Crigler Lauren, Robey Rebecca C, Asawachaicharn Amy, Gaupp Dina, Phinney Donald G
SL-99, Center for Gene Therapy, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
Exp Neurol. 2006 Mar;198(1):54-64. doi: 10.1016/j.expneurol.2005.10.029. Epub 2005 Dec 5.
Mesenchymal stem cells (MSCs) transplanted at sites of nerve injury are thought to promote functional recovery by producing trophic factors that induce survival and regeneration of host neurons. To evaluate this phenomenon further, we quantified in human MSCs neurotrophin expression levels and their effects on neuronal cell survival and neuritogenesis. Screening a human MSC cDNA library revealed expressed transcripts encoding BDNF and beta-NGF but not NT-3 and NT-4. Immunostaining demonstrated that BDNF and beta-NGF proteins were restricted to specific MSC subpopulations, which was confirmed by ELISA analysis of 56 separate subclones. Using a co-culture assay, we also demonstrated that BDNF expression levels correlated with the ability of MSC populations or subclones to induce survival and neurite outgrowth in the SH-SY5Y neuroblastoma cell line. However, these MSC-induced effects were only partially inhibited by a neutralizing anti-BDNF antibody. MSCs were also shown to promote neurite outgrowth within dorsal root ganglion explants despite secreting 25-fold lower level of beta-NGF required exogenously to produce a similar effect. Interrogation of the human MSC transcriptome identified expressed mRNAs encoding various neurite-inducing factors, axon guidance and neural cell adhesion molecules. Moreover, a subset of these transcripts was shown to correlate with BDNF expression in MSC subclones. Collectively, these studies reveal the existence of MSC subpopulations that co-express neurotrophins and other potent neuro-regulatory molecules, which contribute to MSC-induced effects on neuronal cell survival and nerve regeneration. These subpopulations may represent more potent vectors for treating a variety of neurological disorders.
在神经损伤部位移植的间充质干细胞（MSC）被认为可通过产生诱导宿主神经元存活和再生的营养因子来促进功能恢复。为了进一步评估这一现象，我们对人MSC中神经营养因子的表达水平及其对神经元细胞存活和神经突形成的影响进行了定量分析。对人MSC cDNA文库进行筛选，发现有编码BDNF和β-NGF的转录本表达，但未发现NT-3和NT-4的转录本。免疫染色表明，BDNF和β-NGF蛋白局限于特定的MSC亚群，对56个单独亚克隆进行ELISA分析证实了这一点。使用共培养试验，我们还证明BDNF表达水平与MSC群体或亚克隆在SH-SY5Y神经母细胞瘤细胞系中诱导存活和神经突生长的能力相关。然而，这些MSC诱导的效应仅被一种中和性抗BDNF抗体部分抑制。尽管MSC分泌的β-NGF水平比外源性产生类似效应所需的水平低25倍，但仍显示其能促进背根神经节外植体中的神经突生长。对人MSC转录组进行分析，鉴定出编码各种神经突诱导因子、轴突导向分子和神经细胞粘附分子的mRNA表达。此外，这些转录本中的一部分显示与MSC亚克隆中的BDNF表达相关。总的来说，这些研究揭示了共表达神经营养因子和其他强效神经调节分子的MSC亚群的存在，这些亚群有助于MSC对神经元细胞存活和神经再生的诱导作用。这些亚群可能代表治疗多种神经系统疾病的更有效载体。
