Publications by authors named "Chungmin Han"

Article Synopsis
  • Extracellular vesicles (EVs) are tiny particles released by cells, which vary in size and make classification challenging; this study employs the coffee ring effect for better size-based separation of these particles.
  • The method successfully differentiated EVs and virus-like particles (VLPs) based on size, revealing unique distribution patterns for tetraspanin markers and confirming these findings through advanced imaging techniques.
  • Overall, the research offers deeper insights into EV heterogeneity and highlights how a cell's origin and development influence the properties of these particles.
View Article and Find Full Text PDF

Extracellular vesicles (EVs) play pivotal roles in intercellular communication and are implicated in numerous physiological and pathological processes. Here, we introduce a quantitative technique using total internal reflection fluorescence microscopy (TIRFm)-based single vesicle analysis (SVA) to assess EV aggregation, a critical factor influencing their biological functionality. Employing two-colored fluorescent recombinant EV mixtures, this method enables precise discrimination between aggregated and non-aggregated EVs.

View Article and Find Full Text PDF

Enveloped viruses pose a significant threat to human health, as evidenced by the recent COVID-19 pandemic. Although current vaccine strategies have proven effective in preventing viral infections, the development of innovative vaccine technologies is crucial to fortify our defences against future pandemics. In this study, we introduce a novel platform called cell-engineered virus-mimetic nanovesicles (VNVs) and demonstrate their potential as a vaccine for targeting enveloped viruses.

View Article and Find Full Text PDF

Background: Variability in decision-making capacity and reward responsiveness may underlie differences in the ability to abstain from smoking. Computational modeling of choice behavior, as with the Hierarchical Drift Diffusion Model (HDDM), can help dissociate reward responsiveness from underlying components of decision-making. Here we used the HDDM to identify which decision-making or reward-related parameters, extracted from data acquired in a reward processing task, contributed to the ability of people who smoke that are not seeking treatment to abstain from cigarettes during a laboratory task.

View Article and Find Full Text PDF

We demonstrate a fluorescence-based nanoparticle tracking analysis (NTA) system for the characterization of both the size and membrane protein expression of individual extracellular vesicles (EVs). A sheet of lasers with four different wavelengths was sequentially shone onto extracellular vesicles according to a preprogrammed schedule, providing scattering images intercalated by three fluorescent images. The presence of extracellular vesicles was tracked frame by frame from scattering images.

View Article and Find Full Text PDF

Extracellular vesicles (EVs) are secreted nano-sized vesicles that contain cellular proteins, lipids, and nucleic acids. Although EVs are expected to be biologically diverse, current analyses cannot adequately characterize this diversity because most are ensemble methods that inevitably average out information from diverse EVs. Here we describe a single vesicle analysis, which directly visualizes marker expressions of individual EVs using a total internal-reflection microscopy and analyzes their co-localization to investigate EV subpopulations.

View Article and Find Full Text PDF

Cell-engineered nanovesicles (CNVs) are considered as an alternative to exosomes, because they can be produced efficiently on a large scale and have been successfully reported in several applied research studies. However, CNVs may originate from various organelles, i.e.

View Article and Find Full Text PDF

Understanding the fundamental roles of brainstem function resulting in proper motor control is critical to motor-rehabilitation after brain injuries. In particular, vestibular and reticular formation nuclei are thought to be associated with spasticity in chronic stroke patients. We used two kinds of stimuli in 10 healthy subjects to activate these nuclei while collecting high-resolution (1.

View Article and Find Full Text PDF

We developed a new type of electroencephalogram (EEG) headset system with comb-shaped electrodes that enables the wearer to quickly don and utilize it in daily life. Two models that can measure EEG signals using up to eight channels have been implemented. The electrodes implemented in the headsets are similar to a comb and are placed quickly by wiping the hair (as done with a comb) using the headset.

View Article and Find Full Text PDF

We report development and characterization of cell-engineered nanovesicles made from mesenchymal stem cells (MSCNVs), which have more than 300 times higher productivity than natural extracellular vesicles (EVs). MSCNVs had similar morphological characteristics to MSCEVs but have molecular characteristics that more resemble MSCs than MSCEVs. MSCNV treatment increased the proliferation and migration of primary skin fibroblasts and showed better effects than treatment using natural MSCEVs.

View Article and Find Full Text PDF

Extracellular vesicles are categorized in subsets according to their biogenesis processes. To facilitate the investigation of subsets, an effective method is needed for isolating subpopulations. The efficacy of existing density and size-based isolation methods is limited, and as a result, the correlation of properties within separated subpopulations is modest.

View Article and Find Full Text PDF

Investigating neural correlates of fine motor control in a magnetically sensitive environment requires special considerations in sensor design. Our application requires measurement of forefinger and thumb forces during precision grip in a relatively low (<; 20 N) force range. This work describes the design, characterization and performance evaluation of an MR-compatible precision grip sensor that independently measures forefinger and thumb forces.

View Article and Find Full Text PDF

Ballistocardiographs (BCGs), which record the mechanical activity of the heart, have been a subject of interest for several years because of their advantages in providing unobtrusive physiological measurements. BCGs could also be useful for monitoring the biological signals of infants without the need for physical confinement. In this study, we describe a physiological signal monitoring bed based on load cells and assess an algorithm to extract the heart rate and breathing rate from the measured load-cell signals.

View Article and Find Full Text PDF

The effects of concentrated fibroblast-conditioned media were tested to determine whether hepatocyte function can be maintained without direct contact between hepatocytes and fibroblasts. Primary rat hepatocytes cultured with a concentrated conditioned media of NIH-3T3 J2 cell line (final concentration of 55 mg/ml) showed significantly improved survival and functions (albumin and urea) compared to those of control groups. They also showed higher expression levels of mRNA, albumin and tyrosine aminotransferase compared to hepatocyte monoculture.

View Article and Find Full Text PDF

Extracellular vesicles (EVs) such as exosomes and microvesicles released from cells are potential biomarkers for blood-based diagnostic applications. To exploit EVs as diagnostic biomarkers, an effective pre-analytical process is necessary. However, recent studies performed with blood-borne EVs have been hindered by the lack of effective purification strategies.

View Article and Find Full Text PDF

Various spheroid formation techniques have been widely developed for efficient and reliable 3-D cell culture research. Although those efforts improved many aspects of spheroid generation, the procedures became complex and also required unusual laboratory equipment. Many recent techniques still involve laborious pipetting steps for spheroid manipulation such as collection, distribution and reseeding.

View Article and Find Full Text PDF

Exosomes/microvesicles are known to shuttle biological signals between cells, possibly by transferring biological signal components such as encapsulated RNAs and proteins, plasma membrane proteins, or both. Therefore exosomes are being considered for use as RNA and protein delivery vehicles for various therapeutic applications. However, living cells in nature secrete only a small number of exosomes, and procedures to collect them are complex; these complications impede their use in mass delivery of components to targeted cells.

View Article and Find Full Text PDF