The world’s smallest computer (around a trillion can fit in a dropof water) might one day go on record again as the tiniest medical kit.Made entirely of biological molecules, this computer was successfullyprogrammed to identify - in a test tube - changes in the balance ofmolecules in the body that indicate the presence of certain cancers, todiagnose the type of cancer, and to react by producing a drug moleculeto fight the cancer cells.
The Weizmann Institute of Science team that developed the computerpublished these results today in Nature. Headed by Prof. Ehud Shapiro,of the Departments of Computer Sciences and Applied Mathematics, andBiological Chemistry, the team included research students YaakovBenenson, Binyamin Gil, Uri Ben-Dor and Dr. Rivka Adar. Shapiropresented the team’s findings today at the Brussels symposium “Life, aNobel Story,” in which Nobel Laureates and others addressed the futureof the life sciences.
As in previous biological computers produced in Shapiro’s lab,input, output and “software” are all composed of DNA, the material ofgenes, while DNA-manipulating enzymes are used as “hardware.” Thenewest version’s input apparatus is designed to assess concentrationsof specific RNA molecules, which may be overproduced or under produced,depending on the type of cancer. Using pre-programmed medicalknowledge, the computer then makes its diagnosis based on the detectedRNA levels. In response to a cancer diagnosis, the output unit of thecomputer can initiate the controlled release of a single-stranded DNAmolecule that is known to interfere with the cancer cell’s activities,causing it to self-destruct.
In one series of test-tube experiments, the team programmed thecomputer to identify RNA molecules that indicate the presence ofprostate cancer and, following a correct diagnosis, to release theshort DNA strands designed to kill cancer cells. Similarly, they wereable to identify, in the test tube, the signs of one form of lungcancer. One day in the future, they hope to create a “doctor in acell”, which will be able to operate inside a living body, spot diseaseand apply the necessary treatment before external symptoms even appear.
The original version of the biomolecular computer (also created in atest tube) capable of performing simple mathematical calculations, wasintroduced by Shapiro and colleagues in 2001. An improved system, whichuses its input DNA molecule as its sole source of energy, was reportedin 2003 and was listed in the 2004 Guinness Book of World Records asthe smallest biological computing device.
Shapiro: “It is clear that the road to realizing our vision is along one; it may take decades before such a system operating inside thehuman body becomes reality. Nevertheless, only two years ago wepredicted that it would take another 10 years to reach the point wehave reached today.”
Prof. Ehud Shapiro's research is supported by the M.D. MorossInstitute for Cancer Research, the Samuel R. Dweck Foundation, theDolfi and Lola Ebner Center for Biomedical Research, the Benjamin andSeema Pulier Charitable Foundation, and the Robert Rees Fund forApplied Research.
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