Circulating CXCR4-positive stem/progenitor cells compete for SDF-1-positive niches in bone marrow, muscle and neural tissues: an alternative hypothesis to stem cell plasticity.

The trans-differentiation hypothesis of adult tissue-specific stem cells has been recently questioned because of insufficient proof that the so-called plasticity experiments were performed on pure populations of tissue-specific stem cells. It was shown recently, for example, that the formation of haematopoietic colonies by muscle cells depended on the… (More)