Bispecific VEGF-A and Angiopoietin-2 Antagonist RO-101 Preclinical Efficacy in Model of Neovascular Eye Disease.

Objective: To investigate preclinical data regarding the efficacy and biocompatibility of a bispecific protein, RO-101, with effects on VEGF-A and angiopoietin-2 (Ang-2) for use in retinal diseases. Design: Experimental study. Subjects: Brown Norway rats and New Zealand White Cross rabbits. Methods: Preclinical study data of RO-101 in terms of target-specific enzyme-linked immunosorbent assay binding affinity to VEGF-A and Ang-2, vitreous half-life, inhibition of target-receptor interaction, laser choroidal neovascular membrane animal model, human umbilical vein endothelial cell migration, and biocompatibility was obtained. Where applicable, study data were compared with other anti-VEGF agents. Main Outcome Measures: Binding affinity, half-life, biocompatibility, and efficacy of RO-101. Neovascularization prevention by RO-101. Results: RO-101 demonstrated a strong binding affinity for VEGF-A and Ang-2 and in vitro was able to inhibit binding to the receptor with higher affinity than faricimab. The half-life of RO-101 is comparable to or longer than current VEGF inhibitors used in retinal disease. RO-101 was found to be biocompatible with retinal tissue in Brown Norway rats. RO-101 was as effective or more effective than current anti-VEGF therapeutics in causing regression of neovascular growth in vivo. Conclusions: RO-101 is a promising candidate for use in retinal diseases. In preclinical models, RO-101 demonstrated similar or higher regression of neovascular growth to current anti-VEGF therapeutics with comparable or longer half-life. It also demonstrates a strong binding affinity for VEGF-A and Ang-2. It also was shown to be biocompatible with retinal tissue in animal studies, indicating potential compatibility for use in humans. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

NO EFFECT OF REAL-WORLD UNIVERSAL FACE MASKING ON POST-INTRAVITREAL INJECTION ENDOPHTHALMITIS RATE AT A SINGLE TERTIARY ACADEMIC CENTER.

PURPOSE: To determine whether universal masking during COVID-19 altered rate and outcomes of postinjection endophthalmitis. METHODS: Retrospective, single-site, comparative, cohort study. Eyes diagnosed with endophthalmitis within 4 weeks of intravitreal injection at the University of Michigan from August 1, 2012, to November 15, 2022, were identified. Cases were considered "masking" between March 15, 2020, and November 15, 2022. Endophthalmitis rate, visual acuity, and microbial spectrum were investigated. RESULTS: There were 20 postinjection endophthalmitis cases out of 72,194 injections (0.028%; one in 3,571 injections) premasking and 10 of 38,962 with universal masking (0.026%; one in 3,846 injections; odds ratio 0.9; 95% [confidence interval]: 0.4-2.0). Referral from the community was unchanged with 32 cases referred premasking (0.35 cases/month) and 10 cases with masking (0.31 cases/month). Presenting mean the logarithm of the minimum angle of resolution visual acuity with masking of all postinjection endophthalmitis cases trended worse (2.35 ± 0.40) compared with premasking (2.09 ± 0.48; P = 0.05) with light perception visual acuity more common with masking (31.6% vs. 10.9%, P = 0.06). There was no delay in time from procedure to initial treatment ( P = 0.36), no difference in the rate of initial treatment with tap and inject (T/I), and similar positive-culture rates ( P = 0.77) between the cohorts. Visual acuity after 30 days of follow-up was clinically unchanged (∼20/500 vs. 20/400; P = 0.59). CONCLUSION: Universal masking had no effect on postinjection endophthalmitis rate or on the rate of culture-positive cases. Although presenting visual acuity appeared worse with masking, this was not statistically significant, and current treatment paradigms resulted in similar visual outcomes.

Retinal Detachments after Open-Globe Injury: Risk Factors and Outcomes.

PURPOSE: To identify risk factors for retinal detachment (RD) after open-globe injury (OGI) and evaluate outcomes of RD repair after OGI. DESIGN: Case-control study. PARTICIPANTS: Overall, 769 patients presented with 786 OGIs, which were surgically managed with ≥ 30 days of follow-up. Of the 786 eyes, 223 developed RD, the other 551 served as controls, and RD status of 12 eyes was unknown. METHODS: A retrospective chart review was performed of all OGIs presented to the University of Michigan between 2000 and 2022. Multivariable regression identified risk factors for RD after OGI and predictors of poor vision after RD repair. Kaplan-Meier analysis estimated time from OGI to RD. MAIN OUTCOME MEASURE: Predictors of visual outcome after RD repair after OGI. RESULTS: After OGI, 223 (28.4%) of 786 eyes were diagnosed with RD, with > 73% diagnosed within a month. Predictors of RD include posterior injury (zone II vs. I odds ratio [OR], 1.60 [95% confidence interval {CI}, 1.04-2.46]; P = 0.0331; zone III vs. I OR, 2.29 [1.53-3.41]; P < 0.0001), vitreous hemorrhage (OR, 2.29 [1.54-3.1]; P < 0.0001), and presenting acuity worse than count fingers (CFs) (OR, 2.65 [1.69 - 4.16]; P < 0.0001). Retinal detachment repair took place in 142 of 223 eyes. The mean logarithm of minimal angle of resolution visual acuity (VA) improved from 2.3 ± 0.8 to 1.7 ± 0.9 after RD repair at 6-month follow-up, with 51.2% of eyes achieving CF or better vision. Single surgery anatomic success rate was 69.7% and final anatomic success was 88%. Predictors of vision worse than CF include history of ocular surgery (OR, 0.32 [0.11-0.94]; P = 0.039), proliferative vitreoretinopathy (PVR; OR, 0.39 [0.16 - 0.92]; P = 0.032), aphakia (OR, 0.25 [0.08 - 0.77]; P = 0.016), and redetachment (OR, 0.26 [0.1 - 0.63]; P = 0.003). CONCLUSIONS: Most RD occur within the first month after OGI. Patients with posterior injuries, vitreous hemorrhage, or poor presenting VA were more likely to develop RD after OGI. Anatomic success was achieved in the majority, as was final VA of CF vision or better. History of ocular surgery, PVR at time of repair, aphakia, and redetachment were risk factors for a poor outcome. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

RHEGMATOGENOUS RETINAL DETACHMENT AFTER INITIATION OF PILOCARPINE HYDROCHLORIDE OPHTHALMIC SOLUTION 1.25% FOR TREATMENT OF PRESBYOPIA.

BACKGROUND/PURPOSE: Retinal detachment has previously been reported in association with topical miotic use for the treatment of glaucoma. Pilocarpine hydrochloride 1.25% was recently approved by the Food and Drug Administration for the treatment of presbyopia, with no reports of associated retinal detachments in the clinical trial data. METHODS: Case report. RESULTS: Two novel cases of unilateral retinal detachment occurring within 10 days of the initiation of pilocarpine 1.25% for the treatment of presbyopia were described. The patients were pseudophakic men in their 60s or 70s with preexisting retinal detachment risk factors, such as high myopia, lattice degeneration, and prior retinal detachment. Both affected eyes were treated with pars plana vitrectomy and gas endotamponade with an uncomplicated postoperative course. CONCLUSION: Retinal detachment may be associated with the use of pilocarpine 1.25%. Caution should be used when considering prescribing this medication in patients with preexisting retinal abnormality.

An Evaluation of the Repeatability of Visual Function Following Surgical Repair of Macula-Off Rhegmatogenous Retinal Detachment.

Purpose: To evaluate the reliability and reproducibility of visual function assessments for patients with macula-off rhegmatogenous retinal detachment (RRD). Methods: This prospective study included patients with unilateral macula-off RRD of <10-day duration successfully treated with a single, uncomplicated surgery at least 1 year following repair. Visual function assessments were performed at time of enrollment and 1 month later. Testing included Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), low-contrast visual acuity (VA) 2.5% and 5%, contrast sensitivity assessment with Mars and Gabor patches, reading speed (acuity, speed, and critical print size), color vision testing (protan, deutan, and tritan), and microperimetry. Spectral-domain ocular coherence tomography (SD-OCT) was performed. Paired t-statistics were used to compare values between visits and between the study and fellow eyes. Results: Fourteen patients (9 male, 5 female) with a mean age of 69 years at time of surgery were evaluated. Correlation coefficients across the two visits were highest for ETDRS BCVA (0.97), tritan color vision testing (0.96), and low-contrast VA 5% (0.96), while the average t-statistic was largest for low-luminance deficit (4.2), ETDRS BCVA (4.1), and reading speed critical print size (3.7). ETDRS BCVA did not correlate with SD-OCT findings. Conclusions: ETDRS BCVA can be considered a highly reliable and reproducible outcome measure. LLVA, protan color discrimination, contrast sensitivity, and reading speed may be useful secondary outcome measures. Translational Relevance: This study provides guidance on the selection of visual function outcome measures for clinical trials of patients with macula-off RRD.

Clinical Characteristics and Visual Outcomes of Acute Syphilitic Posterior Placoid Chorioretinopathy.

PURPOSE: To evaluate presenting features and visual outcomes in eyes with acute syphilitic posterior placoid chorioretinopathy (ASPPC). DESIGN: Retrospective cohort study. SUBJECTS: A total of 24 eyes of 17 adult patients with ASPPC. METHODS: Chart review of patients with ASPPC who presented to the University of Michigan W. K. Kellogg Eye Center between January 1, 2012, and November 4, 2022. Demographic and clinical information, fundus photographs, fundus autofluorescence, and spectral-domain-OCT (SD-OCT) findings were reviewed. MAIN OUTCOME MEASURES: Clinical characteristics and visual acuity (VA) on presentation and follow-up examination. RESULTS: The median age was 46 (interquartile range [IQR], 38-51) years. At presentation, 20 (83.3%) eyes had subjectively decreased vision, with a median initial VA of 0.54 (IQR, 0.35-1.00) logarithm of the minimum angle of resolution (logMAR); at 45 days, median logMAR VA was 0.096 (IQR, 0.02-0.17). Initial VA was positively associated with posterior pole-sparing lesions (coefficient estimate [CE], -0.75; 95% confidence interval [CI], -1.38 to -0.12); P = 0.03), and negatively associated with ellipsoid zone (EZ) disruption (CE, 0.72; 95% CI, 0.03-1.42; P = 0.04), subfoveal EZ disruption (CE, 0.62; 95% CI, 0.02-1.23; P = 0.046), and initial hyperreflective foci on SD-OCT (CE, 0.66; 95% CI, 0.09-1.23; P = 0.03). Female eyes were more likely (hazard ratio [HR], 3.36; 95% CI, 1.07-10.6; P = 0.04), and eyes with optic nerve abnormality were less likely (HR, 0.34; 95% CI, 0.12-0.96; P = 0.04), to achieve a VA ≥ 20/40 (logMAR, 0.30). CONCLUSIONS: This study of patients with ASPPC showed that symptomatic eyes had an improvement from a median VA of 20/69 on presentation to a median VA of 20/25 at 45 days. Female sex and absence of optic nerve involvement were associated with higher probability of achieving ≥ 20/40. These findings provide refined guidance for counseling patients who present with decreased vision due to ASPPC. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Risk Factors for Enucleation Following Open Globe Injury: A 17-Year Experience.

Purpose: At the time of open globe injury (OGI), it may be difficult for clinicians to predict which eyes are at highest risk for requiring enucleation. We performed a 17-year retrospective cohort study to report outcomes and risk factors for enucleation following open globe injuryto better aid clinicians counseling patients at OGI diagnosis. Methods: A retrospective cohort study of all patients who presented to the University of Michigan with open globe injury (OGI) and were surgically managed between January 2000 and July 2017 was conducted. At least 30 days of follow-up was required. All eyes that ultimately underwent enucleation following OGI were identified and their clinical course analyzed. The main outcome measured was the rate of enucleation after OGI. Results: There were 587 eyes meeting inclusion criteria. The mean patient age was 40.75 ± 25.1 (range 1-91). 441/585 (75.4%) patients were male. Average follow-up time was 1029.9 ± 1285.9 days. 116/587 eyes (19.8%) required enucleation after OGI, with 81.9% undergoing enucleation less than 30 days from injury. In enucleated eyes, the mean presenting logMAR vision was 2.91 ± 0.47 (Snellen equivalent between hand motion and light perception). The most common mechanism of injury requiring enucleation was globe rupture, 89/116 (76.7%), with 14/116 (12.1%) penetrating injuries and 13/116 (11.2%) perforating injuries. The mean age of patients that underwent enucleation was 45.6 ± 22.5 (range 3-91). Conclusion: Open globe injuries are often visually devastating and a significant number of cases ultimately require enucleation. Despite emergent closure within 24 hours, 19.8% of eyes managed for OGI at our institution required eventual enucleation. 81.2% of these eyes required enucleation within 30 days of injury. Wound length greater than 10 mm, uveal prolapse, higher zone of injury, IOFB, and RAPD were identified as risk factors that predict future need for enucleation.

Endophthalmitis, Visual Outcomes, and Management Strategies in Eyes with Intraocular Foreign Bodies.

Purpose: Ocular trauma with intraocular foreign body (IOFB) can have devastating visual consequences. Management and antimicrobial strategies remain variable due to the infrequency and heterogeneity of presentation. Our goal was to identify risk factors for endophthalmitis and poor visual outcomes in cases of IOFB and investigate management strategies. Patients and Methods: A retrospective chart review was conducted in 88 eyes of 88 patients suffering traumatic injury with IOFB at the University of Michigan between January 2000 and December 2019. Medical records were reviewed to characterize the injuries and IOFBs as well as how clinical presentation and treatment modalities were associated with outcomes. Results: Delayed presentation (P=0.016) and organic IOFB (P=0.044) were associated with development of endophthalmitis. Retinal detachment (P=0.012), wound length greater than 5 mm (P=0.041), and poor presenting visual acuity (P=0.003) correlated with poor final visual outcome. Antibiotic prophylaxis was given to all patients, though agents and routes of delivery varied. Endophthalmitis developed in 4.9% of the eyes after initial management, with primary and secondary removal of posterior segment IOFBs associated with similar rates of endophthalmitis (P=1.000). Conclusion: Poor presenting visual acuity and severity of injury, as measured by large wound and retinal detachment, correlate with poor visual outcome. Prompt globe closure and antimicrobial prophylaxis are critical for infection prevention. In cases where IOFB removal and globe closure cannot be performed concurrently, primary globe closure with aggressive antibiotic prophylaxis offers a reasonable alternative to prevent endophthalmitis.

The Clinical Characteristics of Noninfectious Occlusive Retinal Vasculitis.

PURPOSE: To characterize the clinical features of occlusive retinal vasculitis (ORV). DESIGN: Retrospective case series. PARTICIPANTS: Forty-two patients with ORV. METHODS: A retrospective chart review identified all patients with ORV seen at the University of Colorado uveitis service between January 2013 and April 2020. All included patients demonstrated noninfectious uveitis and evidence of vascular occlusion in the presence of retinal vascular inflammation on widefield fluorescein angiography. MAIN OUTCOME MEASURES: Demographic data, visual acuity, clinical findings, and fluorescein angiography findings. RESULTS: We identified 73 eyes from 42 patients (15 men, 27 women) with ORV. Thirty-one of 42 patients had bilateral disease. Most eyes (54/73) showed mixed arteriolar and venous vasculitis compared with primarily arteriolar (6/73) or venous (15/73) vasculitis. Thirteen of 42 patients had an underlying systemic condition, most commonly granulomatosis with polyangiitis; however, bilaterality was not associated with a systemic condition. Retinal nonperfusion was present equally in zone 2 (28/73) and zone 3 (28/73) compared with zone 1 (16/73). Retinal or iris neovascularization was present in 25 of 73 eyes. Eighteen of 42 patients required more than 1 immunosuppressive medication (average, 1.33) to prevent progressive vascular occlusive disease. CONCLUSIONS: Occlusive retinal vasculitis is a heterogeneous entity with significant risk of visual impairment. Systemic disease was more prevalent in this specific cohort compared with cohorts from prior studies of retinal vasculitis.

Fibrotic cataract as a sign of posterior capsule violation post vitrectomy.

PURPOSE: To report fibrotic cataract as a sign of posterior capsule violation post vitrectomy. OBSERVATIONS: A 16 year old female presented to our retina clinic after multiple prior vitrectomies at an outside hospital for traumatic retinal detachment. On presentation, it was noted that she still had a silicone oil inside the eye, and a dense, fibrotic cataract limiting the posterior pole view. The decision was made to pursue cataract phacoemulsification plus silicone oil removal. We utilized the Zepto capsulotomy system given the white cataract. After gentle bimanual irrigation and aspiration of the cataract, it was discovered there were two small, round, posterior capsule defects with fibrosis around these holes that extended anteriorly, involving the capsular fornix and anterior capsule. This was confirmed intraoperatively on heads-up OCT. A three-piece intraocular lens was placed into the capsular bag, but given the contracted capsular fornix, the IOL was decentered inferonasally, so it was repositioned in the sulcus with good centration. CONCLUSIONS: It is known that pars plana vitrectomy leads to accelerated cataract formation postoperatively. This case report is the first to our knowledge that describes a fibrotic cataract as a sign of posterior capsular violation. IMPORTANCE: We demonstrate that presence of fibrotic cataract post vitrectomy should raise suspicion for capsular violation and should prompt further discussion with the patient regarding appropriate surgical planning and expectations.

Risk Factors for Endophthalmitis Following Open Globe Injuries: A 17-Year Analysis.

BACKGROUND/AIMS: To determine the rate of endophthalmitis and assess risk factors for development of endophthalmitis following open globe injury (OGI). METHODS: A retrospective chart review of all patients treated for OGI at the University of Michigan from January 2000 to July 2017 was conducted. Exclusion criteria included intravitreal injection or intraocular surgery in the 30 days prior to injury or less than 30 days of follow-up. A total of 586 out of 993 open globe injuries were included in the study. The main outcome measure was the rate of endophthalmitis. RESULTS: In this study, 25/586 eyes (4.3%) had endophthalmitis. Of these, 12/25 eyes (48.0%) presented with endophthalmitis and 13/25 eyes (52.0%) developed endophthalmitis after globe closure. Multivariate analysis identified time to globe repair (OR 4.5, CI 1.9-10.7, p = 0.0008), zone I injury (OR 3.6, CI 1.1-11.0, p = 0.0282), and need for additional surgery (OR 5.5, CI 1.5-19.7, p = 0.0092) as factors associated with increased risk of developing endophthalmitis. Subconjunctival antibiotic injection at the time of globe closure (OR 0.3, CI 0.1-0.7, p = 0.0036) was associated with decreased risk of developing endophthalmitis. CONCLUSION: Prompt globe closure and subconjunctival antibiotics may reduce the risk of endophthalmitis in OGI. Furthermore, our practice of a one-time dose of systemic prophylactic antibiotics, and intravitreal antibiotics if intraocular foreign body (IOFB) removal is delayed, was not found to increase the rate of endophthalmitis.

Rapamycin Prolongs the Survival of Corneal Epithelial Cells in Culture.

Rapamycin has previously been shown to have anti-aging effects in cells and organisms. These studies were undertaken to investigate the effects of rapamycin on primary human corneal epithelial cells in vitro. Cell growth and viability were evaluated by bright field microscopy. Cell proliferation and cycle were evaluated by flow cytometry. The expression of differentiation markers was evaluated by quantitative PCR and Western blot. Senescence was evaluated by senescence-associated ß-Galactosidase staining and by Western blot analysis of p16. Apoptosis was evaluated by a TUNEL assay. The results demonstrated that primary HCEC treated with rapamycin had lower proliferation but considerably longer survival in vitro. Rapamycin-treated cells maintained a higher capacity to proliferate after removal of rapamycin and expressed more keratin 14, N-Cadherin, DeltaNp63 and ABCG2, and less keratin 12, consistent with their less differentiated state. Rapamycin treated cells demonstrated less senescence by X-ß-Gal SA staining and by lower expression of p16. Apoptosis was also lower in the rapamycin treated cells. These results indicate that rapamycin treatment of HCEC prevents the loss of corneal epithelial stem/progenitor cells to replicative senescence and apoptosis. Rapamycin may be a useful additive for ex vivo expansion of corneal epithelial cells.

Current and Upcoming Therapies for Ocular Surface Chemical Injuries.

Chemical injuries frequently result in vision loss, disfigurement, and challenging ocular surface complications. Acute interventions are directed at decreasing the extent of the injury, suppressing inflammation, and promoting ocular surface re-epithelialization. Chronically, management involves controlling inflammation along with rehabilitation and reconstruction of the ocular surface. Future therapies aimed at inhibiting neovascularization and promoting ocular surface regeneration should provide more effective treatment options for the management of ocular chemical injuries.

Full-length nucleotide sequences of 30 common SLC44A2 alleles encoding human neutrophil antigen-3.

BACKGROUND: Human neutrophil antigen-3a (HNA-3a) alloantibodies can cause severe transfusion-related acute lung injury. The frequencies of the single-nucleotide polymorphisms (SNPs) indicative of the two clinically relevant HNA-3a/b antigens are known in many populations. In this study, we determined the full-length nucleotide sequence of common SLC44A2 alleles encoding the choline transporter-like protein-2 that harbors HNA-3a/b antigens. STUDY DESIGN AND METHODS: A method was devised to determine the full-length coding sequence (CDS) and adjacent intron sequences from genomic DNA by eight polymerase chain reaction amplifications covering all 22 SLC44A2 exons. Samples from 200 African American, 96 Caucasian, two Hispanic, and four Asian blood donors were analyzed. We developed a decision tree to determine alleles (confirmed haplotypes) from the genotype data. RESULTS: A total of 10 SNPs were detected in the SLC44A2 CDS. The noncoding sequences harbored an additional 28 SNPs (one in the 5'-untranslated region [UTR]; 23 in the introns; and four in the 3'-UTR). No SNP indicative of a nonfunctional allele was detected. The nucleotide sequences for 30 SLC44A2 alleles (haplotypes) were confirmed. There may be 66 haplotypes among the 604 chromosomes screened. CONCLUSIONS: We found 38 SNPs, including one novel SNP, in 8192 nucleotides covering the CDS of the SLC44A2 gene among 302 blood donors. Population frequencies of these SNPs were established for African Americans and Caucasians. Because alleles encoding HNA-3b are more common than non-functional SLC44A2 alleles, we confirmed our previous postulate that African American donors are less likely to form HNA-3a antibodies compared to Caucasians.

Stability of limbal stem cell deficiency after mechanical and thermal injuries in mice.

We studied the reproducibility and stability of limbal stem cell deficiency (LSCD) in mice following controlled injuries to the corneal and limbal epithelia. In one method, corneal and limbal epithelia were entirely removed with a 0.5 mm metal burr. In the other, limbus to limbus epithelial removal with the burr was followed by thermal injury to the limbus. These two methods were compared with a previously published one. Unwounded corneas were used as control. The corneas were examined monthly for three months by slit lamp with fluorescein staining. Immunofluorescence staining for cytokeratin 12 and 8 on corneal wholemount and cross sections were performed to determine the phenotype of the epithelium. Mechanical shaving of the epithelium, with or without thermal injury, resulted in a reproducible state of LSCD marked by superficial neovascularization, reduce of keratin 12 expression and presence of goblet cells on the cornea. The phenotype was stable in 100% of the eyes up to at least three months. Thermal injury produced a more severe phenotype with more significant stromal opacification. These corneal injury models may be useful for studying the mechanisms leading to limbal stem cell deficiency.

Frequencies of SLC44A2 alleles encoding human neutrophil antigen-3 variants in the African American population.

BACKGROUND: The human neutrophil antigen-3 (HNA-3) epitopes reside on the choline transporter-like protein-2 (CTL2). A single-nucleotide substitution (461G>A; Arg154Gln) on the CTL2 gene (SLC44A2) defines the allele SLC44A2*1, which expresses HNA-3a, and SLC44A2*2, which expresses HNA-3b; an additional substitution (457C>T; Leu153Phe) in SLC44A2*1:2 may impact genotyping systems. People who only express HNA-3b may develop anti-HNA-3a. These alloantibodies have been linked to severe transfusion-related acute lung injury, which may be a reason to screen blood donors for SLC44A2*2 homozygosity. For Caucasian and Asian populations, SLC44A2 allele frequencies are known. Our primary objective was to determine the SLC44A2 allele frequencies in the African American population. STUDY DESIGN AND METHODS: Purified DNA from 334 individuals (202 male, 132 female; 241 African American, 93 Caucasian) was collected. Two real-time polymerase chain reaction assays were developed to genotype all samples; results were confirmed by nucleotide sequencing. RESULTS: In 241 African American donors, the allele frequency of SLC44A2*1 was 93% (85%-<100%; 95% confidence intervals, Poisson distribution) while SLC44A2*2 was 7% (5%-10%). In 93 Caucasian donors, the allele frequency of SLC44A2*1 was 83% (71%-98%) and SLC44A2*2 was 17% (11%-24%), matching previously reported data for Caucasians but differing from African Americans (p < 0.001, Fisher's exact test). CONCLUSIONS: This study describes the allele frequencies of the three known HNA-3 variants in an African American population. We found that African Americans have a significantly lower probability of possessing the SLC44A2*2 allele and may thus be less likely to form the clinically relevant anti-HNA-3a.

Red blood cell preservation by droplet freezing with polyvinylpyrrolidone or sucrose-dextrose and by bulk freezing with glycerol.

BACKGROUND: Red blood cell (RBC) preservation is essential to transfusion medicine. Many blood group reference laboratories need a method to preserve rare blood samples for serologic testing at a later date. This study offers a comparison of three common cryoprotective agents and protocols used today: bulk preservation with glycerol and droplet freezing with sucrose-dextrose (S+D) or polyvinylpyrrolidone (PVP). STUDY DESIGN AND METHODS: Human blood from 14 volunteers was collected and frozen at set intervals over 2 weeks with PVP, S+D, or glycerol. The frozen RBCs were later thawed and the percentage of surviving RBCs was determined. Detailed protocols and an instructional video are supplied. RESULTS: Over a 2-week period, RBCs preserved with glycerol and thawed with a widely used protocol showed a recovery of 41 ± 16% (mean ± standard deviation) while those thawed with a modified glycerol protocol showed a recovery of 76 ± 8%. RBCs preserved by droplet freezing with S+D showed a recovery of 56 ± 11% while those preserved by droplet freezing with PVP showed a recovery of 85 ± 6%. Recovery values were similar with ethylenediaminetetraacetic acid or heparin anticoagulants, differing freezing rates, and varying droplet volumes. CONCLUSION: Droplet freezing with PVP offered the greatest recovery. While bulk freezing with glycerol can also be effective, droplet freezing may be a more convenient method overall. It requires less effort to thaw, needs much less storage room, and allows blood group laboratories to be frugal with thawing rare samples.