Bariatric arterial embolization: Effect of microsphere size on the suppression of fundal ghrelin expression and weight change in a swine model

Purpose: To determine whether microsphere size effects ghrelin expression and weight gain after selective bariatric arterial embolization (BAE) in swine. Materials and Methods: BAE was performed in 10 swine by using smaller (100-300 mm; n = 5) or larger (300-500 mm; n = 5) calibrated microspheres into gastric arteries. Nine control pigs underwent a sham procedure. Weight and fasting plasma ghrelin levels were measured at baseline and weekly for 16 weeks. Ghrelin-expressing cells (GECs) in the stomach were assessed by using immunohistochemical staining and analyzed by using the Wilcoxon rank-sum test. Results: In pigs treated with smaller microspheres, mean weight gain at 16 weeks (106.9% ± 15.0) was less than in control pigs (131.9% ± 11.6) (P < .001). Mean GEC density was lower in the gastric fundus (14.8 ± 6.3 vs 25.0 ± 6.9, P < .001) and body (27.5 ± 12.3 vs 37.9 ± 11.8, P = .004) but was not significantly different in the gastric antrum (28.2 ± 16.3 vs 24.3 ± 11.6, P = .84) and duodenum (9.2 ± 3.8 vs 8.7 ± 2.9, P = .66) versus in control pigs. BAE with larger microspheres failed to suppress weight gain or GECs in any stomach part compared with results in control swine. Plasma ghrelin levels were similar between BAE pigs and control pigs, regardless of microsphere size. Week 1 endoscopic evaluation for gastric ulcers revealed none in control pigs, five ulcers in five pigs embolized by using smaller microspheres, and three ulcers in five pigs embolized by using larger microspheres. Conclusion: In bariatric arterial embolization, smaller microspheres rather than larger microspheres showed greater weight gain suppression and fundal ghrelin expression with more gastric ulceration in a swine model.