(F1251) TOWARDS ENHANCING CELL REPLACEMENT THERAPIES FOR PARKINSON’S DISEASE – A NOVEL APPROACH FOR ASSESSING CLONAL EXPANSION AND GRAFT DIVERSIFICATION
Abstract: Human pluripotent stem cell-based therapies are emerging as a promising treatment for Parkinson’s disease (PD), with ongoing clinical trials demonstrating the feasibility of targeted regenerative approaches. A significant and yet often overlooked challenge in cell replacement therapies for the central nervous system is the limited initial survival of transplanted cells; it has been estimated that less than 10% of the transplanted progenitors survive and form the graft. This limited initial survival contributes to variability of therapeutic outcomes, complicates dosing strategies in clinical trials, and necessitates the production of significantly larger quantities of cell product to achieve the desired therapeutic effect. Therefore, understanding which progenitor cells survive and mature into functional grafts is critical to advancing translational cell replacement therapies and will enable us to define the factors that influence the survival of transplanted progenitor cells. To address this, we have developed a molecular barcoding strategy to track the clonal expansion and survival of transplanted mesencephalic dopaminergic (mesDA) progenitor cells. These molecular barcodes are expressed after genomical integration by viral transduction into human embryonic stem cell-derived mesDA progenitor cells and subsequently transplanted into 6-hydroxydopamine (6-OHDA)-lesioned nude rats, an established preclinical model for PD. Graft survival and cellular composition were assessed by immunohistochemistry and single-nucleus RNA sequencing at early time points after transplantation. These analyses of these barcoded mesDA progenitors enabled assessing the evolving composition of the graft at early time points after transplantation and tracking the clonal expansion and modelling of surviving progenitors. The data from this study improves our understanding of cell survival and graft diversification after transplantation. It will enable the development of strategies to obtain more consistent graft composition and to increase initial cell viability. Ultimately, these advances could improve clinical trial outcomes by reducing variability and minimizing the required cell dose, bringing us closer to more reliable and effective cell replacement therapies for PD.
