Kyriakou Charalampia, Rabin Neil, Pizzey Arnold, Nathwani Amit, Yong Kwee
UCL Cancer Institute, 72 Huntley Street, London Wc1E 6DD, United Kingdom.
Haematologica. 2008 Oct;93(10):1457-65. doi: 10.3324/haematol.12553. Epub 2008 Aug 25.
Human mesenchymal stem cells are potential agents for tissue regeneration, enhancing hematopoietic stem cell transplantation and delivering genes of therapeutic interest. To implement any of these strategies successfully, we need a better understanding of factors that influence the tissue distribution of systemically administered mesenchymal stem cells.
The present study was designed to investigate the short-term tissue homing of mesenchymal stem cells in immunodeficient mouse models, exploring the effects of animal age, duration of ex vivo expansion of mesenchymal stem cells, lentiviral transduction and CXCR4 over-expression. Dye-labeled mesenchymal stem cells (1.5-2.0 x 10(6)/animal) were injected via the tail vein into unconditioned beta2m/NOD/SCID animals. Animals were sacrificed 20-24 hours later and cell suspensions from tissues were examined by flow cytometry for the presence of PKH-positive cells.
PKH-positive cells were readily detected in the bone marrow, spleen, liver and lungs at 20-24 hours after infusion. The homing of systemically infused mesenchymal stem cells to the bone marrow and spleen of unconditioned beta2m/NOD/SCID animals was significantly (>2-fold, p<0.001) higher in younger (<10 weeks) animals, and was reduced with increasing passage number. Despite low surface CXCR4 expression, human mesenchymal stem cells migrated to SDF-1 in vitro, and this was enhanced by over-expression of CXCR4 using lentiviral transduction. Over-expression of CXCR4 by lentiviral transduction (>80%) did not alter the bone marrow homing of mesenchymal stem cells in unconditioned animals, but caused a significant (p<0.05) increase in homing to bone marrow and spleen of animals that had received prior irradiation.
Tissue homing of systemically administered mesenchymal stem cells is influenced by host factors such as age, is diminished by prolonged in vitro culture, and can be increased by enforced expression of CXCR4, at least in irradiated hosts.
人间充质干细胞是组织再生、增强造血干细胞移植及递送具有治疗意义基因的潜在介质。要成功实施这些策略中的任何一项，我们需要更好地了解影响全身给药间充质干细胞组织分布的因素。
本研究旨在研究免疫缺陷小鼠模型中间充质干细胞的短期组织归巢情况，探讨动物年龄、间充质干细胞体外扩增时间、慢病毒转导及CXCR4过表达的影响。将染料标记的间充质干细胞（1.5 - 2.0 x 10(6)/只动物）经尾静脉注射到未预处理的β2m/NOD/SCID动物体内。20 - 24小时后处死动物，通过流式细胞术检测组织细胞悬液中PKH阳性细胞的存在情况。
输注后20 - 24小时，在骨髓、脾脏、肝脏和肺中很容易检测到PKH阳性细胞。全身输注的间充质干细胞向未预处理的β2m/NOD/SCID动物骨髓和脾脏的归巢在年轻（<10周）动物中显著更高（>2倍，p<0.001），且随着传代次数增加而减少。尽管人骨髓间充质干细胞表面CXCR4表达较低，但在体外可迁移至SDF - 1，且通过慢病毒转导过表达CXCR4可增强这种迁移。慢病毒转导使CXCR4过表达（>80%）并未改变未预处理动物中间充质干细胞的骨髓归巢，但导致接受过照射的动物向骨髓和脾脏的归巢显著增加（p<0.05）。
全身给药间充质干细胞的组织归巢受年龄等宿主因素影响，体外长时间培养会使其降低，至少在受照射宿主中，CXCR4的强制表达可增加其归巢。
