Shen Hong, Hu Yueyue, Saltzman W M
Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA.
Biophys J. 2006 Jul 15;91(2):639-44. doi: 10.1529/biophysj.105.077404. Epub 2006 Apr 21.
DNA represents a promising therapeutic and prophylactic macromolecule in treating genetic diseases, infectious diseases and cancers. The therapeutic potential of DNA is directly related to how DNA transports within the targeted tissue. In this study, fluorescence photobleaching recovery was used to examine the diffusion of plasmid DNAs with various size (2.7-8.3 kb), topology, and in the presence of transfection reagents in mucus. We observed that DNAs diffused slower when size of DNAs increased; supercoiled DNAs diffused faster than linear ones; mucus did not reduce the diffusion of linear DNAs but retarded the diffusion of supercoiled DNAs. Diffusion data were fitted to models of a polymer chain diffusing in gel systems. Diffusion of linear DNAs in mucus were better described by the Zimm model with a scaling factor of -0.8, and supercoiled DNAs showed a reptational behavior with a scaling factor of -1.3. Based on the Zimm model, the pore size of bovine mucus was estimated and agreed well with previous experimental data. In the presence of transfection reagents, e.g., liposomes, the diffusion of DNAs increased by a factor of 2 in mucus. By using bovine mucus as a model system, this work suggests that DNA size, topology, and the presence of transfection reagents may affect the diffusion of DNA in tissues, and thus the therapeutic effects of DNA.
在治疗遗传疾病、传染病和癌症方面，DNA是一种很有前景的治疗和预防大分子。DNA的治疗潜力与DNA在靶组织内的转运方式直接相关。在本研究中，利用荧光光漂白恢复技术来检测不同大小（2.7-8.3 kb）、拓扑结构的质粒DNA以及在转染试剂存在下在黏液中的扩散情况。我们观察到，随着DNA大小增加，其扩散速度减慢；超螺旋DNA比线性DNA扩散得更快；黏液不会降低线性DNA的扩散，但会阻碍超螺旋DNA的扩散。扩散数据被拟合到聚合物链在凝胶系统中扩散的模型。线性DNA在黏液中的扩散用缩放因子为-0.8的齐姆模型能更好地描述，超螺旋DNA表现出缩放因子为-1.3的蠕动行为。基于齐姆模型，估算了牛黏液的孔径，与先前的实验数据吻合良好。在转染试剂（如脂质体）存在的情况下，DNA在黏液中的扩散增加了2倍。通过使用牛黏液作为模型系统，这项工作表明DNA大小、拓扑结构以及转染试剂的存在可能会影响DNA在组织中的扩散，进而影响DNA的治疗效果。
