Leather and Shoe Research Association of New Zealand, Palmerston North, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand.
Leather and Shoe Research Association of New Zealand, Palmerston North, New Zealand.
Acta Biomater. 2022 Oct 15;152:113-123. doi: 10.1016/j.actbio.2022.08.057. Epub 2022 Aug 30.
Chemically crosslinked acellular bovine pericardium (ABP) has been widely used in clinical practice as bioprostheses. To ensure its consistency and durability, crosslinkers are used in excess, with stability guided by indicators including the hydrothermal denaturation temperature, the enzymatic resistance and the degree of crosslinking. Yet, understanding of the intermolecular structure in collagen fibrils which imparts the intrinsic stability of the ABPs is lacking, and the discrepancies in the stability criteria in varied conditions are poorly explained. In this study, synchrotron small-angle X-ray scattering (SAXS) in combination with thermal and colorimetric methods are employed to investigate the changes in the structure and the stability of ABPs during crosslinking using glutaraldehyde (GA) or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) at different concentrations. Based on the findings, a mechanism is proposed to explicate the crosslinking effects on collagen structure and the relationship between the structure and each stability indicator. At low crosslinker concentrations, the telopeptidyl-helical linkages are preferred, which cause rearrangements in the intermolecular structure of collagen, and efficiently contribute to its stabilities. Excess crosslinking is revealed by a revert trend in structural changes and the plateauing of the stabilities, assigning to the helical-helical linkages and monovalent bindings. The former would improve thermal stability but not collagenase resistance, whereas the latter have negligible effects. Overall, this study provides a mechanistic understanding of the chemical crosslinking of ABPs, which will contribute to the future development of more efficient and economically viable strategies to produce bioprostheses. STATEMENT OF SIGNIFICANCE: Chemical crosslinking imparts suitable properties to acellular bovine pericardium (ABP) for clinical applications, yet the understanding is lacking on the structure-stability relationship especially under different crosslinking conditions. Structural evidence in this study differentiates the binding sites during crosslinking in collagen fibrils at different crosslinker concentrations, highlighting the excess usage in the conventional crosslinking treatments. The mechanism based on the structure of collagen also successfully explains the dissimilarity in hydrothermal and enzymatic stabilities with varied crosslinking conditions. Future researches focusing on developing biomaterials via chemical crosslinking of ABPs would benefit from this study, for its contribution to the better understanding of the relationship of collagen structure and functions.
化学交联的去细胞牛心包 (ABP) 已广泛应用于临床作为生物假体。为了确保其一致性和耐久性，交联剂被过量使用，稳定性由包括水热处理变性温度、酶抗性和交联度在内的指标指导。然而，对于赋予 ABP 内在稳定性的胶原原纤维中分子间结构的理解还很缺乏，并且在不同条件下稳定性标准的差异也解释得很差。在这项研究中，使用同步加速器小角 X 射线散射 (SAXS) 结合热和比色法，研究了戊二醛 (GA) 或 1-乙基-3-(3-二甲基氨基丙基)碳二亚胺 (EDC) 在不同浓度下交联过程中 ABP 结构和稳定性的变化。基于这些发现，提出了一种机制来解释交联对胶原结构的影响以及结构与每种稳定性指标之间的关系。在低交联剂浓度下，优先形成末端肽-螺旋连接，导致胶原分子间结构的重排，并有效地提高其稳定性。通过结构变化的逆转趋势和稳定性的平台化，可以发现过量交联，这归因于螺旋-螺旋连接和单价结合。前者会提高热稳定性但不会提高胶原酶抗性，而后者则几乎没有影响。总的来说，这项研究提供了对 ABP 化学交联的机制理解，这将有助于未来开发更有效和经济可行的策略来生产生物假体。
化学交联赋予去细胞牛心包 (ABP) 适合临床应用的特性，但对结构-稳定性关系的理解，特别是在不同交联条件下的理解还很缺乏。本研究中的结构证据区分了不同交联剂浓度下胶原原纤维中交联过程中的结合位点，突出了传统交联处理中交联剂的过量使用。基于胶原结构的机制还成功地解释了不同交联条件下水热和酶稳定性的差异。未来专注于通过 ABP 的化学交联来开发生物材料的研究将受益于这项研究，因为它有助于更好地理解胶原结构和功能之间的关系。
