Stem Cells International

Review Article

Stem Cells and Cellular Origins of Mammary Gland: Updates in Rationale, Controversies, and Cancer Relevance

Table 1

Markers used to identify MaSCs in different studies.


Study	MSC markers by FACS	Markers’ annotations	Gland reconstitution donor	MRU frequency/gland outgrowth frequency

Stingl et al. [21]	CD45⁻Ter119⁻CD31⁻ CD140a⁻CD24^medCD49f^hi	CD45⁻ and Ter119⁻: to exclude the haematopoietic cells CD31⁻: to exclude the endothelial cells CD140a⁻: to exclude the stromal cells CD24: heat-stable antigen, expressed by the apical plasma membrane of the luminal cells CD49f: α6-integrin, expressed by epidermal stem cells and human mammary colony forming cells	8-14-week-old virgin FVB, C57Bl/6 mice (in 2%FBS)	1 per 60 CD24^medCD49f^hi (from FVB mice) 1 per 90 CD24^medCD49f^hi (from C57Bl/6 mice)

Shackleton et al. [16]	CD45⁻CD31⁻TER119⁻ (Lin⁻) CD24⁺CD29^hi	CD24: heat-stable antigen, also expressed by neural stem cells and human breast cancer cells CD29: β1-integrin, expressed in skin stem cells	8-week-old Rosa-26 mice (with LacZ transgene) (in 50% FBS)	1 per 64 Lin⁻CD24⁺CD29^hi

Badders et al. [22]	CD45⁻CD31⁻Lrp5⁺	Lrp5: Wnt coreceptor, required for mammary ductal stem cell activity and Wnt1-induced tumorigenesis	10-week-old virgin BALB/c mice (in Matrigel)	1 per 485 Lrp5^hi 1 per 142 CD24⁺CD29^hi

Zeng and Nusse [23]	CD31⁻CD45⁻Ter119⁻ CD24⁺CD29^hiAxin2⁺	Axin2: Wnt/β-catenin target gene in canonical Wnt signal transduction pathway	8-12-week-old Axin2-lacZ reporter mice (in 50% Matrigel or 50% serum)	3 per 5 glands Lin⁻CD24⁺CD29^hiAxin2⁺ (from 500 cells) with serum 1 per 5 gland Lin⁻CD24⁺CD29^hiAxin2⁺ (from 100 cells) with serum 6 per 8 glands Lin⁻CD24⁺CD29^hiAxin2⁺ (from 100 cells) with Matrigel 11 per 16 glands Lin⁻CD24⁺CD29^hiAxin2⁺ (from 50 cells) with Matrigel

Spike et al. [24]	CD31⁻CD45⁻Ter119⁻ CD24^medCD49f^hi		Fetal (E18.5) or adult CD1 mice (with/without Matrigel)	1 per 14 fetal CD24^hiCD49f^hi with Matrigel 1 per 50 adult CD24^med CD49f^hi with Matrigel

Plaks et al. [27]	CD31⁻CD45⁻Ter119⁻(Lin⁻) CD24⁺CD49f^hiCK14⁺Lgr5⁺	Lgr5: a downstream target of Wnt and a major stem cell marker in the small intestine, colon, stomach, hair follicle, and kidney nephrons CK14: a major marker of mammary myoepithelial/basal cells	7-9-week-old Lgr5-EGFP pubertal mice (in Matrigel with FGF2)	3 per 9 glands Lin⁻CD24⁺CD49f^hiCK14⁺Lgr5⁺ (from 100 cells) 2 per 12 glands Lin⁻CD24⁺CD49f^hiCK14⁺Lgr5⁺ (from 50 cells) 5 per 16 glands Lin⁻CD24⁺CD49f^hiCK14⁺Lgr5⁺ (from 10 cells)

Machado et al. [26]	Lin⁻CD24⁺CD29^hi large (>10 μm diameter)		8-12-week-old FVB.Cg-Tg(CAG-EGFP)B5Nagy/J female mice (in Matrigel)	1 per 66 Lin⁻CD24⁺CD29^hi, >10 μm diameter 1 per 132 Lin⁻CD24⁺CD29^hi 1 per 237 Lin⁻, >10 μm diameter

dos Santos et al. [25]	CD31⁻CD45⁻Ter119⁻(Lin⁻) CD24⁺CD29^hiCD49f^hiCD1d⁺	CD1d: a glycoprotein expressed on the surface of various mouse and human antigen-presenting cells	6-10-week-old H2b-GFP transgenic virgin mice (in 50% Matrigel)	1 per 8 Lin⁻CD24⁺CD29^hiCD1d⁺1 per 44 Lin⁻CD24⁺CD29^hi

Prater et al. [28]	CD31⁻CD45⁻Ter119⁻ CD49f^hiEpCAM^hiαSMA⁺or Myh11⁺	EpCAM: epithelial cell adhesion molecule; αSMA and Myh11 are functional markers of myoepithelial cells and enhance contractile force generation during lactation	10-14-week-old C57BL/6J, Acta2–GFP and Myh11–Cre–GFP;Rosa26LacZ virgin mice (in 25% Matrigel)	1 per 57 Basal EpCAM^hi 1 per 93 Basal αSMA^hi 1 per 67 Basal Myh11⁺

Wang et al. [29]	Lin⁻CD24⁺CD29^hiProcr⁺	Procr: a novel Wnt target, a protein C receptor, functions in anticoagulation, inflammation, and haematopoiesis	8-week-old CD1 mice (in 50% Matrigel and 20% FBS)	1 per 68 CD24⁺ CD29^hi 1 per 12 CD24⁺ CD29^hiProcr⁺

Zeng et al. [31]	Lin⁻CD24⁺CD29⁺Ccnys⁻ lost the basal stem cell function in regeneration	Ccnys: Ccny and paralogue Ccnyl1, essential in Wnt signaling activity for maintaining the developmental potential of dividing MSCs; expression of Ccnyl1 and Axin2 overlapped in pubertal mammary gland	8-12-week-old transgenic mice (in 50% Matrigel and 20% FBS)	1 per 5024 Ccny^+/−; Ccnyl1^+/lacZ + scramble-shRNA (loss of 2 copies) 1 per 13355 Ccny^−/−; Ccnyl1^+/lacZ + scramble-shRNA (loss of 3 copies) None Ccny^−/−; Ccnyl1^+/lacZ + Ccnyl1-shRNA (Ccnys depleted)

MRU: mammary repopulating unit; CD45: protein tyrosine phosphatase receptor type C; Ter119: lymphocyte antigen 76; CD31: platelet/endothelial cell adhesion molecule 1; CD140: platelet-derived growth factor receptor; CD49f: α6-integrin; CD29: β1-integrin; Lrp5: LDL receptor-related protein 5; Lgr5: leucine-rich repeat-containing G protein-coupled receptor 5; EpCAM: epithelial cell adhesion molecule; α-SMA: alpha smooth muscle actin; Myh11: smooth muscle myosin, heavy polypeptide 11.