State of the Union: Kidney Transplantation Today

An interview with Lloyd E. Ratner, MD, Director of Renal and Pancreatic Transplantation.

Kidney transplantation is shaped not only by medicine, but by policy, infrastructure, and equity. As the United States restructures national oversight of organ allocation and as clinical breakthroughs accelerate, questions of access, efficiency, and direction remain central. Dr. Ratner reflects on these changes and what they mean for transplant today and in the future.

Policy, Access, and the Future of Organ Procurement

Three years ago, you said the national goal was to double the number of kidney transplants by 2030. How are we tracking toward that?

It was going well until they started this OPTN [Organ Procurement and Transplantation Network] modernization. It had gone from something like 30,000 transplants a year to about 48,000. But since the government decided to bring in multiple contractors instead of one, they blew up the whole system. No one knows what’s going on, quite frankly.

What does it mean in practice when they restructure it like that?

Historically, there had always been one contract to run the Organ Procurement and Transplant Network, which was UNOS. They decided it would be better to have multiple contractors, so they changed the whole system.

Have these changes improved access?

It certainly hasn’t improved access. I was on the OPTN board–vice president, actually–and was slated to be president. They got rid of the whole board and called a new one. It was a tremendous amount of work. We’re volunteers; they didn’t seem to understand that.

How has this affected organ allocation?

There was a crackdown on out-of-sequence allocation. Not all organs are the same quality. Sometimes you have to go out of sequence, so the organ doesn’t get wasted. If you don’t allow rescue allocation, organs won’t get used—especially marginal ones. They actually tested it in New England. When they stopped out-of-sequence allocation, the organs didn’t get transplanted. It’s real.

So the system made common-sense clinical decisions harder.

Right. Because common sense hadn’t been codified into rules.

Are the national performance metrics for transplant centers improving?

They’re better, but still not great. We now have some pre-transplant metrics, mortality on the waiting list, how many offers a center accepts. But we need to measure every step of the patient journey. There was a consensus conference that created a “subway map” showing those steps, from referral to placement on the list to transplant. You can’t fix what you don’t measure.

Xenotransplantation: A (Still) New Frontier

You mentioned Columbia is working to start clinical xenotransplant trials. How close are we?

We’re trying to get approval. Three companies, and maybe a fourth, have been approved for clinical xenotransplant trials. The trial we’ll be involved in is supposed to start within the year. It’ll be slow. Planned staged enrollment, NYU will do two cases, then we’ll do two cases, and so on.

Would you also pursue compassionate use cases?

We’re trying. A compassionate need case would give us more control over the trial and allow us to adhere closer to the preclinical data.

What have we learned from recent xenotransplant cases?

Two patients at Mass General had functioning xenotransplants. One kidney failed at nine months, which is the longest surviving genetically engineered pig kidney. Every new piece of clinical data matters, because we’ve hit the limits of experimental models. At some point you need to learn from humans.

Organ Preservation and Storage

What’s new in organ preservation?

A lot. Thoracic transplant teams found that if you store organs at 10°C instead of 4°C, they function better. At 4°C, everything shuts down. At 10°C, metabolism slows but repair mechanisms still work.

How was the original temperature chosen?

I don’t know.

Normothermic preservation, or keeping organs at body temperature, has also expanded, right?

Yes. Keeping organs at body temperature with an oxygen supply has been a game-changer for liver transplantation. It allows enzymes to keep working and all the machinery of the organ to keep working. It has really extended the time that a liver could be outside the human body, and so it’s changed all the logistics around liver transplantation.

What about long-term preservation of organs?

People are working on how to freeze organs. Ideally, with xenotransplant, we would like to have organs sitting on a shelf until you need them, rather than having to procure an organ every time you want to do a transplant. That’s not efficient. That’s not great.

Why is freezing difficult?

When organs freeze, ice crystals form within the cells and it damages the cells. So that’s why you can’t freeze things. But you look at some Arctic fish—they’re up there swimming around in the North Pole or Antarctica, and yet they don’t freeze. They have chemicals like natural antifreeze that keep the ice crystals from forming. There are people now utilizing chemicals like that to preserve organs.

Is this work already being applied to xenotransplantation?

Yes. One of my colleagues, Josh Weiner, who’s very interested in xeno, is working on how to freeze genetically engineered pig organs.

How much activity is happening in preservation compared to the past?

There’s probably more going on in the organ preservation space than we’ve seen in the last 30 years. All these things are happening simultaneously, and it’s really exciting times in transplantation.

Breakthrough Therapies and the ‘Boom Phase’

Beyond xenotransplantation, what scientific advances feel most significant right now?

There’s a drug that cleaves antibodies. We’ve used it. If you give it to someone with a highly sensitized immune system, it gets rid of their antibodies. It allows them to be transplanted. It was approved for myasthenia gravis and was given off-label to transplant patients. Now they’re trying to get approval for transplantation.

If that becomes standard, what would it change?

It opens the door for a huge percentage of patients who were previously very difficult to transplant. These are people who’ve had pregnancies, blood transfusions, prior transplants. They’re the hardest group to match. Now they could actually get transplanted.

Do you see these innovations as incremental or transformative?

We’re in a boom phase. You don’t always know you’re in a boom phase when you’re in it, but we are. There are things happening in organ preservation, in antibody therapy, and in xenotransplantation. If you look at it collectively, it’s a wave.

Robotic Kidney Transplantation

Columbia is now performing robotic kidney transplants routinely. What’s the latest?

We’ve done about 16 robotic recipients. It’s still a challenge; we’re getting the whole team up to speed, but it’s a real option for the right patient. The impact will probably be greater for recipients than donors.

What has the learning curve been like?

The younger surgeons are faster on the robot. They grew up with it. I didn’t. I like doing what I’m good at, but you don’t get good unless you do it. And we have to get the whole room good at it, not just the surgeon.

Do patients ever request robotic surgery?

No. Not a single patient has asked for the robot. Most just say, “Whatever you think is best.”

How do you decide who a candidate is?

We mostly do living donor cases, so we can make sure the right team is present. Recipients can’t have bad vascular disease, multiple arteries or veins, extensive abdominal surgery, or pelvic irradiation. The right anatomy and the right timing matter.

How has access to the robot changed?

It used to cost $2.5 million to buy one, so hospitals had to capitalize it. Now it’s pay-per-use. We went from three robots for 60 surgeons to about 11 robots overnight. It changed everything.

The Future of Living Donation

Has the landscape of living donation changed in recent years?

We had close to 2,000 people fill out a donor questionnaire after a celebrity recently died of kidney failure. Five of those people have already come forward to donate to someone else. We call these “residual donors,” people who come forward for someone specific, but who can still donate to anyone.

You’re studying how to engage these donors?

Yes. I work with a colleague in the business school who studies how people make choices. We’re trying to understand what motivates non-directed donation and how to present the choice, so more people say yes.

What motivates someone to donate to a stranger?

Two things: hearing someone’s story and knowing someone who donated. Most donors have thought about it for more than six months. It’s not impulsive. And for many, donating is the most meaningful thing they’ll ever do. It gives them the chance to do something great.

With so many breakthroughs in science and logistics, what’s the biggest opportunity you see ahead?

Giving people the chance to do something great. Why not give everyone an opportunity to be able to do something great and to be great? Greatness isn’t great people doing stuff. It’s ordinary people doing something great that then makes them great.

Do you really think individual donors could meet the need?

In the last 25 years, the number of non-directed donors has increased like 90-fold. If it increased another 90-fold, we’d basically meet the current demand of all the patients currently on the list. It’s genuinely possible.