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Int J Clin Exp Pathol 2013;6(12):2813-2823

Original Article
TLR2-deficiency of cKit+ bone marrow cells is associated with augmented potency to
stimulate angiogenic processes

Nana-Maria Wagner, Laura Bierhansl, Antje Butschkau, Gabriele Noeldge-Schomburg, Jan Patrick Roesner, Brigitte Vollmar

Clinic for Anesthesiology and Critical Care Medicine, University Hospital Rostock, Rostock, Germany; Institute for Experimental Surgery,
University Hospital Rostock, Rostock, Germany

Received September 11, 2013; Accepted October 21, 2013; Epub November 15, 2013; Published December 1, 2013

Abstract: Objective: Toll-like receptor 2 (TLR2)-deficiency is associated with the preservation of vascular function and TLR2-deficient (TLR2-/-)
mice exhibit increased neovascularization following induction of hindlimb ischemia. Hematopoietic stem cells play an important role in
ischemia-induced angiogenesis and we now investigated whether the effects observed in TLR2-/- mice may be attributed to TLR2 deficiency
on bone marrow-derived stem cells. Approach and Results: cKit-positive (cKit+) bone marrow cells (BMC) were isolated from wild type (WT)
and TLR2-/- mice employing MACS-bead technology. Co-incubation of TLR2-/-cKit+ BMC with mature endothelial cells (ECs) resulted in
increased tube formation of ECs on matrigel, augmented sprouting in a 3D-collagen matrix and increased migratory capacity compared to
co-incubation with WT cKit+ BMC. In an in vivo matrigel plug assay, TLR2-/-cKit+ BMC exhibited enhanced formation of capillary-like networks.
In a murine model of hindlimb ischemia, administration of TLR2-/- cKit+ BMC to WT mice augmented capillary density and reperfusion of
ischemic M. gastrocnemius muscle tissue to the level of TLR2-/- mice. Western Blot analysis revealed comparable expression of CXCR4 on
TLR2-/-cKit+ BMC but increased activation of the PI3K downstream signaling molecule protein kinase B (PKB/AKT) compared to WT cKit+ cells.
Conclusions: The absence of TLR2 on cKit+ BMC is associated with augmented potency to support angiogenic processes in vitro and in vivo.
Functional inhibition of TLR2 may therefore provide a novel tool to enhance stem cell function for the treatment of vascular diseases.

Keywords: TLR2, cKit, hematopoietic stem cells, angiogenesis, ischemia

Address correspondence to: Dr. Nana-Maria Wagner, Clinic for Anesthesiology and Critical Care Medicine, University Hospital Rostock,
Schillingallee 35, D-18057 Rostock, Germany. Tel: +49 381 494 6401; Fax: +49 381 494 6402; E-mail: