Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of ...

Boston Children's Hospital and Harvard Medical School

Stromal-epithelial interactions mediate mammary gland development and the formation and progression of breast cancer. To study these interactions in vitro, the development of defined three-dimensional (3D) models is essential. In the present study, we have successfully developed novel 3D in vitro models that allow the formation of mammary gland structures closely resembling those found in vivo. Cocultures of a human mammary epithelial cell line MCF10A and human mammary fibroblasts obtained from reduction mammoplasties embedded in either a type I collagen or a mixed Matrigel-collagen matrix were carried out for up to 6 weeks. Histological and ultrastructural analysis confirmed the formation of ductal and alveolar structures. The importance of the stromal cells was apparent in both matrices; in the collagen gels the presence of reduction mammoplasty fibroblasts accelerated the initial formation of epithelial structures, and in the mixed Matrigel-collagen gels the presence of those fibroblasts was necessary for the formation of ductal structures. These models provide an excellent system to study tissue organization, epithelial morphogenesis, and breast carcinogenesis.

A novel 3D in vitro culture model to study stromal-epithelial interactions in the mammary gland.

Stromal-epithelial interactions mediate breast development, and the initiation and progression of breast cancer. In the present study, we developed 3-dimensional (3D) in vitro models to study breast cancer tissue organization and the role of the microenvironment in phenotypic determination.

The microenvironment determines the breast cancer cells' phenotype: organization of MCF7 cells in 3D cultures.

Epithelial-mesenchymal interactions during embryogenesis are critical in defining the phenotype of tissues and organs. The initial elongation of the mammary bud represents a central morphological event requiring extensive epithelial-mesenchymal crosstalk. The precise mechanism orchestrating this outgrowth is still unknown and mostly animal models have been relied upon to explore this process. Highly tunable three-dimensional (3D) culture models are a complementary approach to address the question of phenotypic determination. Here, we used a 3D in vitro culture to study the roles of stromal cells and extracellular matrix components during mammary tubulogenesis. Fibroblasts, adipocytes, and type I collagen actively participated in this process, whereas reconstituted basement membrane inhibited tubulogenesis by affecting collagen organization. We conclude that biochemical and biomechanical signals mediate the interaction between cells and matrix components and are necessary to induce tubulogenesis in vitro.

Dual regulation of breast tubulogenesis using extracellular matrix composition and stromal cells.

Here we describe a combined microfluidic-micromagnetic cell separation device that has been developed to isolate, detect and culture circulating tumor cells (CTCs) from whole blood, and demonstrate its utility using blood from mammary cancer-bearing mice. The device was fabricated from polydimethylsiloxane and contains a microfluidic architecture with a main channel and redundant 'double collection' channel lined by two rows of dead-end side chambers for tumor cell collection. The microdevice design was optimized using computational simulation to determine dimensions, magnetic forces and flow rates for cell isolation using epithelial cell adhesion molecule (EpCAM) antibody-coated magnetic microbeads (2.8 Î¼m diameter). Using this device, isolation efficiencies increased in a linear manner and reached efficiencies close to 90% when only 2 to 80 breast cancer cells were spiked into a small volume (1.0 mL) of blood taken from wild type mice. The high sensitivity visualization capabilities of the device also allowed detection of a single cell within one of its dead-end side chambers. When blood was removed from FVB C3(1)-SV40 T-antigen mammary tumor-bearing transgenic mice at different stages of tumor progression, cells isolated in the device using anti-EpCAM-beads and magnetically collected within the dead-end side chambers, also stained positive for pan-cytokeratin-FITC and DAPI, negative for CD45-PerCP, and expressed SV40 large T antigen, thus confirming their identity as CTCs. Using this isolation approach, we detected a time-dependent rise in the number of CTCs in blood of female transgenic mice, with a dramatic increase in the numbers of metastatic tumor cells appearing in the blood after 20 weeks when tumors transition to invasive carcinoma and exhibit increased growth of metastases in this model. Importantly, in contrast to previously described CTC isolation methods, breast tumor cells collected from a small volume of blood removed from a breast tumor-bearing animal remain viable and they can be easily removed from these devices and expanded in culture for additional analytical studies or potential drug sensitivity testing.

A combined micromagnetic-microfluidic device for rapid capture and culture of rare circulating tumor cells.

Interleukin-6 (IL6) has recently been reported to promote insulin secretion in a glucagon-like peptide-1-dependent manner. Herein, the direct effects of IL6 (at various concentrations from 0 to 1000â€Špg/ml) on pancreatic Î²-cell metabolism, AMP-activated protein kinase (AMPK) signaling, insulin secretion, nitrite release, and redox status in a rat clonal Î²-cell line and mouse islets are reported. Chronic insulin secretion (in Î¼g/mg protein per 24 â€Šh) was increased from 128Â·7Â±7Â·3 (no IL6) to 178Â·4Â±7Â·7 (at 100 â€Špg/ml IL6) in clonal Î²-cells and increased significantly in islets incubated in the presence of 5Â·5â€Š mM glucose for 2â€Š h, from 0Â·148 to 0Â·167Â±0Â·003 â€Šng/islet. Pretreatment with IL6 also induced a twofold increase in basal and nutrient-stimulated insulin secretion in subsequent 20â€Šmin static incubations. IL6 enhanced both glutathione (GSH) and glutathione disulphide (GSSG) by nearly 20% without changing intracellular redox status (GSSG/GSH). IL6 dramatically increased iNOS expression (by ca. 100-fold) with an accompanying tenfold rise in nitrite release in clonal Î²-cells. Phosphorylated AMPK levels were elevated approximately twofold in clonal Î²-cells and mouse islet cells. Calmodulin-dependent protein kinase kinase levels (CaMKK), an upstream kinase activator of AMPK, were also increased by 50% after IL6 exposure (in Î²-cells and islets). Our data have demonstrated that IL6 can stimulate Î²-cell-dependent insulin secretion via direct cell-based mechanisms. AMPK, CaMKK (an upstream kinase activator of AMPK), and the synthesis of nitric oxide appear to alter cell metabolism to benefit insulin secretion. In summary, IL6 exerts positive effects on Î²-cell signaling, metabolism, antioxidant status, and insulin secretion.

Physiological concentrations of interleukin-6 directly promote insulin secretion, signal transduction, nitric oxide release, and redox status in a clonal pancreatic Î²-cell line and mouse islets.

Some epithelial cancers can be induced to revert to quiescent differentiated tissue when combined with embryonic mesenchyme; however, the mechanism of this induction is unknown. Here we combine tissue engineering, developmental biology, biochemistry and proteomics approaches to attack this problem. Using a synthetic reconstitution system, we show that co-culture of breast cancer cells with embryonic mesenchyme from early stage (E12.5-13.5) mammary glands decreases tumor cell proliferation while stimulating acinus differentiation, whereas cancer-associated fibroblasts (CAFs) fail to produce these normalizing effects. When insoluble extracellular matrices (ECMs) were isolated from cultured early stage (E12.5-13.5) embryonic mammary mesenchyme cells or E10 tooth mesenchyme and recombined with mammary tumor cells, they were found to be sufficient to induce breast cancer normalization including enhanced expression of estrogen receptor-Î± (ER-Î±). In contrast, ECM from later stage (E14.5) mammary mesenchyme and conditioned medium isolated from mesenchymal cell cultures were ineffective. Importantly, when the inductive ECMs produced by early stage embryonic mammary mesenchyme were scraped from dishes and injected into fast-growing breast tumors in mice, they significantly inhibited cancer expansion. Proteomics analysis of the detergent insoluble ECM material revealed several matrix components that were preferentially expressed in the embryonic ECMs. Analysis of two of these molecules previously implicated in cancer regulation--biglycan and tenascin C--revealed that addition of biglyan can mimic the tumor normalization response, and that siRNA knockdown of its expression in cultured embryonic mesenchyme results in loss of the ECM's inductive activity. These studies confirm that embryonic mesenchyme retains the ability to induce partial breast cancer reversion, and that its inductive capability resides at least in part in the ECM protein biglycan that it produces.

Silva Krause

Vascular Biology Program,
Department of Surgery,
Vascular Biology Program, Department of Surgery

Boston Children's Hospital and Harvard Medical School

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Silva Krause

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Boston Children's Hospital and Harvard Medical School

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Vascular Biology Program,
Department of Surgery,
Vascular Biology Program, Department of Surgery