Effect of shaking of corneal endothelial preservation

Manufacturing of human corneal endothelial grafts

PURPOSE

Human corneal endothelial cells (HCECs) play a significant role in maintaining visual function. However, these cells are notorious for their limited proliferative capacity in vivo. Current treatment of corneal endothelial dysfunction resorts to corneal transplantation. Herein we describe an ex vivo engineering method to manufacture HCEC grafts suitable for transplantation through reprogramming into neural crest progenitors.

METHODS

HCECs were isolated by collagenase A from stripped Descemet membrane of cadaveric corneoscleral rims, and induced reprogramming via knockdown with p120 and Kaiso siRNAs on collagen IV-coated atelocollagen. Engineered HCEC grafts were released after assessing their identity, potency, viability, purity and sterility. Phase contrast was used for monitoring cell shape, graft size, and cell density. Immunostaining was used to determine the normal HCEC phenotype with expression of N-cadherin, ZO-1, ATPase, acetyl-α-tubulin, γ-tubulin, p75NTR, α-catenin, β-catenin, and F-actin. Stability of manufactured HCEC graft was evaluated after transit and storage for up to 3 weeks. The pump function of HCEC grafts was measured by lactate efflux.

RESULTS

One HCEC graft suitable for corneal transplantation was generated from 1/8th of the donor corneoscleral rim with normal hexagonal cell shape, density, and phenotype. The manufactured grafts were stable for up to 3 weeks at 37 °C or up to 1 week at 22 °C in MESCM medium and after transcontinental shipping at room temperature by retaining normal morphology (hexagonal, >2000 cells/mm2, >8 mm diameter), phenotype, and pump function.

CONCLUSIONS

This regenerative strategy through knockdown with p120 and Kaiso siRNAs can be used to manufacture HCEC grafts with normal phenotype, morphology and pump function following prolonged storage and shipping.

Evaluation of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy

PURPOSE

To evaluate the effects of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy (SEM).

METHODS

Twenty-eight female rabbits were randomly divided into four equal groups. Rabbits in groups 1 and 2 underwent intracameral injection of 1 mg/0.1 mL and 0.5 mg/0.05 mL ranibizumab, respectively; group 3 was injected with 1.25 mg/0.05 mL bevacizumab. All three groups were injected with a balanced salt solution (BSS) into the anterior chamber of the left (fellow) eye. None of the rabbits in group 4 underwent an injection. Corneal thickness and intraocular pressure were measured before the injections, on the first day, and in the first month after injection. The rabbits were sacrificed and corneal tissues were excised in the first month after injection. Specular microscopy was used for the corneal endothelial cell count. Endothelial cell density was assessed and comparisons drawn between the groups and the control. Micrographs were recorded for SEM examination. The structure of the corneal endothelial cells, the junctional area of the cell membrane, the distribution of microvillus, and the cell morphology of the eyes that underwent intracameral injection of vascular endothelial growth factor (VEGF), BSS, and the control group were compared.

RESULTS

Corneal thickness and intraocular pressure were not significantly different between the groups that underwent anti-VEGF or BSS injection and the control group on the first day and in the first month of injection. The corneal endothelial cell count was significantly diminished in all three groups; predominantly in group 1 and 2 (P<0.05). The SEM examination revealed normal corneal endothelial histology in group 3 and the control group. Eyes in group 1 exhibited indistinctness of corneal endothelial cell borders, microvillus loss in the luminal surface, excessive blebbing, and disintegration of intercellular junctions. In group 2, the cell structure of the corneal endothelium and intercellular junctions were normal. However, a relative reduction was observed in the microvillus density of endothelial cells. Although eyes in group 3 were morphologically similar to fellow eyes and the control group, disarrangement in endothelial cell borders was evident.

CONCLUSION

The SEM examination pointed out deterioration in endothelial cell morphology after intracameral injection of 1 and 0.5 mg ranizumab. However, the effects of intracameral bevacizumab injection on corneal endothelial cells were similar to those found in fellow eyes and the control group. Further large-scale studies that examine the cellular changes by transmission electron microscopy are required to support the results of the present study that evaluates the structural changes in endothelial cells by SEM.

Donor and surgical risk factors for primary graft failure following Descemet's stripping automated endothelial keratoplasty in Asian eyes

Background

Descemet’s stripping automated endothelial keratoplasty (DSAEK) has been shown to have superior refractive and visual results compared with penetrating keratoplasty, but higher rates of primary graft failure (PGF). This paper presents donor and surgical risk factors for PGF in DSAEK cases in Asian eyes.

Design

Retrospective case-control study.

Participants

All consecutive patients who underwent DSAEK at a tertiary referral teaching hospital from March 2006–December 2008.

Methods

Donor details analyzed were: age of donor, cause of donor death, death to harvesting time, donor storage time, distribution distance of tissue, preoperative endothelial cell count. Surgical factors analyzed were: donor diameter, donor thickness, and method of donor insertion. These risk factors in cases of PGF were compared with patients with successful DSAEK as the control group.

Main outcome measure

PGF.

Results

A total of 124 DSAEK procedures were performed. Six DSAEK procedures (five eyes of five patients; one eye with two failures) resulted in PGF (4.8%). Significant risk factors were found for PGF to include graft insertion using a folding technique (odds ratio [OR], 34.03; 95% confidence interval [CI], 3.75–314.32; P = 0.0017) and a small donor diameter (OR, 39.94; 95% CI, 2.18–732.17; P = 0.013).

Conclusion

The results of this study suggest that in Asian eyes with shallow anterior chambers, surgical trauma relating to the technique of donor insertion, and the use of a small donor are major risk factors for PGF following DSAEK.

In situ versus whole-globe harvesting of corneal tissue from remote donor sites: effects on initial tissue quality

PURPOSE

There are 2 methods of corneal tissue procurement currently in widespread use: in situ extraction of the corneal button directly to preservation media and whole-globe enucleation of eyes with removal of the button to preservation media at a later time. This study evaluates the effects of these 2 procurement procedures on the initial quality of donor corneal tissue.

METHODS

Slit-lamp examination results and endothelial cell counts were compared for a total of 468 donor corneas harvested at 2 remote locations: one where in situ procurement was practiced and the other that used whole-globe enucleation procedures.

RESULTS

In both univariate and multivariate analysis, in situ corneas were found to have a lower incidence of moderate or severe haze and folds in Descemet membrane. No differences in mean endothelial cell counts were noted between the 2 populations of donated tissue.

CONCLUSIONS

In situ procurement of corneal tissue results in higher initial corneal tissue quality than whole-globe procedures.

Air Transportation of Corneal Tissue

PURPOSE

To compare the outcome of corneas obtained at the same hospital in which they were transplanted (group 1) to that of corneas obtained in the United States and grafted in Israel (group 2).

METHODS

One hundred twenty-six patients undergoing corneal grafting in Israel during the years 1995 to 1998 were included in a retrospective, nonrandomized clinical trial. Group 1 included 31 procedures, and group 2 included 95. Data regarding preoperative condition, tissue characteristics, and postoperative outcome were collected from hospital charts. Statistically significant difference between groups was considered as P < 0.05.

RESULTS

Follow-up time was 796 +/- 523 days for group 1 (mean +/- SD) and 815 +/- 510 days for group 2. Donor age and gender, recipient age and gender, graft size, and length of follow-up were similar. Time from preservation to transplantation was longer for group 2 (8.8 +/- 2.29 days) compared with in group 1 (3.13 +/- 2.38 days). Graft clarity was similar between groups 1 and 2 at 1 year (79% versus 71%) and at last follow-up visit (57% versus 62%). Visual acuity, intraocular pressure, and incidence of complications such as rejection (32% versus 38%), failure (35% versus 28%), secondary glaucoma (35% versus 43%), corneal ulcer (13% versus 6%), and regrafts (13% versus 7%) showed no difference between the groups.

CONCLUSIONS

Air transport of corneal tissue, including loss of time due to travel and handling, did not compromise corneal transplantation success rate.

[The influence of transport on organ cultured corneas. An experimental study of porcine corneal endothelium]

BACKGROUND

To investigate the influence of transport on the quality of corneas in organ culture, based on the vitality of the corneal endothelium.

METHODS

Transport was simulated for 222 porcine corneal disks. These were placed in standard transportation containers filled with organ culture medium II, kept in an incubator and then shaken on a laboratory shaker.

RESULTS

Agitated corneas at all acceleration rates always showed less endothelial cell damage than corneas kept motionless. The best condition was found after maximum accelerations of 0.10 g and 0.72 g. Damage consisted predominantly of disseminated cell loss and circular cell damage. A storage temperature of 37 degrees C caused most harm to the endothelium.

CONCLUSION

The reduction in endothelial damage found in corneas after agitation can be attributed to a better distribution of nutrients in the transportation container. Assuming transferability, a better quality of human grafts can be achieved by inducing slight motions of corneas in organ culture.

Effect of intracameral injection of lidocaine and carbachol on the rabbit corneal endothelium

PURPOSE

To determine the effect of intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% on corneal endothelial cells of rabbits.

SETTING

Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.

METHODS

Forty eyes of 20 New Zealand White rabbits were divided into 2 equal groups. In the first group, 1 eye was injected with 0.02 mL of preservative-free lidocaine 1% and the fellow eye was injected with 0.02 mL of normal saline as a control. In the second group, 1 eye was injected with 0.02 mL of carbachol 0.01% and the fellow eye was injected with 0.02 mL of normal saline. Specular microscopy was used to evaluate corneal endothelial cell loss and corneal thickness 1 week and 1 month postinjection. For morphologic studies, corneal buttons were excised and stained with alizarin red with trypan blue. Scanning electron microscopy (SEM) examination was performed.

RESULTS

Specular microscopy revealed no significant endothelial cell loss and normal endothelial thickness with the intracameral injection of preservative-free lidocaine 1% and carbachol 0.01% compared with the control eye. Alizarin red with trypan blue stain and SEM examinations revealed smooth, distinct, and intact intercellular borders and normal viability of corneal endothelial cells in both groups.

CONCLUSIONS

Intracameral injections of preservative-free lidocaine 1% and carbachol 0.01% do not produce morphologic and functional changes in the corneal endothelial cells of rabbits.

Effects of intraocular epinephrine on the corneal endothelium of rabbits

Epinephrine is frequently used in the phacoemulsification to dilate pupils. To determine the effects of different concentration of epinephrine on the corneal endothelial cells, twenty-eight rabbit eyes were equally divided into four groups. Solutions, which contained normal saline, 1:1000 epinephrine, 1:5000 epinephrine and 1:10000 epinephrine respectively, were injected into the anterior chambers of the eyes of four groups of rabbits. In vivo morphological changes of corneal endothelium and changes of thickness were checked with specular microscopy. In vitro morphological evaluation of corneal endothelium was observed in excised corneal buttons stained with alizarin red with trypan blue, and with scanning electron microscopy. Our results showed that there was no significant difference in cell density and corneal thickness among the four groups. Alizarin red with trypan blue stain and SEM exam revealed smooth and distinct cell borders of endothelial cells in each group. Intracameral injection of epinephrine does not produce toxic effect on corneal endothelial cells in rabbits.