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Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Mar 26, 2016; 8(3): 73-87
Published online Mar 26, 2016. doi: 10.4252/wjsc.v8.i3.73
Homing and migration of mesenchymal stromal cells: How to improve the efficacy of cell therapy?
Ann De Becker, Ivan Van Riet
Ann De Becker, Ivan Van Riet, Department Clinical Hematology-Stem Cell Laboratory, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), 1090 Jette, Belgium
Author contributions: Both authors contributed equally to the conception of the paper, the literature review and analysis, and drafting, and to critically revising and editing the manuscript.
Conflict-of-interest statement: There are no potential conflicts of interest, as there was no financial support for this article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Ivan Van Riet, MSc, PhD, Department Clinical Hematology-Stem Cell Laboratory, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Laarbeeklaan 101, 1090 Jette, Belgium. ivan.vanriet@uzbrussel.be
Telephone: +32-2-4776211 Fax: +32-2-4776210
Received: August 29, 2015
Peer-review started: September 6, 2015
First decision: November 11, 2015
Revised: December 24, 2015
Accepted: January 27, 2016
Article in press: January 29, 2016
Published online: March 26, 2016
Abstract

Mesenchymal stromal cells (MSCs) are currently being investigated for use in a wide variety of clinical applications. For most of these applications, systemic delivery of the cells is preferred. However, this requires the homing and migration of MSCs to a target tissue. Although MSC homing has been described, this process does not appear to be highly efficacious because only a few cells reach the target tissue and remain there after systemic administration. This has been ascribed to low expression levels of homing molecules, the loss of expression of such molecules during expansion, and the heterogeneity of MSCs in cultures and MSC culture protocols. To overcome these limitations, different methods to improve the homing capacity of MSCs have been examined. Here, we review the current understanding of MSC homing, with a particular focus on homing to bone marrow. In addition, we summarize the strategies that have been developed to improve this process. A better understanding of MSC biology, MSC migration and homing mechanisms will allow us to prepare MSCs with optimal homing capacities. The efficacy of therapeutic applications is dependent on efficient delivery of the cells and can, therefore, only benefit from better insights into the homing mechanisms.

Keywords: Mesenchymal stromal cells, Homing, Bone marrow, Homing receptors, Extravasation

Core tip: Mesenchymal stromal cells (MSCs) are currently under investigation for use in a variety of clinical applications. In most studies, MSCs are administered systemically. This requires efficient homing and migration of the MSCs to a target tissue. However, the homing mechanisms of MSCs are not completely understood. Moreover, the in vivo homing and migration of MSCs does not appear to be highly efficient. Therefore, different methods have been investigated to improve homing. Here, we will review the current knowledge of bone marrow homing of MSCs, as well as the different strategies that might improve the homing capacity of these stem cells.