Background
Human menisci are fibrocartilaginous tissues with limited self-healing capacity due to their complex structure and presence of a large avascular zone. Major functions include shock absorption, improving stability of the knee joint, and load transmission. Given these vital functions in the high load-bearing setting of the knee, meniscus tears are one of the most frequent reported injuries in orthopaedic literature. The current gold standard for the treatment of meniscus tears - partial meniscectomy - affects knee biomechanics, and often results in an early onset of knee osteoarthritis. Therefore, development of alternative repair methods for damaged meniscus tissue is required, and should focus on preservation and restoration of native meniscal structure and function.
Objective
The aim of this study is to prepare a decellularized and sterilized meniscus allograft while maintaining compositional, structural, and mechanical properties. In the future, decellularized and sterilized meniscus allografts are aimed to be used as an off-the-shelf product for meniscus reconstruction.
Methods
Decellularized human meniscus scaffolds are developed using a twelve day long decellularization protocol. Half of the decellularized samples are sterilized using supercritical carbon dioxide to remove all microorganisms. To investigate decellularization efficiency, cell removal will be examined using biochemical assays and histological stainings. Secondly, preservation of biochemical composition and structural properties of extracellular matrix components will be examined upon decellularization and sterilization. Finally, biomechanical properties of meniscus specimens will be investigated through ball indentation tests.
Results
It was shown that the decellularization protocol reduced the total DNA content of human meniscus samples with 91%, to a value of 17,7 ± 3,7 ng DNA per mg tissue dry weight (p < 0.0003). This value is below the threshold of 50 ng DNA per mg tissue dry weight, set by decellularization criteria. Histological images confirm almost complete cell removal. Biochemical composition and structural properties of the extracellular matrix, in terms of collagen and glycosaminoglycans, were retained upon decellularization and sterilization (p > 0.05). Most importantly, biomechanical properties, in terms of stiffness, residual force, and compression, did not show any significant changes (p > 0.05) after decellularization and sterilization.
Conclusion
In conclusion, this study reports that the proposed decellularization protocol, in combination with sterilization, has high potential to prepare ideal allografts for meniscus replacement, with excellent removal of cellular components, and retained biochemical composition, and structural and biomechanical properties.