NOTCH3 regulates stem-to–mural cell differentiation in infantile hemangioma
Andrew K. Edwards, Kyle Glithero, Peter Grzesik, Alison A. Kitajewski, Naikhoba C.O. Munabi, Krista Hardy, Qian Kun Tan, Michael Schonning, Thaned Kangsamaksin, Jan K. Kitajewski, Carrie J. Shawber, June K. Wu
Andrew K. Edwards, Kyle Glithero, Peter Grzesik, Alison A. Kitajewski, Naikhoba C.O. Munabi, Krista Hardy, Qian Kun Tan, Michael Schonning, Thaned Kangsamaksin, Jan K. Kitajewski, Carrie J. Shawber, June K. Wu
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Research Article Vascular biology

NOTCH3 regulates stem-to–mural cell differentiation in infantile hemangioma

Abstract

Infantile hemangioma (IH) is a vascular tumor that begins with rapid vascular proliferation shortly after birth, followed by vascular involution in early childhood. We have found that NOTCH3, a critical regulator of mural cell differentiation and maturation, is expressed in hemangioma stem cells (HemSCs), suggesting that NOTCH3 may function in HemSC-to–mural cell differentiation and pathological vessel stabilization. Here, we demonstrate that NOTCH3 is expressed in NG2+PDGFRβ+ perivascular HemSCs and CD31+GLUT1+ hemangioma endothelial cells (HemECs) in proliferating IHs and becomes mostly restricted to the αSMA+NG2loPDGFRβlo mural cells in involuting IHs. NOTCH3 knockdown in HemSCs inhibited in vitro mural cell differentiation and perturbed αSMA expression. In a mouse model of IH, NOTCH3 knockdown or systemic expression of the NOTCH3 inhibitor, NOTCH3 Decoy, significantly decreased IH blood flow, vessel caliber, and αSMA+ perivascular cell coverage. Thus, NOTCH3 is necessary for HemSC-to–mural cell differentiation, and adequate perivascular cell coverage of IH vessels is required for IH vessel stability.

Authors

Andrew K. Edwards, Kyle Glithero, Peter Grzesik, Alison A. Kitajewski, Naikhoba C.O. Munabi, Krista Hardy, Qian Kun Tan, Michael Schonning, Thaned Kangsamaksin, Jan K. Kitajewski, Carrie J. Shawber, June K. Wu

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Figure 5

NOTCH3 activity is required for HemSC mural cell differentiation and IH development in a mouse model of IH.

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NOTCH3 activity is required for HemSC mural cell differentiation and IH ...
NOTCH3-knockdown (N3KD) HemSCs or Scr HemSCs in a 1:1 ratio with ECFCs were resuspended in Matrigel, and subcutaneously implanted into the flanks of immunocompromised mice. (A) Detection of high blood flow by ultrasound Doppler in Scr HemSC/ECFC and N3KD HemSC/ECFC xenografts at day 14 after implantation. Xenograft area marked with yellow dotted line. White arrowheads mark Dopplerable blood flow (red). (B) Scatter plot of mean Doppler signal intensity normalized by xenograft area (n = 3 populations: H1, H2, H3; n = 2 implants each). Average mean intensity denoted with a horizontal line. Error bars represent ± SD. *P < 0.03, 1-way ANOVA. (C) H&E staining of Scr HemSC/ECFC and N3KD HemSC/ECFC xenograft sections. Arrowheads mark red blood cell–containing vessels. (D) Quantification of vessel density and caliber (n = 3 populations; n = 2 implants each). Error bars represent ± SD. *P < 0.0002, 1-way ANOVA. (E) Scr HemSC/ECFC and N3KD HemSC/ECFC xenograft sections stained for αSMA. White arrowheads mark vessel surrounded by αSMA+ mural cells. Yellow arrowheads mark vessel surrounded by mural cells that express low levels of αSMA. (F) αSMA+ mural cell density determined as mean mural cell αSMA signal intensity normalized to IH endothelial GLUT1 signal intensity. Average mural cell αSMA expression determined as mean αSMA signal intensity–normalized DAPI+αSMA+ cell number (n = 3 populations; n = 2 implants each). Error bars represent ± SD. n.s., not significant. *P < 0.0002, **P < 0.000005, 1-way ANOVA. Scale bars: 50 μm. αSMA, α smooth muscle actin; ECFC, endothelial colony-forming cell; GLUT1, glucose transporter 1; HemSC, hemangioma stem cell; IH, infantile hemangioma, MC, mural cell; Scr, scrambled.