Engineering Science and Mechanics Department, The Pennsylvania State University, State College, PA, United States of America. The Huck Institutes of the Life Sciences, The Pennsylvania State University, State College, PA, United States of America.
Biofabrication. 2018 Nov 23;11(1):015009. doi: 10.1088/1758-5090/aaec22.
The scalability of cell aggregates such as spheroids, strands, and rings has been restricted by diffusion of nutrient and oxygen into their core. In this study, we introduce a novel concept in generating tissue building blocks with micropores, which represents an alternative solution for vascularization. Sodium alginate porogens were mixed with human adipose-derived stem cells, and loaded into tubular alginate capsules, followed by de-crosslinking of the capsules. The resultant cellular structure exhibited a porous morphology and formed cell aggregates in the form of strands, called 'porous tissue strands (pTSs).' Three-dimensional reconstructions show that pTSs were able to maintain ∼25% porosity with a high pore interconnectivity (∼85%) for 3 weeks. Owing to the porous structure, pTSs showed up-regulated cell viability and proliferation rate as compared to solid counterparts throughout the culture period. pTSs also demonstrated self-assembly capability through tissue fusion yielding larger-scale patches. In this paper, chondrogenesis and osteogenesis of pTSs were also demonstrated, where the porous microstructure up-regulated both chondrogenic and osteogenic functionalities indicated by cartilage- and bone-specific immunostaining, quantitative biochemical assessment and gene expression. These findings indicated the functionality of pTSs, which possessed controllable porosity and self-assembly capability, and had great potential to be utilized as tissue building blocks in distinct applications such as cartilage and bone regeneration.
细胞聚集体（如球体、链状和环状结构）的可扩展性受到营养物质和氧气向其核心扩散的限制。在本研究中，我们提出了一种生成具有微孔的组织构建块的新概念，这为血管生成提供了一种替代解决方案。将海藻酸钠致孔剂与人脂肪来源干细胞混合，并装入管状海藻酸钠胶囊中，随后对胶囊进行去交联处理。所得细胞结构呈现多孔形态，并以称为“多孔组织链（pTS）”的形式形成链状细胞聚集体。三维重建表明，pTS 能够在 3 周内保持约 25%的孔隙率和 85%的高孔连通性。由于多孔结构，pTS 在整个培养期间的细胞活力和增殖率均高于固体对照物。pTS 还通过组织融合表现出自组装能力，从而形成更大规模的斑块。本文还证明了 pTS 的软骨生成和成骨分化能力，其中多孔微结构通过软骨和骨特异性免疫染色、定量生化评估和基因表达，上调了软骨和成骨功能。这些发现表明了 pTS 的功能，其具有可控的孔隙率和自组装能力，在软骨和骨再生等不同应用中具有很大的应用潜力。
