Why do we need to grow organs?
As people live longer, we're going to see increases in organ failure and an increase in the demand for organ donation. The transplant wait list for kidneys reflects that. We are pursuing several different strategies with kidneys — 3-D printing as well as using discarded human donor kidneys and kidneys from pigs as scaffolds to build new organs.
How do you grow a kidney — or any other organ?
If you take a very small piece of the patient's own tissue — less than half the size of a postage stamp — we can get those cells to grow outside of the body. About four weeks later, we can take those cells and apply them to three-dimensional molds in the shape of the organ.
All the body consists of are cells and the glue that holds them together, which is mostly collagen. So the key is to get the cells to grow on a mold created out of a man-made collagen equivalent that becomes a scaffold structure you can put back into the body. It's much like baking a layer cake. You coat the scaffold with the cells, one layer at a time. Then you put it in an ovenlike device that is the same temperature and oxygen level as the body.
What is experimental, and what has been implanted?
Our team is working on over 30 different organs and tissues, including tracheas, bone, cartilage, muscle and ears, as well as the major organs. We have been able to implant flat structures, such as skin; tubular structures, such as urethra channels; and hollow organs, such as the bladder and vagina. We have not been able to implant the complex, solid organs, such as the kidney, lung and heart. Those are considered the holy grail of regenerative medicine.
At what point do you decide it's a go with an engineered organ?
Before we put a new technology in a patient, we will have tested it over and over. Then we ask our team very important questions: "Are you willing to put this in your own child? Your own parent? Your own spouse?" Unless all of us around the table agree that this is something we would put in loved ones, we won't do it.
Talk about genital regeneration for wounded troops.
Genitals, of course, are so central to a sense of manhood, and this is an area of research that has become so meaningful to us. We are working on restructuring the phallus from donor organs reseeded with the patient's own cells that eventually forms a functional phallus, consisting of a circular cylinder holding three rods made of erectile tissue, muscle tissue and the urethra.
We have engineered penile erectile tissue that was functional in rabbits. The new organs had blood vessels and nerves that allowed the rabbits to get erections, mate with females and produce normal, healthy pups.
What ignited your passion for medicine growing up in Peru?
We had a family doctor who made house calls, and I was really impressed that he came to the house. I watched him with his stethoscope when I had a cold, and I really admired that personal touch. I realized early that the end goal of medicine is to make patients' lives better. I always remember the oath we take: First, do no harm. So while we are eager to get these technologies into patients as soon as possible, at the same time we have to make sure when we do so that these technologies are safe.