May 03 - Blood Stem Cells Boost Immunity

A European research team lead by Prof. Michael Sieweke has just made an exciting stem cell breakthrough. They have discovered that blood stem cells don’t just ensure the continuous production of blood cells, they also remember previous infectious encounters, which helps them provide a more rapid immune system response in the future.

This discovery could have a huge impact on vaccination strategies. In could even pave the way for new treatments for individuals who have impaired immune systems or immune system disorders. Details of the study were published in the journal Cell Stem Cell.

Stem cells are powerful cells which have the capacity to create more stem cells or to form specialised cells like skin cells, blood cells, or nerve cells. They are essential for tissue renewal and function.

Different types of stem cells have different properties and capabilities. Hematopoietic Stem Cells (HSC), for example, have the capacity to create blood cells. HSCs are essential maintaining the cells of the immune system which fight infections and diseases.

Until a few years ago, it was thought that HSCs were unspecialised and did not have any capacity to recognise infections. Scientists believed they were solely directed around the body by the lymphatic system. 

However, Prof. Michael Sieweke’s laboratory has proven this belief was wrong. They have shown that HSCs can sense external factors and produce specific subtypes of immune cells on demand. They don’t need to be told by the lymphatic system to increase immune cell production.

It was also discovered that the immune cells had a “memory” which helped them tackle infections they previously encountered. The new study suggests that the body’s blood stem cells have a central role in maintaining these memories.

As Dr. Sandrine Sarrazin explains: “We discovered that HSCs could drive a more rapid and efficient immune response if they had previously been exposed to LPS, a bacterial molecule that mimics infection. The first exposure to LPS causes marks to be deposited on the DNA of the stem cells, right around genes that are important for an immune response. Much like bookmarks, the marks on the DNA ensure that these genes are easily found, accessible and activated for a rapid response if a second infection by a similar agent was to come.”

The finding may help researchers develop new treatments for many conditions including Alzheimer’s disease, Parkinson’s disease, leukaemia, diabetes, and bone diseases.

Source: Blood stem cells boost immunity by keeping a record of previous infections