title: Lymphatic/Blood endothelial cell connections at the capillary level in adult rat mesentery.
abstract: Analyses of microvascular networks with traditional tracer filling techniques suggest that the blood and lymphatic systems are distinct without direct communications, yet involvement of common growth factors during angiogenesis and lymphangiogenesis suggest that interactions at the capillary level are possible. To investigate the structural basis for lymphatic/blood endothelial cell connections during normal physiological growth, the objective of this study was to characterize the spatial relations between lymphatic and blood capillaries in adult rat mesenteric tissue. Using immunohistochemical methods, adult male Wistar rat mesenteric tissues were labeled with antibodies against PECAM (an endothelial marker) and LYVE-1, Prox-1, or Podoplanin (lymphatic endothelial markers) or NG2 (a pericyte marker). Positive PECAM labeling identified apparent lymphatic/blood endothelial cell connections at the capillary level characterized by direct contact or direct alignment with one another. In PECAM labeled networks, a subset of the lymphatic and blood capillary blind ends were connected with each other. Intravital imaging of FITC-Albumin injected through the femoral vein did not identify lymphatic vessels. At contact sites, lymphatic endothelial markers did not extend along blood capillary segments. However, PECAM positive lymphatic sprouts, structurally similar to blood capillary sprouts, lacked observable lymphatic marker labeling. These observations suggest that nonlumenal lymphatic/blood endothelial cell interactions exist in unstimulated adult microvascular networks and highlight the potential for lymphatic/blood endothelial cell plasticity.
authors.affiliation: Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118-5698, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Robichaux
authors.forename: Eleanor
authors.initials: E
authors.lastname: Tanno
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Rappleye
authors.forename: Mariana
authors.initials: M
authors.lastname: Ceballos
authors.forename: William B
authors.initials: WB
authors.lastname: Stallcup
authors.forename: Geert W
authors.initials: GW
authors.lastname: Schmid-Schönbein
authors.forename: Walter L
authors.initials: WL
authors.lastname: Murfee
mesh_terms: D000818:Animals; D000941:Antigens / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D004729:Endothelium, Lymphatic / Q000166:cytology* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D020286:Pericytes / Q000166:cytology* / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism; D013152:Splanchnic Circulation / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein; D000099216:Chondroitin Sulfate Proteoglycan 4; D000098853:Podoplanin
chemical_list: D000941:Antigens; D015415:Biomarkers; D018398:Homeodomain Proteins; D008562:Membrane Glycoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011509:Proteoglycans; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D000099216:Chondroitin Sulfate Proteoglycan 4; C533408:Lyve1 protein, rat; C092025:Pdpn protein, rat; D000098853:Podoplanin