Sometimes to understand the dramatic effects of spaceflight on living organisms, a picture can tell more than a lot of words about science.
Recently, Liz Blaber and Eduardo Almeida shared the following picture with me from their 2014 publication in Stem Cell Research. The image is a microscopic view of the bone marrow inside the hip bone (femoral head) of mice that flew to the International Space Station. The picture on the left is the ground “control” and the picture on the right is a mouse that was losing bone from being in the microgravity environment in space.
The cells marked in red are red blood cells. The blood cells are increased in numbers, and show increased clustering, but not at a different density. Eduardo and Liz believe that the pores that would normally allow the cells out of the marrow and into the blood have been blocked as part of the bone loss process, and so the red blood cells cannot get out of the marrow. Depending on the fluid shifts and effects on the total plasma volume, the differences could lead to anemia. Investigators looking at the blood of astronauts are also struggling to understand data on blood cell counts and functional immunity using data from the Integrated Immune investigation, and are eagerly awaiting results from the Fluid Shifts Investigation to understand changes in plasma volume. Fluid shifts is a new investigation that began with Scott Kelly and Mikhail Kornienko, and will continue on future crewmembers.
The cells marked in green are megakaryocytes, which are cells that are important in the production of platelets, cells that enable our blood to clot. In this sample, there is only one of these important cells in the image, while in the Earth sample there were three. Liz and Eduardo think that they might have moved out into the circulation due to cardiac deconditioning, but we really don’t know the full mechanism in play.
A few weeks ago, I was asked to speak to a group of scientists and doctors working on new treatments for patients with hemophilia. They were interested in the ways that we integrate different types of data on astronauts to understand the interactions of different systems in their health. Just like hemophilia patients, astronauts are a small group of people that can have very dramatic health effects is the disruption in their bodies affects different physiological systems. There are a wide variety of physiological impacts in hemophilia patients (with problems in the blood clotting proteins in their blood). Of all the things that could go wrong, much of the medical care of hemophilia patients gets focused on presenting small bleeds in their joints which eventually cause permanent damage. The root cause of an illness and the many different effects it can have on our bodies can be surprising. What is amazing to me about the space station is that each time we understand more about the response of a system in the body to microgravity as a stimulus, it also gives us insights that apply to other related needs on Earth. Stem cells and tissue regeneration are disrupted in many ways in space, and that window into physiology gives us the opportunity to make innovative connections in solving health problems on Earth.