*Purpose: Liver diseases are recognized as the second leading cause of mortality amongst all digestive diseases in the United States. Orthotopic liver transplantation leads to high survival rates, yet the number of donor livers fall short of the worldwide need. Importantly, thousands of livers are discarded due to conditions such as advanced age. To ameliorate this gap, we aim to repurpose the discarded human donor livers through whole liver decellularization and subsequent recellularization with patient-specific cells. The purpose of this study is to assess the effect of advanced donor age on liver extracellular matrix (ECM) composition and structural organization as it is crucial to consider the variation in quality and age of the discarded donor livers in translating this approach to clinical settings.

*Methods: We decellularized 4 young (17-48 years old) and 4 aged (48 years old and older) whole human livers through a 4 day-long protocol where the livers were perfused with deionized water (16h) followed by 24h perfusions of 0.1, 0.2, and 0.5% sodium dodecyl sulfate through portal vein and hepatic artery followed by washes with Triton X-100 (3h) and phosphate buffered saline (3h). Biopsy samples were collected from tip and center of right and left lobes, center of caudate and quadrate lobes, back and core of liver (behind caudate lobe). Total DNA, collagen, and glycosaminoglycan (GAG) contents were assessed using commercial assays and mass spectrometry and histology analysis was used to examine structural composition and organization.

*Results: We successfully removed more than 90% of DNA from all livers on average. The homogeneity of DNA removal, as indicated by the variation in DNA amount found in different sections of the liver showed that aged livers had a less homogenous decellularization. We determined that aged livers had higher collagen and GAG content compared to young livers and further differences were detected through mass spectrometry. Histology analysis showed that the structural integrity was preserved in livers regardless of age while aged livers had higher remaining fat content.

*Conclusions: Our results indicate that there are age-related alterations in liver ECM composition and structure which affect the decellularization outcomes. Through further characterization of livers from different aged donors, the widely varying discarded donor livers can be classified, thus be used effectively as decellularized scaffolds to develop human liver substitutes with high functionality and regenerative capacity.

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