Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart, Nobelstraße 12, D-70569 Stuttgart, Germany.
Biofabrication. 2017 Nov 14;9(4):044103. doi: 10.1088/1758-5090/aa91ec.
Though bioprinting is a forward-looking approach in bone tissue engineering, the development of bioinks which are on the one hand processable with the chosen printing technique, and on the other hand possess the relevant mechanical as well as osteoconductive features remains a challenge. In the present study, polymer solutions based on methacrylated gelatin and methacrylated hyaluronic acid modified with hydroxyapatite (HAp) particles (5 wt%) were prepared. Encapsulation of primary human adipose-derived stem cells in the HAp-containing gels and culture for 28 d resulted in a storage moduli significantly increased to 126% ± 9.6% compared to the value on day 1 by the sole influence of the HAp. Additional use of osteogenic media components resulted in an increase of storage module up to 199% ± 27.8%. Similarly, the loss moduli was increased to 370% ± 122.1% under the influence of osteogenic media components and HAp. Those changes in rheological material characteristics indicate a distinct change in elastic and viscous hydrogel properties, and are attributed to extensive matrix production in the hydrogels by the encapsulated cells, what could also be proven by staining of bone matrix components like collagen I, fibronectin, alkaline phosphatase and osteopontin. When using the cell-laden polymer solutions as bioinks to build up relevant geometries, the ink showed excellent printability and the printed grid structure's integrity remained intact over a culture time of 28 d. Again, an intense matrix formation as well as upregulation of osteogenic markers by the encapsulated cells could be shown. In conclusion, we demonstrated that our HAp-containing bioinks and hydrogels on basis of methacrylated gelatin and hyaluronic acid are on the one hand highly suitable for the build-up of relevant three-dimensional geometries with microextrusion bioprinting, and on the other hand exhibit a significant positive effect on bone matrix development and remodeling in the hydrogels, as indicated by rheological measurements and staining of bone components. This makes the developed composite hydrogels an excellent material for bone bioprinting approaches.
虽然生物打印是骨组织工程的一种前瞻性方法，但开发生物墨水仍然是一个挑战，这些生物墨水一方面要能够用所选的打印技术进行处理，另一方面要具有相关的机械和骨诱导特性。在本研究中，制备了基于甲基丙烯酰化明胶和经羟基磷灰石（HAp）颗粒（5wt%）改性的甲基丙烯酰化透明质酸的聚合物溶液。将原代人脂肪来源干细胞包封在含 HAp 的凝胶中，并培养 28 天，结果表明，仅 HAp 的影响就使储存模量显著增加到 126%±9.6%，比第 1 天的数值增加了 126%±9.6%。另外，使用成骨培养基成分可将存储模块增加到 199%±27.8%。同样，在成骨培养基成分和 HAp 的影响下，损耗模量增加到 370%±122.1%。这些流变材料特性的变化表明，水凝胶的弹性和粘性特性发生了明显变化，这归因于包封细胞在水凝胶中大量产生基质，这也可以通过对骨基质成分如胶原 I、纤连蛋白、碱性磷酸酶和骨桥蛋白的染色来证明。当使用负载细胞的聚合物溶液作为生物墨水构建相关几何形状时，该墨水表现出优异的可打印性，并且打印的网格结构的完整性在 28 天的培养时间内保持完整。同样，可以证明包封细胞强烈的基质形成和上调成骨标志物。总之，我们证明了我们的基于甲基丙烯酰化明胶和透明质酸的含 HAp 生物墨水和水凝胶一方面非常适合用微挤出生物打印技术构建相关的三维几何形状，另一方面在水凝胶中的骨基质发展和重塑方面表现出显著的积极影响，这可以通过流变测量和骨成分的染色来证明。这使得开发的复合水凝胶成为骨生物打印方法的优秀材料。
