ABSTRACT
BACKGROUND: Liver fibrosis has higher morbidity and mortality. Activation and proliferation of hepatic stellate cells is a key link in the progression of liver fibrosis. At present, there are still no effective anti-fibrosis agents targeting single links or targets.OBJECTIVE: To analyze the effect of human adipose stem cells derived exosomes on rats with liver fibrosis induced by carbon tetrachloride. METHODS: Human adipose stem cells were obtained from healthy people by enzyme dissolution method. After in vitro culture, human adipose stem cells derived exosomes were obtained by multiple ultrafiltration. Different concentrations of exosomes were used to treat the hepatic stellate cells activated by transforming growth factor β1. The human adipose stem cells activated by transforming growth factor β1 were treated with different concentrations of exosomes. The expression of α-smooth actin in the cells was detected by quantitative PCR, and the growth and apoptosis of activated hepatic stellate cells were detected by CCK-8 and flow cytometry respectively. Rat models of liver fibrosis were established by intraperitoneal injection of carbon tetrachloride and treated by tail vein injection of exosomes. Rat liver function, serum levels of type III procollagen and type IV collagen, and Ishak score were determined. Semi-quantitative analysis of liver fibrosis was performed. The expression levels of tissue inhibitor of matrix metalloproteinase-1, matrix metalloproteinase 9 and α-smooth actin in liver tissue were measured by immunofluorescence method. The study protocol was approved by the Animal Ethics Committee and Medical Ethics Committee, Tongji University, China in January, 2017. RESULTS AND CONCLUSION: Human adipose stem cells derived exosomes inhibited the proliferation of activated hepatic stellate cells. The possible mechanism is to inhibit the proliferation of activated macrophages, reduce the production of collagen fibers, α-smooth actin actin, and tissue inhibitor of matrix metalloproteinase-1, and to increase the expression of matrix metalloproteinase 9. These findings suggest that exosomes can be used to treat carbon tetrachloride induced liver fibrosis.
ABSTRACT
BACKGROUND: It has been believed mesenchymal stem cells (MSCs) play a role in treatment through paracrine mechanism. Various side effects such as embolism, tumorigenesis and immunological reaction caused by direct injection of MSCs can be avoided by extracting MSC lysate. However, there is a larger difference in current collection methods and standards of MSC lysate. OBJECTIVE: To compare repeated freeze-thaw and ultrasonication for the collection of lysate of MSCs. METHODS: Adipose-derived mesenchymal stem cells (ADMSCs) were isolated from the abdominal subcutaneous fat of healthy individuals, and purified with adherence screening method, followed by in vitro amplification using fetal bovine serum medium. The common surface makers of these cells were tested by flow cytometry (1×109, 2×109, 4×109/L). Repeated freeze-thaw and ultrasonication were employed for cell cytoclasis at three different densities respectively in saline and double distilled water, and a comprehensive comparison was performed on cytoclasis rate and the content of protein in cell lysate between the two methods. RESULTS AND CONCLUSION: (1) ADMSCs obtained from in vitro isolated human adipose tissue grew in a swirl or radial pattern with a homogenous size and neat arrangement. CD44, CD90, CD105 and other commonly used surface markers were highly expressed. (2) The study for optimization of lysate collection revealed that the higher cell density implicated a longer time for cell wall disruption and cytoclasis, as well as significantly increased cytoclasis rate. (3) BCA protein assay showed that the highest content of protein was obtained in saline solvent using ultrasonication method. Comprehensive analysis on the results leads to a conclusion that ultrasonication method with saline as the solvent is the optimized method for extraction of ADMSCs lysate, and the cell concentration of less than 4×109/L is recommended.