Fig. 5: An anti-L1CAM antibody (Ab417) mitigates irradiation (IR)- and Dox-induced cardiotoxicity and increases survival.

a, b Co-culture of iPSC-CMs and irradiated ECs transfected with control or L1CAM siRNA. a Schematic of the procedure for co-culture of iPSC-CMs and irradiated ECs. ECs were transfected with control or L1CAM-specific siRNA and irradiated with 10 Gy. Forty-eight hours after IR, the ECs were co-cultured with iPSC-CMs (top). The beating rates of the iPSC-CMs were examined after 5 days of co-culture with irradiated ECs (bottom). Error bars represent mean ± SD (No IR vs. si-Control+IR p = 0.0005; si-Control+IR vs. si-L1CAM + IR p > 0.0001). b Immunofluorescence staining (left panel) and quantification (right panel) of cTnT expression in cardiomyocytes and the collagen I deposition area in co-cultured cells (magnification, ×200). Scale bar = 50 μm. Error bars represent mean ± SD (cTnT expression: No IR vs. si-Control+IR p = 0.0239; si-Control+IR vs. si-L1CAM + IR p = 0.0475, collagen I deposition: No IR vs. si-Control + IR p = 0.027; si-Control + IR vs. si-L1CAM + IR p = 0492). c–e Mice were injected intravenously with control IgG or Ab417 (10 mg/kg) three times a week for 2 weeks and received 16 Gy thoracic IR. f–h Mice were injected intravenously with control IgG or Ab417 (10 mg/kg) with or without intraperitoneal Dox injection (4 mg/kg) three times a week for 2 weeks. c, f Cumulative survival analysis measured in days after treatment (n = 8 animals per group). d, g Echocardiography results (upper panels) and quantification (lower panels) of FS (%), LVEF (%), LVESV (μL), and LVEDV (μL) (No IR n = 10; IR + IgG n = 5, IR + Ab417 n = 5; No Dox n = 10; Dox+IgG n = 5, Dox + Ab417 n = 5). Scale bar = 1 mm. Error bars represent mean ± SD (FS: No IR vs. IR + IgG p = 0.0331; IR + IgG vs. IR + Ab417 p = 0.0172; Dox+IgG vs. Dox + Ab417 p = 0.0046, LVEF: No IR vs. IR + IgG p = 0.0284; IR + IgG vs. IR + Ab417 p = 0.0182; Dox + IgG vs. Dox + Ab417 p = 0.0027, LVEDV: No IR vs. IR + IgG p = 0.0099; IR + IgG vs. IR + Ab417 p = 0.0054; No Dox vs. Dox p = 0.0003; Dox + IgG vs. Dox + Ab417 p = 0.003, LVESV: No IR vs. IR + IgG p = 0.0005; IR + IgG vs. IR + Ab417 p = 0.0002, ****p < 0.0001). e, h Haematoxylin and eosin–stained ventricular myocardium (upper panels) and quantification (lower panels) of cardiomyocyte cross-sectional area (No IR n = 7; IR + IgG n = 8; IR + Ab417 n = 8; No Dox n = 7; Dox + IgG n = 8; Dox+Ab417 n = 8) (magnification, ×400). Scale bar = 20 μm. Error bars represent mean ± SEM (No IR vs. IR + IgG p = 0.0003; IR + IgG vs. IR + Ab417 p = 0.0002; No Dox vs. Dos+IgG p = 0.024; Dox + IgG vs. Dox + Ab417 p = 0.0493). (a, d: log-rank Mantel-Cox test; all other panels: one-way ANOVA for multiple comparisons).