Induced pluripotent stem cell derived pericytes respond to endogenous mediators of proliferation and contractility
Pericytes are multifunctional contractile cells that reside on capillaries. Pericytes are critical regulators of cerebral blood flow and blood-brain barrier function, and pericyte dysfunction may contribute to the pathophysiology of human neurological diseases including Alzheimer's disease, multiple sclerosis, and stroke. Induced pluripotent stem cell (iPSC)-derived pericytes (iPericytes) are a promising tool for vascular research. However, it is unclear how iPericytes functionally compare to primary human brain vascular pericytes (HBVPs). We differentiated iPSCs into iPericytes of either the mesoderm or neural crest lineage using established protocols. We compared iPericyte and HBVP morphologies, quantified gene expression by qPCR and bulk RNA sequencing, and visualised pericyte protein markers by immunocytochemistry. To determine whether the gene expression of neural crest iPericytes, mesoderm iPericytes or HBVPs correlated with their functional characteristics in vitro, we quantified EdU incorporation following exposure to the key pericyte mitogen, platelet derived growth factor (PDGF)-BB and, contraction and relaxation in response to the vasoconstrictor endothelin-1 or vasodilator adenosine, respectively. iPericytes were morphologically similar to HBVPs and expressed canonical pericyte markers. Consistent with the ability of HBVPs to respond to PDGF-BB signalling, PDGF-BB enhanced and PDGF receptor (PDGFR)ß inhibitors impaired iPericyte proliferation. Administration of endothelin-1 led to iPericyte contraction and adenosine led to iPericyte relaxation, of a magnitude similar to the response evoked in HBVPs. We determined that neural crest iPericytes were less susceptible to PDGFRß inhibition, but responded most robustly to vasoactive meditators.  iPericytes express pericyte-associated genes and proteins and, exhibit an appropriate physiological response upon exposure to a key endogenous mitogen or vasoactive mediators. Therefore, this protocol to generate functional iPericytes would be suitable for use in future investigations exploring pericyte function or dysfunction in neurological diseases. Overall design: To investigate the suitability of iPSC-derived pericytes for investigations into neurological diseases we differentiated iPSCs into iPericytes via either mesoderm or neural crest lineage and compared these to each other and to primary human brain vascular pericytes.