PRS PSRC Podium Proofs 2016
Andrew K. Edwards,* Kyle Glithero,* Alison A. Kitajewski,* Justin E. Kung,* Naikhoba Munabi,* Jan Kitajewski,† Carrie Shawber,*† June K. Wu*
From the *Department of Surgery, Columbia University Medical Center, New York, N.Y.; and †Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, N.Y.
PURPOSE: Infantile hemangiomas (IHs) are vascular tumors of infancy that occur within the first 5 years and proceed through a phase of rapid proliferation followed by involution. IHs are thought to originate from CD133+ hemangioma stem cells (HemSCs). HemSCs are localized in perivascular regions of IH tissue and express NOTCH3, a protein involved in mural cell (vascular smooth muscle cell and pericyte) differentiation and maturation. We hypothesize that NOTCH3 functions in HemSCs to promote mural cell differentiation.
METHODS: Isolated CD133+ HemSCs were infected with lentiviruses encoding a NOTCH3 shRNA (N3KD) or scrambled control (SCR). To evaluate NOTCH3 function in HemSC differentiation in vitro, HemSCs were cultured with cord blood endothelial progenitor cells (cbEPCs), which express high levels of the NOTCH ligand, JAGGED1. To assess the role of HemSC in vivo, a mouse IH model was used in which HemSCs and cbEPCs were suspended in Matrigel and engrafted in immunodeficient mice. IH matrigel implants were harvested for histological analysis after 14 days.
RESULTS: HemSCs differentiated into α-SMA+ cells when cocultured with cbEPCs in vitro. In N3KD HemSCs, α-SMA expression was reduced when compared with control HemSCs. In vivo, Doppler ultrasound revealed vascular structures with blood flow in control HemSC implants. Blood flow was reduced in N3KD HemSCs implants. Histological analysis of control implants revealed ectatic vessels with typical IH morphology supported by α-SMA+ mural cells. In contrast, IH matrigel implants with N3KD HemSCs had decreased α-SMA+ mural cell coverage and poor vessel integrity.
CONCLUSIONS: In IHs, NOTCH3 promotes HemSC differentiation into α-SMA+ perivascular cells that may support pathological IH blood vessel stability, suggesting that NOTCH3 is a potential therapeutic target.