TRIM54 alleviates inflammation and apoptosis by stabilizing YOD1 in rat tendon-derived stem cells.

Tendinopathy is a disorder of musculoskeletal system that primarily affects athletes and the elderly. Current treatment options are generally comprised of various exercise and loading programs, therapeutic modalities, and surgical interventions and are limited to pain management. This study is to understand the role of TRIM54 (tripartite motif containing 54) in tendonitis through in vitro modeling with tendon-derived stem cells (TDSCs) and in vivo using rat tendon injury model. Initially, we observed that TRIM54 overexpression in TDSCs model increased stemness and decreased apoptosis. Additionally, it rescued cells from tumor necrosis factor α-induced inflammation, migration, and tenogenic differentiation. Further, through immunoprecipitation studies, we identified that TRIM54 regulates inflammation in TDSCs by binding to and ubiquitinating YOD1. Further, overexpression of TRIM54 improved the histopathological score of tendon injury as well as the failure load, stiffness, and young modulus in vivo. These results indicated that TRIM54 played a critical role in reducing the effects of tendon injury. Consequently, these results shed light on potential therapeutic alternatives for treating tendinopathy.

PKD1 alleviates oxidative stress-inhibited osteogenesis of rat bone marrow-derived mesenchymal stem cells through TAZ activation.

Oxidative stress is known to inhibit osteogenesis and PKD1 is implicated in bone remodeling and skeletogenesis. In the present study, we explored the role of PKD1 in osteogenesis under oxidative stress. H2 O2 was used to induce oxidative stress in rat bone marrow (BM)-mesenchymal stem cells (MSCs) during osteoblast differentiation. Alkaline phosphatase (ALP) activity, calcium deposits, and the RUNX2 marker were assayed to determine osteogenic differentiation. The correlation of PKD1, Sirt1, c-MYC, and TAZ was further confirmed by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay. We found that H2 O2 induced the downregulation of PKD1 expression and the upregulation of c-MYC, and Sirt1 was accompanied by decreasing cell viability in BM-MSCs. During osteogenic differentiation, the expression of PKD1 was upregulated significantly whereas Sirt1 tended to be upregulated mildly under normal conditions. Both PKD1 and Sirt1 were upregulated upon oxidative stress. The positive correlation of PKD1 expression with osteogenic differentiation under normal conditions might be hindered by oxidative stress and PKD1 could interact with TAZ under oxidative stress to regulate osteogenic differentiation. Our results suggest that PKD1 may alleviate oxidative stress-inhibited osteogenesis of rat BM-MSCs through TAZ activation.

Burn-induced heterotopic ossification from incidence to therapy: key signaling pathways underlying ectopic bone formation.

Burn injury is one of the potential causes of heterotopic ossification (HO), which is a rare but debilitating condition. The incidence ranges from 3.5 to 5.6 depending on body area. Burns that cover a larger percentage of the total body surface area (TBSA), require skin graft surgeries, or necessitate pulmonary intensive care are well-researched risk factors for HO. Since burns initiate such complex pathophysiological processes with a variety of molecular signal changes, it is essential to focus on HO in the specific context of burn injury to define best practices for its treatment. There are numerous key players in the pathways of burn-induced HO, including neutrophils, monocytes, transforming growth factor-ß1-expressing macrophages and the adaptive immune system. The increased inflammation associated with burn injuries is also associated with pathway activation. Neurological and calcium-related contributions are also known. Endothelial-to-mesenchymal transition (EMT) and vascularization are known to play key roles in burn-induced HO, with hypoxia-inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF) as potential initiators. Currently, non-steroidal anti-inflammatory drugs (NSAIDs) and radiotherapy are effective prophylaxes for HO. Limited joint motion, ankylosis and intolerable pain caused by burn-induced HO can be effectively tackled via surgery. Effective biomarkers for monitoring burn-induced HO occurrence and bio-prophylactic and bio-therapeutic strategies should be actively developed in the future.

Nudt21-mediated alternative polyadenylation of HMGA2 3'-UTR impairs stemness of human tendon stem cell.

Tendon-derived stem cells (TSCs) play a primary role in tendon physiology, pathology, as well as tendon repair and regeneration after injury. TSCs are often exposed to mechanical loading-related cellular stresses such as oxidative stress, resulting in loss of stemness and multipotent differentiation potential. Cytoprotective autophagy has previously been identified as an important mechanism to protect human TSCs (hTSCs) from oxidative stress induced impairments. In this study, we found that high-mobility AT-hook 2 (HMGA2) overexpression protects hTSCs against H2O2-induced loss of stemness through autophagy activation. Evidentially, H2O2 treatment increases the expression of Nudt21, a protein critical to polyadenylation site selection in alternative polyadenylation (APA) of mRNA transcripts. This leads to increased cleavage and polyadenylation of HMGA2 3'-UTR at the distal site, resulting in increased HMGA2 silencing by the microRNA let-7 and reduced HMGA2 expression. In conclusion, Nudt21-regulated APA of HMGA2 3'-UTR and subsequent HMGA2 downregulation mediates oxidative stress induced hTSC impairments.

Treatment of Diabetic Foot with Autologous Stem Cells: A Meta-Analysis of Randomized Studies.

BACKGROUND: This meta-analysis was to evaluate the efficacy of autologous stem cell administration for the treatment of diabetic foot. METHODS: The electronic databases included PubMed, EMBASE, BIOSIS, Cochrane central, and Google Scholar internet, last updated on May 30, 2019. Evaluated outcomes included the rate of wound healing and amputation. Dichotomous outcomes were described as risk ratios (RR) with 95% confidence intervals (CIs). Statistical analysis was performed with RevMan 5.0 software and STATA 10.0 software. RESULTS: Eight randomized controlled trial (RCT) studies were included in this study. The meta-analysis showed a lower amputation (RR 0.25, 95% CI 0.11 to 0.54, I 2 = 0) and a higher wound healing rate (RR 2.05, 95% CI 1.67 to 2.51, I 2 = 4) in the cell therapy group compared with control. CONCLUSION: This meta-analysis supports the effective role of stem cell therapy in promoting wound healing and decreasing rate of amputation in diabetic foot. In the future, more high quality and well-designed studies are need.

Autologous platelet-rich plasma treatment for patients with diabetic foot ulcers: a meta-analysis of randomized studies.

BACKGROUND: This study will explore the effectiveness and safety of autologous PRP in the treatment of patients with DFU. METHODS: The electronic databases of PubMed, EMBASE, BIOSIS, Cochrane central, and Google Scholar internet were searched updated on Jan 30, 2020. Evaluated outcomes included rate of complete ulcer healing, time to healing and adverse events. Statistical analysis was performed with RevMan 5.0 software and STATA 10.0 software. RESULTS: Ten RCTs with 456 patients were included in this study. The meta-analysis showed a higher complete ulcer healing rate (RR = 1.32, 95% CI 1.06 to 1.65, P = 0.01, I2 = 57%), a shorter healing time (MD = -23.42, 95% CI -37.33 to -9.51, P = 0.01, I2 = 78%), with no increasing the incidence of adverse events (RR = 0.48, 95% CI 0.22 to 1.05, P = 0.75, I2 = 0%) in PRP group compared with control. Mixed evidence was seen for publication bias, but analyses by using the trim-and-fill method did not appreciably alter results. CONCLUSION: Our findings suggest that autologous PRP may improve the complete ulcer healing rate, shorten the healing time, with no increasing the incidence of adverse events.

Assessment of the Risk Factors of Multidrug-Resistant Organism Infection in Adults With Type 1 or Type 2 Diabetes and Diabetic Foot Ulcer.

OBJECTIVES: To our knowledge, this is the first review to analyze the literature identifying risk factors for multidrug-resistant organism (MDRO) infection in patients with diabetic foot ulcer. The purpose of this study was to collect the currently published data to determine the most commonly and consistently identified risk factors for MDRO infection. METHODS: PubMed, MEDLINE, BIOSIS, Web of Science and the Cochrane Library electronic databases were searched. The last search updated was in September 2019. The evaluated outcomes included age, male sex, type of diabetes, diabetes duration, level of glycated hemoglobin, ulcer type, wound duration, ulcer size, ulcer grade, osteomyelitis, previous antibiotic therapy and previous hospitalization. The standard mean difference or the odds ratio (OR) was calculated for continuous or dichotomous data, respectively. The quality of the studies was assessed, and meta-analyses were performed with Cochrane Collaboration's RevMan 5.0 software. RESULTS: A total of 11 studies, including 1,229 patients provided evidence for 6 possible risk factors for MDRO infection. Ischemic ulcer (OR, 0.50; 95% confidence interval [CI], 0.35 to 0.71), ulcer size (standard mean difference, -0.27; 95% CI, -0.46 to -0.08), ulcer grade (OR, 0.36; 95% CI, 0.15 to 0.83), osteomyelitis (OR, 0.33; 95% CI, 0.25 to 0.45), previous antibiotic therapy (OR, 0.08; 95% CI, 0.04 to 0.14) and previous hospitalization (OR, 0.15; 95% CI, 0.08 to 0.28) were identified as risk factors for MDRO infection in patients with diabetic foot ulcer. CONCLUSIONS: Our meta-analysis indicated that ischemic ulcer, ulcer size, ulcer grade, osteomyelitis, previous antibiotic therapy and previous hospitalization were associated with MDRO infection in patients with diabetic foot ulcer.

Early hybrid nonbridging external fixation of unstable distal radius fractures in patients aged ≥50 years.

OBJECTIVE: We evaluated hybrid nonbridging external fixation (NBEF) supplemented by K-wires as an effective and safe treatment option for osteoporotic distal radius fractures (DRFs) in a retrospective case series. METHODS: Sixteen extra-articular and one intra-articular DRF were treated by NBEF from 2016 to 2018 (mean patient age, 61.8 years; 15 women, 1 man). Radiographic parameters (volar tilt, radial inclination, and ulnar variance), range of motion, grip power, the visual analog scale score, and the Disabilities of the Arm, Shoulder and Hand (DASH) score were assessed at 4 weeks, 6 weeks, 6 months, and 12 months postoperatively. RESULTS: The volar tilt and radial inclination were restored after surgery and maintained well. The mean visual analog scale score was 4 ± 1 at 4 weeks. Range of motion was restored to 79% to 91% at 6 weeks. The DASH score was good before NBEF device removal. Two superficial pin-tract infections were easily treated with antibiotics. CONCLUSIONS: Hybrid NBEF transfixes DRFs in a multiplanar fashion, and augmentation with percutaneous K-wires provides direct fixation in radial shift and withstands axial loads in fracture fragments. It allows early mobilization with rigid fixation. Hybrid NBEF is reliable for unstable extra-articular and simple intra-articular DRFs in older patients. CLINICAL STUDY REGISTRATION NUMBER: ChiCTR1900021712.

Rapamycin Attenuates High Glucose-Induced Inflammation Through Modulation of mTOR/NF-κB Pathways in Macrophages.

Background: The NLRP3 inflammasome is one of the key contributors to impaired wound healing in diabetes. In this study, we assessed the role of rapamycin on high glucose-induced inflammation in THP-1-derived macrophages and investigated the underlying signaling mechanisms. Methods: THP-1-derived macrophages were treated with high glucose to induce NLRP3 inflammasome activation. The cells were pretreated with rapamycin, BAY 11-7082, or PDTC before exposure to HG. mTOR, NF-κB, and NLRP3 inflammasome expression were measured by western blotting. Results: We found that rapamycin reduced NLRP3 inflammasome activation in macrophages. Rapamycin reduced NLRP3 inflammasome activation by inhibiting mTOR phosphorylation and NF-κB activation. Moreover, mTOR siRNA inhibited NF-κB activation, leading to the suppression of NLRP3 inflammasome activation. Conclusion: Rapamycin can ameliorate high glucose-induced NLRP3 inflammasome activation by attenuating the mTOR/NF-κB signaling pathway in macrophages. Rapamycin may act as a possible therapeutic option for high glucose-induced inflammatory response in impaired wound healing in the future.

Vitamin D and diabetic foot ulcer: a systematic review and meta-analysis.

We aimed to evaluate the association between vitamin D deficiency and diabetic foot ulcer (DFU) in patients with diabetes. Pubmed, EMBASE, BIOSIS, the Cochrane Library, and Web of Knowledge, last updated in July 2018, were searched. We assessed eligible studies for the association between vitamin D deficiency and DFU in diabetic patients. The mean difference (MD) or the odds ratio (OR) was calculated for continuous or dichotomous data respectively. Data were analyzed by using the Cochrane Collaboration's RevMan 5.0 software. Seven studies that involved 1115 patients were included in this study. There were significantly reduced vitamin D levels in DFU (MD -13.47 nmol/L, 95%CI -16.84 to -10.10; P = 0.34, I2 = 12%). Severe vitamin D deficiency was significantly associated with an increased risk of DFU (OR 3.22, 95%CI 2.42-4.28; P = 0.64, I2 = 0%). This is the first meta-analysis demonstrating the association between serum vitamin D levels and DFU. Severe vitamin D deficiency is significantly associated with an increased risk of DFU.

Histone methyltransferase SETD2 regulates osteosarcoma cell growth and chemosensitivity by suppressing Wnt/ß-catenin signaling.

SETD2 is a histone methyltransferase that catalyzes the trimethylation of lysine 36 on histone 3. SETD2 is frequently found to be mutated or deleted in a variety of human tumors, whereas the role of SETD2 in oncogenesis of osteosarcoma has never been defined. Here in our study, we uncovered that SETD2 regulates tumor growth and chemosensitivity of osteosarcoma. Overexpression of SETD2 significantly inhibited osteosarcoma cell growth in vitro and in vivo. Moreover, SETD2 significantly enhanced cisplatin-induced apoptosis in osteosarcoma cells and inhibited cancer stem cell properties in OS cells. SETD2 regulates Wnt/ß-catenin signaling and its downstream gene c-myc, CD133 and cyclin D1. We further revealed that SETD2 upregulates H3K36me3 modification in GSK3B loci and promotes its transcription, which lead to ß-catenin degradation. Together, our study delineates SETD2 function in osteosarcoma as an important regulator of Wnt/ß-catenin signaling, and suggests SETD2 as a novel target in diagnosis and combined chemotherapy of osteosarcoma.

A systematic review and meta-analysis comparing combined intravenous and topical tranexamic acid with intravenous administration alone in THA.

PURPOSE: To compare the effectiveness and safety of combined intravenous and topical tranexamic acid with intravenous use alone in THA. METHODS: The electronic databases MEDLINE, EMBASE, BIOSIS, Cochrane central, and further adapted for Google and Google Scholar internet, last updated on Dec 30, 2016, were searched. Evaluated outcomes included total blood loss, transfusion rate, maximum postoperative Hb drop, and incidence of thromboembolic complications. The standard mean difference (SMD) or the relative risk (RR) was calculated for continuous or dichotomous data respectively. The quality of the trial was assessed, and meta-analyses were performed with the Cochrane Collaboration's RevMan 5.0 software. RESULTS: Five RCTs with 457 patients were included. Combined TXA administration reduced blood loss (SMD, 1.39; 95%CI, 0.55 to 2.23; P<0.00001, I2 = 94%), hemoglobin decline (SMD, 0.84; 95%CI, 0.13 to 1.54; P = 0.01, I2 = 83%) and the need for transfusion (RR, 2.58; 95%CI, 1.59 to 4.18; P = 0.65, I2 = 0%) without increasing the rate of thromboembolic complications significantly (RR, 0.83; 95%CI, 0.27 to 2.54; P = 0.81, I2 = 0%). CONCLUSION: The present study has emphasized that combined TXA administration can effectively reduce blood loss, hemoglobin decline and the need for transfusion without increasing the rate of thromboembolic complications.

Toe-to-finger combined with free flap transfer for primary one-stage post-traumatic reconstruction of the complex fingerless hand.

Toe-to-finger transplantation is intimately related to the development of microsurgical free tissue transplantation, which is one of the most important advances in the history of reconstructive surgery. It is also generally acknowledged that a mangled hand with massive tissue loss and amputation of multiple digits presents a challenge for plastic and reconstructive surgeons. In this retrospective study we reviewed 11 cases of primary one-stage post-traumatic reconstruction of complex fingerless hands using a combination of toe-to-finger and free tissue transplantation performed in Shanghai Jiao Tong University affiliated Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine affiliated Ninth People's Hospital from January 2001 to November 2014. Primary healing was achieved in 10 cases, while in the other case partial flap loss was documented and secondary healing was achieved by skin grafting. We concluded from this study that, by selecting suitable patients, use of a combination of toe-to-finger and free tissue transplantation may provide an alternative option for mangled hand salvage with satisfactory functional and esthetic results.

Autophagy Prevents Oxidative Stress-Induced Loss of Self-Renewal Capacity and Stemness in Human Tendon Stem Cells by Reducing ROS Accumulation.

BACKGROUND/AIMS: Tendon stem cells (TSCs) exhibit a high self-renewal capacity, multi-differentiation potential, and low immunogenicity; thus, these cells might provide a new cell source for tendon repair and regeneration. TSCs are exposed to increased oxidative stress at tendon injury sites; however, how TSCs maintain their stemness under oxidative stress is not clear. METHODS AND RESULTS: In this study, we found that H2O2 treatment increased ROS accumulation in human TSCs (hTSCs) and resulted in loss of self-renewal capacity and stemness, as reflected in reduced colony formation and proliferation, decreased expression of the stemness markers Nanog, Oct-4, NS, and SSEA-4, and impaired differentiation capability. These H2O2-induced damages were prevented by pretreatment with starvation or rapamycin. Pretreatment with starvation or rapamycin prior to H2O2 exposure also led to decreased intracellular and mitochondrial ROS accumulation along with increased autophagic activity, as manifested in increased LC3 cleavage, Beclin-1 expression, and GFP-LC3-labeled autophagosome formation. Autophagy inhibition by 3-MA or CQ, or by shRNA silencing of Agt-7 or Beclin-1 reduced the protective effects of starvation and rapamycin on H2O2-treated hTSCs. CONCLUSION: Thus, the findings of this study suggest that autophagy prevents oxidative stress-induced loss of self-renewal capacity and stemness in hTSCs through suppression of ROS accumulation.

MiR-24-BIM-Smac/DIABLO axis controls the sensitivity to doxorubicin treatment in osteosarcoma.

Emerging evidence shows that microRNAs (miRNAs) act as critical regulators in the progression and chemoresistance of multiple tumors, including osteosarcoma (OS). In this study, we found that the level of miR-24 was increased in OS patients' serum, tumor tissues and OS cell lines. Furthermore, we found that knockdown of miR-24 by its specific inhibitors significantly increased the therapeutic effect of doxorubicin (DOX) on OS cell lines (MG-63 and HOS). Moreover, miR-24 inhibitors resensitized the doxorubicin-resistant MG-63 cells (MG-63/R) and HOS cells (HOS/R) to DOX. As the gene of Bcl-2 interacting mediator of cell death (BIM) was proved to be a target of miR-24 in MG-63/R cells, we further observed that the miR-24 inhibitors promoted the DOX-induced apoptosis via mitochondrial pathway. In addition, results of immunoprecipitation showed the release of second mitochondria derived activator of caspase/ direct IAP binding protein with low pI (Smac/DIABLO) abolished the biological activity of X-linked inhibitor of apoptosis protein (XIAP) by binding with it, which subsequently induced the activation of caspase 9, 7 and 3. In summary, those results strongly suggest that the miR-24-BIM-Smac/DIABLO axis might be a novel target for the treatment of OS.

TGIF1 Gene Silencing in Tendon-Derived Stem Cells Improves the Tendon-to-Bone Insertion Site Regeneration.

BACKGROUND/AIMS: The slow healing process of tendon-to-bone junctions can be accelerated via implanted tendon-derived stem cells (TDSCs) with silenced transforming growth interacting factor 1 (TGIF1) gene. Tendon-to-bone insertion site is the special form of connective tissues derivatives of common connective progenitors, where TGF-ß plays bidirectional effects (chondrogenic or fibrogenic) through different signaling pathways at different stages. A recent study revealed that TGF-ß directly induces the chondrogenic gene Sox9. However, TGIF1 represses the expression of the cartilage master Sox9 gene and changes its expression rate against the fibrogenesis gene Scleraxis (Scx). METHODS: TGIF1 siRNA was transduced or TGIF1 was over-expressed in tendon-derived stem cells. Following suprapinatus tendon repair, rats were either treated with transduced TDSCs or nontransduced TDSCs. Histologic examination and Western blot were performed in both groups. RESULTS: In this study, the silencing of TGIF1 significantly upregulated the chondrogenic genes and markers. Similarly, TGIF1 inhibited TDSC differentiation into cartilage via interactions with TGF-ß-activated Smad2 and suppressed the phosphorylation of Smad2. The area of fibrocartilage at the tendon-bone interface was significantly increased in the TGIF1 (-) group compared with the control and TGIF1-overexpressing groups in the early stages of the animal model. The interface between the tendon and bone showed a increase of new bone and fibrocartilage in the TGIF1 (-) group at 4 weeks. Fibrovascular scar tissue was observed in the TGIF1-overexpressing group and the fibrin glue only group. Low levels of fibrocartilage and fibrovascular scar tissue were found in the TDSCs group. CONCLUSION: Collectively, this study shows that the tendon-derived stem cell modified with TGIF1 gene silencing has promising effects on tendon-to-bone healing which can be further explored as a therapeutic tool in regenerative medicine.

Bone Morphogenetic Protein for the Healing of Tibial Fracture: A Meta-Analysis of Randomized Controlled Trials.

PURPOSE: To review the evidence from RCTs on clinical outcomes and benefit of acute tibial fracture and nonunion treated with and without BMPs. MATERIAL: We searched multiple databases (MEDLINE, EMABSE, BIOSIS and Cochrane central) as well as reference lists of articles and contacted authors. Evaluated outcomes included union rate, revision rate, hardware failure and infection. The weighted and standard mean difference (WMD and SMD) or the relative risk (RR) was calculated for continuous or dichotomous data respectively. The quality of the trial was assessed, and meta-analyses were performed with the Cochrane Collaboration's REVMAN 5.0 software. RESULTS: Eight RCTs involving 1113 patients were included. For acute tibial fracture, BMP group was associated with a higher rate of union (RR, 1.16; 95% CI, 1.04 to 1.30) and a lower rate of revision (RR, 0.68; 95% CI, 0.54 to 0.85) compared with control group. No significant differences were found in rate of hardware failure and infection. The pooled RR for achieving union for tibial fracture nonunion was 0.98 (95% CI, 0.86 to 1.13). There was no significant difference between the two groups in the rate of revision (RR, 0.48; 95% CI, 0.13 to 1.85) and infection (RR, 0.61; 95% CI, 0.37 to 1.02). CONCLUSION: Study on acute tibial fractures suggests that BMP is more effective that controls, for bone union and for decreasing the rate of surgical revision to achieve union. For the treatment of tibial fracture nonunion, BMP leads to similar results to as autogenous bone grafting. Finally, well-designed RCTs of BMP for tibial fracture treatment are also needed.

Notoginsenoside R1 stimulates osteogenic function in primary osteoblasts via estrogen receptor signaling.

Notoginsenoside R1 (NGR1), a novel phytoestrogen isolated from Panax notoginseng, has been widely used in the treatment of microcirculatory diseases in Asian countries. Here we investigated the effect of NGR1 on osteoblast differentiation and mineralization process. Furthermore, we also evaluated NGR1's estrogenic properties, especially its effects on estrogen receptors (ERs). NGR1 activated the transcriptional activity of phosphorylated estrogen response element (pERE)-luciferase (Luc) and induced ERα phosphorylation in hBMSC. In addition, ER activation correlated with induction and was associated with osteoblast differentiation biomarkers including alkaline phosphatase activity and transcription of osteoblastic genes, e.g., type I collagen (COL1), osteonectin, osteocalcin (OC), runt related protein 2 (Runx2), and osterix. NGR1 also promoted the mineralization process of osteoblasts. The NGR1-induced effects were confirmed to be mediated by the ER by the observation that pretreatment of the osteoblasts with the ER antagonist, ICI 182,780 fully blocked the effects. Our results showed that NGR1 stimulates osteogenic differentiation of cultured osteoblasts by activating ER signaling and in turn might be a potential therapeutic alternative for the prevention and treatment of osteoporosis.

Cell cycle arrest and apoptosis induced by aspidin PB through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells.

Aspidin PB is a natural product extracted from Dryopteris fragrans (L.) Schott, which has been characterized for its various biological activities. We reported that aspidin PB induced cell cycle arrest and apoptosis through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells. Aspidin PB inhibited the proliferation of Saos-2, U2OS, and HOS cells in a dose-dependent and time-dependent manner. Aspidin PB induced changes in the cell cycle regulators (cyclin A, pRb, CDK2, p53, and p21), which caused cell cycle arrest in the S phase. We also explored the role of siRNA targeted to p53; it led to a dose-dependent attenuation of aspidin PB-induced apoptosis signaling. Moreover, after treatment with aspidin PB, the p21-silenced cells decreased significantly at the S phase. Aspidin PB increased the percentage of cells with mitochondrial membrane potential disruption. Western blot analysis showed that aspidin PB inhibited Bcl-2 expression and induced Bax expression to disintegrate the outer mitochondrial membrane and caused cytochrome C release. Mitochondrial cytochrome C release was associated with the activation of caspase-9 and caspase-3 cascades. Furthermore, the double-stranded DNA breaks and reactive oxygen species signaling were both involved in aspidin PB-induced DNA damage. In addition, aspidin PB inhibited tumor growth significantly in U2OS xenografts. Above all, we conclude that aspidin PB represents a valuable natural source and may potentially be applicable in osteosarcoma therapy.