Poster (remastered edition, 2025) presented at the 3rd IPITA Congress, June 1991, in Lyon, France (1). One of three posters presented at this congress on purification during the isolation of pancreatic islets (1,2,3,4).

Background

Purification during the isolation of pancreatic islets was greatly improved in 1989 by replacing the conventional islet isolation solutions with the UW organ preservation solution.

The UW-Solution was used as the isolation solution both before , and after the purification of islets — but not yet during the purification step, during centrifugation of the pancreatic tissue in a density gradient.

A conventional (Hanks’ balanced salts) solution was used for preparing density gradients with dextran, the Minneapolis method introduced in 1988 in our laboratory (5).

We had demonstrated previously, that the use of the UW organ preservation solution for isolation of canine pancreatic islets prior to dextran gradient purification, consistently results in >90% purified islets. Further 4 out of 5 islet transplants purified using this gradient had been successful.

Following our islet transplants series June-August 1989 , next a working visit in Minneapolis Sep-Oct ’89, and presentations at the Nov ’89 ESOT congress in Barcelona , we had started a new series of islet isolation experiments from December 1989.

During the first two isolations, Dec 1989, of this new series, I wondered whether the dextran gradient could be optimized , for example by layering the islet suspension in UW-Solution (the pancreatic digest suspension) on top of the dextran bottom layer, or perhaps layering the digest on top of a bottom layer of dextran dissolved in UW-Solution…

The new , much shorter, Labcraft density hydrometers, I had purchased during the Minneapolis visit Nov. 1989 , would greatly facilitate designing new density gradients.

The same lot of dextran (Sigma’s industrial-grade dextran) had been used for all these studies. That stock ran out, so a switch was made Jan 2, 1990 to using a new batch of that dextran powder, resulting however in a significantly impaired recovery of islets during purification , as shown in the poster shown here.

Thus, designing a new density gradient became urgent January 1990.

Dextran UW Gradient • First density gradient in UW-Solution

March 6, 1990 , new density gradient research was started during islet isolation , splitting the suspension of digested pancreatic tissue (‘digest’) for comparison of either dextran of Ficoll (a similar product) in Hanks’ solution , and also a dextran gradient in UW-Solution – the first ‘UW gradient’…

Later that month, purification research was started with a different, essentially pure, dextran product : ‘dextran T70′ from Pharmacia, in Hanks’ solution — with results reported in the poster here.

From April 1990, dextran T70 was used also in dextran-UW gradients, and islet purification research was further extended that month, by designing a density gradient of Percoll in UW Solution (3), and from May 1990, designing a Pentastarch-UW gradient (4).

Notes

1) Van der Burg MPM, Guicherit OR, Scherft JP, Frölich M, Gooszen HG. Sigma’s industrial grade dextran is not suitable for islet isolation. 3rd International Congress on Pancreatic and Islet Transplantation, Symposium on Artificial Insulin Delivery System, Lyon (France) June 6–8, 1991.

2) Dextran UWS Pancreatic Islet Purification • 20250104 • Michel van der Burg • michelvanderburg•com

3) Percoll UWS Pancreatic Islet Purification • 20240731 • Michel van der Burg • michelvanderburg•com

4) PentaStarch UWS Pancreatic Islet Purification • 20240802 • Michel van der Burg • michelvanderburg•com

5) Pancreas & Islet Transplantation Program • 20240912 • Michel van der Burg • michelvanderburg•com

Citation info : Dextran UWS Pancreatic Islet Purification • Michel van der Burg • Miracles.Media • @1MEMO 20250104 • URL michelvanderburg.com/2025/01/04/