Zengjie Zhang

Sirt6 overexpression suppresses senescence and apoptosis of nucleus pulposus cells by inducing autophagy in a model of intervertebral disc degeneration

Treatment of intervertebral disc degeneration (IDD) seeks to prevent senescence and death of nucleus pulposus (NP) cells. Previous studies have shown that sirt6 exerts potent anti-senescent and anti-apoptotic effects in models of age-related degenerative disease. However, it is not known whether sirt6 protects against IDD. Here, we explored whether sirt6 influenced IDD. The sirt6 level was reduced in senescent human NP cells. Sirt6 overexpression protected against apoptosis and both replicative and stress-induced premature senescence. Sirt6 also activated NP cell autophagy both in vivo and in vitro. 3-methyladenine (3-MA) and chloroquine (CQ)-mediated inhibition of autophagy partially reversed the anti-senescent and anti-apoptotic effects of sirt6, which regulated the expression of degeneration-associated proteins. In vivo, sirt6 overexpression attenuated IDD. Together, the data showed that sirt6 attenuated cell senescence, and reduced apoptosis, by triggering autophagy that ultimately ameliorated IDD. Thus, sirt6 may be a novel therapeutic target for IDD treatment.

Salidroside attenuates neuroinflammation and improves functional recovery after spinal cord injury through microglia polarization regulation

Spinal cord injury (SCI) is a severe neurological disease; however, few drugs have been proved to treat SCI effectively. Neuroinflammation is the major pathogenesis of SCI secondary injury and considered to be the therapeutic target of SCI. Salidroside (Sal) has been reported to exert anti‐inflammatory effects in airway, adipose and myocardial tissue; however, the role of Sal in SCI therapeutics has not been clarified. In this study, we showed that Sal could improve the functional recovery of spinal cord in rats as revealed by increased BBB locomotor rating scale, angle of incline, and decreased cavity of spinal cord injury and apoptosis of neurons in vivo. Immunofluorescence double staining of microglia marker and M1/M2 marker demonstrated that Sal could suppress M1 microglia polarization and activate M2 microglia polarization in vivo. To verify how Sal exerts its effects on microglia polarization and neuron protection, we performed the mechanism study in vitro in microglia cell line BV‐2 and neuron cell line PC12. The results showed that Sal prevents apoptosis of PC12 cells in coculture with LPS‐induced M1 BV‐2 microglia, also the inflammatory secretion phenotype of M1 BV‐2 microglia was suppressed by Sal, and further studies demonstrated that autophagic flux regulation through AMPK/mTOR pathway was involved in Sal regulated microglia polarization after SCI. Overall, our study illustrated that Sal could promote spinal cord injury functional recovery in rats, and the mechanism may relate to its microglia polarization modulation through AMPK‐/mTOR‐mediated autophagic flux stimulation.

Monotropein promotes angiogenesis and inhibits oxidative stress-induced autophagy in endothelial progenitor cells to accelerate wound healing

Attenuating oxidative stress‐induced damage and promoting endothelial progenitor cell (EPC) differentiation are critical for ischaemic injuries. We suggested monotropein (Mtp), a bioactive constituent used in traditional Chinese medicine, can inhibit oxidative stress‐induced mitochondrial dysfunction and stimulate bone marrow‐derived EPC (BM‐EPC) differentiation. Results showed Mtp significantly elevated migration and tube formation of BM‐EPCs and prevented tert‐butyl hydroperoxide (TBHP)‐induced programmed cell death through apoptosis and autophagy by reducing intracellular reactive oxygen species release and restoring mitochondrial membrane potential, which may be mediated viamTOR/p70S6K/4EBP1 and AMPK phosphorylation. Moreover, Mtp accelerated wound healing in rats, as indicated by reduced healing times, decreased macrophage infiltration and increased blood vessel formation. In summary, Mtp promoted mobilization and differentiation of BM‐EPCs and protected against apoptosis and autophagy by suppressing the AMPK/mTOR pathway, improving wound healing in vivo. This study revealed that Mtp is a potential therapeutic for endothelial injury‐related wounds.

Highly efficient local delivery of endothelial progenitor cells significantly potentiates angiogenesis and full-thickness wound healing

Wound therapy with a rapid healing performance remains a critical clinical challenge. Cellular delivery is considered to be a promising approach to improve the efficiency of healing, yet problems such as compromised cell viability and functionality arise due to the inefficient delivery. Here, we report the efficient delivery of endothelial progenitor cells (EPCs) with a bioactive nanofibrous scaffold (composed of collagen and polycaprolactone and bioactive glass nanoparticles, CPB) for enhancing wound healing. Under the stimulation of CPB nanofibrous system, the viability and angiogenic ability of EPCs were significantly enhanced through the activation of Hif-1α/VEGF/SDF-1α signaling. In vivo, CPB/EPC constructs significantly enhanced the formation of high-density blood vessels by greatly upregulating the expressions of Hif-1α, VEGF, and SDF-1α. Moreover, owing to the increased local delivery of cells and fast neovascularization within the wound site, cell proliferative activity, granulation tissue formation, and collagen synthesis and deposition were greatly promoted by CPB/EPC constructs resulting in rapid re-epithelialization and regeneration of skin appendages. As a result, the synergistic enhancement of wound healing was observed from CPB/EPC constructs, which suggests the highly efficient delivery of EPCs. CPB/EPC constructs may become highly competitive cell-based therapeutic products for efficient impaired wound healing application. This study may also provide a novel strategy to develop bioactive cell therapy constructs for angiogenesis-related regenerative medicine.nnnSTATEMENT OF SIGNIFICANCEnThis paper reported a highly efficient local delivery of EPCs using bioactive glass-based CPB nanofibrous scaffold for enhancing angiogenesis and wound regeneration. In vitro study showed that CPB can promote the proliferation, migration, and tube formation of EPCs through upregulation of the Hif-1α/VEGF/SDF-1α signaling pathway, indicating that the bioactivity and angiogenic ability of EPCs can be highly maintained and promoted by the CPB scaffold. Moreover, CPB/EPC constructs effectively stimulated the regeneration of diabetic wounds with satisfactory vascularization and better healing outcomes in a full-thickness wound model, suggesting that the highly efficient delivery of EPCs to wound site facilitates angiogenesis and further leads to wound healing. The high angiogenic capacity and excellent healing ability make CPB/EPC constructs highly competitive in cell-based therapeutic products for efficient wound repair application.

Berberine suppresses apoptosis and extracellular matrix (ECM) degradation in nucleus pulposus cells and ameliorates disc degeneration in a rodent model

Intervertebral disc degeneration (IVDD) is a chronic disease with complicated pathology involving nucleus pulposus (NP) cell apoptosis and extracellular matrix (ECM) degradation. Previous studies have shown that moderate autophagy has a protective effect against apoptosis in NP cells. Berberine (BBR) is an alkaloid compound with many beneficial properties including antimicrobial, anti-inflammatory, antioxidative, and anti-apoptotic activity. Recently, it was found to induce autophagy in various tissues as well. Thus, we hypothesized that BBR may exert a therapeutic effect on IVDD through autophagy activation. In this study, we investigated the effects of BBR on IVDD and delineated a potential mechanism. BBR treatment in vitro inhibited the expression of pro-apoptotic proteins induced by tert-butyl hydroperoxide (TBHP), and increased the expression of anti-apoptotic Bcl-2. Furthermore, it prevented ECM degradation by inhibiting the production of matrix-degrading enzymes. Additionally, BBR treatment significantly activated autophagy in NP cells. However, autophagy inhibition markedly suppressed BBRs effects on NP cell apoptosis and ECM degeneration, indicating that autophagy activation with BBR treatment is protective against IVDD. In vivo, BBR treatment increased the expression of LC3 in disc cells and prevented the development of IVDD in a needle puncture-induced rat model. Thus, BBR stimulates autophagy as a protective mechanism against NP cell apoptosis and ECM degeneration, revealing its therapeutic potential in the treatment of IVDD.

Asperosaponin VI promotes angiogenesis and accelerates wound healing in rats via up-regulating HIF-1α/VEGF signaling

Wound therapy remains a clinical challenge due to the complexity of healing pathology and high demand of achieving functional and aesthetically satisfactory scars. Newly formed blood vessels are essential for tissue repair since they can support cells at the wound site with nutrition and oxygen. In this study, we investigated the effects of Asperosaponin VI (ASA VI) isolated from a traditional Chinese medicine, the root of Dipsacus asper Wall, in promoting angiogenesis, as well as its function in wound therapeutics. Treatment of human umbilical vein endothelial cells (HUVECs) with ASA VI (20–80 μg/mL) dose-dependently promoted the proliferation, migration and enhanced their angiogenic ability in vitro, which were associated with the up-regulated HIF-1α/VEGF signaling. Full-thickness cutaneous wound model rats were injected with ASA VI (20 mg·kg−1·d−1, iv) for 21 d. Administration of ASA VI significantly promoted the cutaneous wound healing, and more blood vessels were observed in the regenerated tissue. Due to rapid vascularization, the cellular proliferation status, granulation tissue formation, collagen matrix deposition and remodeling processes were all accelerated, resulting in efficient wound healing. In summary, ASA VI promotes angiogenesis of HUVECs in vitro via up-regulating the HIF-1α/VEGF pathway, and efficiently enhances the vascularization in regenerated tissue and facilitates wound healing in vivo. The results reveal that ASA VI is a potential therapeutic for vessel injury-related wounds.

Risk Factor of Failed Reduction of Posterior Ligamentatoxis Reduction Instrumentation in Managing Thoracolumbar Burst Fractures: A Retrospective Study

OBJECTIVEnTo determine whether radiographic findings associated with thoracolumbar burst fractures could be predictors of failure of short-segment posterior instrumentation with insertion screw at the fracture level (SSPI-f).nnnMETHODSnSeventy-five patients with thoracolumbar burst fracture surgically treated by SSPI-f were enrolled in the study and divided into 2 groups: a reduction group (nxa0=xa046) and a failed-reduction group (nxa0= 29). Radiographic data including local kyphosis, Cobb angle, anterior vertebral height, posterior vertebral height (PVH), anterior/posterior vertebral height ratio, interpedicle distance (IPD), bony compress area, bony fracture area, and compress-fracture area of the fractured vertebra and clinical data including age and neurologic function were also analyzed. t test, Pearson χ2 test, and binary logistic regression were performed to compare the values.nnnRESULTSnThe PVH in the failed-reduction group was smaller than that of the reduction group (83.5% ± 7.2% and 89.1% ± 5.4%, respectively) (Pxa0= 0.001). The IPD differed between the reduction and failed-reduction group (18.0% ± 4.1% and 25.8% ± 7.1%, respectively) (P < 0.001). There was a statistical difference between the 2 groups in delayed time before surgery (Pxa0= 0.008). There was a significant difference of bony fracture area and compress-fracture area of the fractured vertebra between the failed-reduction and reduction group (both P < 0.001). Binary logistic regression showed that IPD was a risk factor of reduction failure of SSPI-f (Pxa0= 0.001).nnnCONCLUSIONSnThese results showed that increased IPD was a risk factor of failed-reduction of SSPI-f in managing thoracolumbar burst fractures, particularly for patients with neurologic deficit, whereas local kyphosis, Cobb angle, anterior vertebral height, PVH, anterior/posterior vertebral height ratio, bony compress area, bony fracture area, and compress-fracture area of the fractured vertebra were not.

Melatonin protects vertebral endplate chondrocytes against apoptosis and calcification via the Sirt1-autophagy pathway

Melatonin is reportedly associated with intervertebral disc degeneration (IDD). Endplate cartilage is vitally important to intervertebral discs in physiological and pathological conditions. However, the effects and mechanism of melatonin on endplate chondrocytes (EPCs) are still unclear. Herein, we studied the effects of melatonin on EPC apoptosis and calcification and elucidated the underlying mechanism. Our study revealed that melatonin treatment decreases the incidence of apoptosis and inhibits EPC calcification in a dose‐dependent manner. We also found that melatonin upregulates Sirt1 expression and activity and promotes autophagy in EPCs. Autophagy inhibition by 3‐methyladenine reversed the protective effect of melatonin on apoptosis and calcification, while the Sirt1 inhibitor EX‐527 suppressed melatonin‐induced autophagy and the protective effects of melatonin against apoptosis and calcification, indicating that the beneficial effects of melatonin in EPCs are mediated through the Sirt1‐autophagy pathway. Furthermore, melatonin may ameliorate IDD in vivo in rats. Collectively, this study revealed that melatonin reduces EPC apoptosis and calcification and that the underlying mechanism may be related to Sirt1‐autophagy pathway regulation, which may help us better understand the association between melatonin and IDD.

Parkin-mediated mitophagy as a potential therapeutic target for intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a complicated pathological condition blamed for low back pain. Mitochondrion is of vital importance for cellular homeostasis, and mitochondrial dysfunction is considered to be one of the major causes of cellular damage. Mitophagy is a cellular process to eliminate impaired mitochondria and showed protective effects in various diseases; however, its role in IDD is still not clear. Here, we explore the role of Parkin-mediated mitophagy in IDD. In this study, we found that Parkin was upregulated in degenerative nucleus pulposus (NP) tissues in vivo as well as in TNF-α stimulated NP cells in vitro. Knockdown of Parkin by siRNA showed that Parkin is crucial for apoptosis and mitochondrion homeostasis in NP cells. Further study showed that upregulation of Parkin by salidroside may eliminate impaired mitochondria and promote the survival of NP cells through activation of mitophagy in vitro. In in vivo study, we found that salidroside could inhibit the apoptosis of NP cells and ameliorate the progression of IDD. These results suggested that Parkin is involved in the pathogenesis of IDD and may be a potential therapeutic target for IDD.