Application of adipose tissue-derived stem cell therapy with a clinically relevant dose does not significantly affect atherosclerotic plaque characteristics in a streptozotocin-induced hyperglycaemia mouse model

Aims: Diabetes mellitus (DM) induces increased inflammation of atherosclerotic plaques, resulting in elevated plaque instability. Mesenchymal stem cell (MSC) therapy was shown to decrease plaque size and increase stability in non-DM animal models. We now studied the effect of MSC therapy in a streptozotocin-induced hyperglycaemia mouse model using a clinically relevant dose of adipose tissue-derived MSCs (ASCs). Methods: Hyperglycaemia was induced in male C57BL/6 ApoE−/− mice (n=24) via intraperitoneal streptozotocin (STZ) injection (0.05 mg/g bodyweight) for 5 consecutive days. 16 weeks after the first STZ injection, the mice received either 100,000 ASCs (n=9) or vehicle (n=14) intravenously. The effects of ASC treatment on the size and stability of aortic root atherosclerotic plaques were determined 4 weeks post-treatment via (immuno)histochemical analyses. Furthermore, plasma monocyte subsets within 3 days pre- and 3 days post-treatment, and 4 weeks post-treatment, were studied. Results: ASC treatment did not significantly affect atherosclerotic plaque size or intra-plaque inflammation. Although ASC-treated mice had a higher percentage of intra-plaque fibrosis (42.5±3.3%) compared to vehicle-treated mice (37.6±6.8%, p=0.07), this did not reach significance. Additionally, although differences in the percentages of circulating pro- and anti-inflammatory monocytes were observed after ASC treatment compared to pre-treatment (p=0.005), their levels did not differ significantly at any time point compared to vehicle-treated mice. Conclusions: ASC treatment with a clinically relevant dose did not significantly affect atherosclerotic plaque size or intra-plaque inflammation in a hyperglycaemia mouse model. Despite a borderline significant improvement in intraplaque fibrotic content, the potential of ASC treatment on atherosclerotic plaque stability in a diabetic environment remains to be determined.