In-droplet cell concentration using dielectrophoresis.

Concentrating cells or adjusting the concentration of cells are one of the most fundamental steps in cell biology experiments, and are typically achieved through centrifugation. However this step is challenging to implement in droplet microfluidics. Here we present an in-droplet cell concentrator that operates by first gradually focusing cells inside a droplet to one side of the droplet using negative dielectrophoresis (nDEP), followed by asymmetric droplet splitting using a Y-shaped junction, resulting in two daughter droplets, one of which containing all or most of the cells. The developed platform was first characterized using droplets containing different number of polystyrene (PS) particles and by varying the applied voltages, flow rates, and the width ratios of the droplet splitting microchannels. Using this platform, the volume of one daughter droplet could be reduced up to 84% compared to that of the mother droplet, which resulted in the PS particle concentration to increase by 5.6-fold, with an average recovery rate of 90%. When testing with cells (Chlamydomonas reinhardtii), recovery rates as high as 98% could be achieved while increasing the cell concentration by 5-fold. This technology adds a new capability to droplet microfluidics operation, and can be used for adjusting concentrations of cells in droplets, exchanging solutions in which cells are suspended in droplets (including cell washing steps), and separating cells of different dielectric properties inside droplets, all of which are common steps in conventional cell assays but have been so far difficult to achieve in droplet format.

Impact of body mass index, metabolic health and weight change on incident diabetes in a Korean population.

OBJECTIVE: The aim of this study was to examine an impact of body mass index (BMI) and weight change on the risk of diabetes according to metabolic health status. METHODS: Cohort study of 34,999 Korean men and women 30-59 years of age free of diabetes at baseline were followed-up annually or biennially for an average of 5.1 years. Being metabolically healthy was defined as not having any metabolic syndrome component. RESULTS: During 176,878.6 person-years of follow-up, 889 participants developed diabetes (incidence rate 5.0 per 1000 person-years). Compared to metabolically healthy normal-weight individuals, the adjusted hazard ratios for diabetes in metabolically unhealthy obese and in metabolically healthy obese were 13.7 (95% confidence interval [CI] 9.8-19.0) and 2.7 (95% CI: 1.7-4.3), respectively. The aHR (95% CI) for incident diabetes for weight changes of <-0.9, 0.5 to 2.0, and ≥2.1 kg compared to a weight change of -0.9 to 0.4 kg (reference) were 0.80 (0.66-0.97), 0.99 (0.82-1.20), and 1.24 (1.02-1.49), respectively (P-trend<0.001). CONCLUSIONS: In this large cohort of young and middle age Koreans, metabolic health status, obesity, and weight change were all independently associated with increased incidence of diabetes over 5 years of follow-up.

Histological improvement following administration of autologous bone marrow-derived mesenchymal stem cells for alcoholic cirrhosis: a pilot study.

BACKGROUND: In experimental models, bone marrow-derived mesenchymal stem cells (BM-MSCs) have the capacity to differentiate into hepatocytes and exhibit antifibrotic effects. However, there have been no studies in humans with alcoholic cirrhosis. AIM: The aim of this study was to elucidate the antifibrotic effect of BM-MSCs in patients with alcoholic cirrhosis, as a phase II clinical trial. METHODS: Twelve patients (11 males, 1 female) with baseline biopsy-proven alcoholic cirrhosis who had been alcohol free for at least 6 months were enrolled. BM-MSCs were isolated from each patient's BM and amplified for 1 month, and 5 × 10(7) cells were then injected twice, at weeks 4 and 8, through the hepatic artery. One patient was withdrawn because of ingestion of alcohol. Finally, 11 patients completed the follow-up biopsy and laboratory tests at 12 weeks after the second injection. The primary outcome was improvement in the patients' histological features. RESULTS: According to the Laennec fibrosis system, histological improvement was observed in 6 of 11 patients (54.5%). The Child-Pugh score improved in ten patients (90.9%) and the levels of transforming growth factor-ß1, type 1 collagen and α-smooth muscle actin significantly decreased (as assessed by real-time reverse transcriptase polymerase chain reaction) after BM-MSCs therapy (P < 0.05). No significant complications or side effects were observed during this study. CONCLUSIONS: Bone marrow-derived mesenchymal stem cells therapy in alcoholic cirrhosis induces a histological and quantitative improvement of hepatic fibrosis.

E-cadherin expression in early gastric carcinoma and correlation with lymph node metastasis.

OBJECTIVE: Abnormal expression of E-cadherin plays an important role in the differentiation and progression of gastric carcinoma. However, the relationship between molecular changes in E-cadherin and metastasis in early gastric carcinoma (EGC) is poorly understood. MATERIALS AND METHODS: Sixty cases of EGC with or without lymph node metastasis (30 node-positive cases and 30 node-negative cases) were investigated to evaluate hypermethylation status using bisulfate-MSP and immunohistochemistry using antibody against E-cadherin. RESULTS: Twenty-seven (45.0%) of 60 primary EGCs exhibited methylation in the CpG island of E-cadherin. Abnormal expression of E-cadherin was significantly correlated with patient age, tumor size, Lauren classification, differentiation, and lymph node metastasis. Using multiple logistic regression analysis, two factors were independent, statistically significant parameters associated with lymph node metastasis: abnormal expression of E-cadherin (risk ratio, 2.62; 95% confidence interval, 0.917-7.457; P < 0.05) and lymphatic invasion (risk ratio, 8.11; 95% confidence interval, 1.612-40.766; P < 0.05). CONCLUSION: Our results suggest that methylation of E-cadherin is a frequent, early event in gastric carcinoma progression, and is correlated significantly with downregulated E-cadherin expression. Inactivation of E-cadherin might be involved in metastasis in EGC and play an important role in microscopic differentiation.