Duraplasty of PHBV/PLA/Col membranes promotes axonal regeneration by inhibiting NLRP3 complex and M1 macrophage polarization in rats with spinal cord injury.

Duraplasty after decompression decreases the lesion size and scar formation, promoting better functional recovery, but the underlying mechanism has not been clarified. Here, we fabricated a series of poly(hydroxybutyrate-co-hydroxyvalerate)/polylactic acid/collagen (PHBV/PLA/Col) membranes and cultured them with VSC4.1 motor neurons. The material characteristics and in vitro biological characteristics were evaluated. In the subcutaneous implantation test, PHBV/PLA/COl scaffolds supported the cellular infiltration, microvasculature formation, and decreased CD86-positive macrophage aggregation. Following contusion spinal cord injury at T10 in Sprague-Dawley rats, durotomy was performed with allograft dura mater or PHBV/PLA or PHBV/PLA/Col membranes. At 3 days post-injury, Western blot assay showed decreased the expression of the NLRP3, ASC, cleaved-caspase-1, IL-1ß, TNF-α, and CD86 expression but increased the expression of CD206. Immunofluorescence demonstrated that duraplasty with PHBV/PLA/Col membranes reduced the infiltration of CD86-positive macrophages in the lesion site, decreased the glial fibrillary acidic protein expression, and increased the expression of NF-200. Moreover, duraplasty with PHBV/PLA/Col membranes improved locomotor functional recovery at 8 weeks post-injury. Thus, duraplasty with PHBV/PLA/Col membranes decreased the glial scar formation and promoted axon growth by inhibiting inflammasome activation and modulating macrophage polarization in acute spinal cord injury.

Scar Tissue-Targeting Polymer Micelle for Spinal Cord Injury Treatment.

Spinal cord injury (SCI) is a devastating disorder, leading to permanent motor and sensory deficit. Despite recent advances in neurosciences, the treatment efficacy on SCI patients remains unsatisfactory, mainly due to the poor accumulation, short retention, and lack of controlled release of therapeutics in lesion tissue. Herein, an injured spinal cord targeting prodrug polymer micelle is built. An esterase-responsive bond is used to link apocynin (APO) monomer, because of the enhanced esterase activity found in microglia cells after activation, which ensures a controlled degradation of APO prodrug (Allyloxypolyethyleneglycol-b-poly [2-(((4-acetyl-2-methoxyphenoxy)carbonyl)oxy)ethyl methacrylate], APEG-PAPO or PAPO) by activated microglia cells. A scar tissue-homing peptide (cysteine-alanine-glutamine-lysine, CAQK) is introduced to the PAPO to endow the polymer micelle the lesion tissue-targeting ability. As a result, this CAQK-modified prodrug micelle (cPAM) exhibits an improved accumulation and prolonged retention in lesion tissue compared to the control micelle. The cPAM also leads to superior tissue protection and sustained motor function recovery than the control groups in a mouse model of SCI. In conclusion, the cPAM induces an effective treatment of SCI by the lesion tissue specific delivery of the prodrug polymer via its robust scar binding effect, making the scar tissue a drug releasing platform for sustained treatment of SCI.

An injectable recombinant human milk fat globule-epidermal growth factor 8-loaded copolymer system for spinal cord injury reduces inflammation through NF-κB and neuronal cell death.

Spinal cord injury (SCI) is a common disease and a major cause of paralysis, carrying much burden around the world. Despite the progress made with growth factors therapy, the response rate of acute SCI treatment still remains unsatisfactory, due largely to complex and severe inflammatory reactions. Herein, we prepare a MFG-E8-loaded copolymer system-based anti-inflammation therapy for SCI treatment. It is shown that the MFG-E8-loaded copolymer system can decrease pro-inflammatory cytokine expression and neuron death. In a rat model of crush-caused SCI, the copolymer system shows significant therapeutic efficacy by ameliorating inflammation, decreasing fibrotic scar, promoting myelin regeneration and suppressing overall SCI severity.

Motion preservation in type II odontoid fractures using temporary pedicle screw fixation: a preliminary study.

PURPOSE: To assess the feasibility of temporary pedicle screw fixation for motion preservation of type II odontoid fractures unsuitable for anterior screw. METHODS: Between 2012 and 2013, temporary pedicle screw fixation was performed in 13 patients with type II odontoid fractures unsuitable for anterior screw. The patients were 10 men and 3 women with an average age of 40. The implant was removed after fracture union. Dynamic CT was performed ≥ 1 month after implant removal to evaluate atlantoaxial rotation and axial neck rotation. Literature data on axial neck rotation were obtained as a historical control. RESULTS: Fifty-two pedicle screws were placed successfully with satisfactory fracture reduction achieved in all patients. The average follow-up period was 14.2 months. At a mean of 9 months after the initial operation, fracture union was confirmed and implants were removed. The average total axial neck rotation was 116.5° ± 25.8° (78.2 ± 14.8 % of the historical controls). The average total atlantoaxial rotation was 34.2° ± 22.0° (27.3 ± 13.8 % of total axial neck rotation). CONCLUSIONS: Temporary pedicle screw fixation is a feasible technique for motion preservation of type II odontoid fractures unsuitable for anterior screw.

Swelling-Mediated Mechanical Stimulation Regulates Differentiation of Adipose-Derived Mesenchymal Stem Cells for Intervertebral Disc Repair Using Injectable UCST Microgels.

Mechanical stimulation is an effective approach for controlling stem cell differentiation in tissue engineering. However, its realization in in vivo tissue repair remains challenging since this type of stimulation can hardly be applied to injectable seeding systems. Here, it is presented that swelling of injectable microgels can be transformed to in situ mechanical stimulation via stretching the cells adhered on their surface. Poly(acrylamide-co-acrylic acid) microgels with the upper critical solution temperature property are fabricated using inverse emulsion polymerization and further coated with polydopamine to increase cell adhesion. Adipose-derived mesenchymal stem cells (ADSCs) adhered on the microgels can be omnidirectionally stretched along with the responsive swelling of the microgels, which upregulate TRPV4 and Piezo1 channel proteins and enhance nucleus pulposus (NP)-like differentiation of ADSCs. In vivo experiments reveal that the disc height and extracellular matrix content of NP are promoted after the implantation with the microgels. The findings indicate that swelling-induced mechanical stimulation has great potential for regulating stem cell differentiation during intervertebral disc repair.

Sustained release of GDF5 from a designed coacervate attenuates disc degeneration in a rat model.

Low back pain is often caused by intervertebral disc degeneration, which is characterized by nucleus pulposus (NP) and extracellular matrix (ECM) degeneration. Human adipose-derived stem cells (hADSCs) induced by growth and differentiation factor-5 (GDF5) can differentiate into an NP-like phenotype. Although stem cell-based therapy with prolonged exposure to growth factors is regarded as a promising treatment, the efficacy of this approach in attenuating the disc degeneration process is limited by the short lifespan of growth factors. In our study, a unique growth factor delivery vehicle composed of heparin and the synthetic polycation poly(ethylene argininylaspartate diglyceride) (PEAD) was used to sustain GDF5 release. The results showed that sustained release of GDF5 by the PEAD:heparin delivery system promoted hADSC differentiation to an NP-like phenotype in vitro. After injection of the PEAD:heparin:GDF5 delivery platform and hADSCs into intervertebral spaces of coccygeal (Co) vertebrae Co7/Co8 and Co8/Co9 of the rat, the disc height, water content, and structure of the NPs decreased more slowly than other treatment groups. This new strategy may be used as an alternative treatment for attenuating intervertebral disc degeneration with hADSCs without the need for gene therapy. STATEMENT OF SIGNIFICANCE: Low back pain is often caused by intervertebral disc degeneration, which is characterized by nucleus pulposus (NP) and extracellular matrix (ECM) degeneration. Human adipose-derived stem cells (hADSCs) induced by growth and differentiation factor-5 (GDF-5) can differentiate into an NP-like phenotype. Although stem cell-based therapy with prolonged exposure to growth factor is regarded as a promising treatment, the efficacy of this approach in the disc regeneration process is limited by the short life of growth factors. In our study, a unique growth factor delivery vehicle comprised of heparin and the synthetic polycation poly(ethylene argininylaspartate diglyceride) (PEAD) was used to sustain the release of GDF-5. Numerous groups have explored IDD regeneration methods in vitro and in vivo. Our study differs in that GDF5 was incorporated into a vehicle through charge attraction and exhibited a sustained release profile. Moreover, GDF-5 seeded coacervate combined with hADSC injection could be a minimally invasive approach for tissue engineering that is suitable for clinical application. We investigated the stimulatory effects of our GDF-5 seeded coacervate on the differentiation of ADSCs in vitro and the reparative effect of the delivery system on degenerated NP in vivo.

PHBV/PLA/Col-Based Nanofibrous Scaffolds Promote Recovery of Locomotor Function by Decreasing Reactive Astrogliosis in a Hemisection Spinal Cord Injury Rat Model.

OBJECTIVES: Biomaterials are used to aid in the regeneration of damaged tissue and in promotion of axonal guidance following spinal cord injury (SCI). In the present study, electrospun composite poly(hydroxybutyrate-cohydroxyvalerate) (PHBV), poly(lactic acid) (PLA), and collagen (Col) nanofibrous scaffolds were applied to determine their roles in neural regeneration and recovery in a rat model of SCI. METHODS: The morphological and chemical properties of the electrospun scaffolds were investigated. The growth and proliferation of astrocytes on the scaffolds were assessed by MTT assay. The differentiation and gene expression of astrocytes on the scaffolds were measured by immunofluorescence and quantitative real-time polymerase chain reaction (q-PCR) assays. In a rat spinal cord hemisection model with 3-mm defects, 80 Sprague-Dawley rats were randomly divided into five groups: Sham group, SCI group, SCI+PHBV/PLA group, SCI+PHBV/PLA/Col (70:30) group, and SCI+PHBV/PLA/Col (50:50) group. The Basso-Beattie-Bresnahan (BBB) scores were evaluated every week postsurgery, and (immuno) histological and protein analyses were performed on specimens at 8 weeks. RESULTS: PHBV/PLA/Col scaffolds strongly inhibited the activation of astrocytes without decreasing their proliferation. qPCR assays revealed significant increases in the expression of brain lipid-binding protein (BLBP), glutamate transporter 1 (GLT-1) and S100 calcium-binding protein B (S100-ß), but decreases in the expression of glial fibrillary acidic protein (GFAP), chondroitin sulphate sulfate proteoglycan (CSPG), neurocan, and phosphacan in the PHBV/PLA/Col scaffold group. In a series of in vivo experiments, PHBV/PLA/Col scaffold-treated SCI groups showed significant reductions in the numbers of CD68- and GFAP-immunopositive astrocytes within the interface of the remodeled tissue layer, but increased expression of NF-200 in residual neurons with better locomotor functional recovery. However, there were no significant differences between the PHBV/PLA/Col (70:30) and PHBV/PLA/Col (50:50) groups, except in BBB scores. CONCLUSIONS: PHBV/PLA/Col nanofibrous scaffolds were biocompatible and significantly promoted astrocyte differentiation but decreased astrocyte activation. The topographic structures of the PHBV/PLA/Col (70:30 and 50:50) nanofibers were favorable for neural regeneration due to a decrease in astrogliosis in SCI rats.

Posterior arthrodesis of C1-C3 for the stabilization of multiple unstable upper cervical fractures with spinal cord compromise: A case report and literature review.

BACKGROUND: Multiple fractures of the atlas and axis are rare. The management of multiple fragment axis fractures and unstable atlas fractures is still challenging for the spinal surgeon. There are no published reports of similar fractures with 3-part fracture of axis associated with an unstable atlas fracture. CASE SUMMARY: We present a patient with concurrent axis and atlas fractures, which have not been reported. The patient suffered hyperextension injury with neck pain and numbness of the bilateral upper extremity associated with weakness after a 2-m fall. The axis fractures included an odontoid type IIA fracture and traumatic spondylolisthesis of C2-C3. The atlas fracture was unstable. The neurological examination manifested as central canal syndrome, which was due to the hyperextension injury of cervical spine and spondylolisthesis of C2-C3. The patient was diagnosed as multiple unstable upper cervical fractures with spinal cord compromise. We performed posterior arthrodesis of C1-C3. Postoperatively, the patient showed neurological improvement, and C1-C3 had fused at the 3-month follow-up. CONCLUSION: Posterior arthrodesis of C1-C3 could provide a stable fixation for the 3 parts of axis (an odontoid type IIA fracture and traumatic spondylolisthesis of C2-C3) combined an unstable atlas fracture. Both the patient and the doctor were satisfied with the results of the treatment. So posterior arthrodesis of C1-C3 is a suitable treatment option for the treatment of a concurrent unstable atlas fracture and multiple fractures of the axis.

[Diagnosis and treatment of odontoid fracture combined with lower cervical spinal injury].

OBJECTIVE: To investigate the mechanism, clinical features and treatment of odontoid fracture combined with lower cervical spinal injury. METHODS: From January 1999 to December 2004, 57 cases of type II or shallow type III odontoid fractures were studied retrospectively. Six cases were found combined with lower cervical injury, the mean age was 54 years, and 4 of the 6 cases were complicated with cervical spondylarthrosis or ankylosing spondylitis. For the lower cervical injury, fracture-dislocation was found in 2 cases, the disruption of disc and ligament was found in 4 cases among which 2 cases were suffered from incomplete spinal cord injury; Both were caused by lower cervical spinal injury. All of the 6 cases were performed with surgery in odontoid fracture and lower cervical spinal injury simultaneously; Lower cervical spinal injuries were stabilized firstly in 2 cases, which responsible for neurological involvement; For the other 4 cases without neurological involvement, stabilization was performed in odontoid fracture firstly in 2 cases, due to inability to achieve reduction of odontoid fracture preoperatively, however, for the another 2 cases with anatomic reduction of the odontoid fracture preoperatively, lower cervical injuries were stabilized firstly. RESULTS: After an average follow-up of 10 months, all cases were obtained solid fusion both in odontoid fracture and lower cervical spinal injury, and without the complications associated with operation and prolonged bed rest. Two cases with neurological defect improved 1 scale in Frankel score. CONCLUSIONS: The incidence of odontoid fracture combined with lower cervical spinal injury is about 10.5% of the odontoid fracture, and it is vulnerable in the elderly patient with cervical spondylarthrosis. MRI should be used routinely for accurate diagnosis. Surgical stabilization is the choice of treatment due to facilitating early rehabilitation and reducing the complications. The surgical schedule is planned according to the fact of neurological involvement and the extent of stability between the odontoid fracture and lower cervical spinal injury.

[Clinical effect of posterior atlanto axial vertebra internal fixation for treatment of instability of occipitocervical].

OBJECTIVE: To explore radiographic results and clinical effects of posterior atlanto axial vertebra internal fixation in treating instability of occipitocervical. METHODS: The clinical data of 155 patients with instability of occipitocervical treated by posterior atlanto axial vertebra internal fixation were respectively analyzed from September 2005 to January 2011. There were 68 males and 87 females, ranging in age from 6 to 75 years old with an average of 45.6 years old. Of them, 53 cases were fresh odontoid fractures(Aderson type II C), 30 cases were os odontoideum, 20 cases were old odontoid fractures, 18 cases were unstable atlas fractures, 12 cases were atlanto axial rotatory dislocation, 11 cases were atlanto axial dislocation after rheumatoid arthritis, and 11 cases were basilar invagination. Radiographic results were evaluated in terms of atlas pedicle screw fixation, bone healing and bone graft fusion. Clinical effect evaluation included relief of pain in the occipital-cervical region by VAS score and JOA score. RESULTS: Totally 300 screws were set through atlas pedicle screw fixation in 150 patients. Five patients receivde hook fixation. Postoperative CT showed ideal nailing were 275 (91.7%),acceptable nailing were 14 (4.7%) and unacceptable nailing were 11 (3.6%). All patients were followed up, and the duration ranged from 16 to 40 months with an average of 25.4 months. The fresh fractures healed and 140 cases got bone graft fusion. Preoperative VAS and JOA score were respectively improved from (7.2 +/- 1.1), (7.3 +/- 2.4) to (3.2 +/- 1.1), (13.3 +/- 2.4) at the latest follow-up. CONCLUSION: Posterior atlanto axial vertebra internal fixation in treating instability of occipitocervical can effectively recover physiological curvature of cervical, provide mechanical stability, and obtain good clinical effect. For the young patients who require further activity, posterior fixation and non-fusion technology is a good choose, which can avoid bone graft.

Dual release of dexamethasone and TGF-ß3 from polymeric microspheres for stem cell matrix accumulation in a rat disc degeneration model.

Low back pain is frequently caused by nucleus pulposus (NP) degeneration. Tissue engineering is a powerful therapeutic strategy which could restore the normal biomechanical motion of the human spine. Previously we reported that a new nanostructured three-dimensional poly(lactide-co-glycolide) (PLGA) microsphere, which is loaded with dexamethasone and growth factor embedded heparin/poly(l-lysine) nanoparticles via a layer-by-layer system, was an effective cell carrier in vitro for NP tissue engineering. This study aimed to investigate whether the implantation of adipose-derived stem cell (ADSC)-seeded PLGA microspheres into the rat intervertebral disc could regenerate the degenerated disc. Changes in disc height by plain radiograph, T2-weighted signal intensity in magnetic resonance imaging (MRI), histology, immunohistochemistry and matrix-associated gene expression were evaluated in normal controls (NCs) (without operations), a degeneration control (DC) group (with needle puncture, injected only with Dulbecco's modified Eagle's medium), a PLGA microspheres (PMs) treatment group (with needle puncture, PLGA microspheres only injection), and PLGA microspheres loaded with ADSCs treatment (PMA) group (with needle puncture, PLGA microspheres loaded with ADSC injection) for a 24-week period. The results showed that at 24 weeks post-transplantation, the PM and PMA groups regained disc height values of ∼63% and 76% and MRI signal intensities of ∼47% and 76%, respectively, compared to the NC group. Biochemistry, immunohistochemistry and gene expression analysis also indicated the restoration of proteoglycan accumulation in the discs of the PM and PMA groups. However, there was almost no restoration of proteoglycan accumulation in the discs of the DC group compared with the PM and PMA groups. Taken together, these data suggest that ADSC-seeded PLGA microspheres could partly regenerate the degenerated disc in vivo after implantation into the rat degenerative intervertebral disc.

Fabrication of a Layered Microstructured Polymeric Microspheres as a Cell Carrier for Nucleus Pulposus Regeneration.

This study aimed to investigate the feasibility of nanostructured 3D poly(lactide-co-glycolide) (PLGA) constructs, which are loaded with dexamethasone (DEX) and growth factor embedded hepaiin/poly(L-lysine) nanoparticles by a layer-by-layer system, to serve as an effective scaffold for nucleus pulposus (NP) tissue engineering. Our results demonstrated that the microsphere constructs were capable of simultaneously releasing basic fibroblast growth factor and DEX with approximately zero-order kinetics. The dual bead microspheres showed no cytotoxicity, and promoted the proliferation of the rat mesenchymal stem cells (rMSCs) by lactate dehydrogenase assay and CCK-8 assay. After 4 weeks of culture in vitro, the rMSCs- scaffold hybrids contained significantly higher levels of sulfated GAG/DNA and type-II collagen than the control samples. Moreover, quantity real-time PCR analysis revealed that the expression of disc-matrix proteins, including type-II collagen, aggrecan and versican, in the rMSCs-scaffold hybrids was significantly higher than the control group, whereas the expression of osteogenic differentiation marker type-I collagen was decreased. Taken together, these data indicate that the heparin bound bFGF-coated and DEX-loaded PLGA microsphere constructs is an effective bioactive scaffold for the regeneration of NP tissue.

The treatment of concomitant odontoid fracture and lower cervical spine injuries.

STUDY DESIGN: A retrospective study. OBJECTIVE: To investigate the treatment of odontoid fractures combined with lower cervical spinal injury. SUMMARY OF BACKGROUND DATA: Odontoid fractures combined with a lower cervical spinal injury are rarely reported in the literature and their incidence and characteristics are not well known. METHODS: Seventy-six patients with type II shallow type III odontoid fractures were studied retrospectively. Nine odontoid fractures were found combined with lower cervical spinal injuries; the mean age of patients was 56.8 years. For lower cervical spinal injuries, dislocation was found in 4 patients and disruption of the disc and ligament was found in 5 patients. All patients received surgical management for the odontoid fracture and lower cervical spinal injury in the same operative session. Surgical priority was decided based on neurologic complications, segmental instability, and reducibility of the luxated lower cervical spine. For 3 quadriparetic patients, surgical priority was given to their spinal injuries. For the other 6 patients without neurologic deficits, surgical priority was given to the odontoid fractures in 5 patients because of successful reduction of the dislocation or nondislocation in the lower cervical spine; surgical priority was given to an irreducible lower cervical spine dislocation in the remaining patient. RESULTS: After an average follow-up period of 18 months, there were no complications and all patients showed fusion both in the odontoid fracture and the lower cervical spinal injury. Three patients with a neurologic deficit improved by 1 or 2 grades on the ASIA scale. CONCLUSION: In this series, 9 of 76 (12%) of patients with odontoid fractures also had a lower cervical spinal injury. Surgical stabilization was the choice of treatment as it facilitated early rehabilitation and reduced complications. We propose a new algorithm for treatment according to neurologic complications, segmental instability, and reducibility of the luxated lower cervical spine.