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.

中文翻译：

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间充质基质细胞的归巢和迁移：如何提高细胞疗法的疗效？

目前正在研究间充质基质细胞（MSC）在各种临床应用中的用途。对于大多数这些应用，细胞的全身递送是优选的。但是，这需要将MSC归巢和迁移到目标组织。尽管已经描述了MSC归巢，但是该过程似乎不是高效的，因为在全身给药后只有少数细胞到达靶组织并保留在那里。这归因于归巢分子的低表达水平，在扩增过程中此类分子的表达损失以及培养物和MSC培养方案中MSC的异质性。为了克服这些限制，已经研究了提高MSC归巢能力的不同方法。在这里，我们回顾了对MSC归位的最新理解，特别着重于归巢到骨髓。此外，我们总结了为改进此过程而开发的策略。对MSC生物学，MSC迁移和归巢机制的更好理解将使我们能够准备具有最佳归巢能力的MSC。治疗应用的功效取决于细胞的有效传递，因此只能从对归巢机制的更深入了解中受益。