Objective:To delve into the impact of various growth factors and small molecule components on the growth of mouse mammary epithelial organoids,and to establish a tumor protein 53(TP53)knockout(KO)mouse mammary epithelial organoid model for disease research.Methods:The effect of various culture media(B1-B12),each containing distinct growth factors and small molecule components,on the growth of organoids derived from primary mammary epithelial cells were prepared.The number and size of mammary epithelial organoids were observed and documented through optical microscopy,while their proliferative capacity was assessed using the CCK-8 assay.Subsequently,a TP53 KO mammary epithelial organoid model was established using TP53 conditional KO mice.The difference in the growth and phenotypic characteristics of TP53 wild-type(WT)and TP53 KO organoids were recorded and compared.Results:Noggin-mediated Wnt/β-catenin signaling pathway and bone morphogenetic protein(BMP)signaling pathway were identified crucial for the formation of mammary epithelial organoids.Compared with other media(B1-B6),the complete medium B11 demonstrated better capability in facilitating organoid formation and maintaining the heterogeneity of mammary epithelial cells consistently.In contrast,mammary gland organoids cultured in B12 medium predominantly differentiated into basal-type mammary epithelial cells,possibly due to the addition of Wnt-3a.TP53 KO organoids cultured in B11 medium exhibited a faster growth rate and larger size compared to TP53 WT organoids.Conclusion:The B11 medium can reliably establish an in vitro organoid model of mammary epithelium with the capability of serial passage.Wnt-3a appears to play a crucial role in the formation of basal-type mammary epithelial organoids.

Objective:To delve into the impact of various growth factors and small molecule components on the growth of mouse mammary epithelial organoids,and to establish a tumor protein 53(TP53)knockout(KO)mouse mammary epithelial organoid model for disease research.Methods:The effect of various culture media(B1-B12),each containing distinct growth factors and small molecule components,on the growth of organoids derived from primary mammary epithelial cells were prepared.The number and size of mammary epithelial organoids were observed and documented through optical microscopy,while their proliferative capacity was assessed using the CCK-8 assay.Subsequently,a TP53 KO mammary epithelial organoid model was established using TP53 conditional KO mice.The difference in the growth and phenotypic characteristics of TP53 wild-type(WT)and TP53 KO organoids were recorded and compared.Results:Noggin-mediated Wnt/β-catenin signaling pathway and bone morphogenetic protein(BMP)signaling pathway were identified crucial for the formation of mammary epithelial organoids.Compared with other media(B1-B6),the complete medium B11 demonstrated better capability in facilitating organoid formation and maintaining the heterogeneity of mammary epithelial cells consistently.In contrast,mammary gland organoids cultured in B12 medium predominantly differentiated into basal-type mammary epithelial cells,possibly due to the addition of Wnt-3a.TP53 KO organoids cultured in B11 medium exhibited a faster growth rate and larger size compared to TP53 WT organoids.Conclusion:The B11 medium can reliably establish an in vitro organoid model of mammary epithelium with the capability of serial passage.Wnt-3a appears to play a crucial role in the formation of basal-type mammary epithelial organoids.