PhD Scientific Days 2025

Poster Session II. - J: Theoretical and Translational Medicine

Functional and electrophysiological analysis of aging in induced neurons reprogrammed from adult human dermal fibroblasts

Name of the presenter

Kis Balázs

Institute/workplace of the presenter

Institute of Translational Medicine

Authors

Balázs Kis¹, Melinda E. Gazdik^1,2, Anikó Göblös³, Roger A. Barker⁴, Lajos Kemény³, Attila Szűcs^2,5, Karri Lamsa⁶, Karolina Pircs^5,7

1: HCEMM-SU Neurobiology and neurodegenerative diseases, Institute of Translational Medicine, Semmelweis University, Budapest, Hungary.
2: Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary
3: HCEMM-USZ, Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary
4: Wellcome-MRC Cambridge Stem Cell Institute & John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
5: HCEMM-SU Neurobiology and neurodegenerative diseases, Institute of Translational Medicine, Semmelweis University, Budapest, Hungary
6: HCEMM-USZ, Human neuron physiology and therapy Core Group, Szeged, Hungary
7: Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem

Text of the abstract

It is challenging to study human specific functional properties during physiological aging in human neurons due to accessibility. Neurons from model species show similarities to human neurons, but the latter display unique electrophysiological characteristics, like distinct input resistance and action potential threshold voltage. We aim to develop a robust system that will enable reliable, high throughput functional characterization of aged human neurons for drug-screening.
We use an inducible lentiviral system which consists of a doxycycline driven transactivator coupled to a transcription factor ASCL1. This enables us a highly efficient way to reprogram human dermal fibroblasts into induced neurons (iNs). During the transdifferentiation, cells do not go through a pluripotency. iNs keep the genetic and epigenetic aging signature of the donors. This makes iNs uniquely adequate to study aging and age-related diseases from a functional perspective.
We started to optimize the transdifferentiation methodology to whole-cell patch-clamp recordings coupled with current-step measurements. We identified 3 subpopulations in iNs after 25 days of conversion: (i) non-differentiated cells with no neuron like membrane potential, (ii) differentiated-passive cells with neuron like membrane potential, and (iii) differentiated cells with rectification of injected current and spikelets. We are currently repeating our recordings to further optimize our system by increasing the cellular density to engage synapse formation and by optogenetic training expressing ChR2-channel rhodopsin in the iNs. After successfully defining the best culturing conditions, we plan to study functional differences in iNs derived from young and old donors. Identifying age-related electrophysiological changes such as ion-channel response, action potential shape, duration, and membrane potential will be an important step to understand healthy and non-healthy aging and give us potential targets for intervention.