In Vitro Stimulation of Hamster Pancreatic Duct Growth by an Extract Derived from the 'Wrapped' Pancreas

Partial obstruction of the hamster pancreas in the cellophane wrap model leads to the induction of duct and ductular proliferation followed by endocrine cell differentiation. This effect appears to be mediated by the local action of a growth factor. The purpose of the present study was to determine if cytosolic extract prepared from the wrapped pancreas had trophic activity on purified hamster pancreatic ductal epithelium in tissue culture. Cultures of purified pancreatic ducts were prepared by digestion of the hamster pancreas using a solution of collagenase type XI and chymotrypsin infused directly into the pancreatic duct. The ducts were separated and purified by a series of steel mesh filtrations. Ducts were embedded in 1.5% Seaplaque agarose and fed a liquid medium containing serum-free Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12 Ham (DME/F-12), 12.5% cytosol extract+DME/F-12, or 25% cytosol extract+DME/F-12. The trophic effect of the extract on the tissue in culture was evaluated by the incorporation of tritiated thymidine ([3H]TdR) into DNA. Duct fragments cultured in medium supplemented with 12.5% cytosol showed no difference in their [3H]TdR uptake compared with control ducts (908 +/- 147 vs. 913 +/- 151 dpm/micrograms DNA). The incorporation of [3H]TdR by ducts maintained in medium supplemented with 25% cytosol extract was increased 78% over serum-free controls (1,632 +/- 386 vs. 913 +/- 147 dpm/micrograms DNA; p < 0.025). We conclude that a cytosol extract prepared from the partially obstructed cellophane-wrapped pancreas contains a factor(s) trophic for pancreatic ductal cells.