Retinoschisin gene therapy and natural history in the Rs1h-KO mouse: long-term rescue from retinal degeneration

PURPOSE: The authors characterized the natural history of a retinoschisin gene knockout (Rs1h-KO) mouse model and evaluated the long-term effects of retinal rescue after AAV(2/2)-CMV-Rs1h gene delivery. METHODS: Full-field scotopic electroretinograms (ERGs) were recorded from 44 male hemizygous Rs1h-KO and 44 male wild-type (WT) C57BL/6J mice at six ages between 1 and 16 months. Retinal morphometry included outer segment layer (OSL) width, photoreceptor cell count, and grading of schisis cavity severity. One eye each of seven Rs1h-KO mice at age 14 days was injected with AAV(2/2)-CMV-Rs1h, and retinal histology and ERG findings at 14 months were analyzed. RESULTS: The outer nuclear layer (ONL) of 1-month-old Rs1h-KO mice was disorganized but had nearly normal cell counts. The OSL was thinned, rod outer segments were misaligned, and abundant schisis cavities spanned the inner nuclear and outer plexiform layers in all retinas. ERG a- and b-wave amplitudes at this age were reduced by 33% and 50%, respectively. ERG and ONL cell numbers decreased further between 1 and 16 months, with unequal changes in the a- and b-waves with age. The a-wave reduction correlated well with the steady decline in ONL cell number, whereas a rapid decline in the b-wave and a (b/a-wave) ratio less than in WT were associated with increasing severity of schisis cavities at young ages. At 4 months, the cavities were maximal, but they coalesced and disappeared at older ages. The (b/a-wave) ratio was inversely correlated with cavity severity across all ages (r = -0.74; P < 0.0001; n = 22). Considerable heterogeneity was observed at each age in the ERG amplitudes and retinal morphology. Mice injected with AAV-Rs1h at 14 days showed considerable structural and functional rescue at age 14 months, including improved rod outer and inner segment integrity, less photoreceptor cell loss, and larger ERG amplitudes compared with untreated fellow eyes. CONCLUSIONS: The ERG of the Rs1h-KO mouse at early ages reflects disruption of photoreceptor and second-order neuron function. In mid to late ages, the ERG decline reflects primarily photoreceptor degeneration. The Rs1h-KO mouse is consistent with human clinical X-linked juvenile retinoschisis (XLRS) in showing schisis cavities, which affect primarily the b-wave, the regression of schisis cavities at older ages, and a considerable range in phenotypic severity across individuals. This mouse model also indicates the critical roll of RS-protein in photoreceptor survival consistent with decreased a-waves in some patients with XLRS. Long-term rescue of retinal morphology and function by AAV-Rs1h gene transfer may provide a basis for considering intervention in the homologous human XLRS condition.     

Juvenile X-Linked Retinoschisis with Normal Scotopic b-Wave in the Electroretinogram at an Early Stage of the Disease

Purpose: To report four cases of genetically verified juvenile X-linked retinoschisis (XLRS) with normal scotopic b-waves in full-field ERG, including one patient with a novel mutation (W50X) in the RS1gene. Methods: Four XLRS patients from different families were examined with regard to visual acuity, kinetic perimetry, fundus photography, full-field ERG, and OCT. Two of these patients were also examined with multifocal-ERG (mfERG). Mutations in the RS1gene were identified by sequence analysis. Results: The full-field ERG presented normal b-wave amplitudes on scotopic white-light stimulation. OCT and mfERG presented macular schisis and macular dysfunction. Genetic analysis revealed a deletion of exon 1 and the promotor region in one patient and mutations giving rise to the amino acid substitutions R209C and W96R in two others. The fourth patient carried a novel mutation in exon 3 of the RS1 gene (nt 149 G→A), causing the introduction of a stop codon after amino acid 49 in the RS protein. Conclusion: Four young males with XLRS did not present with reduction in the scotopic b-wave amplitude on full-field ERG, which is otherwise often considered to be characteristic of the disease. Full-field ERG and molecular genetic analysis of the RS1gene still remain the most important diagnostic tools for this retinal disorder, although the OCT can be a valuable complement in order to make the diagnosis at an early stage.     

Mutations of the XLRS1 gene cause abnormalities of photoreceptor as well as inner retinal responses of the ERG

Intensity-series rod and cone ERGs were recorded in 19 patients with XLRS and 26 control eyes. All patients were examined by one ophthalmologist and diagnosed on the basis of fundus appearance and evidence of the disease in other males in the same family. Mutations in the XLRS1 gene have been identified in 15 of the patients. Dark-adapted ERGs were significantly different from controls for all test conditions and for both a-wave and b-wave responses. Abnormalities were detectable in all patients but there was considerable variation in the severity of abnormality. One third of the patients had the dark-adapted `negative-wave' response typically associated with inner retinal disorder, but about one third showed only mild depression of the b-wave while the remainder had abnormally low a-waves in addition to depressed b-waves. Light-adapted responses were also affected and both a-wave and b-wave responses differed significantly from controls, but the `negative-wave' response was not seen in any patient. The severity of the ERG abnormality did not correlate with the classification of fundus appearance or patient age suggesting that retinal function is relatively stable throughout life. The severity of ERG abnormalities did not correlate with the type of mutation and responses could differ between affected males within the same family. These results indicate considerable heterogeneity of ERG response without clinical, age or genetic correlate. The abnormal a-wave responses indicate that photoreceptor as well as inner retinal layer function may be affected in XLRS, at least in some patients. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of photoreceptor function and inner retinal activity in juvenile X-linked retinoschisis

Thirteen retinoschisis males with genotyped XLRS1 gene mutations were examined by electroretinogram (ERG) techniques to determine photoreceptor involvement and ON-pathway and OFF-pathway sites of dysfunction. Parameters R(max) and logS determined by fitting the mathematical model of the activation phase of phototransduction to the scotopic and photopic a-wave responses, were not significantly different from normal. However, the XLRS photopic a-wave amplitudes were significantly lower than normal across all intensities, consistent with defective signaling in the OFF pathway. Long flash (150 ms) ON-OFF photopic responses showed reduced b-wave amplitude but normal d-wave amplitude, giving a reduced b/d ratio of <1.32 Hz photopic flicker ERG fundamental frequency responses showed reduced amplitude and delayed phase, consistent with abnormal signaling by both the ON- and OFF-pathway components. These results indicate that the XLRS1 protein appears not to affect photoreceptor function directly for most XLRS males, and that ERG signaling abnormalities occur in both the ON- and OFF-pathway components that originate in the proximal retina.     

Caveolar and non-Caveolar Caveolin-1 in ocular homeostasis and disease

Caveolae, specialized plasma membrane invaginations present in most cell types, play important roles in multiple cellular processes including cell signaling, lipid uptake and metabolism, endocytosis and mechanotransduction. They are found in almost all cell types but most abundant in endothelial cells, adipocytes and fibroblasts. Caveolin-1 (Cav1), the signature structural protein of caveolae was the first protein associated with caveolae, and in association with Cavin1/PTRF is required for caveolae formation. Genetic ablation of either Cav1 or Cavin1/PTRF downregulates expression of the other resulting in loss of caveolae. Studies using Cav1-deficient mouse models have implicated caveolae with human diseases such as cardiomyopathies, lipodystrophies, diabetes and muscular dystrophies. While caveolins and caveolae are extensively studied in extra-ocular settings, their contributions to ocular function and disease pathogenesis are just beginning to be appreciated. Several putative caveolin/caveolae functions are relevant to the eye and Cav1 is highly expressed in retinal vascular and choroidal endothelium, Müller glia, the retinal pigment epithelium (RPE), and the Schlemm's canal endothelium and trabecular meshwork cells. Variants at the CAV1/2 gene locus are associated with risk of primary open angle glaucoma and the high risk HTRA1 variant for age-related macular degeneration is thought to exert its effect through regulation of Cav1 expression. Caveolins also play important roles in modulating retinal neuroinflammation and blood retinal barrier permeability. In this article, we describe the current state of caveolin/caveolae research in the context of ocular function and pathophysiology. Finally, we discuss new evidence showing that retinal Cav1 exists and functions outside caveolae.     

X连锁遗传性视网膜劈裂症的分子遗传学与治疗研究进展

X连锁遗传性视网膜劈裂症(XLRS,OMIM#312700)是一种较少见的X连锁隐性遗传病,主要累及双侧视网膜,造成神经纤维层和神经节细胞层之间的劈裂,患者具有典型的车轮状中心凹劈裂和视网膜电图b/a比值下降的特征性电生理改变,是由于XLRS1基因发生突变而导致的一种遗传性眼底疾病.就XLRS的发病机制、动物实验和临床治疗的研究进展进行综述.     

Reduced synaptic vesicle density and aberrant synaptic localization caused by a splice site mutation in the Rs1h gene

X-linked retinoschisis (XLRS) is a common form of inherited macular degeneration caused by mutations in the RS1 gene. Whereas the role of RS1 has been implicated in the synaptic structure as well as layer organization in the retina, the pathological effect of a defective RS1 gene on the synaptic interaction between photoreceptor cells and second-order neurons has not been thoroughly investigated. In this study, we perform a detailed characterization of the retinal synaptic phenotypes caused by a splice site mutation in the murine RS1 homolog (Rs1h(tmgc1)). Electron microscopic analysis showed that presynaptic terminals of photoreceptor cells contain a lower areal density of synaptic vesicles in the Rs1h(tmgc1) retina. Examination of the synaptic interactions in the outer plexiform layer also revealed ectopic localization of photoreceptor cell presynaptic markers and elongation of neurites from postsynaptic neurons (bipolar and horizontal cells), which are observed in other mouse models with defective photoreceptor cell molecules. Consistent with these synaptic abnormalities, ERG analysis of young Rs1h(tmgc1) mice revealed attenuation of the b-wave with preservation of the a-wave. These results demonstrate that RS1H has functional significance in the morphology and function of the synapse between photoreceptors and second-order neurons. A developmental study from postnatal day (P) 15 through P19 showed that synaptic interactions form normally, and structural abnormalities occur after completion of synaptic formation suggesting that RS1H is important for the maintenance of this synaptic interaction. Thus, Rs1h(tmgc1) mice may serve as a new genetic model for human XLRS and other synaptic disorders.     

Advances in understanding the molecular structure of retinoschisin while questions remain of biological function

Retinoschisin (RS1) is a secreted protein that is essential for maintaining integrity of the retina. Numerous mutations in RS1 cause X-linked retinoschisis (XLRS), a progressive degeneration of the retina that leads to vision loss in young males. A key manifestation of XLRS is the formation of cavities (cysts) in the retina and separation of the layers (schisis), disrupting synaptic transmission. There are currently no approved treatments for patients with XLRS. Strategies using adeno-associated viral (AAV) vectors to deliver functional copies of RS1 as a form of gene augmentation therapy, are under clinical evaluation. To improve therapeutic strategies for treating XLRS, it is critical to better understand the secretion of RS1 and its molecular function. Immunofluorescence and immunoelectron microscopy show that RS1 is located on the surfaces of the photoreceptor inner segments and bipolar cells. Sequence homology indicates a discoidin domain fold, similar to many other proteins with demonstrated adhesion functions. Recent structural studies revealed the tertiary structure of RS1 as two back-to-back octameric rings, each cross-linked by disulfides. The observation of higher order structures in vitro suggests the formation of an adhesive matrix spanning the distance between cells (∼100 nm). Several studies indicated that RS1 readily binds to other proteins such as the sodium-potassium ATPase (NaK-ATPase) and extracellular matrix proteins. Alternatively, RS1 may influence fluid regulation via interaction with membrane proteins such as the NaK-ATPase, largely inferred from the use of carbonic anhydrase inhibitors to shrink the typical intra-retinal cysts in XLRS. We discuss these models in light of RS1 structure and address the difficulty in understanding the function of RS1.     

Juvenile X-linked retinoschisis with normal scotopic b-wave in the electroretinogram at an early stage of the disease

PURPOSE: To report four cases of genetically verified juvenile X-linked retinoschisis (XLRS) with normal scotopic b-waves in full-field ERG, including one patient with a novel mutation (W50X) in the RS1 gene. METHODS: Four XLRS patients from different families were examined with regard to visual acuity, kinetic perimetry, fundus photography, full-field ERG, and OCT. Two of these patients were also examined with multifocal-ERG (mfERG). Mutations in the RS1 gene were identified by sequence analysis. RESULTS: The full-field ERG presented normal b-wave amplitudes on scotopic white-light stimulation. OCT and mfERG presented macular schisis and macular dysfunction. Genetic analysis revealed a deletion of exon 1 and the promotor region in one patient and mutations giving rise to the amino acid substitutions R209C and W96R in two others. The fourth patient carried a novel mutation in exon 3 of the RS1 gene (nt 149 G-->A), causing the introduction of a stop codon after amino acid 49 in the RS protein. CONCLUSION: Four young males with XLRS did not present with reduction in the scotopic b-wave amplitude on full-field ERG, which is otherwise often considered to be characteristic of the disease. Full-field ERG and molecular genetic analysis of the RS1 gene still remain the most important diagnostic tools for this retinal disorder, although the OCT can be a valuable complement in order to make the diagnosis at an early stage.     

A comparison of ERG abnormalities in XLRS and XLCSNB

Dark and light adapted ERGs were recorded in 19 patients with XLRS and in 15 patients with CSNB. Patients were assigned to clinical groups after identification of mutations in the RS1 (16 patients), NYX (11 patients) and CACNA1F (4 patients) genes causing XLRS, 'complete' CSNB and 'incomplete' CSNB, respectively. ERG responses were compared with those of 26 healthy volunteers. Rod responses were most severely affected in patients in the NYX group but a rod-generated b-wave could be identified in the majority of patients in this group. Rod responses were less severely affected in the CACNA1F and RS1 groups and ERGs did not differ significantly between these two groups. Cone reponses were largely unaffected in the NYX group but were abnormal in the RS1 and especially CACNA1F groups. The ERG results suggest that the RS1 and CACNA1F gene products have comparable functional consequences and that all three genes may affect multiple retinal sites.     

先天性视网膜劈裂症基因突变型与临床表现型的关系

背景研究表明,导致先天性视网膜劈裂症（XLRS）的原因是RS1基因突变,XLRS的不同临床表现型与不同的基因突变类型有关,但基因型与表现型的关系仍不十分清楚。目的研究12个中国人XLRS家系及检测到的11种XLRS!基因突变与临床表现型的关系。方法对12个XLRS家系的28例男性患者（其余3例已死亡）及女性携带者和正常对照者分别进行详细的眼科检查,包括视力、屈光度、裂隙灯及眼底检查,部分患者行全视野视网膜电图（ERG）、眼底血管造影、光学相干断层扫描（OCT）及A／B型超声检查。采用聚合酶链反应（PCR）和单链构象多态性（SSCP）分析,对XLRSl基因突变进行筛查,并对发现异常泳带的PCR产物进行DNA测序,以明确突变位点及突变类型。结果12个家系的28例男性患者中27例有典型的黄斑及视网膜劈裂表现,ERG检查可见b波振幅下降,b／a波比值倒置。12个家系中检出11种不同的XLRSl致病基因突变,其中有4种新发现的基因突变,即：位于外显子1的移码突变（L9CfsX20）;位于外显子5的Aspl45His,Argl56Gly和Trp163X突变,并新发现1种非疾病相关多态性（NSP）,即位于外显子6的576C—T（Pr0192Pro）改变。同时发现位于外显子1的移码突变（22de／T）,外显子1与内含子1剪接位点突变（IVS1＋2TtoC）和Argl02Gln,Arg209His,Arg213Gln突变家系的患者,临床表现为严重型XLRS。结论XLRS1基因突变是导致中国人先天性视网膜劈裂的原因,XLRS的严重临床表现与基因突变的类型及突变位点具有一定的相关性。     

Müller cells and astrocytes in tractional macular disorders

Tractional deformations of the fovea mainly arise from an anomalous posterior vitreous detachment and contraction of epiretinal membranes, and also occur in eyes with cystoid macular edema or high myopia. Traction to the fovea may cause partial- and full-thickness macular defects. Partial-thickness defects are foveal pseudocysts, macular pseudoholes, and tractional, degenerative, and outer lamellar holes. The morphology of the foveal defects can be partly explained by the shape of Müller cells and the location of tissue layer interfaces of low mechanical stability. Because Müller cells and astrocytes provide the structural scaffold of the fovea, they are active players in mediating tractional alterations of the fovea, in protecting the fovea from such alterations, and in the regeneration of the foveal structure. Tractional and degenerative lamellar holes are characterized by a disruption of the Müller cell cone in the foveola. After detachment or disruption of the cone, Müller cells of the foveal walls support the structural stability of the foveal center. After tractional elevation of the inner layers of the foveal walls, possibly resulting in foveoschisis, Müller cells transmit tractional forces from the inner to the outer retina leading to central photoreceptor layer defects and a detachment of the neuroretina from the retinal pigment epithelium. This mechanism plays a role in the widening of outer lameller and full-thickness macular holes, and contributes to visual impairment in eyes with macular disorders caused by conractile epiretinal membranes. Müller cells of the foveal walls may seal holes in the outer fovea and mediate the regeneration of the fovea after closure of full-thickness holes. The latter is mediated by the formation of temporary glial scars whereas persistent glial scars impede regular foveal regeneration. Further research is required to improve our understanding of the roles of glial cells in the pathogenesis and healing of tractional macular disorders.     

Factores asociados al desprendimiento de retina pseudofáquico: seguimiento a largo plazo en una población colombiana

ObjectiveTo identify associated factors with the appearance of pseudophakic retinal detachment in patients with history of cataract surgery.MethodsRetrospective case–control study of 802 eyes of 783 patients with history of cataract surgery. Cases were patients with pseudophakic retinal detachment (n = 258 eyes), while controls were patients with cataract surgery who did not developed retinal detachment during a 10-year follow-up period (n = 544 eyes).ResultsAge at cataract surgery among cases was lower than in the control group (57 ± 13 vs. 67 ± 14 years old, respectively; P < .0001). Age at retinal detachment was 59 ± 13 years old (range 6–88) and the time between the cataract surgery and the retinal detachment had a median of 2 years (interquartile range 1–4) with a range of 1 month to 14 years. Associated factors for pseudophakic retinal detachment were younger age (< 50 years: adjusted odds ratio [aOR] = 18.03, 95% confidence interval [95% CI] = 5.92–54.87; 50–59 years: aOR = 10.09, 95% CI = 3.37–30.23; and 60–69 years: aOR = 5.48, 95% CI = 1.88–15.93), male sex (aOR = 3.71, 95% CI = 2.54–5.44), anterior vitrectomy (aOR = 3.26, 95% CI = 1.16–9.16), history of retinal detachment in the fellow eye (aOR = 6.95, 95% CI = 3.15–15.31), and intraoperative complications during cataract extraction (aOR = 7.45, 95% CI = 3.54–15.69).ConclusionsThis is the first report of associated factors with pseudophakic retinal detachment in a Colombian population. Surgical complications, sex, and age were found to be associated with retinal detachment. Patients should be aware of these potential risks to make informed decisions about their eye health.     

X-linked juvenile retinoschisis: clinical diagnosis, genetic analysis, and molecular mechanisms

X-linked juvenile retinoschisis (XLRS, MIM 312700) is a common early onset macular degeneration in males characterized by mild to severe loss in visual acuity, splitting of retinal layers, and a reduction in the b-wave of the electroretinogram (ERG). The RS1 gene (MIM 300839) associated with the disease encodes retinoschisin, a 224 amino acid protein containing a discoidin domain as the major structural unit, an N-terminal cleavable signal sequence, and regions responsible for subunit oligomerization. Retinoschisin is secreted from retinal cells as a disulphide-linked homo-octameric complex which binds to the surface of photoreceptors and bipolar cells to help maintain the integrity of the retina. Over 190 disease-causing mutations in the RS1 gene are known with most mutations occurring as non-synonymous changes in the discoidin domain. Cell expression studies have shown that disease-associated missense mutations in the discoidin domain cause severe protein misfolding and retention in the endoplasmic reticulum, mutations in the signal sequence result in aberrant protein synthesis, and mutations in regions flanking the discoidin domain cause defective disulphide-linked subunit assembly, all of which produce a non-functional protein. Knockout mice deficient in retinoschisin have been generated and shown to display most of the characteristic features found in XLRS patients. Recombinant adeno-associated virus (rAAV) mediated delivery of the normal RS1 gene to the retina of young knockout mice result in long-term retinoschisin expression and rescue of retinal structure and function providing a 'proof of concept' that gene therapy may be an effective treatment for XLRS.     

Genotypic and phenotypic spectrum of X-linked retinoschisis in Australia

BACKGROUND: X-linked retinoschisis (XLRS), an X-linked recessive inherited degenerative retinopathy, is characterized by splitting in the nerve fibre layer and is caused by alterations in the RS1 gene. The aim of the present study was to review both the phenotypic features of XLRS and the mutation spectrum of the RS1 gene in an Australian cohort. METHODS: Patients were recruited from ophthalmic and paediatric hospitals as well as private ophthalmic clinics across Australia. A cohort of 18 presumably unrelated families was identified. Twenty-two affected patients underwent clinical examination. Following DNA extraction all six exons of the RS1 gene were sequenced. RESULTS: The median age at diagnosis was 8 years (range 1-43 years); the median age at review was 14 years (range 5-63 years). The median best-corrected visual acuity upon review was 6/24 (range 6/6-1/36). Typical foveal schisis was found in 90.1% eyes examined (39/43) while peripheral schisis was present in 30% of eyes (13/43). The scotopic blue b-wave amplitude ranged between 2% and 82% of the mean normal amplitude. Five novel mutations (61G-->T, Gly21X; 103C-->T, Gln35X; 327-329del, Cys110del; 527T-->C, Phe176Ser; 573Gdel, Pro192fs) and six previously identified missense mutations (304C-->T, Arg102Trp; 305G-->A, Arg102Gln; 336G-->C, Trp112Cys; 418G-->A, Gln140Arg; 598C-->T, Arg200Cys; 625C-->T, Arg209Cys) were found. The mutations present in codons 21 and 102 were each identified in two presumably unrelated pedigrees. One previously described point deletion (416Adel) was identified. Two pedigrees contained affected individuals where exons 2 or 3, respectively, were unable to be amplified, indicating the likely presence of a significant deletion. No mutation was found in the RS1 gene in two affected individuals from different pedigrees. CONCLUSION: Population genetic studies of XLRS have not previously been conducted in Australia. The phenotype associated with these mutations varied. The identification of each pedigree's specific mutation allows future determination of female carrier status for genetic counselling purposes. Further study into the refinement of the XLRS phenotype as well as the degree of intrafamilial phenotypic variation is required.     

Pole to pole

An otherwise asymptomatic 67-year-old man presented to his ophthalmologist complaining of acute painless “dark area on the right.” Visual acuity was preserved, and a single cotton-wool spot was noted in each retina. An inferior right quadrantanopia was evident on automated visual fields, and computerized tomography of the brain confirmed a left occipital stroke. Acute phase markers were elevated, and temporal artery biopsy was consistent with a diagnosis of giant cell arteritis. Isolated retinal cotton wool spots, even in the absence of systemic signs and symptoms, may be suggestive of giant cell arteritis.     

Capsaicin-induced pain sensitivity in short tear break-up time dry eye

PurposeTo evaluate transient receptor potential vanilloid 1 (TRPV1)-mediated pain sensitivity in patients with short tear break-up time (TBUT) dry eye (DE) by using the capsaicin stimulus test.MethodsThis prospective cross-sectional comparative study included 22 eyes of 22 patients with short TBUT DE and 11 eyes of 11 non-DE control subjects. Patients were divided into two groups based on response to standard DE treatments: 10 non-responders (intractable DE) and 12 responders (responsive DE). Mechanical touch (M-touch) and mechanical pain (M-pain) were measured using a Cochet-Bonnet esthesiometer. Capsaicin-induced pain (C-pain) and C-pain duration (C-pain DT) were measured using a capsaicin stimulus test. Psychological distress was also assessed.ResultsM-touch sensitivity was similar among all three groups. M-pain sensitivity was higher in the responsive DE group than in the intractable DE and control groups (P < .001). C-pain sensitivity was lower (P < .001) in the intractable DE group than in the responsive DE and control groups, and C-pain DT was shorter (P = .006) in the intractable DE group than in the responsive DE group. Psychological distress was higher in the intractable DE group than in the control group (P < .001).ConclusionsPatients with intractable short TBUT DE were less sensitive to the effects of capsaicin than patients with responsive short TBUT DE and controls. Altered neural activation may contribute to the development of DE symptoms in the short TBUT DE subjects. The capsaicin stimulus test may be used to better understand pain sensitivity in short TBUT DE patients.     

Investigation of factors associated with ABCB5-positive limbal stem cell isolation yields from human donors

PurposeTo identify factors associated with isolation yields of ATP-binding cassette (ABC) superfamily member B5 (ABCB5)-positive limbal stem cells (LSCs) from human cadaveric donor eyes.MethodsWhole eye globes were obtained from the Saving Sight eye bank, Kansas City, MO and the CorneaGen eye bank, Seattle, WA. ABCB5-positive LSCs were sorted by flow cytometry upon anti-ABCB5 monoclonal antibody staining within one week after donor death. The yields of live limbal epithelial cells in their entirety and of isolated pure ABCB5-positive LSC subsets were correlated with variables contained in the eye donors’ medical information.ResultsThe mean isolation yield of live limbal epithelial cells and ABCB5-positive LSCs per donor eye was (340,000 ± 160,000 and 2,608 ± 1,842 respectively, mean ± SD). Stepwise regression analysis showed that cardiac disease-related death was the strongest negative predictor of the ABCB5-positive LSC isolation yield (p = 0.01). While we observed a trend for an age-related decline in the yield of ABCB5-positive LSCs, a statistically significant association could not be established (2% decrease/year, p = 0.11). Additionally, despite a trend for decreased isolation yields of total live limbal epithelial cells isolated from single donors with a longer time between death and tissue processing (p = 0.04), this did not affect the yields of purified ABCB5-positive LSC, which was independent of increasing time between death and tissue processing (p = 0.50).ConclusionsOur study identifies cardiac disease-related death as a donor variable significantly associated with lower ABCB5-positive LSC isolation yields.