LCFC#17: Keeping heart cells in the heart
Plus: Growing humanized organs in pigs
Hey Lamb Chop Fans,
I want to tell you a little story.
Every time I go to Duke hospital, I give the transplant team a few vials of blood for blood tests. Sometimes the chair I sit in has a direct view of a little metal shelf with a big sign that says something like, Heart Biopsy Samples. I was startled the first time I saw it, knowing that tiny bits of my new ticker would sit on that shelf, waiting to be carted to a pathology lab to test for signs that my body might be rejecting the new organ.
I see that sign less frequently now, only every three months. Yet every time, it gives me pause. It is a subtle reminder of how, for at least a year after transplant, a check-up includes having an incision made in my numbed neck and a long wire with little alligator-like forceps at the tip threaded through a blood vessel into my heart. The catheter goes in, takes a few heart cells, is pulled out, then in and out, for at least three samples.
There’s a moment when the catheter slips deep into the heart and causes extra beats; in my old heart, that was a signal of a possible arrhythmia. Every time this happens with my new heart, I still have say out loud,
“That’s you, right?”
“Yes,” the doctors say. They are patient with me; apparently it’s common for people who have had signal problems in the past to get anxious during this procedure.
Those extra beats disappear as soon as the catheter is removed. But the pre-transplant arrhythmias left a permanent mark on my memory, one that hopefully will fade with time.
An outsider would say, this technique to check for rejection seems invasive, and possibly expensive.
True. And, right now, it is one of the best ways to monitor for rejection and catch it early, raising the success of preventing total organ rejection. A few drawbacks, it takes days to get the results and leaves us, the folks with new organs, anxious that rejection will happen and we won’t know, until it’s too late.
Imagine if doctors had another way to monitor for rejection?
A clever team at Northwestern has been working on it. The team devised a sticky sensor no bigger than a quarter (much smaller than a defibrillator) that monitors the temperature of the transplanted organ, looking for changes associated with rejection. This device could sense a signature temperature change signaling rejection only 8 to 10 hours after it started. And the monitoring is continuous and in real-time; quicker than less invasive blood tests, which are intermittent. As always, there’s work to be done before this is ready for people, mainly because the study was done in rats, specifically monitoring their kidneys.
The line of thought and experimentation give me hope that in the future the anxiety that comes with rejection might be alleviated. That anxiety would be further lifted if we could design an organ from a person’s own cells, which is also in the works by lots of scientists — for one quick take, check out this piece by a colleague on a humanized kidney grown in a pig embryo.
That's all for now, but definitely there's more to come!