Study on polymethylmethacrylate ring in protecting limbal stem cells during collagen cross-linking

Area of Science:

• Ophthalmology
• Corneal Surgery
• Stem Cell Biology

Background:

• Corneal collagen cross-linking (CXL) uses UV radiation, which may harm vital limbal stem cells.
• Protecting limbal stem cells is crucial for maintaining corneal health and regenerative capacity post-CXL.

Purpose of the Study:

• To assess the protective efficacy of a polymethylmethacrylate (PMMA) hemiannulus shield against UV-induced damage to limbal stem cells during CXL.
• To evaluate the impact of PMMA shielding on limbal stem cell viability and marker expression after CXL.

Main Methods:

• Human cadaveric eyeballs underwent corneal CXL, with one sector shielded by a PMMA annulus and the other left unprotected.
• Limbal biopsies were collected pre- and post-CXL from both sectors for analysis.
• Biopsies were cultured on human amniotic membrane (HAM) and analyzed for stem cell marker ABCG2 expression using RT-PCR.

Main Results:

• Post-CXL, unprotected limbal biopsies (Sector A) showed no growth on HAM, unlike pre-CXL samples.
• Biopsies from the PMMA-shielded sector (Sector B) demonstrated growth on HAM in 2 out of 10 samples post-CXL.
• The stem cell marker ABCG2 was negative in all unprotected samples post-CXL, but positive in 2 shielded samples.

Conclusions:

• A PMMA hemiannulus provides partial protection to the limbus from UV radiation during the CXL procedure.
• PMMA shielding may help preserve limbal stem cell function and viability following corneal CXL.