The Application of Biomaterials in Spinal Cord Injury.

The spinal cord and the brain form the central nervous system (CNS), which is the most important part of the body. However, spinal cord injury (SCI) caused by external forces is one of the most difficult types of neurological injury to treat, resulting in reduced or even absent motor, sensory and autonomic functions. It leads to the reduction or even disappearance of motor, sensory and self-organizing nerve functions. Currently, its incidence is increasing each year worldwide. Therefore, the development of treatments for SCI is urgently needed in the clinic. To date, surgery, drug therapy, stem cell transplantation, regenerative medicine, and rehabilitation therapy have been developed for the treatment of SCI. Among them, regenerative biomaterials that use tissue engineering and bioscaffolds to transport cells or drugs to the injured site are considered the most promising option. In this review, we briefly introduce SCI and its molecular mechanism and summarize the application of biomaterials in the repair and regeneration of tissue in various models of SCI. However, there is still limited evidence about the treatment of SCI with biomaterials in the clinic. Finally, this review will provide inspiration and direction for the future study and application of biomaterials in the treatment of SCI.

Tooth loss and the risk of cognitive decline and dementia: A meta-analysis of cohort studies.

Introduction: Epidemiological studies have shown that tooth loss may be associated with an increased risk of cognitive decline and dementia. However, some results do not show a significant association. Therefore, we performed a meta-analysis to evaluate this association. Methods: Relevant cohort studies were searched in PubMed, Embase, Web of Science (up to May 2022), and the reference lists of retrieved articles. The pooled relative risk (RR) and 95% confidence intervals were computed using a random-effects model (CI). Heterogeneity was evaluated using the I 2 statistic. Publication bias was evaluated using the Begg's and Egger's tests. Results: Eighteen cohort studies met the inclusion criteria. Original studies with 356,297 participants with an average follow-up of 8.6 years (ranging from 2 to 20 years) were included in this study. The pooled RRs of tooth loss on dementia and cognitive decline were 1.15 (95% CI: 1.10-1.20; P < 0.01, I 2 = 67.4%) and 1.20 (95% CI: 1.14-1.26; P = 0.04, I 2 = 42.3%), respectively. The results of the subgroup analysis showed an increased association between tooth loss and Alzheimer's disease (AD) (RR = 1.12, 95% CI: 1.02-1.23) and vascular dementia (VaD) (RR = 1.25, 95% CI: 1.06-1.47). The results of the subgroup analysis also showed that pooled RRs varied by geographic location, sex, use of dentures, number of teeth or edentulous status, dental assessment, and follow-up duration. None of the Begg's and Egger's tests or funnel plots showed evidence of publication bias. Discussion: Tooth loss is associated with a significantly increased risk of cognitive decline and dementia, suggesting that adequate natural teeth are important for cognitive function in older adults. The likely mechanisms mostly suggested include nutrition, inflammation, and neural feedback, especially deficiency of several nutrients like vitamin D.

Comparison of stand-alone polyetheretherketone cages and iliac crest autografts for the treatment of cervical degenerative disc diseases.

BACKGROUND: Anterior cervical decompression and fusion (ACDF) is a widely accepted surgical procedure for the treatment of cervical degenerative disc diseases. This retrospective study was designed to analyze and compare the efficacy and outcomes of anterior cervical fusion using stand-alone polyetheretherketone (PEEK) cages and autogenous iliac crest grafts with the anterior cervical plating system. METHODS: A total of 72 consecutive patients suffering from cervical degenerative disc diseases treated with ACDF from June 2005 to Dec 2008 were enrolled in the study. Patients in group A (40 patients, 64 segments) had anterior interbody fusion with stand-alone PEEK cages and patients in group B (32 patients, 51 segments) with autogenous iliac crest graft combined with anterior plate fixation. The operative time and intraoperative blood loss were recorded. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system; cervical lordosis, intervertebral height, and cervical fusion status were assessed on X-ray and computed tomography. FINDINGS: The mean follow-up period was 17.3 months in the stand-alone cage group and 23.2 months in the autologous iliac crest graft group. The operative time and intraoperative blood loss in group A were much less than those in group B (p < 0.05). All the patients in both groups got complete interbody fusion. Postoperative JOA scores in both group A and group B were more than the preoperative ones with significant differences, and the improvement rate of JOA scores had no statistical differences between group A and group B. Postoperative cervical physiological curvature and intervertebral height in both groups were better than the preoperative ones with statistical significances. CONCLUSIONS: The stand-alone PEEK cage is a good substitute for fusion in patients with cervical disc disease; it can effectively restore the cervical physiological curvature and the intervertebral height, facilitate radiological follow-up, cause few complications, and leads to satisfactory outcomes.

Concentration-Dependent Regulation of TiAl6V4 Particles on the Osteogenesis Potential of Human Bone Marrow Mesenchymal Stem Cells.

Total joint replacement is one of the most effective treatments for osteoarthritis, while the aseptic loosening of artificial joint is a major complication leading to the joint replacement failure. There are very limited studies about the effects of titanium-alloy particles on the osteogenic differentiation of mesenchymal stem cells. In this study, human bone marrow-derived mesenchymal stem cells (BM-hMSCs) were treated with different concentrations of TiAl6V4 particles. The cell viability was detected by MTT assay, and the cell proliferation was assessed by CKK-8 assay. The early and late stages of osteogenic differentiation were determined by alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining assays. The expression of osteogenic genes and proteins was analyzed by RT-PCR and Western blot. TiAl6V4 particles at high concentration 100 µg/ml inhibited the cell viability of BM-hMSCs. However, TiAl6V4 in the range of 5-50 µg/ml did not show effects neither on the cell viability nor on the cell proliferation of BM-hMSCs. TiAl6V4 particles showed concentration-dependent bidirectional regulations on BM-hMSC osteogenesis. Specifically, TiAl6V4 at 5 µg/ml promoted the osteogenesis of BM-hMSCs, which was suppressed by TiAl6V4 at 50 µg/ml. Further, mechanism study revealed that the regulation of TiAl6V4 on BM-hMSCs was related to Wnt signaling pathway. Given the potential of mesenchymal cells, our study suggested that the minimization of metal use would be an attractive strategy to reduce the joint replacement failure.

Three-level anterior cervical discectomy and fusion with self-locking stand-alone polyetheretherketone cages.

Anterior cervical plating is regarded as standard practice after multilevel anterior cervical discectomy and fusion. However, plate implantation in the anterior cervical spine poses a substantial risk of hardware-related complications. We retrospectively analyzed the efficacy and outcomes of 15 consecutive patients treated with a 3-level anterior cervical fusion using self-locking stand-alone polyetheretherketone (PEEK) cages. Patients were evaluated preoperatively and postoperatively using the Japanese Orthopedic Association (JOA) scale scores and radiographs. Clinical results were assessed using Odom's criteria. The mean JOA score (± standard deviation) improved significantly from 7.3 ± 1.5 points to 14.1 ± 1.3 points (p < 0.05) at the final follow-up. The outcomes were excellent for four patients (26.7%), good for nine patients (60%) and fair for two patients (13.3%). None of the patients experienced a poor clinical outcome. Thirteen patients achieved a solid fusion, after an average time of 5.7 months. The radiographic fusion rate of this procedure was 93.3%. Of 45 cages inserted in total, only four (8.89%) cages, in three patients, were found to have subsided. The degree of spinal curvature before surgery differed significantly from that immediately after surgery, and from that at the final follow-up examination (p < 0.05). Self-locking stand-alone PEEK cages packed with excised local osteophytes and calcium sulfate are safe and effective. This procedure can effectively restore cervical lordosis, obviate the complications related to graft harvest and screw-plate fixation, and lead to satisfactory outcomes.