With Valentine’s Day not that far behind us, I thought I’d share two fascinating techniques researchers are developing to help patients heal after heart attacks that I could also use to help explain why the characters in the novel I’m writing heal following injury.
It turns out recovering from a heart attack is often harder than surviving one. When blood stops oxygenating the heart, nearly one billion cells die and the heart usually only replaces about 1 percent of its five billion cells in a year. After blood flow is restored, there is a week or two of extra cell regeneration by both adult cells and embedded stem cells, but it doesn’t repair much damage. Scar tissue then forms over the heart and less blood can be pumped from chamber to chamber, sinking patients slowly into heart failure. Yet there are two new therapies that help reduce scar tissue, one involves stem cells, the other gene therapy.
The older of the two therapies is described in the April 2013 issue of Scientific American. Researchers injected heart attack patients with one billion of their own stem cells. While a large number of those cells died, they secreted chemicals encouraging existing cells to divide. Following the treatment, patients found that the average percent of blood pumped from chamber to chamber jumped from 30.3 to 38.5%. Those in the study who were given the traditional treatment for heart attack only improved from 30.1 to 30.2%.
38.5% is not a huge improvement compared to the typical 55-70% range of a healthy person, but perhaps other types of stem cells might yeild better results. Researchers have attempted to use bone marrow stem cells with varied results. One trial gave one group their own stem cells and in another group everyone was given donor cells. Neither group rejected the stem cells and it was even shown that those given stem cells from younger donors reduced scar mass more. If I use stem cells in my novel to explain why characters recover so fully from injury, it will help explain why the younger characters recover more quickly. But before I use stem cells as the explanation for why my characters resurrect, what about a newer treatment that is showing promise in healing broken hearts?
The gene therapy that shows promise for treating heart failure was reported in the February 19 2014 issue of Science Translational Medicine. It involves activating the Cyclin A2 gene in heart cells, which in mammals, is normally silenced after birth. Injecting heart cells with a promoter forced the CCNA2 gene to activate and it lead to cell regeneration and reduced scar tissue. Pigs treated with the gene therapy saw about and 18% increase in the ability to pump blood. Pigs in the control group had a 4% decrease in heart function. Heart cell growth also occurs in petri dishes and in mice subjected to the therapy, and it may soon enter trials on humans. If I use healing genes that turn on when my characters are injured, I will have to do more research about genes associated with growth and regeneration in all the body’s roughly 200 different cell types, but it’s an interesting concept.
At first when I arrived at the concept of characters who “died” and came back to life, I was worried I wouldn’t be able to find an explanation and would have to turn them into vampires to explain their immortality. I’m finding that there are many breakthroughs attempting to fix everything from heart failure to aging. Now my problem is choosing one. Genes that turn on and increase the ability to heal? Or genes that create of stem cells after an injury? Which would you choose?