Flow-enhanced vascularization and maturation of kidney organoids in vitro

Source

PDF: raw/sources/homan_2019_flow-enhanced_vascularization_and_maturation.pdf
Article: Nature Methods
Labs: Jennifer A. Lewis (Harvard Wyss Institute) + Ryuji Morizane (Brigham and Women's / Harvard Medical)
Status: deep ingested 2026-04-09

Starting material: hPSC-derived kidney organoids following Morizane 2016 / Takasato 2016-type differentiation
Device: 3D-printed millifluidic chip with gelatin-fibrin ("gelbrin") ECM coating
Fluidic shear stress (FSS) tested: low (0.0001 dyn/cm²) to high (0.008-0.035 dyn/cm²)
Media optimization: low FBS (1.5%) permits both nephrogenesis and vascular network formation
Timepoints: days 12-35 of differentiation with 10 days perfusion
Readouts: PECAM1/MCAM immunostaining, AngioTool vessel quantification, podocyte markers, nephron maturation scRNA-seq, VEGF gradient disruption experiments

5× increase in PECAM1+ vessel area under high FSS vs. low FSS.
Developing kidney organoids exposed to flow show:
Expanded endogenous endothelial progenitor pool
Perfusable vascular networks with luminal architecture surrounded by mural cells
Enhanced cellular polarity in podocytes and tubular compartments
More mature adult gene expression in both vascular and tubular cells
Glomerular vascular development progresses through intermediate stages resembling embryonic capillary loop formation abutting foot processes.
VEGF gradient disruption reduces vessel-nephron association — confirming endogenous signaling axis.
Gelbrin ECM (vs. glass, plastic, fibrin alone) critical for peripheral PECAM1 expression.

First organ-on-chip / microfluidic paper in the collection — fills a major gap.
Solves a specific, well-known problem: static kidney organoids are avascular and immature.
Alternative to in vivo transplantation for kidney organoid vascularization.
Bridges the "static culture" bulk of the kidney organoid literature (Xia, Takasato, Morizane, Vanslambrouck) with organ-on-chip maturation.

Requires custom 3D-printed millifluidic device — not all labs can adopt.
Vessel maturation is improved but still not equivalent to adult kidney.
10-day perfusion is short relative to the months-long kidney organoid differentiation.
"Flow over top" is not physiological perfusion through lumens.

Direct extension of Morizane 2016 / Takasato 2016 kidney organoid work.
Pairs with Wimmer 2019 (stand-alone vessels), Cakir 2019 (brain vascularization), Wörsdorfer 2019 (MPC mixing) to form the organoid vascularization cluster.
First concrete demonstration that mechanical (flow) stimulation can substitute for in vivo niche in organoid maturation.

Does flow-enhanced maturation transfer to other organoid systems (lung, intestine)?
What is the maximum maturation achievable with longer perfusion (weeks-months)?
How does flow-driven vs. TF-driven (Cakir) vs. cell-mixing (Wörsdorfer) vascularization compare on fidelity and throughput?

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