Using Oligodendrocytes for studies in Alzheimer disease

Abstract Background Genomic regulatory architecture (GRA) has been primarily studied in European ancestry. As part of the functional Consortium of the Alzheimer Disease Sequencing Project, we are determining the GRA in African and Amerindian ancestries. Oligodendrocytes (OLs) are the largest glial population in the adult central nervous system. While their main role is to support neuronal metabolism and connectivity, few studies have examined their importance in Alzheimer’s disease (AD), despite reports of low numbers of oligodendrocytes and reduced myelin in the early stages of AD and a demonstrated role of myelinating oligodendrocytes in learning and memory. Several studies have reported the derivation of OLs from pluripotent cells, such as induced pluripotent stem cells (iPSC) to be challenging. Here, we optimized a protocol to derive oligodendrocytes from iPSC for studies in AD patients with different ancestries and how ancestry‐specific genomic differences drive the onset and pathogenesis of AD. Method iPSC lines derived from AD patients were cultured and differentiated into oligodendrocytes using different induction media, as well as different seeding densities. The cells in each treatment were compared at multiple time points using immunocytochemistry (ICC) and qRT‐PCR for oligodendroglia lineage markers with the goal of identifying the culture conditions that increase the yield of O4 + cells and myelinating oligodendrocytes. Result Our results showed that increasing the initial seeding density positively correlates with the number of Olig2 + cells that subsequently transitioned into mature O4+ cells capable of producing myelin. Additionally, we showed that the addition of N2 supplement to the induction media was necessary to maintain the cell viability during the initial stage of differentiation. Conclusion We have optimized a protocol to derive OLs from human iPSC lines. We determined that both the seeding density and the media supplements used during the initial stage of differentiation directly influence viability and, consequently the amount Olig2 + cells that could be obtained to be terminally differentiated into O4 + and myelinating cells. Our optimized protocol will be used to evaluate the GRA and functionality of potential GWAS driving loci in cultured oligodendrocytes from individuals of African and Amerindian ancestries.