Allogeneic simple limbal epithelial transplantation for bilateral limbal stem cell deficiency in chronic vernal keratoconjunctivitis: A case report

The application of a 4D-printed chitosan-based stem cell carrier for the repair of corneal alkali burns

BACKGROUND

Corneal alkali burns can lead to ulceration, perforation, and even corneal blindness due to epithelial defects and extensive cell necrosis, resulting in poor healing outcomes. Previous studies have found that chitosan-based in situ hydrogel loaded with limbal epithelium stem cells (LESCs) has a certain reparative effect on corneal alkali burns. However, the inconsistent pore sizes of the carriers and low cell loading rates have resulted in suboptimal repair outcomes. In this study, 4D bioprinting technology was used to prepare a chitosan-based thermosensitive gel carrier (4D-CTH) with uniform pore size and adjustable shape to improve the transfer capacity of LESCs.

METHODS

Prepare solutions of chitosan acetate, carboxymethyl chitosan, and β-glycerophosphate sodium at specific concentrations, and mix them in certain proportions to create a pore-size uniform scaffold using 4D bioprinting technology. Extract and culture rat LESCs (rLESCs) in vitro, perform immunofluorescence experiments to observe the positivity rate of deltaNp63 cells for cell identification. Conduct a series of experiments to validate the cell compatibility of 4D-CTH, including CCK-8 assay to assess cell toxicity, scratch assay to evaluate the effect of 4D-CTH on rLESCs migration, and Calcein-AM/PI cell staining experiment to examine the impact of 4D-CTH on rLESCs proliferation and morphology. Establish a severe alkali burn model in rat corneas, transplant rLESCs onto the injured cornea using 4D-CTH, periodically observe corneal opacity and neovascularization using a slit lamp, and evaluate epithelial healing by fluorescein sodium staining. Assess the therapeutic effect 4D-CTH-loaded rLESCs on corneal alkali burn through histological evaluation of corneal tissue paraffin sections stained with hematoxylin and eosin, as well as immunofluorescence staining of frozen sections.

RESULTS

Using the 4D-CTH, rLESCs were transferred to the alkali burn wounds of rats. Compared with the traditional treatment group (chitosan in situ hydrogel encapsulating rLESCs), the 4D-CTH-rLESC group had significantly higher repair efficiency of corneal injury, such as lower corneal opacity score (1.2 ± 0.4472 vs 0.4 ± 0.5477, p < 0.05) and neovascularization score (5.5 ± 1.118 vs 2.6 ± 0.9618, p < 0.01), and significantly higher corneal epithelial wound healing rate (72.09 ± 3.568% vs 86.60 ± 5.004%, p < 0.01).

CONCLUSION

In summary, the corneas of the 4D-CTH-rLESC treatment group were similar to the normal corneas and had a complete corneal structure. These findings suggested that LESCs encapsulated by 4D-CTH significantly accelerated corneal wound healing after alkali burn and can be considered as a rapid and effective method for treating epithelial defects.

Safety and Efficacy of Contact Lenses in Eyes After Simple Limbal Epithelial Transplantation

PURPOSE

The aim of this study was to evaluate the safety and efficacy of contact lenses (CLs) in eyes after simple limbal epithelial transplantation (SLET) for limbal stem cell deficiency (LSCD).

METHODS

This retrospective study included 61 eyes with partial or total LSCD which underwent SLET and were fitted with corneal or scleral rigid gas-permeable CLs. The primary outcome measure was best-corrected visual acuity (BCVA) with CLs.

RESULTS

The median age at presentation was 22 years. The most common cause of LSCD was chemical injury [47/61 eyes (77%)]. Twenty-seven eyes (44%) were fitted with corneal rigid gas-permeable lenses, while 34 eyes (56%) were prescribed scleral lenses. The median duration of interval between SLET and CL trial was 10 months (interquartile range: 4-17). The median preoperative BCVA was logarithm of minimal angle of resolution (logMAR) 1.8. This improved to logMAR 1 ( P < 0.001) after SLET and to logMAR 0.6 ( P < 0.001) with CLs. Eyes with chemical injury (logMAR 1 vs. 0.6, P = 0.0001), grade 1 (logMAR 0.8 vs. 0.4, P < 0.0001), and grade 2 (logMAR 0.9 vs. 0.6, P = 0.004) corneal scarring had better improvement in BCVA with CLs. No complications were noted until the last follow-up visit.

CONCLUSIONS

CLs, both corneal and scleral lenses, provide significant visual improvement in eyes after SLET with residual corneal scarring. These can be safely prescribed in such eyes without any adverse effects. This option can be considered before offering keratoplasty in these eyes.

Vernal Keratoconjunctivitis: A Systematic Review

Vernal keratoconjunctivitis (VKC) is a chronic, bilateral corneal and conjunctival problem which typically presents in young individuals. VKC is characterized by itching, photophobia, white mucous discharge, lacrimation, foreign body sensation, and pain due to corneal involvement of shield ulcers. Vernal keratoconjunctivitis is categorized within ocular diseases. The diagnosis is clinical, as no sure biomarkers pathognomonic of the disease have yet been identified. The VKC therapy relies on different types of drugs, from antihistamines and topical steroids to cyclosporine or tacrolimus eye drops. In extremely rare cases, there is also the need for surgical treatment for the debridement of ulcers, as well as for advanced glaucoma and cataracts, caused by excessive prolonged use of steroid eye drops. We performed a systematic review of the literature, according to PRISMA guideline recommendations. We searched the PubMed database from January 2016 to June 2023. Search terms were Vernal, Vernal keratoconjunctivitis, and VKC. We initially identified 211 articles. After the screening process, 168 studies were eligible according to our criteria and were included in the review. In this study, we performed a systematic literature review to provide a comprehensive overview of currently available diagnostic methods, management of VKC, and its treatments.