Tuesday, June 20, 2017

Cancer nanoparticle-based photodynamic therapy developed using mPEG-PLA from PolySciTech

Treating cancer is complicated by several features of the disease including metastasis, drug-resistance, and biological similarity of cancerous cells to healthy ones. Conventional chemotherapy is typically effective at killing cancer cells, however it lacks the capacity to discriminate between cancerous cells and healthy ones. This is where combination therapies can have an advantage. For phototherapy, instead of delivering a toxic molecule (such as cisplatin or paclitaxel) a photosensitizer is delivered. This molecule is inactive, unless it is activated by a very specific frequency of light which activates it killing the cell. The overall method here is to systematically deliver the photosensitizer to a patient and then selectively illuminate the portion where the cancer is located so only the cancer is affected. Recently, researchers working jointly at Northeastern University, George Washington University, and Wenzhou Medical University utilized mPEG-PLA from PolySciTech (www.polyscitech.com) (PolyVivo AK021) to create protoporphyrin IX (a photosensitizer) loaded nanoparticles. They combined these with photodynamic therapy and tested this system as a treatment for melanoma.  This research holds promise to improve the treatment of melanoma, especially malignant or drug-resistant forms. Read more: Wang, Mian, Benjamin M. Geilich, Michael Keidar, and Thomas J. Webster. "Killing malignant melanoma cells with protoporphyrin IX-loaded polymersome-mediated photodynamic therapy and cold atmospheric plasma." International Journal of Nanomedicine 12 (2017): 4117. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459981/

“Abstract: Traditional cancer treatments contain several limitations such as incomplete ablation and multidrug resistance. It is known that photodynamic therapy (PDT) is an effective treatment for several tumor types especially melanoma cells. During the PDT process, protoporphyrin IX (PpIX), an effective photosensitizer, can selectively kill cancer cells by activating a special light source. When tumor cells encapsulate a photosensitizer, they can be easily excited into an excited state by a light source. In this study, cold atmospheric plasma (CAP) was used as a novel light source. Results of some studies have showed that cancer cells can be effectively killed by using either a light source or an individual treatment due to the generation of reactive oxygen species and electrons from a wide range of wavelengths, which suggest that CAP can act as a potential light source for anticancer applications compared with UV light sources. Results of the present in vitro study indicated for the first time that PpIX can be successfully loaded into polymersomes. Most importantly, cell viability studies revealed that PpIX-loaded polymersomes had a low toxicity to healthy fibroblasts (20% were killed) at a concentration of 400 µg/mL, but they showed a great potential to selectively kill melanoma cells (almost 50% were killed). With the application of CAP posttreatment, melanoma cell viability significantly decreased (80% were killed) compared to not using a light source (45% were killed) or using a UV light source (65% were killed). In summary, these results indicated for the first time that PpIX-loaded polymersomes together with CAP posttreatment could be a promising tool for skin cancer drug delivery with selective toxicity toward melanoma cells sparing healthy fibroblasts. Keywords: melanoma, polymersomes, protoporphyrin IX, cold atmospheric plasma, photo-dynamic therapy”
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