Automated algorithm aided capacity and confidence boost in surgical decision-making training for inferior clivus.

Objective: To assess the impact of automated algorithms on the trainees' decision-making capacity and confidence for individualized surgical planning. Methods: At Chinese PLA General Hospital, trainees were enrolled to undergo decision-making capacity and confidence training through three alternative visual tasks of the inferior clivus model formed from an automated algorithm and given consecutively in three exemplars. The rationale of automated decision-making was used to instruct each trainee. Results: Following automated decision-making calculation in 50 skull base models, we screened out three optimal plans, infra-tubercle approach (ITA), trans-tubercle approach (TTA), and supra-tubercle approach (STA) for 41 (82.00%), 8 (16.00%), and 1 (2.00%) subject, respectively. From September 1, 2023, through November 17, 2023, 62 trainees (median age [range]: 27 [26-28]; 28 [45.16%] female; 25 [40.32%] neurosurgeons) made a decision among the three plans for the three typical models (ITA, TTA, and STA exemplars). The confidence ratings had fine test-retest reliability (Spearman's rho: 0.979; 95% CI: 0.970 to 0.988) and criterion validity with time spent (Spearman's rho: -0.954; 95%CI: -0.963 to -0.945). Following instruction of automated decision-making, time spent (initial test: 24.02 vs. 7.13 in ITA; 30.24 vs. 7.06 in TTA; 34.21 vs. 12.82 in STA) and total hits (initial test: 30 vs. 16 in ITA; 37 vs. 17 in TTA; 42 vs. 28 in STA) reduced significantly; confidence ratings (initial test: 2 vs. 4 in ITA; 2 vs. 4 in TTA; 1 vs. 3 in STA) increased correspondingly. Statistically significant differences (P < 0.05) were observed for the above comparisons. Conclusions: The education tool generated by automated decision-making considers surgical freedom and injury risk for the individualized risk-benefit assessment, which may provide explicit information to increase trainees' decision-making capacity and confidence.

Facile Preparation of Four-Layer MoS2 Nanosheets and Their Application to Organic Light-Emitting Diode.

High-quality four-layer molybdenum disulfide (MoS2) nanosheets with lateral dimension of about 11 µm were prepared by ultrasonic treatment of MoS2 powder with assistance of 1-methyl-2-pyrrolidone (NMP) solvent. The optimal preparation conditions for the preparation of MoS2 nanosheets were investigated from the aspects of ultrasonic processing time, ultrasonic power and amount ratio of MoS2 powder and NMP solvent. At the same time, the MoS2 nanosheets were employed as anode buffer layer in organic light-emitting diode (OLED) with copper nanowire (CuNW) film being anode. MoS2 nanosheets can reduce roughness of CuNW film, protect CuNW film from oxidation and improve work function of CuNW film. Experiments show that MoS2 nanosheets can significantly improve the current density and brightness of the OLED with CuNW film being anode. The maximum brightness of the OLED with MoS2 anode buffer layer is 2.15 times that of the OLED without MoS2 anode buffer layer. The current density of the OLED with MoS2 anode buffer layer is also obviously increased compared with the OLED without MoS2 anode buffer layer.

Neobacillus paridis sp. nov., an endophyte of Paris polyphylla Smith var. yunnanensis.

A novel endophytic strain, designated YIM B02564T, was isolated from the root of Paris polyphylla Smith var. yunnanensis obtained from Yunnan Province, southwest China. By using a polyphasic approach, cells of the strain were characterized as facultative anaerobic, Gram-positive and rod-shaped. The growth conditions of the strain were found to occur at 20-55 °C (optimum, 30 °C), pH 6.0-9.0 (optimum, pH 7.0). Strain YIM B02564T can tolerate 2% NaCl concentration. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YIM B02564T belonged to the genus Neobacillus and the 16S rRNA gene sequence similarity values of strain YIM B02564T to the type strains of members of this genus ranged from 95.6 to 97.8%. The DNA G+C content of strain YIM B02564T calculated from the whole genome sequence was 41.6 mol%. Values of the ANI and the dDDH between strain YIM B02564T and its closely related Neobacillus species were below 77.9% and 21.5%. Strain YIM B02564T contained MK-7 as the major menaquinone, iso-C15:0 and anteiso-C15:0 as the major fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminophospholipid and four unidentified lipids. It contained meso-diaminopimelic acid in the cell-wall peptidoglycan. On the basis of polyphasic analysis, strain YIM B02564T could be differentiated genotypically and phenotypically from recognized species of the genus Neobacillus. The isolate therefore represents a novel species, for which the name Neobacillus paridis is proposed. The type strain is YIM B02564T (= JCM 34668T = CGMCC 1.18655T).

Janibacter endophyticus sp. nov., an Endophytic Actinobacterium Isolated from the Root of Paris polyphylla Smith var. Yunnanensis.

A novel endophytic actinobacterium, designated as strain YIM B02568T, was isolated from the root of Paris polyphylla Smith var. Yunnanensis obtained from Yunnan Province, southwest China. Strain YIM B02568T was characterized using a polyphasic approach. Phylogenetic analysis indicated that this isolate belonged to the genus Janibacter. The 16S rRNA gene sequence similarity values of strain YIM B02568T to the type strains of members of this genus ranged from 95.8 to 98.6%. However, overall genome relatedness indices were significantly lower than the widely accepted species-defined threshold. The cell wall of strain YIM B02568T contained meso-diaminopimelic acid. The major menaquinone was MK-8(H4). The main polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. The major cellular fatty acids were comprised of iso-C16:0 and C18:1 ω9c. The DNA G + C content was 71.6 mol%. Based on the data from the polyphasic studies, we propose that strain YIM B02568T represents a novel species within the genus Janibacter, Janibacter endophyticus sp. nov. The type strain is YIM B02568T (= JCM 34639T = CGMCC 1.18658T).

Multitime point pepsin testing can double the rate of the diagnosis of laryngopharyngeal reflux.

OBJECTIVE: To study the value of multitime point salivary pepsin testing (MTPSPT) for the diagnosis of laryngopharyngeal reflux (LPR). STUDY DESIGN: Prospective noncontrolled. METHODS: For patients who met the enrollment criteria, the reflux symptom index (RSI) and reflux finding score (RFS) were calculated and salivary pepsin testing was performed. The pepsin test was performed every hour from 7:00 a.m. to 6:00 p.m. by collecting fresh saliva samples. A single positive test result was needed for the diagnosis of LPR. The consistency in the diagnosis of LPR between the two methods was compared with the weighted Cohen's kappa statistic. RESULTS: A total of 204 patients were included. The kappa value between the two methods was 0.566 (p = .00). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MTPSPT were 76.43%, 85.94%, 92.24%, and 62.5%, respectively. We also compared a single pepsin measure at 7 a.m. with the screening results based on the RSI and RFS, and found a much lower kappa agreement value (0.223, p = .00). The sensitivity, specificity, PPV, NPV, and false-negative rate of pepsin testing at 7 a.m. (fasting) were 37.86%, 92.18%, 91.38%, 40.41%, and 58.57%, respectively. CONCLUSION: The use of the result of a single salivary pepsin test in the morning yields a relatively higher rate of missed diagnosis of LPR, and multitime point testing through a day increased the accuracy and sensitivity of detection of LPR twofold compared to a single morning fasting sample. LEVEL OF EVIDENCE: 3.

Chryseobacterium paridis sp. nov., an endophytic bacterial species isolated from the root of Paris polyphylla Smith var. yunnanensis.

A Gram-negative, yellow-pigmented, rod-shaped bacterial strain YIM B02567T was isolated from the root of Paris polyphylla Smith var. yunnanensis in China. Strain YIM B02567T grew optimally at 25-30 °C and at pH 7.0 in the absence of NaCl on nutrient agar. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain YIM B02567T belong to the genus Chryseobacterium, and was closely related to Chryseobacterium piperi CTMT and Chryseobacterium soli DSM 19298T. Whole genome sequencing indicated that the genome size was 4,774,612 bp and with a G + C content of 34.5 mol%. Values of the ANI and the dDDH between strain YIM B02567T and its closely related Chryseobacterium species were below 81.72% and 24.7%. Strain YIM B02567T contained menaquinone-6 as the sole isoprenoid quinone, anteiso-C15:0, iso-C17:1 ω9c and iso-C17:0 3-OH as major fatty acids and phosphatidylethanolamine as major polar lipid. Based on the polyphasic analyses, strain YIM B02567T could be differentiated genotypically and phenotypically from recognized species of the genus Chryseobacterium. The isolate, therefore, represents a novel species, for which the name Chryseobacterium paridis sp. nov. is proposed. The type strain is YIM B02567T (= CGMCC 1.18657T).

A novel method for π-shaped esophagojejunostomy and double-tract reconstruction (DTR) as an alternative in totally laparoscopic or robotic proximal gastrectomy for treating upper third proximal early gastric cancer.

This study evaluated the impact of a new intracorporeal π-shaped esophagojejunostomy (EJS) and double-tract reconstruction (DTR) in totally laparoscopic and totally robotic proximal gastrectomy (TLPG or TRPG) for treating upper third early gastric cancer (U-EGC) in terms of intraoperative and short-term postoperative outcomes. Early proximal gastric cancer patients were identified based on a prospectively established database. From January 2017 to December 2018, these patients underwent intracorporeal π-shaped EJS and DTR after totally laparoscopic (n = 8) or robotic (n = 4) proximal gastrectomy (PG). We recorded and analyzed the baseline characteristics and surgical outcomes, including postoperative complications for these patients. No severe postoperative complications were observed following the operational procedures. Twelve patients (seven male and five female) diagnosed with cardia cancer (Siewert II and III) were enrolled, of which eight underwent the totally laparoscopic proximal gastrectomy (TLPG), and four underwent the totally robotic proximal gastrectomy (TRPG). The mean operative time, blood loss, day of the start of the diet, and postoperative hospital stay was 235.54 ± 20.79 min, 50.65 ± 35.44 mL, 3.85 ± 0.65 days, and 12.45 ± 3.24 days, respectively. All patients presented with a diagnosis of stage I gastric cancer. The mean number of lymph node dissections and the maximum tumor diameter was 13.91 ± 4.63 and 2.18 ± 0.73 cm, respectively. After the operational procedure, using the iodoethylene contrast reagent, we observed that a large proportion of iodoethylene contrast agents entered the jejunum directly, and a small proportion entered the jejunum through the duodenum. Surgeons followed up with ten patients for more than 12 months and the remaining two patients for more than 24 months. None of the patients showed any signs of anastomotic stenosis or reflux esophagitis or anemia symptoms. This study presents a novel method for π-shaped EJS and DTR as an alternative in TLPG or TRPG for treating proximal early gastric cancer, and it offers better short-term postoperative and intraoperative surgical outcomes.

Chronic REM-sleep deprivation induced laryngopharyngeal reflux in rats: A preliminary study.

OBJECTIVE: The aim of this study was to investigate the relationship of chronic REM-sleep deprivation with laryngopharyngeal reflux (LPR) and its mechanism. METHODS: Forty healthy male SD rats (body weight 250-280 g) were randomly divided into four groups. The first three ones were test group, which underwent REM-sleep deprivation with different duration of time by modified multiplatform water surface method. The last group was the control one having normal sleep. All the animals were performed Dx-pH monitoring when finishing sleep deprivation, and sacrificed to study the gastric residual rate (GRR) and small intestine peristalsis (SPR) rate by charcoal meal method. RESULTS: At prone position, the reflux incidence in the test groups fairly increased with the duration of sleep deprivation (p<0.05). The total number of reflux episodes at prone position in the test group rats with 3 months duration of sleep deprivation was significantly increased compared with that in the control ones (p<0.05). GRR in rats experiencing sleep deficiency for different duration all reduced significantly when compared to the control group (p<0.05). GRR and SPR presented continuous decline tendency with the duration of sleep deprivation (p>0.05). CONCLUSIONS: It is suggested that chronic sleep deficiency could cause LPR in rats, which might result from the uncoordinated digestive tract motility caused by dysfunction of central nervous system after chronic REM-sleep deprivation. Our results implied that chronic REM-sleep deprivation might be one of the causes of LPR. Addressing sleep problems might help to decrease the prevalence of LPR and enhance its treatment efficacy.

Paenibacillus paridis sp. nov., an endophytic bacterial species isolated from the root of Paris polyphylla Smith var. yunnanensis.

A Gram-reaction-positive, endospore-forming and rod-shaped bacterial strain, designated py1325T, was isolated from the root of Paris polyphylla Smith var. yunnanensis collected from Yunnan Province, PR China, and subjected to a polyphasic taxonomic characterization. It grew optimally with 0-1 % NaCl (w/v), at pH 7 and at 30 °C. The major respiratory quinone was MK-7 and the diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major cellular fatty acid was anteiso-C15 : 0. The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified phospholipids and two unidentified lipids. The results of 16S rRNA gene sequence analysis revealed the highest levels of sequence similarity with respect to Paenibacillus luteus R-3T (99.0 %), Paenibacillus sinopodophylli CCTCC AB 2016047T (97.9 %), Paenibacillus castaneae DSM 19417T (97.5 %) and Paenibacillus endophyticus LMG 27297T (97.2 %). The digital DNA-DNA hybridization and average nucleotide identity values between py1325T and these species ranged 20.6-53.3 % and 79.9-93.6 %. The G+C content of the genomic DNA was 47.7 mol%. According to the phylogenetic, phenotypic and chemotaxonomic evidence, strain py1325T clearly represents a novel species of the genus Paenibacillus, for which the name Paenibacillus paridis sp. nov. is proposed. The type strain is py1325T (=CCTCC AB 2015220T=LMG 29068T).

The correlation between NEDD4L and HIF-1α levels as a gastric cancer prognostic marker.

NEDD4L (neural precursor cell expressed developmentally down-regulated 4-like) protein is a member of ubiquitin ligases Nedd4 family. Although studies have shown that Nedd4L may act as a tumor suppressor in various cancers, including gastric cancer (GC), its clinical significance and the diagnostic value in GC is not well defined. HIF-1α (hypoxia inducible factor family of transcription factors) is actively involved in the metabolism of many tumors, although the relationship between its expression levels and clinical significance in GC still need to be established. In this study, the level of HIF-1α and NEDD4L mRNA and protein in 25 freshly frozen GC- and matched normal-tissues were determined by western blot and quantitative PCR (qPCR). Additionally, immunohistochemistry assay was performed to measure the protein level of NEDD4L and HIF-1α in 124 GC and 25 normal control tissues. We observed that the NEDD4L mRNA and protein levels decreased significantly (P < 0.001) in GC tissues, while that of HIF-1α increased (P < 0.001), and they both were associated with a poor prognosis, as was the case in patients with lower NEDD4L and higher HIF-1α expression (P < 0.001). On correlation analysis, a significantly negative relationship (r = 0.288, P < 0.01) was revealed between NEDD4L and HIF-1α expressions. Multivariate analysis revealed that co-expression of NEDD4L (P < 0.05) and HIF-1α (P < 0.001) were independent predictors of GC prognosis. Thus, the correlation of NEDD4L and HIF-1α levels may act as a prognostic marker of GC.

Robotic total gastrectomy with π-shaped esophagojejunostomy using a linear stapler as a novel technique.

OBJECTIVE: To evaluate the intraoperative and short-term postoperative outcomes of a novel robotic intracorporeal π-shaped esophagojejunostomy (EJS) after D2 total gastrectomy (TG) using the Da Vinci robotic surgical system for intracorporeal anastomosis after TG. BACKGROUND: Intracorporeal π-shaped EJS, using a linear stapler, was recently reported for laparoscopic total gastrectomy in patients with gastric cancer. However, robotic intracorporeal π-shaped EJS using a linear stapler has not been reported. This report aimed to describe the use of a novel technique for π-shaped EJS using the Da Vinci robotic system. METHODS: Robotic intracorporeal π-shaped esophagojejunostomy after total gastrectomy was performed in 11 consecutive patients diagnosed with early gastric cancer, and their perioperative outcomes were analyzed. RESULTS: All the operations were successful without conversion to open or laparoscopic surgery and postoperative complications. The total number of patients was 11 (7 males and 4 females). The mean age of the patients was 63.36 ± 10.56 years old. Seven patients were diagnosed with cardia cancer, 3 patients were diagnosed with gastric body cancer, and 1 patient was diagnosed with gastric antrum cancer. The patients' mean proximal resection margin was 3.18 ± 1.17 cm, the distal resection margin was 6.18 ± 1.40 cm, the mean length of the incision was 4.55 ± 0.69 cm, the mean operative time was 287.27 ± 30.69 min, the mean day of first flatus was 3.27 ± 0.79 days, the mean day of the start of diet was 2.91 ± 0.94 days, the mean postoperative hospital stay was 11.45 ± 5.13 days, and the mean operative blood loss was 47.27 ± 31.33 ml. No complications were observed during anastomosis, and the median anastomosis time was 19.5 min. The mean number of lymph node dissections was 17.91 ± 4.59, the mean number of positive lymph nodes was 0.45 ± 0.69, all patients were diagnosed with stage I-II gastric cancer, and the mean maximum diameter of the tumor was 2.67 ± 1.30 cm. All the patients had a smooth hospital discharge. CONCLUSION: A novel robotic gastrectomy with intracorporeal π-shaped EJS for esophagojejunal anastomosis described and shows acceptable resulted. This technique has the potential to offer better short-term surgical outcomes and overcomes the drawbacks of laparoscopy with a decreased risk of complications during and after surgery.

Upregulation of KIF20A correlates with poor prognosis in gastric cancer.

BACKGROUND: KIF20A is well known as one of the key proteins in mitosis. Recently, a number of studies illustrated that KIF20A might function as an oncogene in some carcinomas. However, its expression levels and clinical value remained unclear in gastric cancer (GC). PATIENTS AND METHODS: In this study, we investigated the expression of KIF20A in samples from GC patients and cell lines by quantitative real-time PCR and Western blot. The function of KIF20A in cell proliferation of GC cell lines was examined via cell viability and colony formation assays. Immunohistochemistry assay based on a tissue microarray consisting of 146 cases was performed to evaluate the prognostic value of KIF20A. The overall survival rate of 122 GC patients based on KIF20A expression was analyzed as well. Finally, using KIF20A inhibitor, genistein, and combining it with cisplatin or fluorouracil, the antitumor effects were studied. RESULTS: Most GC samples (56.76%) showed higher KIF20A expression level compared to their corresponding normal specimens, which demonstrated the potential oncogenic role of KIF20A in GC. The functional studies elucidated the essential role of KIF20A in GC cell proliferation. Besides, tissue microarray result showed that the expression level of KIF20A was significantly related to the histological grades (P=0.036). Furthermore, we found the expression of KIF20A was related to poor overall survival rate, which is coincident with the results from Kaplan-Meier plotter database. In addition, we found that a KIF20A inhibitor, genistein, could enhance the antitumor activity of cisplatin and fluorouracil, which might be considered as a chemosensitive agent in GC. CONCLUSION: KIF20A can promote cell proliferation in GC, which might be used as an independent prognostic factor and a potential therapeutic target.

Expression and Clinical Significance of ILF2 in Gastric Cancer.

The aim of this study is to investigate the expression levels and clinical significance of ILF2 in gastric cancer. The mRNA and protein expression levels of ILF2 were, respectively, examined by quantitative real-time PCR (qRT-PCR) and Western blot from 21 paired fresh frozen GC tissues and corresponding normal gastric tissues. In order to analyze the expression pattern of ILF2 in GC, 60 paired paraffin-embedded GC slides and corresponding normal gastric slides were detected by immunohistochemistry (IHC) assay. The correlation between ILF2 protein expression levels and clinicopathological parameters, overall survival (OS), disease-free survival (DFS), and clinical prognosis were analyzed by statistical methods. Significantly higher levels of ILF2 were detected in GC tissues compared with normal controls at both mRNA and protein level. High expression of ILF2 was tightly correlated with depth of invasion, lymph node metastasis, pathological stage, and histological differentiation. Log-rank test showed that high expression of ILF2 was positively associated with poor clinical prognosis. Multivariate analysis identified that ILF2 was an independent prognostic factor for OS and DFS. Our findings suggest that ILF2 may be a valuable biomarker and a novel potential prognosis predictor for GC patients.

Changes of ribbon synapses number of cochlear hair cells in C57BL/6J mice with age(Δ).

To investigate the changes of ribbon synapses (RS) number in cochlear hair cells in C57BL/6J mice with age. Basilar membranes within the cochlea of C57BL/6J mice aged 2, 6, 10 and 12 months were harvested (5 mice in each age group). The presynaptic and postsynaptic membranes were subject to double immunohistochemical staining and observed with a laser confocal microscope. The number of RS in each segment of basilar membrane was counted by using 3D reconstruction technique. Compared with 2-month-old mice, reduction of RS number in basilar membrane inside cochlea mainly occurred to the basal turn among C57BL/6J mice aged 6 months. The number of RS in each turn among 10-month-old mice decreased considerably, and such decrease continued in the top turn and middle turn in mice aged 12 months. In contrast, the number of RS in the basal turn increased slightly. Reduction of RS probably takes place in the early stage of C57BL/6J mice presbycusis. Early prevention of presbycusis can be achieved through measures to mitigate the reduction of RS.

MicroRNA-195 chemosensitizes colon cancer cells to the chemotherapeutic drug doxorubicin by targeting the first binding site of BCL2L2 mRNA.

The mechanisms underlying doxorubicin (Dox) resistance in colon cancer cells are not fully understood. MicroRNA (miRNA) play important roles in tumorigenesis and drug resistance. However, the relationship between miRNA and Dox resistance in colon cancer cells has not been previously explored. In this study, we utilized microRNA array and real-time PCR to verify that miR-127, miR-195, miR-22, miR-137 were significantly down-regulated, while miR-21, miR-592 were up-regulated in both HT29/DOX and LOVO/DOX cell lines. In vitro cell viability assay showed that knockdown of miR-195 in HT29 and LOVO cells caused a marked inhibition of Dox-induced cytotoxicity. Moreover, we explored that miR-195 is involved in repression of BCL2L2 expression through targeting its 3'-untranslated region, especially the first binding site within its mRNA. Furthermore, down-regulation of miR-195 conferred DOX resistance in parental cells and reduced cell apoptosis activity, while over-expression of miR-195 sensitized resistant cells to DOX and enhanced cell apoptosis activity, all of which can be partly rescued by BCL2L2 siRNA and cDNA expression. These results may have implications for therapeutic strategies aiming to overcome colon cancer cell resistance to Dox.

Acoustical stimulus changes the expression of stromal cell-derived factor-1 in the spiral ganglion neurons of the rat cochlea.

Neural stem cell (NSC) transplantation into the cochlea has been tested as a treatment for spiral ganglion neuron (SGN) degenerative disease and injury in various animal models. A recent study has shown evidence of functional recovery after transplantation of the stem cells into a degenerated-SGN model. Chemokine stromal cell-derived factor-1 (SDF-1, or known as CXC chemokine ligand-12, CXCL-12) signaling through CXCR4 has previously been identified as a key step in the homing of the stem cells within the injury areas; meanwhile, studies have revealed that the SDF-1/CXCR4 axis is also involved in axon guidance and pathfinding. A study found that transplanted neural precursor cells can migrate to the root of the auditory nerve when animals are subjected to an augmented acoustic environment (AAE). In accordance with these studies, we hypothesize that AAE will up-regulate the expression of SDF-1 in acoustic nerves. We tested our hypothesis by examining the expression of SDF-1 in different acoustic environments, and the results were confirmed by the auditory brainstem response (ABR), immunohistochemical and RT-PCR analyses. The results showed that SDF-1 was expressed at a relatively low level in the SGNs under normal animal unit acoustic conditions (40-50 dB). Moreover, it was significantly up-regulated in the SGNs under the 75 dB (augmented physiological process without hearing loss) and 90 dB AAE (pathological process with light hearing loss) conditions; however, under the 115 dB AAE (pathological process with severe hearing loss) condition, the expression of SDF-1 was not up-regulated. The results confirmed that appropriately augmented acoustical stimuli lead to the up-regulation of SDF-1, which may assist in the migration of the transplanted cells and the subsequent establishment of essential synaptic contacts between the exogenous cells and the host auditory pathway.

Wnt1 from cochlear schwann cells enhances neuronal differentiation of transplanted neural stem cells in a rat spiral ganglion neuron degeneration model.

Although neural stem cell (NSC) transplantation is widely expected to become a therapy for nervous system degenerative diseases and injuries, the low neuronal differentiation rate of NSCs transplanted into the inner ear is a major obstacle for the successful treatment of spiral ganglion neuron (SGN) degeneration. In this study, we validated whether the local microenvironment influences the neuronal differentiation of transplanted NSCs in the inner ear. Using a rat SGN degeneration model, we demonstrated that transplanted NSCs were more likely to differentiate into microtubule-associated protein 2 (MAP2)-positive neurons in SGN-degenerated cochleae than in control cochleae. Using real-time quantitative PCR and an immunofluorescence assay, we also proved that the expression of Wnt1 (a ligand of Wnt signaling) increases significantly in Schwann cells in the SGN-degenerated cochlea. We further verified that NSC cultures express receptors and signaling components for Wnts. Based on these expression patterns, we hypothesized that Schwann cell-derived Wnt1 and Wnt signaling might be involved in the regulation of the neuronal differentiation of transplanted NSCs. We verified our hypothesis in vitro using a coculture system. We transduced a lentiviral vector expressing Wnt1 into cochlear Schwann cell cultures and cocultured them with NSC cultures. The coculture with Wnt1-expressing Schwann cells resulted in a significant increase in the percentage of NSCs that differentiated into MAP2-positive neurons, whereas this differentiation-enhancing effect was prevented by Dkk1 (an inhibitor of the Wnt signaling pathway). These results suggested that Wnt1 derived from cochlear Schwann cells enhanced the neuronal differentiation of transplanted NSCs through Wnt signaling pathway activation. Alterations of the microenvironment deserve detailed investigation because they may help us to conceive effective strategies to overcome the barrier of the low differentiation rate of transplanted NSCs.

Stem cell transplantation via the cochlear lateral wall for replacement of degenerated spiral ganglion neurons.

Spiral ganglion neurons (SGNs) are poorly regenerated in the mammalian inner ear. Because of this, stem cell transplantation has been used to replace injured SGNs, and several studies have addressed this approach. However, the difficulty of delivering stem cells into the cochlea and encouraging their migration to Rosenthal's canal (RC), where the SGNs are located, severely restricts this therapeutic strategy. In this study, we attempted to establish a new stem cell transplantation route into the cochlea via the cochlear lateral wall (CLW). First, we tested the precision of this route by injecting Fluorogold into the CLW and next assessed its safety by mock surgeries. Then, using a degenerated SGN animal model, we transplanted neural stem cells (NSCs), derived from the olfactory bulb of C57BL/6-green fluorescent protein (GFP) mice, via the CLW route and examined the cells' distribution in the cochlea. We found the CLW transplantation route is precise and safe. In addition, NSCs migrated into RC with a high efficiency and differentiated into neurons in a degenerated SGN rat model after the CLW transplantation. This result revealed that the basilar membrane (BM) may have crevices permitting the migration of NSCs. The result of this study demonstrates a novel route for cell transplantation to the inner ear, which is important for the replacement of degenerated SGNs and may contribute to the treatment of sensorineural hearing loss.

Up-regulation of stromal cell-derived factor-1 enhances migration of transplanted neural stem cells to injury region following degeneration of spiral ganglion neurons in the adult rat inner ear.

Neural stem cell (NSC) transplantation into the cochlea is widely used for the treatment of spiral ganglion neuron (SGN) degenerative disease and injury in the animal models, but the migration of the transplanted NSCs to the injury region is difficult and the mechanism is still unclear. In this study, we aimed to validate whether the SGN-degenerated cochlear microenvironment plays a role in the NSC migration and investigated whether stromal cell-derived factor-1 (SDF-1) was involved in the NSCs migration. Using a rat SGN degeneration model, we demonstrated that the transplanted NSCs are more likely to migrate to the injury region during the early post-injury (EPI) than the late post-injury (LPI) stage and the control cochlea. We found that the expressions of SDF-1 increased transiently after SGN degeneration. Additionally, we showed that the NSCs express CXCR4, a receptor for SDF-1. We observed that the region to which the transplanted NSC localized coincides with the region where the SDF-1 is highly expressed following the degeneration of SGNs. Finally, we observed that the increased SDF-1 is derived from the Schwann cells in the SGN-degenerated model. These results suggest that SDF-1, which is derived from cochlear Schwann cells and up-regulated in the early injury microenvironment, plays a beneficial role in the NSC migration to the injury region. Optimizing SDF-1 expression in the host microenvironment or increasing the CXCR4 expression of the donor stem cells may improve the migration efficiency of transplanted cells toward the injury region in the cochlea.