BACKGROUND: 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 Alzheimers 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).
METHODS: 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.
RESULTS: iPericytes were morphologically similar to HBVPs and expressed canonical pericyte markers. However, iPericytes had 1864 differentially expressed genes compared to HBVPs, while there were 797 genes differentially expressed between neural crest and mesoderm iPericytes. Consistent with the ability of HBVPs to respond to PDGF-BB signalling, PDGF-BB enhanced and a PDGF receptor-beta inhibitor 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 PDGFR beta inhibition, but responded most robustly to vasoconstrictive mediators.
CONCLUSIONS: iPericytes express pericyte-associated genes and proteins and, exhibit an appropriate physiological response upon exposure to a key endogenous mitogen or vasoactive mediators. Therefore, the generation of functional iPericytes would be suitable for use in future investigations exploring pericyte function or dysfunction in neurological diseases.

Single-molecule experiments allow understanding of the diversity, stochasticity, and heterogeneity of molecular behaviors and properties hidden by conventional ensemble-averaged measurements. They hence have great importance and significant impacts in a wide range of fields. Despite significant advances in single-molecule experiments at ultralow concentrations, the capture of single molecules in solution at normal concentrations within natural biomolecular processes remains a formidable challenge. Here, a high-density, well-defined nanofluidic aptamer nanoarray (NANa) formed via site-specific self-assembly of well-designed aptamer molecules in nanochannels with nano-in-nano gold nanopatterns is presented. The nanofluidic aptamer nanoarray exhibits a high capability to specifically capture target proteins (e.g., platelet-derived growth factor BB; PDGF-BB) to form uniform protein nanoarrays under optimized nanofluidic conditions. Owing to these fundamental features, the nanofluidic aptamer nanoarray enables the stochastic capture of single PDGF-BB molecules at a normal concentration from a sample with an ultrasmall volume equivalent to a single cell by following Poisson statistics, forming a readily addressable single-protein nanoarray. This approach offers a methodology and device to surpass both the concentration and volume limits of single-protein capture in most conventional methodologies of single-molecule experiments, thus opening an avenue to explore the behavior of individual biomolecules in a manner close to their natural forms, which remains largely unexplored to date.