Kidney Transplantation and "Sex Mismatch": A 10-Year Single-Center Analysis

The Emerging Role of Biological Sex in Cell Therapy for Spinal Cord Injury

Neural progenitor cell (NPC) transplantation is a promising potential therapy for replacing spinal cord neurons and glial cells following spinal cord injury (SCI). Despite the rapid advancement of NPC transplantation to SCI clinical trials, we still lack understanding of fundamental biology underlying how NPC grafts interact with the injured host nervous system. Our recent study demonstrated a potent effect of biological sex mismatch between donor and host on graft immune rejection. Here we discuss the implications of this study in the context of clinical trials for SCI, and important topics for future research in SCI cell transplantation.

The Role of Donor Sex in Females Undergoing Repeat Kidney Transplant: Does Prior Donor Sex Matter?

Female recipients of male donor kidneys are at increased risk for graft failure because of the HY antigen effect. However, whether prior transplant with a male donor impacts subsequent transplant outcomes is unknown. Therefore, the purpose of this study was to determine whether prior male-current male donor sex is associated with an increased risk of graft failure in female recipients.

Methods

We performed a cohort study of adult female recipients undergoing a second kidney transplant (2000-2017), identified using the Scientific Registry of Transplant Recipients. Using multivariable Cox models, we analyzed the risk of death-censored graft loss (DCGL) if the second transplant was from a male versus female kidney donor, conditional on donor sex at the time of the first transplant. In a secondary analysis, we stratified results by recipient age (>50 or ≤50 y) at the time of retransplant.

Results

Of 5594 repeat kidney transplants, 1397 (25.0%) developed DCGL. Overall, there was no association between first and second donor sex pairing and DCGL. A prior and current female donor (FD₁FD₂) posed a higher risk for DCGL in recipients aged >50 y at second transplant (hazard ratio,≤0.67, confidence interval 0.46-0.98, for all other donor combinations), but posed a lower risk if aged ≤50 y at retransplant (hazard ratio, ≥1.37, confidence interval 1.04-1.80, for all other donor combinations).

Conclusions

Overall, past-current donor sex pairing was not associated with DCGL in female recipients undergoing second kidney transplant; however, the risk with a past and current female donor was increased in older, and decreased in younger, female recipients at retransplant.

The Impact of Recipient Demographics on Outcomes from Living Donor Kidneys: Systematic Review and Meta-Analysis

Background and Aims: Recipient demographics affect outcomes after kidney transplantation. The aim of this study was to assess, for kidneys retrieved from living donors, the effect of recipient sex, ethnicity, and body mass index (BMI) on delayed graft function (DGF) and one-year graft function, incidence of acute rejection (AR), and recipient and graft survivals. Methods: A systematic review and meta-analysis was performed. EMBASE and MEDLINE databases were searched using algorithms through Ovid. Web of Science collection, BIOSIS, CABI, Korean Journal database, Russian Science Citation Index, and SciELO were searched through Web of Science. Cochrane database was also searched. Risk of bias was assessed using the NHBLI tools. Data analysis was performed using Revman 5.4. Mean difference (MD) and risk ratio (RR) were used in analysis. Results: A total of 5129 studies were identified; 24 studies met the inclusion criteria and were analysed. Female recipients were found to have a significantly lower serum creatinine 1-year-post renal transplantation (MD: −0.24 mg/dL 95%CI: −0.18 to −0.29 p < 0.01) compared to male recipients. No significant difference in survival between male and female recipients nor between Caucasians and Africans was observed (p = 0.08). However, Caucasian recipients had a higher 1-year graft survival compared to African recipients (95% CI 0.52−0.98) with also a lower incidence of DGF (RR = 0.63 p < 0.01) and AR (RR = 0.55 p < 0.01). Recipient obesity (BMI > 30) was found to have no effect on 1-year recipient (p = 0.28) and graft survival (p = 0.93) compared to non-obese recipients although non-obese recipients had a lower rate of DGF (RR = 0.65 p < 0.01) and AR (RR = 0.81 p < 0.01) compared to obese recipients. Conclusions: Gender mismatch between male recipients and female donors has negative impact on graft survival. African ethnicity and obesity do not to influence recipient and graft survival but negatively affect DGF and AR rates.

Disparities in chronic kidney disease-the state of the evidence

PURPOSE OF REVIEW

The purpose of this review was to assess the prevalence of United States chronic kidney disease (CKD) health disparities, focusing on racial/ethnic groups, immigrants and refugees, sex or gender, and older adults.

RECENT FINDINGS

There are major racial/ethnic disparities in CKD, with possible contributions from the social determinants of health, socioeconomics, and racial discrimination. Racial/ethnic minority patients experience faster progression to end-stage kidney disease (ESKD) and higher mortality predialysis, however, once on dialysis, appear to live longer. Similarly, men are quicker to progress to ESKD than women, with potential biological, behavioral, and measurement error factors. There is a lack of substantial evidence for intersex, nonbinary, or transgender patients. There are also strikingly few studies about US immigrants or older adults with CKD despite the fact that they are at high risk for CKD due to a variety of factors.

SUMMARY

As providers and scientists, we must combat both conscious and unconscious biases, advocate for minority patient populations, and be inclusive and diverse in our treatment regimens and provision of care. We need to acknowledge that sufficient evidence exists to change treatment guidelines, and that more is required to support the diversity of our patient population.