Data_Sheet_3_Anatomical and Surgical Evaluation of the Common Marmoset as an Animal Model in Hearing Research.pdf

Recent studies have indicated that direct administration of viral vectors or small compounds to the inner ear may aid in the treatment of Sensorineural hearing loss (SNHL). However, due to species differences between humans and rodents, translating experimental results into clinical applications remains challenging. The common marmoset (Callithrix jacchus), a New World monkey, is considered a pre-clinical animal model. In the present study, we describe morphometric data acquired from the temporal bone of the common marmoset in order to define the routes of topical drug administration to the inner ear. Dissection and diffusion tensor tractography (DTT) were performed on the fixed cadaverous heads of 13 common marmosets. To investigate potential routes for drug administration to the inner ear, we explored the anatomy of the round window, oval window (OW), semicircular canal, and endolymphatic sac (ES). Among these, the approach via the round window with posterior tympanotomy appeared feasible for delivering drugs to the inner ear without manipulating the tympanic membrane, minimizing the chances of conductive hearing loss. The courses of four critical nerves [including the facial nerve (FN)] were visualized using three-dimensional (3D) DTT, which may help to avoid nerve damage during surgery. Finally, to investigate the feasibility of actual drug administration, we measured the volume of the round window niche (RWN), which was approximately 0.9 μL. The present findings may help to establish experimental standards for evaluating new therapies in this primate model.

近期研究表明，直接向内耳递送病毒载体或小分子化合物，或可辅助治疗感音神经性听力损失（Sensorineural hearing loss, SNHL）。然而，由于人类与啮齿类动物存在物种差异，将实验结果转化为临床应用仍面临挑战。普通狨（Callithrix jacchus）作为一种新世界猴，被视为理想的临床前动物模型。本研究采集了普通狨颞骨的形态计量学数据，旨在明确内耳局部给药的路径。研究人员对13例普通狨的固定尸体头颅进行了解剖及弥散张量纤维束成像（diffusion tensor tractography, DTT）。为探究内耳给药的潜在路径，我们对圆窗、卵圆窗（oval window, OW）、半规管及内淋巴囊（endolymphatic sac, ES）的解剖结构进行了分析。其中，经后鼓室切开术暴露圆窗的给药路径，可在不触碰鼓膜的前提下将药物递送至内耳，最大程度降低传导性听力损失的发生风险。研究通过三维（three-dimensional, 3D）DTT可视化了包括面神经（facial nerve, FN）在内的4条关键神经的走行，这有助于规避手术过程中神经损伤的风险。最后，为验证实际给药的可行性，我们测量了圆窗龛（round window niche, RWN）的容积，其约为0.9 μL。本研究结果可为该灵长类动物模型中新疗法的评估建立实验标准。