Quantification of Retained Donor Nuclei in ECM-Based Nerve Wraps: A Histological Assessment of Decellularization and Biocompatibility

Background: Peripheral nerve injuries present a significant clinical challenge, often resulting in chronic pain, sensory loss, and motor dysfunction. Biologically derived nerve wraps are frequently used in surgical nerve repair to reduce adhesion, promote regeneration, and minimize fibrosis. These extracellular matrix (ECM)-based biomaterials vary widely in composition and processing, including the extent of donor decellularization. Retained donor nuclei and cellular remnants have been implicated in triggering adverse immune responses, including chronic inflammation and fibrotic encapsulation. This study investigates the extent of retained nuclear material in commercially available nerve wraps to establish histological metrics for decellularization efficiency and potential biocompatibility. Methods: Samples of multiple commercially available nerve wraps were collected and prepared according to manufacturer specifications. Histological assessment was performed using hematoxylin and eosin (H&E) staining. Slides were analyzed at 20× magnification using a standardized fluorescence imaging system. Two primary endpoints were quantified: (1) the number of visible nuclei per three representative microscopic fields and (2) the percentage of cell-free fields per sample. Results: Substantial variability was observed among products. One reconstituted xenograft and a porcine placental product demonstrated complete decellularization with >90% cell free fields and <10 nuclei per field. In contrast, both a native porcine small intestinal submucosa and a human amnion/chorion membrane exhibited high nuclear retention with >50 nuclei per field and 0% cell free fields. These findings suggest inconsistent decellularization practices across manufacturers. Conclusion: This study identifies significant differences in residual donor nuclear content among commercially available ECM nerve wraps. Histological quantification using H&E staining may serve as a reproducible method for assessing decellularization quality. These metrics may help predict immunologic compatibility and guide future biomaterial selection in peripheral nerve repair.