Charge-Based Isolation of Extracellular Vesicles from Human Plasma.

Extracellular vesicles (EVs) have garnered significant attention due to their potential applications in disease diagnostics and management. However, the process of isolating EVs, primarily from blood samples, is still suboptimal. This is mainly attributed to the abundant nature of soluble proteins and lipoproteins, which are often separated together with EVs in the end products of conventional isolation methods. As such, we devise a single-step charge-based EV isolation method by utilizing positively charged beads to selectively remove negatively charged major impurities from human plasma via electrostatic interaction. By carefully controlling the buffer pH, we successfully collected EVs from undesired plasma components with superior purity and yield compared to conventional EV collection methods. Moreover, the developed process is rapid, taking only about 20 min for overall EV isolation. The charge-based isolation can ultimately benefit the EV-based liquid biopsy field for the early diagnosis of various diseases.

Current Status of Cardiovascular Disease According to the Duration of Hypertension in Korean Adults.

Background: Today, medical technology and healthcare advances have led to an increased life expectancy; however, the prevalence of chronic diseases such as hypertension, diabetes mellitus, stroke, and cardiovascular events is continuously rising. In particular, hypertension is a crucial factor in cardiovascular and cerebrovascular diseases, and it is known that prevention and management are essential. Objectives: This study investigates the prevalence and management of hypertension in Korean adults and evaluates its correlation with the risk of cardiovascular disease (CVD) and stroke. Method: The Korean National Health and Nutritional Examination Survey (KNHANES) database was utilized for this study (https://knhanes.cdc.go.kr). The subjects of this survey were sampled to represent the entire population of Korea. The study aims to assess the risk of CVD and stroke according to the duration of hypertension. We also examined the impact of hypertension control on the risk of CVD and stroke. This study is a retrospective cross-sectional study, so future risks cannot be assessed, but only the disease status at the same time point. Results: A total of 61,379 subjects were enrolled in the KNHANES database, representing Korea's population of 49,068,178 subjects. The prevalence of hypertension was 25.7% (9,965,618 subjects) of the total population. The prevalence of hypertension increased rapidly with the age of the population. As the duration of hypertension increased, the risks of CVD and stroke also increased. When hypertension lasts longer than 20 years, ischemic heart disease, myocardial infarction, and stroke prevalence were 14.6%, 5.0%, and 12.2%, respectively. However, achieving a target blood pressure (BP) goal below 140/90 mmHg reduced the risk of all CVD and stroke by nearly half. Nevertheless, fewer than two-thirds of patients in Korea with hypertension achieved this targeted blood pressure goal. Conclusions: Our study confirmed that the prevalence of hypertension in Korean adults was higher than a quarter but also showed that the risk of CVD and stroke was significantly reduced by achieving optimal blood pressure control. Based on these results, policy efforts are needed to reach the target BP and improve the treatment rates for hypertension in Korea.

OCT4-induced oligodendrocyte progenitor cells promote remyelination and ameliorate disease.

The generation of human oligodendrocyte progenitor cells (OPCs) may be therapeutically valuable for human demyelinating diseases such as multiple sclerosis. Here, we report the direct reprogramming of human somatic cells into expandable induced OPCs (iOPCs) using a combination of OCT4 and a small molecule cocktail. This method enables generation of A2B5+ (an early marker for OPCs) iOPCs within 2 weeks retaining the ability to differentiate into MBP-positive mature oligodendrocytes. RNA-seq analysis revealed that the transcriptome of O4+ iOPCs was similar to that of O4+ OPCs and ChIP-seq analysis revealed that putative OCT4-binding regions were detected in the regulatory elements of CNS development-related genes. Notably, engrafted iOPCs remyelinated the brains of adult shiverer mice and experimental autoimmune encephalomyelitis mice with MOG-induced 14 weeks after transplantation. In conclusion, our study may contribute to the development of therapeutic approaches for neurological disorders, as well as facilitate the understanding of the molecular mechanisms underlying glial development.

GCC2 as a New Early Diagnostic Biomarker for Non-Small Cell Lung Cancer.

No specific markers have been identified to detect non-small cell lung cancer (NSCLC) cell-derived exosomes circulating in the blood. Here, we report a new biomarker that distinguishes between cancer and non-cancer cell-derived exosomes. Exosomes isolated from patient plasmas at various pathological stages of NSCLC, NSCLC cell lines, and human pulmonary alveolar epithelial cells isolated using size exclusion chromatography were characterized. The GRIP and coiled-coil domain-containing 2 (GCC2) protein, involved in endosome-to-Golgi transport, was identified by proteomics analysis of NSCLC cell line-derived exosomes. GCC2 protein levels in the exosomes derived from early-stage NSCLC patients were higher than those from healthy controls. Receiver operating characteristic curve analysis revealed the diagnostic sensitivity and specificity of exosomal GCC2 to be 90% and 75%, respectively. A high area under the curve, 0.844, confirmed that GCC2 levels could effectively distinguish between the exosomes. These results demonstrate GCC2 as a promising early diagnostic biomarker for NSCLC.

Thymidine decreases the DNA damage and apoptosis caused by tumor-treating fields in cancer cell lines.

BACKGROUND: Tumor-treating fields (TTFields) is an emerging non-invasive cancer-treatment modality using alternating electric fields with low intensities and an intermediate range of frequency. TTFields affects an extensive range of charged and polarizable cellular factors known to be involved in cell division. However, it causes side-effects, such as DNA damage and apoptosis, in healthy cells. OBJECTIVE: To investigate whether thymidine can have an effect on the DNA damage and apoptosis, we arrested the cell cycle of human glioblastoma cells (U373) at G1/S phase by using thymidine and then exposed these cells to TTFields. METHODS: Cancer cell lines and normal cell (HaCaT) were arrested by thymidine double block method. Cells were seeded into the gap of between the insulated wires. The exposed in alternative electric fields at 120 kHz, 1.2 V/cm. They were counted the cell numbers and analyzed for cancer malignant such as colony formation, Annexin V/PI staining, γH2AX and RT-PCR. RESULTS: The colony-forming ability and DNA damage of the control cells without thymidine treatment were significantly decreased, and the expression levels of BRCA1, PCNA, CDC25C, and MAD2 were distinctly increased. Interestingly, however, cells treated with thymidine did not change the colony formation, apoptosis, DNA damage, or gene expression pattern. CONCLUSIONS: These results demonstrated that thymidine can inhibit the TTFields-caused DNA damage and apoptosis, suggesting that combining TTFields and conventional treatments, such as chemotherapy, may enhance prognosis and decrease side effects compared with those of TTFields or conventional treatments alone.

A Proteomic Approach to Understand the Clinical Significance of Acute Myeloid Leukemia-Derived Extracellular Vesicles Reflecting Essential Characteristics of Leukemia.

Extracellular vesicle (EV) proteins from acute myeloid leukemia (AML) cell lines were analyzed using mass spectrometry. The analyses identified 2450 proteins, including 461 differentially expressed proteins (290 upregulated and 171 downregulated). CD53 and CD47 were upregulated and were selected as candidate biomarkers. The association between survival of patients with AML and the expression levels of CD53 and CD47 at diagnosis was analyzed using mRNA expression data from The Cancer Genome Atlas database. Patients with higher expression levels showed significantly inferior survival than those with lower expression levels. ELISA results of the expression levels of CD53 and CD47 from EVs in the bone marrow of patients with AML at diagnosis and at the time of complete remission with induction chemotherapy revealed that patients with downregulated CD53 and CD47 expression appeared to relapse less frequently. Network model analysis of EV proteins revealed several upregulated kinases, including LYN, CSNK2A1, SYK, CSK, and PTK2B. The potential cytotoxicity of several clinically applicable drugs that inhibit these kinases was tested in AML cell lines. The drugs lowered the viability of AML cells. The collective data suggest that AML cell-derived EVs could reflect essential leukemia biology.

Dual size-exclusion chromatography for efficient isolation of extracellular vesicles from bone marrow derived human plasma.

Isolation of pure extracellular vesicles (EVs), especially from blood, has been a major challenge in the field of EV research. The presence of lipoproteins and soluble proteins often hinders the isolation of high purity EVs upon utilization of conventional separation methods. To circumvent such problems, we designed a single-step dual size-exclusion chromatography (dSEC) column for effective isolation of highly pure EVs from bone marrow derived human plasma. With an aim to select appropriate column design parameters, we analyzed the physiochemical properties of the major substances in bone marrow derived plasma, which include EVs, lipoproteins, and soluble proteins. Based on these findings, we devised a novel dSEC column with two different types of porous beads sequentially stacked each other for efficient separation of EVs from other contaminants. The newly developed dSEC columns exhibited better performance in isolating highly pure EVs from AML plasma in comparison to conventional isolation methods.

A relationship between unrecognized anaemia and the development of type 2 diabetes mellitus in patient with cardiovascular risks.

Studies on anaemia in diabetic patients are well known. However, the data regarding association of anaemia on the development of diabetes mellitus (DM) are very limited. We aimed to evaluate the association of anaemia on the development of DM and major clinical outcomes in a series of the Korean population during 5-year clinical follow-up. The patients were retrospectively enrolled using the electronic database of Korea University Guro Hospital from January 2004 to February 2013. A total of 17 515 subjects without a history of DM were analysed. The World Health Organization definition of anaemia was used. Patients were divided into the anaemia group (n = 2907 patients) and the non-anaemia group (n = 14 608 patients). The primary endpoint was the development of DM. To adjust baseline potential confounders, a propensity score matching (PSM) analysis was performed. After PSM analysis, two matched groups (2731 pairs) were generated and their baselines characteristics were balanced. During 5-year follow-up, the anaemia group had a higher incidence of type 2 DM (10.7% vs 7.7%; hazard ratio [HR], 1.356; 95% confidence interval [CI], 1.021-1.802; P = .035), and total death (2.6% vs 1.2%; HR, 2.449; 95% CI, 1.337-4.486; P = .004) compared to the non-anaemia group. In the present study, anaemia was associated with higher rate of the development of DM and mortality during 5-year clinical follow-up. A randomized trial is needed to determine whether this results can be reproducible or not for the final conclusion.

Activation of CXCL12-CXCR4 signalling induces conversion of immortalised embryonic kidney cells into cancer stem-like cells.

Cancer stem cells (CSCs) have been implicated in the growth and progression of several types of human cancer. The technology to derive and establish CSCs in vitro could be a critical tool for understanding cancer and developing new therapeutic targets. In this study, we derived expandable CD15+ induced CSCs (iCSCs) from immortalised 293FT human epithelial cells by co-culture with human bone marrow-derived mesenchymal stem cells (BM-MSCs) as feeder cells in vitro. The iCSCs converted through an epithelial-mesenchymal transition program acquired mesenchymal traits, the expression of stem cell markers, and epigenetic changes. Moreover, the iCSCs not only efficiently formed tumorspheres in vitro but also initiated tumours in immunocompromised mice injected with only 10 of the iCSCs. Furthermore, we showed that the expression of the chemokine CXCL12 and its receptor CXCR4 by the iCSCs resulted in the activation of the Fut4 gene through CXCR4/ERK/ELK-1-signalling pathways and the maintenance of the iCSCs in the undifferentiated state through CXCR4/AKT/STAT3-signalling. These findings suggest that immortalised 293FT cells may acquire potential oncogenicity through molecular and cellular alteration processes in microenvironments using BM-MSCs, and could represent a valuable in vitro model as a cancer stem cell surrogate for studying the pathophysiological properties of CSCs.

Levels of Extracellular Vesicles in Pulmonary and Peripheral Blood Correlate with Stages of Lung Cancer Patients.

BACKGROUND: The extracellular vesicle (EV) concentration is known to be higher in cancer patients than in healthy individuals. Herein, we report that EV levels differ in the tumor-draining pulmonary vein blood and the peripheral blood of animal models and human subjects at different pathological stages of lung cancer. METHODS: Ten rabbits and 40 humans formed the study cohorts. Blood was collected from the peripheral vein of members of all groups. Pulmonary blood was collected intraoperatively from all groups except for the healthy human controls. Quantitative analysis of EV levels was performed using a nanoparticle tracking assay, a CD63 enzyme-linked immunosorbent assay, and western blotting. RESULTS: The EV levels in the peripheral blood of animals and patients with lung cancer were higher than those in the peripheral blood of healthy controls (p < 0.01 and p < 0.001, respectively). Moreover, for both animals and patients with lung cancer, the EV levels in the pulmonary blood were significantly higher than those in the preoperative peripheral blood (p < 0.01 and p < 0.0001, respectively). In patients, the pathological stages of lung cancer showed a higher correlation with the pulmonary EV levels than the peripheral EV levels. CONCLUSIONS: EV levels increased with increasing lung cancer grade, and this trend was more prominent in the pulmonary blood than in the peripheral blood.

Early-Stage Lung Cancer Diagnosis by Deep Learning-Based Spectroscopic Analysis of Circulating Exosomes.

Lung cancer has a high mortality rate, but an early diagnosis can contribute to a favorable prognosis. A liquid biopsy that captures and detects tumor-related biomarkers in body fluids has great potential for early-stage diagnosis. Exosomes, nanosized extracellular vesicles found in blood, have been proposed as promising biomarkers for liquid biopsy. Here, we demonstrate an accurate diagnosis of early-stage lung cancer, using deep learning-based surface-enhanced Raman spectroscopy (SERS) of the exosomes. Our approach was to explore the features of cell exosomes through deep learning and figure out the similarity in human plasma exosomes, without learning insufficient human data. The deep learning model was trained with SERS signals of exosomes derived from normal and lung cancer cell lines and could classify them with an accuracy of 95%. In 43 patients, including stage I and II cancer patients, the deep learning model predicted that plasma exosomes of 90.7% patients had higher similarity to lung cancer cell exosomes than the average of the healthy controls. Such similarity was proportional to the progression of cancer. Notably, the model predicted lung cancer with an area under the curve (AUC) of 0.912 for the whole cohort and stage I patients with an AUC of 0.910. These results suggest the great potential of the combination of exosome analysis and deep learning as a method for early-stage liquid biopsy of lung cancer.

Tissue inhibitor of metalloproteinase proteins inhibit teratoma growth in mice transplanted with pluripotent stem cells.

Pluripotent stem cells (PSCs) can serve as an unlimited cell source for transplantation therapies for treating various devastating diseases, such as cardiovascular diseases, diabetes, and Parkinson's disease. However, PSC transplantation has some associated risks, including teratoma formation from the remaining undifferentiated PSCs. Thus, for successful clinical application, it is essential to ablate the proliferative PSCs before or after transplantation. In this study, neural stem cell-derived conditioned medium (NSC-CM) inhibited the proliferation of PSCs and PSC-derived neural precursor (NP) cells without influencing the potential of PSC-NP cells to differentiate into neurons in vitro and prevented teratoma growth in vivo. Moreover, we found that the NSC-CM remarkably decreased the expression levels of Oct4 and cyclin D1 that Oct4 directly binds to and increased the cleaved-caspase 3-positive cell death through the DNA damage response in PSCs and PSC-NPs. Interestingly, we found that NSCs distinctly secreted the tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 proteins. These proteins suppressed not only the proliferation of PSCs in cell culture but also teratoma growth in mice transplanted with PSCs through inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 activity. Taken together, these results suggest that the TIMP proteins may improve the efficacy and safety of the PSC-based transplantation therapy.

Neural stem cells and the secreted proteins TIMPs ameliorate UVB-induced skin photodamage.

UV-induced skin damage is involved in ROS overproduction and the overexpression of matrix metalloproteinases (MMPs), which are inhibited by TIMPs (tissue inhibitor of neural stem cells (NSCs)). These proteins may be associated with skin regeneration through the activation of TIMP proteins, but there have been no reports of treatment of skin photodamage using NSCs and their secreted proteins TIMP-1 and TIMP-2. Here we investigated the photoprotective role of NSCs and their TIMP proteins for the inhibition of UVB-irradiation damage in fibroblasts in SKH-1 mice. SKH-1 hairless mice were divided into three groups (n = 4 per group): normal, treatment, and control groups. The latter two groups were dorsally exposed to UVB irradiation for 12 weeks. After UVB irradiation, treatments with NSC-CM and its secreted factors TIMP-1 and TIMP-2, markedly ameliorated the photodamage triggered by the increase in MMP expression and activity through ROS production, and the subsequent activation of the NF-κB pathway in UVB-irradiated fibroblasts and the treatment mouse group. In addition, the topical application of NSC-CM to mice in the treatment group after irradiation clearly inhibited the expression of γ-H2AX, a DNA damage marker, through the activation of the DNA repair enzyme Rad50. These results demonstrate that NSC-CM or TIMPs proteins can ameliorate skin photodamage induced by UVB-irradiation in in vitro and in vivo systems.

Effectiveness of a Fractionated Therapy Scheme in Tumor Treating Fields Therapy.

This study aimed to evaluate the biological effectiveness of cancer therapy with tumor treating fields using a fractionated treatment scheme that was originally designed for radiotherapy. Discontinuous fractional tumor treating fields of an intensity of 0.9 to 1.2 V/cm and a frequency of 150 KHz were applied to U373 cancer cells and IEC6 normal cells for 3 days, with durations of 3, 6, 12, or 24 h/d. As the treatment duration of the tumor treating fields increased from 3 to 24 h/d, the relative tumor cell (U373) number (% of control) reduced in proportion to the treatment duration. Compared to a 25% cell number reduction (75% of control) for the group of 6 h/d treatment at 1.2 V/cm, only 5% (70% of control) and 8% (67% of control) of additional reductions were observed for the group of 12 and 24 h/d treatment, respectively. This experimental result indicates that the dependence on treatment duration in tumor cell inhibition was weakened distinctly at treatment duration over 6 h/d. For normal cells (IEC6), the relative cell number corresponding to the treatment time of the tumor treating fields at 1.2 V/cm of electric field strength was not decreased much for the treatment times of 3, 6, and 12 h/d, revealing 93.3%, 90.0%, and 89.3% relative cell numbers, respectively, but it suddenly decreased to ∼73% for the 24 h/d treatment. Our results showed that the effects of tumor treating fields on tumor cells were higher than on normal cells for treatment duration of 3 to 12 h/d, but the difference became minimal for treatment duration of 24 h/d. The fractionated scheme, using tumor treating fields, reduced the treatment time while maintaining efficacy, suggesting that this method may be clinically applicable for cancer treatment.

Correlation between Cancerous Exosomes and Protein Markers Based on Surface-Enhanced Raman Spectroscopy (SERS) and Principal Component Analysis (PCA).

Exosomes, which are nanovesicles secreted by cells, are promising biomarkers for cancer diagnosis and prognosis, based on their specific surface protein compositions. Here, we demonstrate the correlation of nonsmall cell lung cancer (NSCLC) cell-derived exosomes and potential protein markers by unique Raman scattering profiles and principal component analysis (PCA) for cancer diagnosis. On the basis of surface enhanced Raman scattering (SERS) signals of exosomes from normal and NSCLC cells, we extracted Raman patterns of cancerous exosomes by PCA and clarified specific patterns as unique peaks through quantitative analysis with ratiometric mixtures of cancerous and normal exosomes. The unique peaks correlated well with cancerous exosome ratio ( R2 > 90%) as the unique Raman band of NSCLC exosome. To examine the origin of the unique peaks, we compared these unique peaks with characteristic Raman bands of several exosomal protein markers (CD9, CD81, EpCAM, and EGFR). EGFR had 1.97-fold similarity in Raman profiles than other markers, and it showed dominant expression against the cancerous exosomes in an immunoblotting result. We expect that these results will contribute to studies on exosomal surface protein markers for diagnosis of cancers.

The Potential of Exosomes Derived from Chronic Myelogenous Leukaemia Cells as a Biomarker.

BACKGROUND/AIM: Exosomes, derived from chronic myelogenous leukaemia (CML) cells, can be used as biomarkers and new targets for the detection of the BCR-ABL transcript. This study aimed to identify these possibilities. MATERIALS AND METHODS: Human CML cell line-derived exosomes and CML-patients-derived exosomes were isolated with a size-exclusion chromatography column and ExoQuick™ exosome precipitation solution, respectively. Isolated exosomes were analysed by nested PCR to detect the BCR-ABL transcript. RESULTS: Exosomes derived from the two human CML cell lines yielded a 250-bp band. RNA sequence analysis revealed 99% sequence homology with the partial mRNA for the human BCR-ABL chimeric protein. This ~250-bp band was also observed in the exosomes derived from patients with CML. However, only patients at the blast and accelerated phases showed the exosomal BCR-ABL transcript. CONCLUSION: CML-derived exosomes could act as novel targets for the detection of the BCR-ABL transcript.

Precise nanoinjection delivery of plasmid DNA into a single fibroblast for direct conversion of astrocyte.

Direct conversion is a powerful approach to safely generate mature neural lineages with potential for treatment of neurological disorders. Astrocytes play a crucial role in neuronal homeostasis and their dysfunctions contribute to several neurodegenerative diseases. Using a single-cell approach for precision, we describe here a robust method using optimized DNA amounts for the direct conversion of mouse fibroblasts to astrocytes. Controlled amount of the reprogramming factors Oct4, Sox2, Klf4 and cMyc was directly delivered into a single fibroblast cell. Consequently, 2500 DNA molecules, no more or less, were found to be the optimal amount that dramatically increased the expression levels of the astrocyte-specific markers GFAP and S100b and the demethylation gene TET1, the expression of which was sustained to maintain astrocyte functionality. The converted astrocytes showed glutamate uptake ability and electrophysiological activity. Furthermore, we demonstrated a potential mechanism whereby fibroblast was directly converted into astrocyte at a single-cell level; this was achieved by activating BMP2 pathway through direct binding of Sox2 protein to BMP2 gene. This study suggests that nanotechnology for directly injecting plasmid DNAs into cell nuclei may help understand such a conversion at single-cell level.

Stem cell transplantation for Huntington's diseases.

Therapeutic approaches based on stem cells have received considerable attention as potential treatments for Huntington's disease (HD), which is a fatal, inherited neurodegenerative disorder, caused by progressive loss of GABAergic medium spiny neurons (MSNs) in the striatum of the forebrain. Transplantation of stem cells or their derivatives in animal models of HD, efficiently improved functions by replacing the damaged or lost neurons. In particular, neural stem cells (NSCs) for HD treatments have been developed from various sources, such as the brain itself, the pluripotent stem cells (PSCs), and the somatic cells of the HD patients. However, the brain-derived NSCs are difficult to obtain, and the PSCs have to be differentiated into a population of the desired neuronal cells that may cause a risk of tumor formation after transplantation. In contrast, induced NSCs, derived from somatic cells as a new stem cell source for transplantation, are less likely to form tumors. Given that the stem cell transplantation strategy for treatment of HD, as a genetic disease, is to replace the dysfunctional or lost neurons, the correction of mutant genes containing the expanded CAG repeats is essential. In this review, we will describe the methods for obtaining the optimal NSCs for transplantation-based HD treatment and the differentiation conditions for the functional GABAergic MSNs as therapeutic cells. Also, we will discuss the valuable gene correction of the disease stem cells by the CRISPR/Cas9 system for HD treatment.

Neural Stem Cells and Its Derivatives as a New Material for Melanin Inhibition.

The pigment molecule, melanin, is produced from melanosomes of melanocytes through melanogenesis, which is a complex process involving a combination of chemical and enzymatically catalyzed reactions. The synthesis of melanin is primarily influenced by tyrosinase (TYR), which has attracted interest as a target molecule for the regulation of pigmentation or depigmentation in skin. Thus, direct inhibitors of TYR activity have been sought from various natural and synthetic materials. However, due to issues with these inhibitors, such as weak or permanent ability for depigmentation, allergy, irritant dermatitis and rapid oxidation, in vitro and in vivo, the development of new materials that inhibit melanin production is essential. A conditioned medium (CM) derived from stem cells contains many cell-secreted factors, such as cytokines, chemokines, growth factors and extracellular vesicles including exosomes. In addition, the secreted factors could negatively regulate melanin production through stimulation of a microenvironment of skin tissue in a paracrine manner, which allows the neural stem cell CM to be explored as a new material for skin depigmentation. In this review, we will summarize the current knowledge regulating depigmentation, and discuss the potential of neural stem cells and their derivatives, as a new material for skin depigmentation.

Induced neural stem cells as a means of treatment in Huntington's disease.

INTRODUCTION: Huntington's disease (HD) is an inherited neurodegenerative disease characterized by chorea, dementia, and depression caused by progressive nerve cell degeneration, which is triggered by expanded CAG repeats in the huntingtin (Htt) gene. Currently, there is no cure for this disease, nor is there an effective medicine available to delay or improve the physical, mental, and behavioral severities caused by it. Areas covered: In this review, the authors describe the use of induced neural stem cells (iNSCs) by direct conversion technology, which offers great advantages as a therapeutic cell type to treat HD. Expert opinion: Cell conversion of somatic cells into a desired stem cell type is one of the most promising treatments for HD because it could be facilitated for the generation of patient-specific neural stem cells. The induced pluripotent stem cells (iPSCs) have a powerful potential for differentiation into neurons, but they may cause teratoma formation due to an undifferentiated pluripotent stem cell after transplantation Therefore, direct conversion of somatic cells into iNSCs is a promising alternative technology in regenerative medicine and the iNSCs may be provided as a therapeutic cell source for Huntington's disease.