Connective Tissue Research最新文献

Purpose: After peripheral nerve injury (PNI), prolonged denervation of the target muscle prevents adequate reinnervation even if the nerve is repaired. The aim of this work is to analyze the effect of intramuscular Platelet-Rich Plasma (PRP) in a denervated muscle due to PNI.Materials and.

Methods: An irreversible PNI was generated in the common peroneal nerve of 80 Wistar rats by nerve resection. Animals were divided into groups: non-treatment (NT), saline (S) and PRP (PRP). 200 uL of saline (S group) and PRP (PRP group) were infiltrated intramuscularly into the tibialis anterior muscle on a weekly basis, from surgery to sacrifice (at 2, 4 and 7 weeks). Muscles were histologically processed for immunofluorescence and Western blotting. Effects on nicotinic acetylcholine receptor (nAChR), satellite cells (SC) and myogenin expression were analyzed. Comparisons were performed by two-way analysis of variance (ANOVA).

Results: PRP had a platelet concentration 1.5-fold higher than blood, without erythrocytes and leukocytes. The PRP group had a higher percentage weight than the S and NT groups (p < 0.05). The levels of nAChRα1 and nAChRε subunit were lower in the PRP group relative to the NT and S (p < 0.05), while the nAChRγ subunit showed an increase in the PRP group (p < 0.05). The activation of SCs was higher in the PRP group compared to NT and S groups (p < 0.05).

Conclusion: PRP treatment can modulate NMJ configuration as well as key myogenic regulatory factors in denervated muscle, enhancing SC activation while mitigating muscle atrophy.

Aim: We aimed to investigate whether α-ketoglutarate (AKG) can promote autophagic activity under a peri-implant condition to enhance the osseointegration of dental implant in rats with osteoporosis (OP).

Methods: Con, Model and AKG groups were established for the random allocation of thirty rats (n = 10). Their bone metabolism indicators were measured. The peri-implant bone morphology was detected by toluidine blue staining, the peri-implant bone tissue healing was detected, and the implant torque was measured.

Results: In comparison to the Con group, the bone metabolism indicators [bone volume/tissue volume ratio (BV/TV), trabecular number (Tb.N), and osseointegration index (OI)], bone-implant contact (BIC) rate, bone mass in the cancellous area, dislocation torque, protein and mRNA expressions of bone morphogenetic protein-2 (BMP-2), RUNX2 and Beclin1, and LC3II/LC3I ratio in bone tissues decreased significantly in the Model group, with a significant enlargement of trabecular space (Tb.Sp) (p < 0.05). In comparison with the Model group, the AKG group had significant increases in Tb.N, BV/TV, OI, BIC rate, bone mass in the cancellous area, dislocation torque, mRNA plus protein expressions of BMP-2, Runt-related transcription factor 2 and Beclin1, and LC3II/light chain 3I ratio in bone tissues, in addition to a significant reduction of Tb.Sp (p < 0.05).

Conclusions: AKG may relieve the bone metabolism disorders and enhance the osteogenic differentiation and osseointegration of implants in OP rats by promoting peri-implant autophagy.

Purpose: Knee joint distraction is a surgical procedure with cartilage-regenerating properties. The composition of joint distraction-regenerated cartilage in human patients is poorly documented. In this case-study, provided a unique opportunity to biomolecularly characterize the regenerated tissue from a patient who underwent bilateral distraction and later knee replacements.

Methods: Knee joint distraction was conducted using an external fixation frame and total knee arthroplasty was performed several years later. Radiographic imaging was performed to assess the status of the knee joint prior, during and after clinical interventions. Following total knee replacement, cartilage biopsies were collected and processed for tissue sectioning and histochemical staining. Tandem mass-spectrometry proteomics analysis was used to characterize and compare the proteomic composition.

Results: Both knee joints showed joint-space improvement pre- and post-knee joint distraction. Regenerated cartilage was white with an irregular surface, while native (lateral) cartilage had a yellow appearance and smooth surface. Histochemical staining showed higher Safranin-O positivity in native cartilage compared to regenerated cartilage, and differences in collagen structure. Proteomic analysis did not reveal major differences in cartilage extracellular matrix protein abundance. Bioinformatic analyses revealed enrichment in ribosomal proteins (regenerated cartilage) and RNA Polymerase II Transcription Termination (native cartilage).

Conclusion: Histologically, knee joint distraction-regenerated cartilage showed less glycosaminoglycans and disorganized collagen compared to native cartilage. However, mass-spectrometry has no major differences in extracellular matrix protein abundance, with proteomic clues suggesting protein translation regulation as a potential mechanism for regeneration.

Aims: Obesity increases tendinopathy's risk, but its mechanisms remain unclear. This study examined the effect of high-fat diet (HFD)-induced obesity on the outcomes and inflammation of collagenase-induced (CI) tendon injury.

Methods: Mice were fed with standard chow (SC) or HFD for 12 weeks. Bacterial collagenase I or saline was injected over the patellar tendons of each mouse. At weeks 2 and 8 post-injection, the patellar tendons were harvested for histology, immunohistochemical staining, and gait analysis. The difference (Δ) of limb-idleness index (LII) at the time of post-injury and pre-injury states was calculated. Biomechanical test of tendons was also performed at week 8 post-injection.

Results: HFD aggravated CI tendon injury with an increase in vascularity and cellularity compared to SC treatment. The histopathological score (week 2: p = 0.025; week 8: p = 0.013) and ΔLII (week 2: p = 0.012; week 8: p = 0.005) were significantly higher in the HFD group compared to those in the SC group after CI tendon injury. Stiffness (saline: p = 0.003; CI: p = 0.010), ultimate stress (saline: p < 0.001; CI: p = 0.006), and Young's modulus (saline: p = 0.017; CI: p = 0.007) were significantly lower in the HFD group compared to the SC group at week 8 after saline or collagenase injection. HFD induced higher expression of IL-1β (week 2: p = 0.010; week 8: p = 0.025) and MMP-1 (week 2: p = 0.010; week 8: p = 0.004) compared to SC treatment after CI tendon injury at both time points.

Conclusions: HFD-induced obesity exacerbated histopathological, functional, and biomechanical changes in the CI tendon injury model, which was associated with an upregulation of IL-1β and MMP-1.

Background: Collagen XI is a fibril-forming collagen typically associated with type II collagen tissues but is also expressed in type I collagen-rich tendons, especially during development. We previously showed that tendon-targeted (Scx-Cre) Col11a1 knockout mice have smaller tendons in adulthood with aberrant fibril structure and impaired mechanical properties. However, the manifestation of this phenotype is not clearly understood. Therefore, our objective is to define the spatiotemporal roles of collagen XI in tendon structure-function during postnatal development. Given the high expression of collagen XI during embryonic development, we hypothesized that collagen XI knockout leads to the deposition of weakened extracellular matrix during early postnatal timepoints, disrupting the establishment of tendon structure and function.

Methods: Patellar and Achilles tendons from postnatal (P) days 0, 10, 20, and 30 tendon-targeted scleraxis-Cre heterozygous and homozygous Col11a1 knockout mice were evaluated for morphology, nuclear organization, fibril morphology, mechanical properties, and gene expression.

Results: At P0, there were no differences in tendon length or fibril diameter of either tendon. By P10, striking structural and functional differences emerged, with collagen XI deficiency resulting in increased tendon length, a heterogeneous and larger diameter population of fibrils, and inferior mechanical properties in both patellar and Achilles tendons. Differences increased in magnitude through P30, supporting our hypothesis that impaired structure-function during postnatal development may drive tendon lengthening and reduced mechanical properties.

Conclusions: Though collagen XI is a quantitatively minor component of the tendon extracellular matrix, these results highlight the critical role of collagen XI in the acquisition of tendon structure-function.

Background: Checkpoint kinase 2 (CHEK2) and its regulated tumor protein p53 (TP53) have been correlated with osteogenic differentiation of osteoblast-like cells. Based on bioinformatics predictions, this study aims to investigate the effect of the CHEK2/TP53 axis on osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and to explore the regulatory mechanism.

Methods: PDLSCs were isolated from human impacted wisdom teeth, and they were cultured in normal medium (NM) or osteogenic medium (OM). Protein levels of CHEK2 and TP53 were examined using western blot analysis. Osteogenic differentiation ability of PDLSCs was analyzed by measuring marker proteins (RUNX2, OCN, and OSX), ALP activity, and ALP staining. Molecular interaction between NEDD4 like E3 ubiquitin protein ligase (NEDD4L) and CHEK2 was examined by ubiquitination and co-immunoprecipitation assays. Gain- and loss-of function assays of NEDD4L, CHEK2, and TP53 were performed to analyze their function in osteogenic differentiation of PDLSCs. A rat model of mandibular bone defect was generated for in vivo validation.

Results: NEDD4L was upregulated, while CHEK2 and TP53 were downregulated in PDLSCs cultured in OM. CHEK2 protected TP53 from degradation, while NEDD4L reduced CHEK2 protein level by ubiquitination modification. NEDD4L silencing reduced osteogenic differentiation ability of PDLSCs both in vitro and in vivo, which was restored by CHEK2 silencing. By contrast, CHEK2 overexpression blocked the osteogenic differentiation of PDLSCs in vitro.

Conclusion: This study demonstrates that NEDD4L affects protein stability of the CHEK2/TP53 axis through ubiquitination modification, thus increasing osteogenic differentiation of PDLSCs.

Purpose: The vocal folds (VFs) are among the most mechanically active connective tissues, vibrating between 80 and 250 hz during speech. Overall VF function is determined by the composition and structure of their extracellular matrix (ECM). During tissue maturation, the VFs remodel from a monolayer of collagen fibers to a tri-layered structure, affecting tissue biomechanics. However, age-related VF ECM remodeling remains poorly understood since few studies have explored the proteins governing collagen fibrillogenesis or the non-collagenous ECM components critical for VF elasticity.

Materials and methods: VFs from immature, sexually mature, and skeletally mature rats were evaluated by endoscopy, histology, and electron microscopy for cellular and biochemical composition, ECM organization, and proteoglycan distribution. Nanoindentation modulus was determined by atomic force microscopy.

Results: Collagen fiber abundance, maturity, and alignment are low in immature rats but show an age-dependent increase during tissue maturation. Lumican and fibromodulin, which regulate early-stage collagen fibril formation, are distributed throughout the VFs, and their abundance decreases with age. Decorin, involved in collagen organization, is concentrated just beneath the epithelium and increases with age. Elastin levels increase during tissue maturation, but hyaluronic acid abundance and distribution remain consistent with age. VF nanoindentation modulus trends toward a decrease with age.

Conclusion: This work identifies changes in VF ECM composition and organization during tissue maturation, focusing on proteins that regulate collagen fibrillogenesis, fiber assembly, and VF biomechanics. These findings may inform the development of pro-reparative therapies designed to influence collagen network structure and overall ECM dysregulation in a number of laryngeal pathologies.

Purpose/aim: Metabolic disorders are risk factors for rotator cuff injuries, which suggests that the rotator cuff is sensitive to local metabolic fluctuations. However, the link between the metabolic microenvironment and pathologic features of acute tear versus chronic degeneration is currently unknown. The overarching goal of this study was to evaluate alterations in tendon metabolite profiles following acute tear or chronic degeneration of the rotator cuff. We hypothesized that injury types (acute tear vs. chronic degeneration) would result in distinct metabolite profiles relative to clinically unaffected tendon controls.

Materials and methods: We utilized untargeted metabolomics to identify pathways that were altered at the time of rotator cuff repair (RCR; acute tear) or reverse total shoulder arthroplasty (rTSA; chronic degeneration) relative to total shoulder arthroplasty controls (TSA; tendon clinically unaffected).

Results: Acute tears to the rotator cuff were associated with an overall decrease in tendon metabolites. This global decrease was primarily associated with glycolic acid and decreased tricarboxylic acid (TCA) cycle activity. Conversely, chronic tendon specimens from patients undergoing rTSA showed an overall increase in metabolites. Most notably, chronic injury was associated with increased levels of multiple amino acids including alanine, aspartate, lysine, and proline.

Conclusions: Overall, this study demonstrates that distinct metabolite profiles are associated with injury types, and that therapeutic strategies should address both cellular and matrix components regardless of injury induction. The specific pathways identified paired with validated, established, treatment methods may serve as novel therapeutic targets for patients who suffer from rotator cuff injuries.

Platelet-rich plasma (PRP) has emerged as a promising therapeutic approach in regenerative medicine. It contains various growth factors and bioactive molecules that play pivotal roles in tissue repair, regeneration, and inflammation modulation. This comprehensive narrative review delves into the therapeutic potential of PRP in experimental goat and sheep research, exploring recent advancements, challenges, and future prospects in the field. PRP has been explored for its application in musculoskeletal injuries, wound healing, and orthopedic conditions. Studies have demonstrated the ability of PRP to accelerate tissue healing, reduce inflammation, and improve the overall quality of healing. Recent advancements in PRP technology have led to the development of novel formulations and delivery methods to enhance its therapeutic efficacy. PRP has shown promise in tendon and ligament injuries, osteoarthritis, and bone fractures in experimental goat and sheep research. Despite these advancements, several challenges and opportunities exist to harness the full therapeutic potential of PRP in regenerative medicine. Standardizing PRP preparation protocols, including blood collection techniques, centrifugation parameters, and activation methods, is essential to ensure consistency and reproducibility of the findings. Moreover, further research is needed to elucidate the optimal dosing, frequency, and timing of PRP administration for different clinical indications. Research conducted in goat and sheep models provides evidence supporting the translational potential of PRP in tissue engineering and regenerative medicine. By harnessing the regenerative properties of PRP and leveraging insights from preclinical studies, researchers can develop innovative therapeutic strategies to address unmet clinical needs and improve patient outcomes in diverse medical specialties.