Stem cells ensure the development of tissues, their daily maintenance and their repair following injuries. One of the key questions in the field of stem cell biology is to define the different cell lineages in which stem cells can differentiate into.

Stem cells can be multipotent, meaning they present the ability to give rise to more than one lineage, or unipotent, meaning they can only differentiate into one cell lineage. Lineage tracing experiments are routinely used in the fields of developmental and stem cell biology to assess the fate of stem cells in vivo. However, no rigorous method has yet been established to interpret with great precision and statistical confidence the issue of multipotency versus unipotency in lineage tracing experiments.

In a study that makes the cover of the current issue of Genes & Development, researchers developed new methods to assess with great precision the multipotent or unipotent fate of mammary gland and prostate stem cells.

They developed a novel bio-statistical framework to define multipotency with high confidence in multicolor lineage tracing experiments. They developed another method called lineage tracing at saturation to assess the fate of all stem cells in a given tissue and the flux of cells between different lineages. "It was really important to sort out the issue of multipotency of mammary and prostate stem cells in a definitive manner.

These novel and powerful tools combining multicolor lineage tracing, bio-statistical analysis and lineage tracing at saturation will allow to interpret the lineage experiments with much greater confidence", comments the first author of this study.

These new findings unambiguously demonstrate that, while the prostate develops from multipotent stem cells, only unipotent stem cells mediate mammary gland development and adult tissue remodeling. "These methods offer a rigorous framework to assess the lineage relationship and stem cell fate in different organs and tissues.

These techniques will become the new standard to decipher the lineage relationship in many other organs or tissues during development, tissue repair and tumor initiation." comments the senior author.

http://genesdev.cshlp.org/content/early/2016/06/06/gad.280057.116.abstract?sid=4752f580-febd-4932-a356-02784e99721d