Stem cell therapy may remove the need for organ transplant recipients to have lifelong drug treatment to combat the risk of rejection, which would dramatically improve patients' quality of life.
A new therapy technique has been trialled in eight US kidney transplant patients and early results have been published in the journal Science Translational Medicine. One year after the transplant five of the patients managed to avoid taking the usual immunosuppressive medication and two patients were taking lower doses of these drugs than would normally be required. One patient developed viral sepsis – an occasional complication of organ transplantation – and had to have their new kidney removed again.
Dr Suzanne Ildstad, of the University of Louisville, who led the study, said: 'Immunosuppressive medications come with serious side effects with prolonged use including high blood pressure, diabetes, infection, heart disease and cancer, as well as direct damaging effects to the organ transplant. This new approach would potentially offer a better quality of life and fewer health risks for transplant recipients.'
The stem cell therapy effectively alters patients' immune systems, so that they do not recognise the transplanted kidneys as 'foreign' and reject them.
In the technique, the kidney donor is given medication to boost the number of bone marrow stem cells in their blood a month prior to the operation, and a blood donation is collected. The blood is processed to increase both the numbers of stem cells and another cell type the researchers called transplant 'facilitating cells', and frozen until needed.
The kidney recipient then undergoes radiation and chemotherapy to disable their own immune systems in a manner similar to treatment given to leukaemia patients prior to bone marrow transplants. The kidney is then transplanted and one day later the recipient receives a transplant of the stem cells and facilitating cells collected from the donor.
The transplant patient is then prescribed a usual regime of immunosuppressive drugs, but after six months is gradually weaned off them if the stem cell transplant has been successful.
Dr Tatsuo Kawai, a transplant surgeon at Harvard Medical School, who was not involved in the study, wrote a commentary on the new approach in the same journal. He lauded the results, but also said that it was hard to tell from the study how important the facilitating cells were, as there had been no control group where patients underwent the procedure without receiving these cells.
He also added that subjecting transplant patients to a treatment as harsh as radio- and chemotherapy should be carefully considered, especially as the current techniques for kidney transplantation are relatively safe and well understood.