Establishment of an in vitro culture system for intestinal epithelial cells from Pheretima aspergillum (E. Perrier)

The earthworm Pheretima aspergillum (E. Perrier) has been well documented as a traditional Chinese medicine. Earthworms possess fibrinolytic (Mihara 1991), anti-inflammatory and antipyretic activities (Balamurugan et al. 2009), and have been widely used by indigenous people worldwide, particularly in Asia, for their therapeutic properties. Previous studies have shown that earthworms can accumulate high concentrations of heavy metals within their tissues from a variety of metalcontaminated soils (Morgan and Morgan 1988; Morgan and Morgan 1999). Such accumulation of heavy metals poses a serious health threat to patients who are administrated the earthworm. Although the underlying mechanisms of bioaccumulation of heavymetals in earthworms have been investigated in vivo (Sturzenbaum et al. 2001), there is a need to develop a cell model for further study of biological absorption, distribution, metabolism, and the regulating mechanism. Currently, there is limited knowledge regarding earthworm cell culture. The first report of in vitro culture conditions for earthworm cells was for Lumbricus terrestris (Toupin et al. 1977). Subsequently, there was a study by Battaglia and Davoli (1997) concerning in vitro cell culture for Eisenia foetida . Unfortunately, no cell proliferation was recorded in these studies and subsequent attempts have failed to stimulate cell proliferation. Considering that heavy metals can easily enter the earthworms’s body by dietary intake and are then absorbed by mucosal epithelial cells of the intestine (Guo et al. 1998), the present study focused on optimization of culture conditions for intestinal epithelial cells from P. aspergillum . Our culture system might provide a useful model to better understand the mechanisms of heavy metal enrichment in earthworms.