Optimization on biodistribution and antitumor activity of tripterine using polymeric nanoparticles through RES saturation

Recent advances in drug delivery of celastrol for enhancing efficiency and reducing the toxicity

Celastrol is a quinone methyl triterpenoid monomeric ingredient extracted from the root of Tripterygium wilfordii. Celastrol shows potential pharmacological activities in various diseases, which include inflammatory, obesity, cancer, and bacterial diseases. However, the application prospect of celastrol is largely limited by its low bioavailability, poor water solubility, and undesired off-target cytotoxicity. To address these problems, a number of drug delivery methods and technologies have been reported to enhance the efficiency and reduce the toxicity of celastrol. We classified the current drug delivery technologies into two parts. The direct chemical modification includes nucleic acid aptamer-celastrol conjugate, nucleic acid aptamer-dendrimer-celastrol conjugate, and glucolipid-celastrol conjugate. The indirect modification includes dendrimers, polymers, albumins, and vesicular carriers. The current technologies can covalently bond or encapsulate celastrol, which improves its selectivity. Here, we present a review that focalizes the recent advances of drug delivery strategies in enhancing the efficiency and reducing the toxicity of celastrol.

Erythrocyte membrane-camouflaged DNA-functionalized upconversion nanoparticles for tumor-targeted chemotherapy and immunotherapy

A synergistic combination of treatment with immunogenic cell death (ICD) inducers and immunoadjuvants may be a practical way to boost the anticancer response and successfully induce an immune response. The use of HR@UCNPs/CpG-Apt/DOX, new biomimetic drug delivery nanoparticles generated to combat breast cancer, is reported here as a unique strategy to produce immunogenicity and boost cancer immunotherapy. HR@UCNPs/CpG-Apt/DOX (HR-UCAD) consists of two parts. The core is composed of an immunoadjuvant CpG (a toll-like receptor 9 agonist) fused with a dendritic cell-specific aptamer sequence (CpG-Apt) to decorate upconversion nanoparticles (UCNPs) with the successful intercalation of doxorubicin (DOX) into the consecutive base pairs of Apt-CpG to construct an immune nanodrug UCNPs@CpG-Apt/DOX. The targeting molecule hyaluronic acid (HA) was inserted into a red blood cell membrane (RBCm) to form the shell (HR). HR-UCAD possessed a strong capacity to specifically induce ICD. Following DOX-induced ICD of cancer cells, sufficient exposure to tumor antigens and UCNPs@CpG-Apt (UCA) activated the tumor-specific immune response and reversed the immunosuppressive tumor microenvironment. In addition, HR-UCAD has good biocompatibility and increases the active tumor-targeting effect. Furthermore, HR-UCAD exhibits excellent near-infrared upconversion luminescence emission at 804 nm under irradiation with a 980 nm laser, which has great potential in biomedical imaging. Thus, the RBCm-camouflaged drug delivery system is a promising targeted chemotherapy and immunotherapy nanocomplex that could be used for effective targeted breast cancer treatment.

Research and Application of Kupffer Cell Thresholds for BSA Nanoparticles

Over the past decade, the dose of nanoparticles given to solid tumors has remained at a median of 0.7% of the injected dose. Most nanoparticles are trapped in a mononuclear phagocyte system (MPS), of which 85% are Kupffer cells. In our study, threshold doses of bovine serum albumin (BSA) nanoparticles were investigated for the uptake of Kupffer cells in vitro and in vivo. The antitumor effect and safety of albumin-bound paclitaxel (ABP) were improved by using threshold doses of BSA nanoparticles. We found a threshold dose of 20,000 nanoparticles per macrophage uptake in vitro and a saturation dose of 0.3 trillion nanoparticles in tumor-bearing mice. In vivo efficacy and safety evaluations demonstrated that the threshold doses of blank BSA nanoparticles could significantly improve the efficacy and safety of ABP against tumors compared with ABP alone. In this study, the delivery efficiency of ABP was improved by using blank nanoparticles to saturate Kupffer cells, which provided a new approach to studying the Kupffer cell saturation threshold and thus a new scheme for improving the curative effect of ABP.

Recent progress in nanotechnology-based drug carriers for celastrol delivery

Celastrol (CLT) is an active ingredient that was initially discovered and extracted from the root of Tripterygium wilfordii. The potential pharmacological activities of CLT in cancer, obesity, and inflammatory, auto-immune, and neurodegenerative diseases have been demonstrated in recent years. However, CLT's clinical application is extremely restricted by its low solubility/permeability, poor bioavailability, and potential off-target toxicity. The advent of nanotechnology provides a solution to improve the oral bioavailability, therapeutic effects or tissue-targeting ability of CLT. This review focuses on the most recent advances, improvements, inventions, and updated literature of various nanocarrier systems for CLT.

Bioadhesive polymer/lipid hybrid nanoparticles as oral delivery system of raloxifene with enhancive intestinal retention and bioavailability

Raloxifene (RLX) is a second-generation selective estrogen receptor modulator used to treat osteoporosis in postmenopausal women. RLX fails to be developed into injectable dosage forms due to poor solubility. Although oral formulations are clinically available, the lower bioavailability (<2%) embarrasses the pharmaceutists. This work reported a bioadhesive nanosystem intended for oral delivery of RLX to enhance its oral bioavailability and address the formulation challenge. The bioadhesive nanosystem refers to polymer-lipid hybrid nanoparticles made up of Carbopol 940, glyceryl distearate, and TGPS. RLX was solidly encapsulated into bioadhesive nanoparticles (bNPs) through a nanoprecipitation technique along with synchronous desalting of RLX·HCl. The resultant RLX-loaded bNPs (RLX-bNPs) were characterized by particle size, ζ potential, morphology, and entrapment efficiency. The in vitro release and in vivo oral bioavailability of RLX-bNPs in rats were comparatively investigated with RLX-loaded common lipid nanoparticles (RLX-cNPs). The preferred formulation possesses a particle size of 150 nm around with a polydispersity index (PDI) of 0.282. RLX-bNPs exhibited slower drug release than RLX-cNPs owing to the presence of an adhesive layer. After oral administration, RLX-bNPs resulted in significant enhancement in the bioavailability of RLX, up to 556.9% relative to RLX suspensions, while it was merely 244.7% for RLX-cNPs. Cellular testing and ex vivo transport imaging demonstrated that bNPs were endowed with excellent intestinal epithelial affinity and absorbability. Our study affords an alternative option for designing a suitable oral delivery system specific to amphiphobic drugs like RLX·HCl.

Nanotechnology-Based Celastrol Formulations and Their Therapeutic Applications

Celastrol (also called tripterine) is a quinone methide triterpene isolated from the root extract of Tripterygium wilfordii (thunder god vine in traditional Chinese medicine). Over the past two decades, celastrol has gained wide attention as a potent anti-inflammatory, anti-autoimmune, anti-cancer, anti-oxidant, and neuroprotective agent. However, its clinical translation is very challenging due to its lower aqueous solubility, poor oral bioavailability, and high organ toxicity. To deal with these issues, various formulation strategies have been investigated to augment the overall celastrol efficacy in vivo by attempting to increase the bioavailability and/or reduce the toxicity. Among these, nanotechnology-based celastrol formulations are most widely explored by pharmaceutical scientists worldwide. Based on the survey of literature over the past 15 years, this mini-review is aimed at summarizing a multitude of celastrol nanoformulations that have been developed and tested for various therapeutic applications. In addition, the review highlights the unmet need in the clinical translation of celastrol nanoformulations and the path forward.

Celastrol: A Review of Useful Strategies Overcoming its Limitation in Anticancer Application

Celastrol, a natural bioactive ingredient derived from Tripterygium wilfordii Hook F, exhibits significant broad-spectrum anticancer activities for the treatment of a variety of cancers including liver cancer, breast cancer, prostate tumor, multiple myeloma, glioma, etc. However, the poor water stability, low bioavailability, narrow therapeutic window, and undesired side effects greatly limit its clinical application. To address this issue, some strategies were employed to improve the anticancer efficacy and reduce the side-effects of celastrol. The present review comprehensively focuses on the various challenges associated with the anticancer efficiency and drug delivery of celastrol, and the useful approaches including combination therapy, structural derivatives and nano/micro-systems development. The specific advantages for the use of celastrol mediated by these strategies are presented. Moreover, the challenges and future research directions are also discussed. Based on this review, it would provide a reference to develop a natural anticancer compound for cancer treatment.

Site-specific targeted drug delivery systems for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn's disease and ulcerative colitis and manifests as a complex and dysregulated immune response. To date, there is no cure for IBD; thus, lifelong administration of maintenance drugs is often necessary. Since conventional IBD treatment strategies do not target the sites of inflammation, only limited efficacy is observed with their use. Moreover, the possibility of severe side effects resulting from systemic drug redistribution is high when conventional drug treatments are used. Therefore, a straightforward disease-targeted drug delivery system is desirable. Based on the pathophysiological changes associated with IBD, novel site-specific targeted drug delivery strategies that deliver drugs directly to the inflammation sites can enhance drug accumulation and decrease side effects. This review summarizes novel inflammation targeted delivery systems in the management of IBD. It also discusses the challenges and new perspectives in this field.

Hyaluronic acid-functionalized bilosomes for targeted delivery of tripterine to inflamed area with enhancive therapy on arthritis

Arthritis treatment has been challenging because of low drug exposure to the articular cavity. This study was intended to develop hyaluronic acid (HA)-functionalized bilosomes for targeted delivery of tripterine (Tri), an antiphlogistic phytomedicine, to the inflamed joint via ligand-receptor interaction. Tri-loaded bilosomes (Tri-BLs) with cationic lipid (DOTAP) were prepared by a thin film hydration method followed by HA coating to form HA@Tri-BLs. HA@Tri-BLs were then characterized by particle size (PS), entrapment efficiency (EE), and structural morphology. The in vitro drug release, hemocompatibility test and cellular uptake were performed to examine the formulation performances of HA@Tri-BLs. The in vivo pharmacokinetics and antiarthritic efficacy were evaluated in arthritic models, respectively. The obtained HA@Tri-BLs possessed a PS of 118.5 nm around with an EE of 99.56%. HA@Tri-BLs exhibited excellent cellular uptake and targeted delivery efficiency for Tri, which resulted in elongation of circulatory residence time and enhancement of intra-arthritic bioavailability (799.9% relative to Tri solution). The in vivo antiarthritic efficacy of HA@Tri-BLs was also significantly superior to uncoated Tri-BLs that gave rise to obvious inflammation resolution. Our findings suggest that HA-functionalized bilosomes are a promising vehicle for articular delivery of antiphlogistic drugs to potentiate their efficacy.

Optimization of Preparation and Preclinical Pharmacokinetics of Celastrol-Encapsulated Silk Fibroin Nanoparticles in the Rat

Celastrol (CL), a bioactive compound isolated from Tripterygium wilfordii, has demonstrated bioactivities against a variety of diseases including cancer and obesity. However, its poor water solubility and rapid in vivo clearance limit its clinical applications. To overcome these limitations, nanotechnology has been employed to improve its pharmacokinetic properties. Nanoparticles made of biological materials offer minimal adverse effects while maintaining the efficacy of encapsulated therapeutics. Silk fibroin (SF) solution was prepared successfully by extraction from the cocoons of silkworms, and a final concentration of 2 mg/mL SF solution was used for the preparation of CL-loaded SF nanoparticles (CL-SFNP) by the desolvation method. A stirring speed of 750 rpm and storage time of 20 h at -20 °C resulted in optimized product yield. A high-performance liquid chromatography (HPLC) method was developed and validated for the analysis of CL in rat plasma in terms of selectivity, linearity, intra-/inter-day precision and accuracy, and recovery. No interference was observed in rat plasma. Linearity in the concentration range of 0.05-5 µg/mL was observed with R2 of 0.999. Precision and accuracy values were below the limit of acceptance criteria, i.e., 15% for quality control (QC) samples and 20% for lower limit of quantification (LLOQ) samples. Rats were given intravenous (IV) administration of 1 mg/kg of pure CL in PEG 300 solution or CL-SFNP. The pharmacokinetic profile was improved with CL-SFNP compared to pure CL. Pure CL resulted in a maximum concentration (Cmax) value of 0.17 µg mL-1 at 5 min following administration, whereas that for CL-SFNP was 0.87 µg mL-1 and the extrapolated initial concentrations (C0) were 0.25 and 1.09 µg mL-1, respectively, for pure CL and CL-SFNP. A 2.4-fold increase in total area under the curve (AUC0-inf) (µg h mL-1) was observed with CL-SFNP when compared with pure CL. CL-SFNP demonstrated longer mean residence time (MRT; 0.67 h) than pure CL (0.26 h). In conclusion, the preparation of CL-SFNP was optimized and the formulation demonstrated improved pharmacokinetic properties compared to CL in solution following IV administration.

Selenium-layered nanoparticles serving for oral delivery of phytomedicines with hypoglycemic activity to synergistically potentiate the antidiabetic effect

Diabetes mellitus (DM) remains a great challenge in treatment due to pathological complexity. It has been proven that phytomedicines and natural medicines have prominent antidiabetic effects. This work aimed to develop selenium-layered nanoparticles (SeNPs) for oral delivery of mulberry leaf and Pueraria Lobata extracts (MPE), a group of phytomedicines with significant hypoglycemic activities, to achieve a synergic antidiabetic effect. MPE-loaded SeNPs (MPE-SeNPs) were prepared through a solvent diffusion/in situ reduction technique and characterized by particle size, ζ potential, morphology, entrapment efficiency (EE) and drug loading (DL). The resulting MPE-SeNPs were 120 nm around in particle size with EE of 89.38% for rutin and 90.59% for puerarin, two marker components in MPE. MPE-SeNPs exhibited a slow drug release and good physiological stability in the simulated digestive fluid. After oral administration, MPE-SeNPs produced significant hypoglycemic effects both in the normal and diabetic rats. Ex vivo intestinal imaging and cellular examinations demonstrated that MPE-SeNPs were provided with outstanding intestinal permeability and transepithelial transport aptness. It was also revealed that MPE-SeNPs could alleviate the oxidative stress, improve the pancreatic function, and promote the glucose utilization by adipocytes. Our study provides new insight into the use of integrative nanomedicine containing phytomedicines and selenium for DM treatment.