Current Status of Genetically Engineered Pig to Monkey Kidney Xenotransplantation in Korea.

BACKGROUND: In South Korea, pig-to-nonhuman primate trials of solid organs have only been performed recently, and the results are not sufficiently satisfactory to initiate clinical trials. Since November 2011, we have performed 30 kidney pig-to-nonhuman primate xenotransplantations at Konkuk University Hospital. METHODS: Donor αGal-knockout-based transgenic pigs were obtained from 3 institutes. The knock-in genes were CD39, CD46, CD55, CD73, and thrombomodulin, and 2-4 transgenic modifications with GTKO were done. The recipient animal was the cynomolgus monkey. We used the immunosuppressants anti-CD154, rituximab, anti-thymocyte globulin, tacrolimus, mycophenolate mofetil, and steroids. RESULTS: The mean survival duration of the recipients was 39 days. Except for a few cases for which survival durations were <2 days because of technical failure, 24 grafts survived for >7 days, with an average survival duration of 50 days. Long-term survival was observed 115 days after the removal of the contralateral kidney, which is currently the longest-recorded graft survival in Korea. We confirmed functioning grafts for the surviving transplanted kidneys after the second-look operation, and no signs of hyperacute rejection were observed. CONCLUSIONS: Although our survival results are relatively poor, they are the best-recorded results in South Korea, and the ongoing results are improving. With the support of government funds and the volunteering activities of clinical experts, we aim to further improve our experiments and contribute to the commencement of clinical trials of kidney xenotransplantation in Korea.

Comparison of Graft Survival Between Full-Thickness and Lamellar Pig-to-Monkey Corneal Xenotransplantation from the Same Genetically Engineered Pig Model with Minimal Immunosuppression.

BACKGROUND: The graft survival rate of full-thickness corneal xenotransplantation (XTP) with minimal immunosuppression in genetically engineered pigs is unknown, whereas lamellar corneal XTP shows satisfactory results. We compared graft survival between full-thickness and lamellar transplantations in the same genetically engineered pig. METHODS: Six pig-to-monkey corneal transplantations were performed on 3 transgenic pigs. Two corneas harvested from 1 pig were transplanted into 2 monkeys using full-thickness and lamellar corneal xenotransplantation. The transgenic donor pigs used were α1,3-galactosyltransferase gene-knockout + membrane cofactor protein (GTKO+CD46) in one recipient and GTKO+CD46+ thrombomodulin (TBM) in the other. RESULTS: The graft survival time for GTKO+CD46 XTP was 28 days. With the addition of TBM, the survival differences between lamellar and full-thickness XTP were 98 days versus 14 days and >463 days (ongoing) versus 21 days, respectively. An excessive number of inflammatory cells was observed in failed grafts, but none were in the recipient's stromal bed. CONCLUSIONS: Unlike full-thickness corneal XTP, lamellar xenocorneal transplantation does not exhibit surgical complications, such as retrocorneal membrane or anterior synechia. The graft survival of lamellar XTP in this study was not as good as in our previous experiments, although the survival period was superior to that of full-thickness XTP. The difference in graft survival based on transgenic type is not definitive. Further studies using transgenic pigs and minimal immunosuppression need to focus on improving graft survival of lamellar XTP and using a larger sample size to determine the potential of full-thickness corneal XTP.

Identification of the trochlea with reference to the lacrimal caruncle, and its significance as a landmark in orbitofacial surgery.

PURPOSE: The purpose of this study was to identify the location of the trochlea in order to prevent injury during orbitofacial surgery and to determine the reliability of the lacrimal caruncle as a visible external landmark for the trochlea at the superomedial orbital rim. METHODS: Fifty-one orbits from 27 embalmed cadavers were dissected. The lacrimal caruncle and supraorbital notch/foramen were used as external and bony landmarks, respectively. The location of the trochlea was determined with respect to these structures, and the size of trochlea was measured. RESULTS: The trochlea was 3.6 mm wide and 5.6 mm long, with a flange breadth of 5.4 mm. The vertical distance from the apex of the lacrimal caruncle to the superolateral tip of the trochlea was 15.8 mm, and that from the top of the supraorbital notch/foramen to the bottom of the trochlea was 11.4 mm. As the coefficient of variation and standard deviation were smaller for DCT (11.5 and 1.8, respectively) than for DST (17.0 and 1.9, respectively), it appears that the lacrimal caruncle is a reliable landmark. CONCLUSIONS: In contrast to the supraorbital notch, the lacrimal caruncle allows easy identification and serves as a reliable and visible external landmark for the prediction of the location of trochlea. The trochlea was located directly at 15.8 mm (i.e., approximately 1.5 cm) superior to the lacrimal caruncle. This anatomical study has yielded accurate measurements of the location of the trochlea, which may facilitate a safer orbitofacial surgery by preventing morbidity associated with trochlea injury.

Comparison of conventional versus crossed monovision in pseudophakia.

AIMS: To compare the visual performances and patient satisfactions of conventional monovision, which corrects the dominant eye for distance vision, and crossed monovision, which corrects the non-dominant eye for distance vision in patients with pseudophakia. METHODS: This prospective randomised study was conducted in 59 patients who underwent implantation of different targets of monofocal intraocular lens for each eye at Konkuk University Medical Center between November 2009 and August 2012. The following were examined before bilateral cataract surgery and 2 months after the surgery: refractive error, binocular uncorrected distance visual acuity (UCDVA), uncorrected near visual acuity (UCNVA), best corrected visual acuity (BCVA) and stereopsis. Questionnaires to evaluate postoperative spectacle dependence and patient satisfaction were completed by all patients. RESULTS: The conventional monovision group and the crossed monovision group were composed of 28 and 31 patients, respectively. There were no significant differences in postoperative UCDVA, UCNVA, BCVA and stereopsis between the two groups. In addition, patient satisfaction with near and distant vision and spectacle dependence were not significantly different in the two groups. CONCLUSIONS: The clinical results of the crossed monovision were not significantly different from the results of conventional monovision. Therefore, crossed monovision can also be a valuable option for correcting postoperative presbyopia in patients considering bilateral cataract surgery. TRIAL REGISTRATION NUMBER: KCT0001065.

Change of retinal nerve fiber layer thickness in various retinal diseases treated with multiple intravitreal antivascular endothelial growth factor.

PURPOSE: To investigate the effect of multiple intravitreal injection of anti-VEGF on the retinal nerve fiber layer (RNFL) in AMD, diabetes mellitus retinopathy (DMR), and retinal vein occlusion (RVO). METHODS: In this retrospective controlled case series, we reviewed the AMD, DMR, and RVO patients who received more than three anti-VEGF injections (injection group: 148 eyes). Patients without treatment were included as a control group (noninjection group: 183 eyes). RNFL thickness was measured by SD-OCT. Also, correlation between RNFL change and associated factors, including intraocular pressure (IOP), injection times, and severity of retinal ischemia, were analyzed using multivariate logistic regression. RESULTS: RNFL thickness (µm) had not changed in AMD, but it decreased from 100.0 to 97.1, and from 101.1 to 98.0 in injection groups of DMR and RVO, respectively, as well as the noninjection group. However, decreased RNFL thickness of the injection groups was not significantly different from those of the noninjection groups. Severity of retinal ischemia was associated with decreased RNFL thickness (odds ratio: 4.667). However, number of injections and IOP-related variables had no association with RNFL change. CONCLUSIONS: Multiple intravitreal injections of anti-VEGF did not lead to significant change in RNFL thickness in wet AMD, DMR, and RVO patients. Furthermore, IOP fluctuations and number of injections did not appear to adversely affect RNFL thickness. Decreased RNFL thickness associated with severity of retinal ischemia in the DMR and RVO patients suggests that inner retinal ischemia itself could be a cause of RNFL loss rather than anti-VEGF effect.

Central corneal thickness and corneal endothelial cell changes caused by contact lens use in diabetic patients.

PURPOSE: To analyze the effects of soft contact lenses on central corneal thickness and morphologic characteristics of the corneal endothelium in diabetic patients. MATERIALS AND METHODS: Ultrasound pachymetry and noncontact specular microscopy were performed on 26 diabetic patients who regularly use soft contact lenses (group 1), 27 diabetic patients who do not use soft contact lenses (group 2) and 30 normal subjects (group 3). We compared the values in each group using the Mann-Whitney test. RESULTS: The central cornea was found to be thicker in diabetic patients, both those who use and do not use contact lenses, than in the normal control group. The central corneal thickness was significantly higher in group 1 (564.73 ± 35.41 µm) and group 2 (555.76 ± 45.96 µm) than in the control group (534.05 ± 27.02 µm), but there was no statistically significant difference between groups 1 and 2. Endothelial cell density was significantly different between the groups, and was smallest in the group of diabetic patients using contact lenses. The coefficient of variation of cell size was significantly higher and the percentage of hexagonal cells was significantly lower in contact lens using diabetic patients than in non-contact lens using diabetic patients and in the control group. CONCLUSION: Central corneal thickness and endothelial cell density is more affected by diabetes mellitus, and corneal endothelial cell morphology is more affected by contact lens use, when compared with normal subjects.

Preliminary effects of oral uridine on the ocular surface in dry eye patients.

We designed a randomized, double blinded, 3-months controlled prospective clinical study to investigate effects of oral uridine on the ocular surface in dry eye patients. Twenty-seven patients who diagnosed as dry eye with lower than 5 mm of wetting in the Schirmer strip, with corneal epithelial erosion and who completely followed-up till 3 months were enrolled. Corneal-conjunctival fluorescein staining, non-anesthetic Schirmer test, impression cytology, and Ocular Surface Disease Index (OSDI) were evaluated in the experimental and placebo groups at the baseline, 1 and 3 months after start of medication in a double blinded manner. Fluorescein stain score of the cornea was markedly decreased in oral uridine group compared to the placebo group at 3 months after medication (P=0.032, Mann-Whitney U test). The Schirmer wetting score for the oral uridine group was significantly increased (P=0.001, Wilcoxon signed rank test) at 3 months and its difference between two groups was statistically significant (P=0.030, Mann-Whitney U test). OSDI scores were significantly decreased at 1 and 3 months in treatment group. Oral uridine is effective in treatment of dry eyes.

Protective effect of uridine on cornea in a rabbit dry eye model.

PURPOSE: To investigate the effect of uridine on cultured human corneal epithelial cells and keratocytes in vitro and to evaluate whether the application of uridine-containing eye drops could improve ocular surface health in an in vivo dry eye model. METHODS: Uridine was added to cultured epithelial cells (3 x 10(4) cells/well) and keratocytes (1 x 10(4) cells/well) at various concentrations (0.5-50 microM). Cytotoxicity was tested with the use of MTT assay, and the cells were assessed for apoptosis with the use of flow cytometry. Expressions of hyaluronic acid (HA), glycosaminoglycan (GAG), nitric oxide (NO), and matrix metalloproteinase (MMP)-9 were measured. In vivo, the degree of reepithelialization was assessed after topical application of uridine (100 microM) in a rabbit corneal wound model. Changes in tear production and conjunctival goblet cell counts were investigated after instillation of various concentrations of uridine-containing eye drops in a rabbit dry eye model. RESULTS: In vitro, uridine showed no cellular toxicity. It increased the biosynthesis of HA and GAG and reduced MMP-9 levels in cultured corneal epithelial cells and keratocytes. In vivo, uridine enhanced corneal wound healing and significantly increased the number of conjunctival goblet cells in rabbits. CONCLUSIONS: Uridine can restore the health of the ocular surface in a rabbit corneal wound and dry eye model.

The effect of contact lens wear on the ocular surface changes in keratoconus.

PURPOSE: To investigate the effects of contact lens wear or the keratoconic shape itself on the changes in the ocular surface in keratoconus. METHODS: Forty-two patients (84 eyes) were enrolled in this study and divided into four groups. Group 1 comprised 22 eyes with keratoconus that had been wearing rigid gas-permeable (RGP) contact lenses for an average of 5.54 +/- 2.11 years. Group 2 comprised 24 myopic eyes that had been wearing RGP contact lenses for 6.42 +/- 1.79 years. Group 3 comprised 20 eyes with keratoconus without any contact lens wear. Group 4 comprised 18 healthy eyes that were used as controls. The ocular surface changes were evaluated by determining the tear film breakup time and performing conjunctival impression cytology. The goblet cell densities, nucleus-to-cytoplasm ratio, and epithelial cell morphology in the four groups were compared with optical microscopy in the high-power field. RESULTS: The tear film breakup times in groups 1 and 2 were significantly lower than those in groups 3 and 4. The goblet cell densities were 5.49 +/- 1.75 and 5.82 +/- 1.63 in groups 1 and 2, respectively, which were significantly lower (P < 0.05) than the 8.79 +/- 1.42 and 10.24 +/- 2.10 in groups 3 and 4, respectively. There were no statistically significant differences in the goblet cell densities, nucleus-to-cytoplasm ratios, and epithelial cell morphologies between groups 1 and 2 and groups 3 and 4. CONCLUSIONS: The ocular surface changes in keratoconus may be directly related to contact lens wear and not to the keratoconic shape itself.