Author(s)
Melwan Izem, BS
Lumei Liu, PhD
Sarah Nyirjesy, MD
Ada C. Sher, BS
Zheng Hong Tan, PhD
Sayali Dharmadhikari, MS
Tendy Chiang, MD
Affiliation(s)
Nationwide Children's Hospital Abigail Wexner Research Institute;
Abstract:
Educational Objective: At the conclusion of this presentation, the participants should be able to analyze vascularization qualitatively and quantitatively on histological images.
Objectives: In surgical repair of tracheal defects, rapid neovascularization has been identified as the key source of successful surgical intervention. Allograft transplantations are known to cause microvasculature loss as cytotoxic T lymphocytes actively target endothelial cells, yielding vasculopathy and fibrosis. In this study, we aim to analyze vascularization of trachea isografts and allografts histologically at different timepoints, representing different degrees and stages of immunogenicity in tracheal graft healing.
Study Design: Tracheal replacement, vascularization, isografts, allografts, animal model.
Methods: Isografts from C57BL/6J and allografts from BALB/c mice were transplanted in C57BL/6J recipients. At day 10 (isografts N=3, allografts N=3), 1 month (isografts N=3, allografts N=8), and 3 months (isografts N=7, allografts N=7), grafts were harvested, sectioned, and stained with hematoxylin and eosin (H&E). Vessels were identified as tubular structures in the submucosa that contained red blood cells (RBCs) in H&E slides with adjacent slides showing CD31+ endothelial cells. Microvessel density (MVD, N/mm2), vascularity percentage, and average vessel size (AVS) were analyzed using ImageJ.
Results: Morphologically, allografts at day 10 showed excessive RBCs infiltration in submucosa without tubular vessels, indicating submucosal hemorrhage and acute rejection. No statistical difference was identified in % vascularity and AVS. Allografts had lower MVD at all timepoints when compared to native, (native: 4.304 +/- 2.023; allografts: 10d 0.9140 +/- 0.2960, p=0.0025; 1mon 0.9506 +/- 0.5768, p=0.0001; 3mon 1.212 +/- 0.3078, p=0.005). Isografts demonstrated no difference compared to allografts and native.
Conclusions: Immunogenicity appears to compromise allografts by inducing transient submucosal hemorrhage coupled with sustained microvasculature loss, hallmarks of acute rejection. Future study is to identify functional vessels and downstream effects of insufficient vascularization.