Synergistic anti-tumor effects of bevacizumab and tumor targeted polymerized VEGF siRNA nanoparticles.

A variety of VEGF inhibitors have been reported to treat cancers by suppressing tumor angiogenesis. Bevacizumab, a monoclonal VEGF antibody, was the first FDA approved anti-angiogenic agent for cancer treatments. However, bevacizumab shows modest therapeutic efficiency and often cause resistant problem in significant populations of cancer patients. To solve these problem, we investigated the therapeutic efficacy of siRNA drugs targeting VEGF and combination of the RNAi drug with bevacizumab for cancer treatments. For efficient VEGF siRNA delivery, chemically polymerized siRNAs were complexed with thiolated-glycol chitosan (psi(VEGF)/tGC). The poly-VEGF siRNA and thiolated-glycol chitosan formed stable nanoparticles via electrostatic interaction and chemical crosslinking, and showed high accumulation in tumor tissues resulting in efficient gene silencing. Both VEGF siRNA nanoparticles and bevacizumab had efficient therapeutic effects in tumor xenograft mouse models. Interestingly, most pronounced therapeutic efficacy was observed when the two distinct VEGF inhibitors were treated in combination revealing synergistic effects. The results showed that the psi(VEGF)/tGC nanoparticle mediated knockdown of VEGF exerts anti-tumor effects and the combination treatments with bevacizumab can extend the treatments options to conventional bevacizumab treatments for cancer therapy.

Complete prevention of blood loss with self-sealing haemostatic needles.

Bleeding is largely unavoidable following syringe needle puncture of biological tissues and, while inconvenient, this typically causes little or no harm in healthy individuals. However, there are certain circumstances where syringe injections can have more significant side effects, such as uncontrolled bleeding in those with haemophilia, coagulopathy, or the transmission of infectious diseases through contaminated blood. Herein, we present a haemostatic hypodermic needle able to prevent bleeding following tissue puncture. The surface of the needle is coated with partially crosslinked catechol-functionalized chitosan that undergoes a solid-to-gel phase transition in situ to seal punctured tissues. Testing the capabilities of these haemostatic needles, we report complete prevention of blood loss following intravenous and intramuscular injections in animal models, and 100% survival in haemophiliac mice following syringe puncture of the jugular vein. Such self-sealing haemostatic needles and adhesive coatings may therefore help to prevent complications associated with bleeding in more clinical settings.

In vivo monitoring of angiogenesis in a mouse hindlimb ischemia model using fluorescent peptide-based probes.

Vascular endothelial growth factor receptor (VEGFR) and matrix metalloproteinase (MMP) are up-regulated in ischemic tissue and play pivotal roles in promoting angiogenesis. The purpose of the present study was to evaluate two fluorophore-conjugated peptide probes specific to VEGFR and MMP for dual-targeted in vivo monitoring of angiogenesis in a murine model of hindlimb ischemia. To this end, VEGFR-Probe and MMP-Probe were developed by conjugating distinct near-infrared fluorophores to VEGFR-binding and MMP substrate peptides, respectively. VEGFR-Probe exhibited specific binding to VEGFR on HUVECs, and self-quenched MMP-Probe produced strong fluorescence intensity in the presence of MMPs in vitro. Subsequently, VEGFR-Probe and MMP-Probe were successfully utilized for time course in vivo visualization of VEGFR or MMP, respectively. Simultaneous visualization provided information regarding the spatial distribution of these proteins, including areas of co-localization. This dual-targeted in vivo imaging approach will be useful for understanding the detailed mechanism of angiogenesis and for evaluating therapeutic angiogenesis.

Comparison of electrophysiological effects of calcium channel blockers on cardiac repolarization.

Dihydropyridine (DHP) calcium channel blockers (CCBs) have been widely used to treat of several cardiovascular diseases. An excessive shortening of action potential duration (APD) due to the reduction of Ca(2+) channel current (I Ca) might increase the risk of arrhythmia. In this study we investigated the electrophysiological effects of nicardipine (NIC), isradipine (ISR), and amlodipine (AML) on the cardiac APD in rabbit Purkinje fibers, voltage-gated K(+) channel currents (I Kr, I Ks) and voltage-gated Na(+) channel current (I Na). The concentration-dependent inhibition of Ca(2+) channel currents (I Ca) was examined in rat cardiomyocytes; these CCBs have similar potency on I Ca channel blocking with IC50 (the half-maximum inhibiting concentration) values of 0.142, 0.229, and 0.227 nM on NIC, ISR, and AML, respectively. However, ISR shortened both APD50 and APD90 already at 1 µM whereas NIC and AML shortened APD50 but not APD90 up to 30 µM. According to ion channel studies, NIC and AML concentration-dependently inhibited I Kr and I Ks while ISR had only partial inhibitory effects (<50% at 30 µM). Inhibition of I Na was similarly observed in the three CCBs. Since the I Kr and I Ks mainly contribute to cardiac repolarization, their inhibition by NIC and AML could compensate for the AP shortening effects due to the block of I Ca.

Cancer-targeted MDR-1 siRNA delivery using self-cross-linked glycol chitosan nanoparticles to overcome drug resistance.

P-glycoprotein (Pgp) mediated multi-drug resistance (MDR) is a major cause of failure in chemotherapy. In this study, small interfering RNA (siRNA) for Pgp down-regulation was delivered to tumors to overcome MDR in cancer. To achieve an efficient siRNA delivery in vivo, self-polymerized 5'-end thiol-modified siRNA (poly-siRNA) was incorporated in tumor targeting glycol chitosan nanoparticles. Pgp-targeted poly-siRNA (psi-Pgp) and thiolated glycol chitosan polymers (tGC) formed stable nanoparticles (psi-Pgp-tGC NPs), and the resulting nanoparticles protected siRNA molecules from enzymatic degradation. The psi-Pgp-tGC NPs could release functional siRNA molecules after cellular delivery, and they were able to facilitate siRNA delivery to Adriamycin-resistant breast cancer cells (MCF-7/ADR). After intravenous administration, the psi-Pgp-tGC NPs accumulated in MCF-7/ADR tumors and down-regulated P-gp expression to sensitize cancer cells. Consequently, chemo-siRNA combination therapy significantly inhibited tumor growth without systemic toxicity. These psi-Pgp-tGC NPs showed great potential as a supplementary therapeutic agent for drug-resistant cancer.

Wide spectrum of inhibitory effects of sertraline on cardiac ion channels.

Sertraline is a commonly used antidepressant of the selective serotonin reuptake inhibitors (SSRIs) class. In these experiments, we have used the whole cell patch clamp technique to examine the effects of sertraline on the major cardiac ion channels expressed in HEK293 cells and the native voltage-gated Ca(2+) channels in rat ventricular myocytes. According to the results, sertraline is a potent blocker of cardiac K(+) channels, such as hERG, I(Ks) and I(K1). The rank order of inhibitory potency was hERG >I(K1)> I(Ks) with IC(50) values of 0.7, 10.5, and 15.2 µM, respectively. In addition to K(+) channels, sertraline also inhibited I(Na) and I(Ca), and the IC(50) values are 6.1 and 2.6 µM, respectively. Modification of these ion channels by sertraline could induce changes of the cardiac action potential duration and QT interval, and might result in cardiac arrhythmia.

Electrophysiological effects of the anti-cancer drug lapatinib on cardiac repolarization.

Lapatinib is one of several tyrosine kinase inhibitors used against solid tumour cancers such as breast and lung cancer. Although lapatinib is associated with a risk of QT prolongation, the effects of the drug on cellular cardiac electrical properties and on action potential duration (APD) have not been studied. To evaluate the potential effects of lapatinib on cardiac repolarization, we investigated its electrophysiological effects using a whole-cell patch-clamp technique in transiently transfected HEK293 cells expressing human ether-à-go-go (hERG; to examine the rapidly activating delayed rectifier K(+) current, I(Kr)), KCNQ1/KCNE1 (to examine the slowly activating delayed rectifier K(+) current, I(Ks)), KCNJ2 (to examine the inwardly rectifying K(+) current, I(K1)), or SCN5A (to examine the inward Na(+) current, I(Na)) and in rat cardiac myocytes (to examine the inward Ca(2+) current, I(Ca)). We also examined its effects on the APD at 90% (APD(90)) in isolated rabbit Purkinje fibres. In ion channel studies, lapatinib inhibited the hERG current in a concentration-dependent manner, with a half-maximum inhibition concentration (IC(50)) of 0.8 +/- 0.09 microm. In contrast, at concentrations up to 3 microm, lapatinib did not significantly reduce the I(Na), I(K1) or I(Ca) amplitudes; at 3 microm, it did slightly inhibit the I(Ks) amplitude (by 19.4 +/- 4.7%; p < 0.05). At 5 microm, lapatinib induced prolongation of APD(90) by 16.1% (p < 0.05). These results suggest that the APD(90)-prolonging effect of lapatinib on rabbit Purkinje fibres is primarily a result of inhibition of the hERG current and I(Ks), but not I(Na), I(K1) or I(Ca).