Alfaro Maria P, Pagni Matthew, Vincent Alicia, Atkinson James, Hill Michael F, Cates Justin, Davidson Jeffrey M, Rottman Jeffrey, Lee Ethan, Young Pampee P
Department of Pathology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Proc Natl Acad Sci U S A. 2008 Nov 25;105(47):18366-71. doi: 10.1073/pnas.0803437105. Epub 2008 Nov 18.
Cell-based therapies, using multipotent mesenchymal stem cells (MSCs) for organ regeneration, are being pursued for cardiac disease, orthopedic injuries and biomaterial fabrication. The molecular pathways that regulate MSC-mediated regeneration or enhance their therapeutic efficacy are, however, poorly understood. We compared MSCs isolated from MRL/MpJ mice, known to demonstrate enhanced regenerative capacity, to those from C57BL/6 (WT) mice. Compared with WT-MSCs, MRL-MSCs demonstrated increased proliferation, in vivo engraftment, experimental granulation tissue reconstitution, and tissue vascularity in a murine model of repair stimulation. The MRL-MSCs also reduced infarct size and improved function in a murine myocardial infarct model compared with WT-MSCs. Genomic and functional analysis indicated a downregulation of the canonical Wnt pathway in MRL-MSCs characterized by significant up-regulation of specific secreted frizzled-related proteins (sFRPs). Specific knockdown of sFRP2 by shRNA in MRL-MSCs decreased their proliferation and their engraftment in and the vascular density of MRL-MSC-generated experimental granulation tissue. These results led us to generate WT-MSCs overexpressing sFRP2 (sFRP2-MSCs) by retroviral transduction. sFRP2-MSCs maintained their ability for multilineage differentiation in vitro and, when implanted in vivo, recapitulated the MRL phenotype. Peri-infarct intramyocardial injection of sFRP2-MSCs resulted in enhanced engraftment, vascular density, reduced infarct size, and increased cardiac function after myocardial injury in mice. These findings implicate sFRP2 as a key molecule for the biogenesis of a superior regenerative phenotype in MSCs.
利用多能间充质干细胞（MSC）进行器官再生的细胞疗法正在被用于治疗心脏病、骨科损伤和生物材料制造。然而，调节MSC介导的再生或增强其治疗效果的分子途径却知之甚少。我们将从已知具有增强再生能力的MRL/MpJ小鼠中分离出的MSC与C57BL/6（野生型，WT）小鼠的MSC进行了比较。与WT-MSC相比，MRL-MSC在修复刺激的小鼠模型中表现出增殖增加、体内植入、实验性肉芽组织重建和组织血管生成增强。与WT-MSC相比，MRL-MSC在小鼠心肌梗死模型中还减少了梗死面积并改善了心脏功能。基因组和功能分析表明，MRL-MSC中经典Wnt通路下调，其特征是特定分泌型卷曲相关蛋白（sFRP）显著上调。通过shRNA在MRL-MSC中特异性敲低sFRP2可降低其增殖、在MRL-MSC生成的实验性肉芽组织中的植入以及血管密度。这些结果促使我们通过逆转录病毒转导产生过表达sFRP2的WT-MSC（sFRP2-MSC）。sFRP2-MSC在体外保持了其多向分化能力，并且在体内植入时重现了MRL表型。在小鼠心肌损伤后，梗死周边心肌内注射sFRP2-MSC导致植入增强、血管密度增加、梗死面积减小以及心脏功能增强。这些发现表明sFRP2是MSC中产生优越再生表型的关键分子。
