Our first collaboration with Dr. Rilo's group at the University of Chicago was productive and exhausting. We made eight sheets of two types with islets of Langerhans from three dogs. One non-diabetic dog received four sheets made from the dog's own islets to find out which implant sites are good for sheets. This dog was our "sound science" experiment, guaranteed to advance our project. By using a nondiabetic dog that received its own islets, we controlled all variables except the one of interest, the sheet location. The other recipient was our risky attempt to "go for it" and cure a dog of diabetes on the first try! Although we did not succeed at the level of our highest hopes we are encouraged by the results we did get.
We arrived Tuesday, September 8. One of us (Scott King) is a graduate of the University of Chicago; it was good to be back in Hyde Park. We met Dr. Rilo, and he reported that the morning's pancreatectomy had gone well. He had removed 99.5% of the pancreas, so the dog was guaranteed diabetic. We unpacked and prepared to make sheets. (Rick Storrs and Randy Dorian of Islet Sheet Medical are shown at left.)
We were confident of success (perhaps too confident), but we had never made sheets containing islets. Up to this time we had always used sham islets. In case there were unexpected difficulties, we had decided to do the autograft second, and try for the cure first. On Wednesday, Dr. Rilo's group isolated islets from two mongrel dogs. (Alizah Rotramel and Ningfang Chen are pictured at right.) The isolations went very well. The yield was high, and because both donor dogs were larger than the pancreatectomized dog recipient, there were many more islets than the minimum needed to cure the dog.
Dr. Horacio Rodriguez Rilo with the fresh dog islets.
Creation of the first Islet Sheets took place from 11:00 P.M. Wednesday to 3:30 A.M. Thursday. It did not go entirely well. These sheets were made with a mesh reinforcement. Sheets without islets were strong enough without the mesh, but we did not know how much the presence of islets would weaken the sheet. The mesh would guarantee structural integrity.
The islets from the first donor dog arrived, and we made two good mesh-containing sheets. The "mesh" process had worked well. As we were we relaxing, waiting for the second batch of islets, Randy remembered that there was some potential problem with the cell culture medium we had used to feed the islets until they were implanted. Back in the laboratory our worst fears were realized: there was a cloudy precipitate that we knew indicated that the islets in the sheets were damaged.
After getting a different bottle of culture medium that is compatible with Islet Sheets, we started making two more sheets with the second batch of islets. But for reasons we still don't entirely understand, the same process now failed - the sheets literally fell apart. One half of one sheet was salvaged, and looked good. The other sheet was a total loss.
This was depressing. We had succeeded with only 1/8 of the precious islets. Thursday morning we reviewed the situation with Horacio, and decided to put the good half-sheet into the best spot in the dog, and also to put in the two sheets with damaged islets. While he did the implant Randy and Rick set to work to find out what had gone wrong. We suspected that the mesh was part of the problem. And the one piece of good news from the night before was that it was clear that the sheet was strong enough without a mesh reenforcement. All night Thursday we worked on new methods for fabrication of sheets without mesh reenforcement.
We can't tell you much about the feverish inventions of that day except some surprising things worked well. At the left you see a diffusion control membrane so thin that it is birefringent. At 5:00 we all met, and decided to proceed with the planned autograft experiment. Randy thought that two or three hours more work would make the newly evolving methods work. Horacio said he would come in early, do the hemi-pancreatectomy, and have the islets ready by 10:00 A.M. Friday. The dog would remain in the operating room until the sheets were ready to implant.
It turned out that 2-3 hours was not enough. Rick and Randy were in the laboratory until 5:30 A.M. Friday. After a brief sleep, we prepared to make mesh-less "gossamer" sheets. The islets arrived midday and all four were in the dog by mid-afternoon. All four sheet fabrications went well.
The first "gossamer" Islet Sheet ever made.
We were too numb from lack of sleep to know whether we had succeeded or failed. At dinner Horacio reflected that he thought the experiments went well. He had decided that he would not use any injected insulin to treat the diabetic dog. We would depend on the sheets alone. In his view this is the cleanest experiment.
After separate sightseeing adventures in Chicago we returned to San Francisco. After two weeks it was clear that the sheets were functioning, but not well enough to cure the dog. After about a month the dog was sacrificed and the sheets removed for analysis.