Nonvenous origin of dermal lymphatic vasculature.
BACKGROUND
The formation of the blood vasculature is achieved via 2 fundamentally different mechanisms, de novo formation of vessels from endothelial progenitors (vasculogenesis) and sprouting of vessels from pre-existing ones (angiogenesis). In contrast, mammalian lymphatic vasculature is thought to form exclusively by sprouting from embryonic veins (lymphangiogenesis). Alternative nonvenous sources of lymphatic endothelial cells have been suggested in chicken and Xenopus, but it is unclear whether they exist in mammals.


OBJECTIVE
We aimed to clarify the origin of the murine dermal lymphatic vasculature.


RESULTS
We performed lineage tracing experiments and analyzed mutants lacking the Prox1 transcription factor, a master regulator of lymphatic endothelial cell identity, in Tie2 lineage venous-derived lymphatic endothelial cells. We show that, contrary to current dogma, a significant part of the dermal lymphatic vasculature forms independently of sprouting from veins. Although lymphatic vessels of cervical and thoracic skin develop via sprouting from venous-derived lymph sacs, vessels of lumbar and dorsal midline skin form via assembly of non-Tie2-lineage cells into clusters and vessels through a process defined as lymphvasculogenesis.


CONCLUSIONS
Our results demonstrate a significant contribution of nonvenous-derived cells to the dermal lymphatic vasculature. Demonstration of a previously unknown lymphatic endothelial cell progenitor population will now allow further characterization of their origin, identity, and functions during normal lymphatic development and in pathology, as well as their potential therapeutic use for lymphatic regeneration.
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Ines
I
Martinez-Corral
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Maria H
MH
Ulvmar
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Lukas
L
Stanczuk
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Florence
F
Tatin
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Krishnakumar
K
Kizhatil
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Simon W M
SW
John
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Kari
K
Alitalo
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.).
Sagrario
S
Ortega
From the Department of Immunology, Genetics, and Pathology, Uppsala University, Uppsala, Sweden (I.M.-C., M.H.U., L.S., T.M.); Lymphatic Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom (I.M.-C., L.S., F.T., T.M.); Howard Hughes Medical Institute, The Jackson Laboratory, Bar Harbor, ME (K.K., S.W.M.J.); Wihuri Research Institute, Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland (K.A.); Biotechnology Programme, Spanish National Cancer Research Centre, Madrid, Spain (S.O.). taija.makinen@igp.uu.se.
Taija
T
Makinen
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism; D066026:Endothelial Progenitor Cells / Q000166:cytology* / Q000378:metabolism; D004729:Endothelium, Lymphatic / Q000166:cytology* / Q000378:metabolism; D017930:Genes, Reporter; D005865:Gestational Age; D018398:Homeodomain Proteins / Q000235:genetics; D042583:Lymphangiogenesis; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D042787:Receptor, TIE-2 / Q000378:metabolism; D012867:Skin / Q000098:blood supply*; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000235:genetics; D014680:Veins / Q000166:cytology / Q000378:metabolism; D000098551:Prospero-Related Homeobox 1 Protein
D015415:Biomarkers; D018398:Homeodomain Proteins; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein; D042787:Receptor, TIE-2; C079086:Tek protein, mouse; D040321:Vascular Endothelial Growth Factor Receptor-3
developmental biology; endothelial cells; endothelial progenitor cells; lymphangiogenesis; lymphatic vessels