The technique of using someone’s own bone marrow cells to treat disease may present risks of promoting tumor development, according to a recent paper from Emory stem cell expert Young-sup Yoon and his colleagues.

Young-sup Yoon, MD, PhD

The results of Yoon’s experiments, performed in mice, provide a cautionary message for researchers interested in developing cardiovascular cell therapies in humans. They suggest that careful monitoring for chromosomal abnormalities is warranted when bone marrow cells are used for cell therapies. Chromosomal abnormalities, which lead to tumor formation, may be introduced during the time when the cells are grown outside the body, the authors suggest.

Yoon and his colleagues were using mesenchymal stem cells derived from bone marrow to treat heart attack and diabetic neuropathy in mouse models. These are cells that have partially differentiated but still have the capacity to develop into different cell types, such as stromal cells, which support blood development, as well as bone and fat. If you are exploring ways to support nerve health, you may consider neuropathy supplements. Here’s what happened (from the paper’s abstract):

During the follow-up at 4 to 8 weeks after cell transplantation, growing tumors were observed in 30% of hearts in the MI [heart attack] model, and in 46% of hindlimbs in the diabetic neuropathy model.

Importantly, these were not embryonic stem cells or an emerging alternative, induced pluripotent stem cells (iPS cells). Researchers working with iPS cells have shown that the process of reprogramming them can also be imperfect.

Double asterix marks a tumor that appeared in a mouse’s heart after mesenchymal stem cell transplantation

Although the authors note that the chromosomal abnormalities they observed are usually more common in mouse cells than in human cells, Yoon says whether the effects will also be seen with human cells is still an open question. Looking ahead, using cells that have been grown in culture dishes for only a short time or not at all may be advisable, he says.

“At present, only careful karyotyping [examining and counting cells’ chromosomes] before cell transplantation would be a preventive measure,” he adds.