It's all about the feeding: A High-throughput analysis of Hes-7 dynamics in hiPSC-derived Somitoids

During somitogenesis, the presomitic mesoderm segments sequentially to form somites, which are the precursors of the bones, muscles, and part of the dermis. The segmentation clock is a molecular oscillator that regulates and coordinates the spatiotemporal timing of somite formation. Characterisation of human presomitic mesoderm has been enabled by the recent advances in the culture of human induced pluripotent stem cells and organoids. 

However, organoids that recapitulate somitogenesis have not been categorised at scale, and it has not been shown that they can be staged across the segmentation clock cycle. Here, a high-throughput system was developed which addresses these issues.  Human-induced pluripotent stem cell-derived somitoids (in vitro organoid model recapitulating the segmentation clock) were cultured in a 384-well plate, and a programmable feeding schedule was used to stagger the initiation of oscillations. An automated, custom pipeline for image processing, segmentation, and analysis was developed that can represent Hes7-Achilles oscillations using a small number of parameters.  

The results showed that by staging feeding gates, the Hes7-Achilles signal could be distributed across the segmentation clock cycle, a finding corroborated by follow-up qPCR. In addition, media change on an existing oscillation induces a Type 0 phase response, in which the segmentation clock is reset to a high-Wnt/low-Notch transcriptional state. Perturbing the plate causes a Type 2 phase response in which the segmentation clock can be accelerated or delayed.  

Venue: Fulton G20