Fibulin-3 (Fib3) is a secreted glycoprotein that is expressed in the retina and has been associated with drusen formation in age-related macular degeneration (AMD). The purpose of this study was to assess whether Fib3 is associated with extracellular vesicles (EVs) in drusen from non-diseased and AMD human donors. De-identified sections of human eyes were received from the National Disease Research Institute (NDRI, Philadelphia). Donor eyes were either non-diseased (no known ocular pathology) or had been diagnosed with AMD. Retinal cryostat sections were labeled with primary antibodies targeted to Fib3, Apolipoprotein E (ApoE; a drusen marker), and ALG-2 interacting protein X (Alix, an EV marker) for confocal imaging (Leica TCS SP8). Fib3-positive (Fib3⁺) puncta were detected on the apical region of the RPE layer and within large AMD drusen. Alix-positive (Alix⁺) puncta were also detected in a single AMD druse, where a number were Fib3⁺ and the remaining were Fib3-negative. Similarly, there were Fib3⁺ puncta that were Alix-negative. Fib3 and Alix also showed a degree of colocalization in the photoreceptor outer segments of the neural retina. Our data suggest that the Alix⁺ puncta are EV-rich populations that accumulate, together with Fib3, within the drusen matrix during AMD. The EV population is likely heterogeneous, such that there are sub-populations with different cargo content.

Fibulin-3（Fib3）是一种分泌的糖蛋白，在视网膜中表达，并与年龄相关性黄斑变性（AMD）中的玻璃疣形成有关。本研究的目的是评估Fib3是否与未患病和AMD人类供体的玻璃疣中的细胞外囊泡（EV）相关。来自美国国家疾病研究所（NDRI，费城）的人眼识别部分已被取消。捐献者的眼睛未患病（眼病理未知）或已被诊断患有AMD。视网膜低温恒温器切片用针对Fib3，载脂蛋白E（ApoE；玻璃疣标记）和ALG-2相互作用蛋白X（Alix，EV标记）的一抗标记，以进行共焦成像（Leica TCS SP8）。Fib3阳性（Fib3 ⁺）在RPE层的顶端区域和大型AMD玻璃疣中检出了点。在单个AMD疣中也检测到Alix阳性（Alix ⁺）泪点，其中一些为Fib3 ⁺，其余为Fib3阴性。同样，也有Alix阴性的Fib3 ⁺点。Fib3和Alix在神经视网膜的感光外段也显示出一定程度的共定位。我们的数据表明，在AMD期间，Alix ⁺泪点是富含EV的种群，与Fib3一起积累在玻璃疣基质内。EV人群可能是异类的，因此有一些具有不同货物含量的亚人群。