Etanercept Enhances Preservation of Osteochondral Allograft Viability

Abstract

Background: Osteochondral allografts are an increasingly popular treatment for the repair of articular cartilage lesions. Current tissue bank protocols require bacteriological testing that takes from 21 to 28 days to process. During this time, tumor necrosis factor–alpha (TNF-α, a proapoptotic cytokine) is upregulated, resulting in loss of chondrocyte viability. To date, etanercept (a cytokine inhibitor) has not been studied in the current storage paradigm with the intention of preserving cell viability.

Purpose: This study was undertaken to assess whether the addition of etanercept can improve the chondrocyte viability ofosteochondral allograft during storage.

Study Design: Controlled laboratory study.

Methods: Osteochondral allografts were harvested from 8 Boer goat femurs and placed into storage media and stored at 4°C for 28 days. The experimental group was supplemented with 10 µg/mL of etanercept. After storage, cell viability was assessed by live/dead staining and confocal microscopy. Specimens were also analyzed histologically and underwent histomorphologic analysis. TNF-α expression was measured with semiquantitative polymerase chain reaction.

Results: At 28 days, the percentage viability of the superficial zone in etanercept-treated allografts was maintained at significantly higher levels than those measured in the untreated group (69.3 ± 9.4 compared with 47.8 ± 19.1, P = .01). No difference was found histologically between the etanercept and the untreated group (ie, safranin O staining for glycosaminoglycan expression). Histomorphologic assessment showed no difference in indentation stiffness or roughness between groups. TNF-α expression was significantly decreased in the etanercept group compared to the untreated group.

Conclusion: Etanercept was able to maintain cell viability of osteochondral allografts significantly better than the current storage paradigm after 28 days of storage.

Clinical Relevance: Maintaining the viability of the superficial zone will benefit outcomes by facilitating joint articulation via improved lubrication. Additionally, maintaining the cellular viability for increased periods of time may allow a greater window of time in which a suitable recipient may be found.