Repair of Spinal Cord Injury by Inhibition of PLK4 Expression Through Local Delivery of siRNA-Loaded Nanoparticles.

Polo-like kinase 4 (PLK4) is one of the key regulators of centrosomal replication. However, its role and mechanism in spinal cord injury (SCI) are still unclear. The SCI model on rats was constructed and the expression and localization of PLK4 in the spinal cord are analyzed with Western blot and immunofluorescence, respectively. Then the specific siRNAs were encapsulated in nanoparticles for the inhibition of PLK4 expression. Afterward, the role of PLK4 on astrocytes was investigated by knocking down its expression in the primary astrocytes. Moreover, siRNA-loaded nanoparticles were injected into the injured spinal cord of rats, and the motor function recovery of rats after SCI was assessed using the Basso, Beattie, and Bresnahan (BBB) locomotor scale method. Notably, the siRNA-loaded nanoparticles effectively transfect primary astrocytes and significantly inhibit PLK4 expression, together with the expression of PCNA with significance. After treatment, restoration of the motor function following SCI was significantly improved in the PLK4 knockdown group compared with the control group. Therefore, we speculate that inhibition of Plk4 may inhibit the proliferation of astrocytes and decrease the inflammatory response mediated by astrocytes, so as to promote the functional recovery of SCI. In conclusion, inhibition of PLK4 expression via siRNA-loaded nanoparticles may be a potential treatment for SCI.

[Comparison of clinical outcomes between unilateral fixation fusion and minimally invasive spine transforaminal lumbar interbody fusion in treating lumbar disc herniation].

OBJECTIVE: To compare the short-term clinical outcome between unilateral fixation fusion (ULF) and minimally invasive spine transforaminal lumbar interbody fusion (MIS-TLIF) in treating lumbar disc herniation (LDH). METHODS: The clinical data of 39 patients with LDH were retrospectively analyzed from June 2008 to March 2013. There was 22 males and 17 females, aged from 45 to 75 years old with an average of 56.9 years. Therer were 3 cases in L3,4, 15 cases in L4,5, 21 cases in L5S1. Among them, 21 patients underwent unilateral fixation fusion (ULF group) and 18 underwent minimally invasive spine transforaminal lumbar interbody fusion (MIS-TLIF group). Operation time, blood loss, the times of radiographic exposure and hospital stay were noted and compared between two groups. Radiograph informations were regularily accessed and VAS, ODI scores were recorded at 3 days and 3, 6, 12 months after operation, respectively. According to modified Macnab criteria, the clinical effects were evaluated at final follow-up. RESULTS: All operations were successful without severe complications. The averaged operative time and the times of radiographic exposure in ULF group [(95 ± 25) min and (4.2 ± 0.4) times] were less than that of MIS-TLIF group [(120 ± 35) min and (10.1 ± 3.9) times] (P < 0.05). But, the mean blood loss and hospital stay in MIS-TLIF group [(75 ± 45) ml and (7.2 ± 2.2)d ]were less than that of ULF group [(165 ± 60) ml and (11.0 ± 3.7) d] (P < 0.01). All patients were followed up from 12 to 45 months with an average of 29.5 months. The VAS and ODI score had significantly improved during the follow-up and no significant differences were found between two groups at the same time point (P > 0.05). The postoperative radiographs showed internal fixation position was good. And all patients obtained bone fusion by CT scan at 1 year after operation. There was no significant differences in modified Macnab criteria between two groups at the latest follow-up (P > 0.05). CONCLUSION: Favorable short-term clinical effects can be achieved in suitable LDH patients with ULF or MIS-TLIF surgical procedures.

[Case-control study on treating severe tibial open fractures by amputation and limb salvage].

OBJECTIVE: To compare mid-term clinical outcomes between amputation and limb salvage in treating severe open tibial fractures with type Gustilo III B, III C. METHODS: From July 2007 to June 2010,68 patients with severe open tibial fractures with type Gustilo III B, III C treated by amputation and limb salvage were retrospectively analyzed. In amputation group, there were 26 males and 12 females with an average age of (44.9±16.3) years old; and 21 cases were type Gustilo (III B, 17 cases were Gustilo III C; amputation were performed in accordance with soft tissue injury degree of shank, fracture types and surgical exploration. In limb salvageg group, there were 21 males and 9 females with an average age of (43.5±14.7) years old; and 23 cases were type Gustilo III B, 7 cases were Gustilo III C; the method of internal fixation and and wound healing were performed in accordance with patients's specific condition. Operative time, blood loss, hospital stay and postoperative infection was compared between two groups; time of loading and rate of return to work was compared; VAS scoring was used to evaluate condition of pain; SF-36 health queationaire was used to assess postoperative life quality. RESULTS: Totally 60 patients were followed up (33 cases in amputation group and 27 cases in limb salvage group) with an average time of 49.1 months. Operative time, blood loss, hospital stay and postoperative infection in amputation and limb salvage group respectively was (109.0±25.7) min, (245.0±58.6) min; (168.0±49.0) ml, (311.0±137.0) ml; (13.8±2.7) d, (28.8±13.1) d; 7.9%, 36.7%. At the final following-up, there was no significance meaning between two groups in VAS scoring and rate of return to work, but time of loading in amputation group was shorter than that of in limb salvage group. Physiological function in amputation group was better than limb salvage group, while body pain was worse; and there was no signicance meaning in psychological health between two groups. CONCLUSION: Amputation and limb salvage both can treat severe open tibial fractures, and mid-term clinical outcomes between two groups has equivalent efficacy.

Biomechanical evaluation of vertebroplasty using calcium sulfate cement for thoracolumbar burst fractures.

OBJECTIVE: To evaluate the biomechanical performance of vertebroplasty using calcium sulfate cement for thoracolumbar burst fractures. METHODS: Sixteen bovine thoracolumbar spines (T11-L1) were divided into 4 groups (A,B,C and D). After burst-fracture model was created, 12 vertebral bodies in Groups A, B and C were augmented with calcium sulfate cement (CSC), calcium phosphate cement (CPC) and polymethylmethacrylate (PMMA) bone cement, respectively. Each anterior vertebral body height was measured with a caliper at 4 time points: intact conditions (HInt), post-fracture (HFr), post-reduction (HRe) and post-vertebroplasty (HVP). The filling volume of 3 different bone cements was also measured. Each vertebral body was compressed at 0.5 mm/s using a hinged plating system on a materials testing machine to 50% of the post-vertebroplasty height to determine strength and stiffness. Difference was checked using t test or One-way ANOVA. RESULTS: The average strike energy was 66.2 J. Vertebroplasty with different cements could sustain vertebral height. The average filling volume of bone cement in 3 groups was 4.35 ml (CSC), 3.72 ml (CPC) and 3.95 ml (PMMA), respectively, and there was no statistically significant difference among them (P larger than 0.05). Vertebroplasty with PMMA completely restored strength (116%) and stiffness (105%). CSC or CPC partly recovered vertebral strength and stiffness. However, greater strength restoration was got with CSC (1659 N) as compared with CPC (1011N, P less than 0.01). Regarding stiffness, differences between CSC (140 N/mm+/-40 N/mm)and the other two bone cements (CPC:148 N/mm+/-33 N/mm, PMMA:236 N/mm+/-97 N/mm) were not significant (P larger than 0.05). CONCLUSIONS: For a burst-fracture of calf spine, use of CSC for vertebroplasty yields similar vertebral stiffness as compared with PMMA or CPC. Although augmentation with CSC partly obtains the normal strength, this treatment still can be applied in thoracolumbar burst fractures with other instrumental devices in light of its bioactivation.