[Research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair].

How to promote high-quality wound healing is a common problem for plastic surgery and burn physicians. In recent years, numerous animal studies have demonstrated that mesenchymal stem cell-derived exosomes promote wound repair through multiple mechanisms and are promising cell-free therapeutic agents with broad prospect of application. How to enhance the therapeutic efficacy of exosomes, optimize their drug delivery strategy, and improve their biological properties are the challenges to be overcome in order to move from basic research to clinical application of exosome therapy for wound repair. This article focuses on methods to improve the wound repair potential of mesenchymal stem cell-derived exosomes, and reviews the recent research advances on improving the therapeutic efficacy of mesenchymal stem cell-derived exosomes in wound repair from three aspects, including pretreatment of parental mesenchymal stem cells, hydrogel bio-scaffold loaded with exosomes, and engineered exosomes, to provide a reference for further clinical studies.

[Analysis of mortality trend and characteristic of chronic obstructive pulmonary disease among residents in China from 2004 to 2020].

Objective: To analyze the mortality trend and characteristics of chronic obstructive pulmonary disease (COPD) among residents in China from 2004 to 2020. Methods: From the area, gender, region, and age dimensions, the Joinpoint regression model was used to analyze the trend of COPD mortality rate from 2004 to 2020, extracted from the China Death Surveillance Dataset. Results: From 2004 to 2020, the mortality rate and age-adjusted mortality rate of COPD showed a downward trend (AAPC=-3.68%, P<0.001; AAPC=-7.27%, P<0.001), which were consistent with urban and rural subpopulations (mortality rate: AAPC=-3.62%, P=0.009, AAPC=-3.23%, P=0.014; age-adjusted mortality rate: AAPC=-7.26%, P<0.001, AAPC=-6.78%, P<0.001). The mortality rate of COPD in rural was higher than that of urban subpopulations (P<0.001). Also, the mortality rate and age-adjusted mortality rate of COPD showed a downward trend in males and females (mortality rate: AAPC=-3.00%, P<0.001, AAPC=-4.37%, P<0.001; age-adjusted mortality rate: AAPC=-6.73%, P<0.001, AAPC=-8.11%, P<0.001), and the COPD mortality rate for male was generally higher than female (P<0.001). Meanwhile, the mortality rate of COPD in eastern, central and western regions also showed a downward trend (AAPC=-3.87%, P<0.001; AAPC=-3.12%, P<0.001; AAPC=-1.37%, P=0.001), and western regions were significantly higher than that in central (P<0.001) and eastern (P<0.001) regions. The mortality rate of COPD in the age group of Chinese people showed a downward trend in<45, 45-59, and≥60 years groups (AAPC=-9.48%, P<0.001; AAPC=-9.03%, P<0.001; AAPC=-5.91%, P<0.001). Among them,≥60 years groups was significantly higher than that in<45 (P<0.001) and 45-59 (P<0.001) years groups, and the decline rate was slowest. Conclusion: In China, the mortality rate of COPD decreases from 2004 to 2020, and more efforts are needed to reduce COPD mortality, especially in western regions, rural populations, males and the elderly.

Dynamic study of calcium phosphate formation on porous HA/TCP ceramics.

Bone-like apatite formation on porous calcium phosphate ceramics was investigated in static simulated body fluid (SBF) and dynamic SBF at different flowing rates. The results of a 14-day immersion in static SBF showed that the formation of bone-like apatite occurred both on the surface and in the pores of the samples. When SBF flowed at the physiological flow rate in muscle (2 ml/100 ml.min), bone-like apatite could be detected only in internal surface of the pores of samples. The result that bone-like apatite formation could only be found in the pores when SBF flowed at physiological flow rate was consistent with that of porous calcium phosphate ceramics implanted in vivo: osteoinduction was only detected inside the pores of the porous calcium phosphate ceramics. This result implicates that the bone-like apatite may play an important role in the osteoinduction of Ca-P materials. The dynamic model used in this study may be better than usually used static immersion model in imitating the physiological condition of bone-like apatite formation. Dynamic SBF method is very useful to understand bone-like apatite formation in vivo and the mechanism of ectopic bone formation in calcium phosphate ceramics.

Dynamic study of calcium phosphate formation on porous HA/TCP ceramics.

Bone-like apatite formation on porous calcium phosphate ceramics was investigated in static simulated body fluid (SBF) and dynamic SBF at different flowing rates. The results of a 14-day immersion in static SBF showed that the formation of bone-like apatite occurred both on the surface and in the pores of the samples. When SBF flow at the physiological flow rate in muscle (2 ml/100 ml min1), bone-like apatite could be detected only in internal surface of the pores of samples. The result that bone-like apatite formation could only be found in the pores when SBF flown at physiological flow rate was consistent with that of porous calcium phosphate ceramics implanted in vivo: osteoinduction was only detected inside the pores of the porous calcium phosphate ceramics. This result implicates that the bone-like apatite may play an important role in the osteoinduction of Ca-P materials. The dynamic model used in this study may be better than usually used static immersion model in imitating the physiological condition of bone-like apatite formation. Dynamic SBF method is very useful to understand bone-like apatite formation in vivo and the mechanism of ectopic bone formation in calcium phosphate ceramics.

[Effect of -6 degrees head-down-bed-rest on human cellular immune function].

OBJECTIVE: To observe the effect of -6 degrees head-down bed-rest on proliferation of lymphocyte and production of certain cytokines. METHODS: 6 healthy young men served as the subjects. Peripheral blood lymphocyte was assayed 1d prior to and on the 3rd day and 6th day of bed rest. RESULTS: The production of IFN-alpha on the 3rd day was markedly decreased (P < 0.05), but killing activity of NK was significantly enhanced (P < 0.05), production of IFN-gamma and expression of IL-2 receptor were all slightly reduced. Both production of IFN-alpha and killing activity of NK resumed to the control level on the 6th day, production of IFN-r and CD25 were significantly lowered (P < 0.05) on the 6th day, a lymphocyte proliferation and production of IL-2 were gradually decreased with time, but production of IL-6 was gradually increased. CONCLUSION: -6 degrees head-down bed-rested has certain effect on cellular immune function in man.

[Studies on negative conversion of schistosome-infected snails in mountainous region of Yunnan].

The monthly cercaria shedding of 90 artificially infected Oncomelania snails was observed under a field condition in mountainous region, Shitoudi Village, Weishan County, Yunnan Province. The results showed that 20% of teh snails shed cercaria monthly, 42.2% could shed irregularly and 37.8% stopped releasing cercariae after several times of shedding. Final direction of the snails showed that none cercaria or sporocyst could be found in part of the snails. A total of 304 naturally infected snails were observed individually every month. Samples were taken each month from the snails which did not shed cercaria, then dissected and examined. The negative conversion rate was calculated in the second, third, fourth, fifth and sixth month after the first shedding, which were 36.1, 50.0, 41.0, 39.8 and 2.6% respectively.