1.Trans-facet joints approach to treat thoracic degenerative diseases with anterior compression
Xuexiao MA ; Bohua CHEN ; Yan ZHANG ; Guoqing ZHANG ; Yougu HU
Chinese Journal of Orthopaedics 2010;30(11):1068-1072
Objective To investigate the clinical outcomes of trans-facet joints approach to treat thoracic degenerative disease with anterior compression.Methods From January 2003 to December 2009,22 patients with thoracic myelopathy caused by anterior compression were studied retrospectively.The patients included 16 males and 6 females,aged from 36 to 72 years(average 54.2 years).There were thoracic ossification of posterior longitudinal ligament(OPLL)in 11 cases,thoracic disc protrusion with ossification in 8 cases,thoracic vertebra posterior osteophytes in 2 cases,ankylosing spondylitis with thoracic pseudoarthrosis in 1 cases.Preoperative Japanese Orthopaedic Association(JOA)score was 5.2(range,2-9).The characteristic of thoracic degeneration was analyzed by CT and MRI examination.Posterior decompressive laminectomies were performed by the technique of "cap uncovering".The facet joints were removed bilaterally.Anterior ossified compressions were cut via posterior-lateral approach,and then intervertebral bone graft and bilateral pedicle screws were implanted.Results All patients were followed up for 8 to 38 months.According to the revised Epstein standard,there were excellent in 7 patients,good in 9,fair in 4,and poor in 2.The total effective rate was 90.9%(20/22).The excellent and good rate was 72.7%(16/22).The mean postoperative JOA score was 8.7(range,2-11).Surgical complications included dural laceration in 1 patient,pleura injury in 1 patient,epidural hematoma in 2 patients.There were no cases of spinal instability or deep infection.Conclusion The anterior compression can be solved completely via trans-facet joints approach in thoracic degenerative disease patients.
2.The effect of degassing and peroxidation on the metal-ceramic bonding strength of Pd-Ag alloy
Bohua LI ; Jiantao YE ; Yonggong WANG ; Demin YAN ; Maiquan WANG ; Ming HOU
Journal of Practical Stomatology 2015;(2):200-204
Objective:To investigate the effect of degassing and peroxidation on metal-ceramic bonding strength of Pd-Ag alloy. Methods:The metal-ceramic interface of group A (peroxidation)and B (degassing)was investigated under scanning electronic micro-scope(SEM)and energy dispersive spectrum (EDS).The bond strength between metal and ceramics was measured using a three-point bend test according to ISO9693.Results:The formation of nodules on the surface of alloy specimens was observed in both groups by SEM.The nodules on the specimens of group A were more densely than those of group B.The diameter of nodules in group B was 1 .5μm approximately.The interface of the metal-ceramic specimens had a clear transition porcelain layer and no hole or slit was present. The mean bonding strength of group A and B was (45.97 ±3.92)MPa and (49.1 1 ±6.42)MPa respectively(P=0.031 ).Conclu-sion:Degassing can improve metal-ceramic bonding strength of Pd-Ag alloy significantly.
3.Antidepressant-like effects of ammoxetine in mice of behavioral despair model and monoamine neurotransmitter depletion model
Yan GUO ; Rui XUE ; Tingting ZHANG ; Qiongyin FAN ; Yunfeng LI ; Bohua ZHONG ; Youzhi ZHANG
Chinese Journal of Pharmacology and Toxicology 2016;30(5):498-503
OBJECTIVE To study the antidepressant effects of ammoxetine(AMX)and the underlying mechanisms. METHODS Two behavioral despair models,the tail suspension test (TST) and the forced swimming test(FST),were used to evaluate the antidepressant-like effects of AMX 2.5-20 mg · kg-1 following oral administration. Monoamine neurotransmitter p-chloro-phenylalanine(p-CPA)andα-methyl-p-tyrosine(AMPT) depletion models in mice were used to investigate the effects of AMX on levels of 5-serotomin(5-HT)and norepinephrine(NE)in the brain. RESULLTS The results of behavioral study showed that compared with normal control group,AMX(10 and 20 mg · kg-1)reduced the immobility time of mice by 51.4% and 80.7% in the TST(P<0.05,P<0.01) or by 48.0% and 66.2% in the FST (P<0.05),respectively. Locomotion activity test indicated that AMX did not increase or decrease the movement distance of mice,demonstrating that AMX had no excitatory or inhibitory actions on the central nervous system. Moreover,AMX(5,10 and 20 mg·kg-1)exerted antidepressant effects in the p-CPA induced 5-HT depletion model and AMPT induced NE depletion model,as evidenced by the significantly reduced immobility time,ie,63.9%,93.4%,90.5% and 61.9%,77.2%,100% reduction in the TST (P<0.01),respectively,and AMX at the dose of 20 mg·kg-1 significantly increased the concentrations of 5-HT and NE by 144.7% and 57.2% in the mouse brain(P<0.05) ,respectively. CONCLUSION AMX has strong antidepressant-like effects in behavioral despair models and monoamine neurotransmitter depletion models in mice,which is involved in the increased levels of 5-HT and NE in the brain.
4.Clinical treatment of suprascapular nerve compression syndromes via posterior portal by arthroscopic decompression of spinoglenoid notch cysts and release of suprascapular nerve
Weijie LIU ; Yan CAI ; Chao QI ; Tengbo YU ; Bohua CHEN ; Xia ZHAO ; Jian WANG
Chinese Journal of Orthopaedics 2018;38(7):390-395
Objective To investigate the clinical outcomes of arthroscopic decompression of spinoglenoid notch cysts and release of suprascapular nerve in treating suprascapular nerve compression syndromes via posterior portal.Methods Eleven patients from January 2010 to January 2017 with spinoglenoid notch cysts complicated suprascapular nerve compression syndromes were included.There were 7 males and 4 females with the average age of 41.5±5.3 years old (range 29-56 years) with 3 patients left side involved and 8 right side.All patients were diagnosed with MRI and EMG.The surgical procedure began with posterior capsule arthroscopic releasement from the labmm,then found the spinoglenoid notch cyst.Split of the cyst was made for internal drainage,then found the suprascapular nerve and vessel bundle for clearing the bursal tissue with probe,decompressed the suprascapular nerve finally.Mecobalamin was taken (0.5 mg,tid) until 3 months postoperatively.The patients were evaluated by functional scores from American Shoulder Elbow Surgeons (ASES) and Constant-Murley preoperatively and postoperatively.Statistical analysis was conducted by student t-test.Results All patients were followed up at 7-15 months (with an average of 10 months).The mean preoperative ASES score increased from 46.5±3.7 to 93.8±2.2 at the time of final follow-up with the significant difference (t=3.359,P<0.05).Preoperative ASES score were good in 5 cases,fair in 4 cases and poor in 2 cases.The postoperative score were excellent in all patients.The Constant-Murley score was 47.3±4.2 preoperatively and 94.0±1.8 postoperatively with significant difference (t=4.776,P<0.05).Preoperative score were good in 6 cases and fair in 5 cases.The postoperative score were excellent in all patients.These patients had no recurrence of cyst after surgery and returned to work.Conclusion Arthroscopic decompression of spinlglenoid notch cyst and suprascapular nerve release via posterior portal can successfully treat suprascapular nerve compression syndrome resulting in spinoglenoid notch cyst.
5.Advances in the treatment of intervertebral disc degeneration by stem cell exosomes
Weiliang SU ; Xiaolin WU ; Zhu GUO ; Nana SHEN ; Chang LIU ; Shuai YANG ; Yan WANG ; Guoqing ZHANG ; Wujun CHEN ; Hongfei XIANG ; Bohua CHEN
Chinese Journal of Orthopaedics 2021;41(4):253-261
Exosomes are vesicles with a double globular membrane of lipids that can be secreted by a variety of cells, including stem cells. Exosomes have unique biological characteristics and irreplaceable powerful functions which play an important role in intercellular communication. The various cytokines, signal proteins, lipids and regulatory nucleic acids contained in stem cell exosomes can play a protective role against the injury of kidney, liver, heart, blood vessels and nerves. Stem cell exosomes delay the process of intervertebral disc degeneration by inhibiting the apoptosis of nucleus pulposus cells and increasing the synthesis of extracellular matrix, etc. The mechanism of its role is mainly through miRNA and related signaling pathways. Exosomes contain complex components. Although the mechanism of action of exosomes in intervertebral discs has been preliminarily explored, the components contained in exosomes are complex and the specific situation has not been fully understood, which still needs further study. In this review, the characteristics and functions of stem cell exosomes, extraction, identification and storage methods, the impacttovarious other tissues, as well as the effects on intervertebral discs and their mechanisms were elaborated in order to provide a basis for the study of intervertebral disc degenerative diseases.
6.Effect of robot navigation system combined with 3D printing in assisting percutaneous vertebroplasty for Kümmell disease
Liang LI ; Liang YAN ; Bohua CHEN ; Wenyuan DING ; Qixin CHEN ; Yue ZHU ; Zhongliang DENG ; Baorong HE
Chinese Journal of Trauma 2020;36(9):797-803
Objective:To compare the effect of robot navigation system (Tian Ji robot system) plus 3D printing and traditional C-arm X-ray fluoroscopy in assisting percutaneous kyphoplasty (PKP) or percutaneous vertebroplasty (PVP) for treatment of Kümmell disease.Methods:A retrospective case-control study was conducted to analyze the clinical data of 40 patients with Kümmell disease treated at Honghui Hospital Affiliated to Xi'an Jiaotong University School of Medicine from December 2017 to February 2019, including 12 males and 28 females, with an average age of 56.4 years (range, 42-71 years). In observation group, 20 patients underwent PKP or PVP assisted by the robot navigation system and 3D printing. In control group, 20 patients underwent PKP or PVP assisted by the traditional C-arm X-ray fluoroscopy. The operation time and incidence of complications were observed. The visual analogue scale (VAS), Oswestry disability index (ODI), Cobb angle and anterior vertebral height were compared before operation, 1 day and 3 months after operation.Results:All patients were followed up for 3.5-8.6 months (mean, 6.7 months). The operation time in control group was (32.2±5.8)minutes, compared with (26.7±3.6)minutes in observation group ( P<0.05). The incidence of cement leakage was 0% (0/20) in the observation group and 5% (1/20) in control group ( P>0.05). One day after operation, in observation group and control group, the VAS was (2.1±0.3)points and (3.7±0.8)points, the ODI was 14.3±1.8 and 25.5±5.7, the Cobb angle was (20.6±1.2)° and (22.4±0.6)°, and the anterior height of vertebral body was (21.2±0.8)mm and (17.6±0.7)mm, respectively, showing significant improvement compared with those before operation ( P<0.01). Three months after operation, in observation group and control group, the VAS was (1.8±0.4)points and (2.8±0.8)points, the ODI was 12.3±1.5 and 21.6±2.3, the Cobb angle was (18.1±0.8) ° and (20.5±1.6)°, and the anterior height of vertebral body was (20.1±1.8)mm and (16.8±1.3)mm, showing no significant difference compared with those at day 1 after operation ( P>0.05). There were significant differences in the VAS, ODI, Cobb angle and anterior vertebral height between the two groups 1 day and 3 months after operation ( P<0.01). Conclusion:For Kümmell disease, with assistance with the robot navigation system combined with 3D printing, PKP or PVP can more effectively reduce the pain of patients, improve the quality of life, restore the anterior height of vertebral body, and realize the individualized treatment in comparison with the traditional C-arm X-ray fluoroscopy.
7.Management strategy and indications for revisionary internal fixation after percutaneous kyphoplasty/ percutaneous vertebroplasty in cancellous vertebral fractures
Xiaolin WU ; Hongfei XIANG ; Guoqing ZHANG ; Wenyuan DING ; Zhu GUO ; Yan WANG ; Chi ZHANG ; Ronghuan WANG ; Yougu HU ; Yingze ZHANG ; Bohua CHEN
Chinese Journal of Orthopaedic Trauma 2019;21(8):649-657
Objective To explore the management strategy and indications for revisionary internal fixation after percutaneous kyphoplasty/percutaneous vertebroplasty (PKP/PVP) in cancellous vertebral fractures.Methods A retrospective analysis was made of the 676 cases of single-segment PKP/PVP at Department of Orthopaedics,The Affiliated Hospital to Qingdao University from January 2008 to January 2019.They were subjected to 4 different managements after their primary PKP/PVP:rehabilitation without any treatment in 637 cases,conservative treatment in 19 cases (including 3 ones who refused any revision),KP/VP revision in 12 cases and internal fixation revision in 8 cases.The rate of volume reduction after bone cement dispersion (Vx) was calculated using software Mimics 17.0 on the basis of primary CT data of all the patients.The correlation regression analysis was made between the revision rate and the approximate quantization value of Vx.The Glasgow Coma Score (GCS) of conscious state was used to evaluate the 39 patients after failure of their primary surgery before the surgical strategy for revision was worked out.The cobb angle,pelvic incidence angle (PI),pelvic inclination angle (PT),sacral inclination angle (SS),sagittal deviation (SVA),pain visual analogue scale (VAS) were measured and recorded before operation and at the last follow-up for the KP/VP revision group and internal fixation revision group,indicated as △cobb,△PI,△PT,△SS,△SVA and △VAS,respectively.The indexes were compared between the 2 groups.Results The incidence of osteoporotic vertebral fractures treated with internal fixation revision was 1.18% (8/676).The correlation between Vx and revision rate was y =0.53 + 0.04x (P < 0.05).The regression analysis showed that Vx was positively correlated with the revision rate (r2 =0.860,P =0.001) and the fitting curve was correlated (r2 =0.916,P =0.001).The GSC scores revealed 31 normal,6 mild disturbance and 2 moderate disturbance cases.There were no significant differences in gender,age or VAS scores between the KP/VP revision group and the internal fixation revision group (P > 0.05).There was a significant difference in △cobb between the 2 revision groups (6.3° ± 7.5° versus 19.2° ± 14.8°) (P <0.05),but there were no significant differences between the 2 groups in △PI (4.1°±5.2° versus 3.3°±6.7°),△PT (0.7°±4.6° versus 0.4° ± 3.2°),△SS (3.7° ± 6.2° versus 3.1° ± 5.3°) or △SVA (-3.2 ± 11.9 mm versus-7.9 ± 9.5 mm) (P > 0.05).Conclusions The outcomes of primary PKP/PVP have a great impact on the decision-making of internal fixation revision.The mode and extent of diffusion after initial vertebral cement perfusion are particularly related to the revision rate.The revision plan should depend on clinical symptoms.The internal fixation revision should be individualized to ensure the quality of life of the patients in line with the principles of "resolving symptoms" and "moderate correction".
8.Comparison of Iso-C 3D navigation system versus X-ray fluoroscopy in minimally invasive surgery for Kümmell disease
Liang LI ; Dingjun HAO ; Liang YAN ; Songchuan ZHAO ; Lin GAO ; Bohua CHEN ; Baorong HE
Chinese Journal of Orthopaedic Trauma 2019;21(8):658-664
Objective To compare the Iso-C 3D navigation system versus the traditional X-ray fluoroscopy in minimally invasive surgery for Kümmell disease.Methods Included for the present retrospective study were 42 patients with Kümmell disease who had been treated by percutaneous kyphoplasty (PKP) or percutaneous vertebroplasty (PVP) at Department of Spine Surgery,Honghui Hospital from October 2016 to June 2018.They were 11 men and 31 women,aged from 43 to 72 years (average,57.4 years).The operation was aided by Iso-C 3D navigational system in 21 patients (observation group) and by X-ray fluoroscopy in the other 21 patients (control group).The 2 groups were compared before operation,one day and 6 months after operation in terms of visual analogue scale (VAS),Oswestry disability index (ODI),cobb angle and anterior vertebral height.Results The 2 groups were comparable because there were no significant differences between them in the preoperative general data (P > 0.05).All the patients were followed up for an average of 9.6 months (from 6.0 to 18.5 months).At one day after operation for the observation andcontrol groups,the VAS scores (2.2 ±0.7 and 3.9 ± 1.5),ODI scores (15.6 ±2.8 and 26.2 ±6.9),cob angles (19.5° ± 1.7° and 20.8° ± 0.8°) and anterior vertebral heights (20.7 ± 1.4 and 18.7 ± 1.5 mm) were all significantly improved compared with those before operation (P < 0.05).At 6 months after operation for the observation and control groups,the VAS scores (1.6±0.6 and 2.7±1.0),ODI (14.2±3.1 and 21.5 ±4.2),cob angles (18.6°± 1.8° and 19.0°± 1.7°) and anterior vertebral heights (19.9 ± 1.8 and 17.8 ± 1.6 mm) were not significantly different from those at one day after operation (P > 0.05).The VAS,ODI,cobb angle and anterior vertebral height at one day after operation for the observation group were all significantly better than those for the control group (P < 0.05).The VAS,ODI and anterior vertebral height at 6 months after operation for the observation group were significantly better than for the control group (P < 0.05),but there was no significant difference between the 2 groups in the cobb angle (P > 0.05).No complications were observed in the observation group but 6 cases in control group reported cement leakage.Conclusion In the PKP/PVP treatment of Kümmell disease,Iso-C 3D navigational system may be superior to traditional X-ray fluoroscopy in that it can lead to better recovery of anterior vertebral height,kyphosis correction,pain relief and quality of life.
9.Correlation between changes of cervical longus and cervical extensor muscles and clinical efficacy after anterior cervical discectomy and fusion
Shuai YANG ; Zhu GUO ; Hongfei XIANG ; Chang LIU ; Youfu ZHU ; Zhaoyang GUO ; Guoqing ZHANG ; Xiaolin WU ; Yan WANG ; Bohua CHEN
Chinese Journal of Orthopaedics 2022;42(2):111-120
Objective:To evaluate the volume changes of cervical longus and cervical extensor after anterior cervical discectomy and fusion (ACDF), and the correlation with the clinical efficacy of patients.Methods:All of 57 patients with cervical spondylotic myelopathy who underwent single-segment ACDF surgery from January 2013 to December 2018 were analyzed. The follow-up time was 23.0±4.8 months (range 16-34 months). All included subjects underwent MR examination within 1 week before operation and 3rd, 12th months after operation and at the last follow-up. The axial section cross section area (AxCSA) of the cervical longus and the ratio of length to short diameter line (RLS) at the level of each disc of C 2-C 7 were measured on the axial T2WI. Calculate the volume of the cervical longus based on the layer thickness. At the same time, measure the cervical extensor cross-sectional area (CESA) of the same level including the multifidus, cervical semispinous muscle, semispinous head, splinter head, and cervical splinter muscles, and compare CESA with the corresponding vertebral cross-sectional area (VBA). The ratio is analyzed as the volume of the neck extensor muscle, namely CESA/VBA. At the 3rd and 12th months after operation and at the last follow-up, the axial pain was assessed by visual analogue scale (VAS) for assessing pain, and the modified Japanese Orthopedic Association score (mJOA) and the neck dysfunction index (NDI) were used to assess the functional status of the cervical spine. Analyze the morphological changes of thecervical longus and extensor cervical muscles before and after the operation and during the follow-up period, and analyze the correlation with VAS, mJOA, and NDI. Results:Compared with the preoperative period, the average AxCSA of the surgical segment decreased at the 3rd and 12th months after the operation and at the last follow-up. The difference was statistically significant ( F=24.113, P<0.05), which was changed from 140.84±19.51 mm 2 respectively reduce to 117.74±17.15 mm 2 ( t=6.714, P<0.05), 116.37±18.67 mm 2 ( t=6.841, P<0.05) and 116.27±18.65 mm 2 ( t=6.873, P<0.05). Compared with preoperatively, they were reduced by 16.40%, 17.37% and 17.45%, respectively, while the average RLS of surgical segments increased slightly, and the difference was statistically significant ( F=22.612, P<0.05), which increased from preoperative 1.97±0.67 to 2.73±0.60 (38.58% increased, t=6.380, P<0.05), 2.82±0.64 (43.15% increased, t=6.926, P<0.05) and 2.74±0.62 (39.09% increased, t=6.368, P<0.05). The volume of thecervical longus of the patients decreased after the operation, and the difference was statistically significant ( F=64.511, P<0.05), which decreased from 8853.48±458.65 mm 3 before the operation to 7834.53±461.59 mm 3 (11.51% decreased, t=11.822, P<0.05), 7926.42±456.24 mm 3 (10.47% decreased, t=10.819, P<0.05), 7892.38±450.78 mm 3 (10.86% decreased, t=11.283, P<0.05). There were no statistically significant differences in the non-surgical segment AxCSA, RLS and the volume of thecervical longus at the 3rd and 12th months after surgery and the last follow-up ( P>0.05). There was no statistically significant difference of CESA and CESA/VBA compared to preoperative in the surgical segment and non-surgical segment ( P>0.05). Pearson correlation analysis showed that the volume of cervical longus and VAS at the 3rd month ( r=-0.308, P<0.05), the 12th month ( r=-0.210, P<0.05) and the last follow-up ( r=-0.404, P<0.05) were negatively correlated; Among the volume of cervical longus and NDI in the 3rd month ( r=-0.511, P<0.05), 12th month ( r=-0.518, P<0.05) and the last follow-up ( r=-0.352, P<0.05), there was a negative correlation; However, there was no statistically significant correlation between the cervical longus muscle volume and mJOA at each follow-up time point ( P>0.05); There was no significant correlation between CESA/VBA and VAS, NDI, and mJOA at the 3rd, 12th and last follow-up ( P>0.05). Conclusion:The volume and morphology of cervical longus after ACDF was significantly reduced compared with that before the operation, but the volume and morphology of the cervical extensor muscle did not change significantly. ACDF surgery mainly affects the cervical longus corresponding to the surgical segment, and the volume is negatively correlated with the VAS and NDI during follow-up.
10.Studies on the differentiation of human urine derived stem cells into nucleus pulposus-like cells induced by human nucleus pulposus cell exosomes
Baoxin SHANG ; Zhu GUO ; Hongfei XIANG ; Yan WANG ; Jianwei GUO ; Zhaoyang GUO ; Youfu ZHU ; Wenbo WU ; Bohua CHEN ; Guoqing ZHANG
Chinese Journal of Orthopaedics 2022;42(13):847-855
Objective:To investigate the effects of exosomes of human nucleus pulposus cells (NPCs) on the differentiation of urine derived stem cells (USCs) into nucleus pulposus-like cells.Methods:USCs and NPCs were isolated and cultured in vitro. The exosomes of NPCs were extracted and detected by Western-blot. USCs cytoplasm was transfected with GFP lentivirus, while nucleus was transfected with DAPI dye. The NPCs exosomes were transfected with PKH26 dye. After co-incubation for 12 h, USCs and NPCs exosomes were observed by macroscopy. USCs differentiation was induced by NPCs exosomes and non-contact co-culture methods. The relative expression of marker gene mRNA of nucleus pulposus cells in each group and the absorbance at 450 nm wavelength were detected.Results:The isolated USCs had the ability to differentiate into osteocytes, adipocytes and chondrocytes with high expression of marker CD29 (99.57%), CD44 (97.46%) and CD73 (97.71%) and with low expression of negative proteins CD31 (0.59%) and CD45 (0.19%). The isolated NPCs highly expressed nuclear pulposus cell marker COL2A1, ACAN and SOX-9. The exosomes extracted from NPCs showed high expression of exosome marker CD63, CD81 and Tsg101. After 12 h co-incubation, NPCs exosomes fused with USCs membrane and appeared in the cytoplasm of USCs. At 3, 5 and 7 days of co-culture, the absorbance value of USCs cells in exosome group (0.44±0.004, 0.76±0.004, 0.82±0.006) was higher than that in co-culture group (0.39±0.022, 0.63±0.035, 0.69±0.012) ( P<0.05). The mRNA relative expression of USCs nucleus pulposus marker genes ACAN (1.80±0.31, 3.50±0.21, 5.35±0.31, 7.46±0.12), COL2A1 (1.43±0.15, 4.33±0.23, 6.89±0.22, 8.11±0.31), SOX-9 (2.21±0.13, 3.13±0.11, 3.96± 0.14, 4.52±0.26) and HIF-1α (1.45±0.16, 2.14±0.21, 4.31±0.41, 4.01±0.25) in exosomes group were significantly higher than those in the control group ( P<0.05) at the 3rd, 7th, 14th and 21st days. The mRNA relative expression of USCs nucleus pulposus marker genes ACAN (5.69±0.21, 6.69±0.13), COL2A1 (6.33±0.17, 7.89±0.15), SOX-9 (4.19±0.29, 4.38±0.12), HIF-1α (4.49±0.32, 4.96±0.26) in exosomes group were significantly higher than those ACAN (3.69±0.35, 5.13±0.23), COL2A1 (3.40±0.16, 6.79±0.19), SOX-9 (2.26±0.32, 3.69±0.26), HIF-1α (2.39±0.11, 3.96±0.13) in non-contact co-culture group ( P<0.05) at the 14th and 21st days. Conclusion:Human nucleus pulposus exosomes could induce differentiation of human USCs into nucleus pulposus-like cells in vitro. Compared with non-contact co-culture, exosomes have higher induction efficiency and can better maintain the proliferation activity of nucleus pulposus-like cells