Mammary stem cells have myoepithelial cell properties

Area of Science:

• Cell Biology
• Developmental Biology
• Stem Cell Research

Background:

• Myoepithelial cells form the basal layer of the mammary epithelium.
• They are traditionally considered differentiated cells with limited proliferative potential.

Purpose of the Study:

• To investigate the stem cell potential of mammary gland basal myoepithelial cells.
• To determine if myoepithelial cells can form colonies and repopulate mammary tissue.

Main Methods:

• Disrupting actin-myosin interactions to assess colony formation from single basal cells.
• Flow-sorting myoepithelial cells using specific reporter strategies.
• In vivo transplantation of single-cell-derived colonies to assess mammary repopulating unit (MRU) capacity.
• Inducible lineage tracing of α-smooth muscle actin-expressing myoepithelial cell progeny.

Main Results:

• Up to 54% of single basal cells formed colonies under specific culture conditions.
• An average of 65% of these colonies could repopulate a mammary gland in vivo.
• Flow-sorted myoepithelial cells demonstrated MRU capacity.
• Lineage tracing revealed that myoepithelial cell progeny function as long-lived, lineage-restricted stem cells.

Conclusions:

• A substantial proportion of basal myoepithelial cells possess stem cell properties.
• Myoepithelial cells are key progenitors capable of mammary gland regeneration.
• These cells function as long-lived stem cells throughout reproductive states.