About the research

UNOS conducted an online survey to assess the public’s attitude toward xenotransplantation to measure public support and identify personal characteristics associated with acceptance. Over 1,400 adults participated between April 8 – July 8, 2024. People belonging to religious and racial minority groups were intentionally included in higher numbers so the results would more appropriately reflect the U.S. population.

UNOS received grant funding from Sanofi to conduct research about xenotransplantation. UNOS continues to conduct research on xenotransplantation as part of its mission.

What is porcine xenotransplantation?

Transplanting genetically modified pig organs into humans.

Key findings

Nearly 9/10 respondents support porcine xenotransplantation

Support varies by race, religion, political affiliation, and a person’s experience with transplantation

Black and Muslim respondents were less supportive of xenotransplantation compared to other groups

Over 60% shared concerns of patient safety or animal-derived disease transmission

Support for Xenotransplantation

Support using porcine organs

Would accept for self with similar risks and benefits

Would accept for loved one with similar risks and benefits

Why this matters

Xenotransplantation could shorten the waitlist by making more organs available for transplant. Understanding the public’s beliefs and concerns will help guide how the transplant community and the public are educated on xenotransplantation to ensure everyone has access to clear, accurate information.

What’s next

UNOS is assessing providers’ and transplant administrators’ attitudes towards xenotransplantation.

About UNOS research

UNOS conducts research as part of its mission to save and transform lives through research, innovation and collaboration.

The Centers for Medicare & Medicaid Services (CMS) recently released proposed changes to the Increasing Organ Transplant Access (IOTA) Model, which aims to increase kidney transplants nationwide. A key element of the proposal focuses on improving transparency for patients on the transplant waitlist by requiring participating hospitals to provide regular, individualized reports to patients detailing information about their waitlist status and the organ offer decisions made on their behalf.

There is no question: Ensuring patients are informed about their waitlist status and organ offer information is critical. But how this information is communicated to patients matters as much as the information itself. Complex medical details and interactions with transplant teams can become overwhelming, and physicians play an essential role in translating that complexity by helping patients and their families understand their treatment.

UNOS supports CMS’ efforts to make sure patients receive timely updates about decisions made by their care team that could affect their chances of receiving an organ — but sharing raw clinical data alone isn’t enough. True transparency means presenting information in a clear, consistent format, and in a way that does not add administrative burden to hospitals.

To achieve this balance, CMS should work with the Organ Procurement and Transplantation Network (OPTN) and its contractors to securely transmit patient attribution lists to the OPTN, which would allow for:

• Automatic creation of the specific reports required for each Medicare patient;
• Easy‑to‑read, consistent formatting that patients can understand; and
• Reduced burden on hospitals.

To make this information even more accessible to patients, CMS could also:

• Send the reports directly to each Medicare patient after receiving them from the OPTN; or
• Work with HRSA to hire a contractor to build a secure online portal or app where transplant patients can view these reports and educational materials.

The proposed updates to the IOTA model could enhance the patient experience by empowering them to participate more actively in their care and reduce the stress and anxiety that come with awaiting a lifesaving organ transplant. That said, the information must be presented in a way that patients can understand, and hospitals must be able to implement the IOTA requirements without a disproportionate burden.

UNOS has already begun work to support the successful implementation of CMS’ IOTA Model by developing a dashboard for transplant hospitals that helps them track the IOTA performance metrics and is ready to work with CMS and the community to develop additional tools for participants and patients.

Read UNOS’ public comment on the proposed updates to the IOTA model below.

UNOS Comment on Proposed CMS IOTA Model Updates

At the University of Pittsburgh Medical Center (UPMC), the UNOS Transplant Benchmark Report has become an indispensable tool. Yawah Nicholson, director of Transplant Quality and Performance Excellence, says her team relies on the Benchmark Report “for every single one of our discussions and quality improvement meetings.”

With the latest updates to the Benchmark Report, programs like UPMC can quickly compare their performance to previous years, national benchmarks and other transplant centers, making it easier to make data-driven decisions, track performance and identify opportunities for improvement.

Nicholson says the ability “to really play around with” customizable comparisons helps UPMC understand how it measures up to both peer institutions and to higher-volume transplant programs.

“And being able to do it in real-time during quality meetings has been really nice,” she says.

Before UNOS’ Benchmark Report was available, UPMC staff spent significant time searching external sources for data. “I was doing all this research on PubMed,” Nicholson says. “Without the Benchmark Report, we would be wasting so much time digging for data.”

With immediate access to timely waitlist and transplant metrics, Nicholson can now easily answer questions during meetings, providing immediate data-driven insights. She can also use the Benchmark tool to generate charts and graphs, making it easy to visualize trends—no more poring over spreadsheets.

This data accessibility is a major advantage for transplant centers of all sizes, especially smaller programs that lack dedicated analysts.

Nicholson is also a big fan of the report’s estimated creation time feature, calling it “chef’s kiss.”

The UNOS Transplant Benchmark Report helps clinical leaders like Nicholson work with more agility, clarity and confidence. Having real-time access to high-quality data at her fingertips “has been a really cool change,” she says, giving UPMC the insight it needs to improve outcomes, plan resources and expand access to lifesaving transplant care.

Explore the UNOS Transplant Benchmark Report

While the federal government shutdown has paused some of UNOS’ functions as a contractor for the Health Resources and Services Administration (HRSA) to support operations of the Organ Procurement and Transplantation Network (OPTN), it has not affected the rest of our portfolio of work. UNOS continues to provide professional services, develop technology solutions and support clients without disruption.

A significant portion of UNOS’ workforce is dedicated to supporting our clients with products and solutions ranging from data analytics and research to predictive modeling and data visualization tools, among many others.

For the past month, we have been rolling out upgrades to our suite of UNOS tools for transplant hospitals. These upgrades make their work faster and more efficient, and enable more informed decision-making.

UNOS continues to provide professional services, develop technology solutions and support clients without disruption.

Planning for our 2026 Transplant Management Forum (TMF) conference in Atlanta continues uninterrupted, and we are excited to once again host the largest annual event focused on collaboration between transplant administrators, clinical and financial coordinators, social workers, OPO executive directors, physicians, surgeons and industry allies. This year’s TMF theme is “Transplantation for Tomorrow: Where Innovation Meets Action,” with an agenda focused on how changes in system structure, policy and emerging technologies can be channeled into positive impacts on donation and transplantation. There are still opportunities to sponsor and participate at TMF at a variety of levels. For more information, contact Devin Holland at [email protected].

Despite ongoing challenges due to the federal government shutdown in our work with the federal government to support OPTN operations as part of our contract with HRSA, UNOS’ broader operations remain intact, and our workforce remains committed and strong. As UNOS continues urging lawmakers to quickly settle on a funding solution to reopen the government, we are ready and able to continue working with new and existing partners to advance the field of organ transplantation and improve patient outcomes.

Despite what you may have heard or seen in pop culture, waiting for an organ transplant is not like taking a number and waiting for your turn. People often refer to “the waitlist” to describe how the system works, but the reality of how it all works, and who is involved in the process, is significantly more complicated.

The United Network for Organ Sharing (UNOS), in its role as a federal contractor, helps pair donated organs with patients in need.

Is it really a list?

To better understand how patients are matched with lifesaving organs, it’s helpful to think of the people in need of an organ transplant as being grouped into a “pool” of patients. Patients get added to the “pool” by transplant teams at the patient’s transplant hospital. Those teams evaluate patients and make the final decision on whether or not an organ transplant is the proper treatment. Each time an organ becomes available, UNet – UNOS’ organ matching technology – searches the entire pool for the patients who are a match for the organ based on factors such as blood type, immune system characteristics, organ size and health status. Medical urgency and time spent actively waiting for an organ are also considered. This means every time an organ is available for a transplant, the system creates a new prioritized list, known as a “match run,” from the people in the pool, in the order determined by Organ Procurement and Transplantation Network (OPTN) policy.

Who decides how organs are offered to patients?

When an organ becomes available for transplant and an offer is made to a patient in need, the decision to accept or decline the offer is made by the patients’ transplant team who care for them at their transplant hospital. How organs are allocated is determined by policy, built by independent, volunteer committees made up of donation and transplant professionals, doctors, patient and donor families and members of the public. Those committees are established by the OPTN to write policy and improve the national system. Once a match run is created, organ procurement organizations, or OPOs, use UNet to send offers to patient transplant teams in the order prescribed by OPTN policy. Important decisions about patients, such as accepting an offered organ for a patient, are made by the transplant doctors and teams at transplant hospitals across the country.

What does UNOS do?

As part of its OPTN contract with the federal government, UNOS created and maintains a secure web-based application to collect relevant information about transplant candidates and donors, creates matching algorithms that execute OPTN policies, and connects OPOs with transplant teams. UNOS, under its federal contract, also maintains databases of post-transplant information about patients and living donors to help monitor patients’ health following their transplant. These data can provide feedback to transplant hospitals and OPOs and help the OPTN monitor how policy is working, improve patient safety and write future policy changes.

Let’s take a closer look at how donation and transplant work, and the role UNOS plays in it.

How does this process work?

UNOS is responsible for the work designated in its OPTN contract, which is determined by the Health Resources and Services Administration (HRSA), in accordance with the National Organ Transplant Act, OPTN Final Rule and all OPTN policies. That work, which includes building and maintaining the software that connects a lifesaving organ donation from a generous donor to a potential recipient, is just one piece of the complex network that saves lives through organ donation and transplant every day. UNOS is dedicated to helping people live life without limits by helping people get the lifesaving transplant they need.

Read more about the ways UNOS aims to save and transform lives through research, innovation and collaboration.

The U.S. organ donation system is complicated — doctors, hospitals, OPOs, labs and multiple federal agencies all play a role. When safety concerns arise, figuring out where to report them shouldn’t be confusing.

The U.S. organ donation and transplant system is a complex network of doctors, hospitals, organ procurement organizations (OPOs) and histocompatibility labs, operating under policies and regulations managed primarily by three entities: Centers for Medicare and Medicaid Services (CMS ), Health Resources and Services Administration (HRSA) and the Organ Procurement and Transplantation Network (OPTN). Navigating this system can be challenging for patients and families, especially when there’s the compounded stressful urgency of a patient safety concern.

That’s why UNOS is advocating for a “No Wrong Door” comprehensive patient safety reporting system. The idea is simple: Anyone — whether that’s a patient, physician, nurse, family member or friend — should be able to report safety concerns easily, effectively and anonymously, without needing to know what agency is in charge or who to talk to when an issue arises.

In July, UNOS CEO Maureen McBride called on Congress to direct HRSA and CMS to work together to create a No Wrong Door reporting system. If someone experiences poor care or witnesses a problem related to organ donation or transplant, they shouldn’t have to navigate a maze of agencies to speak up, be heard and get a resolution. A No Wrong Door system would serve as a central reporting hub and route reports to the correct regulatory authority.

Currently, people can report concerns and allegations of misconduct anonymously by email at [email protected]. There is also a secure online portal and OPTN Member Reporting Phone Line available to OPTN members (OPOs, transplant hospitals and histocompatibility labs) who are required to report certain events in accordance with OPTN policy, and many also submit voluntary reports. However, anyone who is not an OPTN member, such as a donor, family member or a patient, would have to do research to find options for reporting.

For this system to work, a No Wrong Door reporting system must be well-publicized and easy for the American public to understand. It must route all safety concerns to the correct authority, regardless of where the incident occurred or where it got reported. The system must protect the anonymity of individuals who make a report. It should also track and publicly report outcomes of safety investigations to strengthen trust and accountability.

A No Wrong Door reporting system would help preserve and strengthen trust and ensure that organ donation and transplantation in the U.S. remains fair, effective and safe. Patients, families and other stakeholders deserve a reporting process that’s accessible and does not require them to understand the transplant and donation system’s complex governance structure.

What could a No Wrong Door system look like?

1. The system should have ONE entry point. No matter who you are or what role you play in the organ donation and transplantation community, all submissions should go through a central hub.
2. There should be multiple ways to access the entry point. Even though there should be only one intake point, contact information should be published everywhere it’s likely a person in the community may try to find it. For example, the same information should be on the HHS website, the HRSA website, the CMS website and the OPTN website.
3. One team should triage the reports. This team should be highly skilled and highly collaborative. It should evaluate each claim to determine how it should be investigated, and whether CMS, HRSA or the OPTN is responsible. If multiple entities need to investigate, the investigations should be collaborative, and information should be shared amongst the entities.
4. There should be public reporting about the outcome of an investigation. The high-level outcome of a complaint should be reported by the relevant organizations, and a report or dashboard of such outcomes should be on their websites and updated regularly.

Another promising medical trial that could save lives thanks to genetically modified pigs: The FDA has given a select group of companies permission to use modified pig livers as a dialysis-like treatment for people with liver failure.

The process would involve circulating a patient’s blood through the pig liver to help clean the blood of contaminants, excess fluids and waste products to improve or stabilize the health of a patient. The clinical trial would include up to 20 patients who don’t qualify for a liver transplant.

UNOS Chief Medical Officer and former liver transplant surgeon Dr. Andrew Klein says this new advancement is based on a treatment that was first used in the 1970s called xenoperfusion. He spoke recently about what this new FDA trial could mean for saving lives.

How does this compare to a kidney dialysis machine?

Dr. Klein: One of the things that distinguishes a liver transplant from a kidney transplant, which happens more frequently, is in most cases with kidney failure, there are other therapies which can take over the kidney’s function for a period of time, such as dialysis. You don’t really have anything that could take over liver function aside from a new liver. That’s what this new development is trying to become, a sort of dialysis function for people experiencing liver failure.

Do you have experience with xenoperfusion?

Dr. Klein: In 1993 or 1994, I had a patient at John’s Hopkins, a woman who had acute liver failure, was comatose, and was listed as a candidate for a liver transplant. We didn’t have an organ available, but I had a young surgeon working with me who recalled xenoperfusion from the 1970’s as a viable potential treatment for this patient.

So, we got in touch with a farm that housed pigs in an appropriate way for research and went through a whole process. We got consent, procured a liver from the pig, brought it up to the ICU and started the process of perfusing the patient’s blood through the pig liver and then returning it to the patient.

Within 20 minutes, the patient woke up out of her coma and she improved clinically for a number of hours. Eventually the pig liver deteriorated but the good news is we got extra time to find a liver transplant for her. She was transplanted with a donated (human) liver, and she survived and went home.

So, this treatment is not entirely new, but what probably makes it novel and perhaps more durable is the fact that they’re using genetically modified pigs.

How could this be applied to patients today?

Dr. Klein: Two applications come to mind immediately. It could serve as a bridge to transplant, buying a patient time while transplant teams wait for a viable donated organ to become available. It could also be used as a standalone treatment that makes transplantation not necessary, giving the patient’s liver time to regenerate a certain amount and resume functions.

The companies running the FDA trial will need to determine what functions will be restored by this dialysis, will the treatment act as a liver cleanse, removing the body of toxins and waste products, and/or will it restore synthetic functions, such as resupplying the body with substances livers normally produce? I am really intrigued by this second potential application; it could be something that saves someone from being on the transplant waitlist entirely.

Positive results from this FDA trial could mean another step towards saving the lives of patients experiencing organ failure. Read how UNOS is building technology to connect patients with lifesaving organs and how else doctors are using genetically modified animals to save lives.

As more than 100,000 people await transplant, Donation after Circulatory Death (DCD) plays a significant role in our nation’s donation and transplant system. Last year, more than 7,200 DCD donors made up 43 percent of all deceased donors.

DCD refers to the recovery of organs from a patient who has died due to the irreversible loss of circulatory and respiratory function — when the heart has stopped beating and cannot be restarted. This is distinct from Donation after Brain Death (DBD), where death is declared based on irreversible loss of brain function. Both definitions of death are recognized under the Uniform Determination of Death Act (UDDA), which has guided state laws for over 40 years.

Typically, DCD is an option after a patient has suffered a catastrophic neurologic injury but does not meet the medical criteria for brain death.

The first step in the DCD process is the determination by the patient’s doctor that continued life-sustaining support of circulatory and lung function for this patient is futile, is not in the patient’s best interest, and that it should be withdrawn. If the patient’s doctor makes that determination according to their medical training and judgement, the doctor discusses withdrawing life-sustaining care with the patient’s legal next of kin.

It is important to note that individuals from the organ procurement organization (OPO), the organ recovery team, and the transplant team may not participate in the discussions or the decisions to withdraw life-sustaining care from a patient. Only after the next of kin has consented to withdraw care may members of the OPO enter into discussions with the next of kin to consider the option of organ donation if the patient dies after care is withdrawn.

If the next of kin want to pursue the option of organ donation, they must give consent to do so. The decision to withdraw care must occur before any discussions about consent to donate organs.

If the next of kin decide to withdraw care, the patient is typically moved to an operating room by the hospital nursing staff, where the patient’s doctor directs the hospital nursing staff to disconnect the patient from artificial ventilatory support. As the patient’s blood pressure and blood oxygenation levels fall, different organs will tolerate different periods of oxygen deprivation. After a patient’s heart has stopped beating, the treating physician makes the determination that the patient has suffered circulatory death. Circulatory death determination varies between states and hospitals but generally there is a requirement for 2-5 minutes of sustained cessation of heartbeat before a person is declared dead. Declaration of death is made solely by the treating physician. Only after death is declared, the OPO and organ recovery team may enter the operating room. At that point, organ recovery begins.

Many transplant centers have adopted a defined acceptable time limit between withdrawal of care and cessation of heartbeat (cardiac asystole) for donated organs to be acceptable for transplantation. If this limit is exceeded, the patient will not be eligible for organ donation. In 30-40% of potential DCD cases, organ donation is cancelled for this reason.

The United Network for Organ Sharing (UNOS) has long served as a federal contractor for the U.S. Health Resources and Services Administration to support the national Organ Procurement and Transplantation Network; however, UNOS has no involvement in death declaration, nor does UNOS create policy or law related to death declaration. UNOS is not a healthcare provider, and as such, does not make any clinical decisions related to patient care or organ donation. UNOS does not provide clinical care, participate in decisions to withdraw life-sustaining treatment or regulate hospitals.

UNOS remains steadfast in its support of improving outcomes for patients and increasing safe access to life-saving organ transplants with our proposed reforms that would strengthen many aspects of the organ donation and transplantation ecosystem both within and outside the purview of the Organ Procurement and Transplantation Network. To read more about these reforms please visit our advocacy agenda and our action agenda.

Andrew Klein is Chief Medical Officer for the United Network for Organ Sharing. He received a bachelor’s degree from Duke University, an M.D. and an MBA from Johns Hopkins University.

Hospitals throughout the United States play vital roles in saving and enhancing lives through organ donation and transplantation. But an individual hospital’s responsibilities can differ, depending on whether it is a donor hospital or a transplant hospital.

Donor hospitals

More than 5,000 hospitals in the United States have the potential to admit and care for people who may become organ donors. These range from small, rural community hospitals to major metro trauma centers – any facility with intensive or advanced acute care capabilities. Potential organ donors may meet medical criteria for donation either via brain death (complete, irreversible loss of brain function) or donation after circulatory death (DCD), occurring and pronounced in a hospital setting.

Donor hospitals are responsible for declaring patient death according to applicable state law and accepted medical practice. In addition, all donor hospitals must comply with state and federal laws and regulations regarding identification and referral of potential organ donors to their assigned organ procurement organization (OPO). In general, donor hospitals are overseen by the Centers for Medicare & Medicaid Services (CMS). CMS provides regulations, including conditions of participation, that apply to all hospitals seeking Medicare reimbursement.

Donor hospitals are not members of the national Organ Procurement and Transplantation Network (OPTN) and are not subject to OPTN policies and requirements unless they are also a transplant hospital. The national OPTN, overseen by the federal Health Resources and Services Administration (HRSA), does not have policies governing donor hospitals. The OPO managing the logistics of the donation process is, however, accountable to CMS requirements and to OPTN policies and bylaws.

Transplant hospitals

There are 251 hospitals in the United States accredited to perform transplants of at least one organ type. Each of these hospitals is accountable to state and federal standards for quality of patient care and ensuring patient safety. CMS has a number of applicable regulations and conditions of participation that apply specifically to transplant hospitals.

Each transplant hospital must also be a member of the OPTN and must abide by the OPTN policies and bylaws that govern the transplant process and standards for ensuring patient safety.

Can a donor hospital also be a transplant hospital?

Yes, an individual institution can be both a donor and a transplant hospital. As a transplant hospital, it must be an OPTN member and meet the standards the OPTN establishes. But if it is functioning in its donor hospital capacity, there are no additional OPTN standards or requirements that would apply to it.

The majority of donor hospitals in the United States are not OPTN members and would not be compelled to become OPTN members by any law or regulation. However, they remain responsible for all other state or federal requirements that apply to any part of the donation process.

Many people avoid checking their luggage to avoid potential loss and delays. So why does the U.S. ship lifesaving, donated organs for transplant in cargo?

The federal government confirmed that current federal regulations do not prohibit unaccompanied organs from flying above the wing. However, the government agreed it could improve its communications to airlines and airports to clarify this. UNOS appreciates this important clarification.

Before the attacks on September 11, 2001, donor organs were transported in the cabin of commercial flights under the watchful eye of the flight crew before being delivered directly to transplant professionals.

The attacks prompted protocol changes at airports, and since then, organs have been transported with cargo. Today’s misunderstandings of the rules have prevented unaccompanied organs flying in the cabin, so precious organs are moved across the country in the cargo hold.

Transporting organs as cargo is a fundamentally bad practice.

It requires more logistical planning and does not lend itself to the time-sensitive nature of organ transplantation, where every second counts. Donor organs must be transplanted within a specific and limited period of time to patients in need 365 days a year.

Organs transported by cargo must arrive at the airport 60 to 120 minutes before a flight departure. If an organ arrives after the cut-off time, it cannot be transported on that flight. Also, airline cargo offices have highly variable hours, and if an organ arrives at its destination on time but the cargo office is closed, it cannot be collected by a courier.

Logistical delays heighten the risk that a viable organ cannot be transplanted. According to the nation’s Organ Procurement and Transplantation Network, 2.5% of unused organs are due to transportation issues.

For all of these reasons, UNOS is working to ensure organs can be transported in the cabin of airplanes.

As a result of UNOS-led advocacy, Congress demanded the U.S. Department of Transportation and the Federal Aviation Administration convene a working group to fix this issue. That group published recommendations in May 2025.

Here’s the bottom line

Lifesaving organs should not be relegated to airplane cargo bays, where they are more prone to be lost or delayed because of cargo staffing limitations. Transporting lifesaving organs in airplane cabins ensures that they will be handled with care and avoid damage, delay or loss, which will help more people get the transplant they need.

UNOS looks forward to the airlines’ and federal government’s implementation of the FAA Organ Transportation Working Group recommendations to once again transport organs in the most efficient and responsible manner: in the aircraft cabin. While it’s the responsibility of organ procurement organizations – not UNOS – to transport organs, UNOS is committed to making this change to improve patient outcomes and ensure all organs can be transported and transplanted quickly and safely.

Data is powerful

With analysis, data can reveal trends and lead to a greater understanding of what factors may cause a certain health condition or what could provide a potential treatment. At UNOS, our analytics and research team use organ donation and transplant data to determine key trends and identify ways the system could more efficiently help people get a lifesaving transplant.

We deliver these insights to donation and transplant professionals to help improve patient outcomes and enhance performance improvement initiatives.

To access this information, UNOS submits data requests to the Organ Procurement and Transplantation Network (OPTN), which has data on transplant recipients, candidates and organ donors.

How do data requests work?

Any individual or OPTN member can submit a data request by filling out the form on the OPTN website. Different datasets are available depending on the requester’s needs. Once the data request is filed, the contractor supporting the OPTN will reach out to ask any questions and coordinate delivery and payment, as well as proper approvals from the government, when applicable.

Even as an OPTN contractor, UNOS follows the same steps as everyone else to request data for our industry leading transplant research and data analytic tools. Click below to read more about how UNOS tools can help donation and transplant professionals analyze and understand OPTN data better to enhance their work.

Read more about UNOS tools

UNOS Chief Medical Officer Dr. Andrew Klein wrote an opinion piece sharing his first-hand experiences as a liver transplant surgeon and his thoughts about how Congress could help address some of the challenges he encountered. Dr. Klein served as the founding director of the Johns Hopkins Comprehensive Transplant Center and the Cedars-Sinai Comprehensive Transplant Center.

Below is the beginning of Dr. Klein’s opinion article. The full article is published in Nephrology News and Issues. Learn more about his recommendations to strengthen the system.