Department of Sports Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, PR China.
Department of Orthopedics, The First Affiliated Hospital of Soochow University, Orthopedic Institute, Soochow University, 708 Renmin Road, Suzhou, Jiangsu 215006, PR China.
Acta Biomater. 2017 Oct 1;61:204-216. doi: 10.1016/j.actbio.2017.07.044. Epub 2017 Aug 1.
Enthesis is a specialized tissue interface between the tendon and bone. Enthesis structure is very complex because of gradient changes in its composition and structure. There is currently no strategy to create a suitable environment and to regenerate the gradual-changing enthesis because of the modular complexities between two tissue types. Herein, a dual-layer organic/inorganic flexible bipolar fibrous membrane (BFM) was successfully fabricated by electrospinning to generate biomimetic non-mineralized fibrocartilage and mineralized fibrocartilage in tendon-to-bone integration of enthesis. The growth of the in situ apatite nanoparticle layer was induced on the nano hydroxyapatite-poly-l-lactic acid (nHA-PLLA) fibrous layer in simulated body solution, and the poly-l-lactic acid (PLLA) fibrous layer retained its original properties to induce tendon regeneration. The in vivo results showed that BFM significantly increased the area of glycosaminoglycan staining at the tendon-bone interface and improved collagen organization when compared to the simplex fibrous membrane (SFM) of PLLA. Implanting the bipolar membrane also induced bone formation and fibrillogenesis as assessed by micro-CT and histological analysis. Biomechanical testing showed that the BFM group had a greater ultimate load-to-failure and stiffness than the SFM group at 12weeks after surgery. Therefore, this flexible bipolar nanofibrous membrane improves the healing and regeneration process of the enthesis in rotator cuff repair.
In this study, we generated a biomimetic dual-layer organic/inorganic flexible bipolar fibrous membrane by sequential electrospinning and in situ biomineralization, producing integrated bipolar fibrous membranes of PLLA fibrous membrane as the upper layer and nHA-PLLA fibrous membrane as the lower layer to mimic non-mineralized fibrocartilage and mineralized fibrocartilage in tendon-to-bone integration of enthesis. Flexible bipolar nanofibrous membranes could be easily fabricated with gradient microstructure for enthesis regeneration in rotator cuff tears.
附着点是肌腱和骨骼之间的一种特殊组织界面。由于其组成和结构的梯度变化，附着点结构非常复杂。由于两种组织类型之间的模块复杂性，目前还没有策略来创造一个合适的环境并再生逐渐变化的附着点。在此，通过静电纺丝成功制备了双层有机/无机柔性双极纤维膜（BFM），以在附着点的肌腱-骨整合中产生仿生非矿化纤维软骨和矿化纤维软骨。在模拟体液中，诱导原位磷灰石纳米颗粒层在纳米羟基磷灰石-聚 L-乳酸（nHA-PLLA）纤维层上生长，而聚 L-乳酸（PLLA）纤维层保留其原始特性以诱导肌腱再生。体内结果表明，与 PLLA 的单纤维膜（SFM）相比，BFM 显著增加了肌腱-骨界面处糖胺聚糖染色的面积，并改善了胶原组织。植入双极膜也通过微 CT 和组织学分析诱导了骨形成和原纤维形成。生物力学测试表明，在手术后 12 周，BFM 组的极限失效载荷和刚度均大于 SFM 组。因此，这种柔性双极纳米纤维膜改善了肩袖修复中附着点的愈合和再生过程。
在这项研究中，我们通过顺序静电纺丝和原位生物矿化生成了仿生双层有机/无机柔性双极纤维膜，在上层为 PLLA 纤维膜，下层为 nHA-PLLA 纤维膜，产生了类似于肌腱-骨整合中的非矿化纤维软骨和矿化纤维软骨的集成双极纤维膜。柔性双极纳米纤维膜可以很容易地用梯度微观结构制造，用于肩袖撕裂中的附着点再生。
