Thalamic infusion of adeno-associated viral (AAV) vectors has been shown to have therapeutic effects in neuronopathic lysosomal storage diseases. Preclinical studies in sheep model of Tay-Sachs disease demonstrated that bilateral thalamic injections of AAV gene therapy are required for maximal benefit. Translation of thalamic injection to patients carries risks in that 1) it has never been done in humans, and 2) dosing scale-up based on brain weight from animals to humans requires injection of larger volumes. To increase the safety margin of this infusion, a flexible cannula was selected to enable simultaneous bilateral thalamic infusion in infants while monitoring by imaging and/or to enable awake infusions for injection of large volumes at low infusion rates. In this study, we tested various infusion volumes (200–800 µL) and rates (0.5–5 µL/min) to determine the maximum tolerated combination of injection parameters. Animals were followed for ~1 month post-injection with MRI performed at 14 and 28 days. T1-weighted MRI was used to quantify thalamic damage followed by histopathological assessment of the brain. Trends in data show that infusion volumes of 800 µL (2× the volume required in sheep based on thalamic size) resulted in larger lesions than lower volumes, where the long infusion times (between 13 to 26 hours) could have contributed to the generation of larger lesions. The target volume (400 µL, projected to be sufficient to cover most of the sheep thalamus) created the smallest lesion size. Cannula placement alone did result in damage, but this is likely associated with an inherent limitation of its use in a small brain due to the length of the distal rigid portion and lack of stable fixation. An injection rate of 5 µL/min at a volume approximately 1/3 of the thalamus (400µL-600µL) appears to be well tolerated in sheep both clinically and histopathologically.

中文翻译：

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大型动物模型实质内中枢神经系统输注的体积和输注速率动力学

丘脑输注腺相关病毒（AAV）载体已显示在神经性溶酶体贮积病中具有治疗作用。在绵羊Tay-Sachs病模型中的临床前研究表明，双侧丘脑注射AAV基因疗法是获得最大益处的必要条件。丘脑注射给患者带来的风险在于：1）在人类中从未做到过； 2）根据从动物到人类的脑重量扩大剂量，需要注射更大的剂量。为了增加这种输注的安全性，选择了挠性套管以使婴儿能够同时进行双侧丘脑输注，同时通过成像进行监视和/或使清醒输注能够以低输注速率进行大剂量注射。在这项研究中，我们测试了各种输液量（200–800 µL）和速率（0。5–5 µL / min）确定注射参数的最大容许组合。在注射后第14和28天对动物进行〜1个月的MRI检查。T1加权MRI用于定量丘脑损伤，然后对大脑进行组织病理学评估。数据趋势表明，输注量为800 µL（是丘脑大小的两倍，是绵羊所需量）导致的损害要大于较小的输注量，而较长的输注时间（13至26小时之间）可能有助于产生较大的病灶。目标体积（400 µL，预计足以覆盖大部分绵羊丘脑）产生了最小的病变。光是插管就造成了损害，但是，由于远端刚性部分的长度和缺乏稳定的固定，这可能与其在小脑中使用的固有限制有关。在绵羊的丘脑（400µL-600µL）的大约1/3的体积中，注射速度为5 µL / min在临床和组织病理学上似乎都可以很好地耐受。