National Science Foundation East Asia and Pacific Summer Institutes

Joshua (Chuck) Harrell-Lymphatic Vessels

Lymphatic vessels (LV) have long been known to play critical roles in normal physiology and development as well as in the progression of cancers. However, our understanding of the factors that regulate their development and function is limited. Recently proteins that distinguish LVs from blood vessels have been identified. These markers will allow us to begin more in depth studies to understand the factors that regulate their development and function in normal and disease processes. At this point virtually nothing is known about the role of hormones or hormone regulated genes in LV development in hormone dependent organs or cancers. In addition, mapping the development of the lymphatic system in the mammary gland and the ovary has yet to be fully accomplished. My project was to characterise the mammary glands and ovaries from estrogen receptor knockout mice compared to normal mice to determine if loss of estrogen signalling resulted in diminished lymphatic vessel development. A second goal was to determine if a hormone regulated protease ADAMTS1 was differentially expressed in an experimental model that generated breast tumors compared to their lymph node metastases.

By immunohistochemical analysis we aimed to determine if loss of estrogen receptor alpha or beta contributed to a loss of lymphatic vessel development in mammary glands, ovaries or uteri. With this approach it was evident that there was no obvious difference in uterus lymphatic vessel development in mice that do not have functional estrogen receptors. During my research it became apparent that we needed to develop a new method of detecting lymphatic vessels in whole mammary gland. Since immunohistochemistry uses only 5 micron-thick tissues sections, it is hard to assess lymphatic density in tissues that may be 500 microns thick. Therefore we adapted our current protocol and attempted to do whole mammary gland lymphatic vessel staining. Using the mouse ear as a reference (Figure 1) for what lymphatics look like in a whole tissue, we were able to detect lymphatics in immature mammary glands using this approach. We conclude that there are few lymphatic vessels in an immature mouse mammary gland. A second set of experiments quantitatively assessed the amount of LV development in mammary glands and ovaries lacking ER alpha or ER beta by using reverse transcriptase polymerase chain reaction.  By inducing ovulation with PMSG we could assess lymphatic remodeling by PCRing for LYVE and lymphatic specific gene (Figure 2).  These data provide the first evidence that ER alpha, not ER beta, is required for post-ovulatory lymphatic vessel remodeling.

Last Updated: September 01, 2010 05:07 PM

 

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