The focus of my research over the past 10 years has been the question how stem cell technology can be harnessed to understand the function and dysfunction of neural circuits that control motor behaviour, and how human stem cell-derived circuit models can be used to identify pharmacological and genetic treatments that restore motor function in degenerative and neurodevelopmental disorders. To this end, my group is undertaking projects aimed at assembling neuromuscular circuits from stem cell-derived, defined cell populations to study normal neural development and degenerative disease processes in vitro such as Amyotrophic Lateral Sclerosis (ALS). More recently, we have expanded these efforts to modelling cortical circuits with human induced pluripotent stem cell (hiPSC)-derived neurons and glia, with the aim of studying diseases that affect the motor areas of the cortex, likeFrontotemporal Dementia (FTD), which shares disease mechanisms and molecular pathology with ALS.

Postdoctoral Research Associates

• Federica Ricco
• Laura Kleckner

PhD Students

• Caoimhe Goldrick
• Hannah Casbolt

Our Partners

• Prof Wenhui Song, UCL – Polymer Engineering
• Prof Juan Burrone, KCL – Electrophysiology, Optogenetics
• Dr Yung-Yao Lin, QMUL – Muscular Dystrophy
• Prof Virgile Viasnoff, MBI/NUS - Microdevices

Projects

One of the key limitations of current neuromuscular disease models is the lack of scalable in vitro culture systems that recapitulate complex disease phenotypes, andincorporate nerve-muscle connectivity. A significant engineering challenge has been stabilizing mature contractile myofibers in a scalable multi-well format suitable for drug screens. In 2D cultures, contractile myofibers detach from the rigid tissue culture plate surface, precluding longitudinal phenotypic analysis. Most 3D solutions to this problem have involved suspending bundles of myofibers between flexible micropillars, but the scalability of these approaches and amenability to automated analysis has been limited. In collaboration with the material scientist Prof Wenhui Song (UCL), my group has developed elastomer nanofiber scaffolds which stabilize hiPSC-derived contractile nanofibers for culture periods of several weeks, and allow repeated optogenetic stimulation without myofiber collapse (ref 4). We have recently adapted this culture system to a multi-well plate format compatible with high content imaging, and we have shown that microdevices co-cultures of hiPSC-myofibres and motor neurons recapitulate ALS-related synaptic and functional phenotypes, which can be rescued with a known candidate drug. We plan to use this culture system to systematically test treatments on human neuromuscular circuits with authentic ALS genotypes, and define their cellular target population.

To complement the technology development of neuromuscular microdevices, my group teamed up with the neurophysiologist Prof. Juan Burrone (KCL) to investigate the role of hyperexcitability in ALS. In vitro and in vivo models of ALS/FTD have established that, in addition to synaptic changes at the neuromuscular junction, dysregulation of neuronal excitability is a key feature of the disease. We have shown that motor neurons generated from patient-derived hiPSCs with TDP-43 or C9orf72 mutations are hyperexcitable due to an extension of the axon initial segment and a loss of compensatory forms of plasticity that are typically engaged in hyperactive networks. Consistent with their increased activity, TDP-43 mutant hiPSC-motor neurons trigger spontaneous myofiber contractions when co-cultured with uniformly aligned myofibers in neuromuscular devices, a phenotype which mirrors muscle fasciculations in patients with ALS during the early clinical phase of the disease. We will build on these initial findings and test if normalization of neural activity in hiPSC-motor neurons with small molecule compounds, antisense oligonucleotides or gene therapy vectors can prevent or reverse cellular pathology in human neuromuscular circuit models.