Neuroplasticity and therapeutic
Team:
Alexandra Benchoua : Research associate (CECS)
Pauline Georges : Associated engineer (CECS)
Claire Boissart : Associated engineer (CECS)
Aurélie Poulet : Associated engineer (CECS)
Aims and background :
The term “Neuroplasticity” refers to the ability of the human brain to change as a result of one's experience. This capacity of adaptation results from the production of new neurons, the addition or removing of connections between neurons or of changes in the strength of these connections. Neuroplasticity is a key feature of the normal brain development and the basis of learning and memory. Its impairment during pregnancy or early childhood, as a result of exposition to pathogens, toxic agents or as a consequence of genetic mutations, leads to severe neurological deficits including mental retardation, autistic syndromes and some psychiatric disorders. In contrast, re-introduction of neurogenesis or stimulation of neuroplasticity in the adult brain both represent promising therapeutic avenues to improve psychiatric and neurodegenerative conditions.
In this context, human Embryonic Stem (hES) cells represent a unique tool to model the key steps governing human brain plasticity in vitro. Our team study how neural precursors are produced from pluripotent embryonic stem cells, how these Neural Stem Cells (NSC) self-renew to maintain the pool of precursors and, finally, how post-mitotic mature neurons form and connect to each others. Our goal is to identify signaling pathways which control or coordinate these different phenotypic transitions and to evaluate how these pathways can be influenced by the cellular environment, altered in pathological contexts or serve as therapeutic targets.
In this context, human Embryonic Stem (hES) cells represent a unique tool to model the key steps governing human brain plasticity in vitro. Our team study how neural precursors are produced from pluripotent embryonic stem cells, how these Neural Stem Cells (NSC) self-renew to maintain the pool of precursors and, finally, how post-mitotic mature neurons form and connect to each others. Our goal is to identify signaling pathways which control or coordinate these different phenotypic transitions and to evaluate how these pathways can be influenced by the cellular environment, altered in pathological contexts or serve as therapeutic targets.
(A) Self-renewing NSC express the cytoplasmic marker Nestin (green) and the nuclear marker Sox2 (red) (B) At day 14, fully differentiated neurons form complex networks (neurites in white) and functional synapses (pre-synaptic synapsine in red, post-synaptic PDS95 in green, synapses in orange).
Strategy, means and methods :
We use hES cells as a source of pluripotent cells to understand how the decision of neural commitment is taken and synchronized. Once the neural lineage established, the resulting NSC provide the starting material to study self-renewal or to produce human neurons in vitro and follow in real-time their maturation and connections into complex networks. The adaptation of these culture systems to miniaturized formats suitable for high and medium throughput screenings and the development of image-based automated analysis to reveal any alteration of each phenotypic transition raise the possibility to interfere with these systems by any means (small molecules, FDA approved marketed drugs, nucleic acids) and evaluate the consequences on both neurogenesis and neuroplasticity.
(C) Time course of differentiation and maturation of NSC-derived neurons
Results and future prospects :
One main achievement of our team was the development of a genuine protocol which allows the formation of neural tube-like structures in vitro in a synchronized and homogeneous manner. This system was used to identify micro-RNAs involved in the process of neural commitment. More technically, the very high efficiency of this system allowed the isolation and expansion of NSC in a standardized manner and qualified NSC for industrial purposes. We have defined the culture conditions necessary to maintain these cells as an adherent homogeneous self-renewing population and characterized their potential to produce functional embryonic neurons. The neuronal differentiation protocol was miniaturized in a 384 well plate screening format and several tests were developed to analyze in an automated manner different aspects of neurogenesis and neuroplasticity using the Cellomics™ Array-scan platform.
This screening model was validated during our collaboration with the pharmaceutical group Roche and will be, in the future, used to identify key signaling pathways involved in neuroplasticity and study their involvement in different pathological contexts (CMV infection, disease-related genetic mutations ect…).
Patent :
WO/2010/063848 (2010-06-10)
BENCHOUA, Alexandra; (FR). PERRIER, Anselme; (FR). AUBRY, Laetitia; (FR).
Method and medium for neural differentiation of pluripotent cells.
BENCHOUA, Alexandra; (FR). PERRIER, Anselme; (FR). AUBRY, Laetitia; (FR).
Method and medium for neural differentiation of pluripotent cells.
Collaborations :
Pr. Austin G Smith, The Wellcome Trust Centre for Stem Cell Research, Cambridge, UK (Neural stem cells biology)
Dr. Stéphane Chavanas, Inserm U563, Toulouse, France (Cytomegalovirus induced Neuropathology )
Dr. Stéphane Jamain, IMRB, Inserm U955, Créteil, France (Early Onset Bipolar disorders)
Dr. Sannah Jensen Zoffmann and Dr Martin Graf, Pharmaceutical Division, Discovery Technologies, F.Hoffmann-Laroche Ltd, Basel, Switzerland (Roche/ISTEM collaboration, PROWIN program) 