Sten Raeder

Safety and Efficacy of Epithelium-On Corneal Collagen Cross-Linking Using a Multifactorial Approach to Achieve Proper Stromal Riboflavin Saturation

Purpose. To evaluate the efficacy and safety of epithelium-on corneal collagen cross-linking (CXL) using a multifactorial approach to achieve proper stromal riboflavin saturation. Methods. This non-randomized retrospective study comprised 61 eyes with progressive keratoconus treated with epithelium-on CXL. Chemical epithelial penetration enhancement (benzalkonium chloride-containing local medication and hypotonic riboflavin solution), mechanical disruption of the superficial epithelium, and prolongation of the riboflavin-induction time until verification of stromal saturation were used before the UVA irradiation. Uncorrected and corrected distance visual acuity (UDVA, CDVA), refraction, corneal topography, and aberrometry were evaluated at baseline and at 1, 3, 6, and 12 months postoperative. Results. At 12-month, UDVA and CDVA improved significantly. None of the eyes lost lines of CDVA, while 27.4% of the eyes gained 2 or more lines. Mean spherical equivalent decreased by 0.74 D, and mean cylindrical reduction was 1.15 D. Irregularity index and asymmetry from Scheimpflug-based topography and Max-K at the location of cone from Placido-based topography showed a significant decrease. Higher-order-aberration data demonstrated a slight reduction in odd-order aberrations S 3, 5,7 (P = 0.04). Postoperative pain without other complications was recorded. Conclusion. Epithelium-on CXL with our novel protocol appeared to be safe and effective in the treatment of progressive keratoconus.

A novel method for preserving cultured limbal epithelial cells

Aim: To investigate organ culture preservation of cultured limbal epithelial cells in order to enhance the availability of tissue-engineered epithelia that are used to treat patients with limbal stem cell deficiency. Methods: Limbal epithelial cells were cultured for 3 weeks on intact amniotic membrane fastened to a polyester membrane carrier. The cultured epithelia were stored for 1 week at 23°C in organ culture medium. The preserved epithelia were then examined using a colorimetric cell viability assay, light microscopy and immunohistochemistry. Results: The viability of the preserved epithelia was 84% (20%), and no statistically significant difference was found compared with non-preserved epithelia. In general, the cell borders were maintained, the nuclei showed no sign of degeneration, and the original layered structure was preserved. Mild intercellular oedema was occasionally observed. Expression of p63, K19 and vimentin was maintained. Conclusions: Cultured limbal epithelial cells can be preserved in organ culture medium for 1 week at room temperature, while maintaining the original layered structure and undifferentiated phenotype.

Sterility control and long-term eye-bank storage of cultured human limbal epithelial cells for transplantation

Background/aims: To assess sterility of cultured human limbal epithelial cells (HLEC) and to investigate the viability, morphology and phenotype of cultured HLEC following 2 and 3 weeks of organ culture storage. Methods: HLEC cultured on amniotic membranes were stored in organ culture medium in a closed container at 23°C. Sterility of storage media was tested using a Bactec 9240 blood culture instrument (Becton Dickinson, Maryland) for incubation and periodic reading. Viability was analysed by calcein-acetoxymethyl ester/ethidium homodimer-1 assay, morphology by light microscopy and cellular phenotype by immunohistochemistry. Results: No microbial contamination was observed after 1 week’s storage. Viability of cultured HLEC was 87.9 (SD 6.4)% and 52.7 (13.1)% after 2 and 3 weeks of storage, respectively, compared with 98.8 (2.6)% before storage (p<0.001). The multilayered structure was preserved in 70% of cultures following 2 weeks of storage but lost after 3 weeks. A less differentiated phenotype was maintained. Conclusion: This study is the first to verify the sterility of HLEC cultures prior to transplantation. Although a slight decrease in viability was observed following 2 weeks of storage, the HLEC sheets remain acceptable, whereas 3 week’s storage was unsatisfactory.

Comparison of the Histology, Gene Expression Profile, and Phenotype of Cultured Human Limbal Epithelial Cells from Different Limbal Regions

PURPOSE To investigate whether human limbal epithelial cells (HLECs) derived from various regions of the limbus exhibit differences in gene expression and epithelial characteristics. METHODS HLECs were derived from explants taken from the superior, nasal, inferior, and temporal limbus and cultured for 21 days. Whole genome transcript profiling was performed with a gene microarray. The microarray results were validated by using RT-PCR. Epithelial morphology was studied with light microscopy and transmission electron microscopy, and phenotype was evaluated by immunohistochemistry. RESULTS Epithelial outgrowth was present in most cultures of superior origin (88%) in contrast to cultures of temporal origin (38%). The epithelial thickness and number of cell layers were significantly greater in cultures of superior origin than in cultures from inferior and temporal areas. TRIM36, OSR2, and RHOU, which are involved in morphogenesis, were significantly differentially expressed in the superior region, compared with the other regions. Proposed limbal stem cell, progenitor, and differentiation markers were not differentially expressed. The uniform gene expression of ocular surface markers correlated with homogeneous immunostaining of corresponding protein markers in HLEC cultures from all regions, demonstrating an undifferentiated phenotype (p63(+), DeltaNp63alpha(+), ABCG2(+), K19(+), vimentin(+), integrin beta1(+), nestin(-), K3(-), K5(+), and E-cadherin(+)). CONCLUSIONS No major transcriptional or phenotypic differences were observed in cultured HLECs derived from different regions of the limbus. However, explants of superior origin demonstrated the highest outgrowth success rate and generated epithelia with greater epithelial thickness and number of cell layers, which may prove useful for transplantation purposes.

Short‐term postoperative non‐supine positioning versus strict face‐down positioning in macular hole surgery

Purpose:  The purpose of this study was to compare the efficacy of short‐term non‐supine positioning (NSP) and strict face‐down positioning (FDP) in the repair of macular hole (MH).

Effect of Biopsy Location and Size on Proliferative Capacity of Ex Vivo Expanded Conjunctival Tissue

PURPOSE To evaluate the effect of location and size of biopsy on phenotype and proliferative capacity of cultured rat conjunctival epithelial cells. METHODS Pieces of conjunctiva were used from six areas: superior and inferior areas of bulbus, fornix, and tarsus of male Sprague-Dawley rats (n = 6). Explants were grown in RPMI 1640 with 10% fetal bovine serum on coverslips for 8 days or assayed for colony-forming efficiency (n = 9). Analysis included immunofluorescence microscopy and outgrowth measurements with ImageJ software. The Mann-Whitney test and Spearmans rank-order correlation test were used. RESULTS Superior (23.9 ± 2.9-fold growth) and inferior (22.4 ± 1.2-fold growth) forniceal tissues yielded significantly more outgrowth with respect to explant size than superior bulbar (13.4 ± 1.9-fold growth; P < 0.05 and P < 0.01, respectively), inferior bulbar (13.6 ± 1.6-fold growth; P = 0.01 and P < 0.01, respectively), and inferior tarsal tissues (14.0 ± 1.3-fold growth; P = 0.01). Outgrowth size correlated positively with explant size (r(s) = 0.54; P < 0.001), whereas explant size correlated negatively with fold growth (r(s) = 0.36; P < 0.001). Superior forniceal cells displayed higher colony-forming efficiency (3.6% ± 0.9%) than superior bulbar (1.1% ± 0.3%; P < 0.05) and inferior bulbar cells (1.6% ± 0.8%; P < 0.05). Percentage of p63+ and PCNA+ cells correlated positively with explant and outgrowth size. CONCLUSIONS Small forniceal conjunctival explants grow the most effectively; however, for transplantation purposes, the loss of p63+ and PCNA+ cells with small explants must be considered.

The impact of de-epithelialization of the amniotic membrane matrix on morphology of cultured human limbal epithelial cells subject to eye bank storage.

Purpose: To investigate whether human limbal epithelial cells (HLEC) that have been cultured on intact or de-epithelialized amniotic membranes (AMs) demonstrate differences in morphology after 1 week of eye bank storage. Methods: HLEC were cultured from limbal explants for 3 weeks on intact AM and AM deprived of the amniotic epithelial cells by incubation with 0.02% ethylene diamine tetra acetic acid followed by mechanical scraping. The HLEC cultures were stored for 1 week in a closed container in a serum-based medium at 23°C. The surface morphology was assessed using scanning electron microscopy, and a quantitative comparison of desmosome and hemidesmosome numbers was performed using transmission electron microscopy. Results: Although most superficial epithelial cells were closely attached to each other, with tightly opposed cell junctions and distinct cell borders, there was evidence of some cell separation in HLEC that had been cultured on intact and denuded AM after 1 week of storage. In both experimental groups, the epithelia were well stratified, consisting of basal column-shaped cells, suprabasal cuboid wing cells, and flat squamous superficial cells, but dilated intercellular spaces were observed. The total number of desmosomes per micron was 1.39 ± 0.77 in HLEC cultured on intact AM versus 0.98 ± 0.45 in HLEC expanded on denuded AM (P = 0.76). The total number of hemidesmosomes per micron in HLEC cultured on intact AM and denuded AM was 0.87 ± 0.34 and 0.78 ± 0.31, respectively (P = 0.70). Conclusions: Denuding of AM does not improve the structural integrity of cultured HLEC after eye bank storage.

The culture of limbal epithelial cells.

The transplantation of cultured limbal epithelial cells (LEC) has since its first application in 1997 emerged as a promising technique for treating limbal stem cell deficiency. The culture methods hitherto used vary with respect to preparation of the harvested tissue, choice of culture medium, culture time, culture substrates, and supplementary techniques. In this chapter, we describe a procedure for establishing human LEC cultures using a feeder-free explant culture technique with human amniotic membrane (AM) as the culture substrate.

Biopsy harvesting site and distance from the explant affect conjunctival epithelial phenotype ex vivo

The purpose of the study was to investigate if the number of goblet cells expanded ex vivo from a conjunctival explant is affected by the biopsy harvesting site on the conjunctiva and the distance from the explant. Conjunctival explants from six regions: superior and inferior bulbus, fornix, and tarsus of male Sprague-Dawley rats were grown in RPMI 1640 with 10% fetal bovine serum on coverslips for eight days. Histochemical and immunofluorescent staining of goblet (CK-7/UEA-1/MUC5AC), stratified squamous, non-goblet (CK-4), proliferating (PCNA) and progenitor (ABCG2) cells were analyzed by epifluorescence and laser confocal microscopy. Outgrowth was measured with NIH ImageJ. For statistical analysis the Mann-Whitney test and Spearmans rank-order correlation test were used. Cultures from superior and inferior fornix contained the most goblet cells as indicated by the presence of CK-7+, UEA-1+ and MUC5AC+ cells. Superior and inferior forniceal cultures displayed 60.8% ± 9.2% and 64.7% ± 6.7% CK-7+ cells, respectively, compared to the superior tarsal (26.6% ± 8.4%; P < 0.05), superior bulbar (31.0% ± 4.0%; P < 0.05), inferior bulbar (38.5% ± 9.3%; P < 0.05) and inferior tarsal cultures (27.7% ± 8.3%; P < 0.05). While 28.4% ± 6.3% of CK-7+ goblet cells co-labeled with PCNA, only 7.4% ± 1.6% of UEA-1+ goblet cells did (P < 0.01). CK-7+ goblet cells were located at a lower concentration close to the explant (39.8% ± 3.1%) compared to near the leading edge (58.2% ± 4.5%; P < 0.05). Both markers for goblet cell secretory product (UEA-1 and MUC5AC), however, displayed the opposite pattern with a higher percentage of positive cells close to the explant than near the leading edge (P < 0.05). The percentage of CK-4+ cells was higher near the explant compared to near the leading edge (P < 0.01). The percentage of CK-7+ goblet cells in the cultures did not correlate with the outgrowth size (r(s) = -0.086; P = 0.435). The percentage of UEA-1+ goblet cells correlated negatively with outgrowth size (r(s) = -0.347; P < 0.01), whereas the percentage of CK-4+ cells correlated positively with the outgrowth size (r(s) = 0.473; P < 0.05). We conclude that forniceal explants yield the highest number of goblet cells ex vivo and thereby seem to be optimal for goblet cell transplantation. We also suggest that CK-7+/UEA-1- cells represent highly proliferative immature goblet cells. These cells could be important during conjunctival migration as they are mostly located close to the leading edge and their density does not decrease with increasing outgrowth size.

Serum-Free and Xenobiotic-Free Preservation of Cultured Human Limbal Epithelial Cells

Aim/Purpose of the Study To develop a one-week storage method, without serum and xenobiotics, that would maintain cell viability, morphology, and phenotype of cultured human limbal epithelial sheets. Materials and Methods Human limbal explants were cultured on intact human amniotic membranes for two weeks. The sheets were stored in a hermetically sealed container at 23°C in either a serum-free medium with selected animal serum-derived compounds (Quantum 286) or a xenobiotic-free medium (Minimal Essential Medium) for 4 and 7 days. Stored and non-stored cultures were analyzed for cell viability, amniotic membrane and epithelial sheet thickness, and a panel of immunohistochemical markers for immature cells (ΔNp63α, p63, Bmi-1, C/EBP∂, ABCG2 and K19), differentiated cells (K3 and Cx43), proliferation (PCNA), and apoptosis (Caspase-3). Results The cell viability of the cultures was 98 ± 1% and remained high after storage. Mean central thickness of non-stored limbal epithelial sheets was 23 ± 3 μm, and no substantial loss of cells was observed after storage. The non-stored epithelial sheets expressed a predominantly immature phenotype with ΔNp63α positivity of more than 3% in 9 of 13 cultures. After storage, the expression of ABCG2 and C/EBP∂ was reduced for the 7 day Quantum 286-storage group; (P = 0.04), and Bmi-1 was reduced after 4 day Quantum 286-storage; (P = 0.02). No other markers varied significantly. The expression of differentiation markers was unrelated to the thickness of the epithelia and amniotic membrane, apart from ABCG2, which correlated negatively with thickness of limbal epithelia (R = -0.69, P = 0.01) and ΔNp63α, which correlated negatively with amniotic membrane thickness (R = -0.59, P = 0.03). Conclusion Limbal epithelial cells cultured from explants on amniotic membrane can be stored at 23°C in both serum-free and xenobiotic-free media, with sustained cell viability, ultrastructure, and ΔNp63α-positivity after both 4 and 7 days.