THEY were hailed as an 鈥渆thical鈥� alternative to embryonic stem cells 鈥� adult stem cells that can turn into any of the body鈥檚 tissues. Doubts have grown, but now a prominent sceptic has shown that one claim seems to be true: they form all the cell types found in blood.
Catherine Verfaillie of the University of Minnesota in Minneapolis demonstrated the existence of multipotent adult progenitor cells (MAPCs) in 2002. Isolated from bone marrow, they belong to a class of stem cells that normally form muscle and bone. MAPCs seemed to be much more versatile, however (New 杏吧原创, 26 January 2002, p 4).
Other teams struggled to repeat the results. Now Verfaillie has teamed up with Irving Weissman of Stanford University in California, who was sceptical of the initial results. They transplanted MAPCs into mice that had been irradiated, wiping out their haematopoietic stem cells (HSCs) 鈥� another class of marrow cells that give rise to blood. The transplanted MAPCs formed all blood cell types, they found (The Journal of Experimental Medicine, DOI: 10.1084/jem.20061115).
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However, the jury is still out over other claims made for MAPCs. 鈥淚 was disappointed to see that only blood cells were derived,鈥� says Weissman.
