Center of Sports Medicine of Orthopaedic Department, Southwest hospital, Third Military Medical University, Chongqing 400038, China.
Biomater Sci. 2020 Jul 7;8(13):3649-3663. doi: 10.1039/d0bm00229a. Epub 2020 May 27.
Treatment of tendon-to-bone interface injury has long been challenging in sports medicine. The major obstacle lies with the complicated three-layer structure of the tissue that consists of a bone region with osteocytes, a tendon region with tenocytes and a transitional region with chondrocytes. Conventional tissue engineering approaches using simply biomaterial scaffolds, stem cells and combinations of them had limited abilities to reconstruct the gradient structure with normal biomechanical properties. We herein aim to construct a three-layer structure with bone marrow-derived stem cells and tendon stem cells cultured in a decellularized tendon scaffold, through application of a gradient of biological cues in the longitudinal direction of the scaffold that guides the stem cells to differentiate and remodel the extracellular matrix in response to different medium concentrations in different regions. A microfluidic chip, on which a tree-like flow pattern was implemented, was adopted to create the concentration gradient in a dichotomous manner. We screened for an optimized seeding ratio between the two stem cell types before incubation of the scaffold in the medium concentration gradient and surgical implantation. Histology and immunohistochemistry assessments, both qualitatively and semi-quantitatively, showed that the microfluidic system provided desired guidance to the seeded stem cells that the healing at 8-week post-implantation presented a similar structure to that of a normal tendon-to-bone interface, which was outstanding compared to treatments without gradient guidance, stem cells or scaffolds where chaotic and fibrotic structures were obtained. This strategy offers a potentially translational tissue engineering approach for better outcomes in tendon-to-bone healing.
治疗肌腱-骨界面损伤一直是运动医学领域的一大挑战。主要的障碍在于组织的复杂三层结构，包括具有骨细胞的骨区、具有腱细胞的腱区和具有软骨细胞的过渡区。传统的组织工程方法，单纯使用生物材料支架、干细胞及其组合，重建具有正常生物力学特性的梯度结构的能力有限。在此，我们旨在通过在脱细胞肌腱支架中培养骨髓来源的干细胞和肌腱干细胞，构建具有三层结构的组织，在支架的纵向应用生物信号梯度，引导干细胞分化，并根据不同区域中不同介质浓度重塑细胞外基质。采用具有树状流型的微流控芯片以二叉方式创建浓度梯度。在将支架孵育在介质浓度梯度中和进行手术植入之前，我们筛选了两种干细胞类型之间的最佳接种比例。组织学和免疫组织化学评估，无论是定性还是半定量评估，都表明微流控系统为接种的干细胞提供了所需的指导，在植入后 8 周的愈合呈现出与正常肌腱-骨界面相似的结构，与没有梯度引导、干细胞或支架的治疗方法相比，这是一个显著的改善，因为后两者得到的是混乱和纤维性的结构。这种策略为肌腱-骨愈合提供了一种有潜力的转化组织工程方法，以获得更好的结果。
