Biomimetic angle-ply multi-lamellar scaffold for annulus fibrosus tissue engineering.

Constructing a biomimetic scaffold that replicates the complex architecture of intervertebral disc annulus fibrosus (AF) remains a major goal in AF tissue engineering. In this study, a biomimetic angle-ply multi-lamellar polycaprolactone/silk fibroin (PCL/SF) AF scaffold was fabricated. Wet-spinning was used to obtain aligned PCL/SF microfiber sheets, and these were excised into strips with microfibers aligned at +30° or -30° relative to the strip long axis. This was followed by stacking two strips with opposing fiber alignment and wrapping them concentrically around a mandrel. Our results demonstrated that the scaffold possessed spatial structure and mechanical properties comparable to natural AF. The scaffold supported rabbit AF cells adhesion, proliferation, infiltration and guided oriented growth and extracellular matrix deposition. In conclusion, our angle-ply multi-lamellar scaffold offers a potential solution for AF replacement therapy and warrants further attention in future investigations.

Posterior short-segment instrumentation and limited segmental decompression supplemented with vertebroplasty with calcium sulphate and intermediate screws for thoracolumbar burst fractures.

PURPOSE: Thoracolumbar burst fractures treated with short-segment posterior instrumentation without anterior column support is associated with a high incidence of implant failure and correction loss. This study was designed to evaluate the clinical and radiographic results following posterior short-segment instrumentation and limited segmental decompression supplemented with vertebroplasty with calcium sulphate and intermediate screws for patients with severe thoracolumbar burst fractures. METHODS: Twenty-eight patients with thoracolumbar burst fractures of LSC point 7 or more underwent this procedure. The average follow-up was 27.5 months. Demographic data, radiographic parameters, neurologic function, clinical outcomes and treatment-related complications were prospectively evaluated. RESULTS: Loss of vertebral body height and segmental kyphosis was 55.3 % and 20.2° before surgery, which significantly improved to 12.2 % and 5.4° at the final follow-up, respectively. Loss of kyphosis correction was 2.2°. The preoperative canal encroachment was 49 % that significantly improved to 8.8 %. The preoperative pain and function level showed a mean VAS score of 9.2 and ODI of 89.9 % that improved to 1.4 and 12.9 % at the final follow-up, respectively. No implant failure was observed in this series, and cement leakage occurred in two cases without clinical implications. CONCLUSIONS: Excellent reduction and maintenance of thoracolumbar burst fractures can be achieved with short-segment pedicle instrumentation supplemented with anterior column reconstruction and intermediate screws. The resultant circumferential stabilization combined with a limited segmental decompression resulted in improved neurologic function and satisfactory clinical outcomes, with a low incidence of implant failure and progressive deformity.

Research progress in decellularized extracellular matrix hydrogels for intervertebral disc degeneration.

As one of the most common clinical disorders, low back pain (LBP) influences patient quality of life and causes substantial social and economic burdens. Many factors can result in LBP, the most common of which is intervertebral disc degeneration (IDD). The progression of IDD cannot be alleviated by conservative or surgical treatments, and gene therapy, growth factor therapy, and cell therapy have their own limitations. Recently, research on the use of hydrogel biomaterials for the treatment of IDD has garnered great interest, and satisfactory treatment results have been achieved. This article describes the classification of hydrogels, the methods of decellularized extracellular matrix (dECM) production and the various types of gel formation. The current research on dECM hydrogels for the treatment of IDD is described in detail in this article. First, an overview of the material sources, decellularization methods, and gel formation methods is given. The focus is on research performed over the last three years, which mainly consists of bovine and porcine NP tissues, while for decellularization methods, combinations of several approaches are primarily used. dECM hydrogels have significantly improved mechanical properties after the polymers are cross-linked. The main effects of these gels include induction of stem cell differentiation to intervertebral disc (IVD) cells, good mechanical properties to restore IVD height after polymer cross-linking, and slow release of exosomes. Finally, the challenges and problems still faced by dECM hydrogels for the treatment of IDD are summarised, and potential solutions are proposed. This paper is the first to summarise the research on dECM hydrogels for the treatment of IDD and aims to provide a theoretical reference for subsequent studies.

Risk Factors for Hidden Blood Loss Associated with Vertebroplasty or Kyphoplasty for Osteoporotic Vertebral Compression Fracture: A Systematic Review and Meta-Analysis.

OBJECTIVE: Hidden blood loss (HBL), as a perioperative complication of percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP), affects the quality of life of older adults with poor health status, but it is often ignored by clinical surgeons. The purpose of this study was to discuss the risk factors for perioperative HBL through meta-analysis. METHODS: We systematically searched PubMed, Embase, Cochrane Library, Web of Science, Scopus, Google Scholar, Chinese National Knowledge Infrastructure, and Wan Fang from establishment of the database to September 2022. All eligible studies regarding risk factors for HBL after PVP or PKP were included. Heterogeneity was assessed using the χ2 test and I2 statistic percentages. If I2 >50% or P < 0.1, the random-effect model was used; otherwise, the fixed-effect model was used. Data were analyzed with Revman 5.4 and Stata 16.0. RESULTS: Eleven studies involving 1506 patients were included and the average HBL of PKP and PVP was 278.57 mL and 276.12mL. The results showed that bone cement leakage (P < 0.0001), thoracic vertebra (P < 0.00001), bilateral surgical approach (P = 0.0008), ≥2 fracture segments (P < 0.00001), vertebral body height loss rate (≥1/3) (P < 0.00001), and vertebral body height restoration rate (≥1/3) (P < 0.00001) were risk factors for increased HBL. Diabetes (P = 0.12) and hypertension (P = 0.52) were not significantly associated with HBL. CONCLUSIONS: The findings of this meta-analysis suggested that fracture level, surgical approach, number of fracture levels, cement leakage, vertebral height loss and restoration rate were significant risk factors for HBL, which had certain guiding significance for clinical surgeons to take reasonable measures to deal with this complication.

Biomechanical Evaluation of Spinal Column after Percutaneous Cement Discoplasty: A Finite Element Analysis.

OBJECTIVE: To compare the biomechanical properties of percutaneous cement discoplasty (PCD) in the spinal column between different implant-endplate friction. METHODS: A validated L3-Scarumfinite element (FE) model was modified for simulation. In the PCD model, the L4/5 level was modified based on model 1 (M1) and model 2 (M2). In M1, the interaction between bone cement and endplate was defined as face-to-face contact with a friction coefficient of 0.3; in M2, the contact was defined as a Tie constraint. 7.5 N m moments of four physiological motions and axial load of 15, 100 and 400 N preload were imposed at the top of L3. The range of motion (ROM) and interface stress analysis of endplates, annulus fibrosus and bone cement of the operated level were calculated for comparisons among the three models. RESULTS: The ROM of M1 and M2 increased when compared with the intact model during flexion (FL) (17.5% vs 10.0%), extension (EX) (8.8% vs -8.8%), left bending (LB) (19.0% vs -17.2%) and left axial rotation (LR) (34.6% vs -3.8%). The stress of annulus fibrosus in M1 and M2 decreased in FL (-48.4% vs -57.5%), EX (-25.7% vs -14.7%), LB (-47.5% vs -52.4%), LR (-61.4% vs -68.7%) and axis loading of 100 N (-41.5% vs -15.3%), and 400 N (-27.9% vs -27.3%). The stress of upper endplate of M1 and M2 increased in FL (24.6% vs 24.7%), LB (82.2% vs 89.5%), LR (119% vs 62.4%) and axis loading of 100 N (64.6% vs 45.5%), and 400 N (58.2% vs 24.3%), but was similar in EX (2.9% vs 0.3%). The stress of lower endplate of M1 and M2 increased in FL (170.9% vs 175.0%), EX (180.8% vs 207.7%), LB (302.6% vs 274.7%), LR (332.4% vs 132.8%) and axis loading of 100 N (350.7% vs 168.6%), and 400 N (165.2% vs 106.7%). CONCLUSION: Percutaneous cement discoplasty procedure could make effect on the mobility or stiffness. The fusion of bone cement and endplate might have more biomechanical advantages, including of the decreasing rate of implant subsidence and dislocation, and the increase spine stability.

Construction of chitosan scaffolds with controllable microchannel for tissue engineering and regenerative medicine.

Microchannels are effective means of enabling the functional performance of tissue engineering scaffolds. Chitosan, a partial deacetylation derivative of chitin, exhibiting excellent biocompatibility, has been widely used in clinical practice. However, development of chitosan scaffolds with controllable microchannels architecture remains an engineering challenge. Here, we generated chitosan scaffolds with adjustable microchannel by combining a 3D printing microfiber templates-leaching method and a freeze-drying method. We can precisely control the arrangement, diameter and density of microchannel within chitosan scaffolds. Moreover, the integrated bilayer scaffolds with the desired structural parameters in each layer were fabricated and exhibited no delamination. The flow rate and volume of the simulated fluid can be modulated by diverse channels architecture. Additionally, the microchannel structure promoted cell survival, proliferation and distribution in vitro, and improved cell and tissue ingrowth and vascular formation in vivo. This study opens a new road for constructing chitosan scaffolds, and can further extend their application scope across tissue engineering and regenerative medicine.

Comparison of decellularization protocols for preparing a decellularized porcine annulus fibrosus scaffold.

Tissue-specific extracellular matrix plays an important role in promoting tissue regeneration and repair. We hypothesized that decellularized annular fibrosus matrix may be an appropriate scaffold for annular fibrosus tissue engineering. We aimed to determine the optimal decellularization method suitable for annular fibrosus. Annular fibrosus tissue was treated with 3 different protocols with Triton X-100, sodium dodecyl sulfate (SDS) and trypsin. After the decellularization process, we examined cell removal and preservation of the matrix components, microstructure and mechanical function with the treatments to determine which method is more efficient. All 3 protocols achieved decellularization; however, SDS or trypsin disturbed the structure of the annular fibrosus. All protocols maintained collagen content, but glycosaminoglycan content was lost to different degrees, with the highest content with TritonX-100 treatment. Furthermore, SDS decreased the tensile mechanical property of annular fibrosus as compared with the other 2 protocols. MTT assay revealed that the decellularized annular fibrosus was not cytotoxic. Annular fibrosus cells seeded into the scaffold showed good viability. The Triton X-100-treated annular fibrosus retained major extracellular matrix components after thorough cell removal and preserved the concentric lamellar structure and tensile mechanical properties. As well, it possessed favorable biocompatibility, so it may be a suitable candidate as a scaffold for annular fibrosus tissue engineering.

[Histological structure and cytocompatibility of novel acellular bone matrix scaffold].

OBJECTIVE: To observe the histological structure and cytocompatibility of novel acellular bone matrix (ACBM) and to investigate the feasibility as a scaffold for bone tissue engineering. METHODS: Cancellous bone columns were harvested from the density region of 18-24 months old male canine femoral head, then were dealt with high-pressure water washing, degreasing, and decellularization with Trixon X-100 and sodium deoxycholate to prepare the ACBM scaffold. The scaffolds were observed by scanning electron microscope (SEM); HE staining, Hoechst 33258 staining, and sirius red staining were used for histological analysis. Bone marrow mesenchymal stem cells (BMSCs) from canine were isolated and cultured with density gradient centrifugation; the 3rd passage BMSCs were seeded onto the scaffold. MTT test was done to assess the cytotoxicity of the scaffolds. The proliferation and differentiation of the cells on the scaffold were observed by inverted microscope, SEM, and live/dead cell staining method. RESULTS: HE staining and Hoechst 33258 staining showed that there was no cell fragments in the scaffolds; sirius red staining showed that the ACBM scaffold was stained crimson or red and yellow alternating. SEM observation revealed a three dimensional interconnected porous structure, which was the microstructure of normal cancellous bone. Cytotoxicity testing with MTT revealed no significant difference in absorbance (A) values between different extracts (25%, 50%, and 100%) and H-DMEM culture media (P > 0.05), indicating no cytotoxic effect of the scaffold on BMSCs. Inverted microscope, SEM, and histological analysis showed that three dimensional interconnected porous structure of the scaffold supported the proliferation and attachment of BMSCs, which secreted abundant extracellular matrices. Live/dead cell staining results of cell-scaffold composites revealed that the cells displaying green fluorescence were observed. CONCLUSION: Novel ACBM scaffold can be used as an alternative cell-carrier for bone tissue engineering because of thoroughly decellularization, good mircostructure, non-toxicity, and good cytocompatibility.

Long-term results and radiographic findings of percutanous vertebroplasties with polymethylmethacrylate for vertebral osteoporotic fractures.

BACKGROUND: Percutaneous vertebroplasty (PVP) has become a popular procedure for painful vertebral osteoporotic fracture (VOF), with immediate pain relief and improved mobility; however, polymethylmethacrylate (PMMA) injected into the vertebral body is not absorbable and little information is available concerning the long-term results. In this retrospective study, we evaluated the long-term clinical results and radiological changes after PVPs for VOFs. METHODS: Fifty-one patients with VOFs were treated by PVPs with PMMA between 2000 and 2004. After > 7 years of follow-up, eight patients had died from causes unrelated to the intervention and 12 patients were lost to follow-up, thus leaving 31 patients available for evaluation with an average length of follow-up of 9.2 years (follow-up rate, 72.1%). Among these 31 patients, the PMMA was injected at 43 levels with a mean volume of 4.3 ml per level (range, 2 - 6 ml). The pain was assessed with a visual analog scale (VAS), and the mobility was graded as walking without difficulty (grade 1), walking with assistance (grade 2), and bedridden (grade 3). Plain radiographs and computed tomography (CT) were obtained and assessed pre-operatively, immediately post-operatively, and after 7 years of follow-up. The PMMA, vertebral height, and Cobb angle were assessed and compared. RESULTS: All of the patients experienced pain relief and improved mobility after intervention and during the follow-up period. Cement leakage was detected in post-operative CT scans in 9 of 51 patients, but without neurological compromise. For the 31 patients followed up over 7 years, the VAS decreased from 8.3 ± 2.6 pre-operatively, to 2.1 ± 1.6 immediately post-operatively, and 1.0 ± 0.9 at the final follow-up evaluation, with significantly improved mobility. Additional compression fractures occurred at adjacent levels in three patients, and there were no new fractures at the augmented vertebrae. Based on a review of the radiographs, neither loose nor displaced cement was detected. The changes in vertebral height and Cobb angle were not significant. On CT scans, the cement closely contacted or infiltrated the trabecular bone. The boundary between the cement and trabecular bone was indistinct and there was no evident radiolucent gap between the cement and trabecular bone. CONCLUSIONS: At an average follow-up of 9.2 years, PVPs provided sustained pain relief and improved mobility in patients with VOFs. The PMMA injected into the vertebral body combined closely with the host trabecular bone without adverse reactions.