Matrix compositions and the development of breast acini and ducts in 3D cultures

Breast epithelial cells develop into polarized and highly organized acinar and ductal structures in response to stromal cues, including extracellular matrix composition and density, which can in part be reproduced in 3D culture conditions. Here, we present the effects of various 3D in vitro stroma compositions (termed “matrices” or “substrates”) on the ability of heterotypic cultures of epithelial and mesenchymal stem cells to organize into acinar and tubular structures. Normal murine mammary gland (NMuMG) cells were cultured, either alone or in combination (30:70) with mouse mesenchymal stem cells (D1), in 3D matrices generated by agarose, collagen, and Matrigel® alone or by a combination thereof. After 3–5 d in culture, cell distribution, organization, and the presence of acinus-like and tubule-like structures were determined. The number of acinar structures was significantly higher in cultures grown in combination matrices of agarose with Matrigel® or collagen I when compared with cultures grown in Matrigel® or collagen I alone (p?p?