Key Laboratory of Functional Polymer Materials, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
Biomacromolecules. 2011 Mar 14;12(3):578-84. doi: 10.1021/bm101187b. Epub 2011 Jan 19.
Organ printing is an alternative to the classic scaffold-based tissue engineering approach in which functional living macrotissues and organ constructs are fabricated by assembly of the building blocks: microtissue spheroids. However, the method for scalable fabrication of cell spheroids does not exist yet. We propose here that it may be a suitable one to generate cell spheroids in thermoreversible hydrogel scaffold, followed by liquefying the scaffold and releasing the generated spheroids. We show that concentrated poly(N-isopropylacrylamide-co-acrylic acid) microgel dispersions solidify upon heating and liquefy upon cooling. A hysteresis in the cooling process was observed and explained by the slow kinetics of the dissolution of the aggregated polymer chains in the cooling process due to additional intra- and interchain interactions. Hep G2 cells are seeded by simple mixing the cells with the microgel dispersions at room temperature. Cell/scaffold constructs form in situ when heated to 37 °C. The cells proliferate and form multicellular spheroids. When brought back to room temperature, the hydrogel scaffolds liquefy, thus, releasing the generated cell spheroids. The released spheroids can attach on the cell culture plate, disassemble, and spread on the substrate, confirming the cell viability. The whole process is carried out under mild conditions and does not involve any toxic additives, which may introduce injury to the cells or DNA. It is scalable and may meet the need for large scale fabrication of cell spheroids for organ printing.
器官打印是经典支架组织工程方法的替代方法，在经典支架组织工程方法中，通过组装构建块：微组织球体，制造功能性的活体大组织和器官结构。然而，目前还没有可用于大规模制造细胞球体的方法。在这里，我们提出可以在热可逆水凝胶支架中生成细胞球体，然后使支架液化并释放生成的球体。我们表明，浓缩的聚（N-异丙基丙烯酰胺-co-丙烯酸）微凝胶分散体在加热时固化，在冷却时液化。在冷却过程中观察到滞后现象，并通过聚合链在冷却过程中由于额外的链内和链间相互作用而溶解的缓慢动力学来解释。将 Hep G2 细胞通过简单地在室温下与微凝胶分散体混合来接种。当加热至 37°C 时，细胞/支架结构原位形成。细胞增殖并形成多细胞球体。当回到室温时，水凝胶支架液化，从而释放生成的细胞球体。释放的球体可以附着在细胞培养板上，解体并在基质上扩散，证实了细胞的活力。整个过程在温和的条件下进行，不涉及任何有毒添加剂，这些添加剂可能会对细胞或 DNA 造成伤害。它是可扩展的，可能满足器官打印对大规模制造细胞球体的需求。
