Bioartificial devices for treatment of neurologic diseases

有报道称多巴胺释放细胞移植可治疗帕金森病，吗啡释放细胞移植可减轻终末期癌症患者的严重疼痛。同种异体和异种细胞移植失败的主要原因是免疫反应。为了克服这一问题，将细胞包裹在半透性聚合物膜中进行移植，这种膜必须能渗透氧气、营养物质和生物活性物质等小分子，但不能渗透淋巴细胞、免疫球蛋白和补体蛋白。此外，中枢神经系统很难找到大量移植的空间。因此，研究了细胞聚集体的离心微胶囊化来解决这些问题。球形细胞聚集体悬浮在海藻酸盐溶液中。在内径为14mm的12ml玻璃试管中，将0.4 ml悬浮液覆盖在三层的顶部，这三层由2.5 ml的7wt %葡聚糖层、0.5 ml的BaCl2溶液层和0.5 ml的13wt %葡聚糖层组成。在170 x g下离心试管10分钟，使聚集体旋转到试管底部。这种方法可以有效地将细胞聚集体包裹在微胶囊中，微胶囊的壁很薄，而不会污染空微胶囊。试管法不适用于大量细胞聚集体的微胶囊化。研制了一种特殊的离心机。它操作方便，能有效地对大量细胞聚集体进行微囊化，但在离心机中收集微囊化聚集体时存在一个问题需要解决。

It has been reported that Parkinson's disease can be treated by transplantation of dopamine releasing cells and sever pain of end stage cancer patients can be alleviated by transplanting morphine releasing cells. Immunological reactions are most likely to be the reason for failure when transplanting allogeneic and xenogeneic cells. To overcome this problem, cells are transplanted after they are enclosed into a semipermeable polymer membrane, which must be permeable to small molecules such as oxygen, nutrients and bioactive substances, but impermeable to lymphocytes and immunoglobulins and complement proteins. In addition, it is difficult to find space for a large volume of transplant in central nerve system. Therefore, cen trifugal microencapsulation of cell aggregates was examined to solve these problems. Spherical cell aggregates were suspended into the alginate solution. 0.4 ml of the suspension was over-layed on the top of three layers composed of a 2.5 ml layer of 7 wt% dextran, a 0.5 ml layer of BaCl2 solution and a 0.5 ml layer Of 13 wt% dextran from the top in a 12 ml glass test-tube of 14 mm inner diameter. The test-tube was centrifuged at 170 x g for 10 min to spin the aggregates to the bottom of the tube. This procedure can effectively enclose cell aggregates in microcapsules with a very thin wall without contamination of empty microcapsules.The test-tube method can't be applied to microencapsulation of a large number of cell aggregates. A special centrifuge was developed. It can easily be operate and effectively microencapsulate a large number of cell aggregates, but there is a problem to solve in collecting microencapsulated aggregates from the centrifuge.