The ultrastructural characterization and immunophenotypic features of telocytes in the myocardium and aortic bulb of young and adult Tibetan sheep.

Telocytes (TCs) are stromal cells characterized by unique long protrusions, known as telopodes (TPs), that establish extensive cellular networks within tissues. They are involved in various functions, including tissue metabolism, mechanical support, and immune regulation. This study aims to investigate the distribution patterns and potential functions of TCs in the myocardium and aortic bulb of young and adult Tibetan sheep by using transmission electron microscopy (TEM), immunohistochemistry, immunofluorescence, and Western blotting techniques. The results demonstrate the existence of TCs in Tibetan sheep hearts and the morphological features changed with age. Compared with the young Tibetan sheep, the TPs were longer and more extensively branched with developed protrusions both in the myocardium and aortic bulb of adult. Immunohistochemical and immunofluorescence staining confirmed that the phenotypic expression of TC markers such as CD34, CD117, α-SMA, and PDGFR-α. Moreover, protein expression analysis revealed that there was no significant differences in CD117 and CD34 between young and adult Tibetan sheep, while α-SMA and PDGFR-α expression was significantly higher in the myocardium of young sheep compared to the adults (P < 0.001), but there was no significant difference in the aortic bulb. This study reveals that there are changes in the ultrastructural characterization and immunophenotypic features of TCs in the myocardium and aortic bulb of Tibetan sheep with age, suggesting that TCs play an important role in cardiac development, angiogenesis and functional stability. Therefore, the findings provides clues for further research on characteristics of TCs in plateau hypoxia environment and their potential role in cardiac development.