Trends in Kidney Transplantation

Advances in kidney transplantation centre around balancing the immune system to a level where the kidneys are not rejected and at the same time warding it from infections

Dr R Balasubramaniyam

Kidney transplantation is one of the breakthroughs in medical science. In contrast to many surgeries where a diseased organ is removed from the body or repaired, kidney transplantation involves implanting a kidney from another person to the patient's body. The natural tendency of the human immune system is to reject any foreign tissue—be it a harmful bacteria or a life saving kidney. After transplantation, the immune system of the patient will reject the kidney in no time. In order to avoid this, patients are given immuno suppressive medicines, to slow down the immune process that will allow the kidney to function normally. Since we reduce the power of immune system, the patients are highly prone to infections and can cause life-threatening infections if left undiagnosed. So, the greatest job of the nephrologist is to balance the immune system to a level where the kidneys are not rejected and at the same time keep the immune system at a level where the infections are kept under control. This is akin to walking on a tight rope.

The last few years witnessed significant improvisations in kidney transplantation. They can broadly be categorised into the following:

• Introduction of newer immuno suppressive drugs to increase the success rates of transplantation.
• Steps to increase the donor availability—by doing ABO incompatible transplantation and by performing transplants from non-heart beating donors.
• Kidney removal from the donor through laparoscopic donor nephrectomy.

Newer Immuno Suppressive Drugs

One of the major challenges in kidney transplantation surgery is to make the kidneys function normally as long as possible. In the pre-cyclosporin era, where the basic immuno suppression consisted of azathioprine and steroids, the first year graft survival was about 50 per cent and the mortality rate of the transplanted patient was 10-20 per cent. The introduction of cyclosporin in the early 1980s had significantly increased the success rates to above 80 per cent at the end of one year. The last decade also witnessed the introduction of many immuno suppressive drugs including sirolimus, everolimus, tacrolimus and mycophenolic acid that increased the first year graft survival close to 90 per cent.

One of the major factors in determining the longevity of graft is the acute rejection episode. The newer immuno suppressives significantly decreased the acute rejection episodes, but not up to 100 per cent. Earlier, steroids were the only anti-rejection agents available. Though it still remains an important anti-rejection therapy, other newer agents including monoclonal antibodies-OKT3 and polyclonal antibodies were introduced to treat steroid non-responsive rejections. Newer drugs including a variety of monoclonal antibodies have been introduced recently. Basiliximab, daclizumab, Campath 1H are used as induction immuno suppressives and they have decreased the acute rejection episodes.

Though the introduction of newer drugs have decreased the acute rejection episodes and increased the first year graft survival, the long-term graft function has not been increased to a great extent. The graft loss is, basically because of immunological and non-immunological causes and death of the patient with the functioning graft. Calcineurin inhibitor drugs (cyclosporin and tacrolimus) by itself can lead to graft dysfunction and now the newer drugs have given the option of using calcineurin free protocols.

Increasing Donors

Though the number of transplants performed has increased significantly, the number of patients with End Stage Renal Disease (ESRD) needing a transplant has increased manyfolds. This has resulted in organ shortage. It has been estimated that over 30 per cent of the patients needing a transplant, have a near/close relative willing to be the renal donor but with an incompatible blood group. Like blood transfusion, renal transplantation also needs blood group compatible donors.

Till recently, transplants performed against the blood group antigens resulted in 'hyper acute rejection' of the graft, which is an irreversible damage to the transplanted kidney that happens within minutes after transplantation. But ABO incompatible transplants are successful today. Results indicate that the success rates are comparable to the routine transplants. This is another significant milestone in the history of transplantation.

Yet another method of overcoming the organ shortage is cadaver transplantation. Though the concept of brain dead and organ retrieval has been happening for a long time, organ retrieval from 'non-heart beating donors' have also started happening. Though this type of donation was practised before, it is given up today because of high failure rates and the global acceptance of brain death had resulted in decrease in organ retrieval from non-heart beating donors. With the increasing demand for organs, organ retrieval from 'non-heart beating donors' has come back with improvements, where organs can be successfully retrieved.

Laparoscopic Donor Nephrectomy

Earlier, in living donor nephrectomy, open surgery was the technique adopted. This resulted in pain and longer hospitalisation for the patients. Nowadays, the donor kidneys are removed by the laparoscopic method and donors are discharged on the third or forth day itself.

In the years to come, kidney transplantation will become more simplified and patients will have a good long-term success. But the most important factor is to prevent ESRD, which is best achieved by early identification and appropriate treatment of kidney diseases.

The writer is Head Kidney Transplant Centre KG Hospital Coimbatore
E-mail: rbs123@eth.net