Stem Cells Show Promise in Extending Transplanted Kidneys’ Survival Time

Can stem cells provide an answer to the perplexing question of how to ensure long-term survival of transplanted kidneys? The results of a new Phase 1 clinical trial say maybe so. Details of the trial, conducted by researchers at Leiden University Medical Center, The Netherlands, are published in the current issue of STEM CELLS Translational Medicine.

Kidney transplants have long been the treatment of choice for many patients with end-stage renal disease, and the short-term results are excellent. But unfortunately, the viability of these kidneys over time has not improved accordingly, often due to fibrosis, which is a scarring of the transplanted organ generally caused by the immune system rejecting it.

The LUMC team, led by Marlies E.J. Reinders, M.D, Ph.D., and Ton J. Rabelink, M.D., Ph.D., decided to test whether stem cells might keep fibrosis in check. They focused on mesenchymal stromal cells, a type of stem cell found throughout the body, including in bone marrow.

“Mesenchymal stromal cells (MSCs) are an interesting candidate due to their immunosuppressive and regenerative properties,” Dr. Reinders explained. “Of importance, no clinical studies have investigated their effects on rejection and fibrosis in organ transplantation.”

The team performed a safety and feasibility study in kidney transplant patients who, at four weeks or six months after transplant, were showing signs of rejection and/or an increase in fibrosis and wasting away of the kidney’s tubes (a condition called interstitial fibrosis/tubular atrophy. . In all, six patients received two intravenous MSC infusions of 1 million cells, collected from the patient’s own bone marrow and given one week apart. None of the patients had any sign of adverse, treatment-related side effects from the MSCs, although three developed infections associated with immune suppression.

Five of the patients had a specific decrease in immunity against the transplanted organ. In agreement, prior to the infusions, two of the patients had tubulitis — lesions that are a warning sign of organ rejection — which disappeared after the MSC treatment.

“These first clinical observations support the potential of stem cells as a novel cell therapy to prevent allograft rejection and interstitial fibrosis/tubular atrophy,” Dr. Rabelink noted, adding that long-term follow-up to better understand MSC-based treatment and to monitor unwanted side effects is needed, especially since transplant recipients are already at an increased risk for infection and malignancies.

“While the study wasn’t designed to test efficacy, these clinical observations are promising and suggestive of systemic immunosuppression,” said Anthony Atala, M.D., Editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.

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The full article, “Autologous bone marrow-derived mesenchymal stromal cells for the treatment of allograft rejection after renal transplantation: results of a phase I study,” can be accessed at http://stemcellstm.alphamedpress.org/content/early/2013/01/23/sctm.2012-0114.abstract.