Advanced glycation end productions and tendon stem/progenitor cells in pathogenesis of diabetic tendinopathy

Enhancing osteogenic differentiation of diabetic tendon stem/progenitor cells through hyperoxia: Unveiling ROS/HIF-1α signalling axis

Diabetic calcific tendinopathy is the leading cause of chronic pain, mobility restriction, and tendon rupture in patients with diabetes. Tendon stem/progenitor cells (TSPCs) have been implicated in the development of diabetic calcified tendinopathy, but the molecular mechanisms remain unclear. This study found that diabetic tendons have a hyperoxic environment, characterized by increased oxygen delivery channels and carriers. In hyperoxic environment, TSPCs showed enhanced osteogenic differentiation and increased levels of reactive oxygen species (ROS). Additionally, hypoxia-inducible factor-1a (HIF-1a), a protein involved in regulating cellular responses to hyperoxia, was decreased in TSPCs by the ubiquitin-proteasome system. By intervening with antioxidant N-acetyl-L-cysteine (NAC) and overexpressing HIF-1a, we discovered that blocking the ROS/HIF-1a signalling axis significantly inhibited the osteogenic differentiation ability of TSPCs. Animal experiments further confirmed that hyperoxic environment could cause calcification in the Achilles tendon tissue of rats, while NAC intervention prevented calcification. These findings demonstrate that hyperoxia in diabetic tendons promotes osteogenic differentiation of TSPCs through the ROS/HIF-1a signalling axis. This study provides a new theoretical basis and research target for preventing and treating diabetic calcified tendinopathy.

Midfoot Amputations as Adjuncts to Limb Preservation

Midfoot amputations are viable options for limb preservation in cases of forefoot infection, diabetic ulcers, critical limb ischemia, trauma, or malignancy to avoid major lower-extremity amputation. Each level of midfoot amputation has limitations to consider including wound healing problems, soft-tissue contracture, or need for revisional amputations. However, some of these facets can be addressed perioperatively. Each midfoot amputation has benefits as viable options for limb and functional preservation and to avoid major limb amputation. There currently is no set guideline for level of midfoot amputation in patients with critical limb ischemia. Levels of amputation are determined by multiple factors including but not limited to degree of tissue loss, vascular status, the ability to preserve function, surgeon experience, and pertinent patient factors. This approach to limb salvage is best performed from a multi-disciplinary perspective.

Platelet Rich Plasma Therapy in Achilles and Patellar Tendinopathies: Outcomes in Subjects with Diabetes (A Retrospective Case-Control Study)

Introduction: Diabetes mellitus (DM) is associated with a high risk of chronic degenerative Achilles (AT) and Patellar (PT) tendinopathies and ruptures. Growth factors (GFs) synthesis in diabetics is substantially decreased in human connective tissues, including in tendons. Platelet Rich Plasma (PRP), which is enriched in GFs, might prove of great help in tendon healing. The aim of the study was to assess whether pre-existent DM or Impaired Glucose Tolerance (IGT) could influence the clinical outcome in subjects undergoing PRP treatment. Methods: Sixty subjects with diabetes/pre-diabetes and sixty euglycemic controls, matched for sex and age, were enrolled. Patients suffering from proximal insertional PT and mid-portion AT, treated with PRP therapy, were included in the study. To assess the basal status and the efficacy of the therapy after 3 and 6 months, the Victorian Institute of Sport Assessment (VISA) questionnaire and the Ultrasound methodology study were used. Patient satisfaction was assessed by means of the Likert Scale. Results: In the population study at 6 months, the mean VISA-score increased (8.92 ± 0.67; p-value < 0.001). The improvement in the diabetic group was less evident compared to the controls (-2.76 ± 0.95; p-value = 0.003). Even though the improvement was poor, it was still significant. MCID analysis revealed that diabetics had higher risk of therapeutic unsuccess. Logistic regression analysis was applied to assess factors associated with unsatisfactory results (Likert-scale) of PRP treatment: AT (O.R.: 3.05; 95%CI: 1.40-6.64; p-value = 0.005), higher BMI values (O.R.: 1.02; 95%CI: 1.01-1.04; p-value = 0.01), and lower VISA score values at baseline (O.R.: 0.95; 95%CI: 0.90-0.99; p-value = 0.04). Conclusions: PRP treatment in AT and PT chronic tendinopathies resulted in less favorable results in subjects with diabetes compared with euglycemic subjects. Moreover, the subjects with PT showed better results than those with AT.

Misconceptions about trigger finger: a scoping review. Definition, pathophysiology, site of lesion, etiology. Trigger finger solving a maze

Trigger finger (TF) is a disorder characterized by snapping or locking a finger. It has a prevalence of greater than 3% in the general population; however, this estimate could be increased to 5% up to 20% in diabetic patients. Some unreal ambiguity about definition, pathophysiology, site of lesion, and etiology are found among researchers and clinicians, leading to a lack of understanding of all aspects of the disease and improper management as many clinicians proceed to anti-inflammatory medications or steroids injection without in-depth patient evaluation. Original articles cited up to 2022, found through a Google search using the specified keywords, have been used in this review. Close-access articles were accessed through our researcher account with the Egyptian Knowledge Bank. In this review, we will focus on pathophysiology to present all possible findings and etiology to represent all risk factors and associated diseases to assess and confirm a diagnosis and the exact location of pathology hence better treatment modalities and reducing the recurrence of the pathology.

HMGB1 Modulates High Glucose-Induced Erroneous Differentiation of Tendon Stem/Progenitor Cells through RAGE/β-Catenin Pathway

The association of tendinopathy with diabetes has been well recognized. Tendon stem/progenitor cells (TSPCs) play critical roles in tendon repair, regeneration, and homeostasis maintenance. Diabetic TSPCs exhibit enhanced erroneous differentiation and are involved in the pathogenesis of diabetic tendinopathy, whereas the underlying mechanism of the erroneous differentiation of TSPCs remains unclear. Here, we showed that high glucose treatment promoted the erroneous differentiation of TSPCs with increased osteogenic differentiation capacity and decreased tenogenic differentiation ability, and stimulated the expression and further secretion of HMGB1 in TSPCs and. Functionally, exogenous HMGB1 significantly enhanced the erroneous differentiation of TSPCs, while HMGB1 knockdown mitigated high glucose-promoted erroneous differentiation of TSPCs. Mechanistically, the RAGE/β-catenin signaling was activated in TSPCs under high glucose, and HMGB1 knockdown inhibited the activity of RAGE/β-catenin signaling. Inhibition of RAGE/β-catenin signaling could ameliorate high glucose-induced erroneous differentiation of TSPCs. These results indicated that HMGB1 regulated high glucose-induced erroneous differentiation of TSPCs through the RAGE/β-catenin signaling pathway. Collectively, our findings suggest a novel essential mechanism of the erroneous differentiation of TSPCs, which might contribute to the pathogenesis of diabetic tendinopathy and provide a promising therapeutic target and approach for diabetic tendinopathy.

Effect of Aging on Tendon Biology, Biomechanics and Implications for Treatment Approaches

Tendon aging is associated with an increasing prevalence of tendon injuries and/or chronic tendon diseases, such as tendinopathy, which affects approximately 25% of the adult population. Aged tendons are often characterized by a reduction in the number and functionality of tendon stem/progenitor cells (TSPCs), fragmented or disorganized collagen bundles, and an increased deposition of glycosaminoglycans (GAGs), leading to pain, inflammation, and impaired mobility. Although the exact pathology is unknown, overuse and microtrauma from aging are thought to be major causative factors. Due to the hypovascular and hypocellular nature of the tendon microenvironment, healing of aged tendons and related injuries is difficult using current pain/inflammation and surgical management techniques. Therefore, there is a need for novel therapies, specifically cellular therapy such as cell rejuvenation, due to the decreased regenerative capacity during aging. To augment the therapeutic strategies for treating tendon-aging-associated diseases and injuries, a comprehensive understanding of tendon aging pathology is needed. This review summarizes age-related tendon changes, including cell behaviors, extracellular matrix (ECM) composition, biomechanical properties and healing capacity. Additionally, the impact of conventional treatments (diet, exercise, and surgery) is discussed, and recent advanced strategies (cell rejuvenation) are highlighted to address aged tendon healing. This review underscores the molecular and cellular linkages between aged tendon biomechanical properties and the healing response, and provides an overview of current and novel strategies for treating aged tendons. Understanding the underlying rationale for future basic and translational studies of tendon aging is crucial to the development of advanced therapeutics for tendon regeneration.

Effect of Diabetes on Tendon Structure and Function: Not Limited to Collagen Crosslinking

Diabetes mellitus (DM) is associated with musculoskeletal complications-including tendon dysfunction and injury. Patients with DM show altered foot and ankle mechanics that have been attributed to tendon dysfunction as well as impaired recovery post-tendon injury. Despite the problem of DM-related tendon complications, treatment guidelines specific to this population of individuals are lacking. DM impairs tendon structure, function, and healing capacity in tendons throughout the body, but the Achilles tendon is of particular concern and most studied in the diabetic foot. At macroscopic levels, asymptomatic, diabetic Achilles tendons may show morphological abnormalities such as thickening, collagen disorganization, and/or calcific changes at the tendon enthesis. At smaller length scales, DM affects collagen sliding and discrete plasticity due to glycation of collagen. However, how these alterations translate to mechanical deficits observed at larger length scales is an area of continued investigation. In addition to dysfunction of the extracellular matrix, tendon cells such as tenocytes and tendon stem/progenitor cells show significant abnormalities in proliferation, apoptosis, and remodeling capacity in the presence of hyperglycemia and advanced glycation end-products, thus contributing to the disruption of tendon homeostasis and healing. Improving our understanding of the effects of DM on tendons-from molecular pathways to patients-will progress toward targeted therapies in this group at high risk of foot and ankle morbidity.

The Association Between Diabetes Mellitus and Osteoarthritis: Does Diabetes Mellitus Play a Role in the Severity of Pain in Osteoarthritis?

Osteoarthritis (OA) is one of the most prevalent degenerative joint diseases, which results in the inevitable destruction of joints leading to pain and joint immobility. Some studies have reported a potential link between diabetes mellitus (DM) and the worsening symptoms and severity of OA. Based on our literature review, the microcellular environment of patients with DM showed accelerated joint destruction and increased inflammation in every anatomical aspect of the joint including the bones, tendons, ligaments, cartilage, and synovium. Additionally, the biomechanical and biochemical properties of these tissues were more severely impacted in patients with DM and OA compared to those without DM, suggesting that DM plays an important role in the pathogenesis of OA. Specifically, we found that advanced glycation end products (AGEs) are the key to inducing the acceleration of joint destruction; however, their role in the pathogenesis has yet to be fully mapped out. In this narrative review, we aim to explore the role that DM plays in the acceleration of OA leading to increased reports of joint pain in those with both diseases. We believe this topic of discussion to be important due to the increased prevalence of both diseases over the last several decades, potentially leading to an increased medical burden on both patients and the community at large.

Evaluating the role of type 2 diabetes mellitus in rotator cuff tendinopathy: Development and analysis of a novel rat model

OBJECTIVE

To establish and validate an intact rotator cuff rat model for exploring the pathophysiological effects of type 2 diabetes on the rotator cuff tendon in vivo.

METHODS

A total of 45 adult male rats were randomly divided into a control group (n = 9) and type 2 diabetes group (n=36). The rats were sacrificed at 2 weeks (T2DM-2w group, n=9), 4 weeks (T2DM-4w group, n=9), 8 weeks (T2DM-8w group, n=9), and 12 weeks (T2DM-12w group, n=9) after successful modeling of type 2 diabetes. Bilateral shoulder samples were collected for gross observation and measurement, protein expression(enzyme-linked immunosorbent assay,ELISA), histological evaluation, biomechanical testing, and gene expression (real-time quantitative polymerase chain reaction, qRT-PCR).

RESULTS

Protein expression showed that the expression of IL-6 and Advanced glycation end products (AGEs)in serum increased in type 2 diabetic group compared with the non-diabetic group. Histologically, collagen fibers in rotator cuff tendons of type 2 diabetic rats were disorganized, ruptured, and with scar hyperplasia, neovascularization, and extracellular matrix disturbances, while Bonar score showed significant and continuously aggravated tendinopathy over 12 weeks. The biomechanical evaluation showed that the ultimate load of rotator cuff tendons in type 2 diabetic rats gradually decreased, and the ultimate load was negatively correlated with AGEs content. Gene expression analysis showed increased expression of genes associated with matrix remodeling (COL-1A1), tendon development (TNC), and fatty infiltration (FABP4) in tendon specimens from the type 2 diabetic group.

CONCLUSION

Persistent type 2 diabetes is associated with the rupture of collagen fiber structure, disturbance in the extracellular matrix, and biomechanical decline of the rotator cuff tendon. The establishment of this new rat model of rotator cuff tendinopathy provides a valuable research basis for studying the cellular and molecular mechanisms of diabetes-induced rotator cuff tendinopathy.