Propagating platelets: a novel cancer therapy?

Every two minutes, someone in the UK is diagnosed with cancer1. There are over 200 forms of the disease, some of which can be diagnosed early and treated easily, and others that form aggressive, destructive growths that destroy the body from the inside out. One common method of treating the disease is chemotherapy, where drugs are used to kill the rapidly dividing cells that cause tumours to grow. On paper, this sounds great – except rarely are these drugs specific to cancer cells alone. They also kill normal, healthy parts of the body – such as the cells in your bone marrow, which are capable of producing millions of blood cells per second2.

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From left to right: red blood cell, platelet, white blood cell (Image credit: Wikipedia)

For patients suffering from cancer, this can be a colossal setback to their treatment. If blood counts fall below acceptable levels, the patient cannot continue with surgery or chemotherapy, leaving them desperately vulnerable to the disease. One specific type of blood cell that are often affected are platelets, which help clot the blood and prevent bleeding. Methods to increase platelet count in patients undergoing chemotherapy could potentially have a huge impact on patient survival and recovery – but to do this, doctors need to know when, where and how these cells are produced.

A recent study from the Nerlov and Jacobsen labs in the Haematopoietic Stem Cell Laboratory and MRC Molecular Haematology Unit at the WIMM has made significant steps towards answering these critical questions3. The tiny population of cells in the bone marrow which constantly replenish your blood are known as blood stem cells, and can be identified by a specific mixture of proteins that sit on the surface of the stem cells. The Nerlov and Jacobsen labs found that 60% of these cells actually produce a protein that would usually be specifically associated with platelets. Careful isolation and analysis of individual cells, which looked like blood stem cells yet also produced this key protein, showed that these cells are in fact a distinct, and previously unknown, population of stem cells particularly primed to produce platelets.

Until this study was published, it was thought that there was just one type of blood stem cell from which all cell types in the blood were produced. The identification of a platelet-biased stem cell population is not only a hugely exciting finding in the field of haematology, but holds significant promise for developing novel therapeutic approaches to stimulate production of platelets in cancer patients as well as other platelet disorders. Cancer may still be a disease that is all too close to home for many people, but findings such as these are the building blocks towards increasingly specific, effective, and safe therapies.

Post written by Bryony Graham.

 

References:

  1. http://www.cancerresearchuk.org
  2. Ogawa, M. Differentiation and proliferation of hematopoietic stem cells. Blood (1993) 81 (11) pg. 2844-2853
  3. Alejandra Sanjuan-Pla, Iain C. Macaulay, Christina T. Jensen, Petter S. Woll, Tiago C. Luis, Adam Mead, Susan Moore, Cintia Carella, Sahoko Matsuoka, Tiphaine Bouriez Jones, Onima Chowdhury, Laura Stenson, Michael Lutteropp, Joanna C. A. Green, Raffaella Facchini, Hanane Boukarabila, Amit Grover, Adriana Gambardella, Supat Thongjuea, Joana Carrelha, Paul Tarrant, Deborah Atkinson, Sally-Ann Clark, Claus Nerlov & Sten Eirik W. Jacobsen. Platelet-based stem cells reside at the apex of the haematopoietic stem-cell hierarchy. Nature (2013) 502 pg. 232-236.