Coelomic fluid of the earthworm Eisenia fetida induces apoptosis of HeLa cells in vitro

Earthworm, Dilong in Chinese, is a traditional Chinese medicine used to treat many diseases including tumors. To investigate whether the coelomic fluid of the earthworm Eisenia fetida inhibits viability and induces apoptosis of HeLa cells, MTT assay, AO/EB fluorescent staining method and DNA agarose electrophoresis were applied. The cytotoxicity of coelomic fluid on HeLa cell showed a concentration dependent manner after 48 h treatment as detected by the MTT assay. Coelomic fluid (1 mg/ml) exhibited toxic effects on HeLa cells with an inhibition rate of 84.22%, leading to cell lysis. The inhibition rates in 0.1 mg/ml and 0.01 mg/ml treatments were 10.24% and 2.99%, respectively. Morphological changes of typical apoptosis were observed by AO/EB staining in 0.1 mg/ml and 0.01 mg/ml concentration with apoptotic rates of 79.1% and 22.2%, while the cells were necrotic in 1 mg/ml concentration as indicated by red stained cells. The agarose gel electrophoresis of DNA revealed a smear pattern at the concentrations of 0.1 mg/ml and 0.01 mg/ml of coelomic fluid. At the concentration of 0.1 mg/ml, the coelomic fluid induced apoptosis in HeLa cells in a time dependent manner. This work suggests that some of the coelomic fluid components might be useful for pharmaceutical applications in the treatment of cancer, but our knowledge is still very limited. Testing this hypothesis will require intense controlled investigations.