The human brain is a complex organ that presents many challenges for neuroscientists. For instance, tissue availability represents a major problem given that this organ does not regenerates, making it next to impossible to obtain live tissue from patients that would allow to study how cells in the brain change and interact with each other in the contexts of aging and brain diseases. To obtain brain cells in a dish, we and others have developed ways to convert skin cells to neurons, the main functional component of the brain. However, the brain is composed of multiple other cell types, also very important to proper brain function, including immune cells such as microglia. Microglia are essential in protecting the brain against pathogens, but are also thought to contribute to the development of neurodegenerative disorders associated with aging, such as Parkinson’s and Alzheimer’s disease. This projects aims to convert skin cells obtained from senior donors to microglia, and study the aging signature in these cells. The completion of this project will not only provide a new tool to gain insight into the role of microglia in the contexts of aging and brain diseases, but also allow the development of sophisticated human brain tissues derived from the skin of patients with brain diseases, to study interaction between different cell types of the brain and test new therapies.