Measuring the circuit integration of hPSC-derived dopaminergic neurons with optogenetic-fMRI
Description: Human pluripotent stem cell (hPSC) replacement therapy has been proposed as a promising avenue in regenerative medicine, having the potential to address neurological and neurodegenerative illnesses that now lack viable therapeutic choices. In recent years, researchers have made significant progress in differentiating, cryopreserving and transplanting highly pure mesencephalic dopaminergic neurons (mesDA) from hPSCs, paving the way for the development of a breakthrough therapy for Parkinson's disease (PD), which specifically targets mesDA-neuronal loss. Several Phase I trials leveraging this therapy are currently ongoing in the US, Europe and Japan, making it the first potential disease-modifying treatment for this debilitating condition. An important aspect of the current approach is its focus on increasing dopamine availability in the dorsal striatum supplied by the grafted cells. While this strategy offers promise in ameliorating motor-related symptoms in PD, additional research is needed to evaluate the feasibility of hPSC-derived cell transplantation as a circuit-repair intervention. The central hypothesis of this proposal is that graft cells must establish extensive functional connections with pertinent downstream regions (i.e., the natural targets of the host cells they are intended to substitute) to be deemed fully integrated into native tissue and play a pivotal role in repairing damaged circuits. Recent studies have made progress in addressing this challenge, demonstrating that circuit-integration of hPSC-derived organoids is possible when the transplantation is performed in the early postnatal period, allowing for an optimal window of opportunity for cell growth and integration. These findings are exciting and offer hope for future development of hPSC replacement therapies. However, critical challenges still remain in the field: how to quantify the functional role that grafted cells take on after transplantation and how to assess their circuit-integration in the host tissue in vivo and non-invasively? Without this understanding, the potential of cell replacement therapy to address human disorders linked to brain circuits breakdown remains severely limited. To address this critical shortcoming, I will pioneer a new experimental strategy in rats that entails testing an hPSC replacement therapy in conjunction with optogenetics and functional MRI to measure the functional circuit integration of hPSC-derived mesDA cells in vivo, longitudinally, and across the entire brain. This approach stands out from conventional electrophysiological or imaging techniques in multiple ways. Notably, it provides a unique opportunity to examine brain-wide responses to hPSC-derived mesDA cell activation, offering an unparalleled level of insight into the long-range functional connections formed over time by these implanted cells. Furthermore, opto-fMRI monitoring is minimally invasive, and with recent advances in awake imaging, animals can be scanned multiple times over several months after cell transplantation without repeated anaesthesia. This will allow us to characterize the entire graft integration process as well as system-level plasticity in unprecedented detail. In summary, the proposed experimental approach has the potential to boost the field of regenerative medicine, offering a new way to quantify the functional integration of grafted cells in the host tissue in vivo, longitudinally, and minimally-invasively. Because of its cutting-edge nature, the project does carry some risks. However, these are related to the lack of knowledge about the functional integration of the implanted cells that will be uncovered here, rather than the feasibility or implementation of each proposed experimental part. By characterizing the range and magnitude of functional responses, we can gain a deeper and quantitative understanding of the spatio-temporal integration of cell replacement in an animal model relevant for human translation. This notion has strong implications for studying the factors that drive the effectiveness and success of cell replacement therapies.
Amount: CHF 99,940
Funding type: grant
Funder scheme: Spark
Start date: 2024-04-01
End date: 2026-03-31
Investigator: Zerbi, Valerio
Institution: University of Geneva – GE
Subfield: Molecular Biology
Domain: Life Sciences
Funded outputs count: 0
Funder award ID: 221191
OpenAlex ID: G5654314186