Wireless sequential dual light delivery for programmed PDT in vivo.

Using photodynamic therapy (PDT) to treat deep-seated cancers is limited due to inefficient delivery of photosensitizers and low tissue penetration of light. Polymeric nanocarriers are widely used for photosensitizer delivery, while the self-quenching of the encapsulated photosensitizers would impair the PDT efficacy. Furthermore, the generated short-lived reactive oxygen spieces (ROS) can hardly diffuse out of nanocarriers, resulting in low PDT efficacy. Therefore, a smart nanocarrier system which can be degraded by light, followed by photosensitizer activation can potentially overcome these limitations and enhance the PDT efficacy. A light-sensitive polymer nanocarrier encapsulating photosensitizer (RB-M) was synthesized. An implantable wireless dual wavelength microLED device which delivers the two light wavelengths sequentially was developed to programmatically control the release and activation of the loaded photosensitizer. Two transmitter coils with matching resonant frequencies allow activation of the connected LEDs to emit different wavelengths independently. Optimal irradiation time, dose, and RB-M concentration were determined using an agent-based digital simulation method. In vitro and in vivo validation experiments in an orthotopic rat liver hepatocellular carcinoma disease model confirmed that the nanocarrier rupture and sequential low dose light irradiation strategy resulted in successful PDT at reduced photosensitizer and irradiation dose, which is a clinically significant event that enhances treatment safety.

Light-responsive smart nanocarriers for wirelessly controlled photodynamic therapy for prostate cancers.

Photodynamic therapy (PDT) is an effective non-invasive or minimally invasive treatment method against different tumors. Loading photosensitizers in nanocarriers can potentially increase their accumulation in tumor sites. However, the PDT efficacy may be hindered because of self-quenching of the encapsulated photosensitizer and the small diffusion radii of the generated reactive oxygen species (ROS). Herein, light responsive nano assemblies composed of (Polyethylene glycol)-block-poly(4,5-dimethoxy-2-nitrobenzylmethacrylate) (PEG-b-PNBMA) were designed and loaded with the photosensitizer, Rose Bengal lactone (RB), to act as a smart nanocarrier (RB-M) for the delivery of the photosensitizer. A wirelessly activated light-emitting diode (LED) implant was designed to programmatically induce the release of the loaded RB first, followed by activating PDT after diffusion of RB into the cytoplasm. The results showed that sequential '405-580 nm' irradiation of the RB-M treated 22RV1 cells resulted in the highest PDT outcome among different irradiation protocols. The combination of this smart nanocarrier and sequential '405-580 nm' irradiation strategy exhibited good PDT efficacy against 2D 22RV1 prostate cancer cells as well as 3D cancer cell spheroids. This platform overcomes the light penetration limitations in PDT, and can potentially be applied in cancer bearing patients who are unfit for chemotherapy. STATEMENT OF SIGNIFICANCE: Nanocarriers for the delivery of photosensitizer in photodynamic therapy may result in relatively low therapeutic efficacy because of self-quenching of the encapsulated photosensitizer and the small diffusion radii of the generated reactive oxygen species (ROS). Light responsive smart nanocarriers can potentially overcome this challenge. In this study, a light responsive polymer (Polyethylene glycol)-block-poly(4,5-dimethoxy-2-nitrobenzylmethacrylate) (PEG-b-PNBMA) was synthesized and utilized to fabricate the smart nanocarrier. A wirelessly activated light-emitting diode (LED) implant was designed for light delivery in deep tissue. This new approach permits wirelessly and programmatically control of photosensitizer release and PDT activation under deep tissue, thus significantly enhancing PDT efficacy against prostate cancer cells as well as 3D cancer cell spheroids. This design should have a significant impact on controllable PDT under deep tissue.

Internalization of Mycobacterium bovis, Bacillus Calmette Guerin, by bladder cancer cells is cytotoxic.

Instillation of Bacillus Calmette Guerin (BCG) into the bladder is the standard treatment for superficial bladder cancer. It leads to a local inflammatory response due to the release of cytokines and influx of immune cells to the tumor site. Although the presence of an intact immune system is an essential criterion for successful therapy, attachment of the bacteria to the bladder urothelial is just as important. The purpose of our study is to determine the role of bacterial internalization by epithelial cells. Transfection of the alpha5 integrin gene into the BCG unresponsive bladder cancer cell line, RT4, caused an increase in bacterial uptake and also increased cell death. Treatment of cells with cycloheximide did not prevent bacterial internalization but blocked its cytotoxic effect suggesting that unlike cell death, the process of bacterial internalization does not require new protein synthesis. Our data also show that the bacteria secretory products can prevent its own internalization. The extract prepared from lyophilized BCG altered the phosphorylation status of the focal adhesion kinase which is responsible for cellular endocytosis. Therefore, bacterial phosphatases may be present in the bacterial extract. Their activity may inhibit BCG internalization. Thus washing the reconstituted bacteria to remove the enzymes before instillation into the bladder might improve the therapeutic outcome of intravesical BCG therapy.

Lactobacillus species is more cytotoxic to human bladder cancer cells than Mycobacterium Bovis (bacillus Calmette-Guerin).

PURPOSE: We determined if Lactobacillus species has growth inhibitory effects in human bladder cancer cell lines and how this effect compares with the known effects of Mycobacterium bovis, that is bacillus Calmette-Guerin (BCG). MATERIALS AND METHODS: The growth of MGH and RT112 cells were determined by cell counts after 24, 48 and 72 hours of exposure to L. casei strain Shirota (Yakult, Singapore) or L. rhamnosus strain GG (National Collection of Industrial and Marine Bacteria, Ltd., Aberdeen, Scotland) (1 x 10 and 1 x 10 cfu) or BCG (1 x 10 cfu) in the presence and absence of streptomycin. Annexin-V was used to monitor the presence of pre-apoptotic cells. RESULTS: L. rhamnosus GG inhibited MGH proliferation and it was cytotoxic to RT112 cells (p <0.05). L. casei Shirota was cytotoxic to the 2 cell lines (p <0.05). BCG had a similar cytotoxic effect in MGH cells as Lactobacillus species but was not as effective in RT112 cells. Streptomycin abrogated the cytotoxic effect of Lactobacillus species but not that of BCG. Cytotoxic activity was not found in Lactobacilli culture supernates but it was induced in the presence of mammalian cells. L. rhamnosus GG induced apoptosis in RT112 but not in MGH cells. No apoptotic cells were detected after treatment with L. casei Shirota. CONCLUSIONS: Lactobacillus species induced cytotoxic effects in bladder cancer cells. Unlike BCG, it requires bacterial protein synthesis. Like BCG, L. casei Shirota induces cell death primarily via necrosis. The cytoxicity of these lactobacilli in bladder cancer cells raises the possibility of using this species of bacteria as intravesical agents for treating bladder cancer.