Periodic Reporting for period 4 - ProNeurons (Transcription Factor-mediated Neuronal Cell Fate Programming in Human Stem Cells)
Berichtszeitraum: 2020-09-01 bis 2021-02-28
The use of human induced pluripotent stem cells (hiPSCs) facilitates studying the genesis of human cell types in an ethically approved setting. However, exploiting the full potency of stem cells is only possible with very few differentiated cell types. In particular, the generation of neurons is in its infancy: of the many neuronal types present in the brain, only very few of the more than 300 cell types have been generated in vitro. So far, neuronal differentiation protocols are multifaceted and tailored to individual cell types. The molecular events that occur during reprogramming remain enigmatic. Hence, we cannot confer these protocols easily on producing different neurons of interest. The idea of these ERC actions was to induce transcription factors (TFs) as differentiation control buttons in hiPSCs and to explore their potency to trigger in vitro neurogenesis systematically.
Although highly important for biomedical research, there is a steady increasing societal pressure to reduce and to ban research using animal models. Therefore, programming certain human neuronal cell types from hiPSCs in high quality and quantity might substitute for some research that currently requires animal experimentation. These hiPSC-derived neurons represent potent model systems to study human pathologies but also basic cellular functions in a dish. In addition, differentiated human neurons such as photoreceptors for retinal degenerative diseases or dopaminergic neurons for Parkinson disease are of high interest for cell replacement therapies to repair vision and brain function.
All major objectives of the ProNeurons ERC actions were accomplished. A comprehensive human TF library was established and used for efficient forward programming of hiPSC to neurons (Ng, Khoshakhlagh et al. Nature Biotech 2020). Of particular interest was the discovery of three TFs that drive hiPSCs to photoreceptor precursor cells in just ten days in high efficiencies. These cells are currently evaluated as source material for transplantation therapies. Induced neurons were functionally, transcriptomically and anatomically characterized (Kutsche et al. Cell Systems 2018 and (Ng, Khoshakhlagh et al. Nature Biotech 2020). We have also developed and prototyped novel bioinformatic analyses to study the dynamically changing transcriptome from stem cell to neuron. Thereby, we could reveal the molecular blue prints of cell conversions (Kutsche et al. Cell Systems 2018).
Although highly important for biomedical research, there is a steady increasing societal pressure to reduce and to ban research using animal models. Therefore, programming certain human neuronal cell types from hiPSCs in high quality and quantity might substitute for some research that currently requires animal experimentation. These hiPSC-derived neurons represent potent model systems to study human pathologies but also basic cellular functions in a dish. In addition, differentiated human neurons such as photoreceptors for retinal degenerative diseases or dopaminergic neurons for Parkinson disease are of high interest for cell replacement therapies to repair vision and brain function.
All major objectives of the ProNeurons ERC actions were accomplished. A comprehensive human TF library was established and used for efficient forward programming of hiPSC to neurons (Ng, Khoshakhlagh et al. Nature Biotech 2020). Of particular interest was the discovery of three TFs that drive hiPSCs to photoreceptor precursor cells in just ten days in high efficiencies. These cells are currently evaluated as source material for transplantation therapies. Induced neurons were functionally, transcriptomically and anatomically characterized (Kutsche et al. Cell Systems 2018 and (Ng, Khoshakhlagh et al. Nature Biotech 2020). We have also developed and prototyped novel bioinformatic analyses to study the dynamically changing transcriptome from stem cell to neuron. Thereby, we could reveal the molecular blue prints of cell conversions (Kutsche et al. Cell Systems 2018).
Following results have been achieved within the ProNeurons ERC actions:
1. We can systematically program hiPSCs to neurons using the developed transcription factor library.
2. We improved the chemistry of single cell RNA Sequencing to simultaneously detect the overexpressed (neuronal differentiation inducing) transcription factors and the neuronal cell identity in one reaction.
3. We are now able to bioinformatically analyze the molecular rules of in vitro neurogenesis.
4. Many human neuronal subtypes have been generated that have a broad basic but also biomedical impact in the life science field.
5. The photoreceptor precursor cells have the potential to become the donor source for photoreceptor transplantation therapies to overcome blindness.
These results have been published in scientific journals and were communicated to the scientific and industrial audiences by all team members at international conferences and workshops. Several aspects have been covered by international media including newspapers and social media. The exploitation of the results is still ongoing. A patent application for the photoreceptor differentiation protocol has been filed and is currently evaluated. This part will be further exploited within the ERC PoC iPhotoreceptor actions.
1. We can systematically program hiPSCs to neurons using the developed transcription factor library.
2. We improved the chemistry of single cell RNA Sequencing to simultaneously detect the overexpressed (neuronal differentiation inducing) transcription factors and the neuronal cell identity in one reaction.
3. We are now able to bioinformatically analyze the molecular rules of in vitro neurogenesis.
4. Many human neuronal subtypes have been generated that have a broad basic but also biomedical impact in the life science field.
5. The photoreceptor precursor cells have the potential to become the donor source for photoreceptor transplantation therapies to overcome blindness.
These results have been published in scientific journals and were communicated to the scientific and industrial audiences by all team members at international conferences and workshops. Several aspects have been covered by international media including newspapers and social media. The exploitation of the results is still ongoing. A patent application for the photoreceptor differentiation protocol has been filed and is currently evaluated. This part will be further exploited within the ERC PoC iPhotoreceptor actions.
Within the stem cell programming field, the unbiased TF library is a huge step forward and a breakthrough to generate cell types of interest. These human cell lines will serve as human testbeds and are likely complementary to animal research in basic and biomedical sciences. The systems level in-depth analyses of the in vitro neurogenesis also goes beyond the state and demonstrates clearly the necessity of applied and computation sciences to understand and thereby control developmental processes starting from stem cells. The genetic recipe to engineer photoreceptors from human stem cells is a breakthrough for the retinal research community especially for the photoreceptor transplantation field. The ERC actions will lead to generating photoreceptors rapidly in high quantity and quality.