In contrast to the use of human embryonic stem cells, there are no ethical concerns regarding the molecular reprogramming of differentiated human cells into induced pluripotent stem cells (iPS). The lentiviral reprogramming of human neonatal cord blood cells into iPS has been established recently at the MHH (AG Prof. Martin, REBIRTH) and shows a great clinical potential. In a current project, we have developed efficient strategies for the directed neuronal differentiation of these iPS into specific phenotypes (dopaminergic and GABAergic neurons, see figure 1 below).
In respect to a clinical application of iPS-derived neurons in degenerative diseases, a detailed knowledge of essential cell properties like ion channel function is indispensable. Currently, we investigate neurons generated from human iPS in respect to their voltage- and ligand-gated ion channel function and subunit expression by whole-cell patch clamp recordings and calcium-imaging (see figure 2 below). Furthermore, we plan to transplant differentiated neuronal cells in animal models of Parkinson`s disease, Amyotrophic Lateralsclerosis and epilepsy.
In three other projects, we started to differentiate and characterize iPS derived from patients with rare neurodegenerative diseases (Chorea-Acanthocytosis, Amyotrophic Lateralsclerosis (SOD1/FUS-mutations), Cerebral Lipofuscinosis) in order to gain insight into the functional and molecular pathophysiology (see figure 3 below).
Left: Differentiated human iPSC (control cell line) show the expression of the neuronal marker TUJ1 (green) and the motoneuron marker SMI32 (red) suggesting the maturation of many motoneurons, the target cells for functional analyses. Nuclei are counterstained with DAPI (blue), scale bar 20 µm.
Right: Differentiated iPSC derived from a ChAc patient show the expression of the neuronal marker TUJ1 (green) and the neurotransmitter GABA (red) suggesting the maturation of numerous GABAergic neurons. Nuclei are counterstained with DAPI (blue), scale bar 30 µm.