Light scattering measurements in electron-beam sterilized corneas stored in recombinant human serum albumin.

Irradiated corneal tissues have been used for a variety of ophthalmic procedures including glaucoma drainage device covers and lamellar grafts. The maintenance of corneal clarity is important, as light obstructions resulting from processing or long-term storage of irradiated corneas may negatively affect vision and postoperative cosmesis. It has been reported that corneal tissues can be preserved in human serum albumin (HSA), however, the clarity of corneas after long-term storage in HSA has not been well described. Furthermore, the use of donor-pooled serum increases the risk for transmission of blood-borne diseases and may induce an immune response in the recipient. Here, we examined changes in corneal clarity due to electron-beam (e-beam) irradiation and storage in a recombinant human serum albumin (rHSA). Dark-field microscopy was employed to examine the light scattering effects of fresh and irradiated corneas. Compared to measurements taken prior to tissue preparation and e-beam treatment, irradiated corneas showed an average 2.6% increase in light scattering (P = 0.002). Irradiated corneas stored in rHSA at room-temperature for 20 months showed an average increase of 11.6% light scattering compared to fresh corneas (P â‰ª 0.01), but did not negatively affect the visualization of printed text, and were deemed suitable for transplant use. Therefore, the slight increase in cornea light scattering, and resulting reduction in corneal clarity, after e-beam treatment and long-term storage in rHSA may not be clinically significant. These results suggest that e-beam sterilized corneal grafts may be used as an alternative to fresh tissue for certain ophthalmic applications.

Characterization of cryopreserved primary human corneal endothelial cells cultured in human serum-supplemented media.

PURPOSE: To compare cryopreserved human corneal endothelial cells (HCECs) grown in human serum-supplemented media (HS-SM) with cryopreserved HCECs grown in fetal bovine serum-supplemented media (FBS-SM). METHODS: Three pairs of human corneas from donors aged 8, 28, and 31 years were obtained from the eye bank. From each pair, one cornea was used to start a HCEC culture using HS-SM; the other cornea was grown in FBS-SM. On reaching confluence, the six cell populations were frozen using 10% dimethyl sulfoxidecontaining medium. Thawed cells grown in HS-SM were compared with those grown in FBS-SM with respect to morphology, growth curves, immunohistochemistry, real time-reverse transcriptase polymerase chain reaction (RT-PCR) for endothelial cell markers, and detachment time. RESULTS: No difference in morphology was observed for cells grown in the two media before or after cryopreservation. By growth curves, cell counts after thawing were similar in both media, with a slight trend toward higher cell counts in FBS-SM. Cells grown in both the media demonstrated a similar expression of endothelial cell markers when assessed by immunohistochemistry, although HCEC marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM as assessed by RT-PCR. With FBS-SM, there was a tendency of longer detachment time and lower cell passages. CONCLUSIONS: HS-SM was similar to FBS-SM for cryopreservation of cultured HCECs as assessed by analysis of cell morphology, proliferation, and protein expression, although marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM. Detachment time was longer with FBS-SM and in lower passages.

Characterization of cryopreserved primary human corneal endothelial cells cultured in human serum-supplemented media / Caracterização de células endoteliais corneanas humanas primárias criopreservadas cultivadas em meio suplementado com soro humano

ABSTRACT Purpose: To compare cryopreserved human corneal endothelial cells (HCECs) grown in human serum-supplemented media (HS-SM) with cryopreserved HCECs grown in fetal bovine serum-supplemented media (FBS-SM). Methods: Three pairs of human corneas from donors aged 8, 28, and 31 years were obtained from the eye bank. From each pair, one cornea was used to start a HCEC culture using HS-SM; the other cornea was grown in FBS-SM. On reaching confluence, the six cell populations were frozen using 10% dimethyl sulfoxidecontaining medium. Thawed cells grown in HS-SM were compared with those grown in FBS-SM with respect to morphology, growth curves, immunohistochemistry, real time-reverse transcriptase polymerase chain reaction (RT-PCR) for endothelial cell markers, and detachment time. Results: No difference in morphology was observed for cells grown in the two media before or after cryopreservation. By growth curves, cell counts after thawing were similar in both media, with a slight trend toward higher cell counts in FBS-SM. Cells grown in both the media demonstrated a similar expression of endothelial cell markers when assessed by immunohistochemistry, although HCEC marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM as assessed by RT-PCR. With FBS-SM, there was a tendency of longer detachment time and lower cell passages. Conclusions: HS-SM was similar to FBS-SM for cryopreservation of cultured HCECs as assessed by analysis of cell morphology, proliferation, and protein expression, although marker gene expression was higher in cells grown in HS-SM than in those grown in FBS-SM. Detachment time was longer with FBS-SM and in lower passages.

RESUMO Objetivo: Comparar células endoteliais de córnea humana (HCECs) criopreservadas e cultivadas em meio suplementado com soro humano (HS-SM) com HCEC criopreservadas e cultivadas em meio suplementado com soro bovino fetal (FBS-SM). Métodos: Três pares de córneas humanas de doadores com 8, 28 e 31 anos de idade foram obtidos do banco de olhos e, de cada par, uma córnea foi utilizado para iniciar uma cultura com HS-SM e outra com FBS-SM. Ao atingir a confluência, as populações de células foram congeladas utilizando-se dimetil-sulfóxido 10% no respectivo meio de cultura. Após descongeladas, as células cultivadas em HS-SM foram comparados com as cultivadas em FBS-SM por meio de morfologia, curva de crescimento, imuno-histoquímica, reação em cadeia de Reação em cadeia da polimerase da transcrição reversa em tempo real (RT-PCR) para marcadores de células endoteliais e tempo de descolamento. Resultado: Não foram observadas diferenças morfológicas antes ou após a criopreservação. Curva de crescimento mostrou contagens celulares semelhantes em ambos os meios, com discreta tendência para um maior número em FBS-SM. As células cultivadas em ambos os meios mostraram expressão semelhante de marcadores celulares endoteliais quando avaliadas por imuno-histoquímica, embora a expressão genética de marcadores para HCEC tenha sido maior em HS-SM quando avaliado por RT-PCR. Houve uma tendência de maior tempo de descolamento com FBS-SM e passagens iniciais. Conclusões: HS-SM foi semelhante ao FBS-SM na criopreservação de HCEC cultivadas in vitro quando avaliadas por morfologia celular, proliferação celular e expressão proteica, embora a expressão genética de marcadores endoteliais tenha sido maior em células cultivadas em HS-SM quando comparadas a células cultivadas em FBS-SM. O tempo de descolamento foi maior quando utilizado FBS-SM e em passagens iniciais.

The S-stamp in Descemet Membrane Endothelial Keratoplasty Safely Eliminates Upside-down Graft Implantation.

PURPOSE: To present 6-month clinical outcomes from a series of 165 consecutive Descemet membrane endothelial keratoplasty (DMEK) procedures before and after the introduction of a novel stromal-sided S-stamp preparation technique that has decreased the incidence of iatrogenic primary graft failure by eliminating upside-down grafts. DESIGN: Retrospective nonrandomized comparative case series. PARTICIPANTS: We included 165 consecutive eyes that had undergone DMEK surgery for Fuchs' or pseudophakic bullous keratopathy. These cases were divided into 2 cohorts: the first cohort comprised 31 cases that used unstamped tissue before the S-stamp was introduced, and the second cohort comprised 133 cases after the S-stamp was incorporated into the standardized technique. A single unstamped DMEK case was performed after the introduction of the S-stamp for a total of 32 unstamped cases. METHODS: Donor materials were prepared at a single eye bank using a standardized technique, which subsequently incorporated the addition of a dry ink gentian violet S-stamp to the stromal side of Descemet membrane. All surgeries were performed at a single clinical site by 5 surgeons (2 attending surgeons and 3 fellows). Two of the 165 DMEK cases were performed for pseudophakic bullous keratopathy (2 cases, 1 in each cohort), and the remaining cases were for Fuchs' endothelial dystrophy. Primary outcome measures were assessed at 6 months and maintained in a prospective institutional review board-approved study. MAIN OUTCOME MEASURES: We analyzed the 6-month endothelial cell density, incidence of iatrogenic primary graft failure, upside-down graft implantation, and rebubble events. RESULTS: The S-stamp eliminated upside-down graft implantations (0/133 S-stamped vs 3/32 unstamped) and did not significantly alter 6-month endothelial cell loss (31±17% S-stamped vs 29±14% unstamped; P = 0.62) or frequency of rebubble (17/133 S-stamped vs 1/32 unstamped; P = 0.20). CONCLUSION: The incorporation of a stromal-sided S-stamp eliminates iatrogenic primary graft failure owing to upside-down implantation of DMEK grafts, without adversely affecting early postoperative complications or 6-month endothelial cell loss.

Quantification and Patterns of Endothelial Cell Loss Due to Eye Bank Preparation and Injector Method in Descemet Membrane Endothelial Keratoplasty Tissues.

PURPOSE: To evaluate endothelial cell damage after eye bank preparation and passage through 1 of 2 different injectors for Descemet membrane endothelial keratoplasty grafts. METHODS: Eighteen Descemet membrane endothelial keratoplasty grafts were prepared by Lions VisionGift with the standard partial prepeel technique and placement of an S-stamp for orientation. The grafts were randomly assigned to injection with either a glass-modified Jones tube injector (Gunther Weiss Scientific Glass) or a closed-system intraocular lens injector (Viscoject 2.2; Medicel). After injection, the grafts were stained with the vital fluorescent dye Calcein AM and digitally imaged. The percentage of cell loss was calculated by measuring the area of nonfluorescent pixels and dividing it by the total graft area pixels. RESULTS: Grafts injected using the modified Jones tube injector had an overall cell loss of 27% ± 5% [95% confidence interval, 21%-35%]. Grafts injected using the closed-system intraocular lens injector had a cell loss of 32% ± 8% (95% confidence interval, 21%-45%). This difference was not statistically significant (P = 0.3). Several damage patterns including damage due to S-stamp placement were observed, but they did not correlate with injector type. CONCLUSIONS: In this in vitro study, there was no difference in the cell loss associated with the injector method. Grafts in both groups sustained significant cell loss and displayed evidence of graft preparation and S-stamp placement. Improvement in graft preparation and injection methods may improve cell retention.

Stamping an S on DMEK Donor Tissue to Prevent Upside-Down Grafts: Laboratory Validation and Detailed Preparation Technique Description.

PURPOSE: To report endothelial cell loss (ECL) caused by a novel S-stamp preparation technique for Descemet membrane endothelial keratoplasty (DMEK). METHODS: Six cadaveric human corneas were prepared for DMEK transplantation using a single standardized technique, including the application of a dry ink gentian violet S-stamp to the stromal side of Descemet membrane. Endothelial cell death was evaluated and quantified using computerized analysis of vital dye staining. RESULTS: ECL caused by the S-stamp was 0.6% (range 0.1%-1.0%), which comprised less than one-tenth of the total ECL caused by our preparation of the DMEK graft from the start to finish, including recovery, prestripping, S-stamping, and trephination (13.7% total ECL, range 9.9%-17.6%). CONCLUSIONS: Our novel S-stamp donor tissue preparation technique is intuitive to learn and holds the promise of preventing iatrogenic primary graft failure due to upside-down grafts without causing unacceptable increases in ECL.

Eye Bank-Prepared Femtosecond Laser-Assisted Automated Descemet Membrane Endothelial Grafts.

PURPOSE: The aim of this study was to investigate the use of a femtosecond laser (FL) in the eye bank preparation of corneas for Descemet membrane (DM) automated endothelial keratoplasty (fDMAEK) and to compare endothelial cell death in graft preparations between fDMAEK, Descemet stripping endothelial keratoplasty (DSEK), and DM endothelial keratoplasty (DMEK). METHODS: Twenty cadaveric tissues were used to test the fDMAEK method. A 9.0-mm-diameter lamellar incision was made using the FL with a 6.0-mm perpendicular anterior ring cut that enabled a stromal rim by acting as a venting incision for bubble expansion. DM was pneumodissected off the central 6.0 mm of the tissue. The fDMAEK grafts were trephined and stained with a viability dye, calcein AM. The entire stained endothelial surface was digitally captured and the endothelial cell loss (ECL) was calculated using trainable segmentation software. For comparison, a series of 6 DSEK grafts and 8 DMEK grafts were created and analyzed. RESULTS: Six of 20 tissues (30%) were lost during fDMAEK preparation. In the 14 successful tissues, the average ECL was 30.4% [95% confidence interval (CI), 25.3-35.6] compared with 21.1% (95% CI, 13.2-28.9, P = 0.09) in the 6 DSEK grafts and 22.5% (95% CI, 18.0-27.0, P = 0.04) in the 8 DMEK grafts. CONCLUSIONS: FLs are useful in preparing DMAEK tissue at the eye bank and may promote predictable and precise big bubbles and stromal rims. The fDMAEK preparation success improved with experience and laser adjustments. In fDMAEK, the ECL is higher than was previously reported in DMEK and DSEK, likely due to greater tissue manipulation, although not significantly higher than DSEK controls.

Use of human serum for human corneal endothelial cell culture.

BACKGROUND/AIMS: To study human corneal endothelial cells (HCECs) cultured in vitro with human serum (HS) supplemented media (HS-SM) compared with HCEC cultured in fetal bovine serum (FBS) supplemented media (FBS-SM). METHODS: One cornea from a donor aged 21 years and a pair of corneas from a 16 year-old donor were obtained from the eye bank and used to create two different cell populations. At the first passage, the cell populations were equally divided and seeded in two different wells containing FBS-SM or HS-SM. In subsequent passages, HS-SM was compared with FBS-SM by morphology, growth curves, immunohistochemistry and real-time reverse-transcriptase PCR for endothelial cell markers. RESULTS: No difference in morphology could be seen in P2, P5 or in any other passages for cells grown in the two media. By growth curves, cell counts were similar in FBS-SM and HS-SM from days 1 to 5, with a trend towards higher cell counts in HS-SM at day 7. Cells grown in FBS-SM and HS-SM media showed similar expression of endothelial cell markers when assessed by immunohistochemistry and real-time reverse-transcriptase PCR. CONCLUSIONS: HS-SM was similar to FBS-SM for HCEC culture when assessed by cell morphology, proliferation and protein/gene expression.

Imaging and quantification of endothelial cell loss in eye bank prepared DMEK grafts using trainable segmentation software.

PURPOSE: To improve accuracy and efficiency in quantifying the endothelial cell loss (ECL) in eye bank preparation of corneal endothelial grafts. METHODS: Eight cadaveric corneas were subjected to Descemet Membrane Endothelial Keratoplasty (DMEK) preparation. The endothelial surfaces were stained with a viability stain, calcein AM dye (CAM) and then captured by a digital camera. The ECL rates were quantified in these images by three separate readers using trainable segmentation, a plug-in feature from the imaging software, Fiji. Images were also analyzed by Adobe Photoshop for comparison. Mean times required to process the images were measured between the two modalities. RESULTS: The mean ECL (with standard deviation) as analyzed by Fiji was 22.5% (6.5%) and Adobe was 18.7% (7.0%; p = 0.04). The mean time required to process the images through the two different imaging methods was 19.9 min (7.5) for Fiji and 23.4 min (12.9) for Adobe (p = 0.17). CONCLUSIONS: Establishing an accurate, efficient and reproducible means of quantifying ECL in graft preparation and surgical techniques can provide insight to the safety, long-term potential of the graft tissues as well as provide a quality control measure for eye banks and surgeons. Trainable segmentation in Fiji software using CAM is a novel approach to measuring ECL that captured a statistically significantly higher percentage of ECL comparable to Adobe and was more accurate in standardized testing. Interestingly, ECL as determined using both methods in eye bank-prepared DMEK grafts exceeded 18% on average.

Endothelial keratoplasty: the influence of insertion techniques and incision size on donor endothelial survival.

PURPOSE: To determine the acute endothelial cell damage from trephination and tissue insertion in endothelial keratoplasty (EK) surgery. The influence of insertion technique (forceps insertion vs "pull-through" insertion) of donor tissue and incision size (3 vs 5 mm length) was assessed. METHODS: Forty precut 8.-mm-diameter donor posterior buttons were used in this study. Thirty-five buttons were inserted through a limbal incision of either 3 or 5 mm length into the anterior chamber of cadaver eyes and then removed through an open sky technique without further trauma. Five buttons that were trephined but not inserted served as a control group. Vital dye staining and computer digitized planimetry were used to analyze the tissue and quantify the total damaged area over the entire endothelial surface. Five buttons for each of 7 insertion techniques were used. The 8 tissue groups evaluated were as follows: group 1: control group of trephination only, with no insertion; group 2: forceps with folded tissue through 5-mm incision; group 3: suture pull through of nonfolded tissue through a 5-mm incision; group 4: forceps pull through of Busin glide folded tissue through a 5-mm incision; group 5: forceps with folded tissue through a 3-mm incision; group 6: suture pull through with folded tissue through a 3-mm incision; group 7: suture pull through with nonfolded tissue through a 3-mm incision; and group 8: forceps pull through of Busin glide folded tissue through a 3-mm incision. RESULTS: The control group demonstrated 9% +/- 2% peripheral cell damage from simple trephination of the tissue but without insertion. In the 5-mm incision surgeries, forceps insertion (group 2) caused 18% +/- 3% loss, suture pull-through insertion (group 3) caused 18% +/- 2% loss, and Busin glide pull through (group 4) caused 20% +/- 5% loss. There were no significant differences in damage between any of the 5-mm incision group techniques (P > 0.99). In the 3-mm incision surgeries, forceps insertion (group 5) caused a 30% +/- 3% loss, pull through with folded tissue (group 6) caused 30% +/- 5% loss, pull through with nonfolded tissue (group 7) caused 56% +/- 4% loss, and Busin glide pull through (group 8) caused a 28%+/- 5% loss. There was no difference in damage among the 3-mm groups (P > 0.96), with the exception of group 7 where pulling the unfolded tissue through a 3-mm incision was significantly worse than all other techniques (P < 0.001). There was significantly greater cell area damage in the 3-mm groups (36%) than in the 5-mm groups (19%) (P <0.001). Large patterns of striae with cell loss were seen in the 3-mm groups emanating from the peripheral traction site, regardless of whether the traction to pull the tissue through the incision and into the chamber was generated by a suture or cross-chamber forceps. Direct forceps insertion caused circular patterns of injury at the tip compression site regardless of incision size, but this damage was multiplied and exacerbated by insertion through a smaller incision. CONCLUSIONS: Smaller size (3 mm) incisions for EK surgery result in greater acute endothelial area damage than larger size (5 mm) incisions. Pull-through insertion techniques through a 5-mm incision seem equivalent in the amount of induced area damage to that of forceps insertion. Compressive injury from the incision appeared less when the tissue was folded than when not folded. Insertion with any technique through a 3-mm incision resulted in larger areas of endothelial damage. All these iatrogenic death zones outside the central endothelial area would be missed clinically by standard early specular microscopy after EK surgery.

An easy and inexpensive method for quantitative analysis of endothelial damage by using vital dye staining and Adobe Photoshop software.

PURPOSE: We developed a simple, practical, and inexpensive technique to analyze areas of endothelial cell loss and/or damage over the entire corneal area after vital dye staining by using a readily available, off-the-shelf, consumer software program, Adobe Photoshop. The purpose of this article is to convey a method of quantifying areas of cell loss and/or damage. METHODS: Descemet-stripping automated endothelial keratoplasty corneal transplant surgery was performed by using 5 precut corneas on a human cadaver eye. Corneas were removed and stained with trypan blue and alizarin red S and subsequently photographed. Quantitative assessment of endothelial damage was performed by using Adobe Photoshop 7.0 software. RESULTS: The average difference for cell area damage for analyses performed by 1 observer twice was 1.41%. For analyses performed by 2 observers, the average difference was 1.71%. Three masked observers were 100% successful in matching the randomized stained corneas to their randomized processed Adobe images. CONCLUSIONS: Vital dye staining of corneal endothelial cells can be combined with Adobe Photoshop software to yield a quantitative assessment of areas of acute endothelial cell loss and/or damage. This described technique holds promise for a more consistent and accurate method to evaluate the surgical trauma to the endothelial cell layer in laboratory models. This method of quantitative analysis can probably be generalized to any area of research that involves areas that are differentiated by color or contrast.