Reverse engineering zonation-specific and age-specific iPSC-derived cerebrovascular models based on transcriptomic profiling of the human brain

Project Summary Cerebrovascular dysfunction is emerging as a common pathology in many diseases of the brain, including neurodegenerative diseases, cerebrovascular diseases, as well as in aging. Therefore, understanding the role of cerebrovascular dysfunction in disease progression and aging will be key to long-term maintenance of brain health. With developments in tissue engineering and stem cell technology, in vitro cerebrovascular models can play an important role in understanding the role of cerebrovascular dysfunction in disease progression and aging. Next-generation cerebrovascular models should take into account three key factors: (1) differences in phenotype of brain microvascular endothelial cells along the arterio-venous axis, (intrinsic factors), (2) differences in microenvironmental cues along the arterio-venous axis (extrinsic factors), and (3) changes in zonation-specific cerebrovascular phenotype during aging and in response to aged serum. Therefore, the overall goal of this project is to use zonation- and age-specific intrinsic and extrinsic cues to reverse engineer human cerebrovascular models, and to use these models to understand cerebrovascular phenotype during aging. We will first perform a pooled genetic screen to identify transcription factor combinations that are capable of driving source cells towards gene expression profiles of human brain microvascular endothelial cells along the arterio-venous axis (Aim 1). Three candidate induced brain microvascular endothelial cells (iBMECs) for each zone will be generated using lentiviral transduction. The top candidate for each zone will then be selected from analysis of gene and protein expression profiles (Aim 2). We will then use the three iBMECs to demonstrate zonation-specific cerebrovascular phenotype in zonation-specific models (arteriole, capillary, venule) (Aim 3). Next, we will assess the influence of young and old serum on cerebrovascular phenotype in the zonation-specific models (Aim 4). Finally, we will use the same approach to create an aged cerebrovascular model in one zone. We will create iBMECs that match the transcription factor profile of human brain microvascular endothelial cells in the aged cerebrovasculature, and then assess the role of microenvironmental cues and young/old serum on cerebrovascular phenotype. This project is a collaboration between the Searson group (JHU) with expertise in tissue-engineered microvascular models, and the Heiman group (MIT) with expertise in genomics and molecular mechanisms of neurodegenerative disease. This project builds upon key recent accomplishments from the two labs: (1) the creation of a library of zonation-specific transcription factor profiles for brain microvascular endothelial cells from the human brain, (2) identification of key transcription factors to enable reverse engineering of zonation- specific human brain microvascular endothelial cells, and (3) tissue-engineered platforms for zonation-specific cerebrovascular models.