The in vivo Relevance of Past Studies Performed in Room Air
A recent paper in Cell (paywalled) from the Broxmeyer group at Indiana University coined the term extraphysiologic shock/stress (EPHOSS) to describe a distinct negative effect of exposure to room air on hematopoietic stem cell (HSC) yields.  In this study, the authors isolated mouse bone marrow HSC with one femur in an atmosphere of constant 3% oxygen and the other in room air. They also took an aliquot of bone marrow cells protected from room air during isolation and exposed it to ambient air during processing for comparison. Learn how in vivo research is affected by room air temperature in our post below.
Their findings were striking.
• ROS production linked to cyclophilin D, p53, and the mitochondrial permeability transition pore (MPTP) dramatically reduced HSC yields when the cells were exposed to room air.
• When murine bone marrow cells were protected from room air at all times, yields were boosted by 5-fold.
• Yields of HSC from human cord blood were increased 3-fold when the cells were protected from room air.
The implications of this work are multiple and profound.
We focus on the first one here:
Past cell work in room air may have severely compromised the applicability of HSC biological, pre-clinical, and clinical studies.
To quote the authors:
“This phenomenon, suggesting that greater numbers of HSCs reside in hematopoietic tissues and that their in vivo metabolism is different from the one ex vivo in air, raises questions regarding the in vivo relevance of studies of HSCs and HPCs collected in air.”
In any scientific endeavor, it is very difficult to look at past work and think about its shortcomings. Ideally, we would like to continuously build on past work, nailing one finding onto the ends of others so as to build a solid scientific platform across gaps in our knowledge.
With increasing attention paid to problems in scientific reproducibility, as in this recent PLOS Biology paper  this is a great time to look back at data gathered from samples exposed to room air and question its utility.
Decades of time, effort, and money have gone into room-air work on HSC and the Cell paper has suggested that most of that work now needs to have a mental asterisk next to it with a footnote:
*All cell handling was performed in room air. The in vivo relevance of these data must be questioned.
We know from basic physiology that room air exposure is fundamentally inconsistent with in vivo conditions. Enclosing all cell isolation and processing in a protected workspace supplied only with medical-grade tanked air can prevent the room air exposure that was detrimental to HSC yields in the Cell study. Their findings could have been predicted from two of the Cytocentric Principles:
Taking the Cytocentric point of view, protection from room air is essential to physiologically relevant HSC and HPC biology.
1. Mantel, C.R., et al., Enhancing Hematopoietic Stem Cell Transplantation Efficacy by Mitigating Oxygen Shock. Cell, 2015.
2. Freedman, L.P., I.M. Cockburn, and T.S. Simcoe, The Economics of Reproducibility in Preclinical Research. PLoS Biol, 2015. 13(6): p. e1002165.
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About The Author
Alicia D Henn, PhD, MBA
Chief Scientific Officer of BioSpherix, Ltd
Alicia Henn has been the Chief Scientific Officer of BioSpherix, Ltd since 2013. Previously, she was a researcher at the Center for Biodefense Immune Modeling in Rochester, NY. Alicia obtained her PhD in molecular pharmacology and cancer therapeutics from Roswell Park Cancer Institute in Buffalo, NY and her MBA from the Simon School at University of Rochester in Rochester, NY.
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