Reports of tooth grafts in mice have sparked debate.
Scientists in Japan claim to be the first to have grown teeth in the lab that can then be successfully grafted into adult animals. The method, they suggest, could be used to reconstitute a wide variety of organs, including hair follicles, kidneys and livers.
But publication of their research in Nature Methods this week has drawn some scathing criticism. ’It’s a disgrace,’ said Paul Sharpe, professor of craniofacial development at King’s College, London, UK. ’The paper says nothing new,’ he said. ’I wouldn’t have accepted it for any journal, let alone Nature Methods.’
The researchers collected epithelium and mesenchyme cells from the incisors of two-week-old mice and injected them into a drop of collagen. Cells from this so-called ’tooth germ’ were then grafted into the gum of a waiting mouse and a new tooth began to grow.
’A complete tooth structure, showing penetration of nerve fibres, can be successfully developed following the engraftment,’ said Takashi Tsuji, associate professor of biological technology at the Tokyo University of Science in Japan. ’Our method provides a substantial advance in the development of bioengineered organ replacement strategies and regenerative therapies,’ he and his colleagues report.
But, claims Sharpe, the methods they report appeared in two key papers published back in 2004. ’They’ve copied what other people have done.’ He was the senior author on one of these earlier papers, which described the surgical transplantation of a bioengineered tooth into an adult animal. This and other work has not been adequately cited, he argued.
Nature Methods defended their decision to publish. The paper underwent full peer review, said the journal’s senior editor Daniel Evanko. ’It was enthusiastically recommended for publication by experts in the area of organ and tooth development.’
In addition to growing teeth in the lab, the same method also worked for whiskers, suggesting it could even be rolled out to regenerate more complex organs like livers and kidneys. ’The procedure resulted in a robust and seemingly generalizable method for development and transplantation of ectodermal organs.’
The change in method reported by Tsuji’s team is ’admittedly small’, said Evanko, but resulted in a higher efficiency of organ development than in previous studies.
Sharpe is not comforted. ’A minor improvement of a published method is not sufficient to justify publication and certainly not to make such bold conclusions,’ he told Chemistry World. ’I don’t know who the so-called experts in tooth development who reviewed this were, but it was not anyone I know who works on tooth tissue engineering.’
K Nakao et al, 2007, Nat Meth, DOI:10.1038/NMETH1012