title: Characterization of lymphangiogenesis in a model of adult skin regeneration.
abstract: To date, adult lymphangiogenesis is not well understood. In this study we describe the evolution of lymphatic capillaries in regenerating skin and correlate lymphatic migration and organization with the expression of matrix metalloproteinases (MMPs), immune cells, the growth factors VEGF-A and VEGF-C, and the heparan sulfate proteogylcan perlecan, a key component of basement membrane. We show that while lymphatic endothelial cells (LECs) migrate and organize unidirectionally, in the direction of interstitial fluid flow, they do not sprout into the region but rather migrate as single cells that later join together into vessels. Furthermore, in a modified "shunted flow" version of the model, infiltrated LECs fail to organize into functional vessels, indicating that interstitial fluid flow is necessary for lymphatic organization. Perlecan expression on new lymphatic vessels was only observed after vessel organization was complete and also appeared first in the distal region, consistent with the directionality of lymphatic migration and organization. VEGF-C expression peaked at the initiation of lymphangiogenesis but was reduced to lower levels throughout organization and maturation. In mice lacking MMP-9, lymphatics regenerated normally, suggesting that MMP-9 is not required for lymphangiogenesis, at least in mouse skin. This study thus characterizes the process of adult lymphangiogenesis and differentiates it from sprouting blood angiogenesis, verifies its dependence on interstitial fluid flow for vessel organization, and correlates its temporal evolution with those of relevant environmental factors.
authors.affiliation: Laboratory for Mechanobiology and Morphogenesis, Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne, Station 15, 1015 Lausanne, Switzerland.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Rutkowski
authors.forename: Kendrick C
authors.initials: KC
authors.lastname: Boardman
authors.forename: Melody A
authors.initials: MA
authors.lastname: Swartz
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000502:physiology; D004729:Endothelium, Lymphatic / Q000166:cytology / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D019812:Heparan Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism; D042583:Lymphangiogenesis / Q000235:genetics / Q000502:physiology*; D042601:Lymphatic Vessels / Q000166:cytology / Q000378:metabolism*; D008264:Macrophages / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D012038:Regeneration / Q000235:genetics / Q000502:physiology*; D012867:Skin / Q000098:blood supply* / Q000378:metabolism; D012879:Skin Physiological Phenomena; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics / Q000378:metabolism
chemical_list: D019812:Heparan Sulfate Proteoglycans; D042461:Vascular Endothelial Growth Factor A; D042582:Vascular Endothelial Growth Factor C; C071927:perlecan; D020780:Matrix Metalloproteinase 9