Discipline: Biological Sciences
Kenneth Terry, II - University of New Orleans
Co-Author(s): Scott Sullivan, LSUHSC, New Orleans, LA
Objective: While a variety of mouse strains are utilized in studies of corneal wound healing and nerve regeneration, it has been recently suggested that certain strains undergo different rates of epithelial regrowth after corneal injury. Furthermore, studies on diabetic corneas have shown different degrees of nerve loss between the sexes. As there is currently no standardization of mouse strain for experiments involving corneal nerve regeneration, we sought to compare 3 commonly used mouse strains to study the rate of wound healing, neurotrophin secretion, corneal sensitivity, and total nerve density following corneal injury. We also investigated whether the sex of the animal had any effect on the above measurements. Methods: Equal numbers of both males and females of the BALB/c, C57BL/6, and CFW mouse strains were obtained and evenly split into wound healing (n=18) and nerve regeneration (n=36) groups. In the wound healing experiment, corneal debridement with Algerbrush to ⅓ of the stromal depth confined to a 2mm diameter trephine was performed to the right eye of each mouse. Mice were then euthanized at 24-hours post-injury and the corneas stained with methylene blue for measurement of the wound area. Mice in the nerve regeneration group were subjected to sensitivity testing and tear film collection before injury and then regularly after injury on 3 day intervals for both injured and uninjured eyes. Pooled tear samples were analyzed via western blot for relative production of BDNF (Brain Derived Neurotrophic Factor) and NGF (Nerve Growth Factor). Half of the animals were euthanized at either day 7 or day 14 after injury for corneal extraction. Corneas were double stained with antibodies for PGP (Protein Gene Product) to determine total corneal sub-basal nerve density. Results: Wound healing rates in BALB/c and C57 mice were higher compared to the CFW strain at 24 hours after injury, while sex was also shown to significantly impact healing rates in each strain. BALB/c and C57 strains were also shown to have faster recovery of corneal sensitivity than CFW mice, though a significant difference between sexes was only found in the C57 strain. Western blot analyses revealed significant differences in tear secretion of BDNF throughout the recovery time period amongst all three strains for both injured and uninjured eyes of both sexes. No differences were found for NGF secretion. BALB/c mice were shown to have higher corneal nerve densities at 14 days after injury compared to C57 mice, though this was not found for the CFW mouse stock compared to the other strains. Conclusion: Our study shows that both the sex and strain of laboratory mouse used may significantly impact different indicators of corneal regeneration. These factors should be carefully considered by researchers investigating the mouse cornea.
Funder Acknowledgement(s): NSF, REU
Faculty Advisor: Ashok Puri, firstname.lastname@example.org
Role: I participated in every aspect of the research project.