Evaluating Long-Term Retention of Fresh-Frozen Costal Cartilage Allograft in An Animal Model

Data is limited regarding the in-vivo behavior of fresh-frozen costal cartilage allografts (CCA). This study aims to evaluate retention and biological behavior of CCA in an immunocompetent mouse model.

Clinical-grade fresh-frozen CCA (MTF Profile ®) from 4 donors, subcutaneously implanted into 9 SKH-1 mice. Cartilage size and volume were evaluated at 2 and 6 weeks, and 3, 6, and 9 months, using clinical assessment, digital-caliper measures, and micro-CT scan volumetric analysis. Linear measurements, total volume, and volume of calcification were compared across time-points. After sacrifice, H&E staining was performed for comparison at 3, 6, and 9 months.

There were no significant changes in cartilage implant length (p = 0.16), width (p = 0.21), or total volume (p = 0.9) across timepoints. Average volume of calcified cartilage increased from 1.1% to 10% of total volume (p<.001). Clinical assessment did not show evident change. Clinical assessment did not show overt changes in implant appearance. Histology demonstrated capsule formation without evidence of undue inflammatory response or resorption.

This study evaluated the in-vivo behavior of new forms of CCA currently used in practice, with implications for clinical use in facial reconstruction. We found no significant resorption or morphologic changes in fresh-frozen CCA when implanted in an immunocompetent murine model at 9 months. Although reassuring for continued use and stability long-term, further work is needed to understand the impact of cartilage calcification.Clinical Relevance: Fresh-frozen CCA demonstrated structural stability and detail preservation with minimal to no resorption, when implanted in our immunocompetent mouse model over our 9-month study period. However, progressive calcification of the graft was also observed, which may impact superficial applications.