Low Oxygen Levels May Assist Heart Regeneration

Reducing oxygen concentration in the air from from 21% to 7% triggers heart regrowth in mice

Newborn mammals are relatively adept at regenerating heart damage, but this ability is quickly lost after birth. Some researchers believe one of the reasons for this may be increased oxygen levels, which drive damage and possibly inhibit cellular division and regrowth. 

A team of cardiologists researching the effects of reduced oxygen on heart tissue has now put the theory to the test, lowering oxygen levels in the air to 7% and exposing mice to this concentration (a similar level to the oxygen levels at the top of Mt. Everest). 

"The adult human heart is not capable of any meaningful repair following a heart attack, which is why heart attacks have such a devastating impact. Though counterintuitive, we've shown that severely lowering oxygen exposure can sidestep damage to cells caused by oxygen and turn cell division back on, leading to heart regrowth"

Triggering regrowth

Over a period of weeks the researchers gradually lowered atmospheric oxygen levels from the normal 21% to 7%, allowing the mice to acclimatize to their new environment. While doing so they monitored heart function and mass in these animals and found that overall heart mass increased - caused by cardiomyocyte (heart muscle cells) division which was somehow being initiated by the reduced oxygen levels. Alongside this division, heart function appeared to improve as a whole. 

Curiously, 10% atmospheric concentration had no such therapeutic effect, so the additional 3% reduction made all the difference. It is possible this somehow mirrors oxygen exposure in the womb, and as such activates innate growth pathways that are usually inhibited in adult mammals. More research should discover the exact reason for the regeneration boost, and whether the findings could be applied to humans. While humans can survive in low oxygen, it can have some dangerous side effects and would have to be performed in a controlled environment. 

"This work shows that hypoxia equivalent to the summit of Mt. Everest can actually reverse heart disease, and that is extraordinary. In theory, creating a low-oxygen environment could lead to repair not only of heart muscle, but of other organs as well. Although exposure to this level of hypoxia can result in complications, it is tolerated in humans when performed in a controlled setting"

Read more at MedicalXpress