Published online Mar 26, 2016. doi: 10.4252/wjsc.v8.i3.73
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
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.
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.