Neuroregeneration Laboratory, Department of Anesthesiology, University of California San Diego, La Jolla, California, USA.
PLoS One. 2012;7(8):e42614. doi: 10.1371/journal.pone.0042614. Epub 2012 Aug 20.
Mutation in the ubiquitously expressed cytoplasmic superoxide dismutase (SOD1) causes an inherited form of Amyotrophic Lateral Sclerosis (ALS). Mutant synthesis in motor neurons drives disease onset and early disease progression. Previous experimental studies have shown that spinal grafting of human fetal spinal neural stem cells (hNSCs) into the lumbar spinal cord of SOD1(G93A) rats leads to a moderate therapeutical effect as evidenced by local α-motoneuron sparing and extension of lifespan. The aim of the present study was to analyze the degree of therapeutical effect of hNSCs once grafted into the lumbar spinal ventral horn in presymptomatic immunosuppressed SOD1(G93A) rats and to assess the presence and functional integrity of the descending motor system in symptomatic SOD1(G93A) animals.
METHODS/PRINCIPAL FINDINGS: Presymptomatic SOD1(G93A) rats (60-65 days old) received spinal lumbar injections of hNSCs. After cell grafting, disease onset, disease progression and lifespan were analyzed. In separate symptomatic SOD1(G93A) rats, the presence and functional conductivity of descending motor tracts (corticospinal and rubrospinal) was analyzed by spinal surface recording electrodes after electrical stimulation of the motor cortex. Silver impregnation of lumbar spinal cord sections and descending motor axon counting in plastic spinal cord sections were used to validate morphologically the integrity of descending motor tracts. Grafting of hNSCs into the lumbar spinal cord of SOD1(G93A) rats protected α-motoneurons in the vicinity of grafted cells, provided transient functional improvement, but offered no protection to α-motoneuron pools distant from grafted lumbar segments. Analysis of motor-evoked potentials recorded from the thoracic spinal cord of symptomatic SOD1(G93A) rats showed a near complete loss of descending motor tract conduction, corresponding to a significant (50-65%) loss of large caliber descending motor axons.
CONCLUSIONS/SIGNIFICANCE: These data demonstrate that in order to achieve a more clinically-adequate treatment, cell-replacement/gene therapy strategies will likely require both spinal and supraspinal targets.
细胞质超氧化物歧化酶（SOD1）的普遍表达突变导致遗传性肌萎缩侧索硬化症（ALS）。运动神经元中的突变合成驱动疾病的发作和早期疾病进展。先前的实验研究表明，将人胎儿脊髓神经干细胞（hNSC）移植到 SOD1（G93A）大鼠的腰脊髓中，会导致局部α运动神经元保留和寿命延长，从而产生适度的治疗效果。本研究的目的是分析 hNSC 一旦移植到 SOD1（G93A）大鼠的腰脊髓腹角中的治疗效果程度，并评估症状性 SOD1（G93A）动物中下行运动系统的存在和功能完整性。
方法/主要发现：接受 SOD1（G93A）大鼠（60-65 天大）的腰脊髓注射 hNSC。细胞移植后，分析疾病发作、疾病进展和寿命。在单独的症状性 SOD1（G93A）大鼠中，通过电刺激运动皮层后，使用脊髓表面记录电极分析下行运动束（皮质脊髓和红核脊髓）的存在和功能传导性。用银浸渍法对腰脊髓节段进行染色，并在塑料脊髓节段中对下行运动轴突进行计数，以验证下行运动束的形态完整性。将 hNSC 移植到 SOD1（G93A）大鼠的腰脊髓中，可保护移植细胞附近的α运动神经元，提供短暂的功能改善，但不能保护远离移植腰段的α运动神经元池。对症状性 SOD1（G93A）大鼠的胸脊髓记录的运动诱发电位进行分析，结果显示下行运动束的传导几乎完全丧失，与大口径下行运动轴突的显著（50-65%）丧失相对应。
结论/意义：这些数据表明，为了实现更具临床意义的治疗效果，细胞替代/基因治疗策略可能需要同时针对脊髓和脊髓以上的目标。
