A team of scientists from the National University of Singapore (NUS) has developed a way to wirelessly deliver light into deep regions of the body to activate light-sensitive drugs for photodynamic therapy (PDT).
While PDT is a powerful light-induced cancer treatment, it is often limited to surface cancers due to the low penetration of light through biological tissue. This wireless approach of light delivery enables PDT to be used on the inner organs of the body with fine control. This technology could potentially enable PDT to be used to treat a wider range of cancers, such as brain and liver cancer.
The study was led by Professor Zhang Yong and Assistant Professor John Ho, who are respectively from the Department of Biomedical Engineering and Department of Electrical and Computer Engineering at NUS Faculty of Engineering. The findings of the study were published in the scientific journal Proceedings of the National Academy of Sciences (PNAS) on 29 January 2018.
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Asst Prof Ho said, "Our approach of light delivery will provide significant advantages for treating cancers with PDT in previously inaccessible regions. Powered wirelessly, the tiny implantable device delivers doses of light over long time scales in a programmable and repeatable manner. This could potentially enable the therapies to be tailored by the clinician during the course of treatment." Asst Prof Ho is also a Principal Investigator at the Biomedical Institute for Global Health Research and Technology (BIGHEART) at NUS.
Understanding photodynamic therapy
PDT is a treatment method that uses a light sensitive drug, called a photosensitiser, that is triggered by a specific wavelength of light, to produce a form of oxygen that kills nearby cells. This provides a precision approach to cancer therapy that overcomes many of the whole-body side effects of classical drugs such as chemotherapy. In addition to directly killing cancer cells, PDT shrinks or destroys tumours by damaging blood vessels in the tumour, preventing the cancer cells from receiving necessary nutrients. PDT may also activate the immune system to attack the tumour cells.
However, PDT has so far been limited to the treatment of surface cancers. Traditional light sources such as light-emitting diodes (LEDs) or lasers may be used for surface tumours, such as skin cancer, but the low penetration of light through tissue limits the depth to less than a centimetre. For the inner lining of some organs, such as the oesophagus, an endoscope - a thin, lighted tube used to look at tissues inside the body - can be used to insert a fibre optic cable, but other regions cannot be easily accessed by this way. For organs such as the brain or liver, the organ must be exposed by surgery before PDT can be used.
