Functional validation of angiogenesis. A, Experimental schema of rat aortic ring angiogenesis assay adapted for screening serum. B, Capillary sprouting in rat aorta challenged with serum from PBS or manual metal arc welding using stainless steel electrodes (MMA-SS) exposed animals. C, Quantification of vascular outgrowth indicates serum from MMA-SS exposed rats caused enhanced angiogenesis in naïve aortic rings. The graph was presented as mean ± SE. Each point in the graph was an average of 3 technical replicates of individual measurement from the treatment groups (n = 4, Control; 6, gas metal arc welding using mild steel electrodes [GMA-MS]; 5, MMA-SS; and 3, Control + VEGF). One-way ANOVA with Tukey’s multiple comparison post hoc test was performed and * denotes statistical significance from control. $denotes statistical significance from GMA-MS. & denotes statistical significance from MMA-SS. A p < .05 was considered statistically significant.