Neuroprotective agents(Shenyang University of Chemical Technology)

Endovascular thrombectomy has a recanalization rate over 80%; however, approximately 50% of ischemic stroke patients still experience dependency or mortality. Recently, clinical trials demonstrated the benefits of administering neuroprotective agents prior to endovascular thrombectomy. Additionally, recent studies showed neuroprotective effects of mild hypercapnia in patients resuscitated after cardiac arrest. However, its efficacy in ischemic stroke remains unclear. We aimed to investigate whether carbon dioxide (CO 2 ) per-conditioning has neuroprotective effects in rat models with middle cerebral artery occlusion (MCAO). Rat models received intermittent inhalation of mixed gas during the MCAO period. After surgery, behavioral assessments, infarct size measurement, immunohistochemistry, and western blot analysis were performed. We found CO 2 per-conditioning reduced infarct size and neurological deficit. The number of 8-hydroxy-2-deoxyguanosine (8-OHdG) positive cells and matrix metalloproteinase 9 (MMP-9)/platelet derived growth factor receptor beta (PDGFRβ) double positive cells were significantly decreased after CO 2 per-conditioning. The expressions of tight junction protein and pericytes survival were preserved. This study underscores mild hypercapnia before reperfusion not only reduces neurologic deficit and infarct size, but also maintains the integrity of the blood-brain barrier and neurovascular unit, alongside mitigating oxidative stress in hyperacute stroke rat models. Therapeutic mild hypercapnia before reperfusion is promising and requires further clinical application.

Repurposing drugs for neurodegenerative diseases using the nose-to-brain route of administration is an intriguing concept with potential benefits. The nose-to-brain route involves delivering drugs directly to the brain via the olfactory or trigeminal pathways, bypassing the blood-brain barrier, which can improve drug efficacy and reduce systemic side effects. Treatment of numerous neurodegenerative diseases such as Multiple sclerosis, Amyotrophic lateral sclerosis, Huntington's, Alzheimer's, and Parkinson's diseases has been attempted using this route of administration. These drugs may include neuroprotective agents, anti-inflammatory drugs, antioxidants, or diseasemodifying therapies. Nanotheranostics, which integrates therapeutic and diagnostic functions in a nanosystem, improves treatment precision and efficacy. Repurposing nanotherapeutics as nanotheranostics for neurodegenerative diseases through the nose-to-brain route of administration holds great potential for both diagnosis and treatment. This review highlights the various mechanisms engaged in transporting nanocarriers from nose-to-brain and the proposed fate of these nanocarriers using different live imaging techniques. Additionally, the discussion covers the recent combinatorial therapeutic approaches and theranostic applications of various nanocarriers used for neurodegenerative diseases through the nose-to-brain. Toxicity to the CNS and nasal mucosa and regulatory considerations about these delivery systems are also deliberated. Overall, repurposed nanoparticles designed as nanotheranostic agents offer a versatile platform for precise diagnosis, targeted therapy, and personalized management of neurodegenerative diseases, holding great promise for improving patient care and advancing our understanding of these complex disorders.