In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-cross-linked chitosan microspheres in colorectal cancer therapy in rats.

PURPOSE: Microspheres of chitosan (CS) cross-linked with polyethylene glycol (PEG) were prepared by emulsion-cross-linking followed by the solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology, and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell-lines. METHODS: In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy. RESULTS: The 5-FU immediate release (IR) formulations suspended in SCMC produced an immediate cytotoxic effect, whereas microspheres inhibited proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC50) values for both standard plain 5-FU and 5-FU-loaded microspheres were respectively 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC50 value required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared with 5-FU loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia, and thrombocytopenia were observed in animals for the standard 5-FU formulation. CONCLUSION: The PEG cross-linked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-crosslinked chitosan microspheres in colorectal cancer therapy in rats.

PURPOSE: Microspheres of chitosan (CS) crosslinked with polyethylene glycol (PEG) were prepared by emulsion crosslinking followed by solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell lines. METHODS: In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy. RESULTS: The 5-FU immediate release (IR) formulations suspended in sodium carboxymethyl cellulose (SCMC) produced an immediate cytotoxic effect, whereas microspheres inhibited the proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC50) values for both standard plain 5-FU and 5-FU-loaded microspheres were, respectively, 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC50 required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's Stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared to 5-FU-loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia and thrombocytopenia were observed in animals for the standard 5-FU formulation. CONCLUSION: The PEG-crosslinked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

Oral insulin delivery using deoxycholic acid conjugated PEGylated polyhydroxybutyrate co-polymeric nanoparticles.

AIM: To develop insulin loaded deoxycholic acid conjugated PEGylated polyhydroxybutyrate co-polymeric nanoparticles and carry out in vitro and in vivo testing of enteric coated granules comprising these nanoparticles. MATERIALS & METHODS: Insulin loaded nanoparticles were prepared and characterized in vitro. Cellular uptake was studied using hyperspectral and live cell confocal microscopy. Enteric coated granules of nanoparticles were fed orally to diabetic rats and the pharmacokinetic and pharmacodynamic parameters were evaluated. RESULTS: Ultra small (˜10 nm) nanoparticles with polydispersity index of 0.299 were obtained. The enteric coated granules showed a negligible insulin release in acidic pH, but released insulin in alkaline environment. High cellular uptake was observed and nanoparticles were able to maintain the blood glucose levels up to 24 h. CONCLUSION: These enteric-coated nanoparticle granules sustained the release of insulin and showed enhanced insulin bioavailability. Hence, these may serve as a platform device for oral insulin delivery with extended release.

Cytotoxicity and antitumour activity of 5-fluorouracil-loaded polyhydroxybutyrate and cellulose acetate phthalate blend microspheres.

Pharmacokinetics, biodistribution and antitumour activity of 5-fluorouracil (5-FU)-loaded polyhydroxybutyrate (PHB) and cellulose acetate phthalate (CAP) blend microspheres were investigated in chemically induced colorectal cancer in albino male Wistar rats and compared with pristine 5-FU given as a suspension. The microspheres were characterised for particle size, encapsulation efficiency, in vitro release and in vitro cytotoxicity on human HT-29 colon cancer cell line. Spherical particles with a mean size of 44 ± 11 µm were obtained that showed sustained release of 5-FU. A high concentration of 5-FU was achieved in colonic tissues and significant reduction in tumour volume and multiplicity were observed in animals treated with 5-FU-loaded microspheres. The decreased levels of plasma albumin, creatinine, leucocytopenia and thrombocytopenia were observed in animals for 5-FU microspheres compared to the standard 5-FU formulation. The results suggest the extended release of 5-FU from the PHB-CAP blend microspheres in colonic region to enhance the antitumour efficacy.

Cyclodextrin-based siRNA delivery nanocarriers: a state-of-the-art review.

INTRODUCTION: The discovery of synthetic small interfering RNA (siRNA) has led to a surge of interest in harnessing RNA interference (RNAi) technology for biomedical applications and drug development. Even though siRNA can be a powerful therapeutic drug, its delivery remains a major challenge, due to the difficulty in its cellular uptake. Naked siRNA has a biological half-life of less than an hour in human plasma. To increase the lifetime and improve its therapeutic efficacy, non-viral vectors have been developed. As a natural evolution, cyclodextrins (CDs), which are natural cyclic oligosaccharides, have recently been applied as delivery vehicles for siRNA, and this in turn, has led to a surge of interest in this area. AREAS COVERED: This review discusses the recent advances made in the design of delivery strategies for siRNA, focusing on CD-based delivery vectors, because these have demonstrated clinical success. The methods of preparation of CD-based vectors, their characterization, transfection efficiencies, cellular toxicity, preclinical and clinical trials are also addressed, as well as future therapeutic applications. EXPERT OPINION: siRNA-mediated RNAi therapeutics is beginning to transform healthcare, particularly, for the treatment of solid tumors. For example, CALAA01, a targeted, self-assembling nanoparticle system based on CD complexed with siRNA has been effective in phase I clinical trials. Although siRNA therapeutics suffers from problems related to off-target effects and non-specific gene silencing, these problems can be overcome by reducing the nanoparticle size, improving the targeting efficiency and by modifying the primary sequence of the siRNA.

A novel method for the preparation of nanoaggregates of methoxy polyethyleneglycol linked chitosan.

In the study, methoxy polyethyleneglycol (MPEG) linked chitosan (PLC) with a different degrees of substitution were prepared using a novel yet simple method in the presence of formaldehyde in a solvent of formic acid and dimethylsulfoxide (DMSO). The obtained PLC was verified by the Fourier transformed infrared (FT-IR) and carbon nuclear magnetic resonance (13C-NMR) spectroscopy and by the gel permeation chromatography (GPC). The aqueous solubility of chitosan increased after chemically linking with MPEG and was found to depend on its degree of substitution. With a proper degree of substitution of MPEG on chitosan, PLC may undergo inter- and/or intra-molecular entanglements to produce nanoaggregates. The critical aggregation concentration (CAC) of PLC was determined by the fluorescence emission spectra of pyrene and was found to be 0.003 mg/ml. Measurements of the size distribution and zeta potential of the prepared nanoaggregates were carried out using a Zetasizer. The results suggested that as the degree of MPEG substitution increased, the size and polydispersity index of the prepared nanoaggregates decreased. The prepared nanoaggregates showed a pH-sensitive property and thus may be suitable for the development of drug delivery devices for tumors.

Paclitaxel-loaded poly(gamma-glutamic acid)-poly(lactide) nanoparticles as a targeted drug delivery system for the treatment of liver cancer.

The study was to develop paclitaxel-loaded formulations using a novel type of self-assembled nanoparticles (P/NPs) composed of block copolymers synthesized by poly(gamma-glutamic acid) and poly(lactide). For the potential of targeting liver cancer cells, galactosamine was conjugated on the prepared nanoparticles (Gal-P/NPs). In the in vitro studies, it was found that both the P/NPs and the Gal-P/NPs had a similar release profile of paclitaxel. The activity in inhibiting the growth of HepG2 cells by the Gal-P/NPs was comparable to that of a clinically available paclitaxel formulation (Phyxol), while the P/NPs displayed a significantly less activity (p<0.05). The biodistribution and anti-tumor efficacy of the prepared nanoparticles were studied in hepatoma-tumor-bearing nude mice. It was found that the groups injected with Phyxol, the P/NPs or the Gal-P/NPs significantly delayed the tumor growth as compared to the control group injected with PBS (p<0.05). Among all studied groups, the group injected with the Gal-P/NPs appeared to have the most significant efficacy in the reduction of the size of the tumor. This is because a large number of the Gal-P/NPs were observed at the tumor site, and subsequently released their encapsulated paclitaxel to inhibit the growth of the tumor. The aforementioned results indicated that the Gal-P/NPs prepared in the study had a specific interaction with the hepatoma tumor induced in nude mice via ligand-receptor recognition. Therefore, the prepared Gal-P/NPs may be used as a potential drug delivery system for the targeted delivery to liver cancers.

Targeted nanoparticles for drug delivery through the blood-brain barrier for Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia among the elderly, affecting 5% of Americans over age 65, and 20% over age 80. An excess of senile plaques (beta-amyloid protein) and neurofibrillary tangles (tau protein), ventricular enlargement, and cortical atrophy characterizes it. Unfortunately, targeted drug delivery to the central nervous system (CNS), for the therapeutic advancement of neurodegenerative disorders such as Alzheimer's, is complicated by restrictive mechanisms imposed at the blood-brain barrier (BBB). Opsonization by plasma proteins in the systemic circulation is an additional impediment to cerebral drug delivery. This review gives an account of the BBB and discusses the literature on biodegradable polymeric nanoparticles (NPs) with appropriate surface modifications that can deliver drugs of interest beyond the BBB for diagnostic and therapeutic applications in neurological disorders, such as AD. The physicochemical properties of the NPs at different surfactant concentrations, stabilizers, and amyloid-affinity agents could influence the transport mechanism.

A novel method for the synthesis of the PEG-crosslinked chitosan with a pH-independent swelling behavior.

In this study, a simple method was developed to crosslink chitosan using poly(ethylene glycol) (PEG) with different molecular weights. Crosslinking of chitosan was confirmed by various spectral analyses. The differential scanning calorimetric (DSC) study indicated that the rigid crystalline structure of chitosan was decreased after crosslinking with PEG. The PEG-crosslinked chitosan (PEG-Ch) showed a pH-independent swelling behavior: swelled in both the simulated stomach (pH 1.1) and intestinal (pH 7.4) solutions. The swelling ratio of PEG-Ch increased significantly with a higher molecular weight of PEG used. In contrast, chitosan dissolved completely in a simulated stomach solution and showed a comparatively less swelling in a simulated intestinal solution. Thus, the prepared PEG-Ch could be a better biomaterial than chitosan in the development of orally sustained drug-delivery devices.

Anti-microbial activity and film characterization of thiazolidinone derivatives of chitosan.

Thiazolidinone derivatives (TDCs) were prepared by converting chitosan into chitosan's Schiff's bases (CSBs), followed by treatment with mercaptoacetic acid. Both CSBs and TDCs were tested for antimicrobial activity against four different bacteria. All TDCs showed comparatively better anti-microbial activity without much affecting basic physical properties of chitosan such as film-forming capacity, tensile strength, etc. This indicates that chitosan derivatives with a thiazolidinone moiety might be a better material for wound dressing.