheless, there are still a number of barriers to nucleic acid delivery. In this focused review, we explore the in vivo challenges hindering non-viral nucleic acid delivery to the CNS and the strategies and vehicles used to overcome them. Advantages and disadvantages of different routes of administration including: systemic injection, cerebrospinal fluid injection, intraparenchymal injection and peripheral administration are discussed. Non-viral vehicles and treatment strategies that have overcome delivery barriers and demonstrated in vivo gene transfer to the CNS are presented. These approaches can be used as guidelines in developing synthetic gene delivery vectors for CNS applications and will ultimately bring non-viral vectors closer to clinical application.

Membrane associated cancer-oocyte neoantigen SAS1B/ovastacin is a candidate immunotherapeutic target for uterine tumors

The metalloproteinase SAS1B [ovastacin, ASTL, astacin-like] was immunolocalized on the oolemma of ovulated human oocytes and in normal ovaries within the pool of growing oocytes where SAS1B protein was restricted to follicular stages spanning the primary-secondary follicle transition through ovulation. Gene-specific PCR and immunohistochemical studies revealed ASTL messages and SAS1B protein in both endometrioid [74%] and malignant mixed Mullerian tumors (MMMT) [87%] of the uterus. A MMMT-derived cell line, SNU539, expressed cell surface SAS1B that, after binding polyclonal antibodies, internalized into EEA1/LAMP1-positive early and late endosomes. Treatment of SNU539 cells with anti-SAS1B polyclonal antibodies caused growth arrest in the presence of active complement. A saporin-immunotoxin directed to SAS1B induced growth arrest and cell death. The oocyte restricted expression pattern of SAS1B among adult organs, cell-surface accessibility, internalization into the endocytic pathway, and tumor cell growth arrest induced by antibody-toxin conjugates suggest therapeutic approaches that would selectively target tumors while limiting adverse drug effects in healthy cells. The SAS1B metalloproteinase is proposed as a prototype cancer-oocyte tumor surface neoantigen for development of targeted immunotherapeutics with limited on-target/off tumor effects predicted to be restricted to the population of growing oocytes.

A systematic High-Content Screening microscopy approach reveals key roles for Rab33b, OATL1 and Myo6 in nanoparticle trafficking in HeLa cells

Synthetic nanoparticles are promising tools for imaging and drug delivery; however the molecular details of cellular internalization and trafficking await full characterization. Current knowledge suggests that following endocytosis most nanoparticles pass from endosomes to lysosomes. In order to design effective drug delivery strategies that can use the endocytic pathway, or by-pass lysosomal accumulation, a comprehensive understanding of nanoparticle uptake and trafficking mechanisms is therefore fundamental. Here we describe and apply an RNA interference-based high-content screening microscopy strategy to assess the intracellular trafficking of fluorescently-labeled polystyrene nanoparticles in HeLa cells. We screened a total of 408 genes involved in cytoskeleton and membrane function, revealing roles for myosin VI, Rab33b and OATL1 in this process. This work provides the first systematic large-scale quantitative assessment of the proteins responsible for nanoparticle trafficking in cells, paving the way for subsequent genome-wide studies.

Cellular uptake of exogenous calcineurin B is dependent on TLR4/MD2/CD14 complexes, and CnB is an endogenous ligand of TLR4

Our previous research showed that recombinant calcineurin B (rhCnB) stimulates cytokine secretion by immune cells, probably through TLR4. Exogenous CnB can be incorporated into many different tumour cells in vitro, but the mode of uptake and receptors required remain unknown. Here, we report that exogenous CnB is taken up by cells in a time- and concentration-dependent manner via clathrin-dependent receptor-mediated internalization. Our findings further confirm that uptake is mediated by the TLR4/MD2 complex together with the co-receptor CD14. The MST results revealed a high affinity between CnB and the TLR4 receptor complex. No binding was detected between CnB and LPS. CnB inhibited the uptake of LPS, and LPS also inhibited the uptake of CnB. These results indicate that the uptake of exogenous CnB did not occur through LPS and that CnB was not a chaperone of LPS. Thus, we conclude that TLR4 receptor complexes were required for the recognition and internalization of exogenous CnB. CnB could be a potential endogenous ligand of TLR4 and function as an agonist of TLR4. These properties of CnB support its potential for development as an anti-cancer drug.

Cellular Endocytosis and Trafficking of Cholera Toxin B-Modified Mesoporous Silica Nanoparticles

In this study, mesoporous silica nanoparticles (MSNs) were functionalized with Cholera toxin subunit B (CTxB) protein to influence their intracellular trafficking pathways. The CTxB-MSN carrier was synthesized, and its chemical and structural properties were characterized. Endocytic pathway inhibition assays showed that the uptake of CTxB-MSNs in human cervical cancer (HeLa) cells was partially facilitated by both chlatrin- and caveolae-mediated endocytosis mechanisms. Laser scanning confocal microscopy (LSCM) experiments demonstrated that CTxB-MSNs were taken up by the cells and partially trafficked through the trans-Golgi network into to the endoplasmic reticulum in a retrograde fashion. The delivery abilities of CTxB-MSNs were evaluated using propidium iodide, an impermeable cell membrane dye. LSCM images depicted the release of propidium iodide in the endoplasmic reticulum and cell nucleus of HeLa cells.

Multiple cues on the physiochemical, mesenchymal, and intracellular trafficking interactions with nanocarriers to maximize tumor target efficiency

Over the past 60 years, numerous medical strategies have been employed to overcome neoplasms. In fact, with the exception of lung, bronchial, and pancreatic cancers, the 5-year survival rate of most cancers currently exceeds 70%. However, the quality of life of patients during chemotherapy remains unsatisfactory despite the increase in survival rate. The side effects of current chemotherapies stem from poor target efficiency at tumor sites due to the uncontrolled biodistribution of anticancer agents (ie, conventional or current approved nanodrugs). This review discusses the effective physiochemical factors for determining biodistribution of nanocarriers and, ultimately, increasing tumor-targeting probability by avoiding the reticuloendothelial system. Second, stem cell-conjugated nanotherapeutics was addressed to maximize the tumor searching ability and to inhibit tumor growth. Lastly, physicochemical material properties of anticancer nanodrugs were discussed for targeting cellular organelles with modulation of drug-release time. A better understanding of suggested topics will increase the tumor-targeting ability of anticancer drugs and, ultimately, promote the quality of life of cancer patients during chemotherapy.

High-content analysis for drug delivery and nanoparticle applications

High-content analysis (HCA) provides quantitative multiparametric cellular fluorescence data. From its origins in discovery toxicology, it is now addressing fundamental questions in drug delivery. Nanoparticles (NPs), polymers, and intestinal permeation enhancers are being harnessed in drug delivery systems to modulate plasma membrane properties and the intracellular environment. Identifying comparative mechanistic cytotoxicity on sublethal events is crucial to expedite the development of such systems. NP uptake and intracellular routing pathways are also being dissected using chemical and genetic perturbations, with the potential to assess the intracellular fate of targeted and untargeted particles in vitro. As we discuss here, HCA is set to make a major impact in preclinical delivery research by elucidating the intracellular pathways of NPs and the in vitro mechanistic-based toxicology of formulation constituents.

Cellular uptake and in vitro antitumor efficacy of composite liposomes for neutron capture therapy

Background

Neutron capture therapy for glioblastoma has focused mainly on the use of ¹⁰B as neutron capture isotope. However, ¹⁵⁷Gd offers several advantages over boron, such as higher cross section for thermal neutrons and the possibility to perform magnetic resonance imaging during neutron irradiation, thereby combining therapy and diagnostics. We have developed different liposomal formulations of gadolinium-DTPA (Magnevist®) for application in neutron capture therapy of glioblastoma. The formulations were characterized physicochemically and tested in vitro in a glioma cell model for their effectiveness.

Methods

Liposomes entrapping gadolinium-DTPA as neutron capture agent were manufactured via lipid/film-extrusion method and characterized with regard to size, entrapment efficiency and in vitro release. For neutron irradiation, F98 and LN229 glioma cells were incubated with the newly developed liposomes and subsequently irradiated at the thermal column of the TRIGA reactor in Mainz. The dose rate derived from neutron irradiation with ¹⁵⁷Gd as neutron capturing agent was calculated via Monte Carlo simulations and set in relation to the respective cell survival.

Results

The liposomal Gd-DTPA reduced cell survival of F98 and LN229 cells significantly. Differences in liposomal composition of the formulations led to distinctly different outcome in cell survival. The amount of cellular Gd was not at all times proportional to cell survival, indicating that intracellular deposition of formulated Gd has a major influence on cell survival. The majority of the dose contribution arises from photon cross irradiation compared to a very small Gd-related dose.

Conclusions

Liposomal gadolinium formulations represent a promising approach for neutron capture therapy of glioblastoma cells. The liposome composition determines the uptake and the survival of cells following radiation, presumably due to different uptake pathways of liposomes and intracellular deposition of gadolinium-DTPA. Due to the small range of the Auger and conversion electrons produced in ¹⁵⁷Gd capture, the proximity of Gd-atoms to cellular DNA is a crucial factor for infliction of lethal damage. Furthermore, Gd-containing liposomes may be used as MRI contrast agents for diagnostic purposes and surveillance of tumor targeting, thus enabling a theranostic approach for tumor therapy.

Insight into nanoparticle cellular uptake and intracellular targeting

Collaborative efforts from the fields of biology, materials science, and engineering are leading to exciting progress in the development of nanomedicines. Since the targets of many therapeutic agents are localized in subcellular compartments, modulation of nanoparticle-cell interactions for efficient cellular uptake through the plasma membrane and the development of nanomedicines for precise delivery to subcellular compartments remain formidable challenges. Cellular internalization routes determine the post-internalization fate and intracellular localization of nanoparticles. This review highlights the cellular uptake routes most relevant to the field of non-targeted nanomedicine and presents an account of ligand-targeted nanoparticles for receptor-mediated cellular internalization as a strategy for modulating the cellular uptake of nanoparticles. Ligand-targeted nanoparticles have been the main impetus behind the progress of nanomedicines towards the clinic. This strategy has already resulted in remarkable progress towards effective oral delivery of nanomedicines that can overcome the intestinal epithelial barrier. A detailed overview of the recent developments in subcellular targeting as a novel platform for next-generation organelle-specific nanomedicines is also provided. Each section of the review includes prospects, potential, and concrete expectations from the field of targeted nanomedicines and strategies to meet those expectations.

Synthesis of nanobioconjugates with a controlled average number of biomolecules between 1 and 100 per nanoparticle and observation of multivalency dependent interaction with proteins and cells

Multivalency of nanoparticle and associated cooperative binding with biological interface is an important aspect in the development of nanoparticle based bioimaging probes. However, the preparation of such a nanobioconjugate with a controlled number of biomolecules per nanoparticle, typically between 1 and 100, is challenging. Here we report a generalized two-step bioconjugation method to prepare nanobioconjugates with a varied average number of biomolecules between 1 to 100 per nanoparticle that can be applied to different nanoparticles and biomolecules. Following this approach we have successfully synthesized quantum dot (QD) based bioconjugates with controlled average numbers of glucose or folate and found their number-dependent interaction with proteins and cells. We propose a method for exploiting the nanoparticle multivalency effect toward various biological interactions and preparing such nanobioconjugates for best performance.

Cellular uptake mechanisms of an antitumor ruthenium compound: the endosomal/lysosomal system as a target for anticancer metal-based drugs

Previous studies have described promising antitumor activity of an organometallic Ru(II) complex, η⁵-cyclopentadienyl(2,2'-bipyridyl)(triphenylphosphane) Ruthenium(II) triflate ([η⁵-C₅H₅)Ru(2,2'-bipyridyl)(PPh₃)][CF₃SO₃]) herein designated as TM34. Its broad spectrum of activity against a panel of human tumor cell lines and high antiproliferative efficiency prompted us to focus on its mode of action. We present herein results obtained with two human tumor cell lines A2780 and MDAMB231 on the compound distribution within the cell, the mechanism of its activity, and its cellular targets. The prospective metallodrug TM34 revealed: (a) fast antiproliferative effects even at short incubation times for both cell lines; (b) preferential localization at the cell membrane and cytosol; (c) cellular activity by a temperature-dependent process, probably macropinocytosis; (d) inhibition of a lysosomal enzyme, acid phosphatase, in a dose-dependent mode; and (e) disruption and vesiculation of the Golgi apparatus, which suggest the involvement of the endosomal/lysosomal system in its mode of action. These results are essential to elucidate the basis for the cytotoxic activity and mechanism of action of this Ru(II)(η⁵-cyclopentadienyl) complex.

Viewing Golgi structure and function from a different perspective--insights from electron tomography

Historically, ultrastructural investigations, which have focused on elucidating the biological idiosyncrasies of the Golgi apparatus, have tended towards oversimplified or fallacious hypotheses when postulating how the Golgi apparatus reorganizes itself both structurally and functionally to fulfill the plethora of cellular processes underpinned by this complex organelle. Key questions are still unanswered with regard to how changes in Golgi architecture correlate so reproducibly to changes in its functional priorities under different physiological conditions or experimental perturbations. This fact alone serves to highlight how the technical limitations associated with conventional two-dimensional imaging approaches employed in the past failed to adequately capture the extraordinary complexity of the Golgi's three-dimensional (3D) structure-now a hallmark of this challenging organelle. Consequently, this has hampered progress towards developing a clear understanding of how changes in its structure and function typically occur in parallel. In this chapter, we highlight but a few of the significant new insights regarding variations in the Golgi's structure-function relationships that have been afforded over recent years through advanced electron microscopic techniques for 3D image reconstruction, commonly referred to as electron tomography.

The effect of nanoparticle uptake on cellular behavior: disrupting or enabling functions?

Nanoparticles (NPs) are materials with overall dimensions in the nanoscale range. They have unique physicochemical properties, and have emerged as important players in current research in modern medicine. In the last few decades, several types of NPs and microparticles have been synthesized and proposed for use as contrast agents for diagnostics and imaging and for drug delivery; for example, in cancer therapy. Yet specific targeting that will improve their delivery still represents an unsolved challenge. The mechanism by which NPs enter the cell has important implications not only for their fate but also for their impact on biological systems. Several papers in the literature discuss the potential risks related to NP exposure, and more recently the concept that even sublethal doses of NPs may elicit a cell response has been proposed. In this review, we intend to present an overall view of cell mechanisms that may be perturbed by cell-NP interaction. Published data, in fact, emphasize that NPs should no longer be viewed only as simple carriers for biomedical applications, but that they can also play an active role in mediating biological effects.

Endocytosis and intracellular trafficking as gateways for nanomedicine delivery: opportunities and challenges

More than 40 nanomedicines are already in routine clinical use with a growing number following in preclinical and clinical development. The therapeutic objectives are often enhanced disease-specific targeting (with simultaneously reduced access to sites of toxicity) and, especially in the case of macromolecular biotech drugs, improving access to intracellular pharmacological target receptors. Successful navigation of the endocytic pathways is usually a prerequisite to achieve these goals. Thus a comprehensive understanding of endocytosis and intracellular trafficking pathways in both the target and bystander normal cell type(s) is essential to enable optimal nanomedicine design. It is becoming evident that endocytic pathways can become disregulated in disease and this, together with the potential changes induced during exposure to the nanocarrier itself, has the potential to significantly impact nanomedicine performance in terms of safety and efficacy. Here we overview the endomembrane trafficking pathways, discuss the methods used to determine and quantitate the intracellular fate of nanomedicines, and review the current status of lysosomotropic and endosomotropic delivery. Based on the lessons learned during more than 3 decades of clinical development, the need to use endocytosis-relevant clinical biomarkers to better select those patients most likely to benefit from nanomedicine therapy is also discussed.

Are Rab proteins the link between Golgi organization and membrane trafficking?

The fundamental separation of Golgi function between subcompartments termed cisternae is conserved across all eukaryotes. Likewise, Rab proteins, small GTPases of the Ras superfamily, are putative common coordinators of Golgi organization and protein transport. However, despite sequence conservation, e.g., Rab6 and Ypt6 are conserved proteins between humans and yeast, the fundamental organization of the organelle can vary profoundly. In the yeast Saccharomyces cerevisiae, the Golgi cisternae are physically separated from one another, while in mammalian cells, the cisternae are stacked one upon the other. Moreover, in mammalian cells, many Golgi stacks are typically linked together to generate a ribbon structure. Do evolutionarily conserved Rab proteins regulate secretory membrane trafficking and diverse Golgi organization in a common manner? In mammalian cells, some Golgi-associated Rab proteins function in coordination of protein transport and maintenance of Golgi organization. These include Rab6, Rab33B, Rab1, Rab2, Rab18, and Rab43. In yeast, these include Ypt1, Ypt32, and Ypt6. Here, based on evidence from both yeast and mammalian cells, we speculate on the essential role of Rab proteins in Golgi organization and protein transport.

Delivery of nanomedicines to extracellular and intracellular compartments of a solid tumor

Advances in molecular medicines have led to identification of promising targets on cellular and molecular levels. These targets are located in extracellular and intracellular compartments. The latter include cytosol, nucleus, mitochondrion, Golgi apparatus and endoplasmic reticulum. This report gives an overview on the barriers to delivering nanomedicines to various target sites within a solid tumor, the experimental approaches to overcome such barriers, and the potential utility of nanotechnology.

A subclass of acylated anti-inflammatory mediators usurp Toll-like receptor 2 to inhibit neutrophil recruitment through peroxisome proliferator-activated receptor gamma

Toll-like receptors are host sentinel receptors that signal the presence of infectious nonself and initiate protective immunity. One of the primary immune defense mechanisms is the recruitment of neutrophils from the bloodstream into the infected tissue. Although neutrophils are important in host defense, they can also be responsible for damaging pathologies associated with excessive inflammation. Here, we report that the di-acylated TLR2 ligand lipoteichoic acid can directly inhibit neutrophil recruitment in vivo. This discovery allowed us to test the concept that conventional proinflammatory TLR2 ligands can be made to act as inhibitors through specific structural modifications. Indeed, lipopeptide TLR2 ligands, when modified at their acyl chains to contain linoleate, lose their capacity to induce inflammation and yield ligands that can directly inhibit the in vivo neutrophil recruitment initiated by a wide range of proinflammatory stimuli. The inhibitory capacity of LTA and these modified ligands requires the expression of TLR2, but is independent of the TLR2 signaling adaptor, MyD88. Instead, this inhibitory effect requires functional activity of the fatty acid and nuclear hormone receptor peroxisome proliferator-activated receptor γ (PPARγ). Therefore, these data support a model in TLR2 biology where structural modifications of these ligands can profoundly influence host-microbial interactions. These inhibitory TLR2 ligands also have broader implications with respect to their potential use in various inflammatory disease settings.

Mechanisms controlling the cellular accumulation of copper bis(thiosemicarbazonato) complexes

Copper (Cu) bis(thiosemicarbazonato) metal complexes [Cu(II)(btsc)s] have unique tumor-imaging and treatment properties and more recently have revealed potent neuroprotective actions in animal and cell models of neurodegeneration. However, despite the continued development of Cu(II)(btsc)s as potential therapeutics or diagnostic agents, little is known of the mechanisms involved in cell uptake, subcellular trafficking, and efflux of this family of compounds. Because of their high lipophilicity, it has been assumed that cellular accumulation is through passive diffusion, although this has not been analyzed in detail. The role of efflux pathways in cell homeostasis of the complexes is also largely unknown. In the present study, we investigated the cellular accumulation of the Cu(II)(btsc) complexes Cu(II)(gtsm) and Cu(II)(atsm) in human neuronal (M17) and glial (U87MG) cell lines under a range of conditions. Collectively, the data strongly suggested that Cu(II)(gtsm) and Cu(II)(atsm) may be taken into these cells by combined passive and facilitated (protein-carrier-mediated) mechanisms. This was supported by strong temperature-dependent changes to the uptake of the complexes and the influence of the cell surface protein on Cu accumulation. We found no evidence to support a role for copper-transporter 1 in accumulation of the compounds. Importantly, our findings also demonstrated that Cu from both Cu(II)(gtsm) and Cu(II)(atsm) was rapidly effluxed from the cells through active mechanisms. Whether this was in the form of released ionic Cu or as an intact metal complex is not known. However, this finding highlighted the difficulty of trying to determine the uptake mechanism of metal complexes when efflux is occurring concomitantly. These findings are the first detailed exploration of the cellular accumulation mechanisms of Cu(II)(btsc)s. The study delineates strategies to investigate the uptake and efflux mechanisms of metal complexes in cells, while highlighting specific difficulties and challenges that need to be considered before drawing definitive conclusions.

The endosomal proteome of macrophage and dendritic cells

The essential roles of the endovacuolar system in health and disease call for the development of new tools allowing a better understanding of the complex molecular machinery involved in endocytic processes. We took advantage of the floating properties of small latex beads (sLB) on a discontinuous sucrose gradient to isolate highly purified endosomes following internalization of small latex beads in J774 macrophages and bone marrow-derived dendritic cells (DC). We particularly focused on the isolation of macrophages early endosomes and late endosomes/lysosomes (LE/LYS) as well as the isolation of LE/LYS from immature and lipopolysaccharide-activated (mature) DC. We subsequently performed a comparative analysis of their respective protein contents by MS. As expected, proteins already known to localize to the early endosomes were enriched in the earliest fraction of J774 endosomes, while proteins known to accumulate later in the process, such as hydrolases, were significantly enriched in the LE/LYS preparations. We next compared the LE/LYS protein contents of immature DC and mature DC, which are known to undergo massive reorganization leading to potent immune activation. The differences between the protein contents of endocytic organelles from macrophages and DC were underlined by focusing on previously poorly characterized biochemical pathways, which could have an unexpected but important role in the endosomal functions of these highly relevant immune cell types.

Synthesis and biological analysis of prostate-specific membrane antigen-targeted anticancer prodrugs

Ligand-targeted therapeutics have increased in prominence because of their potential for improved potency and reduced toxicity. However, with the advent of personalized medicine, a need for greater versatility in ligand-targeted drug design has emerged, where each tumor-targeting ligand should be capable of delivering a variety of therapeutic agents to the same tumor, each therapeutic agent being selected for its activity on a specific patient's cancer. In this report, we describe the use of a prostate-specific membrane antigen (PSMA)-targeting ligand to deliver multiple unrelated cytotoxic drugs to human prostate cancer (LNCaP) cells. We demonstrate that the PSMA-specific ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid, is capable of mediating the targeted killing of LNCaP cells with many different therapeutic warheads. These results suggest that flexibility can be designed into ligand-targeted therapeutics, enabling adaptation of a single targeting ligand for the treatment of patients with different sensitivities to different chemotherapies.

Formulation, characterization and optimization of hepatitis B surface antigen (HBsAg)-loaded chitosan microspheres for oral delivery

CONTEXT

Approximately 400 million persons worldwide have chronic hepatitis B. This is due to problems associated with vaccine delivery, stability and cost. Hence the present challenge in vaccinology is to develop safer, cheaper and easy-to-deliver forms of vaccines. A novel needle-free oral vaccine will be an ideal tool to fight this silent killer disease.

OBJECTIVE

The aim of this work was to prepare and evaluate chitosan-loaded HBsAg microspheres for oral delivery.

MATERIALS AND METHODS

Chitosan microspheres were prepared by emulsion solvent evaporation technique. To overcome the enzymatic and permeation barrier, protease inhibitors and permeation enhancers were also added. Studies were conducted to find the effect of stabilizer concentration, stirring speed, cross-linking agent and polymer concentration on microsphere size and entrapment efficiency. Formulations were characterized for their particle size, entrapment efficiency. They were also evaluated for the in vitro drug release, in vivo performances and the effect of different storage conditions.

RESULTS

HBsAg-loaded chitosan microspheres with bacitracin as protease inhibitor showed better protective levels of immunity after oral administration comparing with aprotinin as protease inhibitor. Stability at room temperature up to a period of four months reduces incomplete vaccine coverage and logistic requirements.

CONCLUSION

The study signifies the potential of the formulated chitosan microspheres for effective oral administration of HBsAg.

Structure, biological functions and applications of the AB5 toxins

AB(5) toxins are important virulence factors for several major bacterial pathogens, including Bordetella pertussis, Vibrio cholerae, Shigella dysenteriae and at least two distinct pathotypes of Escherichia coli. The AB(5) toxins are so named because they comprise a catalytic A-subunit, which is responsible for disruption of essential host functions, and a pentameric B-subunit that binds to specific glycan receptors on the target cell surface. The molecular mechanisms by which the AB(5) toxins cause disease have been largely unravelled, including recent insights into a novel AB(5) toxin family, subtilase cytotoxin (SubAB). Furthermore, AB(5) toxins have become a valuable tool for studying fundamental cellular functions, and are now being investigated for potential applications in the clinical treatment of human diseases.

Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications

Hydrogel nanoparticles—also referred to as polymeric nanogels or macromolecular micelles—are emerging as promising drug carriers for therapeutic applications. These nanostructures hold versatility and properties suitable for the delivery of bioactive molecules, namely of biopharmaceuticals. This article reviews the latest developments in the use of self-assembled polymeric nanogels for drug delivery applications, including small molecular weight drugs, proteins, peptides, oligosaccharides, vaccines and nucleic acids. The materials and techniques used in the development of self-assembling nanogels are also described.

Transgenic lettuce producing a candidate protein for vaccine against edema disease

Pig edema disease is a bacterial disease caused by Shiga toxin 2e-producing Escherichia coli belonging mainly to serotypes O138, O139, and O141. The B subunit of Shiga toxin 2e (Stx2eB) is a candidate protein for use in a vaccine against edema disease. We produced this protein in transgenic lettuce (Lactuca sativa), an edible plant that can be cultivated in a factory setting. In a transient expression system, we found that NtADH 5'-untranslated region (5'-UTR) functions as a translational enhancer in lettuce cells, and that Stx2eB accumulates most efficiently in the endoplasmic reticulum (ER) of lettuce cells. Stx2eB was produced in stable transgenic lettuce plants expressing a modified Stx2eB gene fused with the NtADH 5'-UTR and sequence encoding ER localization signals.

Tracing the retrograde route in protein trafficking

Retrograde transport, in which proteins and lipids are shuttled between endosomes and biosynthetic/secretory compartments such as the Golgi apparatus, is crucial for a diverse range of cellular functions. Mechanistic studies that explore the molecular machinery involved in this retrograde trafficking route are shedding light on the functions of transport proteins and are providing fresh insights into possible new therapeutic directions.