Two years, after we introduced the UW-Solution ( UWS ) as the islet isolation solution at the 4th ESOT meeting (1,2) , this talk on the innovative Percoll-UWS density gradient for the purification of canine and human pancreatic islets, was presented at the 5th ESOT — Wednesday Oct 9 , 1991, at 2 PM at the 5th ESOT meeting in Maastricht, Netherlands (3) .

That 5th ESOT meeting was recorded on tape by Audio Archives Int. I purchased some tapes, including the tape of that afternoon session that had started with my talk — and found that the taping of this session had started a few minutes too late … during my talk, the moment I started presenting the Results.

That original tape is now included in this remastered slideshow of my talk presented in this video (20250114) here , starting at 2 min 51 sec.
Audio of the first part of my speech , missing in the original 5th ESOT tape, I have recorded this week (from the handout of the speech, written out at full lenght) and added as a voice over at the start of this remastered slideshow.

Background

In November 1989, I had my first chance for a presentation at a major international conference, the 4th ESOT meeting in Barcelona, of a paper centered on the rationale for employing the University of Wisconsin (UW) organ preservation solution in pancreatic islet isolation.

We demonstrated in 1989, that the use of the UW-Solution ( UWS ) for isolation of canine pancreatic islets prior to ‘conventional’ dextran gradient purification, consistently results in a greatly improved purification outcome, of >90% purified islets, and successful transplantation of the canine islets.

Thus , the UWS 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 still being used for preparing density gradients with dextran in our laboratory.

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 UWS (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 UWS…

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 (4).

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

Dextran-UWS Gradient • First density gradient in UW-Solution

March 1990 , new density gradient research was started during islet isolation , splitting the suspension of digested pancreatic tissue (‘digest’) for comparison of different density gradients, of either Sigma’s dextran, and Pharmacia’s essentially pure dextran T70 product in Hanks’ solution … and also the first ‘UW gradient’ tested : a dextran gradient in UW-Solution (4).

Percoll-UWS • Successful density gradient in UW-Solution

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, and from May 1990, designing a Pentastarch-UW gradient. Posters on these new density gradients in UWS were presented June 1991 at the 3rd IPITA Congress in Lyon, France (4,5,6).

The paper presented in this 5th ESOT talk, was presented the next year (1992) again in full detail in a poster at the 1st meeting of the Cell Transplant Society in Pittsburgh , and a remastered edition was posted online recently (7).

Proceedings paper below (8).

Slides originally created on a Macintosh computer October 1991, using the MacDraw II application, with graphs from Cricket Graph. Those 1991 files were remastered this month using LibreOffice, as well as the likewise produced Pittsburgh poster for this video of the 5th ESOT talk.
Handout speech and report files originally created in the Mac Desk Accessory ‘Acta’, currently accessed by Opal.

Notes

1) Pancreatic Islet Isolation With UW Solution • A New Concept • Michel van der Burg • Miracles.Media • @1MEMO 20241224 • URL michelvanderburg.com/2024/12/24/

2) Pancreatic Islet Isolation in UW Solution & Transplantation • ESOT 1989 Talk • Michel van der Burg • Miracles.Media • @1MEMO 20241229 • URL michelvanderburg.com/2024/12/29/

3) Van der Burg MPM, Guicherit OR, Prins FA, Scherft JP, Frölich M, Gooszen HG. Percoll in UW: efficient iso-osmotic canine and human islet purification. 5th Congres European Society for Organ Transplantation, Maastricht (The Netherlands) October 7–10, 1991.

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

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

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

7) Pittsburgh 1992 Cell Transplant Society • 20240812 • Michel van der Burg • michelvanderburg•com

8) Van der Burg MPM, Guicherit OR, Frölich M, Bruijn JA, Gooszen HG. Islet preservation during isolation: a new concept in cell transplantation. Transplant Proc. 1992 Dec;24(6):2840-1. PMID: 1465965. PDF available below
PMID_1465965 🔗

End Card

5th Congres European Society for Organ Transplantation, Maastricht (The Netherlands) October 9, 1991 14:00

0:07 Photo taken at 4th ESOT in Barcelona, 1989 (two years earlier)

0:06-2:51 Voice Over Michel van der Burg • Recorded Jan 11th, 2025 • Substitute for audio missing in original tape recording

2:51 Start Original Audio Tape 5th ESOT session by Audio Archives Int

6:52 Start Discussion • Chair : Reinout van Schilfgaarde (Groningen, Netherlands) • With contributions by Bernhard Hering (Giessen, Germany), R. Seelis (Edmonton, Canada), Derek Gray (Oxford, UK), and Reinout van Schilfgaarde (Groningen, Netherlands).

Citation info : Percoll UWS Purification Pancreatic Islets • ESOT 1991 Talk • Michel van der Burg • Miracles.Media • @1MEMO 20250114 • URL michelvanderburg.com/2025/01/14/