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. 2022 Jan 20;13:405. doi: 10.1038/s41467-021-27893-2

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© The Author(s) 2022

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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Fig. 2 — a Schematic depiction of the cell-based neutralization assay. b Representative flow profiles showing the percentage (fluorescence mean intensity) of RBD-AF647 binding (at 16 and 3.3 nmol/L) to ACE2⁺ HEK-293 cells, inhibited by rhACE2 and ACE2⁺ EVs (evACE2) isolated from HEK-293 and HeLa cells (HEK-EV1 and HeLa-EV2, respectively) whereas ACE2⁻ EVs (evCon) had no neutralization effects (no RBD in black, PBS in dark blue, rhACE2 in orange, evCon in light blue, and evACE2 in green). c IC₅₀ of rhACE2 (orange line) and ACE2 in the EVs from ACE2⁺ HEK (ev1ACE2) and HeLa (ev2ACE2) cells (green lines) on 16 nM RBD-host cell binding (%). GraphPad Prism 9.0.2 was used to calculate the IC₅₀. N = 2 experiments with two technical replicates for each. Data are presented as mean values ± SD. d IC₅₀ of evACE2, ev1 from HEK and ev2 from HeLa cells (green lines), and rhACE2 (orange line) neutralizing infections by wild-type (WT) S⁺ pseudotyped SARS-CoV-2. GraphPad Prism 9.0.2 was used to calculate the IC₅₀. N = 2 experiments with two technical replicates for each. Data are presented as mean values ± SD. e IC₅₀ (nM) of ACE2 in ev1ACE2 (HEK) (green line) and rhACE2 (orange line) upon wild-type SARS-CoV-2 infection. GraphPad Prism 9.0.2 was used to calculate the IC₅₀ with three biological replicates. Data are presented as mean values ± SD. f Distinct effects of ACE2⁺ EVs (green lines) and ACE2⁻ control EVs (light blue line) on inhibiting Vero-6 cell death caused by SARS-CoV-2. N = 2 experiments with three biological replicates each. Data are presented as mean values ± SD. g The IC₅₀ of ev1ACE2 (HEK) neutralizing infections by pseudotyped SARS-CoV-2 expressing WT (black), B.1.1.7 (α) variant (red), B1.351 (β) variant (dark blue) and B.1.617.2 (δ) (light green) S protein. GraphPad Prism 9.0.2 was used to calculate the IC₅₀. N = 2 experiments with two technical replicates each. Data are presented as mean values ± SD. h Effects of ev1ACE2 (HEK) on protecting Vero-6 cell viability against infections of SARS-CoV-2 WT (black), B.1.1.7 (α) variant (red) and B1.351 (β) variant (dark blue) (n = 3 biological replicates). Data are presented as mean values ± SD.