Magnetic Iron Oxide Nanoparticles and Brain Ubiquitin Expression in Hyperthermia

Functionalized magnetic iron oxide nanoparticles (FMIONPs) are used for cancer therapy together with whole body hyperthermia (WBH) or for drug delivery to the target tumor tissues using external magnetic guidance. Our laboratory has previously shown that FMIONPs are innocuous in normal healthy rats up to 24 h, however, when administered following WBH an exacerbation of brain pathology occurs. Interestingly, when TiO2 nanowired Cerebrolsyin is delivered together with FMIONPs in WBH significant neuroprotection is seen. However, the detailed mechanisms of cerebrolysin-induced neuroprotection are still unclear. The present investigation was undertaken to explore the possible mechanisms of cerebrolysin-induced neuroprotection in FMIONPs induced brain pathology in WBH. Cerebrolsyin is a balance composition of several neurotrophic factors and active peptide fragments. Thus, a possibility exists that TiO2 nanowired Cerebrolsyin could attenuate cellular stress responses following WBH together with FMIONPs administration. We used ubiquitin and heats shock protein (HSP) 72 kD to evaluate stress responses in WBH and FMIONPs combination. Young adult Male Sprague Dawley rats (age 25 to 27 weeks) were administered FMIONPs in a dose of 0.50 mg/mL in100 µl intravenously and then subjected to 4 h WBH at 38°C in a Biological Oxygen Demand (BOD) Incubator (relative humidity 45-47 % and wind velocity 20-22 cm/sec). Twenty-four h after WBH immunohistochemistry of Ubiquitin and HSP 72 kD were examined on paraffin sections from the brain passing thorough parietal cerebral cortex and hippocampus. In a separate group rats, TiO2 nanowired Cerebrolsyin (2.5 ml/kg) was also co-administered and the brains were processed under identical conditions for ubiquitin and HSP-72 kD immunoreactivity. In addition, albumin immunoreactivity was also assessed to test any breakdown of the blood-brain barrier (BBB) to the endogenous serum proteins. Our observation show that FMIONPs following WBH resulted in pronounced albumin leakage and upregulation of ubiquitin and HSP immunoreactivity in the cerebral cortex, hippocampus, hypothalamus and thalamus. Interestingly TiO2 nanowired Cerebrolsyin (2.5 ml) exhibited significant reduction (> 90%) in albumin, ubiquitin and HSP immunoreaction in the brain after FMIONPs treatment following WBH. Taken together our results for the first time show that FMIONPs induces enhanced stress reaction in the brain following WBH and TiO2 cerebrolysin treatment reduces these stress signals significantly indicating a potential role of Cerebrolysin in reducing brain pathology in cancer patients where FMIONPs are used as an adjunct therapy.