Our Blood Could Be Coming From a Previously Unknown Source, Mouse Study Suggests

Even the most vital and well- studied systems are still throwing up surprises.

A study in mice has shown that blood may have more than one type of cellular origin.

Fernando Camargo is a Harvard University cell biologist and one of the researchers on the mouse study.

A group of progenitor cells that don't come from stem cells were found. Most of the blood is made in fetal life until young adulthood, when it starts to decrease. The cells are referred to as eMPPs.

The cells lining the arteries form the hematopoietic stem cells. Previously, it was thought that eMPPs split from hematopoietic stem cells early in their development.

Hematopoietic stem cells and eMPPs emerged from the same lining using a recently developed genetic bar coding strategy.

The researchers put bits of easy-to- detect DNA into a place within the mouse cell's genome that would be passed on to their descendants.

They were able to trace the origin of all their target cells, revealing that the eMPPs were divided into cells that were responsible for most of the immune cells in mice.

The model below shows how limited hematopoietic stem cells can be in producing immune cells. The cells that make the components needed for blood clotting are produced more often by them.

A new ancestral branch is needed for the family tree. M. Hggstrm is a member of the CC-BY-SA.

We are trying to understand the consequences of the mutations that leads to leukemia by looking at their effects in both blood stem cells and eMPPs in mice. If the leukemias that arise from these different cells of origin are different, we want to know.

The long-standing mystery of why our immune system weakens as we age may be explained by the decline in eMPPs contribution to blood supply.

The team found that eMPP transplants did not last very well in the mice.

If we could add a few genes, they could be a better source for a bone marrow transplant.

They are more common in younger marrow donors than blood stem cells, which could lead to better reconstitution of the immune system and less infections after the transplant.

If the findings are the same in humans, all of this will work. Different mammal species have different pathways for growth and development.

The team hopes to find new ways to boost the immune systems of aging humans.

The research was published in a journal.