In‐stent neointimal hyperplasia is less fibrous in metabolic syndrome Ossabaw compared to lean Yucatan swine

Patients with the metabolic syndrome (“pre‐diabetes”) typically have a poorer prognosis after coronary stenting compared to patients with normal glucose metabolism. The mechanisms are unclear, but may be related to more cellular proliferation, inflammation, and less fibrous (less stable) composition of the in‐stent stenosis. Lean Ossabaw swine are predisposed to the metabolic syndrome, as shown by the greater propensity to obesity and insulin‐resistance, compared to lean Yucatan swine; thus, we tested the hypothesis that restenosis of Ossabaw would be less fibrous than Yucatan. Bare metal stents were placed in circumflex arteries with 1:1 apposition (not over‐inflation injury) verified by intravascular ultrasound in male adult Ossabaw (N=7) and Yucatan (N=4) pigs. Percent stenosis and lesion composition were evaluated histologically 3 weeks later using Verhoeff's elastin stain and trichchrome staining for collagen. Percent area of collagen in Yucatan was 34‐fold greater than in Ossabaw coronary artery (6.19±1.59 vs. 0.18±0.06%). This collagen difference is especially striking considering that the percent stenosis of Ossabaw was 2‐fold greater than Yucatan. Conclusion The less fibrous coronary restenosis in the Ossabaw pig suggests a more proliferative and/or lipid‐laden composition, thus potentially more vulnerable restenotic lesions in the Ossabaw model of the metabolic syndrome compared to the lean Yucatan pig. Support: NIH RR13223, HL62552, and Am. Diab. Assoc.