Abstracts Health Sciences

An Examination of the LG/J Murine Strain as a Model ofTendon Regeneration

by Jessica R Arble

Musculoskeletal injuries are common in the United States, with injuries to tendons accounting for 30% of reported injuries2. Injuries to tendons are difficult to repair and usually do not heal to normal properties, resulting in a high risk of rerupture and often a need for further medical intervention. Understanding how tendons heal after injury is a vital part of creating successful strategies to improve healing outcomes. We have previously evaluated the tendon healing of the MRL/MpJ murine strain, which is known for regenerative healing. In this study, we evaluate the healing of the LG/J murine strain, which comprises 75% of the MRL/MpJ strain, to determine if the LG/J strain exhibits improved healing. A full-length central patellar tendon defect was introduced at 16 weeks of age. Mechanical properties and histology were assessed at 2, 5, and 8 weeks post surgery. Tissue stain markers were placed on the tendon and photographed throughout the tensile test to allow for calculations of regional strain. Tendons were loaded into grips and preloaded to a value of 0.02 N, at which point the tendons were photographed for cross-sectional area optical measurements. Tendons were tested in 37°C PBS, preconditioned from 0 to 1% strain for 25 cycles, and then ramped to failure at 0.1% of length/second.Average LG/J structural properties improved to near-native values at 8 weeks, with normal tendons displayed an average ultimate load of 4.29 ± 1.5 N and stiffness of 10.88 ± 2.34 N/mm. Tendons after healing displayed an ultimate load of 4.17 ± 1.2 N and stiffness of 10.52 ± 3.40 N/mm. At 8 weeks, stiffness was at 96.7% of normal and ultimate load was at 97.2% of normal. Elastic modulus reached 92% of normal and maximum stress reached 86% of normal by 8 weeks.The LG/J strain returns to normal mechanical properties by 8 weeks, with a steady increase in properties at each time point, in contrast to the MRL/MpJ strain which does not return to normal properties by 8 weeks and exhibits a drop in properties from 2 to 5 weeks post surgery. Future studies will focus on analyzing the transcriptome and the proteome to understand the healing process employed by the LG/J strain, with a long term goal of utilizing the genes and pathways responsible for increased LG/J healing in regenerative medicine and tissue engineering applications. Advisors/Committee Members: Shearn, Jason (Committee Chair).