![SARS-CoV-2 infection in the K18-hACE2 mouse model. (A) Schematic representation of the mouse experimental protocol. K18-hACE2 mice were inoculated intranasally with SARS-CoV-2 (250 TCID50) or control media. Tissues (plasma [blood], bone marrow, and lung) were collected at 3 and 7 days after infection (DPI). (B) Survival curve of K18-hACE2 mice upon challenge with SARS-CoV-2 (250 TCID50, red color) or with control media (Mock, black color). Mortality (end point requiring euthanasia) expressed as percentage of survival was monitored every day for 10 days (top; n = 17-19 per group). Survival curve statistical analysis was calculated with Log-rank (Mantel-Cox) test; ∗∗∗∗P < .0001. Weight change (bottom; n = 4-40) was also reported every day for 10 days and expressed as mean (± SD) percentage of weight at day 0; the average weight before infection was 19.55 ± 2.95 g. Unpaired t-test with Welch correction was used to determine significance (∗P < .05; ∗∗P < .01; and ∗∗∗P < .001). (C) Lung sections were stained with a Modified Carstairs method for fibrin and platelets detection: fibrin (bright red), platelets (gray-blue), collagen (bright blue), and red blood cells (orange-yellow). Platelet thrombus (arrow head) and cell infiltration (asterix) are indicated (scale bar, 100 μm). (D) Lung damage was evaluated using a histological score (left) and lung virus titer (right) was quantified at 3 and 7 DPI using lung homogenate on vero cells and expressed in TCID50 per mg of tissue (n = 4-5 per group). Statistics: Mann-Whitney test; ∗P < .05. (E) Heat map of cytokine and growth factor profiles in blood plasma (blood), bone marrow plasma (bone marrow), and lung during SARS-CoV2 infection (3 DPI, 7 DPI, or Mock). Cytokine levels (pg/mL) were subdivided into 3 groups: 0 to 80 pg/mL (low), 0 to 450 pg/mL (mid), and 0 to 75 000 pg/mL (high). The mean concentration for each cytokine is indicated (n = 4-5). Statistics: 1-way analysis of variance (ANOVA) with Dunnett multiple comparisons (compared with Mock); ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; and ∗∗∗∗P < .0001; n = 4-5 per group.](https://ash.silverchair-cdn.com/ash/content_public/journal/bloodadvances/8/11/10.1182_bloodadvances.2023012367/2/blooda_adv-2023-012367-gr1.jpeg?Expires=1726828048&Signature=WYQzM-zZ-30O~vj8YY5lva1dyT512dlN7ZKVE7pJO3K5-Vo3NTQuZtMh0RqNPTVSMMuI28INap9WfSffNmiUBgfCvSXgDj2hpXOjbIAg0Dt1S3JNdXOURDswdHYh2nqpWcT6uWhZUvva6qL584chUO3L7q1jLS3LWNmpiaJXSdfUj55qhTigzkmDviLGGjKJCXfCRFBokKxGhyQUzJtP0BidEH4CBFj7u3Cq-Wrm-X57HUuPPcAZMXuOQt685Q9oB1wBGCoCmXbJv~60ZrhsIaTwTDTj~l-KvrJj3UPtCa3t-kqkc-yni533cl66V2P2liYGzsbIdLq5Jk3Rl-3L9w__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
SARS-CoV-2 infection in the K18-hACE2 mouse model. (A) Schematic representation of the mouse experimental protocol. K18-hACE2 mice were inoculated intranasally with SARS-CoV-2 (250 TCID50) or control media. Tissues (plasma [blood], bone marrow, and lung) were collected at 3 and 7 days after infection (DPI). (B) Survival curve of K18-hACE2 mice upon challenge with SARS-CoV-2 (250 TCID50, red color) or with control media (Mock, black color). Mortality (end point requiring euthanasia) expressed as percentage of survival was monitored every day for 10 days (top; n = 17-19 per group). Survival curve statistical analysis was calculated with Log-rank (Mantel-Cox) test; ∗∗∗∗P < .0001. Weight change (bottom; n = 4-40) was also reported every day for 10 days and expressed as mean (± SD) percentage of weight at day 0; the average weight before infection was 19.55 ± 2.95 g. Unpaired t-test with Welch correction was used to determine significance (∗P < .05; ∗∗P < .01; and ∗∗∗P < .001). (C) Lung sections were stained with a Modified Carstairs method for fibrin and platelets detection: fibrin (bright red), platelets (gray-blue), collagen (bright blue), and red blood cells (orange-yellow). Platelet thrombus (arrow head) and cell infiltration (asterix) are indicated (scale bar, 100 μm). (D) Lung damage was evaluated using a histological score (left) and lung virus titer (right) was quantified at 3 and 7 DPI using lung homogenate on vero cells and expressed in TCID50 per mg of tissue (n = 4-5 per group). Statistics: Mann-Whitney test; ∗P < .05. (E) Heat map of cytokine and growth factor profiles in blood plasma (blood), bone marrow plasma (bone marrow), and lung during SARS-CoV2 infection (3 DPI, 7 DPI, or Mock). Cytokine levels (pg/mL) were subdivided into 3 groups: 0 to 80 pg/mL (low), 0 to 450 pg/mL (mid), and 0 to 75 000 pg/mL (high). The mean concentration for each cytokine is indicated (n = 4-5). Statistics: 1-way analysis of variance (ANOVA) with Dunnett multiple comparisons (compared with Mock); ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; and ∗∗∗∗P < .0001; n = 4-5 per group.
