BACKGROUND:For autoimmune diseases, it is difficult to effectively solve the lack of immunological tolerance in patients by traditional treatments. Mesenchymal stem cells have the biological functions of tissue and organ regeneration and immune regulation. OBJECTIVE:To explore the effects and mechanisms of human umbilical cord-derived mesenchymal stem cells on the development of thymus in nude mice. METHODS:Human umbilical cord-derived mesenchymal stem cells were intraperitoneal y injected into BABL/c nude mice at a dose of 2×106 per mouse. We analyzed the maturation and distribution of thymic epithelial cells in the thymus rudiment of nude mice and the thymopoiesis of this newly developed thymus rudiment;furthermore, we explored the therapeutic effects of human umbilical cord-derived mesenchymal stem cells. RESULTS AND CONCLUSION:Our data showed wel-organized cortex-medul a structure and an obvious improvement in the maturation of thymic epithelial cells in the rudiment. We further demonstrated the improved thymopoiesis and the enhanced export of mature T cells with the T regulatory cells increase in peripheral blood. Furthermore, we found that human umbilical cord-derived mesenchymal stem cells could be engrafted in the thymus and express many cytokines, especial y keratinocyte growth factor which is essential for the thymus development. These findings indicate that a new mechanism of human umbilical cord-derived mesenchymal stem cells can provide a proper microenvironment for the reconstitution and functional maturation of thymus in nude mice, and elicit another insight in terms of therapeutic efficacy of human umbilical cord-derived mesenchymal stem cells in many autoimmune diseases.

Objective:To develop a recombinant protein vaccine based on KPC-2, a drug resistance target in Klebsiella pneumoniae, and evaluate its immunogenicity, protective efficacy and mechanism in a mouse model of pneumonia. Methods:KPC-2 was expressed in Escherichia coli and purified using GST affinity chromatography. A recombinant protein vaccine was prepared with KPC-2 and used to immunize New Zealand rabbits through subcutaneous injection. Serum samples were isolated from cardiac blood and Protein G chromatography was used to purify polyclonal antibodies against KPC-2. Opsonophagocytic killing assay was used to assess the bactericidal activity of the polyclonal antibodies in vitro. Female BALB/c mice were immunized three times with the recombinant protein vaccine, and the titers of specific IgG antibodies in serum were measured by indirect ELISA. One week after the last vaccination, the mice were infected with Klebsiella pneumoniae strain SRT through tracheal intubation, and received a single intravenous dose of meropenem (0.1 mg) 1 h later. The protective efficacy of the KPC-2 recombinant protein vaccine was evaluated by comparing the survival rates, bacterial colonization and histopathological changes between vaccine group and adjuvant group as well as the survival rates between meropenem group and normal saline group. Moreover, the protective efficacy of polyclonal antibodies against KPC-2 was evaluated through passive immunization. Results:The level of specific IgG antibodies in serum was significantly higher in the vaccine group than in the adjuvant group ( t=4.325, P<0.05). The survival rate in the vaccine group was also higher than that of the adjuvant group [70% (7/10) vs 10% (1/10), P<0.05]. Furthermore, lung inflammation was less severe and bacterial burden was reduced in the vaccine group as compared with those of the control group ( t=3.127, P<0.05). Both active and passive vaccination strategies demonstrated strong protective efficacy against Klebsiella pneumoniae infection, and had a synergistic effect when used in combination with antibiotic therapy. The polyclonal antibodies against KPC-2 had bactericidal activity in vitro ( t=5.427, P<0.05). Conclusions:The prepared KPC-2 vaccine has better immunogenicity and protective efficacy. It can induce strong humoral immune responses. This study suggest that drug resistance target may be used as a candidate antigen for future vaccine development.

【Objective】 To analyze the efficacy of different intracavitary operations for calyceal diverticulum calculi, so as to provide reference for the diagnosis and treatment of such disease. 【Methods】 A retrospective analysis of the data of 21 patients with calyceal diverticulum calculi was conducted during Jan. 2015 and Dec.2021. The patients were divided into the retrograde intrarenal surgery (RIRS, n=14) group and percutaneous nephrolithotomy (PCNL, n=7) group. The perioperative data were compared. 【Results】 There was no significant difference in stone load between the RIRS group and PCNL group \[(11.56±4.79) mm vs. (13.06±6.27) mm, P=0.609\].There were significant differences in the thickness of renal parenchyma at the top of the diverticulum \[(10.08±4.81) mm vs. (5.24±2.23) mm, P=0.005\], operation time \[(58.57±19.23) min vs. (88.29±25.28) min, P=0.007\], hospitalization time \[3(1, 5) vs. 12 (5, 7), P=0.023\] days. After operation, there were no significant differences in stone-clearance rate, decrease of hemoglobin, and postoperative complications between the two groups (P>0.05). 【Conclusion】 Both RIRS and PCNL are viable options for treating renal calyceal diverticulum calculi. RIRS has advantages of shorter operation time and hospital stay. PCNL can be an alternative treatment when RIRS is unsuccessful.