HPLC analysis and extraction method of SN-38 in brain tumor model after injected by polymeric drug delivery system

Antibacterial and biocompatibility studies of triple antibiotics-impregnated external ventricular drainage: In vitro and in vivo evaluation

Hydrocephalus is a neurological disease caused by an unusually high level of cerebrospinal fluid (CSF), which can be relieved by external ventricular drainage (EVD) insertion. However, the infection can lead to complications during the use of EVD. In this study, EVD was impregnated with three synergistic antibiotics, including rifampicin, clindamycin, and trimethoprim, to improve the antibacterial property. The impregnated drainage was studied for its characteristics in vitro and in vivo. Drug loading determination revealed that rifampicin had the highest concentration in the tube, followed by clindamycin and trimethoprim, respectively. In vitro cytotoxicity and hemolytic studies showed no toxic effects from antibiotics-impregnated EVD on fibroblast and red blood cells. For antibacterial testing, the impregnated EVD exhibited antibacterial activity against Staphylococcus aureus MRSA and Staphylococcus epidermidis up to 14 and 90 days, respectively. Moreover, biocompatibility and drug release into the bloodstream and surrounding tissues were investigated by implantation in rabbits for 30 days. Histology and morphology results showed that fibroblast cells began to adhere to the drainage surface and inflammatory cell numbers were noticeably small after the long-term implantation. In addition, there was no drug leakage to the bloodstream and surrounding tissues. Hence, this impregnated EVD can potentially be used for antibacterial application.

Targeted Delivery of DNA Topoisomerase Inhibitor SN38 to Intracranial Tumors of Glioblastoma Using Sub-5 Ultrafine Iron Oxide Nanoparticles

Effectively delivering therapeutics for treating brain tumors is hindered by the physical and biological barriers in the brain. Even with the compromised blood-brain barrier and highly angiogenic blood-tumor barrier seen in glioblastoma (GBM), most drugs, including nanomaterial-based formulations, hardly reach intracranial tumors. This work investigates sub-5 nm ultrafine iron oxide nanoparticles (uIONP) with 3.5 nm core diameter as a carrier for delivering DNA topoisomerase inhibitor 7-ethyl-10-hydroxyl camptothecin (SN38) to treat GBM. Given a higher surface-to-volume ratio, uIONP shows one- or three-folds higher SN38 loading efficiency (48.3 ± 6.1%, mg/mg Fe) than those with core sizes of 10 or 20 nm. SN38 encapsulated in the coating polymer exhibits pH sensitive release with <10% over 48 h at pH 7.4, but 86% at pH 5, thus being protected from converting to inactive glucuronide by UDP-glucuronosyltransferase 1A1. Conjugating α_v β₃ -integrin-targeted cyclo(Arg-Gly-Asp-D-Phe-Cys) (RGD) as ligands, RGD-uIONP/SN38 demonstrates targeted cytotoxicity to α_v β₃ -integrin-overexpressed U87MG GBM cells with a half-maximal inhibitory concentration (IC₅₀ ) of 30.9 ± 2.2 nm. The efficacy study using an orthotopic mouse model of GBM reveals tumor-specific delivery of 11.5% injected RGD-uIONP/SN38 (10 mg Fe kg^-1 ), significantly prolonging the survival in mice by 41%, comparing to those treated with SN38 alone (p < 0.001).

Mechanism and optimization of supramolecular complexation-enhanced fluorescence spectroscopy for the determination of SN-38 in plasma and cells

Quantitative detection of two different forms of SN-38 in biological samples is, currently, cumbersome and difficult. A revisit to the mechanism of supramolecular complexation-enhanced fluorescence spectroscopy helps to optimize the determination of SN-38 in plasma and the cellular pharmacokinetics in A549 cells based on the supramolecular complexation. Firstly, the inclusion mechanism dominated by thermodynamic constants was determined by measuring kinetic/thermodynamic parameters (k_on , k_off , ΔG, ΔH, ΔS). On this basis, the best effect of fluorescence sensitization was optimized through screening the interaction conditions (cyclodextrin species and concentrations, drug levels, temperature, pH of the buffer, and reaction time). Furthermore, the proportional relationship between the concentration of the inclusion complex and the fluorescence intensity was confirmed. Finally, a highly sensitive, selective spectrofluorimetric method was established and validated for quantitative analysis of the lactone and carboxylate molecular states of SN-38 plasma levels in rats and cell membrane transfer kinetics in A549 cell lines. The limits of detection for the lactone and carboxylate forms in plasma were found to be 0.44 ng·ml^-1 and 0.28 ng·ml^-1 , respectively. Precision and accuracy met the requirements of biological samples analysis. The proposed detection method provided a reference for elucidating the biodistribution of SN-38.

Injectable SN-38-embedded Polymeric Microparticles Promote Antitumor Efficacy against Malignant Glioma in an Animal Model

Malignant glioma (MG) is extremely aggressive and highly resistant to chemotherapeutic agents. Using electrospraying, the potent chemotherapeutic agent 7-ethyl-10-hydroxycamptothecia (SN-38) was embedded into 50:50 biodegradable poly[(d,l)-lactide-co-glycolide] (PLGA) microparticles (SMPs). The SMPs were stereotactically injected into the brain parenchyma of healthy rats and intratumorally injected into F98 glioma-bearing rats for estimating the pharmacodynamics and therapeutic efficacy. SN-38 was rapidly released after injection and its local (brain tissue) concentration remained much higher than that in the blood for more than 8 weeks. Glioma-bearing rats were divided into three groups—group A (n = 13; stereotactically injected pure PLGA microparticles), group B (n = 12; stereotactically injected Gliadel wafer and oral temozolomide), and group C (n = 13; stereotactic and intratumoral introduction of SMPs). The SMPs exhibited significant therapeutic efficacy, with prolonged survival, retarded tumor growth, and attenuated malignancy. The experimental results demonstrated that SMPs provide an effective and potential strategy for the treatment of MG.

Reduction the Initial-Burst Release of Doxorubicin from Polymeric Depot as a Local Drug Delivery System for Cancer Treatment

A sustained release that can be controllable is an ultimate goal for the delivery of drugs in drug delivery systems including in situ depots. However, one of the major persistent problems in the controlled release delivery system development is the initial burst release of the loaded drug which can minimize the effectiveness of the system. Our primary research objective was to reduce the initial burst release of Doxorubicin (Dox) encapsulated in polymeric depots by incorporating deprotonated Dox into the depots. The drug release profile and cytotoxicity effect of various concentrations of hydrophobic Dox-loaded depots were studied. In the first 24 hours after forming the depots, the release of Dox reached 82.9 ± 0.6% in Dox·HCl depots. Interestingly, the initial burst releases of 5, 10 and 15% wt/wt hydrophobic Dox-loaded PLEC depots were reduced to 48.5 ± 10.0, 29.2 ± 7.8 and 18.9 ± 0.9%, respectively. Moreover, 15% hydrophobic Dox-loaded PLEC depots maintained their stability up to 14 days and their in vitro cytotoxicity ability against human hepatocellular carcinoma cell line (HepG2). Taken together, this study suggested that the presence of hydrophobic Dox in Dox-loaded PLEC depots reduced the initial burst release phenomenon of the drug and the depots still maintained their function as a local drug delivery system.

Development of self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system for liver cancer chemotherapy

The objective of this work was to develop self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system for liver cancer chemotherapy and studied the release profiles of doxorubicin (Dox) from different depot formulations. Tri-block copolymers of poly(ε-caprolactone), poly(D,L-lactide) and poly(ethylene glycol) named PLECs were successfully used as a biodegradable material to encapsulate Dox as the injectable local drug delivery system. Depot formation and encapsulation efficiency of these depots were evaluated. Results show that depots could be formed and encapsulate Dox with high drug loading content. For the release study, drug loading content (10, 15 and 20% w/w) and polymer concentration (25, 30, and 35% w/v) were varied. It could be observed that the burst release occurred within 1-2 days and this burst release could be reduced by physical mixing of hydroxypropyl-beta-cyclodextrin (HP-β-CD) into the depot system. The degradation at the surface and cross-section of the depots were examined by Scanning Electron Microscope (SEM). In addition, cytotoxicity of Dox-loaded depots and blank depots were tested against human liver cancer cell lines (HepG2). Dox released from depots significantly exhibited potent cytotoxic effect against HepG2 cell line compared to that of blank depots. Results from this study reveals an important insight in the development of injectable drug delivery system for liver cancer chemotherapy. Schematic diagram of self-forming doxorubicin-loaded polymeric depots as an injectable drug delivery system and in vitro characterizations. (a) Dox-loaded PLEC depots could be formed with more than 90% of sustained-release Dox at 25% polymer concentration and 20% Dox-loading content. The burst release occurred within 1-2 days and could be reduced by physical mixing of hydroxypropyl-beta-cyclodextrin (HP-β-CD) into the depot system. (b) Dox released from depots significantly exhibited potent cytotoxic effect against human liver cancer cell lines (HepG2 cell line) compared to that of blank depots.

Paclitaxel-loaded polymeric depots as injectable drug delivery system for cancer chemotherapy of hepatocellular carcinoma

In this work, paclitaxel-encapsulated polymeric depots were prepared and characterized as drug delivery system for cancer chemotherapy against hepatocellular carcinoma. Effects of different parameters, including drug-loading content, polymer concentration and depot weight on depot formation, percentage of sustained-release taxol and drug release profile were evaluated. Paclitaxel-loaded depots were successfully formed at the polymer concentration above 25% w/v. For all formulations, paclitaxel could be encapsulated with very high percentage of sustained-release taxol (>90%). The release rate of paclitaxel from depots could be controlled by the amount of drug-loading content, polymer concentration and depot weight. Cytotoxicity against liver cancer cell line, HepG2, was evaluated by medium extraction method. Paclitaxel releasing from depots showed cytotoxic effect against HepG2 at different incubation times, whereas blank depots exhibited no cytotoxicity.

Antitumor efficacy and intratumoral distribution of SN-38 from polymeric depots in brain tumor model

We investigate antitumor efficacy and 2D and 3D intratumoral distribution of 7-ethyl-10-hydroxycamptothecin (SN-38) from polymeric depots inside U-87MG xenograft tumor model in nude mice. Results showed that polymeric depots could be used to administer and controlled release of a large amount of SN-38 directly to the brain tumor model. SN-38 released from depots suppressed tumor growth, where the extent of suppression greatly depended on doses and the number of depot injections. Tumor suppression of SN-38 from depots was three-fold higher in animals which received double injections of depots at high dose (9.7 mg of SN-38) compared to single injection (2.2 mg). H&E staining of tumor sections showed that the area of tumor cell death/survival of the former group was two-fold higher than those of the latter group. Fluorescence imaging based on self-fluorescent property of SN-38 was used to evaluate the intratumoral distribution of this drug compared to histological results. The linear correlation between fluorescence intensity and the amount of SN-38 allowed quantitative determination of SN-38 in tumor tissues. Results clearly showed direct correlation between the amount of SN-38 in tumor sections and cancer cell death. Moreover, 3D reconstruction representing the distribution of SN-38 in tumors was obtained. Results from this study suggest the rationale for intratumoral drug administration and release of drugs inside tumor, which is necessary to design drug delivery systems with efficient antitumor activity.