科学家发现，把来自骨髓的人类干细胞直接注射到小鼠的大脑可以减少中风导致的损伤。此前的实验提示注射干细胞可以缓解动物的中风效应，这可能是由于它诱导了新神经元的生长。
Darwin Prockop及其同事如今发现注射干细胞可以通过触发现有细胞——小胶质细胞（神经细胞）和巨噬细胞（免疫细胞）——产生保护神经元和减轻炎症的生化物质从而产生康复作用。这组科学家证明了注射干细胞可以减少小鼠死亡或损伤的神经元数量。他们还调查了小鼠大脑血流暂时中断的时候脑基因的表达如何改变。这组作者发现在血流终止之后，586个基因的表达水平更高。这组作者说，但是当干细胞注射进大脑后，不到10%的基因表达上调，这提示这些基因很可能参与了炎症和免疫应答。相关论文发表在美国《国家科学院院刊》（PNAS）上。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS，doi: 10.1073/pnas.0803670105，Hirokazu Ohtaki，Darwin J. Prockop
Stem/progenitor cells from bone marrow decrease neuronal death in global ischemia by modulation of inflammatory/immune responses
Hirokazu Ohtaki, Joni H. Ylostalo, Jessica E. Foraker, Andrew P. Robinson, Roxanne L. Reger, Seiji Shioda, and Darwin J. Prockop
Human mesenchymal stromal cells (hMSCs) were injected into the hippocampus of adult mice 1 day after transient global ischemia. The hMSCs both improved neurologic function and markedly decreased neuronal cell death of the hippocampus. Microarray assays indicated that ischemia up-regulated 586 mouse genes. The hMSCs persisted for <7 days, but they down-regulated >10% of the ischemia-induced genes, most of which were involved in inflammatory and immune responses. The hMSCs also up-regulated three mouse genes, including the neuroprotective gene Ym1 that is expressed by activated microglia/macrophages. In addition, the transcriptomes of the hMSC changed with up-regulation of 170 human genes and down-regulation of 54 human genes. Protein assays of the hippocampus demonstrated increased expression in microglia/macrophages of Ym1, the cell survival factor insulin-like growth factor 1, galectin-3, cytokines reflective of a type 2 T cell immune bias, and the major histocompatibility complex II. The observed beneficial effects of hMSCs were largely explained by their modulation of inflammatory and immune responses, apparently by alternative activation of microglia and/or macrophages.
