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THE STEM CELL NICHE

Rho Inhibition Induces Migration of Mesenchymal Stromal Cells

^aInstitute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, Frankfurt am Main, Germany;
^bChemotherapeutic Research Institute Georg Speyer Haus, Frankfurt, Germany

Key Words. Rho GTPases • Actin • Chemotaxis • Migration • Mesenchymal stem cells

Correspondence: Reinhard Henschler, M.D., Institute of Transfusion Medicine and Immune Hematology, University Hospital Frankfurt, Sandhofstrasse 1, D 60528 Frankfurt, Germany. Telephone: +49 69 6782 191; Fax: +49 69 6782 258; e-mail: rhenschler{at}web.de

Received March 8, 2007; accepted for publication May 3, 2007.
First published online in STEM CELLS EXPRESS   May 17, 2007.



Although mesenchymal stromal cells (MSCs) are being increasingly used as cell therapeutics in clinical trials, the mechanisms that regulate their chemotactic migration behavior are incompletely understood. We aimed to better define the ability of the GTPase regulator of cytoskeletal activation, Rho, to modulate migration induction in MSCs in a transwell chemotaxis assay. We found that culture-expanded MSCs migrate poorly toward exogenous phospholipids lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) in transwell assays. Moreover, plasma-induced chemotactic migration of MSCs was even inhibited after pretreatment with LPA. LPA treatment activated intracellular Rho and increased actin stress fibers in resident MSCs. Very similar cytoskeletal changes were observed after microinjection of a cDNA encoding constitutively active RhoA (RhoAV14) in MSCs. In contrast, microinjection of cDNA encoding Rho inhibitor C3 transferase led to resolution of actin stress fibers, appearance of a looser actin meshwork, and increased numbers of cytoplasmic extensions in the MSCs. Surprisingly, in LPA-pretreated MSCs migrating toward plasma, simultaneous addition of Rho inhibitor C2I-C3 reversed LPA-induced migration suppression and led to improved migration. Moreover, addition of Rho inhibitor C2I-C3 resulted in an approximately 3- to 10-fold enhancement of chemotactic migration toward LPA, S1P, as well as platelet-derived growth factor or hepatocyte growth factor. Thus, inhibition of Rho induces rearrangement of actin cytoskeleton in MSCs and renders them susceptible to induction of migration by physiological stimuli.

Disclosure of potential conflicts of interest is found at the end of this article.