Simpson Nicholas E, Khokhlova Nata, Oca-Cossio Jose A, McFarlane Scott S, Simpson Chiab P, Constantinidis Ioannis
The Laboratory for Tissue Engineering, Department of Medicine, Division of Endocrinology, University of Florida, 1600 SW Archer Rd, P.O. Box 100226, Gainesville, FL 32610-0226, USA.
Biomaterials. 2005 Aug;26(22):4633-41. doi: 10.1016/j.biomaterials.2004.11.054. Epub 2005 Jan 13.
The ability to control cell growth is an issue of critical importance for the use of transformed beta-cell lines within a bioartificial pancreas. Such control can be achieved either by entrapping the cells in a biomaterial that can inhibit cell proliferation or by genetically modifying the cells to regulate growth. Integrating tetracycline-off or -on operon systems into murine insulinoma cell lines (betaTC-tet and R7T1, respectively) allows cell growth regulation upon exposure to tetracycline (TC) or its derivative doxycycline (Dox), respectively. However, the effects of this regulatory approach on the long-term phenotypic metabolic and secretory stability of alginate-entrapped cells have yet to be thoroughly investigated. In this study, cultures of betaTC-tet and R7T1 cells entrapped in alginate beads were allowed to grow freely, or were growth-regulated, either at the onset, or after 20 days of growth. The data show that growth regulation of alginate-entrapped cells is achievable with chronic administration of the regulatory compound in a concentration-dependent manner. However, as these cultures age, the amount of insulin released does not always reflect the metabolic and histological characteristics of the cultures. This change, coupled with a loss of glucose stimulated insulin secretion in the Dox treated R7T1 cell line, indicate a phenotypic shift of cells with an activated tet-operon. These observations have implications on the selection and long-term function of three-dimensional bioartificial pancreatic constructs that include conditionally transformed beta-cell lines.
对于在生物人工胰腺中使用转化的β细胞系而言，控制细胞生长的能力是一个至关重要的问题。这种控制可以通过将细胞包埋在能够抑制细胞增殖的生物材料中来实现，或者通过对细胞进行基因改造来调节生长。将四环素关闭或开启操纵子系统整合到小鼠胰岛素瘤细胞系中（分别为βTC-tet和R7T1），分别在暴露于四环素（TC）或其衍生物强力霉素（Dox）时实现细胞生长调节。然而，这种调节方法对藻酸盐包埋细胞的长期表型代谢和分泌稳定性的影响尚未得到充分研究。在本研究中，将包埋在藻酸盐珠中的βTC-tet和R7T1细胞培养物允许自由生长，或者在开始时或生长20天后进行生长调节。数据表明，通过以浓度依赖的方式长期施用调节化合物，可以实现对藻酸盐包埋细胞的生长调节。然而，随着这些培养物的老化，释放的胰岛素量并不总是反映培养物的代谢和组织学特征。这种变化，再加上在Dox处理的R7T1细胞系中葡萄糖刺激的胰岛素分泌丧失，表明具有激活的tet操纵子的细胞发生了表型转变。这些观察结果对包括条件性转化β细胞系的三维生物人工胰腺构建体的选择和长期功能具有影响。
