Tag Archives: kidney transplant

Lasker Awards 2012: How animal research empowered the pioneers of liver transplantation

As a medical student in 1950 one of my patients was a boy of my age dying of kidney failure and I was instructed to make him comfortable for he would be dead in two weeks. I asked if he could have a graft of a kidney and I was told “no” and then when I asked “why” the subject was dismissed with the words “it can’t be done.””

These are the opening words of the acceptance remarks of Sir Roy Calne, Professor Emeritus at Cambridge University, after it was announced last month that he and Professor Thomas E. Starzl, of the University of Pittsburgh, would share the 2012 Lasker-DeBakey Clinical Medical Research Award For the development of liver transplantation, which has restored normal life to thousands of patients with end-stage liver disease”.

It’s an award that is well deserved by both Calne and Starzl, since not only did their work help to prove within a few years that kidney grafts “be done” (for which Joseph E. Murray, E. Donnall Thomas were awarded the Nobel Prize in Physiology or Medicine in 1990) but they then went on to show that the liver, considered to be a more difficult organ to transplant due to its greater complexity, could also be transplanted. As a consequence of the work of Calne and Starzl more than 50,000 people are alive today who would otherwise died from end-stage liver failure. The Lasker Foundation have produced an excellent video to accompany the awards, which includes interviews with both scientists, and can be viewed on their website here.

Image courtesy of the Lasker Foundation

And how did animal research contribute to the development of liver transplant surgery?  Well, the truth is that it would take too long to detail in this post all the key contributions that operations performed on dogs by Thomas Starzl made to the development of the surgical techniques required, and the animal studies undertaken by both Calne and Starzl that allowed them to develop the first immunosuppressant therapies to prevent rejection.

To learn about how they moved from the lab to the clinic and then back to the lab again you can read the award description, which also highlights how transplant survival improved dramatically after the introduction of improved immunosuppressants. These included Cyclosporin A, discovered through studies of immunosuppressant activity in mice by Jean-Francois Borel at Sandoz Laboratories, and Campath-1H/Alemtuzumab, a humanized rat monoclonanal antibody whose development by Hermann Waldmann and colleagues at Cambridge University was prompted by studies in mice, dogs and monkeys, and whose subsequent development relied heavily on studies in mice.

Image courtesy of the Lasker Foundation

If you would like to know more, Professor Calne has written a lively essay on his work transplants entitled “It can’t be done”, while Professor Strazl’s perspective on their work and the insights into the functioning of the immune system that they gained is titled “The long reach of liver transplantation”. Both essays are well worth reading, and highlight an important fact; animal studies alone can’t perfect a therapy, and neither can clinical studies, it is the close interplay between the two that leads to breakthroughs in medicine.

As we congratulate Sir Roy Calne and Professor Thomas Starzl on winning this prestigious award, it is worth remembering that animal research continues to make a crucial contribution to the development of new transplant techniques, from the bioengineered tissues that are beginning to transform transplant surgery, to the spermatogonal stem cell transplants that we discussed on this blog only last week.

Paul Browne

The new face of transplant surgery, thanks to animal research

Yesterday the University of Maryland Medical Center (UMM) announced most extensive full face transplant completed to date, including both jaws, teeth, and tongue. In a marathon 36-hour operation the surgical team led by Professor Eduardo Rodriguez were able to transplant a face of an anonymous donor onto their patient Richard Lee Norris, who had been injured in a gun accident 15 years ago.  The operation was the culmination of years of clinical and animal research undertaken at UMM under the leadership of Professor Stephen Bartlett, and funded by the Department of Defense and  Office of Naval Research due to its potential to help war veterans who have received serious facial injuries.

This successful operation, termed a vascularized composite allograft, was made possible not only by the selflessness of the family of the anonymous donor, but also by the years of animal research undertaken by Professors Rodriguez and Bartlett and colleagues. For example, a key factor in the success of this operation was that they transplanted high amounts of vascularized bone marrow (VBM), which came inside the transplanted jaw, a technique that was developed by the team after observing that tissue rejection following composite tissue allotransplantation in a cynomolgus monkeys was greatly reduced when VBM was included in the transplant. This discovery will also help to reduce the amount of immunosuppression that Mr. Norris and future patients require following facial transplants.

Of course this is far from the first contribution that animal research has made to transplant surgery, from the development of the techniques of kidney transplant through research in dogs by Joseph Murray and colleagues, to the careful experiments in dogs conducted by Norman Schumway and Richard Lower that led to the first successful heart transplants, to the studies in mice and rats that identified the immunosuppressive properties of the drug cyclosporin that transformed the transplantation field in the 1980’s, animal research has made a crucial contribution to this field. Indeed, in his 1990 Nobel Lecture Edward Donnall Thomas stressed the importance of animal research to his Nobel prize winning discoveries concerning bone marrow transplantation.

Finally, it should be noted that marrow grafting could not have reached clinical application without animal research, first in inbred rodents and then in outbred species, particularly the dog.”

Animal research continues to make key contributions to transplant science, and we have had several opportunities to discuss its role in the development of lab-engineered tissues for transplant, such as the artificial bladder, on this blog.

Yesterday’s news from the University of Maryland is another reminder that animal research is still crucial to advances in transplant surgery. It is also worth remembering that when animal rights groups attack animal research conducted by the Department of Defense, it is work such as that which led to yesterday’s breakthrough that they are attacking.

Paul Browne

From Mouse to Monkey to Humans: The Story of Rituximab

Modern advances in science have meant that our models of diseases have vastly improved. Be that in a dish in the laboratory, a computer simulation or through using a transgenic mouse, there have been developments across the biomedical field that have given us a greater understanding of diseases and how our bodies work.

This increase in knowledge has meant that we are finding may drugs already on the market can treat a variety of diseases – those involving the same pathway or cell type. This is precisely what happened this month with a drug called Rituximab.

Rituximab was licensed in 1997 for use in the treatment of Non-Hodgkin’s lymphoma (NHL) – a cancer where cells of the immune system called B-cells mutate and divide abnormally. The cancer then spreads around the body when the B-cells clone themselves in replication.

Since it’s initial approval for use in NHL, rituximab has been used to successfully treat advanced rheumatoid arthritis and has also been part of anti-rejection treatments for kidney transplants (both involve B cells. Then news came last week that it could even slow the progression of rheumatoid arthritis (RA) in the early stages of the disease.

Rheumatoid Arthritis

Rituximab is an interesting drug, as it is a chimeric antibody. This means that it contains portions of both human and mouse antibodies mixed together. The first papers reporting on rituximab were published in 1994. The first looked at its creation, and the second reported on the phase I clinical trials of the drug.

The human immune system works by using antibodies as their ‘messengers’. The antibodies contain multiple regions that allow them to work effectively. One part of the molecule binds with the foreign molecule; the other part then recruits the immune cells to destroy the molecule and eliminate it from the body.

The B-cells mutated in NHL and involved in RA are part of the human immune system and are responsible for making antibodies against ‘foreign invaders’. Mature forms of B-cells have a protein called CD20 on their surface.

The protein CD20 was the target for a team in San Diego (1) in 1994. Because NHL and RA are characterised by excessive levels of, or mutated B-cells, they looked at ways to reduce their numbers. The researchers determined that CD20 was the perfect target on the human B-cells as it was located on the surface of the cell and it didn’t mutate, move inside the cell or fall off in the life cycle of the B-cell. The team then produced an antibody that would attack CD20 itself, so it would bind to the outside of B-cells, flagging them to the immune system to be eliminated. They identified a mouse antibody that had high anti-CD20 activity.

They then constructed a “chimeric” antibody containing the variable domain of the mouse antibody, the portion that specifically binds CD20, along with the constant domain of human antibody, the portion that recruits other components of the immune system to the target.

The construction of a chimeric antibody (later named rituximab) was crucial, as the mouse antibody was unsuitable for direct use in humans. While the mouse antibody was able to bind to human CD20, it would not be able to then recruit the human complement system and immune cells that are needed destroy the “targeted” B cells. It would also quickly be recognised as foreign in the human body, and destroyed by the immune system, therefore by using a chimeric antibody with enough human characteristics, the antibody would not only recognise the human CD20 and target the immune system to it but would remain in the body long enough to destroy the B cells.

To test whether rituximab would work as hoped, they performed studies in cynomolgus monkeys. They choose this species because the constant domains of their antibodies are very similar to those in humans, unlike those of the mouse, allowing the chimeric antibody to function as it would in humans. Following administration of rituximab the number of B cells in the monkey’s bloodstream fell dramatically. The numbers were also reduced in the bone marrow (where B cells are produced) and the lymph nodes (where they are activated to target foreign molecules). Rituximab administration was non-toxic and in the weeks after treatment finished the number of B-cells slowly recovered. This is important as it demonstrates that the treatment didn’t harm the monkey’s bone marrow stem cells, an important consideration since these cells are required for a healthy immune system.

Rituximab was an ideal candidate to treat NHL and the promising results in monkeys prompted the scientists to conduct phase I clinical trials inhuman patients which confirmed that rituximab was safe and indicated that it could shrink tumors.

Evaluation of the effectiveness of rituximab involved many studies of patients with Non-Hodgkin’s lymphoma. While the initial clinical trial results varied, likely due to the differing sizes of tumors between the patients, they showed it was effective at reducing B-cell numbers and tumor size. Since it’s approval numerous clinical trials have confirmed that rituximab is an effective treatment for Non-Hodgkin’s lymphoma (3).

This month’s exciting study by Professor Paul-Peter Tak from the University of Amsterdam showed that rituximab in combination with the drug methotrexate could slow the progression of early stage rheumatoid arthritis (RA).

The study involved 755 patients diagnosed with RA within the last year. Methotrexate is already considered to be the best treatment for these patients and 12.5% of the patients taking only methotrexate in this study experienced significant reduction of their symptoms. However, compare this to the 30.5% of patients taking a combination of methotrexate and rituximab, and it is clear that rituximab is effective. Issues of cost have been raised in relation to rituximab, but if it turns out to be as effective in treating early RA as this study suggests, then it may ultimately save the health services and insurance companies money as slowing or stopping the progression of the disease will result in fewer patients needing the more expensive treatment and care required in advanced RA.

Emma Stokes

1) Reff M.E. et al. “Depletion of B cells in vivo by a chimeric mouse human monoclonal antibody to CD20.” Blood Volume 83(2), Pages 435-445 (1994) PubMed: 7506951

2) Maloney D.G. et al. “Phase I clinical trial using escalating single-dose infusion of chimeric anti-CD20 monoclonal antibody (IDEC-C2B8) in patients with recurrent B-cell lymphoma.” Blood Volume 84(8), Pages 2457-2466 (1994) Pubmed: 7522629

3) Schultz H. et al. “Chemotherapy plus Rituximab versus chemotherapy alone for B-cell non-Hodgkin’s lymphoma.” Cochrane Database of Systematic Reviews 2007, Issue 4. Art. No.: CD003805. DOI:10.1002/14651858.CD003805.pub2.