Increasing the Safety of Stem Cell Interventions for Cancer

A recent study, published in the Journal of Clinical Oncology, demonstrates that the repeated infusion of mesenchymal stem cells could improve the safety of certain type of stem cell cancer therapies. Specifically, this approach could reduce dangerous graft-versus-host disease (cGVHD) symptoms in patients who have undergone a certain type of stem cell transplantation, known as HLA-haploidentical hematopoietic stem-cell transplantation (HLA-haplo HSCT).

While HLA-haplo HSCT can reduce the risk of relapse in leukemia patients, it is also associated with an immune reaction that is the leading cause of death in the patients that do not relapse. In these cases, the patient’s immune system mistakes the newly transplanted stem cells as dangerous foreign agents and attacks them. This reaction leads to organ damage and death.

Given that HLA-haplo HSCT can be effective against leukemia, researchers have wanted to find a way to increase its safety. This study was undertaken to determine if multiple infusions of mesenchymal stem cells could help the immune system learn to cope with the stem cells and minimize their reaction.

To test their idea, researchers studied 124 patients who had undergone HLA-haplo HSCT. They gave half of those patients multiple infusions of mesenchymal stem cells, and the other half received saline infusions known to have no effect. The researchers found that the patients who were given the mesenchymal stem cell infusions had a lower incidence of cGVHD than the patients who were given saline infusions.

Not only were the symptoms different between the group who received mesenchymal stem cell infusions and those who did not, but so too was the activity of immune cells. The mesenchymal stem cell infusions resulted in more memory B lymphocytes and regulatory T cells, both of which could help mitigate cGVHD symptoms. These infusions were also associated with fewer natural killer cells, which are important cells for immune cell reactions like cGVHD.

While more research is needed to determine exactly how mesenchymal stem cells should be used to prevent cGVHD and to what extent these cells can improve the safety of HLA-haplo HSCT, these results provide hope that leukemia patients will be able to more safely receive effective stem cell treatments in the future.

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Reference

Gao et al. (2016). Phase II multicenter, randomized, double-blind controlled study of efficacy and safety of umbilical cord-derived mesenchymal stromal cells in the prophyalxis of chronic graft-versus-host disease after HLA-haploidentical stem cell transplantation. Journal of Clinical Oncology, 34(24), 2843-2853.