心房颤动(AF)使心房发生电重构,主要表现为心房有效不应期(AERP)缩短、AERP频率适应性降低、不应期离散度增大和传导速度减慢,有利于AF发生和维持.AF引起的电重构是可逆的,多数情况下在转复窦性心律后数天内,电生理特性恢复正常,但电转复后心房收缩功能降低(收缩功能重构)的恢复远远迟于电重构的恢复.研究显示,除电重构外,AF时心房肌结构发生明显改变,即出现结构重构,主要表现为心房肌细胞肥大、肌原纤维溶解和缺失、核周糖原聚集以及线粒体异常等,可被称为程序性细胞存活(programmed cell survival).这种结构改变属心房肌的自我保护性适应,使得心房肌细胞能够在缺血或被动延展等病理情况下存活,因此,AF转复后尽管有所延迟,心房收缩功能仍能够部分甚至完全恢复.

AIM: To determine survival and differentiation of cultured neural stem cells (NSCs) into viable and functional neurons upon transplantation into mice brain of MPTP-induced Parkinson disease (PD). METHODS: Mouse model of PD was established with two subcutaneous (sc) injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 40 mg/kg) twice, 16 h apart. NSCs isolated from rat embryo midbrain were cultured in clonal density.After labeled with 5-bromo-2'-deoxyuridine (BrdU), the NSCs were transplanted into the uni- or bi-lateral striatum of PD mouse. Tyrosine hydroxylase (TH) immunofluorescence was used to evaluate the toxicity of MPTP on theneural cells in the substantia nigra. Immunohistology and laser confocal microscope were used to detect the survival and differentiation of transplanted NSCs. RESULTS: The cultured NSCs generated neurospheres and differentiated into neuron and astrocyte. It indicated that the cultured NSCs were multipotent and self-renewal in vitro.TH-positive neural cells were significantly reduced in the substantia nigra. Immunohistology showed that the uni- or bi-lateral transplanted NSCs survived in the brain of PD model mouse. Laser confocal microscope indicated that some transplanted NSCs could properly differentiate into targeted TH-positive neural cells in vivo. CONCLUSION:The transplanted multipotent NSCs could survive and differentiate into functional dopamine neurons.