Experiments in Japan had hailed earlier this year as a "game-changer" in the quest to grow transplant tissue, amid claims evidence was faked. However, these could not be replicated by researchers, a report said Wednesday.
In a scandal that rocked Japan's scientific establishment, Riken -- a research institute that sponsored the study -- launched an independent experiment in April to verify research published by scientist Haruko Obokata and her colleagues earlier this year.
But the struggle to replicate the experiment casts further doubt on the existence of stem cell-like cells, what the researchers called Stimulus-Triggered Acquisition of Pluripotency (STAP) cells, Japan's Nikkei daily reported.
Obokata was feted after unveiling findings that appeared to show a straightforward way to re-programme adult cells to become stem cells -- precursors that are capable of developing into any other cell in the human body.
Identifying a readily manufacturable supply of stem cells could one day help meet a need for transplant tissues, or even whole organs, meaning that any advance in the field is met with excitement in the scientific community.
But after being accused of fabricating results, she agreed to retract papers published in the respected journal Nature.
Earlier this month, Obokata's co-author, stemcell scientist Yoshiki Sasai, hanged himself.
Researchers have been trying to replicate results appearing to show that exposing ordinary cells to various stresses had made them pluripotent, or able to differentiate into any type of tissue.
Riken had planned to implant these cells into mouse embryos to test whether they really were pluripotent.
But the experiments have been fraught with difficulty from the outset, with researchers unable to reproduce such cells, the Nikkei said, citing unnamed sources.
Obokata has been trying in tandem to reproduce her own results since July, but the existence of the STAP cells at this point looks highly doubtful, the Nikkei said.
Riken is to release an interim report on the follow-up study and announce a shake-up of the developmental biology centre in a Wednesday news conference, where it is expected to slash its staff of around 400 researchers by half.