A genome editing tool developed by a mainland scientist and hailed as a breakthrough may have simply been suppressing genetic expression, rather than fundamentally altering DNA, a new study suggests.
The controversial technology, known as NgAgo, came from a poorly funded research team led by biologist Dr Han Chunyu at the Hebei University of Science and Technology. It appeared to offer an easier, more accurate way to alter genes than the current reigning tool, known as Crispr/Cas9. But difficulty in replicating Han’s findings cast doubt on whether the technology was as promising as thought.
A new study by life scientist Dr Liu Dong with Nantong University in Jiangsu province adds to the scepticism. Liu said his team used Han’s tools to make the eyes of a zebrafish smaller, but the method only “knocked” down certain genes, or suppressed their expression. It did not alter the physical structure of its DNA. The paper, published online in Cell Research on Friday, is the first in a peer-reviewed journal to challenge NgAgo’s promise.
Han’s study was hailed as one of the most important made by a mainland scientist, but it came under fire by researchers at home and abroad, who spent enormous money and time trying to repeat it without success.
Life scientists have used DNA knockdown for decades to alter the traits of a species. But in recent years, biologists have found a way to edit the basic structure of DNA sequences.
The most popular method is Crispr/Cas9, which is the subject of an intense lawsuit for billions of dollars involving the technology’s inventors due to its potential value in solving fundamental problems such as cancer and ageing.
Han’s team claimed in their paper, published in Nature Biotechnology in May, NgAgo technology could effectively manipulate the DNA of human genes by applying a mechanism used by ancient bacteria to attack foreign genes.
Han was hailed as a national hero because the technology appeared to promise to overtake Crispr/Cas9, given its apparent unprecedented accuracy and ease of use. He was quickly appointed vice-chairman of a provincial science and technology association and his university received more than 200 million yuan (HK$228 million) in funding from provincial authorities to build an NgAgo centre.
But Liu’s study shows Han’s method does not work, at least on zebrafish. Liu cautioned their experiment did not replicate the human cell experiment described in Han’s paper.
Han once said he would respond to challenges raised to his method on an academic platform. But he has not returned inquiries seeking comment from the South China Morning Post.
Article source: http://www.scmp.com/news/china/article/2045285/study-casts-fresh-doubt-over-mainland-scientists-dna-editing-claim