Laboratory of Experimental Neurosurgery, Université Libre de Bruxelles, BE-1070 Brussels, Belgium.
Hum Gene Ther. 2012 Jul;23(7):742-53. doi: 10.1089/hum.2011.216. Epub 2012 Jun 5.
The adult rat brain subventricular zone (SVZ) contains proliferative precursors that migrate to the olfactory bulb (OB) and differentiate into mature neurons. Recruitment of precursors constitutes a potential avenue for brain repair. We have investigated the kinetics and cellular specificity of transgene expression mediated by AAV2/1 vectors (i.e., adeno-associated virus type 2 pseudotyped with AAV1 capsid) in the SVZ. Self-complementary (sc) and single-stranded (ss) AAV2/1 vectors mediated efficient GFP expression, respectively, at 17 and 24 hr postinjection. Transgene expression was efficient in all the rapidly proliferating cells types, that is, Mash1(+) precursors (30% of the GFP(+) cells), Dlx2(+) neuronal progenitors (55%), Olig2(+) oligodendrocyte progenitors (35%), and doublecortin-positive (Dcx(+)) migrating cells (40%), but not in the slowly proliferating glial fibrillary acidic protein-positive (GFAP(+)) neural stem cell pool (5%). Because cell cycle arrest by wild-type and recombinant AAV has been described in primary cultures, we examined SVZ proliferative activity after vector injection. Indeed, cell proliferation was reduced immediately after vector injection but was normal after 1 month. In contrast, migration and differentiation of GFP(+) precursors were unaltered. Indeed, the proportion of Dcx(+) cells was similar in the injected and contralateral hemispheres. Furthermore, 1 month after vector injection into the SVZ, GFP(+) cells, found, as expected, in the OB granular cell layer, were mature GABAergic neurons. In conclusion, the rapid and efficient transgene expression in SVZ neural precursors mediated by scAAV2/1 vectors underlines their potential usefulness for brain repair via recruitment of immature cells. The observed transient precursor proliferation inhibition, not affecting their migration and differentiation, will likely not compromise this strategy.
成年大鼠脑室下区 (SVZ) 含有增殖前体细胞，这些前体细胞迁移到嗅球 (OB) 并分化为成熟神经元。前体细胞的募集构成了大脑修复的潜在途径。我们研究了 AAV2/1 载体 (即，AAV1 衣壳假型的腺相关病毒 2) 在 SVZ 中介导的转基因表达的动力学和细胞特异性。自互补 (sc) 和单链 (ss) AAV2/1 载体分别在注射后 17 和 24 小时有效地介导 GFP 表达。转基因表达在所有快速增殖的细胞类型中都很有效，即 Mash1(+)前体细胞 (30%的 GFP(+)细胞)、Dlx2(+)神经元祖细胞 (55%)、Olig2(+)少突胶质前体细胞 (35%)和双皮质素阳性 (Dcx(+)迁移细胞 (40%)，但在增殖缓慢的神经胶质纤维酸性蛋白阳性 (GFAP(+))神经干细胞池 (5%)中则不然。因为野生型和重组 AAV 的细胞周期停滞已经在原代培养中被描述过，所以我们在载体注射后检查了 SVZ 的增殖活性。事实上，在载体注射后，细胞增殖立即减少，但 1 个月后恢复正常。相比之下，GFP(+)前体细胞的迁移和分化没有改变。事实上，在注射和对侧半球中，Dcx(+)细胞的比例相似。此外，在 SVZ 注射载体 1 个月后，GFP(+)细胞，如预期的那样，在 OB 颗粒细胞层中，是成熟的 GABA 能神经元。总之，scAAV2/1 载体介导的 SVZ 神经前体细胞中的快速和高效转基因表达突出了它们通过募集未成熟细胞用于大脑修复的潜在用途。观察到的短暂前体细胞增殖抑制不会影响其迁移和分化，不太可能损害这种策略。
