Local and Circulating Endothelial Cells Undergo Endothelial to Mesenchymal Transition (EndMT) in Response to Musculoskeletal Injury.
Endothelial-to-mesenchymal transition (EndMT) has been implicated in a variety of aberrant wound healing conditions. However, unambiguous evidence of EndMT has been elusive due to limitations of in vitro experimental designs and animal models. In vitro experiments cannot account for the myriad ligands and cells which regulate differentiation, and in vivo tissue injury models may induce lineage-independent endothelial marker expression in mesenchymal cells. By using an inducible Cre model to mark mesenchymal cells (Scx-creERT/tdTomato + ) prior to injury, we demonstrate that musculoskeletal injury induces expression of CD31, VeCadherin, or Tie2 in mesenchymal cells. VeCadherin and Tie2 were expressed in non-endothelial cells (CD31-) present in marrow from uninjured adult mice, thereby limiting the specificity of these markers in inducible models (e.g. VeCadherin- or Tie2-creERT). However, cell transplantation assays confirmed that endothelial cells (ΔVeCadherin/CD31+/CD45-) isolated from uninjured hindlimb muscle tissue undergo in vivo EndMT when transplanted directly into the wound without intervening cell culture using PDGFRα, Osterix (OSX), SOX9, and Aggrecan (ACAN) as mesenchymal markers. These in vivo findings support EndMT in the presence of myriad ligands and cell types, using cell transplantation assays which can be applied for other pathologies implicated in EndMT including tissue fibrosis and atherosclerosis. Additionally, endothelial cell recruitment and trafficking are potential therapeutic targets to prevent EndMT.
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Shailesh
S
Agarwal
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Shawn
S
Loder
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
David
D
Cholok
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Joshua
J
Peterson
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
John
J
Li
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
David
D
Fireman
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Christopher
C
Breuler
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Hsiao Sung
HS
Hsieh
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Kavitha
K
Ranganathan
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Charles
C
Hwang
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
James
J
Drake
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Shuli
S
Li
Department of Surgery, Stanford University, Stanford, CA 94305, USA.
Charles K
CK
Chan
Department of Surgery, Stanford University, Stanford, CA 94305, USA.
Michael T
MT
Longaker
Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
Benjamin
B
Levi
D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002058:Burns, Electric / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology / Q000637:transplantation; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015870:Gene Expression; D006614:Hindlimb; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D059630:Mesenchymal Stem Cells / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics / Q000378:metabolism; D042787:Receptor, TIE-2 / Q000235:genetics / Q000378:metabolism; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D000076182:Sp7 Transcription Factor / Q000235:genetics / Q000378:metabolism; D058971:Tenotomy; D000097573:Red Fluorescent Protein
D053674:Aggrecans; D015820:Cadherins; D017493:Leukocyte Common Antigens; D008164:Luminescent Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D020796:Receptor, Platelet-Derived Growth Factor alpha; D042787:Receptor, TIE-2; D055758:SOX9 Transcription Factor; D000076182:Sp7 Transcription Factor; D000097573:Red Fluorescent Protein; C527933:Sox9 protein, mouse; C479466:Sp7 protein, mouse; C079086:Tek protein, mouse; C516770:Ptprc protein, mouse