The influence of donor age and cause of death on corneal endothelial cell density

Donor Risk Factors and Environmental Conditions Associated With Poor-Quality Corneas: An Analysis of the Central Eye Bank of Iran (2018-2021)

PURPOSE

The purpose of this study was to investigate the donor risk factors and environmental conditions associated with poor-quality corneas using the database of the Central Eye Bank of Iran over 4 years.

METHODS

This cohort study was conducted on the recorded data of all donated corneas at the Central Eye Bank of Iran database from March 2018 to March 2022. Donors' characteristics and tissue variables were extracted from the database. The final corneal quality was determined based on slitlamp biomicroscopic observations and the results of specular microscopy. Environmental variables were also obtained from reliable resources. Risk factors for poor-quality corneas were calculated using logistic mixed-effect regression analysis. All analyses were performed with STATA 17.0. The significance level of 0.05 was considered for all the analyses.

RESULTS

The data of 20,625 eyes of 10,601 donors were evaluated. We found that donor age had an inverse correlation with endothelial cell density (r = -0.28, P < 0.001). The trend of donated corneal poor quality decreased between 2018 and 2021. Several factors, including intoxication (odds ratio [OR] = 1.29), obesity (OR = 1.34), diabetes mellitus (OR = 1.63), hypertension (OR = 1.52), and pseudophakic eyes (OR = 1.56), were associated with the poor quality of donated corneal tissues. The outdoor temperature over 26°C was associated with higher odds of poor corneal quality (OR = 1.31), whereas high relative humidity decreased the odds of poor corneal quality (OR = 0.82).

CONCLUSIONS

This study revealed that the cause of donor death, obesity, donor comorbidities, pseudophakia, and environmental factors could affect the corneal quality and make the donated corneas less suitable for transplantation.

Impact of culture media on primary human corneal endothelial cells derived from old donors

Corneal endothelial dysfunction is a major indication for corneal transplantation. However, a global shortage of donor corneal tissues and risks associated with corneal surgeries have prompted exploration of alternative options, including tissue-engineered grafts or cell injection therapy. Nonetheless, these approaches require a controlled culture of primary human corneal endothelial cells (HCEnCs). Although HCEnCs established from young donors are generally more proliferative and maintain a better phenotype, corneas from old donors are more frequently accessible from eye banks due to a lower corneal endothelial cell count than the necessary threshold required for transplantation. In this study, we investigated various culture media to evaluate which one is the most appropriate for stimulating the proliferation while maintaining cell morphology and function of HCEnCs derived from old donors (age >65 years). All experiments were performed on paired research-grade donor corneas, divided for the conditions under investigation in order to minimize the inter-donor variability. Cell morphology as well as expression of specific markers were assessed at both mRNA (CD166, SLC4A11, ATP1A1, COL8A1, α-SMA, CD44, COL1A1, CDKN2A, LAP2A and LAP2B) and protein (ZO-1, α-SMA, Ki67 and LAP2) levels. Results obtained showed how the Dual Media formulation maintained the hexagonal phenotype more efficiently than Single Medium, but cell size gradually increased with passages. In contrast, the Single Medium provided a higher proliferation rate and a prolonged in vitro expansion but acquired an elongated morphology. To summarize, Single medium and Dual media preserve morphology and functional phenotype of HCEnCs from old donor corneas at low passages while maintenance of the same cell features at high passages remains an active area of research. The new insights revealed within this work become particularly relevant considering that the elderly population a) is the main target of corneal endothelial therapy, b) represents the majority of corneal donors. Therefore, the proper expansion of HCEnCs from old donors is essential to develop novel personalised therapeutic strategies and reduce requirement of human corneal tissues globally.

Effect of Head Trauma-Related Deaths on Corneal Endothelial Cell Loss in Eye Bank Donors

PURPOSE

The purpose of this study was to examine the effect of head trauma-related deaths on corneal endothelial cell density (ECD) in eye bank donors.

METHODS

This is a retrospective study of 287 corneas from donors with causes of death secondary to motor vehicle accident with sustained head trauma (n = 50), gunshot wound to the head (n = 138), fall with sustained head trauma (n = 2), and non-head-related traumatic causes of death (n = 97). Donors older than age 50 years were excluded due to concern for undiagnosed Fuchs endothelial dystrophy as a potential confounder for the cause of endothelial cell loss. Donor characteristics, ECD, and focal endothelial cell loss on specular microscopy were compared between the groups. Donors in the head trauma and nonhead trauma groups were matched by age; there were 42 age-matched donors in both groups.

RESULTS

Age and ECD were negatively correlated (Pearson correlation coefficient = -0.57). Death-to-preservation time was not significantly different between the 2 groups ( P value = 0.59). The mean ECD in the head trauma group was 2859 ± 370 cells/mm 2 and 3041 ± 464 cells/mm 2 in the nonhead trauma group. The head trauma group had a lower ECD (178 ± 70 cells/mm 2 , P value = 0.013). After matching for age, the difference in ECD between the 2 groups was -94 ± 82 cells/mm 2 ( P value = 0.26). The adjusted odds of having focal endothelial cell loss was not statistically significant ( P value = 0.50) between the groups.

CONCLUSIONS

After statistical adjustments, there were no differences between the head trauma and nonhead trauma groups.

Comparison of Corneal Tissue Profile of Pseudophakic and Phakic Donors

PURPOSE

To compare the endothelial quality of corneas obtained from pseudophakic donors with age-matched phakic controls.

METHODS

Retrospective analysis of 100 corneas each from pseudophakic and phakic eyes with donor age ≥60 years in both the groups was performed. The endothelial cell density, coefficient of variation, and percentage of hexagonal cells obtained by specular microscopy were compared between the two groups. The cut-off level of endothelial cell density (ECD) taken for optical keratoplasty was 2,000 cells/mm2.

RESULTS

The male and female donors constituted 60% (n=120) and 40% (n=80), respectively. The mean age of the donors was 66.9±7.3 years in the phakic group and 69.9±7.7 years in pseudophakic group. The mean ECD in the phakic group was 2757.6±328.5 cells/mm2 and that in the pseudophakic group was 2225.5±471.9 cells/mm2 (P<0.0001). The mean coefficient of variation in the phakic group was 37.1±5.0 and that in the pseudophakic group was 38.6±11.1 (P=0.234). The mean percentage of hexagonality in the phakic group and the pseudophakic group was 52.0±6.4% and 51.2±7.2%, respectively (P=0.414). Both in univariate and multivariate linear regression analysis, age of the donor was found to be negatively associated in predicting ECD (P=0.002 and P=0.003, respectively). Sixty-nine and thirty-three corneas from the phakic and pseudophakic donor pool were used respectively.

CONCLUSION

Difference in ECD between the phakic and the pseudophakic donor group was found to be statistically significant. The ECD in the pseudophakic group was found to be above the cut-off limit required for keratoplasty. Hence, pseudophakic corneas may also be used for transplantation.

How to Predict the Suitability for Corneal Donorship?

Background: In Germany, more than one-third of donor corneas harvested are not suitable for transplantation. We evaluated the factors associated with the usability of donor corneas. Method: Data from 2032 consecutive donor corneas harvested at the Rhineland-Palatinate Eye Bank in Mainz, Germany, were retrospectively analyzed. Factors of interest were age, sex, lens status, cause of death, cardiopulmonary resuscitation (CPR), death-to-explantation-interval (DEI), and the influence of these factors on the proportion of discarded donor corneas. Factors associated with endothelial cell density (ECD) were analyzed in a linear regression mixed model. Results: Higher donor age, male gender, pseudophakic lens status, and longer DEI were associated with significantly reduced ECD. With respect to DEI, the estimated cell loss was 7 ± 2 cells/mm²/hour (p < 0.001). Age was associated with a lower ECD of 6 ± 2 cells/mm² per year (p = 0.001). Female ECD was 189 ± 44 cells/mm² higher than male ECD (p < 0.001). Pseudophakic eyes had 378 ± 42 cells/mm² less compared with phakic eyes (p < 0.001). Cause of death did not affect the ECD. Of note, 55% and 38% of corneas harvested on the second and third postmortem day, respectively, and 45% of corneas from donors older than 80 years were still suitable for transplantation. Conclusions: In the context of a growing need for donor corneas, we do not recommend limiting donor age and collection time to 24 h or excluding oncology donors, as is the practice in many countries. Therefore, we propose a mathematical model for better donor preselection.

Microtubule Stabilization Protects Hypothermia-Induced Damage to the Cytoskeleton and Barrier Integrity of the Corneal Endothelial Cells

Purpose: To determine the impact of hypothermia on the barrier function of donor corneal endothelium, thereby enhancing the success of corneal transplantation. Methods: Primary cultures of porcine endothelial cells were subjected to hypothermia (15 h; 4°C). The impact on microtubule assembly, peri-junctional actomyosin ring (PAMR), and ZO-1 was assessed by immunocytochemistry with and without pretreatment with a microtubule-stabilizing agent (Epothilone B; EpoB; 100 nM) and a p38 MAP kinase inhibitor (SB-203580; 20 μM). In addition, EpoB-loaded PLGA nanoparticles (ENPs) prepared by nanoprecipitation technique and coated with poly-L-lysine (PLL-ENPs) were administered one-time for sustained intracellular delivery of EpoB. Results: Exposure to hypothermia led to microtubule disassembly concomitant with the destruction of PAMR and the displacement of ZO-1 at the cellular periphery, suggesting a loss in barrier integrity. These adverse effects were attenuated by pretreatment with EpoB or SB-203580. PLL-ENPs possessed a zeta potential of ∼26 mV and a size of ∼110 nm. Drug loading and entrapment efficiency were 5% (w/w) and ∼87%, respectively, and PLL-ENPs showed a biphasic release in vitro: burst phase (1 day), followed by a sustained phase (∼4 weeks). Pretreatment with PLL-ENPs (0.4 mg/mL) for 24 h stabilized the microtubules and opposed the hypothermia-induced damage to PAMR and the redistribution of ZO-1. Conclusions: Hypothermia induces microtubule disassembly via activation of p38 MAP kinase and subsequently breaks down the barrier function of the endothelium. Sustained intracellular delivery of EpoB using nanoparticles has the potential to overcome endothelial barrier failure during prolonged cold storage of donor cornea.

Profile of donors and corneal tissue obtained through hospital cornea retrieval programme in a recently established eye bank of a tertiary care teaching hospital of Eastern India

Context:

There is a global need for quality eye banking practices and sensitization of primary care physicians toward corneal donation.

Aims:

To evaluate performance of a recently established eye bank (EB) and quality of corneas obtained, and identify areas of improvement during procurement and utilization of donor corneas.

Settings and Design:

This retrospective observational study is based on records of corneas collected through hospital cornea retrieval programme (HRCP) in the EB of a tertiary care institution during the first 2 years of its establishment.

Methods and Material:

Data on demographic characteristics of donors, death-preservation interval, specular microscopy parameters of corneas, indications for utilization, and reasons for non-utilization of corneas were collected.

Statistical Analysis Used:

Means, standard deviation, range, frequencies, and proportions were analyzed. Spearman's correlation coefficient and Kruskal–Wallis test were applied taking P < 0.05 as significant.

Results:

The EB retrieved 54 corneas from 27 donors with mean age 42.3 ± 24.2 years. All tissues were preserved in Cornisol®. Majority (50%) of transplantable tissues had an endothelial cell density (ECD) between 2,000 and 2,500 cells/mm². ECD decreased significantly with increasing age (Spearman's ρ -0.747, P < 0.001; Kruskal–Wallis P < 0.001). Overall utilization rate of tissues was 87.04% (47/54), and utilizable corneas (50/54, 92.6%) were mainly used for optical purposes (34/50, 68%).

Conclusions:

Successful HCRP of the recently established EB has shown considerable promise in terms of quality and utilisation of corneas. There is need for active involvement of primary care physicians in contributing to increasing voluntary eye donation through awareness, advocacy, and social mobilization.

Corneal endothelial cell density in patients receiving chemotherapy

PURPOSE

This study aimed to determine if the corneal endothelium was affected by chemotherapy.

METHODS

Chemotherapy patients were recruited to undergo specular microscopy before treatment and again at 1- and 2-year follow-up visits. One eye per patient, per follow-up, was selected for comparison to baseline.

RESULTS

Forty-six volunteers completed baseline and at least one follow-up assessment. From 51 eyes, there was no significant change in endothelial cell density for 41 eyes assessed at one year (M_D = 0.73%, 95% CI -1.33 to 2.78%) and 18 eyes at two years (M_D = 0.31%, 95% CI -3.53 to 4.15%).

CONCLUSION

Although other studies have shown that chemotherapy can adversely affect the corneal epithelium, this study showed no measurable change in endothelial cell density.

Effect of Donor Age on Graft Survival in Primary Penetrating Keratoplasty with Imported Donor Corneas

Purpose

To investigate the influence of donor age on corneal graft survival following primary penetrating keratoplasty (PK) with imported donor corneas.

Methods

The eyes of patients who underwent primary PK with imported donor corneas were classified retrospectively into two groups according to a donor-age cutoff of 65 years. Primary outcome measures were rejection-free graft survival and graft survival. Cox proportional hazard regression analysis was used to assess the factors affecting graft survival. Survival analysis was performed using the Kaplan-Meier method, while differences between groups were examined using a log-rank test. A subgroup analysis of low- and high-risk eyes according to preoperative diagnosis was also performed.

Results

A total of 140 eyes from 138 patients (age, 58 ± 18 years) were enrolled. Cox regression analysis revealed that the donor age of 65 years or older group presented an increased risk of both graft rejection and failure. Survival analysis revealed that rejection-free graft survival and graft survival rates were higher in eyes in the donor age of less than 65 years group. Finally, in the subgroup analysis, both rejection-free graft survival and graft survival rates were significantly higher in the donor age of less than 65 years group than in the donor age of 65 years or older group, but only in the low-risk subgroup.

Conclusions

Donor age may correlate with graft survival in primary PK performed with imported donor corneas. Donor age could be a considerable factor in primary PK with imported donor corneas, especially in preoperatively low-risk patients.

Translational and Regulatory Challenges of Corneal Endothelial Cell Therapy: A Global Perspective

Cell therapies are emerging as a unique class of clinical therapeutics in medicine. In 2015, Holoclar (ex vivo expanded autologous human corneal epithelial cells containing stem cells) gained the regulatory approval for treating limbal stem cell deficiency after chemical eye burn. This has set a precedent in ophthalmology and in medicine, reinforcing the therapeutic promise of cell therapy. However, to generalize and commercialize cell therapies on a global scale, stringent translational and regulatory requirements need to be fulfilled at both local and international levels. Over the past decade, the Singapore group has taken significant steps in developing human corneal endothelial cell (HCEnC) therapy for treating corneal endothelial diseases, which are currently the leading indication for corneal transplantation in many countries. Successful development of HCEnC therapy may serve as a novel solution to the current global shortage of donor corneas. Based on the experience in Singapore, this review aims to provide a global perspective on the translational and regulatory challenges for bench-to-bedside translation of cell therapy. Specifically, we discussed about the characterization of the critical quality attributes (CQA), the challenges that can affect the CQA, and the variations in the regulatory framework embedded within different regions, including Singapore, Europe, and the United States. Impact statement Functional corneal endothelium is critical to normal vision. Corneal endothelial disease-secondary to trauma, surgery, or pathology-represents an important cause of visual impairment and blindness in both developed and developing countries. Currently, corneal transplantation serves as the current gold standard for treating visually significant corneal endothelial diseases, although limited by the shortage of donor corneas. Over the past decade, human corneal endothelial cell therapy has emerged as a promising treatment option for treating corneal endothelial diseases. To allow widespread application of this therapy, significant regulatory challenges will need to be systematically overcome.

Endothelial Cell Count in Eye Bank Corneal Grafts: Impact of Death Cause and Donor Diseases

PURPOSE

The purpose of this study is to analyze the impact of death causes and documented donor diseases on initial endothelial cell counts (after retrieval) and the development of corneal graft endothelia during organ culture.

METHODS

The retrospective statistic analyses was conducted on a data set of 10,185 human corneas prepared at the Hamburg Eye Bank.

RESULTS

Although we observed that death by gunshot trauma or alcoholism seems to be associated with marginally higher endothelium cell counts (independently from donor age), we could prove that only donor age is a relevant predictive parameter for the initial cell-density of the endothelium and its development in vitro.

CONCLUSION

We conclude that an extension of prospective quality parameters for donor selection additional to donor age (such as individual causes of death) is not necessary.

Cataract surgery in aged patients: phacoemulsification or small-incision extracapsular cataract surgery

AIM

To evaluate the effects and safety of phacoemulsification (Phaco) or small-incision extracapsular cataract surgery (SICS) and intraocular lens (IOL) implantation for aged patients.

METHODS

Totally 137 aged patients (149 eyes) underwent cataract operation in the case of stable systemic condition, the blood pressure less than 160/95mmHg, blood glucose less than 8mmol/L, and under the help of electrocardiogram surveillance by anesthesiologists during the operation. 106 aged patients (114 eyes) underwent Phaco while 31 aged patients (35 eyes) underwent SICS. The postoperative visual acuity, corneal endothelial cell loss, surgery time and major complications were observed and analyzed retrospectively.

RESULTS

The best-corrected visual acuity(BCVA) of ≥0.6 was achieved in 135 eyes (92.6%) at 1 month postoperatively (χ(2)=259.730, P<0.001). For aged patients, both Phaco and SICS could significantly improve visual acuity with no significant difference (χ(2)=4.535, P>0.05). Postoperative corneal endothelial cell loss was 18.6%, in PHACO group, the rate was 18.5%; in SICS group, the rate was 19.0%, the difference of which was no significant (χ(2)=0.102, P>0.05). The surgery time was different in two groups. No severe complications occurred.

CONCLUSION

Both Phaco and SICS combined with IOL implantation for aged patients are effective and safe. Before surgery, detailed physical examination should be performed. When the systemic condition is stable, cataract surgery for aged patients is safe.

Longterm results of deep lamellar keratoplasty using grafts with endothelium

PURPOSE

To report the longterm results of deep lamellar keratoplasty (DLK) using grafts with their own endothelia.

METHODS

Fourteen eyes of 14 patients underwent DLK using grafts with endothelium. The average follow-up was approximately 80.0 months. Preoperative diagnoses included: corneal leukoma (five eyes); gelatinous drop-like corneal dystrophy (three eyes); Avellino corneal dystrophy (two eyes); corneal perforation (two eyes); corneal mucopolysaccharidosis (one eye), and keratoconus (one eye).

RESULTS

Corrected visual acuity was improved in 13 eyes (93%), but ruptures of Descemet's membrane occurred in six eyes (43%) and a double anterior chamber was found in five eyes (36%) postoperatively. Despite this, all grafts remained clear as a result of their functioning endothelia.

CONCLUSIONS

Deep lamellar keratoplasty using a graft with its own endothelium is a safe and valuable procedure with flexibility and feasibility that should suit corneal surgeons of all levels.

Corneal Transplant Survival after Onset of Severe Endothelial Rejection

PURPOSE

To evaluate corneal graft survival after onset of severe endothelial rejection after penetrating keratoplasty (PK).

DESIGN

Retrospective case series.

PARTICIPANTS

One hundred fifty-six patients (161 PKs) treated at a single center.

METHODS

Retrospective review of the medical records of every case of severe endothelial rejection admitted to the King Khaled Eye Specialist Hospital (KKESH) between January 1, 1998 and December 31, 2002. Patients for whom PK had been performed at KKESH between June 1, 1983 and December 31, 2002 and in whom at least 3 months of follow-up was available were included in the statistical analysis.

MAIN OUTCOME MEASURE

Graft survival.

RESULTS

One hundred fifty-seven PKs (152 patients) met the inclusion criteria and were included in the statistical analysis. Four PKs (4 patients) were excluded from the statistical analysis due to inadequate follow-up. The rejection episode was reversed during the first 3 months in 90 grafts (57.3%). By Kaplan-Meier analysis, graft survivals were 42.6% at 1 year and 36.1% at 3 years. The surgical indication for PK significantly correlated with likelihood of reversibility (P<0.001) and long-term graft survival (P<0.001). Risk factors associated with an increased risk of postrejection graft failure included increasing donor age (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.04-1.24; P = 0.004), increasing patient age (OR, 1.23; 95% CI, 1.11-1.35; P<0.001), and history of rejection episodes (P = 0.002).

CONCLUSION

Endothelial rejection is a serious complication of PK, with a high risk of graft failure.

Consent for corneal donation: the effect of age of the deceased, registered intent and which family member is asked about donation

AIM

To determine whether consent to corneal donation is related to which next of kin is asked to consent, the age of the potential donor and the indication about donation made by the deceased on their driving licence.

METHOD

The Lions New South Wales Eye Bank (Sydney, New South Wales, Australia) provides the corneal transplantation service for Australia's most populous state. Over the 18-month period from 1 July 2004 to 31 December 2005 for all requests for donation, records were kept of which next of kin was asked for consent, the age of the deceased and the indication about donation by the deceased on their driving licence.

RESULTS

Over the 18-month study period, 841 people were approached about corneal donation. 63.2% of those people approached gave their consent to donation. Increasing age of the deceased was significantly positively associated with consent to donation (p = 0.006). Multivariable univariate analysis adjusting for age of deceased showed that relative type was strongly associated with consent (p<0.001), with mothers and fathers more likely to donate than siblings, and siblings more likely to donate than children and spouses. An indication of willingness to donate on a driving licence was strongly associated with consent (p<0.001).

CONCLUSIONS

Higher consent rates from older donors have implications for policies to maximise corneal procurement. The decision to donate on behalf of a deceased family member is complex and influenced by social context. Research should investigate individualised strategies to be used when seeking consent from particular categories of next of kin.