Park Joshua, Wicki Jacqueline, Knoblaugh Sue E, Chamberlain Jeffrey S, Lee Donghoon
Department of Radiology, University of Washington, Seattle, Washington, United States of America.
Department of Neurology, University of Washington, Seattle, Washington, United States of America.
PLoS One. 2015 Apr 9;10(4):e0124914. doi: 10.1371/journal.pone.0124914. eCollection 2015.
The objective of this study was to investigate the efficacy of using quantitative magnetic resonance imaging (MRI) as a non-invasive tool for the monitoring of gene therapy for muscular dystrophy. The clinical investigations for this family of diseases often involve surgical biopsy which limits the amount of information that can be obtained due to the invasive nature of the procedure. Thus, other non-invasive tools may provide more opportunities for disease assessment and treatment responses. In order to explore this, dystrophic mdx4cv mice were systemically treated with a recombinant adeno-associated viral (AAV) vector containing a codon-optimized micro-dystrophin gene. Multi-parametric MRI of T2, magnetization transfer, and diffusion effects alongside 3-D volume measurements were then utilized to monitor disease/treatment progression. Mice were imaged at 10 weeks of age for pre-treatment, then again post-treatment at 8, 16, and 24 week time points. The efficacy of treatment was assessed by physiological assays for improvements in function and quantification of expression. Tissues from the hindlimbs were collected for histological analysis after the final time point for comparison with MRI results. We found that introduction of the micro-dystrophin gene restored some aspects of normal muscle histology and pathology such as decreased necrosis and resistance to contraction-induced injury. T2 relaxation values showed percentage decreases across all muscle types measured (tibialis anterior, gastrocnemius, and soleus) when treated groups were compared to untreated groups. Additionally, the differences between groups were statistically significant for the tibialis anterior as well. The diffusion measurements showed a wider range of percentage changes and less statistical significance while the magnetization transfer effect measurements showed minimal change. MR images displayed hyper-intense regions of muscle that correlated with muscle pathology in histological sections. T2 relaxation, alongside diffusion and magnetization transfer effects provides useful data towards the goal of non-invasively monitoring the treatment of muscular dystrophy.
本研究的目的是调查使用定量磁共振成像（MRI）作为监测肌肉萎缩症基因治疗的非侵入性工具的疗效。对这类疾病的临床研究通常涉及手术活检，由于该操作具有侵入性，这限制了可获得的信息量。因此，其他非侵入性工具可能为疾病评估和治疗反应提供更多机会。为了探索这一点，对患肌营养不良症的mdx4cv小鼠全身注射含有密码子优化的微肌营养不良蛋白基因的重组腺相关病毒（AAV）载体进行治疗。然后利用T2、磁化传递和扩散效应的多参数MRI以及三维体积测量来监测疾病/治疗进展。在10周龄时对小鼠进行治疗前成像，然后在治疗后的第8、16和24周时间点再次成像。通过生理测定评估治疗效果，以观察功能改善和表达定量情况。在最后一个时间点后收集后肢组织进行组织学分析，以便与MRI结果进行比较。我们发现，微肌营养不良蛋白基因的导入恢复了正常肌肉组织学和病理学的某些方面，如坏死减少以及对收缩诱导损伤的抵抗力增强。与未治疗组相比，治疗组在所有测量的肌肉类型（胫前肌、腓肠肌和比目鱼肌）中，T2弛豫值均呈百分比下降。此外，胫前肌组间差异也具有统计学意义。扩散测量显示百分比变化范围更广且统计学意义较小，而磁化传递效应测量显示变化最小。MR图像显示肌肉的高强度区域与组织学切片中的肌肉病理学相关。T2弛豫以及扩散和磁化传递效应为非侵入性监测肌肉萎缩症治疗目标提供了有用数据。
