Centre for Blood Research, University of British Columbia, Life Sciences Centre, Vancouver, BC, Canada.
Acta Biomater. 2010 Jul;6(7):2631-41. doi: 10.1016/j.actbio.2010.01.031. Epub 2010 Jan 28.
Development of novel approaches for the immunomodulation of donor cells would have significant utility in transfusion and transplantation medicine. Immunocamouflage of cell surfaces by covalently grafted methoxypoly(ethylene glycol) (mPEG) (PEGylation) has emerged as a promising approach. While previous studies demonstrated the in vitro and in vivo efficacy of immunocamouflaged allogeneic blood cells, the biophysical mechanisms of immunoprotection have not been well-defined due to the fragility of intact cells. To overcome this limitation, polystyrene beads (1.2 and 8.0 microm) were used to elucidate the biophysical effects of polymer size, density and linker chemistry on charge camouflage and protein adsorption. These findings were correlated with biological studies using red blood cells and lymphocytes. Charge camouflage of both beads and cells was best achieved with long polymers. However, protein adsorption studies demonstrated an unexpected effect of target size. For 1.2 microm beads, decreased protein adsorption was best achieved with short (2 kDa) polymers whereas long chain (20 kDa) polymers were optimal for 8.0 microm particles. The biophysical findings correlated well with biological immunocamouflage as measured by particle electrophoresis and the inhibition of antibody-antigen (CD3, CD4 and CD28) recognition. Moreover, it was observed that antigen topography (CD28 vs. CD4) was of significance in selecting the appropriate polymer size. The biophysical interactions of PEGylated surfaces and macromolecules involve complex mechanisms dependent on the molecular weight, grafting concentration, target size and surface complexity. Cellular PEGylation strategies must be customized to account for target cell size, membrane complexity and antigen density and height.
开发新型供体细胞免疫调节方法将在输血和移植医学中具有重要的应用价值。通过共价接枝甲氧基聚乙二醇（mPEG）（PEG 化）对细胞表面进行免疫伪装已成为一种很有前途的方法。虽然以前的研究表明免疫伪装的同种异体血细胞在体外和体内的有效性，但由于完整细胞的脆弱性，免疫保护的生物物理机制尚未得到很好的定义。为了克服这一限制，使用聚苯乙烯珠（1.2 和 8.0 µm）来阐明聚合物大小、密度和连接化学对电荷伪装和蛋白质吸附的生物物理影响。这些发现与使用红细胞和淋巴细胞进行的生物学研究相关联。珠粒和细胞的电荷伪装都可以通过长聚合物实现最佳效果。然而，蛋白质吸附研究表明目标大小存在意外的影响。对于 1.2 µm 的珠子，短链（2 kDa）聚合物最适合减少蛋白质吸附，而对于 8.0 µm 的颗粒，长链（20 kDa）聚合物则是最佳选择。生物物理发现与通过粒子电泳和抑制抗体-抗原（CD3、CD4 和 CD28）识别来测量的生物免疫伪装相关性很好。此外，观察到抗原拓扑结构（CD28 与 CD4）在选择合适的聚合物尺寸方面具有重要意义。PEG 化表面和大分子的生物物理相互作用涉及复杂的机制，取决于分子量、接枝浓度、目标大小和表面复杂性。细胞 PEG 化策略必须根据靶细胞大小、膜复杂性和抗原密度和高度进行定制。
