Chlorin Nanoparticles for Tissue Diagnostics and Photodynamic Therapy

Co-Encapsulation of Methylene Blue and PARP-Inhibitor into Poly(Lactic-Co-Glycolic Acid) Nanoparticles for Enhanced PDT of Cancer

The development of resistance against photodamage triggered by photodynamic therapy (PDT) is ascribed mainly to the cellular redox defenses and repair. If the tumor tissue is not promptly eliminated by the first few PDT sessions, PDT-resistance can be favored, challenging the efficacy of the treatment. Although the mechanism of PDT resistance is still unclear, in vitro assays have evidenced that it can be developed through the PARP damage-repair signaling pathway. Therefore, inhibition of poly(adenosine diphosphate (ADP)-ribose) polymerase (PARP) has the potential to increase PDT efficacy. This work reports on the synthesis of a controlled release system of a photosensitizer, methylene blue (MB) and a PARP-inhibitor, the veliparib. MB and veliparib were co-encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (VMB-NPs). A colloidal stable aqueous suspension of nanoparticles was obtained. The average hydrodynamic diameter was 90 nm and a narrow size distribution was obtained, with a polydispersity index (PDI) of 0.08. The release kinetics of MB and veliparib from VMB-NPs showed an initial burst of 8.7% and 58.3% release of the total amounts of MB and veliparib respectively, in the first 6 h, and a delayed release of up to 11.3% and 70%, in 19 days, for MB and veliparib, respectively. The VMB-NPs showed no cytotoxicity in the dark but the viability of B16F10-Nex2 cells decreased by 36% when the cells were irradiated (102 J/cm², 660 nm) and treated with VMB-NPs containing 1.0 µM of MB and 8.3 µM of veliparib. Considering the increased photoactivity even at low MB and veliparib concentrations and the absence of cytotoxicity in dark, the co-encapsulation of MB and veliparib was shown to be a promising strategy to improve the PDT efficacy.

New approaches to diagnostics and treatment of cholangiocellular cancer based on photonics methods

Cholangiocellular cancer (CCC) is an oncological disease of the bile ducts characterized by a high mortality rate. To date, the use of standard methods for the diagnosis and treatment of CCC has not been able to reduce mortality from this disease. This work presents the results of fluorescence diagnostics (FD), which consists in using a modified optical fiber and photodynamic therapy (PDT) using a therapeutic laser instead of a low-intensity laser. This technique was tested on 43 patients in a clinical setting. The results obtained indicate a direct correlation between spectroscopic and video FD methods. Furthermore, a direct correlation was found between the photobleaching of a chlorin e6-based photosensitizer, with the commercial names of Photolon Radachlorin and Photoran and stricture regression. Our findings demonstrate the possibility of using a therapeutic laser with a wavelength of 660 nm for both diagnosis and treatment of bile ducts cancer, which results in a significant reduction of the operation time without decreasing its effectiveness.

Conjugate of chlorin е6 with iron bis(dicarbollide) nanocluster: synthesis and biological properties

Background: Efficiency of both photodynamic and boron-neutron capture anticancer therapies (BNCT) depends on the properties of the used photo- and neutronsensitizer. We report on the synthesis and properties of the advanced photo- and neutronsensitizer designed as a conjugate of chlorin e₆ with iron bis(dicarbollide) nanocluster. Results: The conjugate is shown to accumulate efficiently in rat glioblastoma C6 cells delivering >10⁹ boron atoms per cell and thus meeting requirements for BNCT agents, to provide photoinduced 50% death of C6 cells at 35 ± 3 nM, to be not toxic for cells without activating stimulus. Conclusions: The conjugate is a prospective theranostic agent for photodynamic, BNCT and fluorescent diagnostics of tumors.

Trials of a Fluorescent Endoscopic Video System for Diagnosis and Treatment of the Head and Neck Cancer

This article presents the results of intraoperative fluorescent diagnostics via the endoscopic system for assessing the quality of photodynamic therapy (PDT) of head and neck cancer. The diagnosis and PDT procedures were performed on the five patients with malignant neoplasms of the vocal cords, lateral surface of the tongue, and trachea and cancer of the left parotid salivary gland. Molecular form of chlorin E6 (Ce6) was intravenously administered with a 1.0–1.1 mg/kg concentration for PDT. Fluorescent diagnostics (FD) was conducted before PDT and after PDT procedures. Control of PDT efficiency was carried out by evaluating the photobleaching of the drug (photosensitizer). The method of intraoperative fluorescent imaging allows determining the exact location of the tumor and its boundaries. The assessment of photosensitizer photobleaching in real time regime allows making quick decisions during PDT procedure, which helps improving the quality of patients’ treatment. The results showed the convenience of endoscopic fluorescent video system in various nosologies of head and neck cancer. Therefore, this diagnostic approach will improve the effectiveness of cancer treatment.

Photoactive Liposomal Formulation of PVP-Conjugated Chlorin e6 for Photodynamic Reduction of Atherosclerotic Plaque

Background: Liposomes serve as delivery systems for biologically active compounds. Existing technologies inefficiently encapsulate large hydrophilic macromolecules, such as PVP-conjugated chlorin e6 (Photolon). This photoactive drug has been widely tested for therapeutic applications, including photodynamic reduction of atherosclerotic plaque. Methods: A novel formulation of Photolon was produced using “gel hydration technology”. Its pharmacokinetics was tested in Sus scrofa f. domestica. Its cellular uptake, cytotoxicity, and ability to induce a phototoxic reaction were demonstrated in J774A.1, RAW264.7 macrophages, and vascular smooth muscle (T/G HA-VSMC) as well as in vascular endothelial (HUVEC) cells. Results: Developed liposomes had an average diameter of 124.7 ± 0.6 nm (polydispersity index (PDI) = 0.055) and contained >80% of Photolon). The half-life of formulation in S. scrofa was 20 min with area under the curve (AUC) equal to 14.7. The formulation was noncytotoxic in vitro and was rapidly (10 min) and efficiently accumulated by macrophages, but not T/G HA-VSMC or HUVEC. The accumulated quantity of photosensitizer was sufficient for induction of phototoxicity in J774A.1, but not in T/G HA-VSMC. Conclusions: Due to the excellent physical and pharmacokinetic properties and selectivity for macrophages, the novel liposomal formulation of Photolon is a promising therapeutic candidate for use in arteriosclerosis treatment when targeting macrophages but not accompanying vascular tissue is critical for effective and safe therapy.