Abstract Body (Do not enter title and authors here): Diabetes mellitus exacerbates myocardial ischemia/reperfusion injury (MI/R) by incompletely understood mechanisms. We previously reported that dysfunctional adipocyte-derived small extracellular vesicles (sEV) enhancing cardiac injury. However, the mechanism of selectively increased uptake of the adipocyte-derived sEV by cardiomyocytes remains to be further interrogated. In this study, adult male mice were fed a normal or a high-fat diet for 12 weeks and sEV from epididymal adipocytes were collected. We subjected the sEV to the proteinase K assay and observed that adipocyte-derived sEV membrane surface carries high molecular weight adiponectin, an adipocyte-specific secretory protein, especially in high-fat diet group. We further discovered that knocking down of T-cadherin in cardiomyocytes, a specific binding partner of adiponectin only anchored outside cell membrane, significantly increased the high-fat diet adipocyte-sEV uptake by cardiomyocytes and exacerbated the cardiac injury. In order to testing the hypothesis that T-cadherin is the cardiomyocyte “gatekeeper” for the internalization of High-fat diet sEV by recognizing and catching them, we incubated T-cadherin overexpression cardiomyocytes with pkh67-labeled adipocyte-sEV. Result showed that pkh67 signal mostly located in the cell membrane in T-cadherin overexpression group, as compared to that pkh67 signal mostly detected in the cytoplasm in knock down group. We also found that T-cadherin is colocalized with Caveolin-3, a key component of caveolae for endocytosis, which strongly suggests the underlying mechanisms of the internalized of the sEV by their interaction. Next, we conducted high-fat diet T-cadherin KO mice to verify and found more sever MI/R in KO group than wildtype group, including larger infarct size, higher CK-MB, weaker contraction function and increased cleaved caspase 3. In summary, T-cadherin is responsible for one of the mechanisms for diabetes mellitus exacerbates MI/R. Although the intracellular signaling pathway of T-cadherin need further investigation, our findings still provide insights into adiponectin/T-cadherin-mediated organ protection through sEV delivery and uptake.