Long noncoding RNA H19 accelerates tenogenic differentiation by modulating miR-140-5p/VEGFA signaling

Epigenetic mechanisms in stem cell therapies for achilles tendinopathy

Achilles tendinopathy (AT) is a chronic degenerative tendinopathy that affects people's daily lives. Multiple clinical studies have found that current conservative treatments fail to promote quality tendon healing. Recent studies have found that stem cell therapy can target pathophysiological changes in the tendon by replenishing tendon-derived cells, promoting extracellular matrix (ECM) remodeling, and modulating the inflammatory response to improve the microenvironment of Achilles tendon regeneration. And epigenetic modifications play an important role in stem cell fate determination and function. In this review, we provided a brief overview of the biological properties of relevant stem cells. The influence of epigenetic modifications on stem cell proliferation, differentiation, and immune regulatory function in the treatment of AT was also explored. We focused on gene regulatory mechanisms controlled by DNA methylation, histones and non-coding RNAs including microRNAs, circRNAs and long non-coding RNAs. We also discuss the current challenges faced by stem cell therapies in treating AT and their potential solutions. Further research in this area will provide a more comprehensive epigenetic explanation for stem cell therapy for AT, leading to the development of stable, safe and effective stem cell therapies.

Platelet-rich plasma-derived exosomes promote rotator cuff tendon-bone healing

BACKGROUND

Rotator cuff tear (RCT) is the most common type of shoulder joint injury, platelet-rich plasma-derived exosomes (PRP-exos) are highly promising in tissue repair and regeneration. The purpose of this study was to determine the function of PRP-exos in rotator cuff tendon-bone healing.

METHODS

PRP-exos were isolated from the rabbit whole blood by differential ultracentrifugation and characterized through transmission electron microscopy assay, nanoparticle tracking analysis, and western blotting. Alkaline phosphatase and Von Kossa staining were used to show tendon-derived stem cell (TDSC) differentiation. RT-qPCR and western blotting were performed to detect COL II, SOX-9, and TIMP-1. To determine the therapeutic effects of PRP-exos in vivo. Thirty New Zealand white rabbits were divided into control, model, and PRP-exos groups. The RCT animal model was constructed. The changes in tendon-bone tissue were determined by HE staining. Contents of COL-II, SOX-9, and TIMP-1 were determined by immunohistochemistry staining.

RESULTS

PRP-exos were successfully isolated from rabbit blood. PRP-exos promoted TDSC proliferation and differentiation and also induced tendon-specific markers COL II, SOX-9, and TIMP-1 production. In vivo study revealed that PRP-exos promoted early healing of injured tendons. Rabbits treated with PRP-exos had better tissue arrangement in the tear site. Additionally, the contents of COL II, SOX-9, and TIMP-1 were also increased in the RCT rabbit model after PRP-exos treatment.

CONCLUSIONS

PRP-exos enhanced tendon-bone healing by promoting TDSC proliferation and differentiation. This finding indicates that PRP-exos can serve as a promising strategy to treat rotator cuff tendon-bone healing.

Long non-coding RNA small nucleolar RNA host gene 29 drives chronic myeloid leukemia progression via microRNA-483-3p/Casitas B-lineage Lymphoma axis-mediated activation of the phosphoinositide 3-kinase/Akt pathway

The aberrant expression of the long non-coding RNA (lncRNA) Small Nucleolar RNA Host Gene 29 (SNHG29) has been associated with various human cancers. However, the role of SNHG29 in chronic myeloid leukemia (CML) remains elusive. Therefore, this study aimed to investigate the function of SNHG29 in CML and unveil its potential underlying mechanisms. Herein, peripheral blood samples from 44 CML patients and 17 healthy subjects were collected. The expressions of SNHG29, microRNA-483-3p (miR-483-3p), and Casitas B-lineage Lymphoma (CBL) were measured using quantitative polymerase chain reaction (qPCR) or Western Blot. Cell viability, apoptosis, and cell cycle progression were evaluated using the Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine incorporation, and flow cytometry, respectively. Western Blot analysis was employed to assess protein expressions related to cellular proliferation, apoptosis, and oncogenesis. RNA immunoprecipitation and dual-luciferase reporter assays were utilized to verify the interactions among SNHG29, miR-483-3p, and CBL. SNHG29 was significantly overexpressed in both blood samples of CML patients and CML cell lines. In CML, increased expression of SNHG29 was positively correlated with clinical staging, and patients with high SNHG29 expression had poorer survival outcomes. Functionally, knocking down SNHG29 effectively inhibited CML cell proliferation and promoted apoptosis. Mechanistically, SNHG29 acted as a competing endogenous RNA for miR-483-3p to modulate CBL expression, thereby activating the Phosphoinositide 3-Kinase/Akt signaling pathway and mediating CML progression. In summary, these findings reveal that SNHG29 promotes tumorigenesis in CML, offering a potential therapeutic strategy for CML treatment.

Tenogenic differentiation of human tendon-derived stem cells induced by long non-coding RNA LINCMD1 via miR-342-3p/EGR1 axis

BACKGROUND

Tendon-derived stem cells (TDSCs) are proposed as a potential cell-seed for the treatment of tendon injury due to their tenogenic differentiation potential. In this work, we defined the action of long non-coding RNA (lncRNA) muscle differentiation 1 (LINCMD1) in tenogenic differentiation of human TDSCs (hTDSCs).

METHODS

Quantitative real-time PCR (qRT-PCR) was used to assess the levels of LINCMD1, microRNA (miR)-342-3p, and early growth response-1 (EGR1) mRNA. Cell proliferation was detected by the XTT colorimetric assay. Protein expression was quantified by western blot. hTDSCs were grown in an osteogenic medium to induce osteogenic differentiation, and the extent of osteogenic differentiation was assessed by Alizarin Red Staining (ARS). The activity of alkaline phosphatase (ALP) was measured by the ALP Activity Assay Kit. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-342-3p and LINCMD1 or EGR1.

RESULTS

Our results showed that enforced expression of LINCMD1 or suppression of miR-342-3p accelerated the proliferation and tenogenic differentiation and reduced osteogenic differentiation of hTDSCs. LINCMD1 regulated miR-342-3p expression by binding to miR-342-3p. EGR1 was identified as a direct and functional target of miR-342-3p, and knockdown of EGR1 reversed the effects of miR-342-3p suppression on cell proliferation and tenogenic and osteogenic differentiation. Furthermore, the miR-342-3p/EGR1 axis mediated the regulation of LINCMD1 on hTDSC proliferation and tenogenic and osteogenic differentiation.

CONCLUSION

Our study suggests the induction of LINCMD1 in tenogenic differentiation of hTDSCs through miR-342-3p/EGR1 axis.

MicroRNA expression changes in the development of rotator cuff tendon injuries

Traumatic or degenerative rotator cuff (RC) tendon injuries are a leading cause of persistent shoulder pain and reduction of mobility with associated disability and dysfunction, which require each year more than 250,000 surgical repairs in the United States. MicroRNAs (miRNAs) are small noncoding RNAs, that in the posttranscriptional phase lead to the development and function of tissues. The aim of this review was to identify miRNA expression changes in patients with RC pathologies and to determine their relevance as a potential novel diagnostic and potentially therapeutic tool for RC disorders. Various miRNAs seemed to be key regulators in the muscle architecture, determining several modifications in muscle atrophy, skeletal muscle mechanical adaptation, lipid accumulation, and fibrosis in the presence of RC tears. The search was executed using PubMed, Medline, Scopus, and Cochrane Central. We included studies written in English that evaluated the role of miRNA in diagnosis, physiopathology, and potential therapeutic application of RC tendon injuries. We included 11 studies in this review. Many miRNAs emerged as key regulators in the pathogenesis of RC tears, inflammation, and muscle fatty degeneration. In fact, they are involved in the regulation of myogenesis, inflammatory cytokines, metalloproteases expression, muscle adaptation, adipogenesis, fibrogenic factors, and extracellular matrix synthesis. The gene expression may be altered in the pathological processes of tendon lesions. Therefore, the knowledge of all the gene mechanisms underlying RC tendinopathy should be achieved with future diagnostic and clinical studies.

Pro-inflammatory activity of long noncoding RNA FOXD2-AS1 in Achilles tendinopathy

Achilles tendinopathy is a prevalent clinical problem that plagues athletes and general populations. Achilles tendon healing is a complex process, and so far, there is no successful long-term solution to Achilles tendinopathy in the field of microsurgery due to its poor natural regeneration ability. Limitations in understanding the pathogenesis of Achilles tendon development and Achilles tendon injury hinder clinical treatment developments. There is an increasing demand for innovative conservative treatments that can improve Achilles tendon injury. In this study, a Sprague-Dawley rat model of Achilles tendinopathy was established. Lentiviral vectors that interfere with the expression of FOXD2-AS1, miR-21-3p, or PTEN were injected every 3 days. Rats were euthanized after 3 weeks, and the effect of FOXD2-AS1, miR-21-3p, or PTEN on Achilles tendon healing was analyzed by histological observation, biomechanical test, and examinations of inflammatory factors and tendon markers. As measured, downregulating FOXD2-AS1 or upregulating miR-21-3p improved histological structure, suppressed inflammation, promoted the expression of tendon markers, and optimized the biomechanical properties of Achilles tendon. Upregulating PTEN was capable of reversing the promoting effect of inhibition of FOXD2-AS1 on Achilles tendon healing. As concluded, deficiency of FOXD2-AS1 accelerates the healing of Achilles tendon injury and improves tendon degeneration by regulating the miR-21-3p/PTEN axis and promoting the activation of the PI3K/AKT signaling pathway.

LncRNA H19 promotes tumor angiogenesis in smokers by targeting anti-angiogenic miRNAs

A key concept in drug discovery is the identification of candidate therapeutic targets such as long noncoding RNAs (lncRNAs) because of their extensive involvement in neoplasms, and impressionability by smoking. Induced by exposure to cigarette smoke, lncRNA H19 targets and inactivates miR-29, miR-30a, miR-107, miR-140, miR-148b, miR-199a and miR-200, which control the rate of angiogenesis by inhibiting BiP, DLL4, FGF7, HIF1A, HIF1B, HIF2A, PDGFB, PDGFRA, VEGFA, VEGFB, VEGFC, VEGFR1, VEGFR2 and VEGFR3. Nevertheless, these miRNAs are often dysregulated in bladder cancer, breast cancer, colorectal cancer, glioma, gastric adenocarcinoma, hepatocellular carcinoma, meningioma, non-small-cell lung carcinoma, oral squamous cell carcinoma, ovarian cancer, prostate adenocarcinoma and renal cell carcinoma. As such, the present perspective article seeks to establish an evidence-based hypothetical model of how a smoking-related lncRNA known as H19 might aggravate angiogenesis by interfering with miRNAs that would otherwise regulate angiogenesis in a nonsmoking individual.

VEGFA-Enriched Exosomes from Tendon-Derived Stem Cells Facilitate Tenocyte Differentiation, Migration, and Transition to a Fibroblastic Phenotype

Tendon-derived stem cells (TDSCs) play a vital role in repair of rotator cuff tear injuries by secreting paracrine proteins that regulate resident cell functions. Secreted exosomes may play a role in tendon injury repair by mediating intercellular communication; however, the detailed mechanisms by which TDSC-derived exosomes affect tenocyte development remain unknown. Here, we examined the effects of exosomes isolated from conditioned medium of TDSCs on tenocyte differentiation, migration, and transition to a fibroblastic phenotype in vitro. Successful isolation of exosomes from TDSCs was confirmed by high expression levels of CD81, CD63, CD9, and TSG101. Treatment with TDSC-derived exosomes promoted the growth and migration of cultured rat tenocytes, and increased the levels of the fibrosis markers collagen I, collagen III, scleraxis, tenascin C, and α-smooth muscle actin. Furthermore, vascular endothelial growth factor A (VEGFA) expression was higher in TDSC-derived exosomes than in TDSCs, and genetic knockdown of VEGFA suppressed the stimulatory effect of TDSC-derived exosomes on tenocyte development. Overall, these results demonstrate that VEGFA-enriched exosomes isolated from TDSCs promote differentiation and migration of cultured tenocytes and their transition to a fibroblastic phenotype. These data provide a new potential clinical treatment strategy for tendon injury.

Challenges and perspectives of tendon-derived cell therapy for tendinopathy: from bench to bedside

Tendon is composed of dense fibrous connective tissues, connecting muscle at the myotendinous junction (MTJ) to bone at the enthesis and allowing mechanical force to transmit from muscle to bone. Tendon diseases occur at different zones of the tendon, including enthesis, MTJ and midsubstance of the tendon, due to a variety of environmental and genetic factors which consequently result in different frequencies and recovery rates. Self-healing properties of tendons are limited, and cell therapeutic approaches in which injured tendon tissues are renewed by cell replenishment are highly sought after. Homologous use of individual’s tendon-derived cells, predominantly differentiated tenocytes and tendon-derived stem cells, is emerging as a treatment for tendinopathy through achieving minimal cell manipulation for clinical use. This is the first review summarizing the progress of tendon-derived cell therapy in clinical use and its challenges due to the structural complexity of tendons, heterogeneous composition of extracellular cell matrix and cells and unsuitable cell sources. Further to that, novel future perspectives to improve therapeutic effect in tendon-derived cell therapy based on current basic knowledge are discussed.

Advances in Stem Cell Therapies for Rotator Cuff Injuries

Rotator cuff injury is a common upper extremity musculoskeletal disease that may lead to persistent pain and functional impairment. Despite the clinical outcomes of the surgical procedures being satisfactory, the repair of the rotator cuff remains problematic, such as through failure of healing, adhesion formation, and fatty infiltration. Stem cells have high proliferation, strong paracrine action, and multiple differentiation potential, which promote tendon remodeling and fibrocartilage formation and increase biomechanical strength. Additionally, stem cell-derived extracellular vesicles (EVs) can increase collagen synthesis and inhibit inflammation and adhesion formation by carrying regulatory proteins and microRNAs. Therefore, stem cell-based therapy is a promising therapeutic strategy that has great potential for rotator cuff healing. In this review, we summarize the advances of stem cells and stem cell-derived EVs in rotator cuff repair and highlight the underlying mechanism of stem cells and stem cell-derived EVs and biomaterial delivery systems. Future studies need to explore stem cell therapy in combination with cellular factors, gene therapy, and novel biomaterial delivery systems.