Dellaquila Alessandra, Campodoni Elisabetta, Tampieri Anna, Sandri Monica
Institute of Science and Technology for Ceramics, National Research Council of Italy (ISTEC-CNR), Faenza, Italy.
Front Bioeng Biotechnol. 2020 Jul 7;8:743. doi: 10.3389/fbioe.2020.00743. eCollection 2020.
Scaffolds for bone regeneration have been engineered by a plethora of manufacturing technologies and biomaterials. However, the performance of these systems is often limited by lack of robustness in the process design, that hampers their scalability to clinical application. In the present study, Design of Experiment (DoE) was used as statistical tool to design the biofabrication of hybrid hydroxyapatite (HA)/collagen scaffolds for bone regeneration and optimize their integration in a multilayer osteochondral device. The scaffolds were synthesized via a multi-step bioinspired process consisting in HA nano-crystals nucleation on the collagen self-assembling fibers and ribose glycation was used as collagen cross-linking method to modulate the mechanical and physical properties. The process design was performed by selecting hydrogel concentration, HA/collagen ratio and cross-linker content as key variables and the fabrication was carried out basing on a full factorial design. Scaffold performances were tested by evaluating porosity, swelling ratio, degradation rate and mechanical behavior as model output responses while physicochemical properties of the constructs were evaluated by TGA, ICP, FT-IR spectroscopy, and XRD analysis. Physicochemical characterizations confirmed the nucleation of a biomimetic inorganic phase and the interaction of the HA and collagenic components. The DoE model revealed a significant interaction between HA content and collagen cross-linking in determining porosity, swelling and mechanical properties of the scaffolds. The combined effect of hydrogel concentration and mineral phase played a key role on porosity and swelling while degradation resulted to be mainly affected by the HA loading and ribose content. The model was then used to determine the suitable input parameters for the synthesis of multi-layer scaffolds with graded mineralization rate, that can be used to mimic the whole cartilage-bone interface. This work proved that experimental design applied to complex biofabrication processes represents an effective and reliable way to design hybrid constructs with standardized and tunable properties for osteochondral tissue engineering.
用于骨再生的支架已通过大量制造技术和生物材料制造出来。然而，这些系统的性能常常受到工艺设计缺乏稳健性的限制，这阻碍了它们向临床应用的扩展。在本研究中，实验设计（DoE）被用作统计工具，以设计用于骨再生的混合羟基磷灰石（HA）/胶原蛋白支架的生物制造，并优化它们在多层骨软骨装置中的整合。支架通过多步仿生过程合成，该过程包括在胶原蛋白自组装纤维上进行HA纳米晶体成核，并使用核糖糖基化作为胶原蛋白交联方法来调节机械和物理性能。通过选择水凝胶浓度、HA/胶原蛋白比例和交联剂含量作为关键变量来进行工艺设计，并基于全因子设计进行制造。通过评估孔隙率、溶胀率、降解率和机械性能作为模型输出响应来测试支架性能，同时通过热重分析（TGA）、电感耦合等离子体质谱（ICP）、傅里叶变换红外光谱（FT-IR）和X射线衍射（XRD）分析来评估构建体的物理化学性质。物理化学表征证实了仿生无机相的成核以及HA和胶原成分之间的相互作用。DoE模型揭示了HA含量和胶原蛋白交联在决定支架的孔隙率、溶胀和机械性能方面存在显著相互作用。水凝胶浓度和矿相的综合作用对孔隙率和溶胀起关键作用，而降解主要受HA负载量和核糖含量的影响。然后使用该模型来确定合成具有分级矿化速率的多层支架的合适输入参数，该支架可用于模拟整个软骨-骨界面。这项工作证明，应用于复杂生物制造过程的实验设计是一种有效且可靠的方法，可用于设计具有标准化和可调性能的混合构建体，用于骨软骨组织工程。
