Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region of China, People's Republic of China.
School of Mechanical Engineering, Dongguan University of Technology, Dongguan, Guangdong, People's Republic of China.
Biofabrication. 2022 Aug 11;14(4). doi: 10.1088/1758-5090/ac84b0.
Compared to other conventional scaffold fabrication techniques, three-dimensional (3D) printing is advantageous in producing bone tissue engineering scaffolds with customized shape, tailored pore size/porosity, required mechanical properties and even desirable biomolecule delivery capability. However, for scaffolds with a large volume, it is highly difficult to get seeded cells to migrate to the central region of the scaffolds, resulting in an inhomogeneous cell distribution and therefore lowering the bone forming ability. To overcome this major obstacle, in this study, cell-laden bone tissue engineering scaffolds consisting of osteogenic peptide (OP) loaded-tricalcium phosphate (TCP)/poly(lactic--glycolic acid) (PLGA) (OP/TCP/PLGA, designated as OTP) nanocomposite struts and rat bone marrow derived mesenchymal stem cell (rBMSC)-laden gelatin/GelMA hydrogel rods were produced through 'dual-nozzle' low temperature hybrid 3D printing. The cell-laden scaffolds exhibited a bi-phasic structure and had a mechanical modulus of about 19.6 MPa, which was similar to that of human cancellous bone. OP can be released from the hybrid scaffolds in a sustained manner and achieved a cumulative release level of about 78% after 24 d. rBMSCs encapsulated in the hydrogel rods exhibited a cell viability of about 87.4% right after low temperature hybrid 3D printing and could be released from the hydrogel rods to achieve cell anchorage on the surface of adjacent OTP struts. The OP released from OTP struts enhanced rBMSCs proliferation. Compared to rBMSC-laden hybrid scaffolds without OP incorporation, the rBMSC-laden hybrid scaffolds incorporated with OP significantly up-regulated osteogenic differentiation of rBMSCs by showing a higher level of alkaline phosphatase expression and calcium deposition. This 'proof-of-concept' study has provided a facile method to form cell-laden bone tissue engineering scaffolds with not only required mechanical strength, biomimetic structure and sustained biomolecule release profile but also excellent cell delivery capability with uniform cell distribution, which can improve the bone forming ability in the body.
与其他传统支架制造技术相比，三维（3D）打印在制造具有定制形状、特定孔径/孔隙率、所需机械性能甚至理想生物分子输送能力的骨组织工程支架方面具有优势。然而，对于体积较大的支架，很难使接种细胞迁移到支架的中心区域，导致细胞分布不均匀，从而降低成骨能力。为了克服这一主要障碍，在本研究中，通过“双喷嘴”低温混合 3D 打印技术制备了负载成骨肽（OP）的磷酸三钙（TCP）/聚（乳酸-乙醇酸）（PLGA）（OP/TCP/PLGA，命名为 OTP）纳米复合支架和负载大鼠骨髓间充质干细胞（rBMSC）的明胶/甲基丙烯酰化明胶（GelMA）水凝胶棒的细胞负载骨组织工程支架。细胞负载支架呈现双相结构，机械模量约为 19.6 MPa，与人松质骨相似。OP 可以从混合支架中以持续的方式释放，并在 24 d 后达到约 78%的累积释放水平。低温混合 3D 打印后，水凝胶棒中包封的 rBMSCs 的细胞活力约为 87.4%，并可以从水凝胶棒中释放出来，实现在相邻 OTP 支架表面的细胞锚定。从 OTP 支架中释放的 OP 增强了 rBMSCs 的增殖。与未掺入 OP 的负载 rBMSC 的混合支架相比，掺入 OP 的负载 rBMSC 的混合支架显著上调了 rBMSCs 的成骨分化，表现出更高水平的碱性磷酸酶表达和钙沉积。这项“概念验证”研究提供了一种简便的方法，可形成具有所需机械强度、仿生结构和持续生物分子释放特征的细胞负载骨组织工程支架，同时具有优异的细胞输送能力，具有均匀的细胞分布，可提高体内成骨能力。
