Cell-Free Extracts from Human Fat Tissue with a Hyaluronan-Based Hydrogel Attenuate Inflammation in a Spinal Cord Injury Model through M2 Microglia/Microphage Polarization

Treatment for spinal cord injuries (SCIs) is often ineffective because SCIs result in a loss of nerve tissue, glial scar formation, local ischemia and secondary inflammation. The current promising strategy for SCI is the combination of bioactive materials and cytokines. Bioactive materials support the injured spinal cord, stabilize the morphology, and avoid excessive inflammatory responses. Fat extract (FE) is a cell-free liquid component containing a variety of cytokines extracted from human fat tissue using mechanical methods. In this research, a biocompatible HAMC (hyaluronan and methylcellulose) loaded with FE is used to treat a model of spinal cord contusion in mice. The composite not only inhibits death of neuro- and vascular cells and leads to the preservation of neural and vascular structure, but also modulates the inflammatory phenotype of macrophages in the locally injured region. Specifically, FE promotes the polarization of macrophages from an inflammatory M1 phenotype to an anti-inflammatory M2 phenotype. During the screening of the involved pathways, it is corroborated that activation of the STAT6/Arg-1 signaling pathway is involved in macrophage M2 polarization. In summary, FE is a promising treatment for SCI, as it is easy to obtain, nonimmunogenic, and effective.

[Recurrence and metastasis of pheochromocytoma/paraganglioma after tumor resection and clinical characteristics analysis]

Objective: The purpose of this study is to investigate the incidence of recurrence or metastasis of pheochromocytoma/paraganglioma (PPGL) patients after primary tumor resection, and to compare the differences of clinical indicators between patients with or without recurrence or metastasis. Methods: This study is a retrospective study. All 157 patients were followed up after tumor resection in Peking Union Medical College Hospital from 2008 to 2016. We obtained the basic information [age of diagnosis, gender, height, weight and body mass index (BMI)], the onset status of PPGL (age of onset, course of disease, family history, tumor location, whether the tumor is bilateral or multiple, and preoperative blood pressure), clinical and pathological features of PPGL tumor (tumor size, whether it could adhere, invade or infiltrate during operation, whether the tumor capsule is smooth and complete on the postoperative pathological diagnosis, whether there is infiltration growth and cystic necrosis on tumor pathology and Ki-67 index), and laboratory examination results [24 hours urinary norepinephrine (NE), epinephrine (E), dopamine (DA) before operation]. According to the outpatient or telephone follow-up, the postoperative incidences of recurrence and metastasis were explored, and the basic information, status of onset, clinical and pathological characteristics of tumors, and laboratory test results of patients were compared. Results: A total of 157 patients, 69 males and 88 females, were with an average age of (42.4±13.4) years old. There were 103 patients with PCC and 54 with PGL. The average follow-up time was (9.5±2.0) years. Of the 103 patients with PCC, 13 (12.6%) had postoperative recurrence and 9 (8.7%) had distant metastasis. Compared with the patients without recurrence and metastasis, the onset age of the 13 patients with recurrence was younger [(27.3±15.7) years vs (39.3±12.2) years, P=0.003], the course of disease was longer [48.0 (23.0, 141.0) months vs 12.0 (4.0, 60.0) months, P=0.010]. The tumor size of 9 patients with distant metastasis was larger [8.0 (6.1, 12.8) cm vs 5.0 (4.0, 7.0) cm, P=0.027]. Of the 54 patients with PGL, 8 (14.8%) had postoperative recurrence and 5 (9.3%) had distant metastasis. Compared with the patients without recurrence and metastasis, the course of disease of the 8 patients with recurrence was longer [90.0 (36.3, 165.0) months vs 24.0 (8.0, 72.0) months, P=0.009], and the proportion of primary tumors with multiple lesions was higher (4/8 vs 4.4%, P=0.003). The preoperative diastolic blood pressure was higher in 5 patients with distant metastasis [(146.0±32.1) mmHg vs (120.6±25.3) mmHg, P=0.043] (1 mmHg=0.133 kPa), and the proportion of primary tumors with multiple lesions was higher (2/4 vs 4.4%, P=0.029). Conclusion: PPGL patients are prone to have recurrence or metastasis. PPGL patients with postoperative recurrence or distant metastasis had younger onset age, longer course of disease, larger tumor size and higher proportion of multiple lesions.

Exosome-Transported circRNA_0000253 Competitively Adsorbs MicroRNA-141-5p and Increases IDD

The pathogenesis of intervertebral disc degeneration (IDD) is complex, and a better understanding of IDD pathogenesis may provide a better method for the treatment of IDD. Exosomes are 40-100 nm nanosized vesicles that are released from many cell types into the extracellular space. We speculated that exosome-transported circular RNAs (circRNAs) could regulate IDD. Exosomes from different degenerative grades were isolated and added to nucleus pulposus cells (NPCs), and indicators of proliferation and apoptosis were detected. Based on the previous circRNA microarray results, the top 10 circRNAs were selected. PCR was performed to determine the circRNA with the maximum upregulation. Competing endogenous RNA (ceRNA) analysis was carried out, and the sponged microRNA (miRNA) was identified. Further functional verification of the selected circRNA was carried out in vivo and in vitro. NPCs of different degenerative grades secreted exosomes, which could regulate IDD. circRNA_0000253 was selected as having the maximum upregulation in degenerative NPC exosomes. ceRNA analysis showed that circRNA_0000253 could adsorb miRNA-141-5p to downregulate SIRT1. circRNA_0000253 was confirmed to increase IDD by adsorbing miRNA-141-5p and downregulating SIRT1 in vivo and in vitro. Exosomal circRNA_0000253 owns the maximum upregulation in degenerative NPC exosomes and could promote IDD by adsorbing miRNA-141-5p and downregulating SIRT1.

CircularRNA_104670 plays a critical role in intervertebral disc degeneration by functioning as a ceRNA

This study was carried out to explore the roles of circular RNAs (circRNAs) in nucleus pulposus (NP) tissues in intervertebral disc degeneration (IDD). Differentially expressed circRNAs in IDD and normal NP tissues were identified based on the results of microarray analysis. Bioinformatics techniques were employed to predict the direct interactions of selected circRNAs, microRNAs (miR), and mRNAs. CircRNA_104670 was selected as the target circRNA due to its large multiplier expression in IDD tissues. After luciferase reporter and EGFP/RFP reporter assays, we confirmed that circRNA_104670 directly bound to miR-17-3p, while MMP-2 was the direct target of miR-17-3p. The receiver-operating characteristic (ROC) curve showed that circRNA_104670 and miR-17-3p had good diagnostic significance for IDD (AUC _{circRNA_104670} = 0.96; AUC _miRNA-17-3p = 0.91). A significant correlation was detected between the Pfirrmann grade and expression of circRNA_104670 (r = 0.63; p = 0.00) and miR-17-3p (r = −0.62; p = 0.00). Flow-cytometric analysis and the MTT assay showed that interfering with circRNA_104670 using small interfering RNA (siRNA) inhibited NP cell apoptosis (p < 0.01), and this inhibition was reduced by interfering with miR-17-3p. Interfering with circRNA_104670 suppressed MMP-2 expression and increased extracellular matrix (ECM) formation, which were also reduced by interfering with miR-17-3p. Finally, an MRI evaluation showed that circRNA_104670 inhibition mice had a lower IDD grade compared with control mice (p < 0.01), whereas circRNA_104670 and miRNA-17-3p inhibition mice had a higher IDD grade compared with circRNA_104670 inhibition mice (p < 0.05). CircRNA_104670 is highly expressed in the NP tissues of IDD and acts as a ceRNA during NP degradation.

‘RNA sponges’ may provoke lower back pain by soaking up regulatory RNAs that normally protect the protein infrastructure surrounding cells in intervertebral discs. Many people suffer from lower back pain arising from disc degeneration (IDD). A team led by Fei-Zou and Jian-Yuan Jiang at Fudan University, Shanghai, China set out to identify molecular mechanisms that might contribute to IDD. They focused on circular RNAs, non-protein coding RNAs that have been linked to a variety of diseases. The researchers learned that IDD is associated with strongly elevated expression of a circular RNA that acts as an ‘RNA sponge’, binding to and thereby inactivating other RNA molecules. This inactivation ultimately results in the excessive production of an enzyme that can damage the protein matrix that supports cells within spinal discs, potentially setting up the conditions for IDD.

Cortical Activation Changes in Hirayama Disease After Anterior Cervical Decompression and Fusion

BACKGROUND

Spinal cord injury may cause cortical reconstruction. We, therefore explored the changes in cortical activation before and after anterior cervical decompression and fusion surgery in patients with Hirayama disease (HD).

METHODS

In total, 17 cases with HD underwent anterior cervical decompression and fusion surgery. Blood oxygenation level-dependent functional magnetic resonance imaging scan was performed preoperatively, 3 months, 6 months, and 1 year after surgery. Activated voxels were compared between both hands after adjusting for head motion, slice timing, spatial normalization, and image smoothing. Grip strength also was tested in both hands.

RESULTS

A retrospective review indicated that the grip strength of the asymptomatic hand was significantly stronger than the symptomatic hand at the time point before the surgery, 3 months after surgery, 6 months after surgery, and 1 year after surgery (P < 0.001). The grip strength of both symptomatic and asymptomatic hands continuously increased within 6 months after surgery (P < 0.05), but it stopped at 1 year after the surgery. The symptomatic limb tends to produce bilateral activation in the primary motor area (M1) during motor tasks. Both contralateral and ipsilateral M1 activation were stronger in symptomatic hand tasks preoperatively (P < 0.05). Both contralateral and ipsilateral activation in M1 during symptomatic hand tasks began to reduce after surgery, and statistical significance was observed 6 months after surgery (P < 0.05). Contralateral activation was relatively even over 6 months of the surgery (P > 0.05).

CONCLUSIONS

After surgery, pathologic reconstruction may have occurred in the primary motor cortex. Recovery of motor function in the symptomatic limb was accompanied by decreased ipsilateral and contralateral M1 activation, as well as symptom improvement. These findings suggested that postoperative cortical activation changes may reflect functional recovery in HD.

The value of radiographic indexes in the diagnosis of discogenic low back pain: a retrospective analysis of imaging results

To explore value of different radiographic indexes in the diagnosis of discogenic low back pain (LBP). A total number of 120 cases (60 patients diagnosed with discogenic LBP and 60 healthy people) were retrospectively analysed to identify factors in the diagnosis of discogenic LBP by using univariate and multivariate analyses. A receiver operating characteristic (ROC) curve was drew to show the predictive accuracy of the finally enrolled factors. Among all the included patients, 60 were strictly admitted in the discogenic LBP group while the other 60 were enrolled in the control group. Five results shows significant differences between discogenic LBP and control groups, including Cobb angle, lumbar stability, height of the disc, Modic change and High intense zone (HIZ) based on the results of univariate analysis; lumbar stability, Modic change and HIZ show high value in the diagnosis of lumbar discogenic pain based on the multivariate logistic analysis. The ROC curve shows that good diagnostic accuracy was obtained from the enrolled diagnostic factors including lumbar stability (Angular motion, more than 14.35°), Modic change and HIZ.

Can an Endplate-conformed Cervical Cage Provide a Better Biomechanical Environment than a Typical Non-conformed Cage?: A Finite Element Model and Cadaver Study

OBJECTIVES

To evaluate the biomechanical characteristics of endplate-conformed cervical cages by finite element method (FEM) analysis and cadaver study.

METHODS

Twelve specimens (C2 -C7 ) and a finite element model (C3 -C7 ) were subjected to biomechanical evaluations. In the cadaver study, specimens were randomly assigned to intact (I), endplate-conformed (C) and non-conformed (N) groups with C4-5 discs as the treated segments. The morphologies of the endplate-conformed cages were individualized according to CT images of group C and the cages fabricated with a 3-D printer. The non-conformed cages were wedge-shaped and similar to commercially available grafts. Axial pre-compression loads of 73.6 N and moment of 1.8 Nm were used to simulate flexion (FLE), extension (EXT), lateral bending (LB) and axial rotation (AR). Range of motion (ROM) at C4-5 of each specimen was recorded and film sensors fixed between the cages and C5 superior endplates were used to detect interface stress. A finite element model was built based on the CT data of a healthy male volunteer. The morphologies of the endplate-conformed and wedge-shaped, non-conformed cervical cages were both simulated by a reverse engineering technique and implanted at the segment of C4-5 in the finite element model for biomechanical evaluation. Force loading and grouping were similar to those applied in the cadaver study. ROM of C4-5 in group I were recorded to validate the finite element model. Additionally, maximum cage-endplate interface stresses, stress distribution contours on adjoining endplates, intra-disc stresses and facet loadings at adjacent segments were measured and compared between groups.

RESULTS

In the cadaver study, Group C showed a much lower interface stress in all directions of motion (all P < 0.05) and the ROM of C4-5 was smaller in FLE-EXT (P = 0.001) but larger in AR (P = 0.017). FEM analysis produced similar results: the model implanted with an endplate-conformed cage presented a lower interface stress with a more uniform stress distribution than that implanted with a non-conformed cage. Additionally, intra-disc stress and facet loading at the adjacent segments were obviously increased in both groups C and N, especially those at the supra-jacent segments. However, stress increase was milder in group C than in group N for all directions of motion.

CONCLUSIONS

Endplate-conformed cages can decrease cage-endplate interface stress in all directions of motion and increase cervical stability in FLE-EXT. Additionally, adjacent segments are possibly protected because intra-disc stress and facet loading are smaller after endplate-conformed cage implantation. However, axial stability was reduced in group C, indicating that endplate-conformed cage should not be used alone and an anterior plate system is still important in anterior cervical discectomy and fusion.

[Radiographic assessment of vertebral artery injury in anterior cervical surgery in healthy adults]

Objectives: To study the relationship between the anatomical parameters of transverse foramen and intervertebral discs in the cross-section of the cervical spine in healthy adults, and to evaluate the risk of vertebral artery injury in the anterior cervical spine surgery. Methods: There were 24 healthy adults(12 male, 12 female) underwent neck CT angiography with clear vertebral artery and the adjacent structure imaging from June to December 2014 in Huashan Hospital, Fudan University. The anatomical parameters of vertebral artery V2 segment with lower cervical vertebrae and intervertebral discs were measured by cross-sectional images of C(3-6). The corresponding parameters of different sex and both sides of the same segment were analyzed by independent samples t-test and paired t test, respectively. The least significant difference(LSD) t test was used to compare the corresponding data between different segments. Results: The vertebral artery was not walking in the middle of the transverse foramen in healthy individual, but partial medial, partial front walking. Transverse diameter of transverse foramen in male and female were 6.62-6.89 mm and 6.21-6.45 mm, and sagittal diameter was 5.41-6.48 mm and 5.40-6.10 mm, respectively.The transverse foramen were slightly oval. The distance between vertebral artery and midline in male and female were 14.23-16.12 mm and 13.60-15.04 mm, respectively, which was much larger than the width of cervical vertebral corpectomy. Compared with C(3-4), intervertebral disc, the transverse distance between the vertebral artery and the uncovertebral joint of C(4-5), C(5-6) was smaller, and the distance from the vertebral artery to the posterior margin of the uncovertebral joint was relatively small, the difference was statistically significant (t=2.449, P=0.022). The distance from vertebral artery to the posterior margin of uncinate process was 1/5-2/5 of the distance between the anterior and posterior edge of the corresponding segmental vertebra. Conclusion: Based on this anatomical study, the risk of vertebral artery injury in conventional anterior cervical decompression is small, and the risk of vertebral artery injury in different segments is slightly different.

Mast Quadrant-assisted minimally invasive modified transforaminal lumbar interbody fusion: single incision versus double incision

BACKGROUND

The concept of minimally invasive techniques is to make every effort to reduce tissue damage. Certainly, reducing skin incision is an important part of these techniques. This study aimed to investigate the clinical feasibility of Mast Quadrant-assisted modified transforaminal lumbar interbody fusion (TLIF) with a small single posterior median incision.

METHODS

During the period of March 2011 to March 2012, 34 patients with single-segment degenerative lumbar disease underwent the minimally invasive modified TLIF assisted by Mast Quadrant with a small single posterior median incision (single incision group). The cases in this group were compared to 37 patients with single-segment degenerative lumbar disease in the double incision group. The perioperative conditions of patients in these two groups were statistically analyzed and compared. The Oswestry Disability Index (ODI) scores, Visual Analog Scale (VAS) scores, and sacrospinalis muscle damage evaluation indicators before operation and 3, 12 months postoperation were compared.

RESULTS

A total of 31 and 35 cases in the single incision and double incision groups, respectively, completed at least 12 months of systemic follow-up. The differences in perioperative conditions between the two groups were not statistically significant. The incision length of the single incision group was significantly shorter than that of the double incision group (P < 0.01). The ODI and VAS scores of patients in both groups improved significantly at 3 and 12 months postoperation. However, these two indicators at 3 and 12 months postoperation and the sacrospinalis muscle damage evaluation indicators at 3 months postoperation did not differ significantly between the two groups (P ≥ 0.05).

CONCLUSIONS

Mast Quadrant-assisted modified TLIF with a small single posterior median incision has excellent clinical feasibility compared to minimally invasive TLIF with a double paramedian incision.

De novo DNA methylation of the paternal genome in 2-cell mouse embryos

The developmental dynamics of DNA methylation events have been well studied. Active demethylation of the paternal genome occurs in the zygote, passive demethylation occurs during cleavage stages, and de novo methylation occurs by the blastocyst stage. It is believed that the paternal genome has lower levels of methylation during early development than the maternal genome. However, in this study, we provide direct and indirect evidence of genome-wide de novo DNA methylation of the paternal genome after the first cell cycle in mouse embryos. Although very little methylation was detected within the male pronucleus in zygotes, an intense methylation signal was clearly visible within the androgenetic 2-cell embryos. Moreover, the DNA methylation level of the paternal genome in the post-zygotic metaphase embryos was similar to that of the maternal genome. Using indirect immunofluorescence with an antibody to methylated lysine 9 in histone H3, we provided new evidence to support the concept of spatial compartmentalization of parental genomes in 2-cell mouse embryos. Nevertheless, the transient segregation of parental genomes was not observed by determining the DNA methylation distribution in the 2-cell embryos even though DNA methylation asymmetry between the maternal and paternal pronucleus existed in the 1-cell stage. The disappearance of separate immunofluorescence signals of 5-methyl cytosine in the 2-cell embryos might be attributed to the de novo methylation of the paternal genome during the first mitotic cycle.

Hydroxysafflor yellow A suppresses liver fibrosis induced by carbon tetrachloride with high-fat diet by regulating PPAR-γ/p38 MAPK signaling

CONTEXT

One approach to protect against liver fibrosis is the use of herb-derived natural compounds, such as hydroxysafflor yellow A (HSYA). The antifibrosis effect of HYSA against liver fibrosis has been investigated; however, its mechanisms have not yet been entirely revealed.

OBJECTIVES

To study the protective effects of HSYA on liver fibrosis induced by carbon tetrachloride (CCl4) and a high-fat diet (HFD), and to determine the mechanism of action of HSYA.

MATERIALS AND METHODS

CCl4 and HFD were used to mimic liver fibrosis in rats, and serum biochemical indicators were determined. The antifibrosis effects of HSYA were evaluated and its mechanisms were investigated by histopathological analysis, immunohistochemical staining, enzyme-linked immunosorbent assays, real-time-PCR, and western blotting.

RESULTS

HSYA reduced CCl4- and HFD-mediated liver fibrosis and ameliorated serum biochemical indicator, downregulated the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) (0.31 ± 0.03 protein, 0.59 ± 0.02 mRNA) and transformin growth factor-β1 (TGF-β1) (0.81 ± 0.02 protein, 0.58 ± 0.04 mRNA), and upregulated the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) (1.57 ± 0.13 protein, 2.48 ± 0.19 mRNA) and matrix metallopeptidases-2 (MMP-2) (2.31 ± 0.16 protein, 2.79 ± 0.22 mRNA) (p < 0.01, versus model group). These effects were significantly attenuated by PPAR-γ antagonist GW9662 via blocking the phosphorylation of p38 MAPK.

DISCUSSION AND CONCLUSION

These data demonstrate a novel role for HSYA in inhibiting CCl4- and HFD-mediated liver fibrosis, and reveal that PPAR-γ and p38 MAPK signaling play pivotal roles in the prevention of liver fibrosis induced by CCl4 and HFD.

Changes in the expression of Fox O1 and death ligand genes during follicular atresia in porcine ovary

Follicular atresia, a key phenomenon in follicle development, eliminates most of the follicles in mammalian ovaries. To investigate the molecular mechanism of follicular atresia in porcine ovaries, we investigated the mRNA expression of three important cell death ligand-receptor systems and Fox O1 in follicles with a diameter of 3-5 mm. The phosphorylation and subcellular localization of Fox O1 during granulosa cell apoptosis was also determined. TRAIL and Fas L played an important role in follicular atresia at this stage. Fox O1 expression was upregulated during atresia, and was confined to the nucleus of granulosa cells; however, phosphorylated Fox O1 was localized to the cytoplasm. These results suggest Fox O1 involvement in the regulation of TRAIL and Fas L expression during follicular atresia in pigs.

Localization and expression of histone H2A variants during mouse oogenesis and preimplantation embryo development

Epigenetic modifications of the genome, such as histone H2A variants, ensure appropriate gene activation or silencing during oogenesis and preimplantation embryo development. We examined global localization and expression of the histone H2A variants, including H2A.Bbd, H2A.Z and H2A.X, during mouse oogenesis and preimplantation embryo development. Immunocytochemistry with specific antibodies against various histone H2A variants showed their localization and changes during oogenesis and preimplantation development. H2A.Bbd and H2A.Z were almost absent from nuclei of growing oocytes (except 5-day oocyte), whereas H2A.X was deposited in nuclei throughout oogenesis and in preimplantation embryos. In germinal vesicle (GV) oocyte chromatin, H2A.Bbd was detected as a weak signal, whereas no fluorescent signal was detected in GV breakdown (GVBD) or metaphase II (MII) oocytes; H2A.Z showed intense signals in chromatin of GV, GVBD and MII oocytes. H2A. Bbd showed very weak signals in both pronucleus and 2-cell embryo nuclei, but intense signals were detected in nuclei from 4-cell embryo to blastula. The H2A.Z signal was absent from pronucleus to morula chromatin, whereas a fluorescent signal was detected in blastula nuclei. Our results suggest that histone H2A variants are probably involved in reprogramming of genomes during oocyte meiosis or after fertilization.

Evaluation of characteristics and surgical outcomes in cervical spondylotic amyotrophy

BACKGROUND

Cervical spondylotic amyotrophy (CSA) is a rare clinical syndrome resulting from cervical spondylosis. Surgical treatment includes anterior cervical decompression and fusion (ACDF), and laminoplasty with or without foraminotomy. Some studies indicate that ACDF is an effective method for treating CSA because anterior decompression with or without medial foraminotomy can completely eliminate anterior and/or anterolateral lesions. We retrospectively evaluated outcome of surgical outcome by anterior cervical decompression and fusion (ACDF).

MATERIALS AND METHODS

28 CSA patients, among whom 12 had proximal type CSA and 16 had distal type CSA, treated by ACDF, were evaluated clinicoradiologically. The improvement in atrophic muscle power was assessed by manual muscle testing (MMT) and the recovery rate of the patients was determined on the basis of the Japanese Orthopedic Association (JOA) scores. Patient satisfaction was also examined.

RESULTS

The percentage of patients, who gained 1 or more grades of muscle power improvement, as determined by MMT, was 91.7% for those with proximal type CSA and 37.5% for those with distal type CSA (P < 0.01). The JOA score-based recovery rates of patients with proximal type and distal type CSA were 60.8% and 41.8%, respectively (P < 0.05). Patient satisfaction was 8.2 for those with proximal type CSA and 6.9 for those with distal type CSA (P < 0.01). A correlation was observed among the levels of improvement in muscle power, JOA score based recovery rate, patient satisfaction and course of disease (P < 0.05).

CONCLUSION

ACDF can effectively improve the clinical function of patients with CSA and result in good patient satisfaction despite the surgical outcomes for distal type CSA being inferior to those for proximal type CSA. Course of disease is the fundamental factor that affects the surgical outcomes for CSA. We recommend that patients with CSA undergo surgical intervention as early as possible.

Generation of induced pluripotent mouse stem cells in an indirect co-culture system

Typically, production of induced pluripotent stem cells requires direct contact with feeder cells. However, once the stem cells have reached the appropriate maturation point, it is difficult to separate them from feeder cells, which must be irradiated with γ-rays or treated with the antibiotic mitomycin-C. We used a microporous poly-membrane-based indirect contact co-culture system with mouse embryonic fibroblasts to induce mouse pluripotent stem cells without radiation or antibiotics. We found that induced pluripotent stem cells induced by this co-culture method had a reprogramming efficiency and time similar to those induced using traditional methods. Furthermore, strongly expressed pluripotent markers showed a normal karyotype and formation and contained all three germ layers in a teratoma.