To date, many diseases have been studied using a single disease-relevant cell type derived from iPSCs. For example, iPSC-derived neurons have been used to model Alzheimer’s disease54,56–68 (Table 2) and Parkinson’s disease (Table 3)43–45,55,69–84. However, more than one cell type may be required to effectively model some diseases. Indeed, comparable efforts have been devoted to model schizophrenia using patient iPSC-derived neurons85–87 and neural progenitor cells88–92. To better recapitulate disease phenotypes, co-culture of more than one cell types may also be needed to study the interaction of different cell types. For example, astrocyte/neuron co-cultures have been used to model the pathology of amyotrophic lateral sclerosis (ALS)93–96. The co-culture system allowed the investigation of non-cell-autonomous aspects of disease pathology, which would otherwise be impossible with single cell types, such as neurons. Moreover, these studies enabled the identification of astrocytes as a critical cellular component contributing to motor neuron degeneration in ALS and provided a drug screening platform for ALS using patient iPSC-derived astrocytes93–96.
