Critchley Susan, Sheehy Eamon J, Cunniffe Gráinne, Diaz-Payno Pedro, Carroll Simon F, Jeon Oju, Alsberg Eben, Brama Pieter A J, Kelly Daniel J
Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland.
Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Advanced Materials and Bioengineering Research Centre, Trinity College Dublin and Royal College of Surgeons in Ireland, Dublin, Ireland; Tissue Engineering Research Group, Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland.
Acta Biomater. 2020 Sep 1;113:130-143. doi: 10.1016/j.actbio.2020.05.040. Epub 2020 Jun 4.
Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage that is resistant to vascularization and endochondral ossification. During skeletal development articular cartilage also functions as a surface growth plate, which postnatally is replaced by a more spatially complex bone-cartilage interface. Motivated by this developmental process, the hypothesis of this study is that bi-phasic, fibre-reinforced cartilaginous templates can regenerate both the articular cartilage and subchondral bone within osteochondral defects created in caprine joints. To engineer mechanically competent implants, we first compared a range of 3D printed fibre networks (PCL, PLA and PLGA) for their capacity to mechanically reinforce alginate hydrogels whilst simultaneously supporting mesenchymal stem cell (MSC) chondrogenesis in vitro. These mechanically reinforced, MSC-laden alginate hydrogels were then used to engineer the endochondral bone forming phase of bi-phasic osteochondral constructs, with the overlying chondral phase consisting of cartilage tissue engineered using a co-culture of infrapatellar fat pad derived stem/stromal cells (FPSCs) and chondrocytes. Following chondrogenic priming and subcutaneous implantation in nude mice, these bi-phasic cartilaginous constructs were found to support the development of vascularised endochondral bone overlaid by phenotypically stable cartilage. These fibre-reinforced, bi-phasic cartilaginous templates were then evaluated in clinically relevant, large animal (caprine) model of osteochondral defect repair. Although the quality of repair was variable from animal-to-animal, in general more hyaline-like cartilage repair was observed after 6 months in animals treated with bi-phasic constructs compared to animals treated with commercial control scaffolds. This variability in the quality of repair points to the need for further improvements in the design of 3D bioprinted implants for joint regeneration. STATEMENT OF SIGNIFICANCE: Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage. In this study, we hypothesised that bi-phasic, fibre-reinforced cartilaginous templates could be leveraged to regenerate both the articular cartilage and subchondral bone within osteochondral defects. To this end we used 3D printed fibre networks to mechanically reinforce engineered transient cartilage, which also contained an overlying layer of phenotypically stable cartilage engineered using a co-culture of chondrocytes and stem cells. When chondrogenically primed and implanted into caprine osteochondral defects, these fibre-reinforced bi-phasic cartilaginous grafts were shown to spatially direct tissue development during joint repair. Such developmentally inspired tissue engineering strategies, enabled by advances in biofabrication and 3D printing, could form the basis of new classes of regenerative implants in orthopaedic medicine.
成功的骨软骨缺损修复需要再生软骨下骨，同时促进上层关节软骨的发育，使其具有抗血管化和软骨内成骨的能力。在骨骼发育过程中，关节软骨还起着表面生长板的作用，出生后被空间结构更复杂的骨 - 软骨界面所取代。受这一发育过程的启发，本研究的假设是，双相纤维增强软骨模板可以在山羊关节中创建的骨软骨缺损内再生关节软骨和软骨下骨。为了制造具有机械性能的植入物，我们首先比较了一系列3D打印纤维网络（PCL、PLA和PLGA）在机械增强藻酸盐水凝胶的同时，在体外支持间充质干细胞（MSC）软骨生成的能力。然后，这些机械增强的、负载MSC的藻酸盐水凝胶被用于构建双相骨软骨构建体的软骨内骨形成阶段，其上覆软骨阶段由使用髌下脂肪垫来源的干/基质细胞（FPSC）和软骨细胞共培养工程化的软骨组织组成。在进行软骨形成预处理并皮下植入裸鼠后，发现这些双相软骨构建体能够支持血管化软骨内骨的发育，其上方覆盖着表型稳定的软骨。然后，在临床相关的大型动物（山羊）骨软骨缺损修复模型中评估这些纤维增强的双相软骨模板。尽管不同动物之间的修复质量存在差异，但总体而言，与使用商业对照支架治疗的动物相比，接受双相构建体治疗的动物在6个月后观察到更多类似透明软骨的修复。修复质量的这种差异表明，用于关节再生的3D生物打印植入物的设计需要进一步改进。重要性声明：成功的骨软骨缺损修复需要再生软骨下骨，同时促进上层关节软骨的发育。在本研究中，我们假设可以利用双相纤维增强软骨模板在骨软骨缺损内再生关节软骨和软骨下骨。为此，我们使用3D打印纤维网络机械增强工程化的临时软骨，该软骨还包含一层使用软骨细胞和干细胞共培养工程化的表型稳定的软骨。当进行软骨形成预处理并植入山羊骨软骨缺损时，这些纤维增强的双相软骨移植物显示出在关节修复过程中对组织发育进行空间引导。这种受发育启发的组织工程策略，借助生物制造和3D打印的进步得以实现，可为骨科医学中的新型再生植入物奠定基础。
