Periodic Reporting for period 1 - 4F4REJUVENGLIA (4F-induced rejuvenation of glia into neural stem cells for brain repair)
Période du rapport: 2019-05-01 au 2021-04-30
Human life expectancy has increased more than two-fold over the past two centuries, resulting in a dramatic increase in the elderly population. Advanced age is associated with physiological decline, which ultimately lead to an enhanced predisposition to diseases. Aging is the highest risk factor for neurodegenerative diseases. Remarkably, Alzheimer disease and other dementias are among the most common causes of death. The World Health Organization reported that up to 1 billion people, nearly one in six of the world’s population, suffer from neurological diseases, which make these disorders a growing burden for aged societies worldwide (1).
Many of these neurological disorders have in common the malfunction of neurons, but most neurons are not replaced during normal life or pathological situations. The formation of neurons or neurogenesis is rare in postnatal life, and only occurs in two confined areas of the mammalian brain. Because adult neurogenesis is limited, the regenerative capacity of the brain is restrained and the possibilities of recovery from damage are almost absent. Current clinical interventions for neurological dysfunction are very limited, highlighting the need for strategies to palliate the loss of functional neurons occurring in these conditions.
This project, 4F4REJUVENGLIA (short for: 4 Factors for rejuvenating glia)focuses on a novel approach to address regeneration in the nervous system, based on nuclear cell reprogramming technology, to generate new neurons in regions naturally devoid of neurogenesis. Current methods of reprogramming use direct conversion from glial cells to neurons by the expression of proneural factors I proposed an alternative approach, partial reprogramming, based in the short expression of the Yamanaka factors, to facilitate the conversion from glia to neuron through an intermediate progenitor state. We hypothesise that this “rewinding” to a neural progenitor-like state may rearrange the local environment and remodel it towards a stem cell niche that help instruct and integrate new neurons within the preexisting circuits.
The project is guided by the objective of harnessing the potential offered by cell reprogramming technology to manipulate tissue regeneration and explore its applications to promote brain repair. The strategy is to use reprogramming to reinstall neurogenesis in brain areas, such as the cerebral cortex, which are naturally devoid of neurogenesis once embryogenesis is completed. The formation of new neurons aims to compensate for the degeneration of these cells occurring in pathophysiological conditions and to promote the regeneration of damaged brain areas.
Many of these neurological disorders have in common the malfunction of neurons, but most neurons are not replaced during normal life or pathological situations. The formation of neurons or neurogenesis is rare in postnatal life, and only occurs in two confined areas of the mammalian brain. Because adult neurogenesis is limited, the regenerative capacity of the brain is restrained and the possibilities of recovery from damage are almost absent. Current clinical interventions for neurological dysfunction are very limited, highlighting the need for strategies to palliate the loss of functional neurons occurring in these conditions.
This project, 4F4REJUVENGLIA (short for: 4 Factors for rejuvenating glia)focuses on a novel approach to address regeneration in the nervous system, based on nuclear cell reprogramming technology, to generate new neurons in regions naturally devoid of neurogenesis. Current methods of reprogramming use direct conversion from glial cells to neurons by the expression of proneural factors I proposed an alternative approach, partial reprogramming, based in the short expression of the Yamanaka factors, to facilitate the conversion from glia to neuron through an intermediate progenitor state. We hypothesise that this “rewinding” to a neural progenitor-like state may rearrange the local environment and remodel it towards a stem cell niche that help instruct and integrate new neurons within the preexisting circuits.
The project is guided by the objective of harnessing the potential offered by cell reprogramming technology to manipulate tissue regeneration and explore its applications to promote brain repair. The strategy is to use reprogramming to reinstall neurogenesis in brain areas, such as the cerebral cortex, which are naturally devoid of neurogenesis once embryogenesis is completed. The formation of new neurons aims to compensate for the degeneration of these cells occurring in pathophysiological conditions and to promote the regeneration of damaged brain areas.
The project was organised in four main aims for the whole duration of this project. The first and more important aim was the generation of an in vivo aproach that allows me to induce reprogramming specifically in glial cells. During the year that this project has run, I have been able to generate two mouse models to this end. I developed a model that expresses the reprogramming factors in response to doxycycline in specific cells when is combined with adeno associated viral vectors, and a second model that induce the reprogramming factors in response to doxycycline in astroglia without the need of viral vectors. These two models will be useful to investigate different induction patterns in distinc glial cell populations. Although at the design phase of this project I planned just to study the effect of the Yamanka factors on the conversion of glia into induced neurons, soon I realised that I could learn about the cell identity switch mechanism using also other reprogramming technology called direct reprogramming or lineage reprogramming in which the host laboratory have extensive experience. This approach use proneural transcription factors to promote the conversion of glia directly into neurons, insted of the pluripotent Yamanka factors. With this goal, during this year I developed an in vitro phenotyping platform to scrutinise the importance of molecular players on the adquisition of neuronal phenotype during direct reprogramming from astrocyte-to-neuron using Neurogenin2 as the proneural factor.
Although I couldn´t complete the entire project in this first year, the advances made in the generation of the animal models have allowed me to apply for further funding and start my independent career as junior principal investigator at University of Seville.
The reprogramming toolbox developed under the umbrella of this project, including the animal models and the in vitro phenotyping platform, will allow me to continue my investigation to understand the mechanisms and barriers to exploit reprogramming as a therapeutic tool for CNS regeneration
The reprogramming toolbox developed under the umbrella of this project, including the animal models and the in vitro phenotyping platform, will allow me to continue my investigation to understand the mechanisms and barriers to exploit reprogramming as a therapeutic tool for CNS regeneration