Seven Yasin B, Seven Elif S, Kirbas Cilingir Emel, Parikh Komal, Aydin Mehmet, Luca Edward K, Nair Jayakrishnan, Leblanc Roger M
Dept. of Physiological Sciences, University of Florida, Gainesville, FL, 32603, USA.
Breathing Research and Therapeutics (BREATHE) Center, University of Florida, Gainesville, FL.
Nanoscale. 2025 Aug 26. doi: 10.1039/d5nr02670a.
The spinal cord is a highly dynamic network, playing significant roles in the vital functions of the brain. Disorders of the spinal cord, such as spinal cord injury and amyotrophic lateral sclerosis (ALS), are associated with neurodegeneration, often resulting in morbidity and mortality. The blood-brain barrier (BBB) poses a major challenge to imaging and therapeutic agents because less than 2% of small-molecule drugs and almost no large-molecule drugs can cross the BBB. Furthermore, spatial spectroscopy studies have shown highly heterogeneous BBB crossing with significant accumulation at the unintended brain regions. Thus, targeting systems that can cross the BBB at the spinal cord and precisely target specific cell types/populations are vitally needed. Carbon dots can be custom-designed to accumulate at the spinal cord; thus, they offer great potential as delivery platforms for imaging and therapeutic approaches. Since neurons are metabolically highly active and rely on glucose, we designed glucose-based carbon dots (GluCDs) with a diameter of ∼4 nm and glucose-like surface groups. We determined the CNS distribution of GluCDs on three scales: 1. brain regional distribution, 2. cellular tropism ( neurons glia), and 3. intracellular localization. We found that GluCDs (1) crossed the BBB at the spinal cord level, localized primarily to the spinal cord, and were quickly transported to higher centers in the brain, revealing supraspinal connectome within 4 hours after systemic delivery (minimally invasive and significantly faster than the available technologies); (2) almost exclusively localized to neurons without the need for a targeting ligand (neuronal self-targeting), and (3) were confined to late endosomal/lysosomal compartments in the neurons. Then, we verified our findings in a cervical spinal cord contusion injury model with GluCDs targeting the neurons at the injury epicenter. Therefore, GluCDs can be used as robust imaging agents to obtain rapid snapshots of the spinal/supraspinal network. GluCD nanoconjugates can open new avenues for targeted imaging of spinal cord injury. These findings can be extended to other spinal disorders such as ALS, spinal muscular atrophy, and spinal stroke.
脊髓是一个高度动态的网络，在大脑的重要功能中发挥着重要作用。脊髓疾病，如脊髓损伤和肌萎缩侧索硬化症（ALS），与神经退行性变有关，常常导致发病和死亡。血脑屏障（BBB）对成像和治疗药物构成了重大挑战，因为小分子药物中只有不到2%能够穿过血脑屏障，而几乎没有大分子药物能够穿过。此外，空间光谱研究表明，血脑屏障的穿透具有高度异质性，在非预期的脑区有显著积累。因此，迫切需要能够在脊髓处穿过血脑屏障并精确靶向特定细胞类型/群体的靶向系统。碳点可以经过定制设计使其在脊髓处积累；因此，它们作为成像和治疗方法的递送平台具有巨大潜力。由于神经元代谢高度活跃且依赖葡萄糖，我们设计了直径约为4 nm且具有类似葡萄糖表面基团的基于葡萄糖的碳点（GluCDs）。我们在三个尺度上确定了GluCDs在中枢神经系统中的分布：1. 脑区分布，2. 细胞嗜性（神经元与神经胶质细胞），以及3. 细胞内定位。我们发现GluCDs（1）在脊髓水平穿过血脑屏障，主要定位于脊髓，并迅速被转运至大脑的更高中枢，在全身给药后4小时内揭示了脊髓上连接组（微创且比现有技术快得多）；（2）几乎完全定位于神经元，无需靶向配体（神经元自我靶向），并且（3）局限于神经元内的晚期内体/溶酶体区室。然后，我们在颈脊髓挫伤损伤模型中用靶向损伤中心神经元的GluCDs验证了我们的发现。因此，GluCDs可以用作强大的成像剂来快速获取脊髓/脊髓上网络的快照。GluCD纳米缀合物可以为脊髓损伤的靶向成像开辟新途径。这些发现可以扩展到其他脊髓疾病，如ALS、脊髓性肌萎缩症和脊髓中风。
