Stem cell failures we don't hear (much) about

Stem cell treatment causes nasal growth in woman's back - health - 08 July 2014 - New Scientist

I've always been somewhat skeptical of stem cell therpy, and the enthusiasm with which researchers wanted to mash up embryos to get them.  (I know, the title story of the nose growing on a woman's spine is not involving embryonic cells, but I am still leery of playing around with embryos for any reason.)

So it's interesting to note that there have been spectacular failures in their experimental use, and that we don't seem to ever hear much about them:

There are thought to be more than 1000 ongoing stem cell trials, including two on the US clinical trial register ClinicalTrials.gov, which use olfactory ensheathing cells (see main story, above). However there is an unknown number of people visiting private clinics for unregulated stem cell treatments.

As there is no global register it is unknown how many people have developed additional problems as a result of such therapies, but a few cases have come to light of tumours or excessive tissue growth. One of the first people to receive fetal cells to treat Parkinson's disease was a 50-year-old US citizen in China. Upon his death in 1991, 23 months later, he was found at autopsy to have a teratoma growing in his brain that contained hairs and cartilage (Neurology, doi.org/tjt).


A more highly publicised case was in 2009, when an Israeli teenager developed brain and spinal tumours  after receiving several implants of fetal stem cells in Moscow to treat
a rare degenerative condition. And in 2010, a 46-year-old woman developed multiple tumours in her kidney after having her own bone marrow stem cells injected at a private clinic in an attempt to treat her kidney failure.

There have also been at least three cases of people developing leukaemia after receiving stem cells from umbilical cord blood. However, that is less surprising as ordinary bone marrow
transplants – which are a source of blood stem cells – also carry that risk.

As someone says in the article:

"It is sobering," says George Daley, a stem cell researcher at Harvard Medical School who has helped write guidelines for people considering stem cell treatments. "It speaks directly to how primitive our state of knowledge is about how cells integrate and divide and expand. "

The case shows that even when carried out at mainstream hospitals, experimental stem cell therapies can have unpredictable consequences, says Alexey Bersenev, a stem cell research analyst who blogs at Cell Trials. "We have to realise complications can also happen in a clinical trial," he says.