Blood in the Lungs – It might not be as bad as you think

Although having blood in the lungs is the worst (well it’s up there), this new discovery about blood production in the lungs is fascinating!

Researchers from the University of California, San Francisco (UCSF) and the University of Los Angeles (UCLA) collaborated and have recently revealed research that shows that the lungs actually participate in blood production in mice.

More specifically, the team found that in mice, the lungs created over 50% of the platelets in the mouse’s blood. Platelets are cells that play the essential role of clotting up the blood in order to stop the bleeding from an injury. In addition to this, the researchers also located a group of blood stem cells which can participate in blood production while the stem cells in the bone marrow are recovering. This also means that the stem cells in the bone marrow may not be the primary source of blood as it had been thought of as before.

These discoveries came about when the team was studying the workings of the immune systems and looking at the platelets in the lungs. They engineered a mouse strain that would glow green fluorescent light and decided to open an investigation when they observed the large amount of megakaryocytes, which are cells that make platelets, in the lungs.

Visualization of resident megakaryocytes in the lungs. Image credit: Emma Lefrançais et al, doi: 10.1038/nature21706.
“Visualization of resident megakaryocytes in the lungs.” Photo from Emma Lefrançais et al

The photo above are the air sacs called the alveoli. The red dots are the megakaryocytes. The investigation showed that the megakaryocytes were active and well in the process of making over 10 million platelets per hour! Using video microscopy, they also uncovered an estimated 1 million cells that were precursors to the megakaryocyte cells and blood stem cells that were sitting just outside of the lungs.

Watch this amazing video by UCSF to get a better picture of what is happening in the lungs!

Having found this, a new inquiry was proposed: the team wanted to learn more about the passage of the cells between the lungs and the bone marrow. In order to find out more, they decided to perform a lung transplant study consisting of a couple sets of experiments.

  1. They started by transporting normal lungs from mice that did not have the fluorescent megakaryocytes into mice that did have the glowing cells in their bodies. They quickly observed that the glowing megakaryocytes appeared in the normal mice lungs. This shows that the platelet-producing cells may be coming from the bone marrow.
  2. The second transplant experiment involved moving lungs with fluorescent cells into mice that had a low amount of existing platelets and the results did not disappoint. With the introduction of the lungs, there was a significant spike in the amount of glowing platelets now being produced in the mouse. Enough were created so that the platelet levels were returned back to normal. This outcome continued for months, outlasting the life of a single platelet or megakaryocytes.
  1. In the last experiment, they transplanted healthy lungs containing all glowing cells into mice with bone marrow that had an ineffective amount of normal blood stem cells. The cells from the lungs were able to restore platelet levels but also aid in creating other types of blood cells like neutrophils, a type of white blood cell.
Screen Shot 2017-04-14 at 12.48.56 AM
Experiment 1, don’t mind my digital drawing skills. This is just to help visualize.
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Experiment 2 and 3 basic visualization

UCSF Professor Mark R. Looney believes that the team’s observations of blood production being connected to the lungs suggest that the lungs also play a significant part in blood production in human bodies. Furthermore, Professor Looney states that “To our knowledge this is the first description of blood progenitors resident in the lung, and it raises a lot of questions with clinical relevance for the millions of people who suffer from thrombocytopenia.”

What do I think?

I enjoy reading the experiments because it seems adorable and it is one that benefits mice to some extent. Can you imagine the mice getting healthier? I also did a little digging and found out that the research team has a special mice surgeon (not the actual title). Imagine operating on such a tiny creature!

This article has shown me a pretty fun approach to experimenting or I am just excited like that. I cannot explain why I particularly enjoy the fact that the experiment is done in three parts with different variables being changed and each having an interesting result. I also cannot imagine how exciting it was to gain these lab results! There just seemed to be one exciting development after the next. I am super happy for the success of this project!

I believe that I have read and written about a few articles on this blog that have to do with some form of microscopy and I find phosphorescence or fluorescence to be such a simple yet innovative way to track the movement of a specific cell within a body. I think I could spend a lot of time just looking at the movement of the glowing cells and photographing the progress. Additionally, I just learned that you can engineer a cell to be fluorescent. In the article, they used “a mouse strain engineered so that platelets emit bright green fluorescence.” I do not know if this is only visible under a special camera but what if we engineered a human strain (I am not sure if that would mean a gene or a protein or a stem cell etc.) that makes us glow in the dark. We could save a lot more electricity and it would be easier to walk around at night but it might be inconvenient if we are trying to sleep and we are glowing. I also do not know how they would implement this.

Moreover, I like how this article shows a new discovery about what goes on in bodies albeit mice ones at that. I think that nature always finds a way to restore things and have a balance and it does so pretty efficiently without human interference. Our bodies and what happens inside is an example of that and so it does not seem super insane that our lungs might be connected to the circulatory system in this way also.

My brainstorm/ What I think are potential applications:

I found this article and the research extremely interesting and exciting because of all of the potential applications of this research in the healthcare field. Even though they only mention how this might be helpful towards sufferers of thrombocytopenia (having low levels of platelets), it can be much broader than that. For example, the blood disorder hemophilia is when the body is unable to form blood clots and platelets are responsible for making blood clots although I am not sure if hemophilia is specifically due to a lack of platelets or some other component. I have not met anybody that has hemophilia, but from watching televisions shows and reading the textbook in biology class, I know that hemophilia is very dangerous because it can cause extreme blood loss and internal bleeding that may not even be detected until it has done too much damage. The parents of children who have hemophilia have to be extremely cautious that their child does not fall down on the playground. I think that if anything does come out of this research, it would definitely be able to help many people to live their lives a little more comfortably. (Side note: I am not sure if hemophilia is the same, a type of or related to thrombocytopenia).

Leukemia, which is one of the cancers affecting white blood cells is another blood disorder that comes to mind when speaking of this subject. Red and white blood cells are created by the stem cells in the bone marrow but as we saw from this article, in mice, there are stem cells available in the lungs that actually support the production of other blood components. If this is the same in humans, this means that it could be a potential new source of stem cells for blood. The stem cells found around the mice lungs were not new but the location that they were found in was a new discovery. Now that it has been linked to blood production and the lungs, what is the future of these cells? Obviously, I have nary a clue as to how stem cells are transferred but if doctors or scientists were able to extract any stem cells from donated lungs that are expiring and put them to good use, then there would be less wastage. Furthermore, there is always engineering that can be done, especially with a stem cell since it already has a lot of potential.

Although it would be disappointing if the lungs did not play similar roles in humans as they do in mice, I think this still raises an interesting question for mice enthusiasts: how come mice can do this but we cannot? What other bizarre connections are we going to find out about in the near future? Are my knees connected to my hearing? And not that I am encouraging for scientists to do this with other animals unless it helps more than it harms, but is this also present in other animals? If it did happen, I think that would greatly increase the chances that we can produce blood components in the lungs.

Anyway, I would be excited if there are any new developments to this experiments. Especially those related to the human part of this but lung transplant experiments are much tougher to carry out with humans.

Something else for the mice enthusiasts. This is footage of the mice after the fluorescent cell containing lung transplant. (Just kidding. This is a cheese commercial! Don’t worry, it’s not sad.)

Read the article I did here ->

If you are intrigued by the group of scientists who worked on this, here is a link to their website Looney Lab. They seem like a fun group of people! –>

Reference list:

Lungs play previously unknown role in blood production. Sci News [Internet]. 2017 [cited 31 Mar 2017]. Availible from:



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