Name: isolation of intact, whole mouse mammary glands for analysis of extracellular matrix expression and gland morphology
Uploaded: 2017-10-30T15:00:00
Description: Watch this Scientific Journal Video about Isolation of Intact, Whole Mouse Mammary Glands for Analysis of Extracellular Matrix Expression and Gland Morphology at JoVE.com

The authors would like to acknowledge April Wiles and Dr. Roger Broderson for assistance with animal necropsy and gland isolation, respectively. Funding for this work was supported by the Philadelphia College of Osteopathic Medicine Centers for Chronic Disorders of Aging.

Procedures involving animal subjects in this protocol were reviewed and approved by the Institutional Animal Care and Use Committee of the Philadelphia College of Osteopathic Medicine and all techniques were conducted under strict ethical guidelines.
1. Sample Procurement and Processing
<ol>
	<li>Select appropriate animal subject and place into a CO2 chamber. For this experiment, use 8-10 week old female nulliparous B6.Cg-Cav1tmMIs/J and C57BI/6J.</li>
	<li>Turn on gas flow to 30-...

<ol>
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R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrix+crosslinking+forces+tumor+progression+by+enhancing+integrin+signaling.">Matrix crosslinking forces tumor progression by enhancing integrin signaling.</a> Cell. 139 (5), 891-906 (2009).</li><li>Wang, J. P., Hielscher, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibronectin:+How+Its+Aberrant+Expression+in+Tumors+May+Improve+Therapeutic+Targeting.">Fibronectin: How Its Aberrant Expression in Tumors May Improve Therapeutic Targeting.</a> J Cancer. 8 (4), 674-682 (2017).</li><li>Qian, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prognostic+significance+of+tumor/stromal+caveolin-1+expression+in+breast+cancer+patients.">Prognostic significance of tumor/stromal caveolin-1 expression in breast cancer patients.</a> Cancer Sci. 102 (8), 1590-1596 (2011).</li><li>Simpkins, S. A., Hanby, A. M., Holliday, D. L., Speirs, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+and+functional+significance+of+loss+of+caveolin-1+expression+in+breast+cancer-associated+fibroblasts.">Clinical and functional significance of loss of caveolin-1 expression in breast cancer-associated fibroblasts.</a> J Pathol. 227 (4), 490-498 (2012).</li><li>Witkiewicz, A. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+absence+of+stromal+caveolin-1+expression+predicts+early+tumor+recurrence+and+poor+clinical+outcome+in+human+breast+cancers.">An absence of stromal caveolin-1 expression predicts early tumor recurrence and poor clinical outcome in human breast cancers.</a> Am J Pathol. 174 (6), 2023-2034 (2009).</li><li>Macias, H., Hinck, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammary+gland+development.">Mammary gland development.</a> Wiley Interdiscip Rev Dev Biol. 1 (4), 533-557 (2012).</li><li>Caligioni, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+reproductive+status/stages+in+mice.">Assessing reproductive status/stages in mice.</a> Curr Protoc Neurosci. , (2009).</li><li>Cannata, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elevated+circulating+IGF-I+promotes+mammary+gland+development+and+proliferation.">Elevated circulating IGF-I promotes mammary gland development and proliferation.</a> Endocrinology. 151 (12), 5751-5761 (2010).</li><li>Thompson, C., Rahim, S., Arnold, J., Hielscher, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loss+of+caveolin-1+alters+extracellular+matrix+protein+expression+and+ductal+architecture+in+murine+mammary+glands.">Loss of caveolin-1 alters extracellular matrix protein expression and ductal architecture in murine mammary glands.</a> PLoS One. 12 (2), 0172067 (2017).</li><li>Williams, C. 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In the paper, we have described a technique to isolate intact mouse mammary glands for downstream histological analyses of ECM expression and ductal morphology. With respect to analyses of ductal morphology, this methodology enables the rapid investigation of ductal architecture based off of stained histological sections. Other methods of ductal analyses rely on injections of dyes to enable visualization of the ductal tree, methods which may be technically challenging and time consuming.
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Breast cancer is characterized by a substantial degree of tissue fibrosis1,2,3,4. Referred to as the ECM, this non-cellular entity is found in varying degrees in all tissues and is primarily comprised of a complex meshwork of fibrillar and non-fibrillar collagens, elastin, and glycoproteins in addition to various signaling molecules that are sequestered in this matrix. Under homeostatic conditions, the deposition and degradation of the ECM is tightly controlled.5 During breast tumorigenesis, the balance of ECM deposition and degradation is disrupted. As such, breast tumors have been reported to express abundant ECM proteins such as collagens, fibronectin and tenascin-C amongst others.6 The abnormal expression of these proteins in addition to increased patterns of matrix crosslinking has been documented to promote breast tumor progression, metastasis and therapy resistance1,3,4,7,8,9.
To assess ECM composition and ductal morphology, isolation of intact mammary glands was performed. Here, we used female nulliparous mice deficient for caveolin-1, an integral membrane protein which has been linked to an aggressive breast tumor signature10,11,12, and control female nulliparous B6 mice. Histological processing and staining of these tissues permitted the identification of several ECM proteins along with characterization of ductal morphology.
Overall, the isolation of whole, intact mammary glands gives researchers the opportunity to investigate tissue-wide morphological or cellular changes occurring in response to exogenous or endogenous factors. Drawbacks of the technique are associated with analyses of 2 dimension (2D) tissue sections as opposed to a 3D perspective, which would yield a more complete picture of the complex morphology of the ductal tree. Given the complexity of cell-cell and cell-ECM interactions that take place in the mammary gland, the isolation of whole, intact glands is advantageous for efficiently analyzing ductal morphology and protein expression in various regions of the murine mammary gland.

<table>
	<tbody>
		<tr>
			<td>Light Microscope</td>
			<td>Olympus</td>
			<td>BX43</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Camera</td>
			<td>Olympus</td>
			<td>DP73</td>
			<td></td>
		</tr>
		<tr>
			<td>Image Analysis Software</td>
			<td>Olympus</td>
			<td>cellSens Entry software</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>NIH</td>
			<td>ImageJ</td>
			<td></td>
		</tr>
		<tr>
			<td>3.5x-R Surgical Micro Loupes</td>
			<td>Rose Micro Solutions</td>
			<td></td>
			<td>Magnification at researcher&#39;s preference</td>
		</tr>
		<tr>
			<td>Mayo Scissors</td>
			<td>Medline</td>
			<td>DYND04035</td>
			<td></td>
		</tr>
		<tr>
			<td>Staining Rack</td>
			<td>Fisher Scientific</td>
			<td>121</td>
			<td></td>
		</tr>
		<tr>
			<td>Staining Dish</td>
			<td>Fisher Scientific</td>
			<td>112</td>
			<td></td>
		</tr>
		<tr>
			<td>Coplin Jars</td>
			<td>Fisher Scientific</td>
			<td>19-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass coverslips</td>
			<td>Fisher Scientific</td>
			<td>12-550-15</td>
			<td>Size appropriate for tissue</td>
		</tr>
		<tr>
			<td>IHC EnVision+ Kit (HRP, Mouse, DAB+)</td>
			<td>Dako</td>
			<td>K400611-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Picrosirius Red Kit</td>
			<td>Abcam</td>
			<td>AB150681</td>
			<td></td>
		</tr>
		<tr>
			<td>Eosin Y, alcoholic</td>
			<td>Sigma-Aldrich</td>
			<td>HT110132</td>
			<td></td>
		</tr>
		<tr>
			<td>Harris Hematoxylin</td>
			<td>Sigma-Aldrich</td>
			<td>HHS16</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey Serum</td>
			<td>EMD Millipore</td>
			<td>S30</td>
			<td></td>
		</tr>
		<tr>
			<td>10% Neutral Buffered Formalin</td>
			<td>Sigma-Aldrich</td>
			<td>HT501128</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylenes, Reagent Grade</td>
			<td>Sigma-Aldrich</td>
			<td>214736</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol, 200 proof</td>
			<td>Sigma-Aldrich</td>
			<td>792780</td>
			<td>suitable for molecular biology</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline, 1x</td>
			<td>Gibco</td>
			<td>10010023</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Citrate</td>
			<td>Fisher Scientific</td>
			<td>S279-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium Carbonate</td>
			<td>Sigma-Aldrich</td>
			<td>202932</td>
			<td></td>
		</tr>
		<tr>
			<td>Permanent Mounting Medium</td>
			<td>Dako</td>
			<td>S1964</td>
			<td></td>
		</tr>
		<tr>
			<td>Eukitt&#39;s Mounting Medium</td>
			<td>Sigma-Aldrich</td>
			<td>3989</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibronectin antibody</td>
			<td>Abcam</td>
			<td>AB23750</td>
			<td></td>
		</tr>
		<tr>
			<td>Tenascin-C antibody</td>
			<td>Abcam</td>
			<td>AB108930</td>
			<td></td>
		</tr>
		<tr>
			<td>Alpha Smooth Muscle Actin antibody</td>
			<td>Abcam</td>
			<td>AB124964</td>
			<td></td>
		</tr>
		<tr>
			<td>Dako Envision Dual Link System HRP</td>
			<td>Dako</td>
			<td>K4065</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of intact, whole mouse mammary glands for analysis of extracellular matrix expression and gland morphology

The goal of this procedure was to harvest the #4 abdominal mammary glands from female nulliparous mice in order to assess ECM expression and ductal architecture. Here, a small pocket below the skin was created using Mayo scissors, allowing separation of the glands within the subcutaneous tissue from the underlying peritoneum. Visualization of the glands was aided by the use of 3.5x-R surgical micro loupes. The pelt was inverted and pinned back allowing identification of the intact mammary fat pads. Each of the #4 abdominal glands was bluntly dissected by sliding the scalpel blade laterally between the subcutaneous layer and the glands. Immediately post-harvest, glands were placed in 10% neutral buffered formalin for subsequent tissue processing. Excision of the entire gland is advantageous because it primarily eliminates the risk of excluding important tissue-wide interactions between ductal epithelial cells and other microenvironmental cellular populations that could be missed in a partial biopsy. One drawback of the methodology is the use of serial sections from fixed tissues which limits analyses of ductal morphogenesis and protein expression to discrete locations within the gland. As such, changes in ductal architecture and protein expression in 3 dimensions (3D) is not readily obtainable. Overall, the technique is applicable to studies requiring whole intact murine mammary glands for downstream investigations such as developmental ductal morphogenesis or breast cancer.

Female mice have 5 pairs of mammary glands. Specifically, there is one pair of cervical glands (#1), two pairs of thoracic glands (#2 and #3), one pair of abdominal glands (#4), and 1 pair of inguinal glands (#5) (Figure 1A). Here, we isolated the #4 glands as they are readily identifiable. In some circumstances, both #4 and #5 glands were isolated together as distinction between the two was difficult. To isolate intact #4 abdominal mammary g...

Watch this Scientific Journal Video about Isolation of Intact, Whole Mouse Mammary Glands for Analysis of Extracellular Matrix Expression and Gland Morphology at JoVE.com

Isolation of Intact, Whole Mouse Mammary Glands for Analysis of Extracellular Matrix Expression and Gland Morphology

Here, we present a protocol for the isolation of whole, intact mouse mammary glands to investigate extracellular matrix (ECM) expression and ductal morphology. Mouse #4 abdominal glands were extracted from 8-10 week old female nulliparous mice, fixed in neutral buffered formalin, sectioned and stained using immunohistochemistry for ECM proteins.

The goal of this procedure was to harvest the #4 abdominal mammary glands from female nulliparous mice in order to assess ECM expression and ductal ...

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