Kim Minwook, Farrell Megan J, Steinberg David R, Burdick Jason A, Mauck Robert L
McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center (TMRC), Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA 19104, USA.
McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center (TMRC), Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA 19104, USA.
Acta Biomater. 2017 Aug;58:1-11. doi: 10.1016/j.actbio.2017.06.025. Epub 2017 Jun 16.
Biomimetic design in cartilage tissue engineering is a challenge given the complexity of the native tissue. While numerous studies have generated constructs with near-native bulk properties, recapitulating the depth-dependent features of native tissue remains a challenge. Furthermore, limitations in nutrient transport and matrix accumulation in engineered constructs hinders maturation within the central core of large constructs. To overcome these limitations, we fabricated tri-layered constructs that recapitulate the depth-dependent cellular organization and functional properties of native tissue using zonally derived chondrocytes co-cultured with MSCs. We also introduced porous hollow fibers (HFs) and HFs/cotton threads to enhance nutrient transport. Our results showed that tri-layered constructs with depth-dependent organization and properties could be fabricated. The addition of HFs or HFs/threads improved matrix accumulation in the central core region. With HF/threads, the local modulus in the deep region of tri-layered constructs nearly matched that of native tissue, though the properties in the central regions remained lower. These constructs reproduced the zonal organization and depth-dependent properties of native tissue, and demonstrate that a layer-by-layer fabrication scheme holds promise for the biomimetic repair of focal cartilage defects.
Articular cartilage is a highly organized tissue driven by zonal heterogeneity of cells, extracellular matrix proteins and fibril orientations, resulting in depth-dependent mechanical properties. Therefore, the recapitulation of the functional properties of native cartilage in a tissue engineered construct requires such a biomimetic design of the morphological organization, and this has remained a challenge in cartilage tissue engineering. This study demonstrates that a layer-by-layer fabrication scheme, including co-cultures of zone-specific articular CHs and MSCs, can reproduce the depth-dependent characteristics and mechanical properties of native cartilage while minimizing the need for large numbers of chondrocytes. In addition, introduction of a porous hollow fiber (combined with a cotton thread) enhanced nutrient transport and depth-dependent properties of the tri-layered construct. Such a tri-layered construct may provide critical advantages for focal cartilage repair. These constructs hold promise for restoring native tissue structure and function, and may be beneficial in terms of zone-to-zone integration with adjacent host tissue and providing more appropriate strain transfer after implantation.
鉴于天然组织的复杂性，软骨组织工程中的仿生设计是一项挑战。虽然众多研究已生成具有接近天然整体特性的构建体，但重现天然组织深度依赖性特征仍是一项挑战。此外，工程构建体中营养物质运输和基质积累的限制阻碍了大型构建体中心核心区域的成熟。为克服这些限制，我们使用与间充质干细胞共培养的区域来源软骨细胞制造了三层构建体，该构建体重现了天然组织的深度依赖性细胞组织和功能特性。我们还引入了多孔中空纤维（HFs）和HFs/棉线以增强营养物质运输。我们的结果表明，可以制造出具有深度依赖性组织和特性的三层构建体。添加HFs或HFs/线改善了中心核心区域的基质积累。对于HF/线，三层构建体深部区域的局部模量几乎与天然组织的局部模量匹配，尽管中心区域的特性仍然较低。这些构建体重现了天然组织的区域组织和深度依赖性特性，并证明逐层制造方案有望用于局灶性软骨缺损的仿生修复。
关节软骨是一种高度有组织的组织，由细胞、细胞外基质蛋白和纤维取向的区域异质性驱动，导致具有深度依赖性的力学特性。因此，在组织工程构建体中重现天然软骨的功能特性需要对形态组织进行这种仿生设计，而这在软骨组织工程中仍然是一项挑战。本研究表明，包括特定区域关节软骨细胞和间充质干细胞共培养的逐层制造方案可以重现天然软骨的深度依赖性特征和力学特性，同时将对大量软骨细胞的需求降至最低。此外，引入多孔中空纤维（与棉线结合）增强了三层构建体的营养物质运输和深度依赖性特性。这种三层构建体可能为局灶性软骨修复提供关键优势。这些构建体有望恢复天然组织结构和功能，并且在与相邻宿主组织的区域间整合以及植入后提供更合适的应变传递方面可能是有益的。
