Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.
Tissue Engineering Research Group (TERG), Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland; Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre (AMBER), Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland.
J Mech Behav Biomed Mater. 2021 Jun;118:104445. doi: 10.1016/j.jmbbm.2021.104445. Epub 2021 Mar 12.
Extracellular matrix (ECM)-derived scaffolds have shown promise as tissue-engineered grafts for promoting cartilage repair. However, there has been a lack of focus on fine-tuning the frictional properties of scaffolds for cartilage tissue engineering as well as understanding their interactions with synovial fluid constituents. Proteoglycan-4 (PRG4) and hyaluronan (HA) are macromolecules within synovial fluid that play key roles as boundary mode lubricants during cartilage surface interactions. The overall objective of this study was to characterize the role PRG4 and HA play in the lubricating function of collagen-glycosaminoglycan (GAG) scaffolds for cartilage repair. As a first step towards this goal, we aimed to develop a suitable in vitro friction test to establish the boundary mode lubrication parameters for collagen-GAG scaffolds articulated against glass in a phosphate buffered saline (PBS) bath. Subsequently, we sought to leverage this system to determine the effect of physiological synovial fluid lubricants, PRG4 and HA, on the frictional properties of collagen-GAG scaffolds, with scaffolds hydrated in PBS and bovine synovial fluid (bSF) serving as negative and positive controls, respectively. At all compressive strains examined (ε = 0.1-0.5), fluid depressurization within hydrated collagen-GAG scaffolds was >99% complete at ½ minute. The coefficient of friction was stable at all compressive strains (ranging from a low 0.103 ± 0.010 at ε = 0.3 up to 0.121 ± 0.015 at ε = 0.4) and indicative of boundary-mode conditions. Immunohistochemistry demonstrated that PRG4 from recombinant human (rh) and bovine sources adsorbed to collagen-GAG scaffolds and the coefficient of friction for scaffolds immersed in rhPRG4 (0.067 ± 0.027) and normal bSF (0.056 ± 0.020) solution decreased compared to PBS (0.118 ± 0.21, both p < 0.05, at ε = 0.2). The ability of the adsorbed rhPRG4 to reduce friction on the scaffolds indicates that its incorporation within collagen-GAG biomaterials may enhance their lubricating ability as potential tissue-engineered cartilage replacements. To conclude, this study reports the development of an in vitro friction test capable of characterizing the coefficient of friction of ECM-derived scaffolds tested in a range of synovial fluid lubricants and demonstrates frictional properties as a potential design parameter for implants and materials for soft tissue replacement.
细胞外基质 (ECM)-衍生的支架已被证明是组织工程移植物，可促进软骨修复。然而，人们一直缺乏关注来微调支架的摩擦特性，以用于软骨组织工程，并理解它们与滑液成分的相互作用。蛋白聚糖 4 (PRG4) 和透明质酸 (HA) 是滑液中的大分子，在软骨表面相互作用过程中作为边界模式润滑剂发挥关键作用。本研究的总体目标是研究 PRG4 和 HA 在胶原糖胺聚糖 (GAG) 支架修复软骨的润滑功能中的作用。作为实现这一目标的第一步，我们旨在开发一种合适的体外摩擦试验，以确定在磷酸盐缓冲盐水 (PBS) 浴中与玻璃摩擦的胶原-GAG 支架的边界模式润滑参数。随后，我们试图利用该系统来确定生理滑液润滑剂 PRG4 和 HA 对胶原-GAG 支架摩擦特性的影响，以 PBS 和牛滑液 (bSF) 水合的支架分别作为阴性和阳性对照。在所有检查的压缩应变 (ε=0.1-0.5) 下，水合胶原-GAG 支架内的流体减压在 1/2 分钟内完成>99%。在所有压缩应变下，摩擦系数均保持稳定 (范围从低至 0.103±0.010 在 ε=0.3 到 0.121±0.015 在 ε=0.4)，表明处于边界模式条件。免疫组织化学显示，重组人 (rh) 和牛源 PRG4 吸附到胶原-GAG 支架上，并且在 rhPRG4(0.067±0.027)和正常 bSF(0.056±0.020)溶液中浸泡的支架的摩擦系数与 PBS(0.118±0.21，均 p<0.05，在 ε=0.2)相比降低。吸附的 rhPRG4 降低支架摩擦的能力表明，将其掺入胶原-GAG 生物材料中可能会增强其润滑能力，作为潜在的组织工程软骨替代物。总之，本研究报告了一种体外摩擦试验的开发，该试验能够在一系列滑液润滑剂中对 ECM 衍生支架的摩擦系数进行特征化，并证明了摩擦特性作为软组织替代物植入物和材料的潜在设计参数。
