| Popis |
Introduction: Amyloid-ß (Aß) oligomers are implied to enhance excitability and cause irreversible neural alterations. Such activity appears in preclinical stages of AD, particularly in the hippocampus, which also contributes to epileptogenic loci in temporal epilepsy. By investigating electrical changes in Alzheimer’s-like cerebral organoid models, we are recreating the microenvironment corresponding to the substrate from which epileptogenic activity emerges. Main aim: To examine the effect of neurodegenerative marker accumulation on neuronal excitability in Alzheimer's models. Methods: Electrical activity was measured in vitro at 37°C by the multielectrode array technique in cerebral organoids, derived from hiPSCs of a patient with a familial form of AD (n = 15) and an unrelated healthy control (n = 16), during differentiation days (DD) DD57-DD140. The analysis was performed on bursts detected between 5. - 15. minute of the recording. To investigate the neuronal connectivity, the global synchrony index was estimated from detected spikes. Aß concentrations were measured at DD60, DD90, and DD120 using ELISA, with Aß42/40 ratio used for the analysis. Three measurement runs were arranged by differentiation day (DD) for Aß42/40 levels and activity correlation. Normal distribution was rejected using the Shapiro-Wilk test. The significance of differences among samples was verified using the Mann-Whitney or Wilcoxon tests. The correlation between parameters was evaluated using Spearman’s rank-order method. Results: An elevation in electrical activity was observed in AD, especially in metrics such as the percentage of active electrodes (WT 1.7 vs. AD 18.7 %, P < 0.001), global synchrony index (WT 0.34 vs. AD 0.39, P < 0.001), intraburst spike number (WT 6.75 vs. AD 10.63, P < 0.001), intraburst spike frequency (WT 37.2 vs. AD 41.7 Hz, P < 0.001), and burst duration (WT 0.20 vs. AD 0.24 s, P < 0.05). In two out of three recorded runs, the Aß42/40 was elevated in AD, specifically at DD120 (WT 0.029 vs. AD 0.070, P < 0.05). Furthermore, a significant increase in Aß42/40 of AD was observed between DD60 and DD90 (DD60: 0.062 vs. DD90: 0.070, P < 0.01). A strong correlation between Aß42/40 ratio and activity parameters was found in AD, whereas the correlation with activity parameters in WT was not significant, e.g. Aß42/40 vs. intraburst spike number (AD: rs = 0.7782, P < 0.05), or Aß42/40 vs. intraburst spike frequency (AD: rs = 0.7333, P < 0.05). Conclusion: The findings indicate that AD organoids exhibit an increase in spontaneous electrical activity compared to controls, alongside a significant increase in Aß42/40 ratio correlating with this activity. This suggests a potential association between the Aß42/40 ratio and neuronal excitability, warranting further exploration of these relationships.
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