Abstract

Background and Objectives

Adequate representation of donors from diverse ancestral populations in blood, stem cell and organ transplantation is critical to ensuring equitable access to these lifesaving therapies. Because of population-level differences in genetic markers, patients from racialized groups may have unique transfusion and transplantation needs. However, racialized populations remain underrepresented as donors, exacerbating existing health inequities.

Materials and Methods

This narrative review synthesizes the factors contributing to disparities in donor representation across donation products, identifying common barriers and proposing potential solutions.

Results

Racialized populations are significantly underrepresented in donor pools across all donation types, limiting access to optimal donation products and increasing the risk of adverse outcomes. Common barriers to donation for racialized peoples include healthcare mistrust, lack of knowledge and sociocultural factors such as religious beliefs and language barriers. Facilitators include culturally tailored education, community engagement and policy-driven initiatives.

Conclusion

Addressing disparities in donor representation requires a multifaceted approach integrating education, community trust-building and systemic policy changes. Cross-disciplinary efforts are essential to diversify donor bases and reduce inequities in access to optimal donation products.

Highlights

• Although ancestrally diverse donor bases are needed to optimize recipient outcomes, racialized populations are underrepresented as donors across donation products.
• Common barriers to donation impacting racialized peoples include mistrust in health care, knowledge gaps and sociocultural factors.
• Addressing donation disparities requires an integrated approach that combines culturally tailored education, trust-building and community engagement, as well as systemic policy changes to diversify donor bases.

INTRODUCTION

To meet patient needs for blood, stem cell and organ and tissue donations, blood collection centres and stem cell/organ and tissue donor registries work to recruit and maintain diverse donor pools. Guiding this effort is the knowledge that donors from different ancestral populations can have unique genetic markers that are relevant in matching patients to optimal donation products [1–3]. However, racialized populations face unique barriers to donation and are underrepresented as donors across donation products [4–6]. Moreover, efforts to characterize and address barriers to donation impacting racialized peoples have largely been pursued in silos within the transfusion medicine, haematopoietic cell transplantation and solid organ transplantation fields. To our knowledge, no prior works have highlighted the interrelated nature of these challenges or outlined efforts needed to overcome them. Accordingly, this narrative review of peer-reviewed publications explores the factors and commonalities underlying disparities in donor representation across donation products and proposes potential solutions.

MATERIALS AND METHODS

This review adopts a narrative approach to examine disparities in donor representation across blood, stem cell and organ/tissue donation products. While not exhaustive, the references included (English language articles published during 1995–2025) were selected as representative examples to highlight commonalities and recurring themes in the literature. We focus specifically on disparities in donor pools for red blood cells (RBCs), haematopoietic stem cells (both adult donor and umbilical cord blood grafts) and kidney donation, with disparities in access to other donation products [7–9] lying outside the scope of this review. Of note, the review team collectively possesses lived experience developing and evaluating evidence-based approaches to engage racialized and underserved populations in donation, across diverse contexts. This experience informed both the identification, selection and interpretation of references as well as the writing of this review.

TERMINOLOGY RELATED TO HEALTH EQUITY

We define the key health equity terms for this review in Table 1. These definitions are particularly important because prior literature has used some of these terms (e.g., race, ethnicity and ancestry) inconsistently, which can interfere with characterizing and addressing disparities.

TABLE 1. Definitions of health equity terms.

Terms	Definitionsa
Race	A socio-politically constructed system for classifying and ranking human beings according to subjective beliefs about shared ancestry based on perceived innate biological similarities.
Ethnicity	The claim to shared heritage, often based on perceived cultural similarities (e.g., in language, religion, beliefs/customs).
Ancestry	The genetic line of descent of an individual or group of people. While race and ethnicity can correlate with ancestry, they each capture different information. Race and ethnicity are self or socially ascribed whereas ancestry better predicts the inheritance of certain genetic variants.
Racialization	The process by which societies construct races as real, different and unequal in ways that matter to economic, political or social life.
Underserved	Populations that are disadvantaged in relation to other groups due to societal/structural obstacles and disparities.
Underrepresented	Describes a subset of a population that holds a smaller percentage within a significant subgroup.
Structural racism	Structures, policies, practices and norms that lead to disadvantages experienced by people from specific racial/ethnic groups.
Discrimination	The unequal treatment of individuals based on, but not limited to, factors such as race, gender, social class, sexual orientation, physical ability and religion.
Intersectionality	A framework for understanding how overlapping systems of oppression and discrimination, such as those based on race, gender and ethnicity, impact individuals and communities.

• a Definitions adapted from the National Institutes of Health [10] and the American Medical Association [11].

Although race and ethnicity are social constructs, there are genetic reasons for engaging members of underserved populations in donation. Race and ethnicity often serve as imperfect but practical surrogates for genetic ancestry. Different ancestral populations have varying allele frequencies, which are crucial to meeting the needs of increasingly diverse patient populations. Understanding these nuances is essential for improving practices, building trust within these communities and diversifying donor bases.

RACIALIZED DONORS ARE NEEDED AND UNDERREPRESENTED ACROSS DONATION PRODUCTS

Figure 1 summarizes the need for and underrepresentation of diverse donors across blood, stem cell and kidney donor pools.

FIGURE 1

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The need for and underrepresentation of diverse donors across blood, stem cell and kidney donation products. HLA, human leukocyte antigen.

Blood

The distribution of RBC antigen expression varies across different blood groups and racial populations. For example, such differences across Duffy expression are striking: 68% of peoples from African, Caribbean and Black (ACB) populations are negative for both Fya and Fyb, whereas 34% people of European ancestry are negative only for Fya and 17% lack only Fyb [12–14]. Similar differences are also observed in antigen expression for Kell, with the Kp(a+b–) phenotype almost always being found in people of European ancestry, and Js(a+b–) almost exclusively found in individuals from ACB populations [3]. These differences are clinically important, as they impact the risk of alloimmunization following blood transfusion, particularly for patients with sickle cell disease [13]. For this reason, American Society of Haematology guidelines recommend prophylactic antigen matching for Rh (C, E, or C/c, E/e) and K antigen for patients with sickle cell disease [15]; also note that extended red cell antigen matching for Jka/Jkb, Fya/Fyb and S/s may provide further protection from alloimmunization. However, because individuals from specific racialized populations are underrepresented in blood donor pools, it may not be possible to transfuse patients with non-ABO antigen-matched blood. Consequently, patients from these populations face an increased risk of alloimmunization [6, 16]. For example, multiple analyses have shown that specific racialized and ethnic populations are underrepresented as blood donors in the United States [17], Canada [18] and the United Kingdom [19], with racial and ethnic populations comprising only 20%–30% or less of the donor pool, despite representing approximately one-third to one-half of the general population. Further exacerbating this issue are population differences in the utilization of blood. For example, individuals of African ancestry, in addition to having unique non-ABO blood antigen profiles and being underrepresented in blood donor pools, are also at higher risk of sickle cell anaemia, a condition that requires frequent blood transfusions. These challenges intersect to increase the risk of alloimmunization and the related clinical consequences for patients from these populations.

Stem cells

The majority of patients in need of allogeneic stem cell transplantation lack a suitable fully human leukocyte antigen (HLA)-matched donor in their family and require an alternative donor. These include 8/8 HLA-matched unrelated donors (URD), haploidentical related donors, cord blood grafts and mismatched (≤7/8) URDs. Of these options, 8/8 URDs are usually preferred if available. However, patients from underserved racialized populations face multiple levels of disparities in access to stem cell donors. Although patients are more likely to find an 8/8 URD from within their own ancestral group, most non-European ancestry populations are underrepresented as donors on individual and on the worldwide donor registry [4]. Exacerbating the lack of representation, specific populations (e.g., peoples of sub-Saharan African ancestry) have greater HLA diversity: a seminal study by Beatty et al. demonstrated that sub-Saharan African ancestry peoples have a greater degree of HLA polymorphism and, as a result, are less likely to find URDs at any given registry size [2]. Additionally, specific underserved racial populations also have greater donor attrition [20, 21]. These challenges intersect, resulting in the majority of non-European ancestry transplant candidates not receiving an 8/8 URD transplantation, with those who do receive one having older donors [22] and delayed time to transplantation [23, 24]. Non-European ancestry patients are also less likely to have optimal cord blood, haploidentical related or mismatched unrelated donor grafts [22, 25–27].

Organs and tissues (kidney)

Donor–recipient HLA matching in kidney transplantation has been shown to improve graft function and patient survival and reduce the risk of sensitization [1, 28–30]. For this reason, guidelines recommend HLA typing for major histocompatibility complex Class I and Class II (KDIGO Clinical Practice Guidelines Recommendation 3.3), in addition to ABO matching, when evaluating for donor compatibility [1]. However, because individuals from specific racialized populations (e.g., ACB, Indigenous, Hispanic, East Asian, South Asian) are underrepresented in kidney donor pools, finding compatible donors for patients from these populations can be more challenging. Studies from the United States show that racialized populations are underrepresented in both the living and deceased kidney donation pool [5, 31–35], with similar trends in Canada [36, 37] and the United Kingdom [38]. These disparities are further exacerbated by the racial and ethnic differences in kidney transplant utilization. In 2023, underserved racial and ethnic populations in the United States represented over half of the kidney transplant waiting list, despite comprising less than a quarter of the total population [31, 39]. This disparity is due in part to the greater burden of hypertension and diabetes in these underserved populations, contributing to higher risks of end-stage renal disease and increased need for kidney transplantation [40, 41]. These inequities extend across multiple stages of the transplantation process, including lower rates of physician referrals for transplant evaluation and placement on the waiting list [42, 43].

DIVERSE DONORS FACE UNIQUE BARRIERS AND FACILITATORS TO DONATION

Specific racialized populations face unique barriers and facilitators to donation of blood, stem cells and solid organs. However, additionally, there are also many common barriers and facilitators (summarized in Supporting Information 1) that impact multiple racialized populations, and which are relevant across donation products. Importantly, identified barriers and facilitators may not apply uniformly to different populations, and careful interpretation of these findings is paramount.

Important barriers that impact donor decisions across donation products include mistrust of health care, lack of knowledge and specific sociocultural beliefs. Multiple studies have shown that mistrust of health care impacts engagement of racialized peoples to donation [21, 36, 37, 44–53]. For example, a 2023 community-based qualitative study by Haw et al. examined the perspectives on blood donation of 23 ACB young adults in Canada, and found that participants expressed a general mistrust in blood product allocation [45]. This mistrust stemmed from historical instances of exploitation of ACB populations by healthcare systems, including the history surrounding the development and use of HeLa cells and the Tuskegee syphilis trials, both of which included Black individuals in research without their consent and negatively impacted the participants [54, 55]. A 2018 systematic review by Klinkenberg et al. [44], which examined barriers and facilitators to blood donation among sub-Saharan African migrants and minorities in high-income Western countries, identified multiple studies highlighting examples of mistrust, including those related to concerns of donor discrimination [56–59] (e.g., Black donors were more likely to report worse staff treatment and longer wait times compared to donors of European descent, with these perceptions of discrimination negatively affecting their willingness to donate).

Additionally, multiple studies have highlighted the need for donation education, across donation products, especially with Black, Indigenous, Hispanic, East Asian and South Asian communities. Specific knowledge gaps identified included the need for diverse donor products, the donation process and donor eligibility criteria [36, 37, 44, 45, 48, 50, 60, 61]. These knowledge gaps can also contribute to reluctance surrounding discussions on donation in the community.

Examples of barriers related to sociocultural beliefs and views include religious and cultural beliefs, language barriers and parental involvement in decision making. Across donation products, compared with White populations, specific racialized and ethnic groups (e.g., ACB, Indigenous, Hispanic, Asian) were more likely to attribute greater importance to religious beliefs in influencing their decision to donate and cite religious objections as a deterrent [21, 34, 36, 37, 47–49, 52]. However, this also varied across groups (e.g., ACB, South Asian, East Asian, Middle Eastern), with some religious and cultural beliefs serving as facilitators to donation. Furthermore, among blood donors, language barriers were reported as a potential challenge for those who spoke English as an additional language, particularly because key resources, such as donor questionnaires, were not readily available in other languages [45, 61].

For Indigenous, Hispanic and Asian groups considering stem cell and kidney donation, parental involvement in decision making was cited as a prominent barrier. Individuals from these groups cited a stronger sense of family cohesion compared to people of European descent, with a stronger belief that family members should be consulted prior to the decision to donate [21, 45, 48, 49, 62].

Facilitators to blood, stem cell and kidney donation include both general donor retention programming and targeted recruitment efforts designed to meet the needs of specific populations. General donor retention programming efforts, such as additional contact with the registry, have been shown to be beneficial to donation across all races. However, they have a particularly positive influence on some racialized groups, with members of these groups more likely to report such outreach as a motivating factor [21, 51, 52, 61]. Recruitment approaches that emphasize the desire to contribute by helping someone in the community, engagement with community-specific values and a respect for religious beliefs and practices have been shown to resonate more strongly with specific racialized populations. For example, patients from ACB and Asian communities were more likely to join blood and stem cell registries if recruitment events were centred around specific individuals in need, or if it was clear that their donation would benefit someone in their own community [21, 60]. While religious beliefs are often cited as a barrier to discussion, they can also serve as facilitators. In faiths such as Buddhism, Islam and Confucianism, religious practices that emphasize charity, community service and helping those in need can promote donation [36, 60, 61]. Religious leaders and community members who actively endorse donation can also play a role in encouraging donation within these communities [61]. Across studies, many racialized populations considered public awareness campaigns engaging their specific community, with input from community advocates, to be important for all donor products [37, 44, 50, 51, 60, 61, 63, 64]. Participants of these studies brought up examples of campaigns being delivered through popular television talk shows, telenovelas, social media platforms, local institutions or through other multimedia resources as effective outreach strategies. These facilitators emphasize the need for culturally informed, community-based strategies in donor recruitment across products.

STRUCTURAL RACISM IN DONATION POLICIES

There are many examples of structural discrimination in donation policy and practice that impact donors and patients (see Figure 2 for summary). For example, in 2019, a multi-organizational task force published an infectious disease screening questionnaire for haematopoietic progenitor cell donors. This questionnaire guided donor assessment teams to ask potential stem cell donors if they had any associations with the continent of Africa, or if their sexual contacts had African heritage [65]. Similar questions have historically been included on screening questionnaires across donation products, in the United States [66], Canada [67, 68] and Europe [53]. Such questions are discriminatory: although they focus on donors’ geographic origins, they disproportionately impact donors from ACB populations and can exacerbate the historic mistrust between these populations and healthcare systems.

FIGURE 2

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Examples of structural racism in donation policies affecting donors and patients across blood, stem cell and kidney donation products.

There are also multiple systemic barriers to donation resulting from inequities in donor evaluation based on travel history or laboratory haematology. For example, although donation deferrals based on travel to malaria-endemic regions have been implemented to improve donation safety, it is also true that these deferrals disproportionately impact patients from ACB or Asian populations. We acknowledge that there are also policies that disproportionately impact European ancestry peoples; for example, blood donation deferrals based on geographic risk of exposure to variant Creutzfeldt–Jakob disease. However, such deferrals do not disproportionately exclude donors from underrepresented and needed populations. Furthermore, strict haemoglobin cutoffs to permit blood donation disproportionately impact patients from ACB, Asian and Middle Eastern populations, who are more likely to have sickle cell or thalassaemia trait with lower haemoglobin levels [45, 69–71]. Altogether, these systemic issues interfere with efforts to engage donors from diverse racialized populations and address disparities in representation across donor pools.

Structural discrimination in donation policies also impacts patients. Referral biases can limit patient access to haematopoietic and solid organ transplantation. Notably, a 2024 observational retrospective cohort study conducted across six organ-procurement organizations in the United States found significant disparities in the transition from referral to approach, approach to authorization and authorization to procurement, with Black patients facing lower odds at each step compared to non-Black patients [35]. Inequities in patient evaluation can also unfairly impact transplant eligibility assessments for patients from specific racialized populations. For example, many transplant programmes have used race-specific estimated glomerular filtration rate (eGFR) equations, which disproportionately increase the eGFR for Black patients, contributing to the underestimation of kidney disease severity and delays in appropriate interventions [72] as well as to racial disparities in kidney failure and mortality [73]. Biases in the donor selection process can also negatively impact patients from underserved racialized populations. For example, in allogeneic stem cell transplantation, for patients without a fully matched related donor, search prognosis scores (which estimate the likelihood of a patient having an available, matched unrelated donor) are important tools to help triage patients to either an 8/8 URD or an alternative donor (i.e., a haploidentical, cord blood or ≤7/8 URD graft) depending on the patient ancestry and preliminary URD search results [74]. However, these tools are not routinely used across transplant centres, and the failure to prioritize patients with poor search prognosis scores for alternative donors upfront can result in prolonged searches and increased risk of delayed transplantation (or disease relapse/comorbidities that preclude transplantation) [23]. This systemic issue disproportionately impacts patients of non-European ancestral groups, who are less likely to have an available 8/8 URD.

For many of the examples listed above, many organizations have made important strides in addressing the specific systemic barriers outlined (e.g., revising eGFR equations to remove race, implementing malarial nucleic acid tests to reduce deferrals for donors from malaria-endemic regions) [68]. However, it is important to note that while these barriers have in many contexts been reduced, the aftermath of these policies/practices likely remains. These consequences may include knowledge gaps and attitudinal impacts resulting from the specific policies/practices which should also be addressed.

AVENUES TO ADDRESS RACIAL DISPARITIES IN REPRESENTATION ACROSS DONOR POOLS

To address the challenges above, multiple potential solutions should be pursued concurrently (outlined in Figure 3). Efforts moving forward should involve collaboration with community advocates and donation-focused groups to raise awareness and educate diverse populations about the importance of donation. Key initiatives include donor education and engagement tailored to specific populations [62, 63, 75], advocacy for equitable healthcare policies [65], targeted efforts to address common donation barriers among racial and ethnic groups [76, 77] and education and training [78] (see Supporting Information 2). We highlight the non-profit organizations Black Donors Save Lives, which is led by and serves the ACB populations in Canada [63], Iranian Donors Save Lives, which is led by and serves Iranian peoples in Canada [64] and Stem Cell Club [79–89], for their efforts integrating community outreach, donor and healthcare professional education and advocacy to engage racialized peoples to donation.

FIGURE 3

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Solutions for addressing racial disparities in representation across blood, stem cells and organ/tissue donor pools.

Recruitment and retention programmes designed for specific populations are also essential [76]. Evidence shows that sustained engagement through culturally relevant education, storytelling by donors and highlighting the direct impact of donation on families and communities improves both recruitment and long-term retention. We highlight the Stem Cell Club’s donation-education TikTok library as an example of partnering with racialized populations to address disparities in representation on donor pools. Since 2020, Stem Cell Club has developed a large TikTok library to engage diverse young adults in haematopoietic stem cell donation. This resource, comprising hundreds of short videos featuring diverse performers, has generated hundreds of thousands of views and engagements across social media platforms and has been incorporated into national donor recruitment campaigns to educate the public and support donor registration [63, 64, 81, 82].

Further education and training initiatives are also needed to support equity in donation. We highlight the examples of the development of a transfusion medicine health equity and advocacy curriculum, presented to medical students as well as transfusion medicine and transplantation professionals [78, 90, 91], and the creation of multimedia resources in collaboration with transplantation experts and Black Canadian communities [63], whose impact has been measured through pre and post surveys measuring improvement in donation knowledge, willingness to donate and ambivalence.

Addressing systemic racism and its aftereffects is critical to advancing equity in donation practices. We acknowledge the efforts of Canadian Blood Services (CBS) in loosening restrictions on malaria risk through reducing wait times for travellers from malaria-endemic areas and working to implement a nucleic acid test for malaria [68, 92], as well as the work of the World Marrow Donor Association (WMDA) Donor Suitability Committee in developing guidelines for inclusive practices for safe and equitable donor assessments [93, 94]. In addition, targeted approaches are needed to improve access to optimal donation products for all patients. For example, the Children’s Hospital of Philadelphia piloted the ‘Blue Tag’ programme, which identified blood donations from African American donors for extended antigen and phenotype testing to facilitate better matches for patients with sickle cell disease [95]. Additionally, researchers have highlighted the availability of alternative donor grafts (including haploidentical [96], cord blood [97] and mismatched unrelated donor grafts [98]) to overcome disparities in access to matched adult donors, with algorithms [25] and tools [99] to optimize donor selection and improve patient outcomes. These measures represent meaningful progress in advancing equity for donors from vulnerable populations. However, these actions alone are not sufficient. Further efforts are needed to repair relationships with affected communities, including formal apologies and policy reforms that directly address historical harms. For instance, CBS has apologized to the Two-Spirit, lesbian, gay, bisexual, transgender/trans, queer or questioning, intersex and asexual (2SLGBTQ2IA+) community for the harm caused by previous donor eligibility policies [100]. Similar efforts are necessary from blood collection centres and donor registries to acknowledge and address the injustices experienced by racialized peoples, foster reconciliation and rebuild trust. Finally, efforts to address discriminatory policies and practices should be paired with efforts to evaluate the impact of those changes on the populations who had been impacted to guide future work.

Interdisciplinary collaboration is essential, given the commonalities across donation products. Conferences and shared platforms can provide opportunities for experts from diverse fields to come together and develop holistic strategies for overcoming these disparities [90, 91, 101]. Although this review focuses on race and ethnicity, it is important to acknowledge the intersectionality of other identities, such as 2SLGBTQ2IA+ status and gender, and their potential effects on donation outcomes [102–104]. Future research should explore these intersections to ensure that all communities are represented and supported in donation efforts.

CONCLUSION

In summary, our review highlights the shared challenges of racial and ethnic disparities in representation across donation products, as well as common barriers and facilitators affecting blood, stem cell and kidney donation. Although race and ethnicity are social constructs, they serve as imperfect proxies for genetic ancestry, which is crucial for compatible matching. Consequently, while people of all races and ethnicities are needed to register as potential donors, there is a unique and an increased need for donors from underserved racialized and ethnic populations. Future work is warranted across multiple domains to address these inequities, evaluate the effectiveness of current interventions and to develop and implement solutions in parallel—across blood, stem cell and solid organ donation—to promote equitable access to transplantation and transfusion therapies.

ACKNOWLEDGEMENTS

This work was supported by the Canadian Donation and Transplantation Research Program (CDTRP) and The Canadian Aid and Action Fund (CAAF) of the Royal College of Physicians and Surgeons of Canada.

W.B.F. conceived of the review. B.L. and W.B.F. wrote the manuscript. S.O., F.F., R.H. and L.S. led campaigns to engage racialized peoples to donation. B.L., M.-C.K., M.E. and W.B.F. designed the figures and supplementary package. All authors reviewed, critically revised and approved the final version of the manuscript.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.

DATA AVAILABILITY STATEMENT

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.