A kind of stem cell transplant that has long been seen as one of the most promising new kinds of medical treatments could bring a greater risk of cancer than we previously thought. A study has found that more than a fifth of stem cells being grown in laboratories for regenerative medicine research harbour cancer-causing mutations.
The cells tested haven鈥檛 been put into people, but were being used in research to explore their medical use. The findings show that multiplying cells in a dish can cause the dangerous mutations to develop, says at the Hebrew University of Jerusalem. 鈥淭hese are exactly the same mutations you find in human tumours.鈥�
Stem cells that are being studied for regenerative medicine are 鈥減luripotent鈥�, which means they are similar to those in the developing embryo, with the potential to multiply and develop into different kinds of tissues. They are usually obtained either from unneeded embryos made during in vitro fertilisation (IVF) or by taking cells from an adult, for instance skin cells, and administering certain chemical signalling molecules.
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The hope is to find new treatments for a huge range of medical conditions by making these cells develop into specialised kinds of cells 鈥� such as those of the heart, kidneys or eyes 鈥� and then implanting them into the body to replace damaged or diseased organs.
None has yet been approved for routine use, although there are many ongoing clinical trials. Clinics in some countries, such as Mexico and Russia, also offer unregulated treatments, leading to stem cell tourism.
Benvenisty and others have previously shown that stem cells grown in the lab occasionally harbour cancerous mutations. To find out how common they are, the team has re-analysed previous studies that investigated the genes of 146 different collections of stem cells used by various universities around the world.
They found that 22 per cent of the samples had at least one mutation in a gene that can cause cancer when it is mutated in people. One of the most commonly affected was the p53 gene, mutations in which are behind many human tumours.
Once mutations arise that let cells multiply faster, the mutated cells may outcompete other cells and take over the dish, although they probably need several mutations to become a tumour, says Benvenisty.
The findings don鈥檛 mean these stem cells can鈥檛 be used as therapies, but it shows researchers need to take steps to make sure they don鈥檛 transplant cancerous cells into someone鈥檚 body, he says.
As a precaution, Benvenisty says researchers should keep cells in a dish for as short a time as possible, as each cell division gives a chance for new mutations to arise.
In 2022, doctors at Yunnan Cancer Hospital in China reported how one person developed an aggressive form of cancer .
And in 2016, a man he received at clinics in Mexico, Argentina and China. Two years earlier, a woman had a non-cancerous growth removed from her spine that started from an implant of stem cells taken from inside her nose during an approved clinical trial in Portugal.
at the University of Sheffield in the UK says researchers need to agree on standardised ways of checking these stem cell treatments for dangerous mutations. 鈥淥bviously this is a concern, but we still want to ensure that cell therapies progress to the clinic,鈥� she says.
Nature Biotechnology
