LONDON – In experimental studies, stem cells have been shown to specifically seek out cancers throughout the body and deliver anti-cancer agents that kill malignant cells but leave normal cells unharmed.

Dr Michael R Loebinger and Dr Sam M. Janes of the Centre for Respiratory Research at University College London, UK, review the current understanding of the potential that lies in the use of stem cells to complement current cancer treatments.

“Recent research suggests that mesenchymal stem cells are able to migrate specifically to tumours and their metastases. This has led to considerable excitement about the possibility of modifying these cells to express anticancer molecules to be used as specific targeted anticancer treatments,” the authors explain in the journal Thorax.

Mesenchymal stem cells, a subgroup of stem cells, are particularly suited to a role as a vector for cancer therapy. With the help of this vehicle, anti-cancer treatment may be directed specifically into malignant tumours.

“This therapy may have clinical application and, although there are many unanswered basic science questions remaining, including the optimal timing of delivery, the number of cells needed, and the mechanism of homing, this has not prevented the development of clinical trials with initial encouraging results and a lack of adverse effects.”

Different anticancer agents delivered by mesenchymal stem cells, such as interferons, chemokines or even viruses, are under investigation as means of reducing tumour growth or metastases.

These mesenchymal cells, however, are not merely vectors for directed cancer therapies, but themselves exert profound immunosuppressive effects, explains Dr Loebinger. Additionally they may have intrinsic antitumour properties as well as anti-inflammatory effects, but they have also been implicated in mechanisms which enhance tumour growth.

Consequently, it remains unclear what effects mesenchymal stem cells have on tumour growth when used as an isolated therapy - the hope seems to lie with mesenchymal stell cells being used as vectors to deliver specific anticancer agents.

“Finally, it is also clear that new modalities of cancer treatments are urgently needed for a desperate disease which may push this research to the clinic,” the authors conclude.

Reference:  Loebinger MR. Thorax. 2010 Apr;65(4):362-9.

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Human embryonic  stem cells
A: Cell colonies that are not yet differentiated.
B: Nerve cell