Activation of CD74 inhibits migration of human mesenchymal stem cells Bonnie L. Barrilleaux & Benjamin W. Fischer-Valuck & Jennifer K. Gilliam & Donald G. Phinney & Kim C. O’Connor Received: 6 December 2009 / Accepted: 14 January 2010 / Published online: 3 March 2010 / Editor: J. Denry Sato # The Society for In Vitro Biology 2010 Abstract Therapeutic administration of mesenchymal stem cells (MSCs) by systemic delivery utilizes the innate ability of the cells to home to damaged tissues, but it can be an inefficient process due to a limited knowledge of cellular cues that regulate migration and homing. Our lab recently discovered that a potent pro-inflammatory cytokine, macro- phage migration inhibitory factor (MIF), inhibits MSC migration. Because MIF may act on multiple cellular targets, an activating antibody (CD74Ab) was employed in this study to examine the effect of one MIF receptor, CD74 (major histocompatibility complex class II-associated invariant chain), on MSC motility. CD74 activation inhibits in a dose- dependent manner up to 90% of in vitro migration of MSCs at 40 μg/ml CD74Ab (p <0.001), with consistent effects observed among three MSC donor preparations. A blocking peptide from the C-terminus of CD74 eliminates the effect of CD74Ab on MSCs. This suggests that MIF may act on MSCs, at least in part, through CD74. Late-passage MSCs exhibit less chemokinesis than those at passage 2. However, MSCs remain responsive to CD74 activation during ex vivo expansion: MSC migration is inhibited ∼2-fold in the presence of 5 μg/ml CD74Ab at passage 9 vs. ∼3-fold at passage 2 (p <0.001). Consistent with this result, there were no significant differences in CD74 expression at all tested passages or after CD74Ab exposure. Targeting CD74 to regulate migration and homing potentially may be a useful strategy to improve the efficacy of a variety of MSC therapies, including those that require ex vivo expansion. Keywords Mesenchymal stem cells . CD74 . Major histocompatibility complex class II-associated invariant chain . Chemokinesis . Migration Introduction Mesenchymal stem cells (MSCs) exhibit a remarkable capacity to regenerate damaged tissue (Barrilleaux et al. 2006). Therapeutic administration of MSCs by systemic delivery utilizes the innate ability of these adult stem cells to home to the injured site when infused into the bloodstream (Ortiz et al. 2003). Systemic delivery facilitates delivering multiple doses of stem cell therapy to patients and avoids the possibility of further trauma to damaged tissue that can occur with site-specific delivery (Fox et al. 2007). A disadvantage of intravenous infusion is that it can be an inefficient route of stem cell administration, resulting in low levels of MSC engraftment in targeted tissue (Zhang et al. 2008) with non- specific engraftment in healthy tissue (Barbash et al. 2003). The inability to actively direct the cells to target tissues and B. L. Barrilleaux : B. W. Fischer-Valuck : J. K. Gilliam : K. C. O’Connor (*) Department of Chemical and Biomolecular Engineering, Tulane University, Lindy Boggs Center Room 300, New Orleans, LA 70118, USA e-mail: koc@tulane.edu D. G. Phinney Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA Present Address: B. L. Barrilleaux Institute of Pediatric Regenerative Medicine, Shriners Hospital for Children, Sacramento, CA 95817, USA Present Address: B. W. Fischer-Valuck School of Medicine, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA In Vitro Cell.Dev.Biol.—Animal (2010) 46:566–572 DOI 10.1007/s11626-010-9279-1