Tung Thanh Pham

Combined phototherapy in anti-cancer treatment: therapeutics design and perspectives

Photodynamic (PDT) and photothermal (PTT) therapy are proven effective strategies for the treatment of cancer. PDT, a photochemistry-based therapy, utilises light energy based photosensitiser for the production of cytotoxic species via electron transfer to biological substrates and potential excitation or energy transfer to molecular oxygen. On the other hand, PTT utilises substances that can convert light energy into heat for efficient tumour ablation. This review provides an insight into the current research investigations of different nanocarriers utilising the synergistic effects of PTT and PDT for anticancer therapy.

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-co-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method

Tacrolimus-loaded poly(lactic-co-glycolic acid) microspheres (TAC-PLGA-M) can be administered for the long-term survival of transplanted organs due to their immunosuppressive activity. The purpose of our study was to optimize the parameters of the electrospray method, and to prepare TAC-PLGA-M with a high payload and desirable release properties. TAC-PLGA-M were prepared using the electrospray method. In vitro characterization and evaluation were performed using scanning electron microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy. Drug-loading efficiency was greater than 80% in all formulations with a maximum loading capacity of 16.81±0.37%. XRD and DSC studies suggested that the drug was incorporated in an amorphous state or was molecularly dispersed in the microspheres. The in vitro release study showed prolonged release patterns. TAC-PLGA-M with enhanced drug loading and prolonged-release patterns were successfully prepared using the electrospray method.

Incorporation of chemotherapeutic agent and photosensitizer in a low temperature-sensitive liposome for effective chemo-hyperthermic anticancer activity

ABSTRACT Objectives: In this study, we combined chemo- and hyperthermia therapy in a low temperature-sensitive liposome (LTSL) for potential cancer treatment. Methods: Docetaxel (DOC) and indocyanine green (ICG) as a therapeutic agent and photosensitizer, respectively, were incorporated in a low temperature-sensitive liposome (LTSL/DI). Nanoparticles were evaluated for the physicochemical characterizations, in vitro uptake and cytotoxicity, and furthermore in vivo anticancer activity. Results: The particle size of LTSL/DI was 130.8 ± 2.3 nm, and its drug release profile was pH- and temperature-dependent, which are effective for tumor targeting. The in vitro anticancer activity of LTSL/DI was significantly enhanced compared with free DOC in SCC-7 and MCF-7 cell lines. Interestingly, near-infrared laser irradiation after the treatment resulted in better anticancer activity than in the non-irradiated condition. The in vivo tumor regression effect of LTSL/DI in combination with NIR irradiation was much greater compared with the control group in SCC-7 tumor-bearing mice. After intratumoral injection of LTSL/DI, local heat induced by NIR irradiation and the localized docetaxel burst release could completely ablate the tumor, and inhibit its recurrence. Conclusions: These results suggest LTSL/DI formulation as a potential therapeutic strategy with effectively localized anti-tumor activity and low risk of side effect to non-target organs.

Engineered islet cell clusters transplanted into subcutaneous space are superior to pancreatic islets in diabetes

An alternative route for pancreatic islet transplantation is the subcutaneous space; however, inadequate vascularization in the subcutaneous space limits the availability of oxygen and nutrients to the subcutaneously transplanted islets, which leads to the development of a necrotic core in the islets, thereby causing islet dysfunction. Thus, we aimed to prevent the early apoptosis of pancreatic islets after transplantation into subcutaneous space by preparing islet clusters of appropriate size. We prepared fully functional islet cell clusters (ICCs) by using the hanging‐drop technique. We optimized the size of ICCs on the basis of viability and functionality after culture in an hypoxic environment. We transplanted ICCs into the subcutaneous space of diabetic mice and evaluated the viability of the islets at the transplantation site. In an hypoxic environment, ICCs exhibited improved viability and functionality compared with control islets. ICCs, upon transplantation into the hypoxic subcutaneous space of diabetic mice, showed better glycemic control compared with control islets. Live/dead imaging of the islets after retrieval from the transplanted area revealed significantly reduced apoptosis in ICCs. Transplantation of ICCs may be an attractive strategy to prevent islet cell apoptosis that results from nonimmune‐mediated physiologic stress at the transplantation site.—Pathak, S., Regmi, S., Gupta, B., Pham, T. T., Yong, C. S., Kim, J. O., Yook, S., Kim, J.‐R., Park, M. H., Bae, Y. K., Jeong, J.‐H. Engineered islet cell clusters transplanted into subcutaneous space are superior to pancreatic islets in diabetes. FASEB J. 31, 5111–5121 (2017). www.fasebj.org

Multifunctional nanoparticles as somatostatin receptor-targeting delivery system of polyaniline and methotrexate for combined chemo–photothermal therapy

Lanreotide (LT), a synthetic analog of somatostatin, has been demonstrated to specifically bind to somatostatin receptors (SSTRs), which are widely overexpressed in several types of cancer cells. In this study, we incorporated a chemotherapeutic agent, methotrexate (MTX), and a photosensitizer material, polyaniline (PANI), into hybrid polymer nanoparticles (NPs), which could target cancer cells after conjugation with LT (LT-MTX/PANI NPs). The successful preparation of LT-MTX/PANI NPs was confirmed by a small particle size (187.9 ± 3.2 nm), a polydispersity index of 0.232 ± 0.011, and a negative ζ potential of -14.6 ± 1.0 mV. Notably, LT-MTX/PANI NPs showed a greater uptake into SSTR-positive cancer cells and thereby better inhibited cell viability and induced higher levels of apoptosis than MTX, PANI NP, and MTX/PANI NP treatments did. In addition, the heat associated with the burst drug release induced by near-infrared (NIR) irradiation resulted in remarkably enhanced cell apoptosis, which was confirmed by an increase in the expression levels of apoptotic marker proteins. In agreement with the in vitro results, the administration of the SSTR-targeting NPs, followed by NIR exposure, to xenograft tumor-bearing mice resulted in an improved suppression of tumor development compared to that shown by MTX, PANI NPs, and MTX/PANI NPs, as well as by LT-MTX/PANI NPs without photothermal therapy. Thus, the SSTR-targeting NPs could be a promising delivery system for the effective treatment of SSTR-positive cancers. STATEMENT OF SIGNIFICANCE Somatostatin receptors are widely overexpressed in several types of cancer cells. In this study, we designed nanoparticles for targeted delivery of chemotherapeutic agents to tumor sites by conjugating hybrid polymers with a synthetic analog of somatostatin, specifically binding to somatostatin receptors. In addition, a photosensitizer material, polyaniline, was incorporated into the nanoparticles for combined chemo-photothermal therapy. The results demonstrated clear advantages of the newly designed targeted nanoparticles over their non-targeted counterparts or a free chemotherapeutic drug in inhibiting the viability of cancer cells in vitro and targeting/suppressing the tumor growth in an animal xenograft model. The study suggests that the designed nanoparticles are a promising delivery system for the effective treatment of somatostatin receptor-positive cancers.

Tissue adhesive FK506–loaded polymeric nanoparticles for multi–layered nano–shielding of pancreatic islets to enhance xenograft survival in a diabetic mouse model

This study aims to develop a novel surface modification technology to prolong the survival time of pancreatic islets in a xenogenic transplantation model, using 3,4-dihydroxyphenethylamine (DOPA) conjugated poly(lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG) nanoparticles (DOPA-NPs) carrying immunosuppressant FK506 (FK506/DOPA-NPs). The functionalized DOPA-NPs formed a versatile coating layer for antigen camouflage without interfering the viability and functionality of islets. The coating layer effectively preserved the morphology and viability of islets in a co-culture condition with xenogenic lymphocytes for 7 days. Interestingly, the mean survival time of islets coated with FK506/DOPA-NPs was significantly higher as compared with that of islets coated with DOPA-NPs (without FK506) and control. This study demonstrated that the combination of surface camouflage and localized low dose of immunosuppressant could be an effective approach in prolonging the survival of transplanted islets. This newly developed platform might be useful for immobilizing various types of small molecules on therapeutic cells and biomaterial surface to improve the therapeutic efficacy in cell therapy and regenerative medicine.

Delivery of Pancreatic Islets and Single Dose Local Immune Suppression Into Subcutaneous Space Using Injectable Hydrogel Provides Indefinite Survival of the Graft in Mouse Model of Diabetes

Introduction Pancreatic islet transplantation is a promising technique to treat type 1 diabetes. Long-term survival of the graft is required for a successful islet transplantation. Repeated use of immunosuppressive drugs after organ/cell transplantation often leads to severe adverse effects including nephrotoxicity, hepatotoxicity, and opportunistic infections. Thus, development of a local immunosuppression protocol is necessary to improve the islet graft survival in clinics. Materials and Methods Pancreatic islets from Sprague-Dawley rats were transplanted into the subcutaneous space of B6 mice using injectable hydrogel. Three major groups were prepared for transplantation. (1) Islets transplanted FK506-loaded poly(lactic-co-glycolic acid) microspheres (10 mg/kg), (2) Islets transplanted with clodronate liposomes (6.25 mg/kg), and (3) Islet transplanted with the combination of both immune suppressants. The suspension of islets and immune suppressants in Matrigel was then injected into the subcutaneous space over the flanks of streptozocin-induced diabetic mice. Results Islets transplanted without any immunosuppression were rejected within two weeks. In contrast, the islets transplanted with the single immunosuppressive regimen of FK506 or clodronate improved survival rate compared with that of the control mice. More interestingly, the graft transplanted using the combination of both immune suppressants survived indefinitely. Immunological studies revealed that the immunosuppressive cocktail inhibited the proliferation of immune cells residing at the peripheral lymph nodes. Interestingly, the systemic immune system of the transplanted mice remained unaffected. Furthermore, histochemical analysis revealed the intact morphology of the islets at the transplanted site when codelivered with the immunosuppressant. Discussion Antigen presenting cells and T-cells orchestrate the immune rejection cascade. Macrophage depletion by the liposomal clodronate and the inhibition of T-cell activation by FK506 completely blocked the immune rejection cascade in the immune competent mice. The inhibition of immune stimulation in the peripheral lymph nodes improved the islet grafted into the subcutaneous space. Thus, the use of local immune suppression is an effective approach to enhance the survival of the transplanted islets. Conclusion We developed a protocol for the local codelivery of pancreatic islets and immune suppressive agents. Indefinite graft survival was obtained with the use of macrophage depleting agent and T-cell inhibitor. The single dose of local immune suppression during transplantation may avoid toxic effects associated with a long-term use of immune suppressive agents in clinics. National Research Foundation of Korea (NRF) Grant nos: 2015R1A5A2009124 and 2017R1D1A1B03027831. Korea Health Industry Development Institute (KHIDI) Grant no: HI16C1767.

Single synchronous delivery of FK506-loaded polymeric microspheres with pancreatic islets for the successful treatment of streptozocin-induced diabetes in mice

Abstract Immune rejection after transplantation is common, which leads to prompt failure of the graft. Therefore, to prolong the survival time of the graft, immunosuppressive therapy is the norm. Here, we report a robust immune protection protocol using FK506-loaded microspheres (FK506M) in injectable hydrogel. Pancreatic islets were codelivered with the FK506M into the subcutaneous space of streptozocin-induced diabetic mice. The islets codelivered with 10 mg/kg FK506M maintained normal blood glucose levels during the study period (survival rate: 60%). However, transplantation of islets and FK506M at different sites hardly controlled the blood glucose level (survival rate: 20%). Immunohistochemical analysis revealed an intact morphology of the islets transplanted with FK506M. In addition, minimal number of immune cells invaded inside the gel of the islet-FK506M group. The single injection of FK506M into the local microenvironment effectively inhibited immune rejection and prolonged the survival time of transplanted islets in a xenograft model.