Riaz Muhammad, Raz Yotam, Moloney Elizabeth B, van Putten Maaike, Krom Yvonne D, van der Maarel Silvere M, Verhaagen Joost, Raz Vered
Department of Human Genetics, Leiden University Medical Center, Building 2, Room R3-17, Einthovenweg 20, 2333 ZC Leiden, The Netherlands.
Department of Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, Royal Dutch Academy of Sciences, Amsterdam, The Netherlands.
Skelet Muscle. 2015 Nov 10;5:37. doi: 10.1186/s13395-015-0064-4. eCollection 2015.
Gene therapy strategies are promising therapeutic options for monogenic muscular dystrophies, with several currently underways. The adeno-associated viral (AAV) vector is among the most effective gene delivery systems. However, transduction efficiency in skeletal muscles varies between AAV serotypes, with the underlying factors poorly understood. We hypothesized that myofiber-specific tropism differs between AAV serotypes.
We developed a quantitative histology procedure and generated myofiber pattern maps for four myosin heavy chain (MyHC) isotypes. We compared myofiber pattern maps between AAV6 or AAV9 injected tibialis anterior muscle in mice. We correlated MyHC expression with AAV-derived green fluorescence protein (GFP) expression using statistical models.
We found that MyHC-2x expressing myofibers display a significantly higher preference for AAV transduction, whereas MyHC-2b expressing myofibers negatively correlated with AAV transduction. In addition, we show that AAV9-mediated transduction is enriched in myofibers expressing MyHC-1 and MyHC-1/2a. Moreover, AAV9-mediated transduction can predominantly be predicted by the expression of MyHC isotypes. In contrast, AAV6 transduction can be predicted by myofiber size but not by myofiber types.
Our findings identify differences between AAV6 and AAV9 for myofiber-type preferences, which could be an underlying factor for mosaic transduction of skeletal muscle. Adjusting AAV serotype for specific muscle conditions can therefore improve transduction efficacy in clinical applications.
基因治疗策略是单基因肌营养不良症很有前景的治疗选择，目前有几种正在进行中。腺相关病毒（AAV）载体是最有效的基因递送系统之一。然而，骨骼肌中的转导效率在不同AAV血清型之间存在差异，其潜在因素尚不清楚。我们假设不同AAV血清型的肌纤维特异性嗜性不同。
我们开发了一种定量组织学程序，并生成了四种肌球蛋白重链（MyHC）同型的肌纤维模式图。我们比较了注射AAV6或AAV9的小鼠胫前肌之间的肌纤维模式图。我们使用统计模型将MyHC表达与AAV衍生的绿色荧光蛋白（GFP）表达相关联。
我们发现表达MyHC-2x的肌纤维对AAV转导表现出明显更高的偏好，而表达MyHC-2b的肌纤维与AAV转导呈负相关。此外，我们表明AAV9介导的转导在表达MyHC-1和MyHC-1/2a的肌纤维中富集。此外，AAV9介导的转导主要可以通过MyHC同型的表达来预测。相比之下，AAV6转导可以通过肌纤维大小而不是肌纤维类型来预测。
我们的研究结果确定了AAV6和AAV9在肌纤维类型偏好上的差异，这可能是骨骼肌镶嵌转导的一个潜在因素。因此，针对特定肌肉状况调整AAV血清型可以提高临床应用中的转导效率。
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