Sialic acid-modified docetaxel cationic liposomes: double targeting of tumor-associated macrophages and tumor endothelial cells

Taxane drugs are clinically used for the treatment of many types of cancers due to their excellent antitumor effects. However, the surfactants contained in the injections currently used in the clinic may have serious toxic side effects on the organism, making it necessary to develop new dosage forms. Cationic liposomes have been widely used in antitumor research because of their advantage of preferentially targeting tumor neovascularization, but antitumor by targeting tumor vasculature alone does not necessarily provide good results. Malignant tumors represent complex ecosystems, tumor-associated macrophages (TAMs) and tumor endothelial cells (TECs) in the tumor microenvironment play crucial roles in tumor growth. Therefore, given the ability to achieve active targeting of TAMs and TECs by using sialic acid (SA) as a targeting material, the potential of cationic nanoformulations to preferentially target neovascularization at the tumor site, and the excellent antitumor effects of the taxane drugs docetaxel (DOC), in the present study, sialic acid-cholesterol coupling (SA-CH) was selected as a targeting material to prepare a DOC cationic liposome (DOC-SAL) for tumor therapy. The results of the study showed that DOC-SAL had the strongest drug accumulation in tumor tissues compared with the common DOC formulations, and was able to effectively reduce the colonization of TAMs, inhibit the proliferation of tumor cells, and have the best tumor-suppressing effect. In addition, DOC-SAL was able to improve the internal microenvironment of tumors by modulating cytokines. In summary, this drug delivery system has good anti-tumor effects and provides a new option for tumor therapy.

Endothelial Cell Adhesion Molecules- (un)Attainable Targets for Nanomedicines

Endothelial cell adhesion molecules have long been proposed as promising targets in many pathologies. Despite promising preclinical data, several efforts to develop small molecule inhibitors or monoclonal antibodies (mAbs) against cell adhesion molecules (CAMs) ended in clinical-stage failure. In parallel, many well-validated approaches for targeting CAMs with nanomedicine (NM) were reported over the years. A wide range of potential applications has been demonstrated in various preclinical studies, from drug delivery to the tumor vasculature, imaging of the inflamed endothelium, or blocking immune cells infiltration. However, no NM drug candidate emerged further into clinical development. In this review, we will summarize the most advanced examples of CAM-targeted NMs and juxtapose them with known traditional drugs against CAMs, in an attempt to identify important translational hurdles. Most importantly, we will summarize the proposed strategies to enhance endothelial CAM targeting by NMs, in an attempt to offer a catalog of tools for further development.

Anti-inflammatory and anti-arthritic effects of pentacyclic triterpenoids maslinic acid through NF-κB inactivation

SCOPE

Consumption of olives (Olea europaea L.), including table olives and oil, is associated with low incidence of inflammation-related diseases. In this study, the effects of maslinic acid (MA), the main constituent of olive pomace, on the expression of genes and proteins involved in inflammatory activity in RAW 264.7 cells were investigated. Furthermore, the effect of MA on carrageenan-induced paw edema and collagen antibody induced arthritis in mice was determined.

METHODS AND RESULTS

We confirmed the suppressive effects of MA on LPS-induced tumor necrosis factor α production and on the expression of inflammatory response associated genes in RAW 264.7 cells. We also clarified the suppressive effect of MA on LPS-induced nuclear factor-kappa B activation as well as the phosphorylation of IκB-α. Furthermore, MA (200 mg/kg in the edema model or 100 mg/kg in the arthritis model) exerted anti-inflammatory and antiarthritis effects as shown by the suppression of paw edema, arthritis score, inflammatory cells, and destruction of synovium in knee joints.

CONCLUSION

Olive products containing MA are useful as a new preventive and therapeutic food ingredient for inflammatory and arthritic diseases.

A carbohydrate-grafted nanovesicle with activatable optical and acoustic contrasts for dual modality high performance tumor imaging

Activatable molecular systems enabling precise tumor localization are valuable for complete tumor resection. Herein, we report sialic acid-capped polymeric nanovesicles encapsulating the near infrared profluorophore (pNIR@P@SA) for lysosome activation based dual modality tumor imaging. The probe features surface-anchored sialic acid for tumor targeting and a core of near infrared profluorophore (pNIR) which undergoes lysosomal acidity triggered isomerization to give optical and optoacoustic signals upon cell internalization. Imaging studies reveal high-efficiency uptake and signal activation of pNIR@P@SA in subcutaneous tumors and millimeter-sized liver tumor foci in mice. The high tumor-to-healthy organ signal contrasts and discernment of tiny liver tumors from normal liver tissues validate the potential of pNIR@P@SA for high performance optical and optoacoustic imaging guided tumor resection.

Nanomedicine for drug targeting: strategies beyond the enhanced permeability and retention effect

The growing research interest in nanomedicine for the treatment of cancer and inflammatory-related pathologies is yielding encouraging results. Unfortunately, enthusiasm is tempered by the limited specificity of the enhanced permeability and retention effect. Factors such as lack of cellular specificity, low vascular density, and early release of active agents prior to reaching their target contribute to the limitations of the enhanced permeability and retention effect. However, improved nanomedicine designs are creating opportunities to overcome these problems. In this review, we present examples of the advances made in this field and endeavor to highlight the potential of these emerging technologies to improve targeting of nanomedicine to specific pathological cells and tissues.

A platelet-inspired paradigm for nanomedicine targeted to multiple diseases

Platelets are megakaryocyte-derived anucleated cells found in the blood. They are mainly responsible for rendering hemostasis or clotting to prevent bleeding complications. Decreased platelet numbers or deficiencies in platelet functions can lead to various acute or chronic bleeding conditions and hemorrhage. On the other hand, dysregulated hyperactivity of the clotting process can lead to thrombosis and vascular occlusion. There is significant evidence that beyond hemostasis and thrombosis, platelets play crucial mechanistic roles in other disease scenarios such as inflammation, immune response and cancer metastasis by mediating several cell-cell and cell-matrix interactions, as well as aiding the disease microenvironment via secretion of multiple soluble factors. Therefore, elucidating these mechanistic functions of platelets can provide unique avenues for developing platelet-inspired nanomedicine strategies targeted to these diseases. To this end, the current review provides detailed mechanistic insight into platelets' disease-relevant functions and discusses how these mechanisms can be utilized to engineer targeted nanomedicine systems.

Development of liposomal nanoconstructs targeting P-selectin (CD62P)-expressing cells by using a sulfated derivative of sialic acid

PURPOSE

NMSO3, a sulfated derivative of sialic acid, is a specific inhibitor for P-selectin (CD62P)-mediated cell adhesion. We attempted to apply liposomes modified with NMSO3 for selective targeting of activated platelets.

METHODS

The binding of fluorescently labeled NMSO3-containing liposomes (NMSO3-liposomes) to CHO cells expressing P-selectin (CHO-P cells) and activated platelets were examined. The distribution of NMSO3-liposomes incorporated into the cells was observed by fluorescence microscopy.

RESULTS

The binding assay revealed that NMSO3-liposomes specifically bound to immobilized P-selectin and CHO-P cells in a dose-dependent manner. The binding of NMSO3-liposomes to CHO-P cells was much stronger than that to the parental CHO-K1 cells. Fluorescence microscopic observation showed that NMSO3-liposomes were incorporated into CHO-P cells after the binding and distributed throughout the cytoplasm of the cell. NMSO3-liposomes bound more strongly to thrombin-activated platelets than to resting platelets, as assessed by flow cytometry.

CONCLUSIONS

These results suggest that NMSO3-liposomes can be applied for selective drug delivery to activated platelets.

A multichannel acoustically driven microfluidic chip to study particle-cell interactions

Microfluidic devices have emerged as important tools for experimental physiology. They allow to study the effects of hydrodynamic flow on physiological and pathophysiological processes, e.g., in the circulatory system of the body. Such dynamic in vitro test systems are essential in order to address fundamental problems in drug delivery and targeted imaging, such as the binding of particles to cells under flow. In the present work an acoustically driven microfluidic platform is presented in which four miniature flow channels can be operated in parallel at distinct flow velocities with only slight inter-experimental variations. The device can accommodate various channel architectures and is fully compatible with cell culture as well as microscopy. Moreover, the flow channels can be readily separated from the surface acoustic wave pumps and subsequently channel-associated luminescence, absorbance, and/or fluorescence can be determined with a standard microplate reader. In order to create artificial blood vessels, different coatings were evaluated for the cultivation of endothelial cells in the microchannels. It was found that 0.01% fibronectin is the most suitable coating for growth of endothelial monolayers. Finally, the microfluidic system was used to study the binding of 1 μm polystyrene microspheres to three different types of endothelial cell monolayers (HUVEC, HUVECtert, HMEC-1) at different average shear rates. It demonstrated that average shear rates between 0.5 s(-1) and 2.25 s(-1) exert no significant effect on cytoadhesion of particles to all three types of endothelial monolayers. In conclusion, the multichannel microfluidic platform is a promising device to study the impact of hydrodynamic forces on cell physiology and binding of drug carriers to endothelium.

E-selectin as a target for drug delivery and molecular imaging

E-selectin, also known as CD62E, is a cell adhesion molecule expressed on endothelial cells activated by cytokines. Like other selectins, it plays an important part in inflammation and in the adhesion of metastatic cancer cells to the endothelium. E-selectin recognizes and binds to sialylated carbohydrates present on the surface proteins of certain leukocytes. E-selectin has been chosen as a target for several therapeutic and medical imaging applications, based on its expression in the vicinity of inflammation, infection or cancer. These systems for drug delivery and molecular imaging include immunoconjugates, liposomes, nanoparticles, and microparticles prepared from a wide range of starting materials including lipids, synthetic polymers, polypeptides and organo-metallic structures. After a brief introduction presenting the selectin family and their implication in physiology and pathology, this review focuses on the formulation of these new delivery systems targeting E-selectin at a molecular level.

Development of an active targeting liposome encapsulated with high-density colloidal gold for transmission electron microscopy

Active targeting of the liposome is an attractive strategy for drug delivery and in vivo bio-imaging. We previously reported the specific accumulation of Sialyl Lewis X (SLX) liposome to inflamed tissue in arthritic model mice or tumor-bearing mice. SLX-liposome encapsulation with fluorescent substances allows for the visualization of these liposomes by the time-dependent transvascular accumulation of fluorescent signals in the histological sections. In the present study, we developed a new SLX-liposome encapsulated with colloidal gold for transmission electron microscopic observation. We herein describe the characterization of the colloidal gold-loaded SLX-liposomes and demonstrate its specific targeting to the endothelial cells of tumor blood vessels in tumor-bearing mice.

Targeted drug-delivery approaches by nanoparticulate carriers in the therapy of inflammatory diseases

Limitations in therapy induced by adverse effects due to unselective drug availability and therefore the use of potentially too high doses are a common problem. One prominent example for this dilemma are inflammatory diseases. Colloidal carriers allow one to improve delivery of drugs to the site of action and appear promising to overcome this general therapeutic drawback. Specific uptake of nanoparticles by immune-related cells in inflamed barriers offers selective drug targeting to the inflamed tissue. Here we focus on nanocarrier-based drug delivery strategies for the treatment of common inflammatory disorders like rheumatoid arthritis, multiple sclerosis, uveitis or inflammatory bowel disease.