Gene vectors are of great importance in gene therapy.Research on non-viral gene vectors has become the most urgent issue as viral gene vectors have shown a series of safety problems during clinical application.Chitosan is one of the best potential non-viral gene vectors because of its excellent physico-chemical and biological properties.In recent years,a lot of works have been done on chitosan and its modification for gene delivery,and valuable progresses have been achieved.In this paper,recent progresses in chitosan and its modified derivates for gene delivery are reviewed in temls of size,stability,specific targeting ability and gene transfection efficiency of the chitosan/gene complex.

Objective:To analyze the effect of active lymphocyte immunotherapy (LIT) in patients with recurrent implantation failure (RIF), as well as its influence on serum galectin-3, galectin-1, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in cervical secretions.Methods:From January 2018 to March 2019, 144 patients with in-vitro fertilization and embryo transfer (IVF-ET) admitted to the First People′s Hospital of Tianmen were enrolled. Among them, there were 66 patients with RIF (RIF group) and 78 cases without RIF (non-RIF group). First, the differences of serum galectin-3, galectin-1, TNF-α and IL-6 in cervical secretions were compared between the two groups. Subsequently, the patients with RIF were treated with LIT, and the therapeutic effects were observed. The differences of the above indicators before and after treatment were compared.Results:The levels of serum galectin-1, galectin-3 and cervical secretion IL-6 in patients with RIF were lower than those in non-RIF patients [ovulation day: (35.94 ± 3.91) μg/L vs. (39.26 ± 3.75) μg/L, (53.10 ± 5.91) μg/L vs. (57.68 ± 6.87) μg/L, (73.13 ± 16.69) μg/L vs. (90.98 ± 16.25) μg/L; after ovulation for 6 d: (43.13 ± 4.53) μg/L vs. (48.95 ± 6.23) μg/L, (68.61 ± 7.70) μg/L vs. (72.25 ± 7.94) μg/L, (81.11 ± 16.02) μg/L vs. (91.21 ± 18.13) μg/L], the level of TNF-α in cervical secretion was higher than that in non-RIF patients [ovulation day: (13.33 ± 1.76) μg/L vs. (10.20 ± 1.74) μg/L; after ovulation for 6 d: (12.17 ± 1.64) μg/L vs. (9.36 ± 1.84) μg/L], and the differences were statistically significant ( P<0.05). After LIT treatment, the embryo implantation rate was 25.45% (42/165), the clinical pregnancy rate was 48.48% (32/66), and the abortion rate was 9.38% (3/32). After treatment, the serum galectin-1, galectin-3, cervical secretion IL-6 levels were higher than those before treatment, cervical secretions TNF-α levels were lower than before treatment, and the differences were statistically significant ( P<0.05). Conclusions:The levels of serum galectin-1, galectin-3, cervical secretions TNF-α, IL-6 in patients with RIF are different from those in non-RIF patients. LIT treatment can reduce the difference of these indicators and has certain treatment effect for patients with RIF.