Department of Biochemistry and Molecular Biology and Institute of Neurosciences, Edifici H, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Spain.
Unitat Mixta UAB-VHIR, Vall d'Hebron Institut de Recerca (VHIR), Barcelona, Spain.
Neurotherapeutics. 2020 Oct;17(4):2041-2053. doi: 10.1007/s13311-020-00865-y.
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare genetic disorder belonging to the group of vacuolating leukodystrophies. It is characterized by megalencephaly, loss of motor functions, epilepsy, and mild mental decline. In brain biopsies of MLC patients, vacuoles were observed in myelin and in astrocytes surrounding blood vessels. There is no therapy for MLC patients, only supportive treatment. We show here a preclinical gene therapy approach for MLC using the Mlc1 knock-out mouse. An adeno-associated virus coding for human MLC1 under the control of the glial fibrillary acidic protein promoter was injected in the cerebellar subarachnoid space of Mlc1 knock-out and wild-type animals at 2 months of age, before the onset of the disease, as a preventive approach. We also tested a therapeutic strategy by injecting the animals at 5 months, once the histopathological abnormalities are starting, or at 15 months, when they have progressed to a more severe pathology. MLC1 expression in the cerebellum restored the adhesion molecule GlialCAM and the chloride channel ClC-2 localization in Bergmann glia, which both are mislocalized in Mlc1 knock-out model. More importantly, myelin vacuolation was extremely reduced in treated mice at all ages and correlated with the amount of expressed MLC1 in Bergmann glia, indicating not only the preventive potential of this strategy but also its therapeutic capacity. In summary, here we provide the first therapeutic approach for patients affected with MLC. This work may have also implications to treat other diseases affecting motor function such as ataxias.
巨脑性脑白质营养不良伴皮质下囊肿（MLC）是一种罕见的遗传性疾病，属于空泡性脑白质营养不良。其特征为巨脑、运动功能丧失、癫痫发作和轻度智力下降。在 MLC 患者的脑活检中，发现髓磷脂和血管周围的星形胶质细胞中有空泡。目前尚无针对 MLC 患者的治疗方法，只有支持性治疗。我们在此展示了一种使用 Mlc1 基因敲除小鼠的 MLC 临床前基因治疗方法。腺相关病毒（AAV）编码受胶质纤维酸性蛋白启动子控制的人 MLC1，在疾病发作前（2 个月龄），通过小脑蛛网膜下腔注射到 Mlc1 基因敲除和野生型动物中，作为预防策略。我们还测试了一种治疗策略，即在出现组织病理学异常时（5 个月龄）或进展到更严重的病理阶段时（15 个月龄）对动物进行注射。小脑内 MLC1 的表达恢复了黏附分子 GlialCAM 和氯离子通道 ClC-2 在 Bergmann 胶质细胞中的定位，这两种分子在 Mlc1 基因敲除模型中均定位异常。更重要的是，在所有年龄的治疗小鼠中，髓鞘空泡化程度均显著降低，且与 Bergmann 胶质细胞中表达的 MLC1 量相关，这不仅表明了该策略的预防潜力，也表明了其治疗能力。总之，我们在此提供了针对 MLC 患者的首个治疗方法。这项工作也可能对治疗其他影响运动功能的疾病（如共济失调）具有重要意义。
