Disseminated non-tuberculous mycobacterial infection caused by Mycobacterium obuense in an immunocompromised patient: a case report.

BACKGROUND: Mycobacterium obuense (M. obuense) is a rapidly growing mycobacterium (RGM) which has been considered nonpathogenic. Here, we report a case of disseminated non-tuberculous mycobacterial (NTM) infection caused by M. obuense in an immunocompromised patient. CASE PRESENTATION: A 16-year-old boy was referred to our hospital due to acute myeloid leukemia. During the treatment of leukemia, the patient exhibited continuous fever, and diffuse miliary nodules with random distribution were found on chest computed tomography. Repeated examinations of bacterial culture tests revealed sputum and urine samples to be smear-positive for acid-fast bacillus, and blood culture from a peripherally inserted central catheter line showed the growth of NTM. The NTM species was identified as M. obuense by mass spectrometry and confirmed by genome sequencing. Combination therapy with amikacin, rifampicin, azithromycin, and moxifloxacin significantly improved the patient's symptoms and radiological findings. CONCLUSION: We report a case of disseminated NTM infection caused by M. obuense for which combination anti-microbial therapy was effective. An immunocompromised host indwelling catheter is at risk of RGM bloodstream infections. Although relatively rare, M. obuense may be considered as a potential pathogen causing infectious diseases, especially in high-risk patients.

Micromorphological observation of HLE cells under knockdown of Fascin using LV-SEM.

Liver cancer is one of the most prevalent cancers in Japan with hepatocellular carcinoma (HCC) as the major histological subtype. Successful novel treatments for HCC have been reported; however, recurrences or metastasis may occur, which results in poor prognoses and high mortality of HCC patients. Fascin, an actin-bundling protein, regulates cell adhesion, migration, and invasion. Its overexpression positively correlates with poor prognosis of malignant tumors, and Fascin is considered as one of the tumor biomarkers and therapeutic target proteins. In this study, we attempted to reveal the relationship between Fascin and HCC using HLE, one of the human HCC cell lines. We performed the study with classical immunocytochemistry and recently developed techniques, such as wound-healing assay, spheroid cultivation, and low-vacuum scanning electron microscopy (LV-SEM). Non-Fascin-knockdown (FKD) cell spheroid had a regular spherical appearance with tight cell-cell connections, while FKD cell spheroid had an irregular shape with loose cell-cell connections. Cells of non-FKD spheroid presented fibrous protrusions on the cell surface, contrarily, cells of FKD spheroids showed bulbous-shaped protrusions. Morphological observation of FKD and non-FKD HLE spheroids were performed using LV-SEM. Our study may help to reveal the roles of Fascin in the process of HCC formation and its malignancy.

Fascin expression persists with fibronectin in embryonic rat hepatoblasts.

Both fascin and fibronectin are known to play important roles in cell adhesion and migration. They are noted as tumor markers or inhibiting target for tumor treatment. In this study, embryonic rat livers were obtained to examine the expression of fascin and fibronectin during liver development. Then, the effect of fibronectin on fascin expression was investigated. At embryonic day (ED) 10.5, when the foregut endoderm began to form the liver bud and spread into the septum transversum, fibrous extracellular matrix was observed between the space where the liver bud and the septum transversum merged. At ED11.5, fibronectin was observed surrounding the cluster of fascin-positive hepatoblasts. At ED13.5, hematopoietic cells emerged and both fibronectin and fascin expression started to decline. Fascin and fibronectin appeared temporarily and disappeared by ED 14.5. Their expression was chronologically synchronized. Subsequently, the effect of fibronectin on fascin was examined by cultivation of hepatoblasts that were isolated from the ED13.5 rat liver. As a result, with fibronectin, fascin was positive in most hepatoblasts, although, without fibronectin, fascin expression was remarkably declined. Presently, there are few studies about the relationship between fascin and fibronectin. Our findings suggest that fibronectin could regulate fascin expression in rat hepatoblasts.

The impact of bronchial artery embolisation on the quality of life of patients with haemoptysis: a prospective observational study.

OBJECTIVES: Patients with haemoptysis often experience daily physical and mental impairment. Bronchial artery embolisation is among the first-line treatment options used worldwide; however, no evidence exists regarding the health-related quality of life (HRQoL) after bronchial artery embolisation. Therefore, this study aimed to evaluate the effects of bronchial artery embolisation on the HRQoL of patients with haemoptysis. METHODS: We prospectively enrolled 61 consecutive patients who visited our hospital from July 2017 to August 2018 and received bronchial artery embolisation for haemoptysis. The primary outcome was the HRQoL evaluated using the Short Form Health Survey, which contains physical and mental components, before and after bronchial artery embolisation. The secondary outcomes were procedural success, complications, and recurrence-free survival rate at 6 months. RESULTS: The mean age of the patients was 69 years (range, 31-87 years). The procedural success rate was 98%. No major complications occurred. The recurrence-free survival rate estimated using the Kaplan-Meier analysis at 6 months after bronchial artery embolisation was 91.8% (95% confidence interval, 91.1-92.5%). Compared with the pre-treatment scores, the physical and mental scores were significantly improved at 6 months after bronchial artery embolisation (p < 0.05). CONCLUSION: Bronchial artery embolisation improved the HRQoL of patients with haemoptysis. KEY POINTS: • Bronchial artery embolisation improved the HRQoL of patients with haemoptysis. • Vessel dilation on computed tomography and systemic artery-pulmonary artery direct shunting on angiography were the most common abnormalities. • The recurrence-free survival rate estimated using the Kaplan-Meier analysis at 6 months after bronchial artery embolisation was 91.8%.

Elizabethkingia anophelis, an emerging pathogen, inhibits RAW 264.7 macrophage function.

Elizabethkingia anophelis is a pathogen that can cause a life-threatening infection in immunocompromised patients. The first case of E. anophelis infection was reported in 2013; subsequently, an increase in its incidence has been reported globally. Additionally, a mortality rate of more than 30% was observed in the US outbreak of 2015. To date, the pathogenic mechanisms underlying E. anophelis infection, such as toxin production, remain unclear. Since tissue macrophages act as the first line of defense against pathogens, in the present study the interactions between E. anophelis and a macrophage-like cell line RAW 264.7 were examined. Although E. anophelis showed no cytotoxicity toward RAW 264.7 macrophages, the infection inhibited LPS-induced morphological changes and activation of differentiation markers for the polarization of RAW 264.7 macrophages toward an M1-like phenotype. However, when the cell contact was restricted using Transwell inserts or bacterial culture supernatants were used instead of live bacteria, no such inhibition was observed. Moreover, it was shown that E. anophelis evaded phagocytosis. Overall, the results suggest that E. anophelis infection inhibits the differentiation of RAW 264.7 macrophages to a pro-inflammatory phenotype in a contact-dependent manner.

Recurrence of Solitary Fibrous Tumor/Hemangiopericytoma Could Be Predicted by Ki-67 Regardless of Its Origin.

Since the discovery of the NAB2-STAT6 gene fusion in 2013, solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) have been considered the same disease. STAT6 nuclear stain is approved as a highly sensitive and specific marker to diagnose SFT/HPC from other tumors with similar histology. As the next step, detection of fusion variants that may predict clinical malignancy of SFT/HPC has been attempted. However, no fusion variants with a clear relation to malignancy have been identified. In this study, the clinical and histological backgrounds of 23 Japanese patients diagnosed with SFT/HPC from 2000 to 2019 at Kochi University Hospital were examined to identify factors potentially related to recurrence. A significant relationship to recurrence was detected for mitosis ≥ 1/10 HPF (400×), necrosis, and Ki-67>5%. These findings indicate that a deliberate investigation of histological features such as mitosis and necrosis is crucial for the clinical observation of SFT/ HPC patients. In addition, Ki-67 was revealed to be a useful parameter to predict recurrence in SFT/HPC patients.

Analysis of a plasmid encoding botulinum neurotoxin type G gene in Clostridium argentinense.

Clostridium argentinense produces botulinum neurotoxin type G (BoNT/G). We sequenced and analyzed the plasmid harboring the bont/G gene, designated pCAG, in C. argentinense strain 2740. The pCAG consisted of 140,070 bp containing the bont/G gene cluster. Although this gene cluster showed high similarities in its DNA sequence and ORF arrangement to those of other bont gene clusters, the other regions of the plasmid did not. A phylogenetic study suggested that pCAG had a unique evolutionary history compared with other clostridial bont-harboring plasmids. This suggests that pCAG is possibly a novel type of plasmid expressing the bont/G gene in C. argentinense.

Expression of Collagenase is Regulated by the VarS/VarA Two-Component Regulatory System in Vibrio alginolyticus.

Vibrio alginolyticus is an opportunistic pathogen in both humans and marine animals. Collagenase encoded by colA is considered to be one of the virulence factors. Expression of colA is regulated by multiple environmental factors, e.g., temperature, growth phase, and substrate. To elucidate the mechanism of regulation of colA expression, transposon mutagenesis was performed. VarS, a sensor histidine kinase of the two-component regulatory system, was demonstrated to regulate the expression of colA. VarA, a cognate response regulator of VarS, was also identified and shown to be involved in the regulation of colA expression. In vitro phosphorylation assays showed that phosphorylated VarS acted as a phosphoryl group donor to VarA. A site-directed mutagenesis study showed that the His300, Asp718 and His874 residues in VarS were essential for the phosphorylation of VarS, and the Asp54 residue in VarA was likely to receive the phosphoryl group from VarS. The results demonstrate that the VarS/VarA two-component regulatory system regulates the expression of collagenase in V. alginolyticus.

Vibrio alginolyticus VepA Induces Lysosomal Membrane Permeability and Cathepsin-Independent Cell Death.

The bacterium Vibrio alginolyticus, an opportunistic pathogen in humans, has a type III secretion system (T3SS) that is responsible for its cytotoxicity toward eukaryotic cells. The effector of T3SS that is responsible for the cytotoxicity had not been identified. Here we demonstrate that VepA, a homolog of the T3SS effector in V. parahaemolyticus, is required for cytotoxicity in V. alginolyticus. VepA induces lysosomal membrane permeabilization, and it allows the leakage of only small molecules into the cytosol. Our findings revealed that VepA induces cathepsin-independent cell death in mammalian cells. The ferrous ion, one of the small molecules in the lysosome contents, appears to be involved in the cell death caused by V. alginolyticus VepA.

Density Gradient Centrifugation for the Isolation of Cells of Multiple Lineages.

We recently developed a simple strategy for the enrichment of mesenchymal stem cells (MSCs) with the capacity for osteoblast, chondrocyte, and adipocyte differentiation. On transplantation, the progenitor-enriched fraction can regenerate bone with multiple lineages of donor origin. Although comprising multiple precursor cell types, the population is enriched >100-fold in osteoprogenitors, hence the name "highly purified osteoprogenitors" (HipOPs). To establish a new modified method of purifying pure MSCs, it is useful to know the expression patterns of surface markers on heterogeneous MSCs and committed cells such as osteoblasts, adipocytes, and chondrocytes. However, calcium deposition by osteoblasts is a critical obstacle in visualizing the expression patterns of surface markers. We now report a new method of separating differentiated osteoblastic HipOPs (OB-HipOPs) from calcium deposits using the Percoll density gradient centrifugation technique. After centrifuge separation, calcium deposits were observed at the bottom of the centrifuge tube, and living OB-HipOPs were harvested from the 10-70% fractions. However, there were no living cells in the 70-80% fraction. We concluded that living OB-HipOPs are separated by one 10-70% Percoll gradient. Furthermore, we analyzed the expression patterns of putative MSC markers on differentiated HipOPs. FACS analysis revealed that Sca-1, CD44, CD73, CD105, and CD106 were decreased in OB-HipOPs. In adipogenic- and chondrogenic-HipOPs, Sca-1, CD73, CD105, and CD106 were decreased. This new technique is a helpful tool to identify MSC surface markers and to clarify in more detail the differentiation stages of osteoblasts.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2010: General view of the pathogens' antibacterial susceptibility.

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from patients in Japan, was conducted by Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases and Japanese Society for Clinical Microbiology in 2010. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period from January and April 2010 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical and Laboratory Standard Institutes using maximum 45 antibacterial agents. Susceptibility testing was evaluable with 954 strains (206 Staphylococcus aureus, 189 Streptococcus pneumoniae, 4 Streptococcus pyogenes, 182 Haemophilus influenzae, 74 Moraxella catarrhalis, 139 Klebsiella pneumoniae and 160 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was as high as 50.5%, and those of penicillin-intermediate and -resistant S. pneumoniae were 1.1% and 0.0%, respectively. Among H. influenzae, 17.6% of them were found to be ß-lactamase-non-producing ampicillin (ABPC)-intermediately resistant, 33.5% to be ß-lactamase-non-producing ABPC-resistant and 11.0% to be ß-lactamase-producing ABPC-resistant strains. Extended spectrum ß-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo ß-lactamase were 2.9% and 0.6%, respectively. Continuous national surveillance of antimicrobial susceptibility of respiratory pathogens is crucial in order to monitor changing patterns of susceptibility and to be able to update treatment recommendations on a regular basis.

LIF/STAT3/SOCS3 signaling pathway in murine bone marrow stromal cells suppresses osteoblast differentiation.

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine that belongs to the interleukin-6 family and is expressed by multiple tissue types. This study analyzed the effect of LIF on osteoblast differentiation using primary murine bone marrow stromal cells (BMSCs). Colony-forming unit-osteoblast formation by BMSCs was significantly suppressed by LIF treatment. To clarify the mechanism underlying the LIF suppressive effect on osteoblast differentiation, we analyzed the downstream signaling pathway of LIF. LIF/signal transducer and activator of transcription 3 (STAT3) signaling induces the expression of suppressor of cytokine signaling 3 (SOCS3). SOCS3 knockdown experiments have previously demonstrated that short-hairpin SOCS3-BMSCs reversed the LIF suppressive effect. Our results demonstrated that LIF suppresses osteoblast differentiation through the LIF/STAT3/SOCS3 signaling pathway.

Effects of methylglyoxal on human cardiac fibroblast: roles of transient receptor potential ankyrin 1 (TRPA1) channels.

Cardiac fibroblasts contribute to the pathogenesis of cardiac remodeling. Methylglyoxal (MG) is an endogenous carbonyl compound produced under hyperglycemic conditions, which may play a role in the development of pathophysiological conditions including diabetic cardiomyopathy. However, the mechanism by which this occurs and the molecular targets of MG are unclear. We investigated the effects of MG on Ca(2+) signals, its underlying mechanism, and cell cycle progression/cell differentiation in human cardiac fibroblasts. The conventional and quantitative real-time RT-PCR, Western blot, immunocytochemical analysis, and intracellular Ca(2+) concentration [Ca(2+)]i measurement were applied. Cell cycle progression was assessed using the fluorescence activated cell sorting. MG induced Ca(2+) entry concentration dependently. Ruthenium red (RR), a general cation channel blocker, and HC030031, a selective transient receptor potential ankyrin 1 (TRPA1) antagonist, inhibited MG-induced Ca(2+) entry. Treatment with aminoguanidine, a MG scavenger, also inhibited it. Allyl isothiocyanate, a selective TRPA1 agonist, increased Ca(2+) entry. The use of small interfering RNA to knock down TRPA1 reduced the MG-induced Ca(2+) entry as well as TRPA1 mRNA expression. The quantitative real-time RT-PCR analysis showed the prominent existence of TRPA1 mRNA. Expression of TRPA1 protein was confirmed by Western blotting and immunocytochemical analyses. MG promoted cell cycle progression from G0/G1 to S/G2/M, which was suppressed by HC030031 or RR. MG also enhanced α-smooth muscle actin expression. The present results suggest that methylglyoxal activates TRPA1 and promotes cell cycle progression and differentiation in human cardiac fibroblasts. MG might participate the development of pathophysiological conditions including diabetic cardiomyopathy via activation of TRPA1.

Irregular Tremulous Movements and Infrequent Seizures: A Clinical-Electrophysiological Diagnosis of Benign Adult Familial Myoclonus Epilepsy.

We report a case involving a 31-year-old male without any known precipitating injuries presenting with involuntary finger movements and rare seizures. There was a noted family history of tremulous movements. Yet the characteristics of his finger movements were irregular and not typical of essential tremor (ET). Electrophysiological examinations, including video EEG, showed no epileptic discharges, and brain MRI results were normal. However, somatosensory evoked potentials (SEP) revealed the presence of giant SEP, and a positive cortical (C)-reflex was observed, leading to a clinical diagnosis of benign adult familial myoclonus epilepsy (BAFME). Management with valproic acid and perampanel resulted in a significant reduction of symptoms. This case highlights the necessity of considering BAFME in the differential diagnosis for atypical tremorous finger movements, especially with a relevant family history, and the critical role of electrophysiological findings indicative of cortical hyperexcitability.

Intravenous Thrombolysis for Pediatric Ischemic Stroke Secondary to Cancer Therapy-related Cardiac Dysfunction: A Case Report.

An 11-year-old boy developed cardioembolic stroke (CES) and cancer therapy-related cardiac dysfunction (CTRCD). He originally developed Ewing sarcoma and was treated with high-dose chemotherapy including doxorubicin. On admission, he had severe aphasia, and magnetic resonance imaging showed occlusion of the left middle cerebral artery M3 segment. Transthoracic echocardiography revealed severe left ventricular dysfunction and a mobile thrombus at the left ventricular apex. Intravenous thrombolysis was administered, and effective recanalization was achieved. The patient did not exhibit any neurological deficits during discharge. Reperfusion therapy for pediatric patients has not yet been established; however, it may be effective for CES secondary to CTRCD.

ROR2 expression predicts human induced pluripotent stem cell differentiation into neural stem/progenitor cells and GABAergic neurons.

Despite the development of various in vitro differentiation protocols for the efficient derivation of specific cell types, human induced pluripotent stem cell (hiPSC) lines have varing ability to differentiate into specific lineages. Therefore, surrogate markers for accurately predicting the differentiation propensity of hiPSC lines may facilitate cell-based therapeutic product development and manufacture. We attempted to identify marker genes that could predict the differentiation propensity of hiPSCs into neural stem/progenitor cells (NS/PCs). Using Spearman's rank correlation coefficients, we investigated genes in the undifferentiated state, the expression levels of which were significantly correlated with the neuronal differentiation propensity of several hiPSC lines. Among genes significantly correlated with NS/PC differentiation (P < 0.01), we identified ROR2 as a novel predictive marker. ROR2 expression in hiPSCs was negatively correlated with NS/PC differentiation tendency, regardless of the differentiation method, whereas its knockdown enhanced differentiation. ROR2 regulates NS/PC differentiation, suggesting that ROR2 is functionally essential for NS/PC differentiation. Selecting cell lines with relatively low ROR2 expression facilitated identification of hiPSCs that can differentiate into NS/PCs. Cells with ROR2 knockdown showed increased efficiency of differentiation into forebrain GABAergic neurons compared to controls. These findings suggest that ROR2 is a surrogate marker for selecting hiPSC lines appropriate for NS/PC and GABAergic neuronal differentiations.

Phospholipase C produced by Clostridium botulinum types C and D: comparison of gene, enzymatic, and biological activities with those of Clostridium perfringens alpha-toxin.

Clostridium botulinum type C and D strains recently have been found to produce PLC on egg yolk agar plates. To characterize the gene, enzymatic and biological activities of C. botulinum PLCs (Cb-PLCs), the cb-plc genes from 8 strains were sequenced, and 1 representative gene was cloned and expressed as a recombinant protein. The enzymatic and hemolytic activities of the recombinant Cb-PLC were measured and compared with those of the Clostridium perfringens alpha-toxin. Each of the eight cb-plc genes encoded a 399 amino acid residue protein preceded by a 27 residue signal peptide. The protein consists of 2 domains, the N- and C-domains, and the overall amino acid sequence identity between Cb-PLC and alpha-toxin was greater than 50%, suggesting that Cb-PLC is homologous to the alpha-toxin. The key residues in the N-domain were conserved, whereas those in the C-domain which are important in membrane interaction were different than in the alpha-toxin. As expected, Cb-PLC could hydrolyze egg yolk phospholipid, p-nitrophenylphosphorylcholine, and sphingomyelin, and also exhibited hemolytic activity;however, its activities were about 4- to over 200-fold lower than those of alpha-toxin. Although Cb-PLC showed weak enzymatic and biological activities, it is speculated that Cb-PLC might play a role in the pathogenicity of botulism or for bacterial survival.

Mechanism and clinical use of botulinum neurotoxin in head and facial region.

PURPOSE: Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region. STUDY SELECTION: MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles. RESULTS: The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia. CONCLUSIONS: BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Downregulation of fascin induces collective cell migration in triple­negative breast cancer.

Breast cancer (BC) is one of the most common types of cancer affecting female patients. Triple­negative BC (TNBC) is an aggressive subtype. Fascin, an actin­bundling protein, serves a significant role in cancer metastasis. Fascin overexpression is associated with poor prognosis of BC. To confirm the relationship between fascin expression and BC malignancy, the present study reviewed clinical data from 100 Japanese patients with BC and performed fresh immunohistochemical fascin examination of tissue samples. Statistical analyses showed metastasis or recurrence in 11 of 100 patients and a significant association between high fascin expression and poor prognosis. The TNBC subtype was also associated with high fascin expression. However, a few cases developed poor prognosis regardless of negative or slightly positive fascin expression. The present study established fascin knockdown (FKD) MDA­MB­231, a TNBC cell line, and investigated morphological effects of fascin on TNBC cells. FKD cells exhibited cell­cell connections and bulbous nodules of various sizes on the cell surface. Conversely, non­FKD MDA­MB­231 cells exhibited loose cell­cell connections with numerous filopodia on the cell surface. Filopodia, actin­rich plasma membrane protrusions, are composed of fascin and control cell­cell interaction, migration and wound healing. Cancer metastasis is conventionally classified into two mechanisms: single and collective cell migration. Fascin increases cancer metastasis by single cell migration via filopodia on the cell surface. However, the present study suggested that following FKD, TNBC cells lost filopodia and exhibited collective cell migration.

Single-Cell RNA-Seq Reveals LRRC75A-Expressing Cell Population Involved in VEGF Secretion of Multipotent Mesenchymal Stromal/Stem Cells Under Ischemia.

Human multipotent mesenchymal stromal/stem cells (MSCs) have been utilized in cell therapy for various diseases and their clinical applications are expected to increase in the future. However, the variation in MSC-based product quality due to the MSC heterogeneity has resulted in significant constraints in the clinical utility of MSCs. Therefore, we hypothesized that it might be important to identify and ensure/enrich suitable cell subpopulations for therapies using MSC-based products. In this study, we aimed to identify functional cell subpopulations to predict the efficacy of angiogenic therapy using bone marrow-derived MSCs (BM-MSCs). To assess its angiogenic potency, we observed various levels of vascular endothelial growth factor (VEGF) secretion among 11 donor-derived BM-MSC lines under in vitro ischemic culture conditions. Next, by clarifying the heterogeneity of BM-MSCs using single-cell RNA-sequencing analysis, we identified a functional cell subpopulation that contributed to the overall VEGF production in BM-MSC lines under ischemic conditions. We also found that leucine-rich repeat-containing 75A (LRRC75A) was more highly expressed in this cell subpopulation than in the others. Importantly, knockdown of LRRC75A using small interfering RNA resulted in significant inhibition of VEGF secretion in ischemic BM-MSCs, indicating that LRRC75A regulates VEGF secretion under ischemic conditions. Therefore, LRRC75A may be a useful biomarker to identify cell subpopulations that contribute to the angiogenic effects of BM-MSCs. Our work provides evidence that a strategy based on single-cell transcriptome profiles is effective for identifying functional cell subpopulations in heterogeneous MSC-based products.