iPSCs are adult cells (like skin cells) that have been reprogrammed back to an embryonic-like state. They can become any cell type in the body. It's like hitting the "reset button" on a fully grown cell, turning it back into a blank canvas that can then be directed to become brain cells, heart cells, or in this case, microglia (brain immune cells).
Why they matter for MCHS: Patient-derived iPSCs allow researchers to take skin cells from someone with MCHS, turn them into brain cells in a lab dish, and study what's going wrong. This gives a "living model" of MCHS that's much more informative than just looking at gene sequences. The Volare Study has delivered the first patient-derived iPSC lines, which means researchers can now grow MCHS patient brain cells for testing.