Innovative Islet Purification in Iodixanol-UWS • IPITA 97 • @1MEMO 20250128

No porcine islet loss during density gradient purification in a novel iodixanol in University of Wisconsin solution. First talk on our introduction of the innovative Iodixanol-UWS density gradients for islet purification , showing no islet loss in the difficult model of pig islet isolation — presented at the 6th IPITA congress in Milan (Italy) , Thursday, 25th september 1997 (1).

Background

In 1995 the Leiden Islet Lab had moved into the Surgery Lab in the new LUMC building, and the islet team had grown, focussing on xenotransplantation. With more people isolating pig islets, more convenient islet isolation solutions were tried.

Both Percoll-UWS (2) and Histopaque-UWS (3) were being used from 1992 in first series of islet isolations from juvenile pig pancreases.

August 1995, I started designing the clinical promising islet purification solution of Iodixanal in UW-Solution (UWS). I mixed Optiprep – a 60 % solution of iodixanol in water – with a 2-times concentrated UWS, to prepare this density gradient solution. The first standard operation procedure of this Iodixanol-UWS gradient for our pig islet isolation research was completed November 1995.

This purification solution was a logical follow-up of our highly succesful Percoll-UWS density gradient (2) — a similar solution of impermeants (that do not readily enter cells) with similar osmolarity (close to that of the tissue) , more practical though, and with the important advantage that iodixanol is clinical tested.

July 1996, I introduced the Iodixanol-UWS gradient to replace the Percoll-UWS gradient for large scale pancreatic islet research in this difficult model of islet isolation from juvenile pig pancreases.

The work was presented September 1997. First a poster was presented that month at the Xenotransplantation Congress in Nantes , France (4). Next, two talks followed at the 6th Congress of the International Pancreas and Islet Transplant Association (IPITA) in Milan (Italy).

Here the (remastered) slideshow of that first talk at the 6th IPITA Congress in Milan, presented Thursday, 25th september 1997 (1) . The slideshow of the 2nd talk , presented at the last day of that congress, was posted yesterday (5).

Notes

1) Van der Burg MPM, Basir I, Bouwman E. No porcine islet loss during density gradient purification in a novel iodixanol in University of Wisconsin solution. Sixth Congress of the Int. Pancreas and Islet Transplant Association (IPITA), Milan (Italy) Sept. 24–27, 1997.

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

3) Basir I, van der Burg MPM, Scheringa M, Töns A, Bouwman E. Improved outcome of pig islet isolation by Pefabloc inhibition of trypsin. Transplant Proc. 1997 Jun;29(4):1939-41. doi: 10.1016/s0041-1345(97)00168-1. PMID: 9193462

4) Van der Burg MPM, Basir I, Bouwman E. Non-traumatic porcine islet density gradient purification in a novel iodixanol in University of Wisconsin solution. The 4th Int. Congress for Xenotransplantation, Nantes (France) Sept. 7–11, 1997. Online in : Purification Islets in Iodixanol-UWS • Leiden Start 1996 • Michel van der Burg • Miracles.Media • @1MEMO 20250126 • URL michelvanderburg.com/2025/01/26/

5) Van der Burg MPM, Basir I, Zwaan RP, Bouwman E. Porcine islet preservation during isolation in University of Wisconsin solution. Sixth Congress of the Int. Pancreas and Islet Transplant Association (IPITA), Milan (Italy) Sept. 24–27, 1997. Online in : Porcine Islet Preservation In UWS • IPITA 97 • Michel van der Burg • Miracles.Media • @1MEMO 20250127• URL michelvanderburg.com/2025/01/27/

Milan Papers • @1MEMO 20250205 • Manuscripts (Preprints) and Abstracts copies of the presentations at the IPITA 1997 meeting in Milan (Italy). PDF downloads at michelvanderburg•com/2025/02/05/

Citation info : Innovative Islet Purification in Iodixanol-UWS • IPITA 97 • Michel van der Burg • Miracles.Media • @1MEMO 20250128 • TakeNode • URL michelvanderburg.com/2025/01/28/

Porcine Islet Preservation In UWS • IPITA 97 • @1MEMO 20250127

This purification solution was a logical follow-up of our highly succesful Percoll-UWS density gradient — a similar solution of impermeants (that do not readily enter cells) with similar osmolarity (close to that of the tissue) , more practical though, and with the important advantage that iodixanol is clinical tested.

The Leiden Islet Lab had just moved into the Surgery Lab in the new LUMC building, and the islet team had grown, focussing on xenotransplantation. With more people isolating pig islets, more convenient solutions were tried.

Both Percoll-UWS and Histopaque-UWS were being used from 1992 for small scale islet isolations from juvenile pig pancreases.

July 1996, I introduced the Optiprep-UWS gradient to replace our Percoll-UWS gradient for larger scale porcine islet isolations.

The work was first presented September 1997, both in a poster presented at the Xenotransplantation Congress in Nantes , France (1), and later that month in two talks at the 6th Congress of the International Pancreas and Islet Transplant Association (IPITA) in Milan (Italy). The slideshow of the first talk (2) will be online at this site soon.
Here the remastered slideshow of the 2nd talk at the 6th IPITA Congress in Milan, presented Saturday, 27th September, 1997 (3).

Notes

1) Van der Burg MPM, Basir I, Bouwman E. Non-traumatic porcine islet density gradient purification in a novel iodixanol in University of Wisconsin solution. The 4th Int. Congress for Xenotransplantation, Nantes (France) Sept. 7–11, 1997. Online in : Purification Islets in Iodixanol-UWS • Leiden Start 1996 • Michel van der Burg • Miracles.Media • @1MEMO 20250126 • URL michelvanderburg.com/2025/01/26/

2) Van der Burg MPM, Basir I, Bouwman E. No porcine islet loss during density gradient purification in a novel iodixanol in University of Wisconsin solution. Sixth Congress of the Int. Pancreas and Islet Transplant Association (IPITA), Milan (Italy) Sept. 24–27, 1997.

3) Van der Burg MPM, Basir I, Zwaan RP, Bouwman E. Porcine islet preservation during isolation in University of Wisconsin solution. Sixth Congress of the Int. Pancreas and Islet Transplant Association (IPITA), Milan (Italy) Sept. 24–27, 1997.

Update 20250128 – update intro design timeline

Update 20250205 – added Milan papers

Citation info : Porcine Islet Preservation In UWS • IPITA 97 • Michel van der Burg • Miracles.Media • @1MEMO 20250127 • TakeNode 6d6fca2e-014c-40cf-8110-725b267c0b0e • URL michelvanderburg.com/2025/01/27/

Percoll UWS Purification Pancreatic Islets • ESOT 1991 Talk • @1MEMO 20250114

Percoll UWS Purification Pancreatic Islets • ESOT 1991 Talk • Michel van der Burg • Miracles.Media • @1MEMO 20250114 • TakeNode 459d71fd-069f-4f6d-9c8f-924ebf132222

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.

Cassette Tapes , Audio Archives Int, 5th ESOT • Michel van der Burg • Miracles.Media • @1MEMO 20250114_2 • TakeNode 97730a39-b3db-4f56-a08a-77c4d0406be0

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/

Dextran Density Purification Of Pancreatic Islets • @1MEMO 20250104

Dextran Poster 3rd IPITA 1991 • Michel van der Burg • Miracles.Media • 20250104_1 • TakeNode 1c05b2a5-de41-4185-b304-fee2335100f3

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.

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.

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.

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/