A 'nanomachine' for surgery with no incision

A surgical operation has long been considered one of the first options in cancer treatment; however, a number of issues have been recognized: a highly invasive procedure; a decline in the Quality of Life (QOL) after an operation; the possibility of a recurrence due to missed cancer cells; extended hospitalization, sometimes for as long as one month; and the economic costs. Against such a background, recently neutron capture therapy(1) has been drawing attention. By irradiating the affected area with a pinpoint light beam, ultrasonic waves, and thermal neutrons, which can be safely administered to living organisms, specific chemical compounds (neutron sensitizer elements) are activated and kill the cancer cells. This therapy has a lower burden on patients. However, the technological development to deliver the neutron sensitizer molecules to cancer cells has been a great challenge. A research team led by Professor Kazunori Kataoka, Department of Bioengineering, School of Engineering, The University of Tokyo (concurrently serving as the Director of the Innovation Center of NanoMedicine, Kawasaki Institute of Industry Promotion), and Professor Nobuhiro Nishiyama, Chemical Resources Laboratory, Tokyo Institute of Technology, has successfully developed a nano crystal aggregate (nanomachine) technology to deliver a gadolinium complex (Gd-DTPA or magnevist) — broadly used as an MRI contrast agent — to the affected area ("Hybrid Calcium Phosphate-Polymeric Micelles Incorporating Gadolinium Chelates for Imaging-Guided Gadolinium Neutron Capture Tumor Therapy"). More specifically, it is a drug delivery system (DDS) whereby a nano-level contrast agent (Gd)-DTPA is prepared, and introduced into the interior of calcium phosphate, a bone constituent, and is delivered to cancer tissues. The research team has clarified that selective accumulation of the developed nanomachine in a cancer tumor enables contrast imaging of a solid cancer. Moreover, when the Team applied the nanomachine to cancer neutron capture therapy, they confirmed a remarkable curative effect. This nanomachine therapy enables an imaging-guided thermal neutron irradiation treatment; thus it can be expected to lead to a reliable cancer treatment with no missed cancer cells. The realization of surgery with no incision (chemical surgery) by nanomachine allows us to anticipate outpatient treatment with no need of hospitalization.