Expression of pancreatic duodenal hoemobox-1 in pancreatic islet neogenesis after surgical wrapping in rats.

BACKGROUND

Surgical wrapping (SW) of the pancreas causes islet neogenesis in rodents. Pancreatic duodenal hoemobox-1 (PDX-1) is one of the transcriptional factors needed by pancreatic stem cells to develop a mature pancreas. The purpose of this study was to determine whether islet neogenesis arises from ductal cells and whether PDX-1 is involved in this process.

METHODS

SW consisted of nonocclusive wrapping of the pancreas in rats. The wrapped pancreas was then harvested, insulin content was measured, and immunohistochemical analysis for insulin, cytokeratin, and PDX-1 was performed.

RESULTS

The endocrine area of the wrapped pancreas significantly increased after SW. Double immunostaining identified cells positive for both insulin and cytokeratin in or along the epithelial cell lining of the ductal structures and in the centroacinar cells. PDX-1-positive cells were detected in both control islets and islets examined after SW, but these cells were observed in the exocrine area only after SW. Double staining also showed that cells positive for PDX-1 but negative for insulin were present in the exocrine area 1 day after SW and that cells positive for both PDX-1 and insulin had developed 3 days after SW.

CONCLUSIONS

In the process of adult islet neogenesis after SW, cells in the acini and ductal structures developed into PDX-1-expressing cells, supposedly progenitor cells, which in turn became insulin-producing cells and thus might be the origin of small islets.