Development of a Scaffold with Optimal Structure and Application to a Hybrid Artificial Liver for Chronic Liver Failure Patients

1.椭圆形中空纤维作为类器官形成支架的研究利用肝细胞类器官，我们研制了一种具有组织样结构的混合型人工肝。类器官培养中的一个主要问题是类器官核心处的氧耗尽。这种类器官的存活厚度受到氧气供应的限制，因为氧气是通过从类器官表面扩散来运输的。类器官的最佳厚度范围约为100 - 150μm。因此，我们试图开发一种支架，以控制类器官的厚度在合适的值。我们用一种简单的退火方法设计了一个小直径小于150μm的椭圆形HF。所有肝细胞都被供应氧气，并在该中空纤维中形成没有死细胞层的类器官。在培养过程中，椭圆形中空纤维中的肝细胞类器官至少在一个月内保持两倍于原始中空纤维中的氨去除活性。椭圆形中空纤维中的类器官的白蛋白分泌活性也维持至少一个月，并且与活体中的肝脏的白蛋白分泌活性处于相同水平。这些结果表明，利用椭圆形中空纤维进行类器官培养是一种很有前途的技术，可以用于混合型人工肝的研制。2.椭圆形中空纤维混合型人工肝模块的研制设计了一种椭圆形中空纤维混合型人工肝模块。该组件的总体积为4.3 cm^3，固定在组件中的中空纤维的数量为336根。将肝细胞固定在中空纤维的内腔中。此后，在灌注培养中评价模块。这种新的模块在至少一个月的培养中保持高水平的肝脏特异性功能。总之，这些类器官的培养和模块使用椭圆形HF似乎是一个有前途的技术，以开发一个混合型人工肝。

1.Development of an elliptic hollow fiber as a novel scaffold for organoid formationWe have been developed a hybrid artificial liver by using a hepatocyte organoid, which has a tissue-like structure. One major problem in organoid culture is the depletion of oxygen at the core of an organoid. The survival thickness of such an organoid is limited by oxygen supply, because oxygen is transported by diffusion from the surface of an organoid. The optimum range of the thickness of an organoid is about 100 - 150μm. So we are trying to develop a scaffold to control the thickness of the organoid within suitable value. We designed an elliptic HF having less than 150μm minor diameter by using a simple annealing method. All hepatocytes were supplied with oxygen and formed an organoid without a dead cell layer in this hollow fiber. A hepatocyte organoid in an elliptic hollow fiber maintained ammonia removal activity twice as high as in the original hollow fiber for at least one month during culture. Albumin secretion activity of an organoid in an elliptic hollow fiber was also maintained for at least one month and was the same level as that of liver in a living body. These results indicate that an organoid culture by using an elliptic hollow fiber seems to be a promising technique to develop a hybrid artificial liver.2.Development of a hybrid artificial liver module with elliptic hollow fibersWe designed a hybrid artificial liver module with elliptic hollow fibers. Total volume of this module was 4.3 cm^3, and number of hollow fiber immobilized in the module was 336. Hepatocytes were immobilized in lumen of hollow fibers. Following this, the module was evaluated in perfusion culture. This novel module was maintained liver specific functions at high level for at least one month of culture. In conclusion, these organoid culture and module by using an elliptic HF seems to be a promising technique to develop a hybrid artificial liver.