Demitria Tonelli
Research Mentor: Danny Nguyen
Mentor Department: Orthopedic Surgery, Medicine
Author(s): Danny Nguyen
Session: Session 6 (3:00 PM – 3:50 PM)
Presentation Type: Poster 74
Abstract
Post-traumatic osteoarthritis (PTOA) is a degenerative joint disease that can develop after injuries such as anterior cruciate ligament (ACL) rupture. Intra-articular adipose tissue may play an important role in disease progression, but it is difficult to quantify using standard imaging techniques. The objective of this study was to develop and optimize a reliable protocol for visualizing and quantifying joint fat using osmium tetroxide (OsTet) staining with contrast-enhanced micro-computed tomography (µCT). Hindlimbs from naïve mice were used to test different staining times, OsTet concentrations, and imaging parameters in order to identify conditions that produced consistent adipose tissue contrast while minimizing imaging artifacts. Histological analysis was performed to confirm staining specificity. After optimization, PTOA was induced in wild-type mice by anterior cruciate ligament rupture (ACLR) using a tibial compression overload model. Intra-articular adipose tissue volume and adipocyte density were then compared between injured knees and contralateral controls. The optimized protocol showed that 48 hours of incubation in 20 mL of 1% OsTet produced the most complete and consistent staining of intra-articular fat. Analysis of mice 28 days after ACLR revealed regional differences in fat loss within the joint, including an approximately 40% reduction in total fat fraction and a 20% decrease in adipocyte density in injured knees compared to controls. Importantly, this approach advances the current study of adipocyte remodeling by enabling three-dimensional reconstruction and joint-wide quantification of intra-articular adipose tissue, in contrast to the traditional two-dimensional histological analyses that have historically served as the gold standard. Overall, this work establishes OsTet-enhanced µCT as a reliable method for whole-joint visualization and quantification of adipose tissue, providing a valuable framework for future studies investigating the spatial and mechanistic aspects of PTOA pathogenesis.
