Hsiang-Fa Liang’s research while affiliated with Industrial Technology Research Institute and other places

The therapeutic effectiveness of chemotherapy is optimal only when tumor cells are subjected to a maximum drug exposure. To increase the intratumoral drug concentration and thus the efficacy of chemotherapy, a thermoresponsive bubble-generating liposomal system is proposed for triggering localized extracellular drug delivery. The key component of this liposomal formulation is the encapsulated ammonium bicarbonate (ABC), which is used to create the transmembrane gradient needed for a highly efficient encapsulation of doxorubicin (DOX). At an elevated temperature (42 °C), decomposition of ABC generates CO2 bubbles, creating permeable defects in the lipid bilayer that rapidly release DOX and instantly increase the drug concentration locally. Because the generated CO2 bubbles are hyperechogenic, they also enhance ultrasound imaging. Consequently, this new liposomal system encapsulated with ABC may also provide an ability to monitor of a temperature-controlled drug delivery process.

Bubbling over: After endocytosis and intracellular trafficking to lysosomes, liposomes containing ammonium bicarbonate can be thermally triggered to generate CO(2) bubbles. These bubbles grow rapidly and collapse violently to induce transient cavitation, a process that can disrupt the lysosomal membrane and release lysosomal proteases, thus leading to cell necrosis.

Blasen, die Membranen brechen: Nach Endozytose und intrazellulärer Überführung in Lysosome können Ammoniumbicarbonat enthaltende Liposome thermisch induziert CO2‐Blasen freisetzen (siehe Schema), die schnell wachsen und in sich zusammenstürzen. Dieser Prozess, bei dem vorübergehend Hohlräume erzeugt werden, kann die Lysosomenmembran schädigen, was zur Freisetzung lysosomaler Proteasen und somit zur Zellnekrose führt.

The clinical application of chemotherapy to brain tumors has been severely limited because the blood-brain barrier (BBB) often prevents therapeutic levels from being achieved. Here we show that pulsed HIFU and human atherosclerotic plaque-specific peptide-1 (AP-1)-conjugated liposomes containing doxorubicin (AP-1 Lipo-Dox) act synergistically in an experimental brain tumor model. We developed an intracranial brain-tumor model in NOD-scid mice using human brain glioblastoma multiforme (GBM) 8401 cells. Pulsed HIFU was used to transcranially disrupt the BBB in these mouse brains by delivering ultrasound waves in the presence of microbubbles. Prior to each sonication, AP-1 Lipo-Dox or unconjugated Lipo-Dox was administered intravenously, and the concentration in the brains was quantified by fluorometer. Compared to control animals treated with injections of AP-1 Lipo-Dox or unconjugated Lipo-Dox, animals receiving the drug followed by pulsed HIFU exhibited enhanced accumulation of the drug in tumor cells. Drug injection with sonication increased the tumor-to-normal brain doxorubicin ratio of the target tumors by about twofold compared with the control tumors. Moreover, the tumor-to-normal brain ratio was highest after the injection of AP-1 Lipo-Dox with sonication. Combining sonication with AP-1 Lipo-Dox also significantly inhibited tumor growth compared with chemotherapy alone. There was a modest but significant increase in the median survival time in mice treated with AP-1 Lipo-Dox followed by pulsed HIFU, compared to those treated with AP-1 Lipo-Dox without sonication. The use of AP-1-conjugated liposomes carrying cytotoxic agents followed by pulsed HIFU represents a feasible approach for enhanced targeted drug delivery in brain tumor therapies.

Background High-dose tissue-specific delivery of therapeutic agents would be a valuable clinical strategy. We have previously shown that repeated transcranial focused ultrasound is able to increase the delivery of Evans blue significantly into brain tissue. The present study shows that repeated pulsed high-intensity focused ultrasound (HIFU) can be used to deliver high-dose atherosclerotic plaque-specific peptide-1 (AP-1)-conjugated liposomes selectively to brain tumors. Methods Firefly luciferase (Fluc)-labeled human GBM8401 glioma cells were implanted into NOD-scid mice. AP-1-conjugated liposomal doxorubicin or liposomal doxorubicin alone was administered followed by pulsed HIFU and the doxorubicin concentration in the treated brains quantified by fluorometer. Growth of the labeled glioma cells was monitored through noninvasive bioluminescence imaging and finally the brain tissue was histologically examined after sacrifice. Results Compared with the control group, the animals treated with 5 mg/kg injections of AP-1 liposomal doxorubicin or untargeted liposomal doxorubicin followed by repeated pulsed HIFU not only showed significantly enhanced accumulation of drug at the sonicated tumor site but also a significantly elevated tumor-to-normal brain drug ratio (P < 0.001). Combining repeated pulsed HIFU with AP-1 liposomal doxorubicin or untargeted liposomal doxorubicin has similar antitumor effects. Conclusion This study demonstrates that targeted or untargeted liposomal doxorubicin, followed by repeated pulsed HIFU, is a promising high-dose chemotherapy method that allows the desired brain tumor region to be targeted specifically.

A liposome formulation for paclitaxel was developed in this study. The liposomes, composed of naturally unsaturated and hydrogenated phosphatidylcholines, with significant phase transition temperature difference, were prepared and characterized. The liposomes exhibited a high content of paclitaxel, which was incorporated within the segregated microdomains coexisting on phospholipid bilayer of liposomes. As much as 15% paclitaxel to phospholipid molar ratio were attained without precipitates observed during preparation. In addition, the liposomes remained stable in liquid form at 4°C for at least 6 months. The special composition of liposomal membrane which could reduce paclitaxel aggregation could account for such a capacity and stability. The cytotoxicity of prepared paclitaxel liposomes on the colon cancer C-26 cell culture was comparable to Taxol. Acute toxicity test revealed that LD(50) for intravenous bolus injection in mice exceeded by 40 mg/kg. In antitumor efficacy study, the prepared liposomal paclitaxel demonstrated the increase in the efficacy against human cancer in animal model. Taken together, the novel formulated liposomes can incorporate high content of paclitaxel, remaining stable for long-term storage. These animal data also demonstrate that the liposomal paclitaxel is promising for further clinical use.

A natural compound, aglycone geniposidic acid (aGSA), originated from the fruits of Gardenia jasminoides ELLIS was used for the fixation of collagenous tissues. The presumed crosslinking reaction mechanism of collagenous tissues with aGSA was inferred by reacting aGSA with a bifunctional amine, 1,6-hexanediamine, using a series of (1)H NMR, FT-IR, and UV/Vis spectra analyses. aGSA reacted with 1,6-hexanediamine by a nucleophilic attack on the olefinic carbon atom at C-2 of deoxyloganin aglycone, followed by opening the dihydropyran ring to form heterocyclic amine compounds. It is inferred that aGSA may form intramolecular and intermolecular crosslinks with a heterocyclic structure within collagen fibers in tissues. The degrees of tissue fixation by aGSA at different pH values were investigated by examining the fixation indices and denaturation temperatures of test samples. It was found that the fixation indices and denaturation temperatures of test samples fixed at neutral or basic pH (pH 7.4 or pH 8.5) were significantly greater than at acidic pH (pH 4.0). The results obtained in this study may be used to elucidate the crosslinking mechanism and optimize the fixation process for developing bioprostheses fixed by aGSA.

Pluronic block copolymers (PBCs) have been shown to reverse multidrug resistance (MDR) by inhibiting the P-glycoprotein (P-gp) pump in cancer cells. One of the problems encountered with the use of PBCs is that the micelles disassociate at low concentrations. The study focused on the stabilization of PBC L121 micelles by the formation of crosslinks within their outer shells. To form crosslinks, the two terminal alcohols on L121 were first chemically converted into aldehydes (L121-CHO) using the Dess-Martin periodinane. Diamine compounds were then used to bridge the converted aldehyde termini on L121-CHO via conjugated Schiff bases. After crosslinking, the morphology of the L121 micelles remained spherical in shape and the mean particle sizes of the micelles before and after crosslinking were comparable (100nm). After exposure of MDR KBv cells to free rhodamine-123 (R123), the accumulation of R123 in cells was limited due to the function of P-gp. In contrast, crosslinking of L121 micelles within their outer shells significantly reduced their critical micelle concentration and greatly enhanced their stability, while maintaining their ability to inhibit P-gp function in resistant cells. The results indicated that the L121 micelles with shell crosslinks may be useful as a drug delivery vehicle for cancer chemotherapy.

Nanoparticles (NPs) composed of chitosan (CS) and poly(gamma-glutamic acid) (gamma-PGA) were prepared by a simple ionic-gelation method for oral insulin delivery. Fourier transform infrared (FT-IR) spectra indicated that CS and gamma-PGA were ionized at pH 2.5-6.6, while X-ray diffractograms demonstrated that the crystal structure of CS was disrupted after it was combined with gamma-PGA. The diameters of the prepared NPs were in the range of 110-150 nm with a negative or positive surface charge, depending on the relative concentrations of CS to gamma-PGA used. The NPs with a positive surface charge (or shelled with CS) could transiently open the tight junctions between Caco-2 cells and thus increased the paracellular permeability. After loading of insulin, the NPs remained spherical and the insulin release profiles were significantly affected by their stability in distinct pH environments. The in vivo results clearly indicated that the insulin-loaded NPs could effectively reduce the blood glucose level in a diabetic rat model.