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Background: Osteochondral fracture (OCF) is one of the severe complications following a patellar dislocation. The appropriate fixation method for patients with OCF remains controversial. Methods: Eighteen patients who had undergone surgery after a patellar dislocation were recruited retrospectively. Patellar OCF was fixed with an absorbable suture in an unreported method. The medial patellofemoral ligament (MPFL) was repaired or reconstructed if necessary. The Lysholm and Kujala knee scoring systems were used to evaluate the knee function. Imaging examinations were used to confirm the fracture healing. Results: The mean period of follow-up was 36 months. All patients recovered well postoperatively without symptomatic complications. The Lysholm score and the Kujala score improved significantly from 37.6 (SD =6.8) and 45.9 (SD =6.4) preoperatively to 80.9 (SD =7.4) and 89.4 (SD =6.8) postoperatively at the latest followup, respectively. Imaging evidence including X-ray and MRI revealed good healing of the OCFs. Conclusions: This study showed satisfactory mid-term outcomes of OCF fixation using absorbable suture, which supports this method's potential to be a novel surgical method in the treatment of patellar OCF caused by a patellar dislocation.

Osteosarcoma (OS) is the primary malignant bone tumor with a peak incidence in children and adolescents. However, the little molecular mechanism of pathogenesis has been known and it is urgent to develop new therapeutical strategies to improve outcomes for patients. CDDO-NFM (N-formylmorpholine substituent of CDDO) is a newly synthesized triterpenoid, which is a derivative of oleanolic acid. In this study, we explored whether CDDO-NFM possesses a potential antitumor effect and revealed its molecular mechanism. We found that CDDO-NFM efficiently inhibited cell growth of OS cells and this inhibitory effect was independent of apoptosis-related and cell-cycle-related proteins.CDDO-NFM could decrease the level of glucose uptake, the generation of lactate, and the production of adenosine triphosphate to block the process of glycolysis. In vitro and in vivo cell-based assays showed that CDDO-NFM inhibited glycolysis via degradation of c-MYC rather than activating peroxisome proliferator-activated receptor gamma. Finally, CDDO-NFM could reduce tumor volume and weight with low toxicity, and down-regulate the expression of glycolysis-related enzymes in nude mice. Taken together, these results showed that CDDO-NFM might be a promising antitumor compound. K E Y W O R D S CDDO-NFM, c-MYC, glycolysis, osteosarcoma J Cell Biochem. 2019;120:9264-9276. wileyonlinelibrary.com/journal/jcb 9264 |

Background/Aims: Periodic mechanical stress can promote chondrocyte proliferation and matrix synthesis to improve the quality of tissue-engineered cartilage. Although the integrin β1–ERK1/2 signal cascade has been implicated in periodic mechanical stress-induced mitogenic effects in chondrocytes, the precise mechanisms have not been fully established. The current study was designed to probe the roles of CaMKII and Pyk2 signaling in periodic mechanical stress-mediated chondrocyte proliferation and matrix synthesis. Methods: Chondrocytes were subjected to periodic mechanical stress, proliferation was assessed by direct cell counting and CCK-8 assay; gene expressions were analyzed using quantitative real-time PCR, protein abundance by Western blotting. Results: Mechanical stress, markedly enhanced the phosphorylation levels of Pyk2 at Tyr⁴⁰² and CaMKII at Thr²⁸⁶. Both suppression of Pyk2 with Pyk2 inhibitor PF431396 or Pyk2 shRNA and suppression of CaMKII with CaMKII inhibitor KN-93 or CaMKII shRNA blocked periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. Additionally, either pretreatment with KN-93 or shRNA targeted to CaMKII prevented the activation of ERK1/2 and Pyk2 under conditions of periodic mechanical stress. Interestingly, in relation to periodic mechanical stress, in the context of Pyk2 inhibition with PF431396 or its targeted shRNA, only the phosphorylation levels of ERK1/2 were abrogated, while CaMKII signal activation was not affected. Moreover, the phosphorylation levels of CaMKII- Thr²⁸⁶ and Pyk2- Tyr⁴⁰² were abolished after pretreatment with blocking antibody against integrinβ1 exposed to periodic mechanical stress. Conclusion: Our results collectively indicate that periodic mechanical stress promotes chondrocyte proliferation and matrix synthesis through the integrinβ1–CaMKII–Pyk2–ERK1/2 signaling cascade.

In recent years, a variety of studies have been performed to investigate the cellular responses of periodic mechanical stress on chondrocytes. Integrin β1-mediated ERK1/2 activation was proven to be indispensable in periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. However, other signal proteins responsible for the mitogenesis of chondrocytes under periodic mechanical stress remain incompletely understood. In the current investigation, we probed the roles of integrin-linked kinase (ILK) signaling in periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. We found that upon periodic mechanical stress induction, ILK activity increased significantly. Depletion of ILK with targeted shRNA strongly inhibited periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis. In addition, pretreatment with a blocking antibody against integrin β1 resulted in a remarkable decrease in ILK activity in cells exposed to periodic mechanical stress. Furthermore, inhibition of ILK with its target shRNA significantly suppressed ERK1/2 activation in relation to periodic mechanical stress. Based on the above results, we identified ILK as a crucial regulator involved in the integrin β1-ERK1/2 signal cascade responsible for periodic mechanical stress-induced chondrocyte proliferation and matrix synthesis.

Background: Patients with unstable os acromiale often complain of shoulder pain. Numerous surgical treatment options have been introduced with inconsistent clinical results. In this study, a novel surgical treatment using polyester sutures to fix unstable os acromiale was introduced, and clinical results were reported.Methods: We retrospectively studied 10 shoulders that were diagnosed with os acromiale from January 2014 to January 2016. All 10 cases were of the meso-acromion type. Except for the first case in our series, cases of os acromiale were fixed using polyester sutures arthroscopically. The standardized scores and visual analog scale (VAS) were recorded preoperatively and at each follow-up. A computed tomography (CT) scan was ordered at the follow-up of 12 months. Results:The average follow-up length was 28.7 months, ranging from 26 to 33 months. The average Constant score before surgery was 40.50±4.53 points, which significantly improved to 75.60±5.17 points after surgery. The average VAS score was reduced from 5.20±1.14 points to 1.60±0.84. At the follow-up of 12 months, a CT scan was ordered. All the patients showed a bony union of the os acromiale. On the CT scan, two small pits could be seen on the medial and lateral side of the acromion, which indicated the level of the os acromiale. The position of the os acromiale was good, and no evident sclerosis was found on the edges of the fragments.Conclusions: Polyester sutures could provide reliable strength for the fixation of os acromiale without any irritation from hardware.

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The osteoarthritis caused by trauma or inflammation is associated with severe patient morbidity and economic burden. Accumulating studies are focusing on the repair of articular cartilage defects by constructing tissue-engineered cartilage. Recent evidence suggests that optimizing the source and quality of seed cells is one of the key points of cartilage tissue engineering. In this study, we demonstrated that Kindlin-2 and its activated PI3K/AKT signaling played an essential role in promoting extracellular matrix (ECM) secretion and ameliorating IL-1beta-induced inflammation in chondrocytes cocultured with bone marrow stem cells (BMSCs). In vivo experiments revealed that coculture significantly promoted hyaline cartilage regeneration. In vitro studies further uncovered that chondrocytes cocultured with BMSCs in the direct contact coculture system upregulated Kindlin-2 expression and subsequently activated the PI3K/AKT signaling pathway, which not only increases Sox9 and Col2 expression but also restores mitochondrial membrane potential and reduces ROS levels and apoptosis under inflammatory conditions. Overall, our findings indicated that direct contact BMSC-chondrocyte coculture system could promote chondrogenesis, and identified Kindlin-2 represents a key regulator in this process.