Zhao, Gongyin

Background: Tendon-bone healing after rotator cuff injury is, or remains, a clinical challenge. Purpose: To examine the role of intraoperative use of purified exosome products (PEPs) in the treatment of rotator cuff injuries and to assess the effect of PEP on supraspinatus tendon-bone healing after rotator cuff repair in a rat model. Study Design: Controlled laboratory study. Methods: This study used 120 Sprague-Dawley rats that underwent an acute supraspinatus tendon transection from the insertion, followed by repair using a single transosseous suture. They were divided into 3 groups: a control group that received only sutures, a TISSEEL group that used a commercially available fibrin sealant patch (TISSEEL) of approximately 0.5 cm 2 , and a PEP-TISSEEL group that used a similarly sized TISSEEL patch combined with PEP. Autopsies were performed at 1, 3, 6, and 8 weeks after surgery. Analyses were performed using molecular biological, biomechanical, and histological techniques. Results: At 6 weeks, the PEP-TISSEEL group achieved greater failure load (mean, 27.5 ± 5.3 N) than the control (mean, 16.4 ± 4.2 N; P = .012) and TISSEEL (mean, 23.4 ± 5.0 N; P = .041) groups, with superiority persisting at 12 weeks (27.2 ± 6.5 N vs 13.1 ± 2.6 N [ P = .002] for the control group and 21.1 ± 5.8 N [ P = .037] for the TISSEEL group). DigiGait showed earlier recovery of stride length and paw angle. Histology revealed organized collagen and reduced scarring, while molecular assays demonstrated early inflammatory modulation with subsequent upregulation of collagen type 1 or 3 and TGF-β, supporting accelerated tendon-bone healing. Conclusion: Intraoperative application of PEP-TISSEEL enhanced tendon-bone healing in a rat model by improving biomechanical strength, promoting enthesis-specific histological regeneration, and accelerating functional recovery as evidenced by gait analysis. Clinical Relevance: The intraoperative application of PEP combined with TISSEEL significantly enhances rotator cuff tendon healing by modulating early inflammation, promoting collagen synthesis, and improving biomechanical properties in a rat model. These findings suggest that PEP-based therapies could offer a promising adjunct in surgical repair, potentially reducing retear rates and improving functional outcomes in patients with rotator cuff injuries. Further clinical studies are warranted to translate these benefits into human applications.

Abstract The progression of osteoarthritis (OA) is fundamentally characterized by the aberrant transformation of chondrocytes into a fibrotic phenotype, although the precise molecular mechanisms involved remain inadequately understood. In this study, the interplay between epigenetic modifications and metabolic reprogramming during the activation of fibrocartilage cells in osteoarthritis was investigated. The findings demonstrate that FSTL1 markedly upregulates key glycolytic enzymes, including LDHA, HK2, and PKM, in chondrocytes, triggering a “glycolytic burst” that results in elevated intracellular lactate levels. This accumulated lactate acts as a precursor for epigenetic modifications, specifically promoting the lactylation of histone H3 lysine 18 (H3K18la) in fibrocartilage cells, thereby facilitating the transcriptional activation of critical fibrosis‐related genes such as Itga6, Cxcl10, and Parp16. Notably, pharmacological inhibition of the PI3K/mTOR pathway or lactate dehydrogenase significantly diminishes H3K18la levels and markers of chondrocyte fibrosis, while exogenous lactate supplementation can counteract this effect. In summary, this study unveils the core mechanism by which FSTL1 reshapes the epigenetic landscape of chondrocytes and drives the fibrotic process through the activation of the “glycolysis‐lactate‐H3K18la” cascade axis, offering a dual‐target intervention strategy for OA involving metabolic reprogramming and epigenetic modification.

Abstract Senile osteoporosis (SOP) is a systemic bone disease characterized by increased susceptibility to fractures. In this study, it is found that senescent bone marrow mesenchymal stem cells (BMSCs) exhibit increased sensitivity to ferroptosis, a phenomenon associated with Steap4, a nicotinamide adenine dinucleotide phosphate hydrogen (NADPH)‐dependent metalloreductase that reduces Fe 3+ to Fe 2+ . Therefore, it is aimed to innovatively elucidate how Steap4 affects ferroptosis in senescent BMSCs. These findings indicate that Steap4 promotes intracellular Fe 2+ accumulation and elevates reactive oxygen species (ROS) levels, collectively driving the upregulation of CCAAT/enhancer binding protein beta (C/EBPβ) expression. Interestingly, a functional C/EBPβ binding site is identified within the Steap4 promoter region. Mechanistically, knockdown studies demonstrated that C/EBPβ depletion attenuated Steap4 expression, whereas C/EBPβ overexpression conversely upregulated Steap4 levels. These regulatory processes establish a self‐amplifying Steap4/Fe 2+ ‐ROS/C/EBPβ positive feedback loop. Notably, a large number of adipocytes are also observed in the bone marrow of aged mice. Knockdown of Steap4 and C/EBPβ suppressed the differentiation of BMSCs into adipocytes. Knockdown of Steap4 or deferoxamine (DFO) treatment in animal experiments effectively relieves SOP. In conclusion, Steap4 accelerates the onset of ferroptosis in senescent BMSCs and promotes their differentiation to adipocytes through the Steap4/Fe 2+ ‐ROS/C/EBPβ axis, ultimately impairing their osteogenic capacity.

AimsPrevious studies have highlighted differences in the risk of periprosthetic fractures (PPFs) in patients undergoing total hip arthroplasty with either a cemented taper slip (TS) stem or a composite beam (CB) stem. This biomechanical study explored the occurrence of PPF around these stems, and the protective effect of adding a 16-gauge prophylactic calcar or diaphyseal wire to the TS stems to increase the resistance to torque as a potential way to prevent these fractures.MethodsA total of 21 TS stems (eight alone, six with calcar wiring, and seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard sawbones. The peak torque at failure was measured using a servohydraulic test machine, and the fracture location was recorded. An a priori power analysis determined that seven specimens per group were needed to detect a 30 Nm difference with 90% power, assuming a 14.8 Nm SD in peak torque between groups. Comparisons were performed using paired t-tests.ResultsCB stems exhibited a significantly higher mean peak torque at failure (205.3 Nm (SD 26.9)) than TS stems (159.5 Nm (SD 17.4); p = 0.012), calcar-wired TS (148.2 Nm (SD 38.6); p = 0.031), and diaphyseal-wired TS (164.9 Nm (SD 21.5); p = 0.027). This study did not demonstrate that wired-TS stems had a higher peak torque at failure than non-wired TS stems. Additionally, calcar wiring was not found to be stronger than diaphyseal wiring (p = 0.400). Four CB fractures occurred distal to the stem, whereas all TS fractures occurred at the mid-stem, simulating a Vancouver type B fracture. Interestingly, adding the diaphyseal wire shifted the fracture location more distally in four of the seven stems (p = 0.070).ConclusionIn this model, CB stems had greater resistance to torque than TS stems, which may explain the lower risk of PPF. Adding calcar or diaphyseal wires to the TS stems resulted in no significant change in peak torque to fracture. CB cemented stems should be considered in patients at high risk of PPF.Cite this article: Bone Joint J 2025;107-B(5 Supple A):32–37.

ABSTRACT Introduction Acute Compartment Syndrome (ACS) is a severe trauma caused by elevated intra-muscle-compartment pressure (ICP). The current standard method for diagnosis is to insert a needle into the muscle sterilely under anesthesia. However, to secure the environment is sometimes not easy and leads to delays in diagnosis. Recently, we have focused on shear wave ultrasound elastography (SWE) as an alternative, which can be done concisely in unclean environment and without anesthesia. We would like to report the usefulness of SWE for ACS diagnosis using 2-pedal walking turkey model recently developed in our lab. Materials and Methods A total of 32 1-year-old Bourbon turkeys were used. 5% solution of chicken albumin was infused continuously into the tibialis cranialis (TC) muscle using IV pump. The ICP was increased stepwise from 0 to 50 mmHg. During the rising of ICP, the correlation between values of SWE (kPa) and ICP (mmHg) was measured. After the ICP reached 50 mmHg, half of the turkeys were maintained at this pressure for 2 hours and the rest for 6 hours. After infusion, a fasciotomy was performed on the half turkey. Half of the turkeys were euthanized after 2 weeks and the rest after 6 weeks. SWE of TC muscle and walking gait data on turkeys using a portable walkway system were measured weekly until euthanasia. At euthanasia, isometric tetanic muscle force (ITF) tests to TC muscle and histological evaluations were performed. Results SWE value (kPa) was highly significantly correlated to the actual ICP (mmHg) (R2 = 0.91). Stance of ACS side leg were significantly extended, and swing of the control side shortened from the second to the third week after ACS in the 6 hours infusion-no-fasciotomy group (P < 0.05*). ITF was significantly reduced mainly in the 6 hours infusion group (P < 0.05*). Histological evaluation revealed that in the 6 hours infusion and 6 weeks survival group, both the muscle fiber and intercellular distances were significantly expanded (P < 0.05). Conclusion SWE seems to be a substitute measure of ICP in diagnosing ACS. With regard to our in vivo ACS model using turkey, survival at 50 mmHg ICP for 6 hours and 6 weeks post ACS would be an appropriate situation.

AbstractChordae tendineae, referred to as heart tendinous cords, act as tendons connecting the papillary muscles to the valves in the heart. Their role is analogous to tendons in the musculoskeletal system. Despite being exposed to millions of cyclic tensile stretches over a human's lifetime, chordae tendineae rarely suffer from overuse injuries. On the other hand, musculoskeletal tendinopathy is very common and remains challenging in clinical treatment. The objective of this study was to investigate the mechanism behind the remarkable durability and resistance to overuse injuries of chordae tendineae, as well as to explore their effects on flexor tenocyte biology. The messenger RNA expression profiles of chordae tendineae were analyzed using RNA sequencing and verified by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Interestingly, we found that periostin (Postn) and fibroblast growth factor 7 (FGF7) were expressed at significantly higher levels in chordae tendineae, compared to flexor tendons. We further treated flexor tenocytes in vitro with periostin and FGF7 to examine their effects on the proliferation, migration, apoptosis, and tendon‐related gene expression of flexor tenocytes. The results displayed enhanced cell proliferation ability at an early stage and an antiapoptotic effect on tenocytes, while treated with periostin and/or FGF7 proteins. Furthermore, there was a trend of promoted tenocyte migration capability. These findings indicated that Postn and FGF7 may represent novel cytokines to target flexor tendon healing. Clinical significance: The preliminary discovery leads to a novel idea for treating tendinopathy in the musculoskeletal system using specific molecules identified from chordae tendineae.

Abstract ObjectiveChondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism.MethodHuman primary chondrocytes isolated from articular cartilage of OA patients were treated with SNP alone or in combination with different doses of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3)II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localisation and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile, activation of ERK 1/2 pathway was determined by western blot. The autophagy inhibitors, 3-Methyladenine (3-MA), chloroquine (CQ) and a specific inhibitor of ERK1/2, SCH772984, were used respectively to confirm the autophagic effect of ASP.ResultsThe results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocytes proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of ERK1/2 pathway.ConclusionASP markedly rescued SNP-induced apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP a potential therapeutic supplementation for OA treatment.

Abstract ObjectiveChondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional Chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism.MethodHuman primary chondrocytes isolated from articular cartilage of OA patients were treated with SNP alone or in combination with different doses of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3)-II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localisation and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile，activation of ERK 1/2 pathway was determined by western blot. The autophagy inhibitors 3-Methyladenine (3-MA), chloroquine (CQ) and a specific inhibitor of ERK1/2, SCH772984, were used respectively to confirm the autophagic effect of ASP.ResultsThe results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocytes proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of ERK1/2 pathway.ConclusionASP markedly rescued SNP-induced chondrocyte apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP a potential therapeutic supplementation for OA treatment.

Abstract Objective Chondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional Chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism. Method Human primary chondrocytes isolated from articular cartilage of OA patients were treated with SNP alone or in combination with different dose of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3)-II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localisation and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile,activation of ERK 1/2 pathway was determined by western blot. The autophagy inhibitors 3-Methyladenine (3-MA), chloroquine (CQ) and a specific inhibitor of ERK1/2, SCH772984, were used respectively to confirm the autophagic effect of ASP. Results The results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocytes proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of ERK1/2 pathway.Conclusion ASP markedly rescued SNP-induced chondrocyte apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP a potential therapeutic supplementation for OA treatment.