Institute of Medical and Biological Engineering, School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom; Institute of Medical and Biological Engineering, School of Mechanical Engineering, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.
Institute of Medical and Biological Engineering, School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
J Mech Behav Biomed Mater. 2023 Mar;139:105671. doi: 10.1016/j.jmbbm.2023.105671. Epub 2023 Jan 11.
Decellularised porcine superflexor tendon (pSFT) has been characterised as a suitable scaffold for anterior cruciate ligament replacement, with dimensions similar to hamstring tendon autograft. However, decellularisation of tissues may reduce or damage extracellular matrix components, leading to undesirable biomechanical changes at a whole tissue scale. Although the role of collagen in tendons is well established, the mechanical contribution of glycosaminoglycans (GAGs) is less evident and could be altered by the decellularisation process. In this study, the contribution of GAGs to the tensile and compressive mechanical properties of pSFT was determined and whether decellularisation affected these properties by reducing GAG content or functionality. PSFTs were either enzymatically treated using chondroitinase ABC to remove GAGs or decellularised using previously established methods. Native, GAG-depleted and decellularised pSFT groups were then subjected to quantitative assays and biomechanical characterisation. In tension, specimens underwent stress relaxation and strength testing. In compression, specimens underwent confined compression testing. The GAG-depleted group was found to have circa 86% reduction of GAG content compared to native and decellularised groups. There was no significant difference in GAG content between native (3.75 ± 0.58 μg/mg) and decellularised (3.40 ± 0.37 μg/mg) groups. Stress relaxation testing discovered the time-independent and time-dependent relaxation moduli of the decellularised group were reduced ≥50% compared to native and GAG-depleted groups. However, viscoelastic behaviour of native and GAG-depleted groups resulted similar. Strength testing discovered no differences between native and GAG-depleted group's properties, albeit a reduction ∼20% for decellularised specimens' linear modulus and tensile strength compared to native tissue. In compression testing, the aggregate modulus was found to be circa 74% lower in the GAG-depleted group than the native and decellularised groups, while the zero-strain permeability was significantly higher in the GAG-depleted group (0.86 ± 0.65 mm/N) than the decellularised group (0.03 ± 0.04 mm/N). The results indicate that GAGs may significantly contribute to the mechanical properties of pSFT in compression, but not in tension. Furthermore, the content and function of GAGs in pSFTs are unaffected by decellularisation and the mechanical properties of the tissue remain comparable to native tissue.
去细胞化猪超弹性肌腱（pSFT）已被确定为前交叉韧带替代的合适支架，其尺寸与腘绳肌腱自体移植物相似。然而，组织的去细胞化可能会减少或破坏细胞外基质成分，导致整个组织尺度上不可取的生物力学变化。尽管胶原在肌腱中的作用已得到很好的证实，但糖胺聚糖（GAGs）的机械贡献不太明显，并且可能会因去细胞化过程而改变。在这项研究中，确定了 GAGs 对 pSFT 拉伸和压缩力学性能的贡献，以及去细胞化是否通过降低 GAG 含量或功能来影响这些性能。pSFT 要么用软骨素酶 ABC 进行酶处理以去除 GAGs，要么用先前建立的方法进行去细胞化。然后对天然、GAG 耗竭和去细胞化的 pSFT 组进行定量分析和生物力学表征。在张力下，标本进行了应力松弛和强度测试。在压缩下，标本进行了受限压缩测试。与天然和去细胞化组相比，GAG 耗竭组的 GAG 含量减少了约 86%。天然组（3.75±0.58μg/mg）和去细胞化组（3.40±0.37μg/mg）之间的 GAG 含量无显著差异。应力松弛测试发现，与天然和 GAG 耗竭组相比，去细胞化组的无时间依赖性和时间依赖性松弛模量降低了≥50%。然而，天然和 GAG 耗竭组的粘弹性行为结果相似。强度测试发现天然组和 GAG 耗竭组的性质没有差异，尽管与天然组织相比，去细胞化标本的线性模量和拉伸强度降低了约 20%。在压缩测试中，与天然和去细胞化组相比，GAG 耗竭组的聚集模量低约 74%，而 GAG 耗竭组的零应变渗透率（0.86±0.65mm/N）明显高于去细胞化组（0.03±0.04mm/N）。结果表明，GAGs 可能在压缩下显著影响 pSFT 的力学性能，但在拉伸下则不然。此外，pSFT 中的 GAG 含量和功能不受去细胞化的影响，并且组织的力学性能与天然组织相当。
