Abstract
Purpose :
Corneal Schwann cells (cSCs) are glial cells that ensheath axons and provide trophic support for axons. Surgical procedures that lesion stromal axons often result in aberrant axonal regeneration with impaired sensation. This study aims to illuminate temporal and regio-specific changes in myelinating (m) and non-myelinating (nm) cSCs during injury by exploiting the proteolipid protein 1-enhanced green fluorescent protein (Plp1-egfp) mouse.
Methods :
Anesthetized adult male and female Plp1-egfp mice were subjected to stromal micropocket injury. Corneas were harvested 7, 14, and 30 days post-injury and processed for whole mount immunohistochemistry using antibodies against L1CAM (nm-cSCs), beta III-Tubulin (bIIITub), and NF-200 (m-SCs). Samples were analyzed by epifluorescence microscopy. NeuronJ (FIJI software) was used to quantify axonal and cSC network from high-resolution tiled images. The limbus-to-limbus corneal diameter was set at 3.8 mm and an internal 1.6 mm diameter for the central cornea. Statistical analysis was performed using ANOVA with Tukey’s multiple comparison test and results were considered significant with P < 0.05.
Results :
Comparisons of the L1CAM, NF200, and eGFP staining in control corneas for both total and central networks revealed significantly higher density for L1CAM and eGFP over NF200 in the central cornea. Upon injury, all markers were reduced significantly at 7 d, but returned at 14 d post-injury and exceeded controls levels. The network of eGFP cells in the central cornea at 14 d exceeded that of NF200. At 30 d post-injury, the total network of eGFP cells remained the highest. In the central cornea, the eGFP network was equivalent to L1CAM but significantly greater than NF200 cells. At 30 d the eGFP network was greater than that of NF200 and bIIITub at the peripheral cornea, identifying regional differences in the regeneration of SCs and axons.
Conclusions :
Our data suggest that differential expression of L1CAM and NF200 during SC restoration could contribute to aberrant axonal regeneration in the repairing central cornea. Regenerating cSCs apparently also initiate a pro-myelination repair program. This immunolocalization study examining the temporal and regio-specific changes in different cSC biomarkers could help advance our understanding of how these critical glial cells influence axonal growth and restore sensory function in injury and disease paradigms.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.