Placenta stem cells can be trained to better fight cancers

Stem cells that usually protect the human foetus could be pre-conditioned to enhance their abilities to combat tumours.


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Cells in human placentas can be trained to enhance their anti-cancer properties, according to scientists at KAIMRC.

Mesenchymal stem cells (MSC), found in connective tissue all over the body, modify their phenotype and functional effects on their surrounding cells depending on the microenvironment they are exposed to, differentiating into bone, fat and cartilage cells. Many research groups are investigating their potential to replace damaged or unhealthy tissue. 

A group led by cell biologist, Mohamed Abumaree, from KAIMRC has previously isolated and studied the MSCs in a part of the pregnant uterus lining called decidua parietalis, MSCs (DPMSCs), from the human placenta. They found DPMSCs, which are exposed to inflammation and oxidative stress during pregnancy, enhance the activity of natural killer cells, which play an important role in anti-cancer defences.

Other researchers have, however, found tumours can pump out proteins that undermine the therapeutic properties of MSCs, and some have suggested the cells may help drive the growth of tumors.

In this study, Abumaree and colleagues cultured DPMSCs in the presence of different concentrations of a medium previously used to grow breast cancer cells. They found the cells were able to survive, even when exposed to high concentrations of cancer cell medium, but with reduced ability to proliferate and attach themselves to neighbouring cells.

The researchers concluded this reduced proliferation meant DPMSCs were unlikely to stimulate tumour growth, as other scientists have previously suggested for other types of MSCs.

When the DPMSCs were preconditioned for 72 hours in breast cancer cell medium they regained their ability to interact with and attach themselves to nearby other cells. They were also less able to invade endothelial cells derived from the umbilical, compared to DPMSCs that did not undergo preconditioning. 

“DPMSCs are located at the interface between the mother and the foetus, and have to be durable because, during pregnancy they are exposed to a stressful, oxidative environment,” said Fawaz Abomaray, based at the Karolinska Institute in Stockholm, Sweden, and a member of the research team. “Our study shows that educating them with cancer-conditioned medium in this way could improve their anti-cancer properties.”

The study is believed to be the first to examine how the properties of DPMSCs are affected by exposure to a culture in which cancer cells have previously been grown. 

Abumaree’s team also identified some of the genes likely to be responsible for the effects of the cancer medium on DPMSC properties.


  1. Bahattab, E. Cancer Conditioned Medium Modulates Functional and Phenotypic Properties of Human Decidua Parietalis Mesenchymal Stem/Stromal Cells. Tissue Engineering and Regenerative Medicine 16(6), 615–630 (2019). | article

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