SHORT-LIVED STEM CELLS. “There is general acceptance that mesenchymal cells, cord blood, adipose tissues and other adult stem cell sources often do not survive for more than a few weeks in patients, and their effects are most likely through growth factor release, host inflammatory responses and vascular alterations rather than replacing tissues lost in the disease.”
http://hmg.oxfordjournals.org/content/early/2013/08/19/hmg.ddt379.full