Utilization of Deceased Donor Kidneys to Initiate Living Donor Chains

Enzymatic conversion of human blood group A kidneys to universal blood group O

ABO blood group compatibility restrictions present the first barrier to donor-recipient matching in kidney transplantation. Here, we present the use of two enzymes, FpGalNAc deacetylase and FpGalactosaminidase, from the bacterium Flavonifractor plautii to enzymatically convert blood group A antigens from the renal vasculature of human kidneys to 'universal' O-type. Using normothermic machine perfusion (NMP) and hypothermic machine perfusion (HMP) strategies, we demonstrate blood group A antigen loss of approximately 80% in as little as 2 h NMP and HMP. Furthermore, we show that treated kidneys do not bind circulating anti-A antibodies in an ex vivo model of ABO-incompatible transplantation and do not activate the classical complement pathway. This strategy presents a solution to the donor organ shortage crisis with the potential for direct clinical translation to reduce waiting times for patients with end stage renal disease.

Long term simulation analysis of deceased donor initiated chains in kidney exchange programs

Kidney exchange programs (KEPs) aim to find compatible kidneys for recipients with incompatible donors. Patients without a living donor depend upon deceased donor (DD) donations to get a kidney transplant. In India, a ©DD donates kidneys directly to a©DD wait-list. The idea of initiating an exchange chain starting from a ©DD kidney is proposed in a few articles (and executed in Italy in 2018), but no mathematical formulation has been given for this merger. We have introduced an integer programming formulation that creates ©DD-initiated chains, considering both paired exchange registry and ©DD allocations simultaneously and addressing the overlap issue between the exchange registry and ©DD wait-list as recipients can register for both registries independently. A long-term simulation study is done to ©analyse the gain of these DD-initiated chains over time. It suggests that even with small numbers of ©DDs, these chains can significantly increase potential transplants.

[Perspectives for future development of the kidney paired donation programme in France]

Almost one third of kidney donation candidates are incompatible (HLA and/or ABO) with their directed recipient. Kidney paired donation allows potential donors to be exchanged and gives access to a compatible kidney transplant. The Bioethics Law of 2011 authorised kidney paired donation in France with reciprocity between 2 incompatible "donor-recipient" pairs. A limited number of transplants have been performed due to a too restricted authorization compared to other European practices. This study presents the perspectives of the new Bioethics Law, enacted in 2021, which increases the authorised practices for kidney paired donation in France. The two simulated evolutions are the increase of the number of pairs involved in a kidney paired donation to 6 (against 2 currently) and the use of a deceased donor as a substitution to one of living donor. Different scenarios are simulated using data from the Agence de la Biomedecine; incompatible pairs registered in the kidney paired donation programme in France between December 2013 and February 2018 (78 incompatible pairs), incompatible transplants performed during the same period (476 incompatible pairs) and characteristics of deceased donors as well as proposals made over this period. Increasing the number of pairs has a limited effect on the number of transplants, which increases from 18 (23% of recipients) in the current system to 25 (32% of recipients) when 6 pairs can be involved. The use of a deceased donor significantly increases the number of transplants to 41 (52% of recipients). This study makes it possible to evaluate the increase in possibilities of kidney transplants by kidney paired donation following the new bioethics law. A working group and an information campaign for professionals and patients will be necessary for its implementation.

Kidney Paired Donation Chains Initiated by Deceased Donors

Introduction

Rather than generating 1 transplant by directly donating to a candidate on the waitlist, deceased donors (DDs) could achieve additional transplants by donating to a candidate in a kidney paired donation (KPD) pool, thereby, initiating a chain that ends with a living donor (LD) donating to a candidate on the waitlist. We model outcomes arising from various strategies that allow DDs to initiate KPD chains.

Methods

We base simulations on actual 2016 to 2017 US DD and waitlist data and use simulated KPD pools to model DD-initiated KPD chains. We also consider methods to assess and overcome the primary criticism of this approach, namely the potential to disadvantage blood type O-waitlisted candidates.

Results

Compared with shorter DD-initiated KPD chains, longer chains increase the number of KPD transplants by up to 5% and reduce the number of DDs allocated to the KPD pool by 25%. These strategies increase the overall number of blood type O transplants and make LDs available to candidates on the waitlist. Restricting allocation of blood type O DDs to require ending KPD chains with LD blood type O donations to the waitlist markedly reduces the number of KPD transplants achieved.

Conclusion

Allocating fewer than 3% of DD to initiate KPD chains could increase the number of kidney transplants by up to 290 annually. Such use of DDs allows additional transplantation of highly sensitized and blood type O KPD candidates. Collectively, patients of each blood type, including blood type O, would benefit from the proposed strategies.

Equity or Equality? Which Approach Brings More Satisfaction in a Kidney-Exchange Chain?

In United States (U.S.), government-funded organizations, such as NLDAC, reimburse travel and subsistence expenses incurred during living-organ donation process. However, in Iran, there is a non-governmental organization called Iranian Kidney Foundation (IKF) that funds the direct and indirect costs of donors through charitable donations and contributions from participants in the exchange program. In this article, for countries outside the U.S. that currently use an equality approach, we propose a potential new compensation-apportionment approach (equitable approach) for kidney-exchange chains and compare it with the currently available system (equality approach) in terms of the apportionment of compensation in a kidney-exchange chain to cover the expenses incurred by the initiating living donor of the chain in the act of donation. To this end, we propose a mechanism to apportion compensation among all participating pairs based on the equity approach by utilizing a prediction model to calculate the probability of graft survival in each transplant operation. These probabilities are then used to define the utility of any transplantation, considering the quality of each pair’s donated and received kidney in the chain. Afterward, the corresponding cost is apportioned by a mechanism based on the normalized differences between the utility of donated and received kidneys for each incompatible pair of the chain. In summary, we demonstrate that by utilizing the equitable approach, there is more fairness and equity in the allocation of resources in organ-procurement systems, which results in more satisfaction among incompatible pairs. Additional future prospective studies are needed to assess this proposed equitable approach for kidney-exchange chains in countries outside the U.S., such as Iran, that currently use an equality approach.

Efficient Kidney Exchange with Dichotomous Preferences

This paper studies a general kidney exchange model with compatible patient-donor pairs, incompatible patient-donor pairs, single donors, and patients on the waiting list. We derive an explicit formula of the maximal number of feasible kidney transplants under several sizes of cycles and chains of exchange, analyze the effect of different ways of exchange on efficiency, and provide substantial simulation results based on the USA data. Our results further show that kidney exchange can be decentralized for relatively large populations, and that allowing compatible pairs and single donors to exchange with incompatible pairs can significantly increase the number of feasible kidney transplants. A more general model of two-category type-compatible exchanges is also established.

Data and optimisation requirements for Kidney Exchange Programs

Kidney Exchange Programs (KEP) are valuable tools to increase the options of living donor kidney transplantation for patients with end-stage kidney disease with an immunologically incompatible live donor. Maximising the benefits of a KEP requires an information system to manage data and to optimise transplants. The data input specifications of the systems that relate to key information on blood group and Human Leukocyte Antigen (HLA) types and HLA antibodies are crucial in order to maximise the number of identified matched pairs while minimising the risk of match failures due to unanticipated positive crossmatches. Based on a survey of eight national and one transnational kidney exchange program, we discuss data requirements for running a KEP. We note large variations in the data recorded by different KEPs, reflecting varying medical practices. Furthermore, we describe how the information system supports decision making throughout these kidney exchange programs.

Non-simultaneous kidney exchange cycles in resource-restricted countries without non-directed donation - a prospective single-center cohort study

Recent reports suggest that bridge-donor reneging is rare (1.5%) in non-simultaneous kidney exchange chains. However, in developing countries, the non-directed donors who would be needed to initiate chains are unavailable, and furthermore, limited surgical space and resources restrain the feasibility of simultaneous kidney exchange cycles. Therefore, the aim of this study was to evaluate the bridge-donor reneging rate during non-simultaneous kidney exchange cycles (NSKEC) in a prospective single-center cohort study (n = 67). We describe the protocol used to prepare co-registered donor-recipient pairs for non-simultaneous surgeries, in an effort to minimize the reneging rate. In addition, in order to protect any recipients who might be left vulnerable by this arrangement, we proposed the use of standard criteria deceased-donor kidneys to rectify the injustice in the event of any bridge-donor reneging. We report 17 successful NSKEC resulting in 67 living-donor kidney transplants (LDKT) using 23 bridge-donors without donor renege and no intervening pairs became unavailable. We propose that NSKEC could increase LDKT, especially for difficult-to-match sensitized pairs (25 of our 67 pairs) in countries with limited transplantation resources. Our study confirms that NSKEC can be safely performed with careful patient-donor selection and non-anonymous kidney exchanges.

Deceased donors as nondirected donors in kidney paired donation

As proof of concept, we simulate a revised kidney allocation system that includes deceased donor (DD) kidneys as chain-initiating kidneys (DD-CIK) in a kidney paired donation pool (KPDP), and estimate potential increases in number of transplants. We consider chains of length 2 in which the DD-CIK gives to a candidate in the KPDP, and that candidate's incompatible donor donates to theDD waitlist. In simulations, we vary initial pool size, arrival rates of candidate/donor pairs and (living) nondirected donors (NDDs), and delay time from entry to the KPDP until a candidate is eligible to receive a DD-CIK. Using data on candidate/donor pairs and NDDs from the Alliance for Paired Kidney Donation, and the actual DDs from the Scientific Registry of Transplant Recipients (SRTR) data, simulations extend over 2 years. With an initial pool of 400, respective candidate and NDD arrival rates of 2 per day and 3 per month, and delay times for access to DD-CIK of 6 months or less, including DD-CIKs increases the number of transplants by at least 447 over 2 years, and greatly reduces waiting times of KPDP candidates. Potential effects on waitlist candidates are discussed as are policy and ethical issues.

Does HLA matching matter in the modern era of renal transplantation?

Children with end-stage kidney disease should be offered the best chance for future survival which ideally would be a well-matched pre-emptive kidney transplant. Paediatric and adult practice varies around the world depending on geography, transplant allocation schemes and different emphases on living (versus deceased) donor renal transplantation. Internationally, paediatric patients often have priority in allocation schemes and younger donors are preferentially allocated to paediatric recipients. HLA matching can be difficult and may result in longer waiting times. Additionally, with improved surgical techniques and modern immunosuppressive regimens, how important is the contribution of HLA matching to graft longevity? In this review, we discuss the relative importance of HLA matching compared with donor quality; and long-term patient outcomes including re-transplantation rates. We share empirical evidence that will be useful for clinicians and families to make decisions about best donor options. We discuss why living donation still provides the best allograft survival outcomes and what to do in the scenario of a highly mismatched living donor.

Kidney exchange strategies: new aspects and applications with a focus on deceased donor-initiated chains

Kidney paired donation (KPD) is a valuable way to overcome immunological incompatibility in the context of living donation, and several strategies have been implemented to boost its development. In this article, we reviewed the current state of the art in this field, with a particular focus on advanced KPD strategies, including the most recent idea of initiating living donor (LD) transplantation chains with a deceased donor (DD) kidney, first applied successfully in 2018. Since then, Italy has been running a national programme in which a chain-initiating kidney is selected from a DD pool and allocated to a recipient with an incompatible LD, and the LD's kidney is transplanted into a patient on the waiting list (WL). At this stage, since the ethical and logistic issues have been managed appropriately, KPD starting with a DD has proved to be a feasible strategy. It enables transplants in recipients of incompatible pairs without the need for desensitizing and also benefits patients on the WL who are allocated chain-ending kidneys from LDs (prioritizing sensitized patients and those on the WL for longer).

KPDGUI: An interactive application for optimization and management of a virtual kidney paired donation program

BACKGROUND AND OBJECTIVES

The aim in kidney paired donation (KPD) is typically to maximize the number of transplants achieved through the exchange of donors in a pool comprising incompatible donor-candidate pairs and non-directed (or altruistic) donors. With many possible options in a KPD pool at any given time, the most appropriate set of exchanges cannot be determined by simple inspection. In practice, computer algorithms are used to determine the optimal set of exchanges to pursue. Here, we present our software application, KPDGUI (Kidney Paired Donation Graphical User Interface), for management and optimization of KPD programs.

METHODS

While proprietary software platforms for managing KPD programs exist to provide solutions to the standard KPD problem, our application implements newly investigated optimization criteria that account for uncertainty regarding the viability of selected transplants and arrange for fallback options in cases where potential exchanges cannot proceed, with intuitive resources for visualizing alternative optimization solutions.

RESULTS

We illustrate the advantage of accounting for uncertainty and arranging for fallback options in KPD using our application through a case study involving real data from a paired donation program, comparing solutions produced under different optimization criteria and algorithmic priorities.

CONCLUSIONS

KPDGUI is a flexible and powerful tool for offering decision support to clinicians and researchers on possible KPD transplant options to pursue under different user-specified optimization schemes.

The 6-year clinical outcomes for patients registered in a multiregional United States Kidney Paired Donation program - a retrospective study

We examined what happened during a 6-year period to 1121 end-stage renal disease patients who registered with their willing/incompatible living donors for kidney exchanges with the Alliance for Paired Donation (APD). Of all patients, 65% were transplanted: 37% in kidney paired donation (APD-KPD, APD-other-KPD); 10% with compatible live donors (APD-LD); and 18% with deceased donors (APD-DD). The remaining patients were withdrawn (sick/died/others; 15%), or were still waiting (20%). For those patients with a cPRA 0-94%, 72% received a transplant. In contrast, only 49% of very highly sensitized (VHS; cPRA 95-100%) were transplanted. Of the VHS patients, 50% were transplanted by KPD/APD-LD while 50% benefited through prioritization of deceased donors in the modified kidney allocation system (KAS introduced in 2014). All APD transplanted groups had similar death-censored 4-year graft survivals as their relevant Organ Procurement and Transplantation Network (OPTN) groups. It is noteworthy that VHS graft and patient survival results were comparable to less sensitized and nonsensitized patients. All patients should be encouraged to search for compatible donors through different options. Expanding the donor pool through KPD and the new KAS of the OPTN increases the likelihood of transplantation for VHS patients.

Living Kidney Donation: Strategies to Increase the Donor Pool

End-stage renal disease (ESRD) is a significant health care burden. Although kidney transplantation is the optimal treatment modality, less than 25% of waiting list patients are transplanted because of organ shortage. Living kidney donation can lead to better recipient and graft survival and increase the number of donors. Not all ESRD patients have potential living donors, and not all living donors are a compatible match to recipients. Kidney paired exchanges allow incompatible pairs to identify compatible living donors for living donor kidney transplants for multiple recipients. Innovative modifications of kidney paired donation can increase the number of kidney transplants, with excellent outcomes.

The first 9 years of kidney paired donation through the National Kidney Registry: Characteristics of donors and recipients compared with National Live Donor Transplant Registries

The practice of kidney paired donation (KPD) is expanding annually, offering the opportunity for live donor kidney transplant to more patients. We sought to identify if voluntary KPD networks such as the National Kidney Registry (NKR) were selecting or attracting a narrower group of donors or recipients compared with national registries. For this purpose, we merged data from the NKR database with the Scientific Registry of Transplant Recipients (SRTR) database, from February 14, 2008, to February 14, 2017, encompassing the first 9 years of the NKR. Compared with all United Network for Organ Sharing (UNOS) live donor transplant patients (49 610), all UNOS living unrelated transplant patients (23 319), and all other KPD transplant patients (4236), the demographic and clinical characteristics of NKR transplant patients (2037) appear similar to contemporary national trends. In particular, among the NKR patients, there were a significantly (P < .001) greater number of retransplants (25.6% vs 11.5%), hyperimmunized recipients (22.7% vs 4.3% were cPRA >80%), female recipients (45.9% vs 37.6%), black recipients (18.2% vs 13%), and those on public insurance (49.7% vs 41.8%) compared with controls. These results support the need for greater sharing and larger pool sizes, perhaps enhanced by the entry of compatible pairs and even chains initiated by deceased donors, to unlock more opportunities for those harder-to-match pairs.

Kidney exchange transplantation current status, an update and future perspectives

Kidney exchange transplantation is well established modality to increase living donor kidney transplantation. Reasons for joining kidney exchange programs are ABO blood group incompatibility, immunological incompatibility (positive cross match or donor specific antibody), human leukocyte antigen (HLA) incompatibility (poor HLA matching), chronological incompatibility and financial incompatibility. Kidney exchange transplantation has evolved from the traditional simultaneous anonymous 2-way kidney exchange to more complex ways such as 3-way exchange, 4-way exchange, n-way exchange,compatible pair, non-simultaneous kidney exchange,non-simultaneous extended altruistic donor, never ending altruistic donor, kidney exchange combined with desensitization, kidney exchange combined with ABO incompatible kidney transplantation, acceptable mismatch transplant, use of A2 donor to O patients, living donor-deceased donor list exchange, domino chain, non-anonymous kidney exchange, single center, multicenter, regional, National, International and Global kidney exchange. Here we discuss recent advances in kidney exchanges such as International kidney exchange transplantation in a global environment, three categories of advanced donation program, deceased donors as a source of chain initiating kidneys, donor renege myth or reality, pros and cons of anonymity in developed world and (non-) anonymity in developing world, pros and cons of donor travel vs kidney transport, algorithm for management of incompatible donor-recipient pairs and pros and cons of Global kidney exchange. The participating transplant teams and donor-recipient pairs should make the decision by consensus about kidney donor travel vs kidney transport and anonymity vs non-anonymity in allocation as per local resources and logistics. Future of organ transplantation in resource-limited setting will be liver vs kidney exchange, a legitimate hope or utopia?

Swaps and Chains and Vouchers, Oh My!: Evaluating How Saving More Lives Impacts the Equitable Allocation of Live Donor Kidneys

Live kidney donation involves a delicate balance between saving the most lives possible and maintaining a transplant system that is fair to the many thousands of patients on the transplant waiting list. Federal law and regulations require that kidney allocation be equitable, but the pressure to save patients subject to ever-lengthening waiting times for a transplant has been swinging the balance toward optimizing utility at the expense of justice. This article traces the progression of innovations created to make optimum use of a patient's own live donors. It starts with the simplest - direct donation by family members - and ends with voucher donations, a very recent and unique innovation because the donor can donate 20 or more years before the intended recipient is expected to need a kidney. In return for the donation, the intended recipient receives a voucher that can be redeemed for a live kidney when it is needed. Other innovations that are discussed include kidney exchanges and list paired donation, which are used to facilitate donor swaps when donor/recipient pairs have incompatible blood types. The discussion of each new innovation shows how the equity issues build on each other and how, with each new innovation, it becomes progressively harder to find an acceptable balance between utility and justice. The article culminates with an analysis of two recent allocation methods that have the potential to save many additional lives, but also affirmatively harm some patients on the deceased donor waiting list by increasing their waiting time for a life-saving kidney. The article concludes that saving additional lives does not justify harming patients on the waiting list unless that harm can be minimized. It also proposes solutions to minimize the harm so these new innovations can equitably perform their intended function of stimulating additional transplants and extending the lives of many transplant patients.

PROviding Better ACcess To ORgans: A comprehensive overview of organ-access initiatives from the ASTS PROACTOR Task Force

The American Society of Transplant Surgeons (ASTS) PROviding better Access To Organs (PROACTOR) Task Force was created to inform ongoing ASTS organ access efforts. Task force members were charged with comprehensively cataloguing current organ access activities and organizing them according to stakeholder type. This white paper summarizes the task force findings and makes recommendations for future ASTS organ access initiatives.

A Kidney Graft Survival Calculator that Accounts for Mismatches in Age, Sex, HLA, and Body Size

BACKGROUND AND OBJECTIVES

Outcomes for transplants from living unrelated donors are of particular interest in kidney paired donation (KPD) programs where exchanges can be arranged between incompatible donor-recipient pairs or chains created from nondirected/altruistic donors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using Scientific Registry of Transplant Recipients data, we analyzed 232,705 recipients of kidney-alone transplants from 1998 to 2012. Graft failure rates were estimated using Cox models for recipients of kidney transplants from living unrelated, living related, and deceased donors. Models were adjusted for year of transplant and donor and recipient characteristics, with particular attention to mismatches in age, sex, human leukocyte antigens (HLA), body size, and weight.

RESULTS

The dependence of graft failure on increasing donor age was less pronounced for living-donor than for deceased-donor transplants. Male donor-to-male recipient transplants had lower graft failure, particularly better than female to male (5%-13% lower risk). HLA mismatch was important in all donor types. Obesity of both the recipient (8%-18% higher risk) and donor (5%-11% higher risk) was associated with higher graft loss, as were donor-recipient weight ratios of <75%, compared with transplants where both parties were of similar weight (9%-12% higher risk). These models are used to create a calculator of estimated graft survival for living donors.

CONCLUSIONS

This calculator provides useful information to donors, candidates, and physicians of estimated outcomes and potentially in allowing candidates to choose among several living donors. It may also help inform candidates with compatible donors on the advisability of joining a KPD program.

Past, present and future of kidney paired donation transplantation in India

One third of healthy willing living kidney donors are rejected due to ABO blood group incompatibility and donor specific antibody. This increases pre-transplant dialysis duration leading to increased morbidity and mortality on the kidney transplantation waiting list. Over the last decade kidney paired donation is most rapidly increased source of living kidney donors. In a kidney transplantation program dominated by living donor kidney transplantation, kidney paired donation is a legal and valid alternative strategy to increase living donor kidney transplantation. This is more useful in countries with limited resources where ABO incompatible kidney transplantation or desensitization protocol is not feasible because of costs/infectious complications and deceased donor kidney transplantation is in initial stages. The matching allocation, ABO blood type imbalance, reciprocity, simultaneity, geography were the limitation for the expansion of kidney paired donation. Here we describe different successful ways to increase living donor kidney transplantation through kidney paired donation. Compatible pairs, domino chain, combination of kidney paired donation with desensitization or ABO incompatible transplantation, international kidney paired donation, non-simultaneous, extended, altruistic donor chain and list exchange are different ways to expand the donor pool. In absence of national kidney paired donation program, a dedicated kidney paired donation team will increase access to living donor kidney transplantation in individual centres with team work. Use of social networking sites to expand donor pool, HLA based national kidney paired donation program will increase quality and quantity of kidney paired donation transplantation. Transplant centres should remove the barriers to a broader implementation of multicentre, national kidney paired donation program to further optimize potential of kidney paired donation to increase transplantation of O group and sensitized patients. This review assists in the development of similar programs in other developing countries.

Kidney paired exchange and desensitization: Strategies to transplant the difficult to match kidney patients with living donors

With organs in short supply, only a limited number of kidney transplants can be performed a year. Live donor donation accounts for 1/3rd of all kidney transplants performed in the United States. Unfortunately, not every donor recipient pair is feasible because of Human leukocyte antigen (HLA) sensitization and ABO incompatibility. To overcome these barriers to transplant, strategies such as kidney paired donation (KPD) and desensitization have been developed. KPD is the exchange of donors between at least two incompatible donor-recipient pairs such that they are now compatible. Desensitization is the removal of circulating donor specific antibodies to prevent graft rejection. Regardless of the treatment strategy, highly sensitized patients whose calculated panel reactive antibody (cPRA) is ≥95% remain difficult to transplant with match rates as low as 15% in KPD pools. Desensitization has proved to be difficult in those with high antibody titers. A novel approach is the combination of both KPD and desensitization to facilitate compatible and successful transplantation. A highly sensitized patient can be paired with a better immunological match in the KPD pool and subsequently desensitized to a lesser degree. This article reviews the current progress in KPD and desensitization and their use as a combined therapy.