Abstract Body (Do not enter title and authors here): BACKGROUND: To apply human pluripotent stem cell-derived endothelial cells (hPSC-ECs) in regenerative medicine, exploring methods for highly purified ECs is desirable. Cell sorting is a versatile technique for isolating and purifying specific cell types, yet mechanical cell loss persists. Previously, we established a differentiation method for human induced pluripotent stem cell-derived ECs (hiPSC-ECs) based on lineage control using vascular endothelial growth factor (VEGF) and 8-Bromo cyclic adenosine monophosphate (cAMP). However, achieving high hiPSC-ECs purity without cell sorting has not yet been possible.
HYPOTHESIS: We speculated that applying digital rocker-generated shear stress during a specific period of hiPSC-EC induction would yield highly purified hiPSC-ECs without cell sorting.
METHODS: We applied cyclic share stress to the cultured cells using a digital rocker. To optimize the frequency and duration of digital rocker application, ECs purity on day 13 of differentiation (d13) was analyzed by flow cytometry for vascular endothelial cadherin (VE-Cadherin). Shear stress was measured using a simulation model. The functionality of ECs was evaluated through reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) for endothelial nitric oxide synthase (eNOS) and angiogenesis assay.
RESULTS: The optimized protocol consisted of a rocking period from day 5 (representing the EC progenitor stage) to d13, at 30 cycles/min with 13° tilt (equivalent to 1.09 dyn/cm²), which significantly increased the purity of ECs (Control vs Rocking: VE-Cadherin; 69.25±17.43 vs 86.68±6.023 %, P = 0.0090). Examining the number of cells on d13 revealed rocking stimulation reduced both ECs and non-ECs. Non-ECs were nearly absent, suggesting EC purification occurs by removing non-ECs, indicating ECs are more resistant to being eliminated by the rocking stimulation. The rocking culture also led to increased eNOS mRNA expression on d13 (Control vs Rocking: 0.5574±0.4985 vs 1.056±0.1652, P = 0.0393). The angiogenesis assay showed a longer vascular structure length trend in the rocking group, indicating enhanced angiogenic capacity. (Control vs Rocking: 15407±2929 vs 18335±3568 Pixel, P= 0.4309).
CONCLUSION: In this study, we developed a method where digital rocker-generated shear stress during a specific period of hiPSC-EC induction not only selectively purifies ECs without cell sorting, but also enhances endothelial function, demonstrating their therapeutic potential.