Isolation,purification and transplantation of rat islet cells

Sijiao CHEN; Teimin LI; Yangfeng LEI; Min WEI; Jindan SONG

ABSTRACT

BACKGROUND:

The islet cell transplantation has provided a solid basis for diabetic therapy, but the insufficient donor limits its development.

OBJECTIVE:

improving the method of isolating and purifying islets to observe the transplantation effect.

DESIGN:

A laboratory animal research.

SETTING:

Key Laboratory of Animal and Department of Cell Biology, China Medical University.MATERIALS The experiment was carried out in the Key Laboratory of Animal and Department of Cell Biology in China Medical University between January and October in 2006. Donors were Wistar rats of either gender, weight 250-300 g;Acceptors were SD male rats, weight 180-220g. The two kinds of rats were all common closed population and from the Experimental Animal Department of China Medical University (The Admission Number of Experimental Animal Institute is SYXK(LIAO)2003-0013).

METHODS:

①Isolation and exaltation of islet cells as well as the functional evaluation of pancreas After etherisation, the Wistar rat without fasting was executed. A little cut was made on the beginning of the biliary pore, then the little cut lumbar anesthesia ductus, which were connected with a 1-mm-diameter syringe and full of cold collagenase solution (1.5 g/L), was inserted directly to dilate pancreas thoroughly. The pancreatic gland was isolated and digested in the water of centrifuge, when doing that, 1 mol/L NaOH was put interruptedly into the centrifuge tube to keep the pH value of the solution at 7.8±1.0. The rat pancreas purified by centrifugation of Ficoll density gradient The identification of purified islets was evaluated by dithizone staining. The viability of islet was assessed by fluorescence staining of aridine orange and propidium iodide. The motility rate=the total number of live cells/(the total number of live cells + the total number of dead cells)×100%. Pancreatic activity was calculated insulin release index=the level of insulin at the third hour (high concentration glucose)/the level of insulin at the second hour (low concentration glucose). ②The blood from vena caudalis of SD rat was sampled and measured the blood sugar after the intraperitoneal injection of streptozocin. The rat was diagnosed as DM when blood sugar was more than 16.7 mmol/L twice without fasting. The DM rats were divided into two groups, every group 8 rats. The experimental group rats were injected about 1 000 islet cells into the location below renal capsule, and the control group rats were injected the same volume of 1640 cultu re solution. Eight normal rats, whose glucose concentration ≤ 5.5 mmol/L, were taken randomly as normal controlled group. The blood sugar was measured every day after the surgery. The blood sugar less than 11.1 mmol/L without fasting was taken as the sign of successful islet transplantation. Intravenous sugar tolerance test was applied to the rats of normal control group, DM control group and experimental group 3 days after islet transplantation. Fasting for 12 hours before test, the blood sugar was measured at 0, 15, 30, 60, 90 and 120 minutes.MAIN OUTCOME

MEASURES:

Purity quotient, survival rate and activity of islet cells.

RESULTS:

All 24 SD acceptor rats were involved in the result analysis without miss.①The total number of purified islets of one pancreas was (1 150±141) in well morphology. The purity of islets was more than 95%. The viability of islets was more than 98%. ②The insulin secretion response to glucose challenge in vitro showed the mean value of insulin in the low-glucose medium was (70.5±6.9) mlU/L, while that of high-glucose medium was (321.4±11.6) mlU/L, the insulin release index was 4.6±0.52, that meant the beta cell of islet functioned well. ③The blood glucose level and the insulin level in plasma of the transplanted recipients restored to normal 3 days after transplantation. The survival period of transplanted islets was (6±2) days. But there was not any change in the concentration of blood sugar in the control group (16.7 mmol/L). The intravenous glucose tolerance test showed the identical outcome between the islet splantation group and the normal control group.

CONCLUSION:

There are high yield and high purify of islet cells in rats, which are isolated by in situ perfusion and purified by Ficoll density gradient centrifugation.