Induction of Microvascular Network Growth in the Mouse Mesentery
Authors: Suarez‐Martinez Ariana Diandra , Peirce‐Cottler Shayn M. , Isakson Brant , Scallan Joshua , Murfee Walter Lee 
Published: June 2021

Ex Vivo biomimetic models have emerged as powerful experimental tools for basic science discovery and pre‐clinical drug testing. A challenge for microvascular research is recapitulating the complexity associated with intact networks in real tissue scenarios. To meet this challenge, our laboratory recently introduced the rat mesentery culture model, which enables the real‐time investigation of multicellular interactions during angiogenesis and lymphangiogenesis at the same time. The impact of this approach could be increased with the use of analogous transgenic mouse tissue. However, mouse mesentery is normally avascular raising the question: Can we induce microvascular growth into the mouse mesentery? Preliminary observations of mesenteric tissues harvested from mice treated with tamoxifen for conditional knockout studies suggests that vascularization in the mouse mesentery might be possible. The objective of this study was to test the hypothesis that tamoxifen treatment causes microvascular growth into avascular mouse mesenteric tissue. Female C57BL/6 mice were given a daily IP injection of 0.1 mL for 5 consecutive days containing the following experimental groups: Saline, Sunflower Seed Oil (Oil), and Tamoxifen (Tmx) dissolved in sunflower seed oil (10 mg/mL). Following 21 days post the last injection, mesenteric tissues were harvested and labeled with anti‐mouse platelet endothelial cell adhesion molecule (PECAM), neuron‐glial antigen 2 (NG2), and alpha‐smooth muscle actin (a‐SMA) antibodies to identify endothelial cells, pericytes, and smooth muscle cells, respectively. Zero tissues (0/8) from the Saline group contained a branching microvascular network. In contrast, all tissues from the Oil (8/8) and Tmx (8/8) groups contained networks with arterioles, venules, and capillaries. Smooth muscle cells and pericytes were present in their expected wrapping morphologies and locations along the hierarchy of the networks. In contrast to Saline tissues, Oil and Tmx treated tissues also contained branching LYVE‐positive lymphatic networks. The dramatic increase of vascularized tissue area and the vascularized tissue density were not significantly different between the Oil and Tmx groups (vascular area: Saline = 0.05 ± 0.05 %, Oil = 28.34 ± 8.61 %, Tmx = 35.56 ± 9.47 %; vascular density: Saline = 4.19 ± 4.19 #/mm2, Oil = 290.26 ± 32.00 #/mm2, Tmx = 275.61 ± 31.82 #/mm2; n = 8 tissues from 2 mice per group). The results of this study provide the first evidence that microvascular network growth in mouse mesenteric tissues can be induced and that sunflower seed oil is sufficient for the stimulation. More importantly, the results enable the use of mesentery tissue culture for the novel investigation of microvascular cell dynamics with transgenic mouse strains.Support or Funding InformationNIH R01AG049821This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.