Polydopamine nanoparticles are artificial melanin nanoparticles (MNPs) that show strong antioxidant activity. The effects of MNPs on the neuroprotection of mesenchymal stem cells (MSCs) against hypoxic‐ischemic injury and the underlying mechanism have not yet been revealed. In this study, an oxygen–glucose deprivation (OGD)‐injured neuron model was used to mimic neuronal hypoxic‐ischemic injury in vitro. MSCs pretreated with MNPs and then cocultured with OGD‐injured neurons were used to investigate the potential effects of MNPs on the neuroprotection of MSCs and to elucidate the underlying mechanism. After coculturing with MNPs‐pretreated MSCs, MSCs, and MNPs in a transwell coculture system, the OGD‐injured neurons were rescued by 91.24%, 79.32%, and 59.97%, respectively. Further data demonstrated that MNPs enhanced the neuroprotection against hypoxic‐ischemic injury of MSCs by scavenging reactive oxygen species and superoxide and attenuating neuronal apoptosis by deactivating caspase‐3, downregulating the expression of proapoptotic Bax proteins, and upregulating the expression of antiapoptotic Bcl‐2 proteins. These findings suggest that MNPs enhance the neuroprotective effect of MSCs against hypoxic‐ischemic injury by inhibiting apoptosis and upregulating antioxidant defense, which could provide some evidence for the potential application of combined MNPs and MSCs in the therapy for ischemic stroke.

Stroke is the second leading cause of death and a major cause of disability worldwide. Ischemic stroke caused by atherosclerosis accounts for approximately 87% of all stroke cases. Ischemic stroke is a preventable disease; therefore, a better understanding of the molecular mechanisms underlying its pathogenesis and recovery processes could provide therapeutic targets for drug development and reduce the associated mortality rate. Laminarin, a polysaccharide, is a nutraceutical that can be found in brown algae. Accumulating evidence suggests that laminarin could reduce the detrimental effects of neuroinflammation on brain damage after stroke. However, the molecular mechanism underlying its beneficial effects remains largely unknown. In the present study, we used a middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomics to investigate the molecular targets and pathways involved in the beneficial effects of laminarin on ischemic stroke. Our results show the involvement of laminarin targets in biological processes related to blood circulation, oxygen supply, and anti-inflammatory responses in the normal brain. More importantly, laminarin treatment attenuated brain damage and neurodeficits caused by ischemic stroke. These beneficial effects are controlled by biological processes related to blood vessel development and brain cell death through the regulation of canonical pathways. Our study, for the first time, delineated the molecular mechanisms underlying the beneficial effects of laminarin on ischemic stroke prevention and recovery and provides novel therapeutic targets for drug development against ischemic stroke.

Introduction Ischemic stroke accounts for 70–80% of all stroke cases, leading to over two million people dying every year. Poor diagnosis and late detection are the major causes of the high death and disability rate. Methods In the present study, we used the middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomic analysis, followed by a systematic advanced bioinformatic analysis, including gene ontology enrichment analysis and Ingenuity Pathway Analysis (IPA). We aimed to identify novel biomarkers for the early detection of ischemic stroke. In addition, we aimed to delineate the molecular mechanisms underlying the development of ischemic stroke, in which we hoped to identify novel therapeutic targets for treating ischemic stroke. Results In the comparative transcriptomic analysis, we identified 2657 differentially expressed genes (DEGs) in the brain tissue of the MCAO model. The gene enrichment analysis highlighted the importance of these DEGs in oxygen regulation, neural functions, and inflammatory and immune responses. We identified the elevation of angiopoietin-2 and leptin receptor as potential novel biomarkers for early detection of ischemic stroke. Furthermore, the result of IPA suggested targeting the inflammasome pathway, integrin-linked kinase signaling pathway, and Th1 signaling pathway for treating ischemic stroke. Conclusion The results of the present study provide novel insight into the biomarkers and therapeutic targets as potential treatments of ischemic stroke.