The researchers found that the vast majority of events matching the estimated size of VSELs actually appeared to be artifacts, such as dead cells and debris. The team tested the remaining “exceedingly rare population” of cells that matched the VSEL profile for pluripotency markers without luck.
“The claims about VSELs were not yet replicated by independent scientists,” said Weissman. “We redid the experiments as they have been described and could not confirm what was claimed.”