Concerns were brought to our attention by the readership of the journal that one or more of the images in this article may have been duplicated. This has raised questions regarding the validity of the data. In line with Committee on Publication Ethics (COPE) guidelines and Elsevier's policies, the editors have referred to the authors' Institute for independent investigation.
This Expression of Concern will remain appended to the article until the Institution provides an actionable update or the editorial investigation has been completed.