Delayed luminescence for in vitro study of mitochondrial dysfunctions in neurodegenerative diseases

Spectroscopic studies of Delayed Luminescence emitted by an in vitro model for studying of the effects of amyloid-βeta (Aβ) have been performed. Aβ is a neurotoxic protein overexpressed in Alzheimer's Disease (AD), which is also related to mitochondrial dysfunction. The experiments have been carried out on primary Olfactory Ensheathing Cells (OECs) cultures. Cells have been exposed to Aβ(1-42) native full-length peptide or to Aβ(25-35), a toxic fragment of Aβ, or Aβ(35-25), a non toxic Aβ fragment, both in absence and in presence of Astaxanthin, a well-known antioxidant agent. To monitor cell viability, MTT test was used. Reactive oxygen species and reduced glutathione levels were utilized to test the oxidative intracellular status. We also assessed the expression of some glial markers (Glial Acidic Fibrillary Protein, Vimentin), of Nestin, stem cell marker, and the activation of the apoptotic pathway assessing caspase-3 cleavage. We found that, in OECs, Glial Acidic Fibrillary Protein, Vimentin expression and caspase-3 exhibited a significant enhancement in Aβ(1–42) and Aβ(25–35) exposed cells. The pre-treatment with Astaxanthin restored the levels of Vimentin and caspase-3 to control values, increasing also Nestin expression levels and reestablished the intracellular oxidative status modified by the exposure to Aβ(1–42) or Aβ(25–35) of OECs. DL intensity and kinetics changes as a function of the treatments were also measured. In particular, an increase in DL emission, with respect the untreated cells (controls), was observed in cells exposed to Aβ(25-35) fragment. This emission appeared quenched in presence of Astaxanthin.