Xijing He

The incidence of adjacent segment degeneration after cervical disc arthroplasty (CDA): a meta analysis of randomized controlled trials.

Background Cervical disc arthroplasty is being used as an alternative degenerative disc disease treatment with fusion of the cervical spine in order to preserve motion. However, whether replacement arthoplasty in the spine achieves its primary patient centered objective of lowering the frequency of adjacent segment degeneration is not verified yet. Methodology We conducted a meta-analysis according to the guidelines of the Cochrane Collaboration using databases including PubMed, Cochrane Central Register of Controlled Trials and Embase. The inclusion criteria were: 1) Randomized, controlled study of degenerative disc disease of the cervical spine involving single segment or double segments using Cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) as controls; 2) A minimum of two-year follow-up using imaging and clinical analyses; 3) Definite diagnostic evidences for “adjacent segment degeneration” and “adjacent segment disease”; 4) At least a minimum of 30 patients per population. Two authors independently selected trials; assessed methodological quality, extracted data and the results were pooled. Results No study has specifically compared the results of adjacent segment degenerative; Two papers describing 140 patients with 162 symptomatic cervical segment disorders and compared the rate of postoperative adjacent segment disease development between CDA and ACDF treatments, three publications describing the rate of adjacent-segment surgery including 1273 patients with symptomatic cervical segments. The result of the meta-analysis indicates that there were fewer the rate of adjacent segment disease and the rate for adjacent-segment surgery comparing CDA with ACDF, but the difference was not statistically significant. Conclusions Based on available evidence, it cannot be concluded, that CDA can significantly reduce the postoperative rate of the adjacent segment degenerative and adjacent segment disease. However, due to some limitations, the results of this meta-analysis should be cautiously accepted, and further studies are needed.

Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury (SCI) is a devastating type of neurological trauma with limited therapeutic opportunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contributor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of microglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.

Systematic Review and Meta-Analysis of Perioperative Intravenous Tranexamic Acid Use in Spinal Surgery

Background Tranexamic acid (TXA) is well-established as a versatile oral, intramuscular, and intravenous (IV) antifibrinolytic agent. However, the efficacy of IV TXA in reducing perioperative blood transfusion in spinal surgery is poorly documented. Methodology We conducted a meta-analysis of randomized controlled trials (RCTs) and quasi-randomized (qi-RCTs) trials that included patients for various spinal surgeries, such as adolescent scoliosis surgery administered with perioperative IV TXA according to Cochrane Collaboration guidelines using electronic PubMed, Cochrane Central Register of Controlled Trials, and Embase databases. Additional journal articles and conference proceedings were manually located by two independent researchers. Results Totally, nine studies were included, with a total sample size of 581 patients. Mean blood loss was decreased in patients treated with perioperative IV TXA by 128.28 ml intraoperatively (ranging from 33.84 to 222.73 ml), 98.49 ml postoperatively (ranging from 83.22 to 113.77 ml), and 389.21 ml combined (ranging from 177.83 to 600.60 ml). The mean volume of transfused packed cells were reduced by 134.55 ml (ranging 51.64 to 217.46) (95% CI; P = 0.0001). Overall, the number of patients treated with TXA who required blood transfusions was lower by 35% than that of patients treated with the comparator and who required blood transfusions (RR 0.65; 95% CI; 0.53 to 0.85; P<0.0001, I2 = 0%). A dose-independent beneficial effect of TXA was observed, and confirmed in subgroup and sensitivity analyses. A total of seven studies reported DVT data. The study containing only a single DVT case was not combined. Conclusions The blood loss was reduced in spinal surgery patients with perioperative IV TXA treatment. Also the percentage of spinal surgery patients who required blood transfusion was significantly decreased. Further evaluation is required to confirm our findings before TXA can be safely used in patients undergoing spine surgery.

Macrophages in Spinal Cord Injury: Phenotypic and Functional Change From Exposure to Myelin Debris

Macrophage activation and persistent inflammation contribute to the pathological process of spinal cord injury (SCI). It was reported that M2 macrophages were induced at 3–7 days after SCI but M2 markers were reduced or eliminated after 1 week. By contrast, M1 macrophage response is rapidly induced and then maintained at injured spinal cord. However, factors that modulate macrophage phenotype and function are poorly understood. We developed a model to distinguish bone‐marrow derived macrophages (BMDMs) from residential microglia and explored how BMDMs change their phenotype and functions in response to the lesion‐related factors in injured spinal cord. Infiltrating BMDMs expressing higher Mac‐2 and lower CX3CR1 migrate to the epicenter of injury, while microglia expressing lower Mac‐2 but higher CX3CR1 distribute to the edges of lesion. Myelin debris at the lesion site switches BMDMs from M2 phenotype towards M1‐like phenotype. Myelin debris activates ATP‐binding cassette transporter A1 (ABCA1) for cholesterol efflux in response to myelin debris loading in vitro. However, this homeostatic mechanism in injured site is overwhelmed, leading to the development of foamy macrophages and lipid plaque in the lesion site. The persistence of these cells indicates a pro‐inflammatory environment, associated with enhanced neurotoxicity and impaired wound healing. These foamy macrophages have poor capacity to phagocytose apoptotic neutrophils resulting in uningested neutrophils releasing their toxic contents and further tissue damage. In conclusion, these data demonstrate for the first time that myelin debris generated in injured spinal cord modulates macrophage activation. Lipid accumulation following macrophage phenotype switch contributes to SCI pathology. GLIA 2015;63:635–651

Lithium Suppresses Astrogliogenesis by Neural Stem and Progenitor Cells by Inhibiting STAT3 Pathway Independently of Glycogen Synthase Kinase 3 Beta

Transplanted neural stem and progenitor cells (NSCs) produce mostly astrocytes in injured spinal cords. Lithium stimulates neurogenesis by inhibiting GSK3b (glycogen synthetase kinase 3-beta) and increasing WNT/beta catenin. Lithium suppresses astrogliogenesis but the mechanisms were unclear. We cultured NSCs from subventricular zone of neonatal rats and showed that lithium reduced NSC production of astrocytes as well as proliferation of glia restricted progenitor (GRP) cells. Lithium strongly inhibited STAT3 (signal transducer and activator of transcription 3) activation, a messenger system known to promote astrogliogenesis and cancer. Lithium abolished STAT3 activation and astrogliogenesis induced by a STAT3 agonist AICAR (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), suggesting that lithium suppresses astrogliogenesis by inhibiting STAT3. GSK3β inhibition either by a specific GSK3β inhibitor SB216763 or overexpression of GID5-6 (GSK3β Interaction Domain aa380 to 404) did not suppress astrogliogenesis and GRP proliferation. GSK3β inhibition also did not suppress STAT3 activation. Together, these results indicate that lithium inhibits astrogliogenesis through non-GSK3β-mediated inhibition of STAT. Lithium may increase efficacy of NSC transplants by increasing neurogenesis and reducing astrogliogenesis. Our results also may explain the strong safety record of lithium treatment of manic depression. Millions of people take high-dose (>1 gram/day) lithium carbonate for a lifetime. GSK3b inhibition increases WNT/beta catenin, associated with colon and other cancers. STAT3 inhibition may reduce risk for cancer.

4q22.1 contributes to bone mineral density and osteoporosis susceptibility in postmenopausal women of Chinese Han population.

Osteoporosis is a multifactorial disease in which genetic determinants are modulated by hormonal, environmental and nutritional factors. An important clinical risk factor in the pathogenesis of osteoporosis is the presence of genetics polymorphism in/around susceptibility genes/regions. This study explored whether the region of 4q22.1, which confers risk of developing osteoporosis in some populations, associated with bone mineral density and osteoporosis susceptibility in postmenopausal women of Han Chinese. We investigated 32 SNPs with minor allele frequencies ≥0.05 between 20 kb upstream and 20 kb downstream (40 kb window) of rs6532023, mapping in the 4q22.1 region, which was reported to be significantly associated with osteoporosis in previous studies. We found that rs6532023 was significantly associated with bone mineral density and osteoporosis (corrected p = 0.015) in our sample, including 440 cases and 640 controls, and allele G was supposed as a risk factor while T worked as a protective factor. Further genotype association analyses suggested a similar pattern (corrected p = 0.040). Additionally, analyses by haplotypes indicated that a haplotype block rs7683315-rs6532023-rs1471400-rs1471403 in the region associated with bone mineral density and osteoporosis (global p = 0.032), and risk haplotype A-G-G-C had almost 1.5-fold increased in the cases. To our knowledge, this is the first report to examine 4q22.1 region polymorphisms and osteoporosis in Han Chinese. Our results provide further evidence for an effect of the region of 4q22.1 on the etiology of osteoporosis and suggest that 4q22.1 may be a genetic risk factor for bone mineral density and osteoporosis.

Effects of aloesin on melanogenesis in pigmented skin equivalents

Reconstituted 3‐dimensional human skin equivalents in vitro are gaining popularity for studies of skin metabolism and depigmenting agents because they exhibit morphological and growth characteristics similar to human skin. The effects of aloesin on melanogenesis, however, have never been examined with the pigmented skin equivalent. The purpose of the study was to construct the skin equivalent and observe the effects of aloesin on melanogenesis in the model. We constructed an in vitro pigmented skin equivalent and examined the general structure and condition of the pigmented skin equivalent with H&E staining and Fontana Masson staining. Then, we examined the effects of aloesin on tyrosinase activity and formation of melanin in the model. Such a pigmented skin model demonstrated morphology similar to that seen in normal skin and can be used to assess the regulation of pigmentation by melanogenic compounds. The results suggested that aloesin had direct inhibitory effects on melanogenesis and showed dose‐dependent reductions in tyrosinase activity (P < 0.05) and melanin content (P < 0.05). In conclusion, our study indicated that skin equivalents provided a convenient and cost‐effective alternative to animal testing for evaluating the regulation of pigmentation. Aloesin showed promise as a pigmentation‐altering agent for cosmetic or therapeutic applications.

Anti-Inflammatory Mechanism of Neural Stem Cell Transplantation in Spinal Cord Injury

Neural stem cell (NSC) transplantation has been proposed to promote functional recovery after spinal cord injury. However, a detailed understanding of the mechanisms of how NSCs exert their therapeutic plasticity is lacking. We transplanted mouse NSCs into the injured spinal cord seven days after SCI, and the Basso Mouse Scale (BMS) score was performed to assess locomotor function. The anti-inflammatory effects of NSC transplantation was analyzed by immunofluorescence staining of neutrophil and macrophages and the detection of mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-12 (IL-12). Furthermore, bone marrow-derived macrophages (BMDMs) were co-cultured with NSCs and followed by analyzing the mRNA levels of inducible nitric oxide synthase (iNOS), TNF-α, IL-1β, IL-6 and IL-10 with quantitative real-time PCR. The production of TNF-α and IL-1β by BMDMs was examined using the enzyme-linked immunosorbent assay (ELISA). Transplanted NSCs had significantly increased BMS scores (p < 0.05). Histological results showed that the grafted NSCs migrated from the injection site toward the injured area. NSCs transplantation significantly reduced the number of neutrophils and iNOS+/Mac-2+ cells at the epicenter of the injured area (p < 0.05). Meanwhile, mRNA levels of TNF-α, IL-1β, IL-6 and IL-12 in the NSCs transplantation group were significantly decreased compared to the control group. Furthermore, NSCs inhibited the iNOS expression of BMDMs and the release of inflammatory factors by macrophages in vitro (p < 0.05). These results suggest that NSC transplantation could modulate SCI-induced inflammatory responses and enhance neurological function after SCI via reducing M1 macrophage activation and infiltrating neutrophils. Thus, this study provides a new insight into the mechanisms responsible for the anti-inflammatory effect of NSC transplantation after SCI.

Embryonic stem cells promoting macrophage survival and function are crucial for teratoma development

Stem cell therapies have had tremendous potential application for many diseases in recent years. However, the tumorigenic properties of stem cells restrict their potential clinical application; therefore, strategies for reducing the tumorigenic potential of stem cells must be established prior to transplantation. We have demonstrated that syngeneic transplantation of embryonic stem cells (ESCs) provokes an inflammatory response that involves the rapid recruitment of bone marrow-derived macrophages (BMDMs). ESCs are able to prevent mature macrophages from macrophage colony-stimulating factor (M-CSF) withdrawal-induced apoptosis, and thus prolong macrophage lifespan significantly by blocking various apoptotic pathways in an M-CSF-independent manner. ESCs express and secrete IL-34, which may be responsible for ESC-promoted macrophage survival. This anti-apoptotic effect of ESCs involves activation of extracellular signal-regulated kinase (ERK)1/2 and PI3K/Akt pathways and thus, inhibition of ERK1/2 and PI3K/AKT activation decreases ESC-induced macrophage survival. Functionally, ESC-treated macrophages also showed a higher level of phagocytic activity. ESCs further serve to polarize BMDMs into M2-like macrophages that exhibit most tumor-associated macrophage phenotypic and functional features. ESC-educated macrophages produce high levels of arginase-1, Tie-2, and TNF-α, which participate in angiogenesis and contribute to teratoma progression. Our study suggests that induction of M2-like macrophage activation is an important mechanism for teratoma development. Strategies targeting macrophages to inhibit teratoma development would increase the safety of ESC-based therapies, inasmuch as the depletion of macrophages completely inhibits ESC-induced angiogenesis and teratoma development.

Biomechanical study of anterior cervical corpectomy and step-cut grafting with bioabsorbable screws fixation in cadaveric cervical spine model.

Study Design. An in vitro biomechanical study. Objective. To determine the initial stability of a novel construct in a 1-level cadaveric cervical spine model by comparing it with a conventional method. Summary of Background Data. Lots of endeavors have been made to enhance fusion rates and reduce complications in the anterior cervical spine procedure. Methods. There were 12 fresh human cadaveric cervical spines (C3–C7) randomly divided into 2 groups: group 1, 1-level corpectomy of C5 and step-cut grafting with bioabsorbable screw fixation (SCAS); and group 2, 1-level corpectomy of C5 and strut grafting with anterior plate fixation (SP). For each specimen, the intact underwent a flexibility test first, followed by the instrumented construct. Rotational angles of the C4–C6 segment were measured to study the immediate stability of anterior cervical corpectomy and SCAS, compared with the intact and anterior cervical corpectomy and SP. Results. Both anterior cervical corpectomy with SCAS and with SP significantly (P < 0.01) decreased the motions of C4–C6 in all 6 degrees of freedom after instrumentation. Compared with anterior cervical corpectomy and SP, anterior cervical corpectomy and SCAS had higher stability (P < 0.05) in extension, and comparable stability (P > 0.05) in flexion and axial rotation, but lower stability (P ≤ 0.05) in lateral bending. Conclusion. Anterior cervical corpectomy and SCAS, a novel method of anterior cervical spine decompression and reconstruction, was introduced. The in vitro biomechanical study showed that anterior cervical corpectomy and SCAS had sufficient immediate stability except for the lateral bending, compared with anterior cervical corpectomy and SP, in a 1-level cadaveric cervical spine model. However, an animal experimental in vivo evaluation of anterior cervical corpectomy and SCAS still has to be performed.