Morphological observation of pancreatic stem cells and umbilical cord blood mesenchymal stem cells cultured in vitro

ABSTRACT

BACKGROUND:

Stem cells are relatively primitive cells possessing the capabilities of self-renewal, high proliferation and multi-potential differentiation in vivo under certain conditions. Pancreatic stem cells and umbilical cord blood mesenchymal stem cells (MSCs) may serve therapeutic purpose clinically, but they are still difficult to culture in vitro at present.

To explore the method for isolation, purification and culture of pancreatic stem cells and umbilical cord blood MSCs in vitro and observe their morphological changes during culture in vitro.

Completely randomized experiment with repeated measurement.

Stem Cell Research Center, Teaching and Research Division of Physiology, Medical School of Zhengzhou University.MATERIALS This experiment was conducted in the Stem Cell Research Center, Teaching and Research Division of Physiology, Medical College of Zhengzhou University, between April 2004 and January 2005. Ten to fifteen newborn SD rats (1-3 days) were selected for culture in vitro of pancreatic stem cells, and fresh umbilical cord blood was collected from healthy woman (24-35 years old, with informed consent) at full-term delivery for culture in vitro of umbilical blood SMCs.

The abdomen of the newborn SD rat was opened under aseptic condition to obtain the pancreas, which was cut into small tissue blocks and digested with type-V collagenase for islet isolation. The isolated islets were purified in continuous roller-bottle culture. Umbilical cord blood was freshly collected for isolating the monocytes by means of density gradient centrifugation in lymphocyte separation medium (with density of 1.077 g/cm3). The islet cells and umbilical cord blood monocytes were cultured in the incubator at 37 ℃ with 5% CO2. The morphological changes of the cells were observed at designed time points and flow cytometry was used to determine the expression of cell surface molecules.MAIN OUTCOME

The isolation and culture of pancreatic stem cells and umbilical cord blood MSCs, and their morphological changes during culture in vitro.

During culture in vitro, the fusiform islet progenitor cells showed adherent polar growth and continuous proliferation, which covered the whole bottom of the flask after 12-14 days and could be subcultured for passages. However round cells appeared after removal of the growth factor and serum in the culture medium. The monocytes isolated from the umbilical cord blood grew initially into numerous hematopoietic cell clones, most of which proved to be granulocyte clones by Switzerland staining. Seven days later, flat flask wall-adhering epithelial cells and long fusiform fibroblasts were observed mixed with a number of osteoclasts. As the cell culture was prolonged, the cell number increased steadily.

Pancreatic stem cells and umbilical cord blood SMCs can be cultured in vitro for further experiments.