Altered expression of SDF-1 and CXCR4 during fracture healing in diabetes mellitus

Osteogenic effect of low-intensity pulsed ultrasound on peri-implant bone: A systematic review and meta-analysis

Purpose This study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on promoting osseointegration around dental implants.Study selection A comprehensive search was performed on two databases, including MEDLINE (PubMed) and Web of Science to identify relevant studies published before June 1, 2022. Randomized controlled trials that met the inclusion criteria were selected for the study. The year of publication, study design, animal species, number of animals, number of implants, implant position, implant size, intervention, follow-up time, bone volume ratio (BV/TV), bone-implant contact ratio (BIC), and implant removal torque value (RTV) measurements, including mean and SD, were extracted.Results Ten randomized trials were included in this meta-analysis. The results showed that LIPUS significantly promoted osteogenesis around dental implants. Furthermore, in animal models of pre-existing diseases such as osteoporosis and diabetes, LIPUS had the same effect. The included data were divided into subgroups to explore the effects of different follow-up time, acoustic intensities, and frequencies. Results showed that higher acoustic intensities and frequencies significantly improve the osteogenic effects of LIPUS. There was some degree of heterogeneity owing to bias in the included studies. More high-quality randomized controlled trials are necessary in the future.Conclusions LIPUS can promote bone healing around dental implants and is an attractive option for edentulous patients, especially those with pre-existing diseases. Further clinical trials on the use of LIPUS in implant dentistry are warranted. Furthermore, future studies must pay more attention to acoustic intensity and frequency.

Genistein, a Soybean Isoflavone, Promotes Wound Healing by Enhancing Endothelial Progenitor Cell Mobilization in Rats with Hemorrhagic Shock

Severe trauma and hemorrhaging are often accompanied by delayed cutaneous wound healing. Soybean isoflavone is a natural phytoestrogen that has attracted great attention due to its protective effects against various injuries. Endothelial progenitor cells (EPCs) are precursor cells with directional differentiation characteristics. This study is to determine whether genistein (GEN), an isoflavone in soybean products, benefits wound healing in hemorrhagic shock (HS) rats by promoting EPC homing and to investigate the underlying mechanisms. In this study, it is found that GEN promotes skin wound healing in HS rats, which is due at least partly to the mobilization of endogenous EPCs to the injury site via angiotensin II (Ang-II), stromal cell-derived factor-1alpha (SDF-1α), and transforming growth factor beta(TGF-β) signaling.

Downregulation of miR-221-3p by LncRNA TUG1 Promoting the Healing of Closed Tibial Fractures in Mice

Objective

To probe into the effect of LncRNA TUG1 on the healing of closed tibial fracture in mice.

Methods

The closed tibial fracture model of mice was established, selecting the mouse osteoblast line MC3T3-E1, with the cells separated into four groups. The expression levels of TUG1 and miR-221-3p were determined by RT-qPCR analysis, with the targeting relationship between TUG1 and miR-221-3p authenticated by dual luciferase reporter (DLR) assay, detection of cell migration (CM) ability based on Transwell cell migration (TCM) assay, and cell proliferation (CP) acquired by cell counting kit-8 (CCK-8).

Results

Prediction results of the target gene by bioinformatics software showed that miR-221-3p had binding sites with the 3'-UTR of TUG1, and DLR assay authenticated the targeting relationship between LncRNA TUG1 and miR-221-3p. Downregulation of TUG1 inhibited osteoblast CP and CM and promoted osteoblast cell apoptosis (CA). Cell cycle analysis indicated that miR-221-3p provoked cell cycle arrest in G1 stage of MC3T3-E1 cells. The siLncRNA-NC group had higher anticyclin D1 and D3 levels than the siLncRNA TUG1 group, with a lower CA rate in the former, implying that miR-221-3p overexpression inhibited osteoblast CP and CM and LncRNA TUG1 inhibited CA. Downregulation of miR-221-3p partly reversed the retardation out of downregulating TUG1 on osteoblast CP and CM. Bcl-2 level was higher in the LncRNA TUG1 group compared to the siLncRNA TUG1 and miR-221-3p overexpression groups, with remarkably lower SDF-1 level in the miR-221-3p overexpression group than those in the control, miRNA-NC, and LncRNA TUG1 groups.

Conclusion

The downregulation of miR-221-3p by LncRNA TUG1 can promote the healing of closed tibial fractures in mice.

Low-intensity pulsed ultrasound (LIPUS) for stimulation of bone healing - A narrative review

The use of low intensity pulsed ultrasound (LIPUS) to accelerate the fracture repair process in humans was first reported by Xavier & Duarte in 1983 [1]. This success led to clinical trials and the 1994 approval of LIPUS in the United States for the accelerated healing of certain fresh fractures. LIPUS was approved in the US for the treatment of established non-unions in 2000, and is also approved around the world. In this article, we present relevant literature on the effect of LIPUS on bone healing in patients with acute fractures and non-unions and provide a molecular explanation for the effects of LIPUS on bone healing. Data on LIPUS accelerated fracture repair is controversial with many controlled studies showing a positive effect. However, the largest trial in acute tibial fractures stabilized with an intramedullary nail failed to show significant differences in accelerated healing and in functional outcomes. Uncontrolled data from prospective case series suggest a positive effect of LIPUS in non united fractures with healing rates of around 85%. Evaluation of results from studies, both positive and negative, has enabled an understanding that the patient population with potentially the greatest benefit from receiving LIPUS are those at-risk for fracture healing, e.g. diabetic & elderly patients. The elucidation of a pathway to activate the Rac-1 pathway by LIPUS might explain this beneficial effect. Overall, there is a strong need for further clinical trials, particularly for acute fractures at risk of progressing to non-union and in established non-unions including a comparison to the current standard of care.

Transcutaneous CO2 application accelerates fracture repair in streptozotocin-induced type I diabetic rats

INTRODUCTION

Diabetes mellitus (DM) negatively affects fracture repair by inhibiting endochondral ossification, chondrogenesis, callus formation, and angiogenesis. We previously reported that transcutaneous CO₂ application accelerates fracture repair by promoting endochondral ossification and angiogenesis. The present study aimed to determine whether CO₂ treatment would promote fracture repair in cases with type I DM.

RESEARCH DESIGN AND METHODS

A closed femoral shaft fracture was induced in female rats with streptozotocin-induced type I DM. CO₂ treatment was performed five times a week for the CO₂ group. Sham treatment, where CO₂ was replaced with air, was performed for the control group. Radiographic, histologic, genetic, and biomechanical measurements were taken at several time points.

RESULTS

Radiographic assessment demonstrated that fracture repair was induced in the CO₂ group. Histologically, accelerated endochondral ossification and capillary formation were observed in the CO₂ group. Immunohistochemical assessment indicated that early postfracture proliferation of chondrocytes in callus was enhanced in the CO₂ group. Genetic assessment results suggested that cartilage and bone formation, angiogenesis, and vasodilation were upregulated in the CO₂ group. Biomechanical assessment revealed enhanced mechanical strength in the CO₂ group.

CONCLUSIONS

Our findings suggest that CO₂ treatment accelerates fracture repair in type I DM rats. CO₂ treatment could be an effective strategy for delayed fracture repair due to DM.

Altered microRNA profile during fracture healing in rats with diabetes

Background

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that regulate gene expression. There is increasing evidence that some miRNAs are involved in the pathology of diabetes mellitus (DM) and its complications. We hypothesized that the functions of certain miRNAs and the changes in their patterns of expression may contribute to the pathogenesis of impaired fractures due to DM.

Methods

In this study, 108 male Sprague–Dawley rats were divided into DM and control groups. DM rats were created by a single intravenous injection of streptozotocin. Closed transverse femoral shaft fractures were created in both groups. On post-fracture days 5, 7, 11, 14, 21, and 28, miRNA was extracted from the newly generated tissue at the fracture site. Microarray analysis was conducted with miRNA samples from each group on post-fracture days 5 and 11. The microarray findings were validated by real-time polymerase chain reaction (PCR) analysis at each time point.

Results

Microarray analysis revealed that, on days 5 and 11, 368 and 207 miRNAs, respectively, were upregulated in the DM group, compared with the control group. The top four miRNAs on day 5 were miR-339-3p, miR451-5p, miR-532-5p, and miR-551b-3p. The top four miRNAs on day 11 were miR-221-3p, miR376a-3p, miR-379-3p, and miR-379-5p. Among these miRNAs, miR-221-3p, miR-339-3p, miR-376a-3p, miR-379-5p, and miR-451-5p were validated by real-time PCR analysis. Furthermore, PCR analysis revealed that these five miRNAs were differentially expressed with dynamic expression patterns during fracture healing in the DM group, compared with the control group.

Conclusions

Our findings will aid in understanding the pathology of impaired fracture healing in DM and may support the development of molecular therapies using miRNAs for the treatment of impaired fracture healing in patients with DM.

Chronic Intermittent Hypobaric Hypoxia Enhances Bone Fracture Healing

The effect of chronic intermittent hypobaric hypoxia (CIHH) on bone fracture healing is not elucidated. The present study aimed to investigate the role of CIHH on bone fracture healing and the mechanism. The Sprague-Dawley rats were randomly divided into the CIHH group and control group and monitored for 2, 4, or 8 weeks after femoral fracture surgery. Bone healing efficiency was significantly increased in the CIHH group as evidenced by higher high-density bone volume fractions, higher bone mineral density, higher maximum force, and higher stiffness. Histologically, the CIHH group exhibited superior bone formation, endochondral ossification, and angiogenic ability compared with the control group. The expression of HIF-1α and its downstream signaling proteins VEGF, SDF-1/CXCR4 axis were increased by the CIHH treatment. Moreover, the expression of RUNX2, osterix, and type I collagen in the callus tissues were also up-regulated in the CIHH group. In conclusion, our study demonstrated that CIHH treatment improves fracture healing, increases bone mineral density, and increases bone strength via the activation of HIF-1α and bone production-related genes.