miRNAs Related to Different Processes of Fracture Healing: An Integrative Overview

A Bioligical Perspective on the role of miR-206 in Colorectal cancer

MicroRNAs (miRs) have emerged as pivotal regulators in the development and progression of colorectal cancer (CRC), and MicroRNA-206 (miR-206) has garnered attention as a potentially influential factor. However, the specific biological functions and complete mechanistic understanding of miR-206 in CRC remain largely uncharacterized. This study aims to bridge this research gap by providing a comprehensive analysis of miR-206's role in CRC. An exploration of the molecular mechanisms regulated by miR-206, its intricate interplay with target genes, and its significant impact on cellular processes highlights its potential utility as both a diagnostic marker and a therapeutic target. The significance of this research lies in potentially enabling the development of innovative therapeutic approaches, ultimately aiming to improve prognosis and survival rates in CRC patients by elucidating the functions of miR-206. Critical pathways, such as c-Met and PTEN/AKT, play crucial roles within the regulatory network of miR-206 in CRC and impact various cellular processes involved in CRC pathogenesis, metastasis, and treatment response. Understanding the complex interactions between miR-206 and key signaling pathways like c-Met and PTEN/AKT is crucial for understanding the underlying mechanisms driving CRC initiation and progression. This knowledge can inform the development of targeted therapeutic interventions, potentially leading to improved patient outcomes and advances in CRC management.

Mineralized Osteoblast-Derived Exosomes and 3D-printed Ceramic-based Scaffolds for Enhanced Bone Healing: A Preclinical Exploration

In regenerative medicine, addressing the complex challenge of bone tissue regeneration demands innovative strategies. Exosomes, nanoscale vesicles rich in bioactive molecules, have shown great promise in tissue repair. This study focuses on exosomes derived from mineralized osteoblasts (MOBs), which play a pivotal role in bone formation. We investigated the therapeutic potential of exosomes isolated from osteoblasts cultured in osteogenic medium for 21 days, delivered via 3D-printed gyroid scaffolds composed of hydroxyapatite (HA) and tricalcium phosphate (TCP). The exosomes were characterized through nanoparticle tracking analysis to determine size, morphology, and concentration, while proteomics revealed their cargo contents. In vitro, rabbit bone marrow mesenchymal stromal cells (rBMSCs) were cultured as monolayers and within ceramic scaffolds, where MOB-derived exosomes were shown to promote osteogenic differentiation. In vivo, their osteoconductive and bone augmentation capabilities were evaluated in two rabbit calvarial models, while the osteoinductive potential was further tested in a heterotopic mouse model. Neo-bone formation was assessed using µCT and histological analysis. Our findings demonstrated that MOB-derived exosomes upregulated bone-related gene expression and promoted mineralization in rBMSCs, even in the absence of osteogenic medium. Proteomics confirmed the presence of bone-associated proteins in these exosomes. In rabbit models, however, exosomes did not significantly enhance bone formation. In contrast, in the heterotopic mouse model, exosomes functionalized onto ceramic scaffolds exhibited strong osteoinductive activity. This study highlights the potential of MOB-derived exosomes to enhance 3D-printed ceramic scaffolds for bone regeneration, offering a promising avenue for bone healing without the need for additional growth factors or stem cells. STATEMENT OF SIGNIFICANCE: The here presented report of our project not only advances our understanding of the role of exosome-functionalized scaffolds in bone regeneration but also proposes a promising alternative to traditional growth factor- or cell-based approaches. We are confident that this study represents a novel and impactful contribution to the field.

Serum miR-519d-3p and BMP2: potential early diagnostic markers and their mechanism in delayed fracture healing

BACKGROUND

Delayed fracture healing (DFH) affects patients' quality of life, and there are limitations in diagnosis by CT scan. The purpose of the study is to evaluate the potential and mechanism of clinical application of miRNAs in DFH for early diagnosis and intervention.

METHODS

Serum samples were obtained from delayed and normal fracture healing patients and the levels of miR-519d-3p and BMP2 were measured by RT-qPCR, and the value of both in the diagnosis of DFH was assessed by ROC curve. Cell viability and apoptosis were monitored using CCK8 kit and flow cytometry, respectively, and mRNA expression of osteogenesis and apoptosis-related genes were detected by RT-qPCR. The molecular interactions were verified using luciferase reporter gene system and RIP technique.

RESULTS

Up-regulation of miR-519d-3p expression and down-regulation of BMP2 in the serum of fracture patients four weeks after surgery can be used as an early warning marker of DFH and a risk factor for poor fracture healing. Further studies showed that overexpression of miR-519d-3p markedly inhibited the expression of RUNX2, OCN and ALP and prevented osteoblast differentiation. Meanwhile, it inhibited cell viability, promoted apoptosis, upregulated Bax and Cleaved-caspase-3 mRNA expression, and downregulated Bcl-2 expression. BMP2, targeted by miR-519d-3p, enhanced osteogenesis and reversed the inhibitory of action miR-519d-3p.

CONCLUSIONS

Serum miR-519d-3p and BMP2 can be used as early diagnostic markers for DFH. miR-519d-3p inhibited osteogenesis by targeting BMP2, which may slow down fracture healing.

Surgical suction filter-derived bone graft displays osteogenic miRNA and mRNA patterns

PURPOSE

Recently, a surgical suction filter device was introduced which aims at generating a suction filter-derived bone grafting substitute (SF-BGS). The osteogenic capacity of this grafting material, however, is unclear. MicroRNAs (miRNAs) and osteogenic mRNAs may influence these processes. The aim of this study was therefore to investigate the quality of the SF-BGS by determining the expression of miRNAs and osteogenic mRNAs.

METHODS

Samples were collected during non-union surgery. Upon exposure of the intramedullary canal, the surgical vacuum system was fitted with the suction filter device containing collagen complex and synthetic β-TCP: (Ca3(PO4)2, granule size 5-8 mm, total volume 10 mL (Cerasorb Foam®, Curasan AG, Kleinostheim, Germany). As a control, venous blood was used as in current clinical practice. Samples were snap-frozen and mechanically disrupted. MiRNAs and mRNAs were isolated, transcribed, and pooled for qPCR analysis. Lastly, mRNA targets were determined through in silico target analyses.

RESULTS

The study population consisted of seven patients with a posttraumatic long bone non-union (4♀; mean age 54 ± 16 years). From the array data, distinct differences in miRNA expression were found between the SF-BGS and control samples. Osteogenic marker genes were overall upregulated in the SF-BGS. Qiagen IPA software identified 1168 mRNA targets for 43 of the overall deregulated miRNAs.

CONCLUSION

This study revealed distinctly deregulated and exclusively expressed osteogenic miRNAs in SF-BGS, as well as overall enhanced osteogenic marker gene expression, as compared to the venous blood control group. These expression profiles were not seen in control samples, indicating that the derived material displays an osteogenic profile. It may therefore be a promising tool to generate a BGS or graft extender when needed.

MicroRNAs in Aseptic Loosening of Prosthesis: Pathophysiology and Potential Therapeutic Approaches

Objectives

Aseptic loosening (AL) is one of the leading causes of total joint arthroplasty (TJA) revision. Discovering the roles of microRNAs (miRNA/miR) in ontogenesis and osteolysis has attracted more attention to diagnosing and treating bone disorders. This review aimed to summarize miRNA biogenesis and describe the involvement of miRNAs in AL of implants.

Methods

A detailed search was carried out on scientific search engines, including Google Scholar, Web of Science, and PubMed, to find appropriate papers related to subjects. The search process was performed using the following keywords: "Implant", "miRNAs", "Wear particles", "Osteoclasts", "Total joint replacement", and "Osteolytic diseases".

Results

miRNAs play an essential role in the regulation of gene expression. AL is associated with several pathologic properties, including wear particle-induced persistent inflammatory response, unbalanced osteoclastogenesis, abnormal osteoblast differentiation, and maturation. Recent researches have revealed that these pathological events are closely associated with miRNA deregulation, confirming the relationship between miRNA and AL of prostheses.

Conclusion

With the results of the new approaches to target miRNA, the essential role of miRNA is further defined. Understanding the mechanisms of miRNAs and related signaling pathways in the pathophysiology of AL will help scientists illuminate novel therapeutic strategies and specific targeted drugs.

MicroRNA-138: an emerging regulator of skeletal development, homeostasis, and disease

Noncoding microRNAs are powerful epigenetic regulators of cellular processes by their ability to target and suppress expression of numerous protein-coding mRNAs. This multitargeting function is a unique and complex feature of microRNAs. It is now well-described that microRNAs play important roles in regulating the development and homeostasis of many cell/tissue types, including those that make up the skeletal system. In this review, we focus on microRNA-138 (miR-138) and its effects on regulating bone and cartilage cell differentiation and function. In addition to its reported role as a tumor suppressor, miR-138 appears to function as an inhibitor of osteoblast differentiation. This review provides additional information on studies that have attempted to alter miR-138 expression in vivo as a means to dampen ectopic calcification or alter bone mass. However, a review of the published literature on miR-138 in cartilage reveals a number of contradictory and inconclusive findings with respect to regulating chondrogenesis and chondrocyte catabolism. This highlights the need for more research in understanding the role of miR-138 in cartilage biology and disease. Interestingly, a number of studies in other systems have reported miR-138-mediated effects in dampening inflammation and pain responses. Future studies will reveal if a multifunctional role of miR-138 involving suppression of ectopic bone, inflammation, and pain will be beneficial in skeletal conditions such as osteoarthritis and heterotopic ossification.

Circulating miRNA expression in extracellular vesicles is associated with specific injuries after multiple trauma and surgical invasiveness

Introduction

Two trauma treatment principles are Early Total Care (ETC), and Damage Control Orthopedics (DCO). Cellular mechanisms that underlie the connection between treatment type, its systemic effects, and tissue regeneration are not fully known. Therefore, this study aimed to: 1) profile microRNA (miRNA) expression in plasma derived Extracellular Vesicles (EVs) from a porcine multiple trauma model at different timepoints, comparing two surgical treatments; and 2) determine and validate the miRNA's messengerRNA (mRNA) targets.

Methods

The porcine multiple trauma model consisted of blunt chest trauma, liver laceration, bilateral femur fractures, and controlled haemorrhagic shock. Two treatment groups were defined, ETC (n=8), and DCO (n=8). Animals were monitored under Intensive Care Unit-standards, blood was sampled at 1.5, 2.5, 24, and 72 hours after trauma, and EVs were harvested from plasma. MiRNAs were analysed using quantitative Polymerase Chain Reaction arrays. MRNA targets were identified in silico and validated in vivo in lung and liver tissue.

Results

The arrays showed distinct treatment specific miRNA expression patterns throughout all timepoints, and miRNAs related to the multiple trauma and its individual injuries. EV-packed miRNA expression in the ETC group was more pro-inflammatory, indicating potentially decreased tissue regenerative capacities in the acute post-traumatic phase. In silico target prediction revealed several overlapping mRNA targets among the identified miRNAs, related to inflammation, (pulmonary) fibrosis, and Wnt-signalling. These were, among others, A Disintegrin and Metalloproteinase domain-containing protein 10, Collagen Type 1 Alpha 1 Chain, Catenin Beta Interacting Protein 1, and Signal Transducers and Activators of Transcription 3. Validation of these mRNA targets in the lung showed significant, treatment specific deregulations which matched the expression of their upstream miRNAs. No significant mRNA deregulations were observed in the liver.

Discussion

This study showed treatment specific, EV-packed miRNA expression patterns after trauma that correlated with mRNA expressions in the lungs, target organs over distance. A systemic response to the increased surgical trauma in the ETC group was identified, with various miRNAs associated with injuries from the trauma model, and involved in (systemic) inflammation, tissue regeneration. EV-transported miRNAs demonstrated a clear role in multiple trauma, warranting further research into tissue-tissue talk and therapeutic applications of EVs after trauma.

MiRNAs as Potential Regulators of Enthesis Healing: Findings in a Rodent Injury Model

MicroRNAs (miRNAs) are short non-coding RNA sequences with the ability to inhibit the expression of a target mRNA at the post-transcriptional level, acting as modulators of both the degenerative and regenerative processes. Therefore, these molecules constitute a potential source of novel therapeutic tools. In this study, we investigated the miRNA expression profile that presented in enthesis tissue upon injury. For this, a rodent enthesis injury model was developed by creating a defect at a rat's patellar enthesis. Following injury, explants were collected on days 1 (n = 10) and 10 (n = 10). Contra lateral samples (n = 10) were harvested to be used for normalization. The expression of miRNAs was investigated using a "Fibrosis" pathway-focused miScript qPCR array. Later, target prediction for the aberrantly expressed miRNAs was performed by means of the Ingenuity Pathway Analysis, and the expression of mRNA targets relevant for enthesis healing was confirmed using qPCRs. Additionally, the protein expression levels of collagens I, II, III, and X were investigated using Western blotting. The mRNA expression pattern of EGR1, COL2A1, RUNX2, SMAD1, and SMAD3 in the injured samples indicated their possible regulation by their respective targeting miRNA, which included miR-16, -17, -100, -124, -133a, -155 and -182. Furthermore, the protein levels of collagens I and II were reduced directly after the injury (i.e., day 1) and increased 10 days post-injury, while collagens III and X showed the opposite pattern of expression.

Emerging role of mesenchymal stem/stromal cells (MSCs) and MSCs-derived exosomes in bone- and joint-associated musculoskeletal disorders: a new frontier

Exosomes are membranous vesicles with a 30 to 150 nm diameter secreted by mesenchymal stem/stromal cells (MSCs) and other cells, such as immune cells and cancer cells. Exosomes convey proteins, bioactive lipids, and genetic components to recipient cells, such as microRNAs (miRNAs). Consequently, they have been implicated in regulating intercellular communication mediators under physiological and pathological circumstances. Exosomes therapy as a cell-free approach bypasses many concerns regarding the therapeutic application of stem/stromal cells, including undesirable proliferation, heterogeneity, and immunogenic effects. Indeed, exosomes have become a promising strategy to treat human diseases, particularly bone- and joint-associated musculoskeletal disorders, because of their characteristics, such as potentiated stability in circulation, biocompatibility, low immunogenicity, and toxicity. In this light, a diversity of studies have indicated that inhibiting inflammation, inducing angiogenesis, provoking osteoblast and chondrocyte proliferation and migration, and negative regulation of matrix-degrading enzymes result in bone and cartilage recovery upon administration of MSCs-derived exosomes. Notwithstanding, insufficient quantity of isolated exosomes, lack of reliable potency test, and exosomes heterogeneity hurdle their application in clinics. Herein, we will deliver an outline respecting the advantages of MSCs-derived exosomes-based therapy in common bone- and joint-associated musculoskeletal disorders. Moreover, we will have a glimpse the underlying mechanism behind the MSCs-elicited therapeutic merits in these conditions.

Molecular mechanisms of exercise contributing to tissue regeneration

Physical activity has been known as an essential element to promote human health for centuries. Thus, exercise intervention is encouraged to battle against sedentary lifestyle. Recent rapid advances in molecular biotechnology have demonstrated that both endurance and resistance exercise training, two traditional types of exercise, trigger a series of physiological responses, unraveling the mechanisms of exercise regulating on the human body. Therefore, exercise has been expected as a candidate approach of alleviating a wide range of diseases, such as metabolic diseases, neurodegenerative disorders, tumors, and cardiovascular diseases. In particular, the capacity of exercise to promote tissue regeneration has attracted the attention of many researchers in recent decades. Since most adult human organs have a weak regenerative capacity, it is currently a key challenge in regenerative medicine to improve the efficiency of tissue regeneration. As research progresses, exercise-induced tissue regeneration seems to provide a novel approach for fighting against injury or senescence, establishing strong theoretical basis for more and more "exercise mimetics." These drugs are acting as the pharmaceutical alternatives of those individuals who cannot experience the benefits of exercise. Here, we comprehensively provide a description of the benefits of exercise on tissue regeneration in diverse organs, mainly focusing on musculoskeletal system, cardiovascular system, and nervous system. We also discuss the underlying molecular mechanisms associated with the regenerative effects of exercise and emerging therapeutic exercise mimetics for regeneration, as well as the associated opportunities and challenges. We aim to describe an integrated perspective on the current advances of distinct physiological mechanisms associated with exercise-induced tissue regeneration on various organs and facilitate the development of drugs that mimics the benefits of exercise.

Epigenetic Alterations in Sports-Related Injuries

It is a well-known fact that physical activity benefits people of all age groups. However, highly intensive training, maladaptation, improper equipment, and lack of sufficient rest lead to contusions and sports-related injuries. From the perspectives of sports professionals and those performing regular–amateur sports activities, it is important to maintain proper levels of training, without encountering frequent injuries. The bodily responses to physical stress and intensive physical activity are detected on many levels. Epigenetic modifications, including DNA methylation, histone protein methylation, acetylation, and miRNA expression occur in response to environmental changes and play fundamental roles in the regulation of cellular activities. In the current review, we summarise the available knowledge on epigenetic alterations present in tissues and organs (e.g., muscles, the brain, tendons, and bones) as a consequence of sports-related injuries. Epigenetic mechanism observations have the potential to become useful tools in sports medicine, as predictors of approaching pathophysiological alterations and injury biomarkers that have already taken place.

Alcohol-induced inhibition of bone formation and neovascularization contributes to the failure of fracture healing via the miR-19a-3p/FOXF2 axis

Aims

Alcoholism is a well-known detrimental factor in fracture healing. However, the underlying mechanism of alcohol-inhibited fracture healing remains poorly understood.

Methods

MicroRNA (miR) sequencing was performed on bone mesenchymal stem cells (BMSCs). The effects of alcohol and miR-19a-3p on vascularization and osteogenic differentiation were analyzed in vitro using BMSCs and human umbilical vein endothelial cells (HUVECs). An in vivo alcohol-fed mouse model of femur fracture healing was also established, and radiological and histomorphometric analyses were used to evaluate the role of miR-19a-3p. The binding of miR-19a-3p to forkhead box F2 (FOXF2) was analyzed using a luciferase reporter assay.

Results

miR-19a-3p was identified as one of the key regulators in the osteogenic differentiation of BMSCs, and was found to be downregulated in the alcohol-fed mouse model of fracture healing. In vitro, miR-19a-3p expression was downregulated after ethanol administration in both BMSCs and HUVECs. Vascularization and osteogenic differentiation were independently suppressed by ethanol and reversed by miR-19a-3p. In addition, the luciferase reporter assay showed that FOXF2 is the direct binding target of miR-19a-3p. In vivo, miR-19a-3p agomir stimulated callus transformation and improved the alcohol-impaired fracture healing.

Conclusion

This study is the first to demonstrate that the miR-19a-3p/FOXF2 axis has a pivotal role in alcohol-impaired fracture healing, and may be a potential therapeutic target.

Cite this article: Bone Joint Res 2022;11(6):386–397.