In vitro induction of mammary-like differentiation from human pluripotent stem cells

A method of generating mammary cell organoids, comprising:

• culturing human induced pluripotent stem cells (hiPSCs) in a serum-free culture medium enriching non-neural ectoderm cells, the serum-free culture medium comprising a basal medium, proliferation supplements, heparin, and hydrocortisone for the culture of non-neural ectoderm cell-containing mammospheres, for about 8-12 days to generate embryoid bodies (EBs) expressing non-neural ectoderm stem cell markers AP-2γ, CK8 and CK18, wherein the EBs do not express neural ectoderm stem cell markers OTX and SOX11;
• and
• differentiating the EBs into mammary cell organoids comprising breast cells, luminal cells, and basal cells by culturing in a differentiation medium comprising one or more substrates and supplemented with pTHrP from day 1 to day 5, followed by culturing in the differentiation medium supplemented with hydrocortisone, insulin, FGF10, and HGF for 3D culture for about 23-27 days, the differentiation medium being a serum-free culture medium for the culture of mammary luminal and myoepithelial cells,
• wherein the one or more substrates comprise Collagen I, solubilized basement membrane matrix secreted by Engelbreth-Holm-Swarm (EHS) mouse sarcoma cells, or both.

A method of generating mammary cells, comprising:

• culturing human induced pluripotent stem cells (hiPSCs) in a serum-free culture medium enriching non-neural ectoderm cells, the serum-free culture medium comprising a basal medium, proliferation supplements, heparin, and hydrocortisone for the culture of non-neural ectoderm cell-containing mammospheres, for about 8-12 days to generate embryoid bodies (EBs) expressing non-neural ectoderm stem cell markers AP-2γ, CK8 and CK18, wherein the EBs do not express neural ectoderm stem cell markers OTX and SOX11;
• differentiating the EBs into mammary cells comprising breast cells, luminal cells, and basal cells by culturing in a differentiation medium comprising hydrocortisone, insulin, FGF10, and HGF for 3D culture for about 28-32 days, wherein the EBs are cultured in the presence of pTHrP at a concentration of about 50 ng/ml-150 ng/ml from day 1 to day 5, the differentiation medium being a serum-free culture medium for the culture of mammary luminal and myoepithelial cells;
• and
• differentiating the mammary cells to induce formation of the lactogenic mammary cells comprising culturing the mammary cells in the presence of insulin, prolactin and/or hydrocortisone.