Carbon monoxide as therapy?

Here’s a result I would not have predicted.  Researchers from Otto-von-Guericke University and from Universitatsmedizin have been exploring the use of carbon monoxide (CO) in the prevention of miscarriage.  Yes, the deadly poison that we’re all warned will kill us if we leave our cars running in our enclosed garages may become the treatment of choice for at risk pregnancies.

CO is actually a natural byproduct of certain enzymes in our body, albeit one that occurs in very low concentrations.  Interestingly, CO appears to play a number of important rolls in the formation and maintenance of the placenta.  For example, there’s an enzyme called heme oxygenase (HO-1) that is required to degrade heme groups (the molecules that, among other functions, carry oxygen around the body).  Although hemes are essential molecules, like with anything, too much of them can be a bad thing.  In this case, excess free heme can interfere with the formation of the placenta, and pregnant females that are deficient in HO-1tend to miscarry.  It turns out that CO can mimic the effects of HO-1. 

Of course, you have to have the right amount of CO. As you increase CO concentrations, more and more hemoglobin is converted to carboxyhemoglobin and becomes useless for delivering oxygen to the body’s tissues.  Pretty soon, you have seizures, coma, and death.

The researchers exposed pregnant mice to CO levels of either 50 ppm (parts per million), the highest amount allowable for humans, or 125 ppm for varying amounts of time.  The good news was that at 125 ppm of CO, the mouse miscarriage rate was lower than for mice breathing room air.  The bad news was that the resulting fetuses were not normal.  At 50 ppm for only a couple of days, the fetuses were normal, but the miscarriage rate was the same as for the room air controls.  Giving the mommy mice 50 ppm of CO for five days turned out to be the sweet spot with fewer miscarriages and normal babies.

So, will pregnant women be given CO spa treatments?  I doubt it.  For one thing, many women don’t even know they are pregnant during the critical placental formation stage.  For another, I’m not sure women would agree to breathe CO while pregnant.  I could be wrong though, and the researchers are interested in designing clinical trials.