Some cord blood banks claim that they are saving VSEL cells (very small embryonic like cells) when storing whole blood. Last year a paper was published showing that VSEL cells do not expand in culture and the results suggested that umbilical cord blood VSELs cells are an aberrant and inactive population.
Now in ‘Nature’ doubt has been cast over the existence of these cells. A paper has been published suggesting that the VSEL cells are not real. For more information read here.