Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street, NW, Washington, DC, 20052, USA.
Nanotechnology. 2016 Oct 14;27(41):414001. doi: 10.1088/0957-4484/27/41/414001. Epub 2016 Sep 8.
Osteochondral tissue has a complex graded structure where biological, physiological, and mechanical properties vary significantly over the full thickness spanning from the subchondral bone region beneath the joint surface to the hyaline cartilage region at the joint surface. This presents a significant challenge for tissue-engineered structures addressing osteochondral defects. Fused deposition modeling (FDM) 3D bioprinters present a unique solution to this problem. The objective of this study is to use FDM-based 3D bioprinting and nanocrystalline hydroxyapatite for improved bone marrow human mesenchymal stem cell (hMSC) adhesion, growth, and osteochondral differentiation. FDM printing parameters can be tuned through computer aided design and computer numerical control software to manipulate scaffold geometries in ways that are beneficial to mechanical performance without hindering cellular behavior. Additionally, the ability to fine-tune 3D printed scaffolds increases further through our investment casting procedure which facilitates the inclusion of nanoparticles with biochemical factors to further elicit desired hMSC differentiation. For this study, FDM was used to print investment-casting molds innovatively designed with varied pore distribution over the full thickness of the scaffold. The mechanical and biological impacts of the varied pore distributions were compared and evaluated to determine the benefits of this physical manipulation. The results indicate that both mechanical properties and cell performance improve in the graded pore structures when compared to homogeneously distributed porous and non-porous structures. Differentiation results indicated successful osteogenic and chondrogenic manipulation in engineered scaffolds.
软骨组织具有复杂的梯度结构，其生物学、生理学和机械性能在关节表面下的骨软骨区域到关节表面的透明软骨区域的整个厚度上都有显著变化。这对用于治疗骨软骨缺陷的组织工程结构提出了重大挑战。熔丝制造（Fused Deposition Modeling，FDM）3D 生物打印机为解决这个问题提供了独特的解决方案。本研究的目的是使用基于 FDM 的 3D 生物打印和纳米晶羟基磷灰石来提高骨髓间充质干细胞（human mesenchymal stem cell，hMSC）的黏附、生长和骨软骨分化。FDM 打印参数可以通过计算机辅助设计和计算机数控软件进行调整，以通过有利于机械性能的方式操纵支架的几何形状，而不会阻碍细胞行为。此外，通过我们的熔模铸造工艺，可以进一步微调 3D 打印支架，该工艺可以方便地将纳米颗粒与生化因素结合，以进一步引发所需的 hMSC 分化。在本研究中，创新性地使用 FDM 打印了具有全厚度变化的孔隙分布的熔模铸造模具。比较和评估了不同孔隙分布的机械和生物学影响，以确定这种物理处理的益处。结果表明，与均匀分布的多孔和无孔结构相比，分级孔隙结构可提高机械性能和细胞性能。分化结果表明，在工程支架中成功进行了成骨和成软骨的操作。
