Mi­cro­scopic DNA ro­bots could choke off tu­mours


If hu­mans turn out to be any­thing like mi­cropigs then sci­en­tists may have de­vel­oped a po­tent new weapon in the war on can­cer.

The blood sup­ply that tu­mours rely on for oxy­gen and en­ergy can be choked off by fleets of "nanorobots" made out of DNA, early ex­per­i­ments show. The ma­chines, which are so small that about 20 mil­lion would fit on to a pin­head, have shrunk hu­man lung, breast and ovar­ian can­cers in mice.

They also ap­peared to have no harm­ful side-ef­fects when they were in­jected into Bama minia­ture pigs, which are roughly the size of an Airedale ter­rier but have a hu­man-like phys­i­ol­ogy.

While there is much to be done be­fore the treat­ment can be tested on hu­mans, the study sug­gests that the long-cher­ished dream of heal­ing the body with tiny au­ton­o­mous con­trap­tions could be near­ing fruition.

"I think we are much closer to real, prac­ti­cal ap­pli­ca­tions of the tech­nol­ogy," Hao Yan, pro­fes­sor of bio­chem­istry at Ari­zona State Univer­sity and a se­nior sci­en­tist on the project, said.

"Com­bi­na­tions of dif­fer­ent ra­tio­nally de­signed nanorobots car­ry­ing var­i­ous agents may help to ac­com­plish the ul­ti­mate goal of can­cer re­search: the erad­i­ca­tion of solid tu­mours and vas­cu­larised metas­tases [sec­ondary tu­mours hooked up to the blood­stream]."

For more than a decade, bio­engi­neers have been build­ing sim­ple au­tom­ata such as probes, walk­ers and mo­tors out of DNA, which can be pro­grammed with in­struc­tions like a crude bi­o­log­i­cal com­puter.

Yan and his col­leagues at the Chi­nese Academy of Sci­ences in Bei­jing have taken the idea a step fur­ther. Their nanorobots are "origami" sheets of DNA that roll up into tubes around a chem­i­cal pay­load. The tubes are tipped with "fas­ten­ers" that recog­nise and latch on to a chem­i­cal called nu­cle­olin, which is abun­dant on the blood ves­sels that feed can­cers but fairly rare on healthy tis­sue.

When they ar­rive at their desti­na­tion they re­lease their cargo, an en­zyme known as throm­bin, which prompts a blood clot and ef­fec­tively stran­gles the tu­mour’s sup­ply lines.

When the nanorobots were in­jected into the veins of mice with hu­man breast can­cer, the tu­mours typ­i­cally grew to 0.3g, com­pared with three times that weight in mice that were in­jected with salt­wa­ter. The treated mice also sur­vived for 39 days on av­er­age, 10 days longer than the un­treated an­i­mals.

The ther­apy was even more ef­fec­tive in mice with melanoma. It dou­bled sur­vival times and wiped out the tu­mours al­to­gether in three out of eight mice. It also ap­peared to pre­vent the can­cers from spread­ing.

Jus­tine Al­ford, of Can­cer Re­search UK, said DNA nanorobots could al­low for more tar­geted treat­ment, re­duc­ing side ef­fects, but blood-clot­ting drugs were un­likely to be the best use for the tech­nol­ogy.

The study is pub­lished in Na­ture Biotech­nol­ogy.

Shoes must be joy­ful and com­fort­able and they don’t have to be ex­pen­sive.

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