Palladino Sara, Copes Francesco, Chevallier Pascale, Candiani Gabriele, Mantovani Diego
Laboratory for Biomaterials and Bioengineering, CRC-Tier I, Department of Mining, Metallurgy and Materials Engineering and Regenerative Medicine CHU de Québec, Laval University, Quebec City, QC, Canada.
GenT_LΛB, Department of Chemistry, Materials and Chemical Engineering 'G. Natta', Politecnico di Milano, Milan, Italy.
Front Bioeng Biotechnol. 2024 Sep 4;12:1434435. doi: 10.3389/fbioe.2024.1434435. eCollection 2024.
The fabrication of cell-laden biomimetic scaffolds represents a pillar of tissue engineering and regenerative medicine (TERM) strategies, and collagen is the gold standard matrix for cells to be. In the recent years, extrusion 3D bioprinting introduced new possibilities to increase collagen scaffold performances thanks to the precision, reproducibility, and spatial control. However, the design of pure collagen bioinks represents a challenge, due to the low storage modulus and the long gelation time, which strongly impede the extrusion of a collagen filament and the retention of the desired shape post-printing. In this study, the tannic acid-mediated crosslinking of the outer layer of collagen is proposed as strategy to enable collagen filament extrusion. For this purpose, a tannic acid solution has been used as supporting bath to act exclusively as external crosslinker during the printing process, while allowing the pH- and temperature-driven formation of collagen fibers within the core. Collagen hydrogels (concentration 2-6 mg/mL) were extruded in tannic acid solutions (concentration 5-20 mg/mL). Results proved that external interaction of collagen with tannic acid during 3D printing enables filament extrusion without affecting the bulk properties of the scaffold. The temporary collagen-tannic acid interaction resulted in the formation of a membrane-like external layer that protected the core, where collagen could freely arrange in fibers. The precision of the printed shapes was affected by both tannic acid concentration and needle diameter and can thus be tuned. Altogether, results shown in this study proved that tannic acid bath enables collagen bioprinting, preserves collagen morphology, and allows the manufacture of a cell-laden pure collagen scaffold.
负载细胞的仿生支架的制造是组织工程和再生医学（TERM）策略的一个支柱，而胶原蛋白是细胞附着的金标准基质。近年来，挤出式3D生物打印由于其精确性、可重复性和空间控制能力，为提高胶原蛋白支架的性能带来了新的可能性。然而，由于储存模量低和凝胶化时间长，纯胶原蛋白生物墨水的设计面临挑战，这严重阻碍了胶原蛋白细丝的挤出以及打印后所需形状的保持。在本研究中，提出了用单宁酸介导胶原蛋白外层交联的策略，以实现胶原蛋白细丝的挤出。为此，单宁酸溶液被用作支撑浴，在打印过程中仅作为外部交联剂，同时允许在核心部位通过pH值和温度驱动形成胶原蛋白纤维。将胶原蛋白水凝胶（浓度为2-6mg/mL）挤出到单宁酸溶液（浓度为5-20mg/mL）中。结果证明，在3D打印过程中胶原蛋白与单宁酸的外部相互作用能够实现细丝挤出，而不影响支架的整体性能。胶原蛋白与单宁酸的临时相互作用导致形成了一层膜状外层，保护了核心部位，在该部位胶原蛋白可以自由排列成纤维。打印形状的精度受单宁酸浓度和针头直径的影响，因此可以进行调整。总之，本研究结果证明，单宁酸浴能够实现胶原蛋白生物打印，保留胶原蛋白形态，并允许制造负载细胞的纯胶原蛋白支架。
