Wicking Dementia Research and Education Centre and NeuroRepair Group, Menzies Research Institute, University of Tasmania, Private Bag 29, Hobart, Tasmania, Australia 7000.
Brain Res. 2009 Dec 1;1300:24-36. doi: 10.1016/j.brainres.2009.08.059. Epub 2009 Aug 26.
While functional recovery after injury is limited, it has become evident that the mature central nervous system does retain some ability to regenerate. This study investigated the intrinsic capacity of relatively mature cortical neurons (21 days in vitro) to respond to axonal loss. Neurons, growing as clusters on poly-L-lysine, were completely sheared of axons through chemical and mechanical disruption and transferred to either an intact astrocyte monolayer or a substrate of poly-L-lysine. Injured neurons exhibited a regenerative sprouting response that was independent of neuronal cell division or neural progenitors, as demonstrated by negative bromodeoxyuridine (BrdU) and the neuronal precursor intermediate filament nestin, labeling. At 24 h after injury, neurons had extended appropriately polarized neurites, demonstrated by compartmentalized microtubule-associated proteins MAP2 and tau immunolabeling. Newly sprouting axons were tipped by growth cones; however, growth cones on the tips of sprouting axons (mean area, 26.32 +/- 2.20 microm) were significantly (p<0.05) smaller than their developmental counterparts (mean area, 48.64 +/- 5.9 microm), independent of substrate. Furthermore, live imaging indicated that regenerating neurons exhibited distinct axonal dynamics, with a significant (p<0.05) reduction (70%) in pausing, considered vital for interstitial branching and pathfinding, relative to developmental growth cones. This study indicates that mature cultured cortical pyramidal and interneurons have the intrinsic potential to survive, extend processes, and reestablish neurite polarity following significant physical damage. These results may aid in defining the cellular basis of neuronal structural plasticity and defining the role of astrocyte reactivity in the response to trauma.
尽管损伤后的功能恢复是有限的，但成熟的中枢神经系统确实保留了一些再生的能力，这一点已经很明显了。本研究调查了相对成熟的皮质神经元（体外培养 21 天）对轴突丢失的固有反应能力。神经元在多聚赖氨酸上成群生长，通过化学和机械破坏将其轴突完全切断，然后转移到完整的星形胶质细胞单层或多聚赖氨酸底物上。损伤后的神经元表现出再生性发芽反应，这与神经元细胞分裂或神经前体细胞无关，这一点可以通过溴脱氧尿苷（BrdU）和神经元前体细胞中间丝巢蛋白的阴性标记来证明。损伤后 24 小时，神经元已经延伸出适当的极化神经突，这可以通过微管相关蛋白 MAP2 和 tau 的免疫标记来证明。新发芽的轴突由生长锥尖端引导；然而，发芽轴突尖端的生长锥（平均面积 26.32 +/- 2.20 微米）明显（p<0.05）小于其发育性对应物（平均面积 48.64 +/- 5.9 微米），与底物无关。此外，活体成像表明，再生神经元表现出明显的轴突动力学特征，与发育性生长锥相比，停顿（被认为是间质分支和寻路的关键）显著减少（70%）。本研究表明，成熟培养的皮质锥体和中间神经元具有在受到严重物理损伤后存活、延伸过程和重新建立神经突极性的内在潜力。这些结果可能有助于定义神经元结构可塑性的细胞基础，并定义星形胶质细胞反应在创伤反应中的作用。
