Publications by authors named "Jiwan Choi"

Technology has been developed to monitor the differentiation process of human mesenchymal stem cells (hMSCs) into hepatocyte-like cells (HLCs) and hepatic progenitor cells (HPCs). These cell lineages, differentiated from MSCs, are ethically unproblematic and are gaining attention as promising cell-based therapies for treating various liver injuries. High-sensitivity, label-free, real-time monitoring technologies integrated with artificial intelligence have been used to evaluate and optimize cell differentiation for enhancing the efficiency of cell therapy delivery.

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BRAF-mutated colorectal cancer correlates with poor prognosis and limited response to standard treatments. Combining immune checkpoint inhibitors with BRAF/MEK inhibitors shows promise against BRAF-mutant melanoma in both preclinical and clinical trials. Therefore, we hypothesized that the treatment would be effective against BRAF-mutant colorectal cancer.

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Background & Aims: The global pandemic caused by the highly contagious SARS-CoV-2 virus led to the emergency approval of COVID-19 vaccines to reduce rising morbidity and mortality. However, limited research exists on evaluating the impact of these vaccines on immunocompromised individuals, such as recipients of living donor liver transplantation, highlighting the need for further studies to better understand their effectiveness in this specific population.

Methods: From June 2021, we followed up on the effectiveness of the vaccine for patients taking immunosuppressive drugs after living-donor liver transplantation (LDLT).

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Hepatitis C virus (HCV) is a pathogen that causes cirrhosis and hepatocellular carcinoma through chronic hepatitis C. This study focused on the anti-HCV activity of a 70% ethanol extract of Nakai (KKE) and its bioactive chemical constituent(s). The KKE and its -butanol (-BuOH) fraction induced a significant reduction in HCV RNA levels without inducing cytotoxicity.

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Article Synopsis
  • Human mesenchymal stem cells from umbilical cord (hUCM-MSCs) show potential for tissue regeneration, but efficient differentiation methods for these cells into specific types like hepatocyte-like cells (HLCs) need improvement.
  • Researchers utilized a ROCK inhibitor called fasudil and gelatin to enhance the differentiation efficiency of hUCM-MSCs into HLCs, while monitoring gene expression and organelle function throughout the process.
  • The study found that fasudil promoted endoderm gene expression but excessive lipid droplet formation hindered differentiation; using high-viscosity gelatin minimized lipid droplets and enhanced mitochondrial function, leading to better outcomes in forming hepatoblasts.
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Article Synopsis
  • The study focuses on patient-derived induced pluripotent stem cells (iPSCs) from Alzheimer's disease (AD) patients to explore mitochondrial DNA (mtDNA) mutations and their effects on neuronal function.
  • Researchers found that iPSCs from AD patients had significantly more mtDNA mutations than those from umbilical cord blood, affecting mitochondrial performance and contributing to β-amyloid (Aβ) accumulation.
  • The results highlight the importance of screening mtDNA mutations in iPSC lines, as these mutations could lead to mitochondrial dysfunction and inform potential therapies for Alzheimer's disease.
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Diabetes mellitus (DM) is a serious disease in which blood sugar levels rise abnormally because of failed insulin production or decreased insulin sensitivity. Although many studies are being conducted for the treatment or early diagnosis of DM, it is not fully understood how mitochondrial genome (mtDNA) abnormalities appear in patients with DM. Here, we induced iPSCs from fibroblasts, PBMCs, or pancreatic cells of three patients with type 2 DM (T2D) and three patients with non-diabetes counterpart.

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Haploidy is naturally observed in gametes; however, attempts of experimentally inducing haploidy in somatic cells have not been successful. Here, we demonstrate that the replacement of meiotic spindles in mature metaphases II (MII) arrested oocytes with nuclei of somatic cells in the G0/G1 stage of cell cycle results in the formation of de novo spindles consisting of somatic homologous chromosomes comprising of single chromatids. Fertilization of such oocytes with sperm triggers the extrusion of one set of homologous chromosomes into the pseudo-polar body (PPB), resulting in a zygote with haploid somatic and sperm pronuclei (PN).

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Background: Amnion-derived mesenchymal stem cells (AM-MSCs) are an attractive source of stem cell therapy for patients with irreversible liver disease. However, there are obstacles to their use due to low efficiency and xeno-contamination for hepatic differentiation.

Methods: We established an efficient protocol for differentiating AM-MSCs into hepatic progenitor cells (HPCs) by analyzing transcriptome-sequencing data.

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Mitochondria are essential organelles that are not only responsible for energy production but are also involved in cell metabolism, calcium homeostasis, and apoptosis. Targeting mitochondria is a key strategy for bacteria to subvert host cells' physiology and promote infection. targets mitochondria directly.

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Human liver-derived stem cells (hLD-SCs) have been proposed as a possible resource for stem cell therapy in patients with irreversible liver diseases. However, it is not known whether liver resident hLD-SCs can differentiate toward a hepatic fate better than mesenchymal stem cells (MSCs) obtained from other origins. In this study, we compared the differentiation ability and regeneration potency of hLD-SCs with those of human umbilical cord matrix-derived stem cells (hUC-MSCs) by inducing hepatic differentiation.

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Poor survival of human pluripotent stem cells (hPSCs) following freezing, thawing, or passaging hinders the maintenance and differentiation of stem cells. Rho-associated kinases (ROCKs) play a crucial role in hPSC survival. To date, a typical ROCK inhibitor, Y-27632, has been the primary agent used in hPSC research.

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Natural killer (NK) cells are key effectors in cancer immunosurveillance and can be used as a prognostic biomarker in diverse cancers. Nonetheless, the role of NK cells in pancreatic cancer (PC) remains elusive, given conflicting data on their association with disease prognosis. In this study, using conventional K562 target cells and complementary engineered target cells providing defined and synergistic stimulation for NK cell activation, a correlation between impaired NK cell cytotoxic degranulation and PC progression was determined.

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This study identified 8-azaguanine (8-AG) as a novel immunomodulatory drug (IMiD) through a high-throughput screen of the Preswick Chemical Library in a model of human NK cell cytotoxicity against blood cancer cells. 8-AG, originally developed as an antineoplastic agent, significantly increased the cytotoxicity of NK cells and was superior in this activity to previously known IMiDs, such as fluoxetine and amphotericin B, identified from the same library. IFN-γ expression was also slightly increased by 8-AG.

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Immunomodulatory drugs (IMiDs) present one example of immunomodulatory agents that improve cancer immunotherapy. Based on the cytotoxic activity of natural killer (NK) cells against cancer cells, a high throughput screening method for the identification of novel immunomodulatory molecules with the potential to stimulate NK cell cytotoxicity against cancer cells was designed and tested using an approved drug library. Among the primary hit compounds, the anti-fungal drug amphotericin B (AMP-B) increased the cytotoxicity of NK cell line and human primary NK cells in a direct manner.

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