Human Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Attenuate Blood-Spinal Cord Barrier Disruption via the TIMP2/MMP Pathway After Acute Spinal Cord Injury.

After spinal cord injury (SCI), destruction of the blood-spinal cord barrier (BSCB) results in infiltration of blood cells, such as neutrophils and macrophages, leading to permanent neurological dysfunction. Previous studies have shown that human bone marrow mesenchymal stem cell (BMSC)-derived exosomes have a beneficial neuroprotective effect in SCI models. However, whether BMSC-Exos contribute to the integrity of the BSCB has not been clarified. The purpose of this study was to investigate the mechanism of BMSC-Exo-induced changes in the permeability of the BSCB after SCI. Here, we first used BMSC-Exos to treat an SCI rat model, showing that BMSC-Exos can inhibit BSCB permeability damage and improve spontaneous repair. Next, we found that tissue inhibitors of matrix metalloproteinase 2 (TIMP2) have been shown to play an important role in the function of BMSC-Exos by inhibiting the matrix metalloproteinase (MMP) pathway, thereby reducing the reduction of cell junction proteins. Therefore, we constructed siTIMP2 to knock out TIMP2 in BMSC-Exos, which caused the activity of BMSC-Exos to be significantly weakened. Finally, we constructed an in vitro model of BSCB with HBMECs and verified that TIMP2 in BMSC-Exos in vitro can also alleviate BSCB damage. This proof-of-principle study demonstrates that BMSC-Exos can preserve the integrity of the BSCB and improve functional recovery after SCI through the TIMP2/MMP signaling pathway.

One stage posterior pedicle screw fixation combined with transpedicle intervertebrae titanic mesh autograft for type C thoracolumbar fractures / 中华创伤杂志

Objective To evaluate the therapeutic effeet of one stage posterior pedicle screw fixation combined with transpedicle intervertebrae titanic mesh autograft versus traditional posterior and anterior approach surgery in the treatment of severe thoracolumbar fractures.Methods A retrospective case-control study was done on 40 cases of type C thoracolumbar fractures admitted from January 2012 to December 2015.There were 28 males and 12 females,with age range of 20-48 years (mean,30.6 years).The fractures were located at T11 in 4 cases,at T12 in 16,at L1 in 14,and at L2 in 6.All cases were divided into two groups (with 20 cases per group) according to treatment method difference.The cases in posterior group had one stage posterior pedicle screw fixation combined with transpedicle intervertebrae titanic mesh autograft,and the others in posterior and anterior group were treated by traditional posterior and anterior approach surgery.The operation duration,volume of blood loss,hospital stay,kyphosis correction rate,visual analogue scale (VAS) and Oswestry disability index (ODI) were compared between the two groups.Results All patients were followed up for 10-46 months (mean,28.6 months).In posterior group,the average operation time was 154 minutes,the average blood loss was 564 ml,the postoperative suction drainage was 180.5 ml,the time period between surgery and recovery of walking ability was 5.9 days,and the hospital stay was 10.6 days.While in posterior and anterior group,the average operation time was 248.5 minutes,with the average blood loss of 960.8 ml,the postoperative suction drainage of 359.2 ml,the time duration between surgery and recovery of walking ability of 8.4 days,and the hospital stay of 14.5 days (P ＜ 0.05).At one week and six months postoperatively,the height ratio of anterior edge,Cobb angle,VAS and ODI in both groups were improved compared to the preoperative status (P ＜ 0.05).But there was no significant difference of these indicators between two groups (P ＞ 0.05) except for lumbar back pain one week after operation (P ＞ 0.05).Conclusions Through single pathway of posterior approach,one stage posterior pedicle screw fixation combined with transpedicle intervertebrae titanic mesh autograft can complete reduction of fractured vertebral body,spinal cord decompression,and anterior-middle column stability reconstruction.Compared with traditional combined posterior and anterior approach surgery,this technique has many advantages including simpler manipulation,less invasion,shorter rehabilitation time and equal bony fusion and hence is an ideal option for type C thoracolumbar fractures.

Unilateral atlantoaxial pedicle screw fixation plus structural iliac bone graft for treatment of unstable atlas fractures / 中华创伤杂志

Objective To evaluate the efficacy of unilateral atlanto-axial transpedicle screw fixation plus iliac bone graft for treatment of unstable atlas fractures combined with unilateral pedicle dysplasia or comminuted fractures.Methods A retrospective case control study was made on 44 patients with unstable atlas fractures surgically treated between January 2012 to June 2016.Unilateral atlanto-axial transpedicle screw fixation combined with iliac bone graft was performed for 22 patients combined with unilateral pedicle dysplasia or comminuted fractures in Group A[15 males,seven females;(37.5 ± 13.4)years],and bilateral atlanto-axial transpedicle screw fixation combined with iliac bone graft was performed for 22 patients without unilateral pedicle dysplasia or comminuted fractures in Group B [14 males,eight females;(38.1 ± 13.3)years].Between-group differences were compared concerning operation time,intraoperative blood loss,length of hospital stay,success rate of screw placement,postoperative atlantoaxial stability,surgery-related complications,visual analog scale (VAS),Japanese orthopedic association score (JOA) and bone fusion.Results Mean duration of follow-up was 28.4 months (range,14-48 months).In Group A,operation time was (123.4 ± 18.2) min,blood loss was (218.5 ± 80.2) ml,hospital stay was (7.1 ± 1.0)d,success rate of screw placement was 100％,postoperative atlanto-axial stability of all patients was obtained,and no complications occurred.In Group B,operation time was (173.4 ± 12.4) min,blood loss was (318.2 ± 61.7) ml,hospital stay was (7.2 ± 0.8) d,success rate of screw placement was 100％,postoperative atlanto-axial stability of all patients was obtained,and no complications occurred.There were significant differences in operation time and blood loss between the two groups (P ＜0.01),while not in hospital stay,success rate,postoperative atlant-oaxial stability,complication incidence,VAS and JOA (P ＞ 0.05).Conclusion Both treatments are effective,but unilateral atlanto-axial transpedicle screw fixation combined with iliac bone graft is associated with relatively shorter operation time and less blood loss and hence is considered as a better choice for treatment of unstable atlas fractures.