he existence of very small embryonic-like stem cells (VSELs) has been hotly debated by scientists since they were first reported in mouse bone marrow in 2005. The cells were later identified in human blood and bone marrow as well, and have been proposed as a viable alternative to mouse and human embryonic stem cells (ESCs) in research and medicine. But a study published today (July 24) in Stem Cell Reports has called the very existence of VSELs in question, with the senior author deeming them a “distraction.”