Secretome of Stem Cells: Roles of Extracellular Vesicles in Diseases, Stemness, Differentiation, and Reprogramming

Increasing evidence suggests that stem cells or stem cell-derived cells may contribute to tissue repair, not only by replacing lost tissue but also by delivering complex sets of secretory molecules, called secretomes, into host injured tissues. In recent years, extracellular vesicles (EVs) have gained much attention for their diverse and important roles in a wide range of pathophysiological processes. EVs are released from most types of cells and mediates cell–cell communication by activating receptors on target cells or by being taken up by recipient cells. EVs, including microvesicles and exosomes, encapsulate and carry proteins, nucleic acids, and lipids in the lumen and on the cell surface. Thus, EV-mediated intercellular communication has been extensively studied across various biological processes. While a number of investigations has been conducted in different tissues and body fluids, the field lacks a systematic review on stem cell-derived EVs, especially regarding their roles in stemness and differentiation. Here, we provide an overview of the pathophysiological roles of EVs and summarize recent findings focusing on EVs released from various types of stem cells. We also highlight emerging evidence for the potential implication of EVs in self-renewal, differentiation, and reprograming and discuss the benefits and limitations in translational approaches.

Wireless navigation of pigeons using polymer-based fully implantable stimulator: A pilot study using depth electrodes.

A polymer-based implantable stimulator for wirelessly navigating pigeons was conceptually suggested and a pilot study using depth electrodes was conducted. In this study, depth electrodes based on liquid crystal polymer (LCP) with eight channels were designed and fabricated. Electrochemical impedance spectrum (EIS) assessments were performed to measure impedances of the electrodes. The average value of the measured impedances was 16.8∠15.8 ° kµ. The electrodes were then advanced to a target nucleus (formatio reticularis medialis mesencephalic, FRM) of a pigeon to prove their in vivo feasibilities. Biphasic current pulses were generated by a custom-made stimulator and delivered to the electrodes to stimulate the FRM electrically. Pulses with an amplitude level of 0.567 µA, a rate of 58.0 Hz, and a duration of 1.00 ms were applied with inter-stimulus intervals of three minutes. Turning and circling behaviors were consistently shown when the FRM was stimulated. The feasibilities of the electrodes were proved in both in vitro and in vivo tests, as a pilot study for the suggested scheme. Finally, several discussions of the assessments and extensions for a fully implantable stimulator were described.

Normal antistreptolysin O titers of children by age group in the Gyeonggi-Incheon region / 소아과

PURPOSE: Measurement of antistreptolysin O (ASO) is often necessary to confirm a clinical diagnosis of recent streptococcal infection, especially in patients suspected of rheumatic fever and acute glomerulonephritis. Standard normal ranges for ASO should be established locally for each age group. We analyzed ASO to determine the upper limit of normal (ULN) ASO in children in the Gyeonggi-Incheon area. METHODS: ASO in normal individual concentrations were measured quantitatively by nephelometry on sera from 753 children (Male:381, Female:372). ULN were determined by separating the upper 20% from the lower 80% of the group (80 percentile). RESULTS: The mean ASO concentration calculated in a total cases was 149.9+/-7.2 IU/mL. The ASO concentration in neonates was 83.4+/-10.7 IU/mL, and lowest in the 1 year of age group, 26.7+/-6.6 IU/ mL, and increased to 318.0+/-33.2 IU/mL gradually in the 9 years of age group. Thereafter, ASO concentration decreased. The ULN for neonates was 122 IU/mL, for 0-3 years, 40 IU/mL; for 4-6 years, 113 IU/ mL; for 7-9 years, 489 IU/mL; for 10-19 years, 433 IU/mL; for 20-29 years, 122 IU/mL. CONCLUSION: The age-specific ULN for children in the Gyeonggi-Incheon area were determined. The distribution of ASO concentration according to age groups was different from previous reports. These results should be of clinical value to physicians to interprete the ASO results of their patients.