Periodic Reporting for period 1 - ReplaceMi (Microglia engineering and replacement to treat brain disease)
Periodo di rendicontazione: 2023-08-01 al 2026-01-31
Microglia are brain-resident immune cells that play central roles in maintaining healthy brain physiology. Microglial dysfunction is an important driver of many neurological disorders, making them a promising target for therapeutic intervention. Unlike most immune cells, microglia originate during early development and sustain themselves throughout life without being replaced by bone marrow progenitors. This remarkable self-renewal capacity makes them attractive for cell therapy. Replacing dysfunctional microglia with healthy or engineered counterparts that subsequently self-maintain could offer entirely new ways to treat brain disease. This project aims to establish the foundations for microglia engineering and replacement therapy, by (1) developing strategies to replace microglia, (2) generating stem cell-derived progenitors that can engraft as bona fide microglia, (3) creating platforms to functionally probe and tailor these cells and (4) providing the proof-of-concept that direct microglia replacement can provide lasting therapeutic benefit in the context of neurodegenerative diseases.
We are actively developing approaches for efficient replacement of endogenous microglia with transplanted progenitors. Our work has shown that even blood-derived progenitors can enter the brain and replace microglia, if host microglia are depleted and prevented from repopulating for an extended period. We are now developing translatable strategies to enhance this process by giving transplanted cells a competitive advantage.
A second objective has been to identify progenitors that efficiently engraft the brain and develop into bona fide microglia. We demonstrated that in contrast to adult bone marrow-derived progenitors, fetal monocytes have the intrinsic potential to develop into microglia that closely resemble their endogenous counterparts. Building on this, we generated induced pluripotent stem cell (iPSC)-derived progenitors that efficiently engraft the brain and closely resemble native microglia. These cells adopt normal microglial morphology and gene expression, can be genetically engineered, and show self-renewal. We are currently testing their therapeutic potential in neurodegenerative disease models, and have created engineered lines that overexpress therapeutically relevant proteins. Finally, we have developed a novel platform that combines microglia replacement with advanced genetic screening directly in the brain. This approach enables screening of gene function in microglia within their native environment, providing a powerful way to uncover the gene networks that regulate their survival, renewal, and activation. Together, these advances establish new methodologies for studying microglia in health and disease and lay the foundation for future microglia-based therapies.
A second objective has been to identify progenitors that efficiently engraft the brain and develop into bona fide microglia. We demonstrated that in contrast to adult bone marrow-derived progenitors, fetal monocytes have the intrinsic potential to develop into microglia that closely resemble their endogenous counterparts. Building on this, we generated induced pluripotent stem cell (iPSC)-derived progenitors that efficiently engraft the brain and closely resemble native microglia. These cells adopt normal microglial morphology and gene expression, can be genetically engineered, and show self-renewal. We are currently testing their therapeutic potential in neurodegenerative disease models, and have created engineered lines that overexpress therapeutically relevant proteins. Finally, we have developed a novel platform that combines microglia replacement with advanced genetic screening directly in the brain. This approach enables screening of gene function in microglia within their native environment, providing a powerful way to uncover the gene networks that regulate their survival, renewal, and activation. Together, these advances establish new methodologies for studying microglia in health and disease and lay the foundation for future microglia-based therapies.
We have developed mouse iPSC-derived progenitors that have the potential to adopt the identity of microglia, coupled to transplantation strategies that allow for their use in the replacement of endogenous microglia. This provides a versatile way to replace host microglia with engineered counterparts, opening the door to both fundamental studies and therapeutic applications. Building on this, we established a novel in vivo screening pipeline that integrates microglia replacement with high-throughput genetic perturbation. This strategy makes it possible to test the function of many genes directly in microglia within their native brain environment. By linking gene perturbations with transcriptional and functional readouts, this platform enables systematic mapping of the genes and gene-regulatory networks that shape microglial identity and function.