The Separation of Cell Suspensions Isolated from Coelomic Fluid and Coelomic Epithelium of the Starfish Asterias rubens in Percoll Density Gradients

The regeneration process assumes the presence in the body of cells capable of self-renewal and subsequent differentiation into specialized cells. Whether these cells are stem cells or are present in circulating fluids or tissues as a pool of reserve progenitor cells, or whether they appear following dedifferentiation/transdifferentiation of specialized cells of individual tissues, are the main questions that scientists are focusing on. Understanding the origin and pathways of differentiation in coelomic fluid cells and coelomocytes of the starfish Asterias rubens was the aim of this research. The coelomic epithelium is considered as a possible source of coelomocytes. Further effective studies of coelomocyte replenishment are difficult due to the lack of protein markers characterizing various cell morphotypes. Additional difficulties lie in the heterogeneity of analyzed cell populations. In the present study, we separated cells of the coelomic fluid and the coelomic epithelium, and a subpopulation of the coelomic epithelium enriched with poorly differentiated cells, which are proposed precursors of some types of coelomocytes, in a Percoll density gradient. Characterization of the cell morphology of different fractions and their behavior in vitro (functional characteristics) revealed an enrichment of the gradient fractions in two of eight types of coelomocytes and three of eight morphotypes of cells of the coelomic epithelium.