Table 4.

Characterization and optimization of an in vivo mammary gland morphogenesis model¹.

MEC	Stromal cells	ECM	Outcome
Humanized mammary fat pads
None	hTert MSC	ECM or None	No growth
+	hTert MSC	Col I plus matrigel	Slow growth of xenografts (>10 weeks) and differentiation into striated epithelium
Normal mouse mammary fat pads
+	hTert MSC	Col I plus matrigel	Rapid xenograft growth (≤8 weeks) and differentiation into striated epithelium
+	hTert MSC	None	Low engraftment (3 out 8 animals) and lack of differentiation
+	None	Col I plus matrigel	Small xenografts (<1-2 mm) and lack of differentiation
+	None	Matrigel	Small xenografts (<1-2 mm), but formation of acni and clusters of cells
+	RMF/EG	Matrigel/No ECM	Larger xenografts (>5–10 mm), but outgrowth of fibroblasts
+	hTert MSC	Matrigel	Growth of xenografts (>5 mm) and differentiation epithelial cells
Pregnant mammary fat pads
+	hTert MSC	Matrigel	Growth of xenografts (>5 mm) and formation of lumen

¹+ indicates MCF-7 transfected with CEACAM1-4S.