Current Drug Delivery - Volume 16, Issue 9, 2019

Bone diseases are a serious problem in modern human life. With the coming acceleration of global population ageing, this problem will become more and more serious. Due to the specific physiological characteristics and local microenvironment of bone tissue, it is difficult to deliver drugs to the lesion site. Therefore, the traditional orthopedic medicine scheme has the disadvantages of high drug frequency, large dose and relatively strong side effects. How to target deliver drugs to the bone tissue or even target cells is the focus of the development of new drugs. Nano drug delivery system with a targeting group can realize precise delivery of orthopedic drugs and effectively reduce the systemic toxicity. In addition, the application of bone tissue engineering scaffolds and biomedical materials to realize in situ drug delivery also are research hotspot. In this article, we briefly review the application of nanotechnology in targeted therapies for bone diseases.

Incretin contains two peptides named glucagon-like peptide-1(GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Drug therapy using incretin has become a new strategy for diabetic treatments due to its significant effects on improving insulin receptors and promoting insulinotropic secretion. Considering the fact that diabetes millitus is a key risk factor for almost all age-related diseases, the extensive protective roles of incretin in chronic diseases have received great attention. Based on the evidence from animal experiments, where incretin can protect against the pathophysiological processes of neurodegenerative diseases, clinical trials for the treatments of Alzheimer’s disease (AD) and Parkinson’s disease (PD) patients are currently ongoing. Moreover, the protective effect of incretin on heart has been observed in cardiac myocytes, smooth muscle cells and endothelial cells of vessels. Meanwhile, incretin can also inhibit the proliferation of aortic vascular smooth muscle cells, which can induce atherosclerogenesis. Incretin is also beneficial for diabetic microvascular complications, including nephropathy, retinopathy and gastric ulcer, as well as the hepatic-related diseases such as NAFLD and NASH. Besides, the anti-tumor properties of incretin have been proven in diverse cancers including ovarian cancer, pancreas cancer, prostate cancer and breast cancer.

Objectives: This study investigated the antitumor effect of a new nanomicellar complex obtained by combining the antitumor agent fenretinide with a quaternary amphiphilic amine RC16+ also endowed with antitumor activity. Methods: The complex (Fen-RC16+) strongly improved the aqueous solubility of fenretinide (from 1,71 ± 0.08 μg/ml, pure fenretinide to 1500 ± 164 μg /ml, Fen-RC16+ complex) and provided a cytotoxic effect on SH-SY5Y neuroblastoma cell lines resulting from the intrinsic activity of both the complex components. Moreover, the mean size of the nanomicellar complex (ranging from 20 ± 1.97 nm to 40 ± 3.05 nm) was suitable for accumulation to the tumor site by the enhanced permeability and retention effect and the positive charge provided by the quaternary RC16+ induced adsorption of the complex on the tumor cell surface improving the intracellular concentration of fenretinide. Results: All these characteristics made the Fen-RC16+ complex a multitasking system for antitumor therapy. Conclusion: Indeed its in vivo activity, evaluated on SH-SY5Y xenografts, was strong, and the tumor growth did not resume after the treatment withdrawal.

Objective: Novel vaccination approaches are required to control human immunodeficiency virus (HIV) infections. The membrane proximal external region (MPER) of Env gp41 subunit and the V3/glycans of Env gp120 subunit were known as potential antigenic targets for anti-HIV-1 vaccines. In this study, we prepared the modified dendritic cells (DCs) and mesenchymal stem cells (MSCs) with HIV-1 MPER-V3 gene using mechanical and chemical approaches. Methods: At first, MPER-V3 fusion DNA delivery was optimized in dendritic cells (DCs) and mesenchymal stem cells (MSCs) using three mechanical (i.e., uniaxial cyclic stretch, equiaxial cyclic stretch and shear stress bioreactors), and two chemical (i.e., TurboFect or Lipofectamine) methods. Next, the modified DCs and MSCs with MPER-V3 antigen were compared to induce immune responses in vivo. Results: Our data showed that the combination of equiaxial cyclic stretch loading and lipofectamine twice with 48 h intervals increased the efficiency of transfection about 60.21 ± 1.05 % and 65.06 ± 0.09 % for MSCs and DCs, respectively. Moreover, DCs and MSCs transfected with MPER-V3 DNA in heterologous DC or MSC prime/ peptide boost immunizations induced high levels of IgG2a, IgG2b, IFN-γ and IL-10 directed toward Th1 responses as well as an increased level of Granzyme B. Indeed, the modified MSCs and DCs with MPER-V3 DNA could significantly enhance the MPER/V3-specific T-cell responses compared to MPER/V3 peptide immunization. Conclusions: These findings showed that the modified MSC-based immunization could elicit effective immune responses against HIV antigen similar to the modified DC-based immunization.

Background: The co-encapsulation of paclitaxel (PTX) and doxorubicin (DXR) in liposomes has the potential to offer pharmacokinetic and pharmacodynamic advantages, providing delivery of both drugs to the tumor at the ratio required for synergism. Objective: To prepare and characterize long-circulating and fusogenic liposomes co-encapsulating PTX and DXR in the 1:10 molar ratio (LCFL-PTX/DXR). Methods: LCFL-PTX/DXR was prepared by the lipid film formation method. The release of PTX and DXR from liposomes was performed using a dialysis method. Studies of cytotoxicity, synergism, and cellular uptake were also carried out. Results: The encapsulation percentage of PTX and DXR was 74.1 ± 1.8 % and 89.6 ± 12.3%, respectively, and the mean diameter of the liposomes was 244.4 ± 28.1 nm. The vesicles remained stable for 30 days after their preparation. The drugs were simultaneously released from vesicles during 36 hours, maintaining the drugs combination in the previously established ratio. Cytotoxicity studies using 4T1 breast cancer cells showed lower inhibitory concentration 50% (IC50) value for LCFL-PTX/DXR treatment (0.27 ± 0.11 μm) compared to the values of free drugs treatment. In addition, the combination index (CI) assessed for treatment with LCFL-PTX/DXR was equal to 0.11 ± 0.04, showing strong synergism between the drugs. Cell uptake studies have confirmed that the molar ratio between PTX and DXR is maintained when the drugs are administered in liposomes. Conclusion: It was possible to obtain LCFL-PTX/DXR suitable for intravenous administration, capable of releasing the drugs in a fixed synergistic molar ratio in the tumor region.

Objective: A novel pH-sensitive superparamagnetic drug delivery system was developed based on quercetin loaded hyperbranched polyamidoamine-b-polyethylene glycol-folic acid-modified Fe3O4 nanoparticles (Fe3O4@PAMAM-b-PEG-FA). Methods: The nanoparticles exhibit excellent water dispersity with well-defined size distribution (around 51.8 nm) and strong magnetisability. In vitro release studies demonstrated that the quercetinloaded Fe3O4@PAMAM-b-PEG-FA nanoparticles are stable at normal physiologic conditions (pH 7.4 and 37°C) but sensitive to acidic conditions (pH 5.6 and 37°C), which led to the rapid release of the loaded drug. Results: Fluorescent microscopy results indicated that the Fe3O4@PAMAM-b-PEG-FA nanoparticles could be efficiently accumulated in tumor tissue compared with non-folate conjugated nanoparticles. Also, in comparison with free quercetin, the quercetin loaded Fe3O4@PAMAM-b-PEG-FA exerts higher cytotoxicity. Furthermore, this magnetic nanocarrier showed high MRI sensitivity, even in its lower iron content. Conclusion: The results indicated that the prepared nanoparticles are an effective chemotherapy and diagnosis system to inhibit proliferation and monitor the progression of tumor cells, respectively.

Objective: A novel natural polymer, Gum Ghatti (GG) was explored to develop a new polymeric system that will combine the biodegradable and biocompatible properties of GG and mechanical properties of poly vinyl alcohol (PVA) for drug delivery application. Methods: Smart pH sensitive, porous, glutaraldehyde (GA) crosslinked interpenetrating network (IPN) microspheres loaded with glipizide were developed by the emulsion crosslinking method. The drug entrapment efficiency was 92.85±1.5%. FTIR confirmed the formation of IPN structure. Drug release can be extended upto 7 hours by modulating the concentration of crosslinking agent. Swelling study and diffusion co-efficient (D) of water transport were performed in order to understand the phenomenon of water penetration through the microsphere. In vivo antidiabetic activity performed on alloxane induced diabetic rats indicated that in case of pure glipizide sudden reduction of elevated blood glucose was observed after 3 hours. Results: In case of rats treated with glipizide loaded IPN microparticles, the initial percentage reduction of blood glucose level was slow within the first 3 hours of administration, as compared to pure glipizide but after 6 hours 90% reduction was observed which confirmed sustained release nature of microspheres. Conclusion: Thus IPN microparticles were found suitable for sustained delivery of BCS class II drug glipizide.

Background: Nimodipine is a calcium channel blocker frequently used in critical care settings. It is mainly absorbed in the upper gastrointestinal tract. Accordingly, the development of gastroretentive formulation will be beneficial. The benefit would be maximized for critical care patients if the developed system was in liquid form to facilitate the administration through nasogastric tubing. Objective: Development of gastro-retentive liquid oral controlled release formulation of nimodipine through in situ gellation. Methods: Nimodipine dissolution was improved by solid dispersion (SD) using poloxamer 407. Sodium alginate solutions (1, 1.5 and 2%w/v) were loaded with the optimized SD microparticles. Carboxymethylcellulose was added to modulate the release and to augment mucoadhesion power. All in situ gelling alginate solutions were characterized regarding viscosity, gelling capacity and drug release. SD microparticles showed considerable improvement in nimodipine dissolution. Results: All alginate systems were pourable. Increasing alginate concentration increased the gelling capacity and reduced drug release rate. The addition of carboxymethylcellulose produced greater control over drug release rate. X-ray radiography showed successful stomach-retention over 8 hours in rabbits, which correlates with the controlled release pattern of the developed systems. Conclusion: The study provides the formulator with a range of gastroretentive controlled release formulations of nimodipine while maintaining the convenience of administration through nasogastric tubing with the potential for enhanced bioavailability.