: In stroke (brain ischemia), the leading cause of functional disability and mortality worldwide, despite continuous efforts both at experimental and clinical level in getting the better understanding, the only approved pharmacological treatment has been restricted to tissue plasminogen activator (tPA). Its complex pathophysiology starts with energy pump failure which ends with neuronal cell death. Ischemic cascade involves excessive glutamate release followed by raised intracellular sodium and calcium influx along with free radicals’ generation, activation of inflammatory cytokines, NO synthases, lipases, endonucleases and other apoptotic pathways leading to cell edema and death. At pre-clinical stage, several agents have tried and proven as an effective neuroprotectant in animal models of ischemia. However, these agents failed to show convincing results in terms of efficacy and safety when the trials were conducted in humans following stroke. This article highlights the various agents which have tried in the past but failed to translate into stroke therapy along with key points that are responsible for lagging of experimental success to translational failure in stroke treatment.

Drug repurposing (or drug repositioning) is an innovative way to find out the new indications of a drug that already exists in the market with known therapeutic indications. It offers an effective way to drug developers or the pharmaceutical companies to identify new targets for FDA-approved drugs. Less time consumption, low cost and low risk of failure are some of the advantages being offered with drug repurposing. Sildenafil (Viagra), a landmark example of a repurposed drug, was introduced into the market as an antianginal drug. But at present, its use is repurposed as drug for erectile dysfunction. In a similar way, numerous drugs are there that have been successfully repurposed in managing the clinical conditions. The chapter would be highlighting the various drug repurposing strategies, drugs repurposed in the past and the current status of repurposed drugs in the orphan disease therapeutics along with regulatory guidelines for drug repurposing.

Aim: The aim of the study was to evaluate the neuroprotective effect of bone marrow stem cell secretome in the 6-hydroxydopamine (6-OHDA) model of Parkinson's disease. Materials & methods: Secretome prepared from mesenchymal stem cells of 3-month-old rats was injected daily for 7 days between days 7 and 14 after 6-OHDA administration. After 14 days, various neurobehavioral parameters were conducted. These behavioral parameters were further correlated with biochemical and molecular findings. Results & conclusion: Impaired neurobehavioral parameters and increased inflammatory, oxidative stress and apoptotic markers in the 6-OHDA group were significantly modulated by secretome-treated rats. In conclusion, mesenchymal stem cells-derived secretome could be further explored for the management of Parkinson's disease.

Background: The aryl hydrocarbon receptor (AhR) mediated signaling pathway is being emerged as a current target for neuromodulation. The present study was conducted to characterize the neuroprotective action of AhR modulators, i.e., 3,3′-diindolylmethane (DIM) and ɑ-naphthoflavone (ANF) in an experimental model of stroke using transient middle cerebral artery occlusion (MCAO) in Wistar rats. Methods: The animals were treated with respective AhR modulators via intraperitoneal (i.p) injection 3 hrs after MCAO for 4 days (at 24 h interval). Following transient MCAO, the brain infarct volume, ND scoring, and various neuro behavioural tests were conducted to confirm the ischemic stroke. Further, oxidative stress parameters, inflammatory cytokines, and apoptotic mRNA expression were assessed. The histopathological changes in the brain of the rats were assessed using H&E staining and the results obtained were correlated with the molecular parameters. Results: Treatment with AhR modulators had significantly decreased the brain infarct volume, ND scoring and improved neuro-behivoral deficits in animals following MCAO. A significant decrease was also observed in the oxidative stress, pro-inflammatory cytokines, and apoptotic mRNA expression in the AhR ligand treated groups. Moreover, a significant improvement was observed in the neuronal damage following MCAO in the treatment groups. Conclusion: AhR pathway modulation may be taken as a valuable therapeutic target for treating acute ischemic stroke (AIS).

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