Ultrasound-enhanced drug delivery in prostate cancer xenografts by nanoparticles stabilizing microbubbles

Nanoparticle delivery to the brain--By focused ultrasound and self-assembled nanoparticle-stabilized microbubbles

The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into the central nervous system (CNS). Nanoparticles have been able to partly overcome this obstacle and can thus improve drug delivery across the BBB. Furthermore, focused ultrasound in combination with gas filled microbubbles has opened the BBB in a temporospatial manner in animal models, thus facilitating drug delivery across the BBB. In the current study we combine these two approaches in our quest to develop a novel, generic method for drug delivery across the BBB and into the CNS. Nanoparticles were synthesized using the polymer poly(butyl cyanoacrylate) (PBCA), and such nanoparticles have been reported to cross the BBB to some extent. Together with proteins, these nanoparticles self-assemble into microbubbles. Using these novel microbubbles in combination with focused ultrasound, we successfully and safely opened the BBB transiently in healthy rats. Furthermore, we also demonstrated that the nanoparticles could cross the BBB and deliver a model drug into the CNS.

Novel delivery approaches for cancer therapeutics

Currently, a majority of cancer treatment strategies are based on the removal of tumor mass mainly by surgery. Chemical and physical treatments such as chemo- and radiotherapies have also made a major contribution in inhibiting rapid growth of malignant cells. Furthermore, these approaches are often combined to enhance therapeutic indices. It is widely known that surgery, chemo- and radiotherapy also inhibit normal cells growth. In addition, these treatment modalities are associated with severe side effects and high toxicity which in turn lead to low quality of life. This review encompasses novel strategies for more effective chemotherapeutic delivery aiming to generate better prognosis. Currently, cancer treatment is a highly dynamic field and significant advances are being made in the development of novel cancer treatment strategies. In contrast to conventional cancer therapeutics, novel approaches such as ligand or receptor based targeting, triggered release, intracellular drug targeting, gene delivery, cancer stem cell therapy, magnetic drug targeting and ultrasound-mediated drug delivery, have added new modalities for cancer treatment. These approaches have led to selective detection of malignant cells leading to their eradication with minimal side effects. Lowering multi-drug resistance and involving influx transportation in targeted drug delivery to cancer cells can also contribute significantly in the therapeutic interventions in cancer.

Targeted nanomedicine for prostate cancer therapy: docetaxel and curcumin co-encapsulated lipid-polymer hybrid nanoparticles for the enhanced anti-tumor activity in vitro and in vivo

OBJECTIVE

Docetaxel (DTX) remains the only effective drug for prolonging survival and improving quality of life of metastatic castration-resistant prostate cancer (mCRPC) patients. Combination anticancer therapy encapsulating DTX and another extract of traditional Chinese medicine is one nano-sized drug delivery system promising to generate synergistic anticancer effects, to maximize the treatment effect, and to overcome multi-drug resistance. The purpose of this study is to construct lipid-polymer hybrid nanoparticles (LPNs) as nanomedicine for co-encapsulation of DTX and curcumin (CUR).

METHODS

DTX and CUR co-encapsulated LPNs (DTX-CUR-LPNs) were constructed. DTX-CUR-LPNs were evaluated in terms of particles size, zeta potential, drug encapsulation, and drug delivery. The cytotoxicity of the LPNs was evaluated on PC-3 human prostate carcinoma cells (PC3 cells) by MTT assays. In vivo anti-tumor effects were observed on the PC3 tumor xenografts in mice.

RESULTS

The particle size of DTX-CUR-LPNs was 169.6 nm with a positive zeta potential of 35.7 mV. DTX-CUR-LPNs showed highest cytotoxicity and synergistic effect of two drugs in tumor cells in vitro. In mice-bearing PC-3 tumor xenografts, the DTX-CUR-LPNs inhibited tumor growth to a greater extent than other contrast groups, without inducing any obvious side effects.

CONCLUSION

According to these results, the novel nanomedicine offers great promise for the dual drugs delivery to the prostate cancer cells, showing the potential of synergistic combination therapy for prostate cancer.

Trigger responsive polymeric nanocarriers for cancer therapy

Conventional chemotherapy for the treatment of cancer has limited specificity when administered systemically and is often associated with toxicity issues. Enhanced accumulation of polymeric nanocarriers at a tumor site may be achieved by passive and active targeting. Incorporation of trigger responsiveness into these polymeric nanocarriers improves the anticancer efficacy of such systems by modulating the release of the drug according to the tumor environment. Triggers used for tumor targeting include internal triggers such as pH, redox and enzymes and external triggers such as temperature, magnetic field, ultrasound and light. While internal triggers are specific cues of the tumor microenvironment, external triggers are those which are applied externally to control the release. This review highlights the various strategies employed for the preparation of such trigger responsive polymeric nanocarriers for cancer therapy and provides an overview of the state of the art in this field.