Sonic hedgehog promotes chondrogenesis of rabbit bone marrow stem cells in a rotary cell culture system.

BACKGROUND: Sonic hedgehog (Shh) is an important signalling protein involved in the induction of early cartilaginous differentiation. Herein, we demonstrate that Shh markedly induces chondrogenesis of rabbit bone marrow stromal cells (BMSCs) under microgravity conditions, and promotes cartilage regeneration. RESULTS: In the rotary cell culture system (RCCS), chondrogenic differentiation was revealed by stronger Toluidine Blue and collagen II immunohistochemical staining in the Shh transfection group, and chondroinductive activity of Shh was equivalent to that of TGF-ß. Western blotting and qRT-PCR analysis results verified the stronger expression of Sox9, aggrecan (ACAN), and collagen II in rabbit BMSCs treated with Shh or TGF-ß in a microgravity environment. Low levels of chondrogenic hypertrophy, osteogenesis, and adipogenesis-related factors were detected in all groups. After transplantation in vivo, histological analysis revealed a significant improvement in cartilage and subchondral repair in the Shh transfection group. CONCLUSIONS: These results suggested that Shh signalling promoted chondrogenesis in rabbit BMSCs under microgravity conditions equivalent to TGF-ß, and improved the early stages of the repair of cartilage and subchondral defects. Furthermore, RCCS provided a dynamic culture microenvironment conducive for cell proliferation, aggregation and differentiation.

Chondrogenic differentiation of bone marrow-derived mesenchymal stem cells following transfection with Indian hedgehog and sonic hedgehog using a rotary cell culture system.

BACKGROUND: Indian hedgehog (IHH) and Sonic hedgehog (SHH) are important regulators of chondrogenesis. However, activation of IHH and SHH also promotes chondrocyte hypertrophy and ossification during chondrogenesis. The aims of this study were to investigate the effect of microgravity on IHH- and SHH-induced chondrogenic differentiation and to elucidate the role of microgravity in this process. METHODS: Adenovirus plasmids encoding the rabbit IHH gene and SHH genes were constructed in vitro and transfected into rabbit bone marrow-derived mesenchymal stem cells (BMSCs). A rotary cell culture system (RCCS), in which a dynamic three-dimensional culture system combines the mechanical environment with a three-dimensional culture surface, was used for cell culture and differentiation. During the induction of differentiation, expression levels of cartilage-related and cartilage hypertrophy-related genes and proteins were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting, respectively. Toluidine blue and collagen II immunohistochemical staining and annexin V-Cy3 staining were used to indicate investigate cartilage matrix synthesis and hypertrophic hypertrophy, respectively, on day 21 after induction of differentiation. RESULTS: In this study, IHH and SHH were shown to be equipotent inducers of chondrogenesis in rabbit BMSCs, as evidenced by strong staining for proteoglycans and collagen II, and increased expression of mRNAs and proteins associated with chondrogenesis in an RCCS environment. More importantly, chondrogenic hypertrophy and aging were effectively inhibited in the RCCS environment. In addition, levels of cartilage-related markers in the IHH and SHH transfection groups were initially increased and later decreased in the traditional two-dimensional environment, while cartilage hypertrophy-related factors revealed higher mRNA expression levels during induction. CONCLUSIONS: In summary, microgravity significantly promoted chondrogenic differentiation of BMSCs induced by IHH and SHH and attenuated chondrogenic hypertrophy and aging during chondrogenesis. Furthermore, exogenous IHH and SHH had the same effect on chondrogenic differentiation of BMSCs in the RCCS environment. This study provides further evidence of chondrogenic induction of BMSCs in vitro via IHH and SHH gene delivery.

Role of Organic Components in Electrocatalysis for Renewable Energy Storage.

Carbon dioxide electroreduction and water splitting are known as two promising strategies to convert renewable intermittent electrical energy into chemical energy. Thus, the three half-reactions, namely, CO2 reduction reaction, hydrogen evolution reaction, and the oxygen evolution counter reaction, in these two electrolytic processes have attracted wide research interest. Organic polymer electrocatalysts or electrocatalysts containing organic components play important roles in these catalytic processes. It has been shown that the organic molecules can efficiently catalyze the reactions themselves, and modulate the active sites towards high selectivity and efficiency. The roles of the organic molecules in conducting polymers, the metal complexes, and the framework materials are extracted for the three half-reactions mentioned above, and this comprehensive review will serve as a guide for future research and aid in the design of electrocatalysts related to organic molecules.

The p-Orbital Delocalization of Main-Group Metals to Boost CO2 Electroreduction.

Enhancing the p-orbital delocalization of a Bi catalyst (termed as POD-Bi) via layer coupling of the short inter-layer Bi-Bi bond facilitates the adsorption of intermediate *OCHO of CO2 and thus boosts the CO2 reduction reaction (CO2 RR) rate to formate. X-ray absorption fine spectroscopy shows that the POD-Bi catalyst has a shortened inter-layer bond after the catalysts are electrochemically reduced in situ from original BiOCl nanosheets. The catalyst on a glassy carbon electrode exhibits a record current density of 57 mA cm-2 (twice the state-of-the-art catalyst) at -1.16 V vs. RHE with an excellent formate Faradic efficiency (FE) of 95 %. The catalyst has a record half-cell formate power conversion efficiency of 79 % at a current density of 100 mA cm-2 with 93 % formate FE when applied in a flow-cell system. The highest rate of the CO2 RR production reported (391 mg h-1 cm2 ) was achieved at a current density of 500 mA cm-2 with formate FE of 91 % at high CO2 pressure.

Patterned liquid metal embedded in brush-shaped polymers for dynamic thermal management.

Interface thermal resistance has become a crucial barrier to effective thermal management in high-performance electronics and sensors. The growing complexity of operational conditions, such as irregular and dynamic surfaces, demands thermal interface materials (TIMs) to possess high thermal conductivity and soft elasticity. However, developing materials that simultaneously combine soft elasticity and high thermal conductivity remains a challenging task. Herein, we utilize a vertically oriented graphene aerogel (VGA) and rationally design liquid metal (LM) networks to achieve directional and adjustable pathways within the composite. Subsequently, we leverage the advantages of the low elastic modulus and high deformation capabilities of brush-shaped polydimethylsiloxane (BPDMS), together with the bicontinuous thermal conduction path constructed by VGA and LM networks. Ultimately, the designed composite of patterned liquid metal/vertically oriented graphene aerogel/brush-shaped PDMS (LM-VGA/BPDMS) shows a high thermal conductivity (7.11 W m-1 K-1), an ultra-low elastic modulus (10.13 kPa), excellent resilience, and a low interface thermal resistance (14.1 K mm2 W-1). This LM-VGA/BPDMS soft composite showcases a stable heat dissipation capability at dynamically changing interfaces, as well as excellent adaptability to different irregular surfaces. This strategy holds important application prospects in the fields of interface thermal management and thermal sensing in extremely complex environments.

The role of vitamin D on rotator cuff tear with osteoporosis.

Backgrounds: Osteoporosis (OP) is an important risk factor for rotator cuff tears (RCTs). However, the relationship and mechanism between rotator cuff injury and osteoporosis are unclear. Therefore, to investigate association between rotator cuff injury and osteoporosis, and find clinical characteristics, bone mineral density, bone metabolism markers, and nutrient levels in rotator cuff injury patients with or without osteoporosis. Methods: One hundred and four cases of patients (RCTs, n=32; RCTs-OP, n=72) who underwent rotator cuff injury and need arthroscopic rotator cuff repair between June 2021 and February 2022, along with the diagnosis of osteoporosis were identified from the dual-energy X-ray bone density screening(DXA). The outcome measure includes clinical characteristics, bone mineral density, bone metabolism markers, vitamins, and amino acids. Multivariable logistic regression analysis was applied to build a predicting model incorporating the feature selected in the least absolute shrinkage and selection operator regression model. Discrimination, calibration, and clinical usefulness of the predicting model were assessed using the C-index, calibration plot, and decision curve analysis. Internal validation was assessed using bootstrapping validation. Results: OP with RCTs has a lower level of in 25-vitD, osteocalcin (OCN), serum Ca2+, ornithine, diaminocaproic_acid but the high level of Vitamin_B12, PTH, Vitamin_D3,γ_aminobutyric_acid, Vitamin_C and Vitamin_E than RCTs patients without OP. Predictors contained in the prediction nomogram included lumber T score, femur T score, Niacin_B3, and vitamin D, reflecting the combined effect of vitamins on RCTs-related OP progression. The model has good discriminative ability with a C-index of 0.938(95% CI:-1.83-1.39) and good scaling ability. The high C-index value of 0.95 is still achievable with range validation. Analysis of decision curves showed that non-adherence is clinically useful when intervention decisions are at the 14% probability limit of non-adherence. Conclusion: This study supports the hypothesis that lumber T score, femur T score, Niacin_B3, and Vitamin D are valuable prognostic biomarkers on RCTs related OP progression. What is known about the subject: It is found that vitamin D are valuable prognostic biomarkers, reflecting the combined effect of vitamins on RCTs related OP progression. What this study adds to existing knowledge: These findings also highlight that nutrients condition such as vitamins and amino acids of patients provide a new understanding of the development of RCTs.

Synergistic effects of Indian hedgehog and sonic hedgehog on chondrogenesis during cartilage repair.

Sonic hedgehog (Shh) and Indian hedgehog (Ihh) have been shown to control the induction of early cartilaginous differentiation. However, it is unclear whether Ihh and Shh exert synergistic effects on chondrogenesis during articular cartilage repair. Herein, we investigate the effects of chondrogenesis of bone-derived mesenchymal stem cells (BMSCs) following co-transfection with Shh and Ihh via adenoviral vectors in vitro and in vivo. A rotary cell culture system (RCCS) and Cytodex 3 microcarriers were used to create a stereoscopic dynamic environment for cell culture. In the RCCS environment, BMSCs co-transfected with Ihh and Shh displayed stronger chondrogenic differentiation and chondrogenesis than BMSCs transfected with Ihh or Shh alone, and exhibited higher expression levels of Sox 9, ACAN and collagen II, stronger toluidine blue and collagen II immunohistochemical staining. After transplanted into the osteochondral defect at 8 weeks, Ihh/Shh co-transfected BMSCs showed a significantly better cartilage repair than BMSCs transfected with Ihh or Shh alone. Ihh and Shh have synergistic effects on the induction of chondrogenic differentiation and chondrogenesis under a microgravity environment, and help to repair damaged cartilage and reverse subchondral defects during the early stages.

The umbilical cord mesenchymal stem cell-derived exosomal lncRNA H19 improves osteochondral activity through miR-29b-3p/FoxO3 axis.

BACKGROUND: Our previous study revealed that the exosomal lncRNA H19 derived from umbilical cord mesenchymal stem cells (UMSCs) plays a pivotal role in osteochondral regeneration. In this study, we investigated whether the exosomal lncRNA H19 could act as a competing endogenous RNA (ceRNA) to potentiate osteochondral activity in chondrocytes. METHODS: Dual-luciferase reporter assay, RNA pull-down, RNA immunoprecipitation (RIP), and fluorescence in situ hybridization (FISH) were carried to verify the interaction between miR-29b-3p and both lncRNA H19 and the target mRNA FoxO3. Chondrocytes were treated with UMSC-derived exosomes, which highly expressing lncRNA H19 expression, followed by apoptosis, migration, senescence, and matrix secretion assessments. An in vivo SD rat cartilage defect model was carried out to explore the role and mechanism of lncRNA H19/miR-29b-3p. RESULTS: UMSCs were successfully identified, and exosomes were successfully extracted. Exosomes exhibited the ability to transfer lncRNA H19 to chondrocytes. Mechanistically, exosomal lncRNA H19 potentiated osteochondral activity by acting as a competing endogenous sponge of miR-29b-3p, and miR-29b-3p directly targeted FoxO3. Intra-articular injection of exosomes overexpressing lncRNA H19 could promote sustained cartilage repair; however, this effect could be undermined by miR-29b-3p agomir. CONCLUSIONS: Our study revealed a significant role in the development of strategies against cartilage defects for UMSC-derived exosomes that overexpress lncRNA H19. Exosomal H19 was found to promote chondrocyte migration, matrix secretion, apoptosis suppression, as well as senescence suppression, both in vitro and in vivo. The specific mechanism lies in the fact that exosomal H19 acts as a ceRNA against miR-29b-3p to upregulate FoxO3 in chondrocytes.

Exosomes derived from umbilical cord mesenchymal stem cells in mechanical environment show improved osteochondral activity via upregulation of LncRNA H19.

BACKGROUND: Exosomes derived from stem cells have been demonstrated to be good candidates for the treatment of osteochondral injury. Our previous studies have demonstrated that mechanical stimulation could be crucial for the secretion of exosomes derived from umbilical cord mesenchymal stem cells (U-MSCs). Therefore, we explore whether mechanical stimulation caused by a rotary cell culture system (RCCS) has a beneficial effect on exosome yield and biological function. METHODS: U-MSCs were subjected to an RCCS at different rotational speeds and exosomes were characterised by transmission electron microscopy, nanoparticle tracking analysis and western blotting. small-interfering RNAs of Rab27a (siRNA-Rab27a) was used to reduce exosome production. Quantitative real-time PCR (qRT-PCR) was used to detect the expression of mechanically sensitive long non-coding RNA H19 (LncRNA H19). The effects of exosomes on chondrocyte proliferation were examined using cell counting kit-8 (CCK-8), toluidine blue staining and a series of related genes. Annexin V-FITC and PI (V-FITC/PI) flow cytometry was used to detect the effect of exosomes on the inhibition of chondrocyte apoptosis. Macroscopic evaluation, MRI quantification and immunohistochemical staining were conducted to investigate the in vivo effects of exosomal LncRNA H19 through SD rat cartilage defect models. RESULTS: RCCS significantly promoted exosome production at 36 rpm/min within 196 h. Mechanical stimulation was able to increase the expression level of exosomes. The exosomal LncRNA H19 was found to promote chondrocyte proliferation and matrix synthesis and inhibit apoptosis in vitro. Chondral regeneration activity was lost in LncRNA H19-defective exosomes. The injection of exosomal LncRNA H19 in vivo resulted in improved macroscopic assessment, MRI quantification and histological analysis. Moreover, exosomal LncRNA H19 was able to relieve pain levels during the early stages of cartilage repair in an animal experiment. CONCLUSION: Our findings confirmed that mechanical stimulation can enhance exosome yield as well as biological function for the repair of cartilage defects. The underlying mechanism may be related to the high expression of LncRNA H19 in exosomes. The translational potential of this article: This study provides a theoretical support of optimizing exosome production. It advances the yield of mesenchymal stem cell exosome and facilitate the clinical application to repair of osteochondral damage.

Retracted Article: PVT1 depletion protects cartilage ATDC5 cells against LPS-induced inflammatory injury by regulating the miR-24/ADAMTS5 axis.

Background: Osteoarthritis is a common chronic arthritis among adults and cartilage dysfunction is largely responsible for osteoarthritis development. Long noncoding RNAs (lncRNAs) have been reported to be related to osteoarthritis progression. However, the mechanism that underlies the effect of lncRNA plasmacytoma variant translocation 1 (PVT1) on inflammatory injury in cartilage ATDC5 cells remains elusive. Methods: The quantity of PVT1 and microRNA-24 (miR-24) was detected in human cartilage ATDC5 cells after transfection of si-PVT1, si-con, PVT1 or pcDNA and lipopolysaccharide (LPS) treatment for 12 h. Inflammatory injury was investigated using cell viability, apoptosis and secretion of inflammatory cytokines. The interaction of miR-24 with PVT1 or a disintegrin-like metalloproteinase with thrombospondin motifs 5 (ADAMTS5) was probed by bioinformatics, luciferase activity, RNA pull down and Ago1 RNA immunoprecipitation (RIP) assays. The effect of PVT1 and miR-24 on ADAMTS5 expression was evaluated in ATDC5 cells by western blotting (WB). Results: Treatment of LPS induced elevated PVT1 and reduced miR-24 expression in ATDC5 cells. Moreover, LPS inhibited cell viability, increased apoptosis and inflammatory cytokine production. However, PVT1 depletion attenuated LPS-induced inflammatory injury in ATDC5 cells. In addition, miR-24 directly bound to PVT1 and its deficiency reversed the effect of PVT1 deletion in LPS-treated ATDC5 cells. Furthermore, ADAMTS5 was a target of miR-24 and aberrant expression of ADAMTS5 was regulated by PVT1 and miR-24. Conclusion: PVT1 abrogation protected against LPS-induced inflammatory injury in ATDC5 cells by coordinating with the miR-24/ADAMTS5 axis, opening up a novel avenue for osteoarthritis therapeutics.

Fabrication, pore structure and compressive behavior of anisotropic porous titanium for human trabecular bone implant applications.

Porous titanium with average pore size of 100-650 µm and porosity of 30-70% was fabricated by diffusion bonding of titanium meshes. Pore structure was characterized by Micro-CT scan and SEM. Compressive behavior of porous titanium in the out-of-plane direction was studied. The effect of porosity and pore size on the compressive properties was also discussed based on the deformation mode. The results reveal that the fabrication process can control the porosity precisely. The average pore size of porous titanium can be tailored by adjusting the pore size of titanium meshes. The fabricated porous titanium possesses an anisotropic structure with square pores in the in-plane direction and elongated pores in the out-of-plane direction. The compressive Young's modulus and yield stress are in the range of 1-7.5 GPa and 10-110 MPa, respectively. The dominant compressive deformation mode is buckling of mesh wires, but some uncoordinated buckling is present in porous titanium with lower porosity. Relationship between compressive properties and porosity conforms well to the Gibson-Ashby model. The effect of pore size on compressive properties is fundamentally ascribed to the aspect ratio of titanium meshes. Porous titanium with 60-70% porosity has potential for trabecular bone implant applications.

Slightly focused high-energy shockwave therapy: a potential adjuvant treatment for osteoporotic fracture.

Slightly focused high-energy shockwave (HESW) therapy is characterized by a wide focal area, a large therapy zone, easy positioning and less pain during treatment. The objective of this study was to perform for the first time an in vivo test of the slightly focused HESWs for osteoporotic fractures. Bilateral proximal tibial osteotomies were made in 30 ovariectomized (OVX) Sprague-Dawley rats and secured with internal fixation. The osteotomy site in the left tibia was subsequently treated with slightly focused HESWs with the energy flux density of 0.26 mj/mm(2), shock repetition frequency of 1 Hz and 2000 shocks (OVX + HESW group). The contralateral right tibia was not treated and served as the control (OVX group). Roentgenographic examination 2, 4, 6, and 8 weeks after osteotomy showed that HESW treatment accelerated tibia fracture healing in osteoporotic rats. Histological examination 2, 4, and 8 weeks after HESW treatment showed a greater inflammatory reaction in the OVX + HESW group, with more mature collagen and trabeculae than in the OVX group. Micro computer tomography (Micro-CT) scanning after 4 and 8 weeks showed that bone volume (BV), bone volume/tissue volume (BV/TV), mean trabecular thickness (Tb.Th), and mean trabecular number (Tb.N) were about 45.0% and 33.1%, 18.4% and 20.1%, 38.2% and 20.9%, 26.7% and 28.4%, respectively, higher in the treatment group than in the control group (P < 0.05); and the mean trabecular separation (Tb.Sp) was about 16.7% and 27.3% lower in the treatment group (P < 0.05). Four and eight weeks after HESW treatment, the maximum compressive callus endurance was about 72.3% and 25.5%, respectively, higher in the treatment group than in the control group (P < 0.05). These results show that slightly focused HESW therapy has a beneficial effect on osteoporotic tibial fracture healing. Slightly focused HESWs could increase callus endurance, induce bone formation, and improve trabecular bone microarchitecture and biomechanical properties.

Were you identified to be at high fracture risk by FRAX® before your osteoporotic fracture occurred?

With the increasing longevity and the growing size of the aging population, China is among the developing countries with the greatest burden of osteoporotic fractures (OFs). Identification of individuals at high fracture risk to provide early treatment in developing countries with limited resources remains a challenge. Our aim was to calculate the FRAX® values in a selected mainland Chinese population the day before the occurrence of an OF and to compare the results with the Osteoporosis Foundation (NOF) thresholds. To define a population at high fracture risk, we selected patients in the orthopedic emergency cohort from Shanghai Sixth People's Hospital, China. To calculate the FRAX® the day before the actual OF, the actual fracture was not considered as a previous fracture. Subjects with a FRAX® value lower than the NOF thresholds were not considered at high risk. One-hundred ninety-eight patients were included with a mean age of 69.9 ± 10.1 years old, and 78.8 % were female. Major fracture sites included hip (41.9 %), proximal humerus (22.2 %), forearm (27.8 %), spine (6.6 %), and pelvis (1.5 %). Overall, only two (1.0 %) patients had a 10-year major fracture probability ≥20 %, and 84 (42.4 %) patients had a 10-year hip fracture probability ≥3 %. More than half of the population was not identified to be at high risk by the FRAX® BMI (body mass index). For age groups 55-59, 60-69, 70-79, and 80-90 years old, respectively, the mean FRAX® BMI values (major OF/hip fracture) were 3.5/0.7, 5.7/1.8, 8.2/4.7, and 8.6/4.8 %. Dual-energy X-ray absorptiometry was available for 58 patients, and 41.2 % had a T-score ≤ -2.5 standard deviation (lumbar spine and/or femoral neck and/or total hip). Only six (17.6 %) patients with a normal or osteopenic BMD were classified at high risk by the FRAX® BMD (bone mineral density). The NOF thresholds could only identify fewer than half of the studied population to be at high risk the day before an actual OF, and the 10-year hip fracture probability seemed to perform better than the 10-year major fracture probability. Prospective population-based studies are needed to validate the prediction of Chinese FRAX® model and to establish ideal thresholds.