scholarly journals Melatonin restores osteoporosis-impaired osteogenic potential of bone marrow mesenchymal stem cells and alleviates bone loss through the HGF/PTEN/Wnt/β-catenin axis

2021 ◽  
Vol 12 ◽  
pp. 204062232199568
Author(s):  
Jun Zhang ◽  
Guoliang Jia ◽  
Pan Xue ◽  
Zhengwei Li
Keyword(s):  
Bone Marrow ◽  
Bone Loss ◽  
Osteogenic Differentiation ◽  
Cell Counting ◽  
Luciferase Reporter ◽  
Osteogenic Potential ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
Micro Computed Tomography ◽  
Alizarin Red

Background: Previous studies reported that melatonin exerts its effect on mesenchymal stem cell (MSC) survival and differentiation into osteogenic and adipogenic lineage. In the current study we aimed to explore the effect of melatonin on osteoporosis and relevant mechanisms. Methods: Real-time qualitative polymerase chain reaction (RT-qPCR) and Western blot analysis were conducted to determine expression of HGF, PTEN, and osteoblast differentiation-related genes in ovariectomy (OVX)-induced osteoporosis mice and the isolated bone marrow MSCs (BMSCs). Pre-conditioning with melatonin (1 μmol/l, 10 μmol/l and 100 μmol/l) was carried out in OVX mice BMSCs. Bone microstructure was analyzed using micro-computed tomography and the contents of alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase 5b (TRAP5b) were detected by enzyme-linked immunosorbent assay in serum. BMSC proliferation was measured by cell-counting kit (CCK)-8 assay. Alizarin red S (ARS) staining and ALP activity assay were performed to assess BMSC mineralization and calcification. The activity of the Wnt/β-catenin pathway was evaluated by dual-luciferase reporter assay. Results: Melatonin prevented bone loss in OVX mice. Melatonin increased ALP expression and reduced TRAP5b expression. HGF and β-catenin were downregulated, while PTEN was upregulated in the femur of OVX mice. Melatonin elevated HGF expression and then stimulated BMSC proliferation and osteogenic differentiation. Additionally, HGF diminished the expression of PTEN, resulting in activated Wnt/β-catenin pathway both in vitro and in vivo. Furthermore, melatonin was shown to ameliorate osteoporosis in OVX mice via the HGF/ PTEN/ Wnt/β-catenin axis. Conclusion: Melatonin could potentially enhance osteogenic differentiation of BMSCs and retard bone loss through the HGF/ PTEN/ Wnt/β-catenin axis.

scholarly journals Crosstalk between adipocytes and M2 macrophages compensates for osteopenic phenotype in the Lrp5-deficient mice

2020 ◽  
pp. 153537022097232
Author(s):  
Lisha Li ◽  
Xuemin Qiu ◽  
Na Zhang ◽  
Yan Sun ◽  
Yan Wang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Wnt Signaling ◽  
Macrophage Polarization ◽  
Myeloid Cells ◽  
Osteogenic Potential ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tartrate Resistant Acid Phosphatase ◽  
M2 Macrophage ◽  
M2 Macrophages ◽  
Alizarin Red

A loss-of-function mutation in the Lrp5 gene in mice leads to a low bone mass disorder due to the inhibition of the canonical Wnt signaling pathway; however, the role of bone marrow microenvironment in mice with this mutation remains unclear. In this study, we evaluated proliferation and osteogenic potential of mouse osteoblasts using the MTT assay and Alizarin red staining. The levels of alkaline phosphatase, tartrate-resistant acid phosphatase, and adiponectin in culture supernatants were measured using the enzyme-linked immunosorbent assay. Osteoclast bone resorbing activity was evaluated by toluidine staining and the number and area of bone resorption pits were determined. We observed increased osteogenesis in osteoblasts co-cultured with the BM-derived myeloid cells compared to the osteoblasts cultured alone. Mice with global Lrp5 deletion had a relatively higher bone density compared to the mice carrying osteoblast/osteocyte-specific Lrp5 deletion. An increased frequency of M2 macrophages and reduced expression of inflammatory cytokines were detected in the myeloid cells derived from the bone marrow of mice with global Lrp5 deletion. Higher adipogenic potential and elevated levels of adiponectin in the global Lrp5 deletion mice contributed to the preferential M2 macrophage polarization. Here, we identified a novel systemic regulatory mechanism of bone formation and degradation in mice with global Lrp5 deletion. This mechanism depends on a crosstalk between the adipocytes and M2 macrophages in the bone marrow and is responsible for partly rescuing osteopenia developed as a result of decreased Wnt signaling.

scholarly journals Melatonin promotes bone marrow mesenchymal stem cell osteogenic differentiation and prevents osteoporosis development through modulating circ_0003865 that sponges miR-3653-3p

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xudong Wang ◽  
Taiqiu Chen ◽  
Zhihuai Deng ◽  
Wenjie Gao ◽  
Tongzhou Liang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Osteogenic Differentiation ◽  
Luciferase Reporter ◽  
Specific Gene ◽  
Biological Processes ◽  
Alizarin Red ◽  
Qrt Pcr ◽  
Dual Luciferase Reporter Assay

Abstract Background Little is known about the implications of circRNAs in the effects of melatonin (MEL) on bone marrow mesenchymal stem cell (BMSC) osteogenic differentiation and osteoporosis (OP) progression. The aim of our study was to investigate circRNAs in MEL-regulated BMSC differentiation and OP progression. Methods BMSC osteogenic differentiation was measured by qRT-PCR, western blot (WB), Alizarin Red, and alkaline phosphatase (ALP) staining. Differential circRNA and mRNA profiles of BMSCs treated by MEL were characterized by deep sequencing, followed by validation using RT-PCR, Sanger sequencing, and qRT-PCR. Silencing and overexpression of circ_0003865 were conducted for functional investigations. The sponged microRNAs and targeted mRNAs were predicted by bioinformatics and validated by qRT-PCR, RNA pull-down, and dual-luciferase reporter assay. The function of miR-3653-3p and circ_0003865/miR-3653-3p/growth arrest-specific gene 1 (GAS1) cascade was validated for the osteogenic differentiation of BMSCs by CCK-8, qRT-PCR, WB, Alizarin Red, and ALP staining. The effects of circ_0003865 on OP development were tested in murine OP model. Results MEL promoted osteogenic differentiation of BMSCs. RNA sequencing revealed significant alterations in circRNA and mRNA profiles associated with multiple biological processes and signaling pathways. Circ_0003865 expression in BMSCs was significantly decreased by MEL treatment. Silencing of circ_0003865 had no effect on proliferation while promoted osteogenic differentiation of BMSCs. Overexpression of circ_0003865 abrogated the promotion of BMSC osteogenic differentiation induced by MEL, but proliferation of BMSCs induced by MEL had no change whether circ_0003865 was overexpression or not. Furthermore, circ_0003865 sponged miR-3653-3p to promote GAS1 expression in BMSCs. BMSC osteogenic differentiation was enhanced by miR-3653-3p overexpression while BMSC proliferation was not affected. By contrast, miR-3653-3p silencing mitigated the promoted BMSC osteogenic differentiation caused by circ_0003865 silencing, but had no effect on proliferation. Finally, circ_0003865 silencing repressed OP development in mouse model. Conclusion MEL promotes BMSC osteogenic differentiation and inhibits OP pathogenesis by suppressing the expression of circ_0003865, which regulates GAS1 gene expression via sponging miR-3653-3p.

scholarly journals MicroRNA-346-5p Regulates Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells by Inhibiting Transmembrane Protein 9

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Yicai Zhang ◽  
Yi Sun ◽  
Jinlong Liu ◽  
Yu Han ◽  
Jinglong Yan
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Osteogenic Differentiation ◽  
Protein Level ◽  
Molecular Mechanisms ◽  
Transmembrane Protein ◽  
Luciferase Reporter ◽  
Alizarin Red ◽  
Protein Levels

The molecular mechanisms how bone marrow-derived mesenchymal stem cells (BMSCs) differentiate into osteoblast need to be investigated. MicroRNAs (miRNAs) contribute to the osteogenic differentiation of BMSCs. However, the effect of miR-346-5p on osteogenic differentiation of BMSCs is not clear. This study is aimed at elucidating the underlying mechanism by which miR-346-5p regulates osteogenic differentiation of human BMSCs. Results of alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining indicated that upregulation of miR-346-5p suppressed osteogenic differentiation of BMSCs, whereas downregulation of miR-346-5p enhanced this process. The protein levels of the osteoblastic markers Osterix and Runt-related transcription factor 2 (Runx2) were decreased in cells treated with miR-346-5p mimic at day 7 and day 14 after being differentiated. By contrast, downregulation of miR-346-5p elevated the protein levels of Osterix and Runx2. Moreover, a dual-luciferase reporter assay revealed that Transmembrane Protein 9 (TMEM9) was a target of miR-346-5p. In addition, the Western Blot results demonstrated that the TMEM9 protein level was significantly reduced by the miR-346-5p mimic whereas downregulation of miR-346-5p improved the protein level of TMEM9. These results together demonstrated that miR-346-5p served a key role in BMSC osteogenic differentiation of through targeting TMEM9, which may provide a novel target for clinical treatments of bone injury.

scholarly journals Polypeptides IGF-1C and P24 synergistically promote osteogenic differentiation of bone marrow mesenchymal stem cells in vitro through the p38 and JNK signaling pathways

2021 ◽  
Author(s):  
Gaoying Ran ◽  
Wei Fang ◽  
Lifang Zhang ◽  
Yuting Peng ◽  
Jiatong Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Osteogenic Differentiation ◽  
Bone Morphogenetic Protein 2 ◽  
Cell Counting ◽  
Signal Pathways ◽  
Alizarin Red ◽  
Alp Activity ◽  
Marrow Mesenchymal Stem Cells

Objectives: Insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein 2 (BMP-2) both promote osteogenesis of bone marrow mesenchymal stem cells (BMSCs). IGF-1C, the C domain peptide of IGF-1, and P24, a BMP-2-derived peptide, both have similar biological activities as their parent growth factors. This study aimed to investigate the effects and their mechanisms of polypeptides IGF-1C and P24 on the osteogenic differentiation of BMSCs. Methods: The optimum concentrations of IGF-IC and P24 were explored. The effects of the two polypeptides on the proliferation and osteogenic differentiation of BMSCs were examined using the Cell Counting Kit-8 (CCK-8), Alkaline phosphatase (ALP) staining, ALP activity assay, alizarin red S staining, qPCR, and western blotting. In addition, specific pathway inhibitors were utilized to explore whether p38 and JNK pathways were involved in this process. Results: The optimal concentrations of action were both 50 g/ml. IGF-1C and P24 synergistically promoted the proliferation of BMSCs, increased ALP activity and the formation of calcified nodules and upregulated the mRNA and protein levels of osterix (Osx), runt-related transcription factor 2 (Runx2), and osteocalcin (Ocn), phosphorylation level of p38 and JNK proteins also improved. Inhibition of the pathways significantly reduced the activation of p38 and JNK, blocked the expression of Runx2 while inhibiting ALP activity and the formation of calcified nodules. Conclusions: These findings suggest IGF-1C and P24 synergistically promote the osteogenesis of BMSCs through activation of p38 and JNK signal pathways.

scholarly journals MicroRNA-409-3p promotes osteoblastic differentiation via activation of Wnt/β-catenin signaling pathway by targeting SCAI

2020 ◽  
Author(s):  
Nan Chen ◽  
Hao Yang ◽  
Lijun Song ◽  
Hua Li ◽  
Yi Liu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Osteogenic Differentiation ◽  
Signaling Pathway ◽  
Quantitative Polymerase Chain Reaction ◽  
Osteoblastic Differentiation ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Complementary Sequence ◽  
Alizarin Red ◽  
Gene Assay

Osteogenic differentiation is an important process of new bone formation, miR-409-3p has been reported to be upregulated in osteogenic differentiation of human bone marrow mesenchymal stem cells (MSCs). To investigate the regulatory effect of miR-409-3p on osteogenic differentiation of MSCs and its molecular mechanism, the expression of miR-409-3p in osteoblast (HCO) and bone marrow-derived MSCs (MSC-A, MSC-B, MSC-U) were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The binding of miR-409-3p to SCAI in MSC-B was investigated by dual-luciferase reporter gene assay. MSC-B were selected to transfect with miR-409-3p analog/complementary sequence (cs), miR-409-3p analog + SCAI and miR-409-3p cs + small interfering (si)-SCAI, as well as control, respectively. The alkaline phosphatase activity, alizarin red staining, and the expression of osteogenic markers in MSC-B during osteoblastic differentiation were tested by RT-qPCR and Western blotting, respectively. The Wnt/β-catenin pathway was inhibited by dickkopf-related protein 1 to get the roles of miR-409-3p during the osteoblastic differentiation of MSC-B when transfected with miR-409-3p analog. The expression of miR-409-3p in HCO was higher than that in these three MSCs, showing an increasing time-dependent trend on the 0 and 21th day of osteoblastic differentiation. MiR-409-3p directly regulated SCAI by targeting SCAI 3′UTR. Further, miR-409-3p suppressed SCAI expression, but SCAI upregulation suppressed the osteoblastic differentiation, as well as reduced the relative mRNA/protein expression of Wnt/β-catenin signaling pathway-related genes. Importantly, disruption of Wnt signaling also blocked miR-409-3p induced osteoblastic differentiation of MSCs. Therefore, miR-409-3p promotes osteoblastic differentiation through the activation of the Wnt/β-catenin pathway by downregulating SCAI expression.

scholarly journals MicroRNA Hsa-Let-7b Regulates the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Targeting CTHRC1

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Lin Fu ◽  
Na Li ◽  
Yu Ye ◽  
Xiaying Ye ◽  
Tong Xiao ◽  
...  
Keyword(s):  
Stem Cells ◽  
Osteogenic Differentiation ◽  
Periodontal Ligament ◽  
Cell Counting ◽  
Luciferase Reporter ◽  
Periodontal Ligament Stem Cells ◽  
Alizarin Red ◽  
Proliferation Ability ◽  
Polymerase Chain ◽  
Dual Luciferase Reporter Assay

Let-7 miRNA family has been proved as a key regulator of mesenchymal stem cells’ (MSCs’) biological features. However, whether let-7b could affect the differentiation or proliferation of periodontal ligament stem cells (PDLSCs) is still unknown. Here, we found that the expression of hsa-let-7b was visibly downregulated after mineralization induction of PDLSCs. After transfected with hsa-let-7b mimics or inhibitor reagent, the proliferation ability of PDLSCs was detected by cell counting kit-8 (CCK-8), flow cytometry, and 5-ethynyl-2-deoxyuridine (EdU) assay. On the other hand, the osteogenic differentiation capacity was detected by alkaline phosphatase (ALP) staining and activity, alizarin red staining, Western blot, and quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). We verified that hsa-let-7b did not significantly impact the proliferation ability of PDLSCs, but it could curb the osteogenic differentiation of PDLSCs. Besides, we predicted CTHRC1 acts as the downstream gene of hsa-let-7b to affect this process. Moreover, the combination of CTHRC1 and hsa-let-7b was verified by dual luciferase reporter assay. Our results demonstrated that the osteogenic differentiation of PDLSCs was enhanced after inhibiting hsa-let-7b, while was weakened after cotransfection with Si-CTHRC1. Collectively, hsa-let-7b can repress the osteogenic differentiation of PDLSCs by regulating CTHRC1.

scholarly journals Melatonin Promotes Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation and Prevents Osteoporosis Development Through Modulating circ_0003865 that Sponges miR-3653-3p

2020 ◽  
Author(s):  
Xudong Wang ◽  
Taiqiu Chen ◽  
Zhihuai Deng ◽  
Wenjie Gao ◽  
Tongzhou Liang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Osteogenic Differentiation ◽  
Luciferase Reporter ◽  
Specific Gene ◽  
Biological Processes ◽  
Alizarin Red ◽  
Qrt Pcr ◽  
Dual Luciferase Reporter Assay

Abstract Background: To investigate circRNAs in Melatonin (MEL)-regulated bone marrow mesenchymal stem cell (BMSC) differentiation and osteoporosis.Methods: BMSC osteogenic differentiation was measured by qRT-PCR, western blot (WB), Alizarin Red and alkaline phosphatase (ALP) staining. Differential circRNA and mRNA profiles of BMSCs treated by MEL were characterized by deep sequencing, followed by validation using RT-PCR, Sanger sequencing, and qRT-PCR. Silencing and overexpression of circ_0003865 were conducted for functional investigations. The sponged microRNAs and targeted mRNAs were predicted by bioinformatics and validated by qRT-PCR, RNA pull-down, and dual-luciferase reporter assay. The function of miR-3653-3p and circ_0003865/miR-3653-3p/growth arrest-specific gene 1 (GAS1) cascade were validated for the osteogenic differentiation of BMSCs by qRT-PCR, WB, Alizarin Red, and ALP staining. The effects of circ_0003865 on osteoporosis (OP) development was tested in murine osteoporosis model.Results: MEL promoted osteogenic differentiation of BMSCs. RNA sequencing revealed significant alterations in circRNA and mRNA profiles associated with multiple biological processes and signaling pathways. Circ_0003865 expression in BMSCs was significantly decreased by MEL treatment. Silencing of circ_0003865 promoted osteogenic differentiation of BMSCs. Overexpression of circ_0003865 abrogated the promotion of BMSCs osteogenic differentiation induced by MEL. Furthermore, circ_0003865 sponged miR-3653-3p to promote GAS1 expression in BMSCs. BMSC osteogenic differentiation was enhanced by miR-3653-3p overexpression. By contrast, miR-3653-3p silencing mitigated the promoted BMSC osteogenic differentiation caused by circ_0003865 silencing. Finally, circ_0003865 silencing repressed OP development in mouse model.Conclusion: MEL promotes BMSC osteogenic differentiation and inhibits osteoporosis pathogenesis by suppressing the expression of circ_0003865, which regulates GAS1 gene expression via sponging miR-3653-3p.

scholarly journals LncRNA LOC100506178 promotes osteogenic differentiation via regulating miR-214-5p-BMP2 axis in human bone marrow mesenchymal stem cells

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8909
Author(s):  
Lina Li ◽  
Jie Fang ◽  
Yi Liu ◽  
Li Xiao
Keyword(s):  
Bone Marrow ◽  
Osteogenic Differentiation ◽  
Human Bone ◽  
Human Bone Marrow ◽  
Bone Morphogenetic Protein 2 ◽  
Luciferase Reporter ◽  
Alizarin Red ◽  
Dental Implantation

Osteogenic differentiation is an important role in dental implantation. Long no coding RNAs (lncRNAs) are a novel class of noncoding RNAs that have significant effects in a variety of diseases. However, the function and mechanisms of LOC100506178 in osteogenic differentiation and migration of bone morphogenetic protein 2 (BMP2)-induced osteogenic differentiation of human bone marrow mesenchymalstem cells (hBMSCs) remain largely unclear. BMP2 was used to induce osteogenic differentiation of hBMSCs. Quantitative real time PCR (qRT-PCR) was used to examine the expression of LOC100506178, miR-214-5p, Runt-related transcription factor 2 (RUNX2), Osterix (Osx), and Alkaline Phosphatase (ALP) in BMP2-induced osteogenic differentiation of hBMSCs. The function of LOC100506178 and miR-214-5p was explored in vitro using Alizarin Red S Staining, ALP activity, as well as in vivo ectopic bone formation. Luciferase reporter assay was performed to assess the association between LOC100506178 and miR-214-5p, as well as miR-214-5p and BMP2. The miR-214-5p sponging potential of LOC100506178 was evaluated by RNA immunoprecipitation. In the present study, the expression of LOC100506178 was found to be increased in BMP2-induced osteogenic differentiation of hBMSCs, accompanied with decreased miR-214-5p expression and increased RUNX2, Osx and ALP expression. LOC100506178 significantly induced, while miR-214-5p suppressed the BMP2-induced osteogenic differentiation of hBMSCs. Mechanistically, LOC100506178 was directly bound to miR-214-5p and miR-214-5p targeted the 3′-untranslated region of BMP2 to negatively regulate its expression. In conclusion, our data indicate a novel molecular pathway LOC100506178/miR-214-5p/BMP2 in relation to hBMSCs differentiation into osteoblasts, which may facilitate bone anabolism.

scholarly journals Quercetin promotes bone marrow mesenchymal stem cell proliferation and osteogenic differentiation through the H19/miR-625-5p axis to activate the Wnt/β-catenin pathway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Bian ◽  
Shunqiang Xiao ◽  
Lei Yang ◽  
Jun Chen ◽  
Shifang Deng
Keyword(s):  
Bone Marrow ◽  
Osteogenic Differentiation ◽  
Protein Level ◽  
Cell Counting ◽  
Alizarin Red ◽  
Matrix Mineralization ◽  
Stem Cell Proliferation ◽  
Alp Activity ◽  
Marrow Mesenchymal Stem Cells ◽  
Quercetin Treatment

Abstract Background Quercetin and H19 can promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). However, whether quercetin regulates H19 expression to promote osteogenic differentiation of BMSCs is unclear. Methods BMSC proliferation, matrix mineralization, and alkaline phosphatase (ALP) activity were assessed using the Cell Counting Kit-8, ALP assay kit, and alizarin red staining kit, respectively. Expression of H19, miR-625-5p, BMP-2, osteocalcin, and RUNX2 were measured by qRT-PCR; β-catenin protein level was measured by western blotting. Results Quercetin promoted BMSC proliferation, enhanced ALP activity, and upregulated the expression of BMP-2, osteocalcin, and RUNX2 mRNAs, suggesting that it promoted osteogenic differentiation of BMSCs. Moreover, quercetin increased H19 expression, while the effect of quercetin on BMSCs was reversed by silencing H19 expression. Additionally, miR-625-5p, interacted with H19, was downregulated during quercetin-induced BMSC osteogenic differentiation, which negatively correlated with H19 expression. Silencing miR-625-5p expression promoted BMSC proliferation and osteogenic differentiation, whereas miR-625-5p overexpression weakened the effect of quercetin on BMSCs. Finally, quercetin treatment or downregulation of miR-625-5p expression increased β-catenin protein level in BMSCs. Upregulation or downregulation of miR-625-5p or H19 expression, respectively, inhibited β-catenin protein level in quercetin treated-BMSCs. Conclusion H19 promotes, while miR-625-5p inhibits BMSC osteogenic differentiation. Quercetin activates the Wnt/β-catenin pathway and promotes BMSC osteogenic differentiation via the H19/miR-625-5p axis.

scholarly journals Adrenomedullin 2 improves bone regeneration in type 1 diabetic rats by restoring imbalanced macrophage polarization and impaired osteogenesis

2020 ◽  
Author(s):  
Feng Wang ◽  
Lingchi Kong ◽  
Wenbo Wang ◽  
Li Shi ◽  
Mengwei Wang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Regeneration ◽  
Macrophage Polarization ◽  
Osteogenic Potential ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diabetic Patients ◽  
M2 Macrophage ◽  
Alizarin Red ◽  
M1 Macrophage

Abstract Background Both advanced glycation end products (AGEs) and AGE-mediated M1 macrophage polarization contribute to bone marrow mesenchymal stem cell (BMSC) dysfunction, leading to impaired bone regeneration in type 1 diabetes mellitus (T1DM). Adrenomedullin 2 (ADM2), an endogenous bioactive peptide belonging to the calcitonin gene-related peptide family, exhibits various biological activities associated with the inhibition of inflammation and reduction of insulin resistance. However, the effects and underlying mechanisms of ADM2 in AGE-induced macrophage M1 polarization, BMSC dysfunction, and impaired bone regeneration remain poorly understood. Methods The polarization of bone marrow-derived macrophages was verified by flow cytometry analysis. In addition, alkaline phosphatase (ALP) staining, ALP activity detection, and alizarin red staining were performed to assess the osteogenesis of BMSCs. Quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence staining were used to assess polarization markers, PPARγ/IκBα/NF-κB signaling, and osteogenic markers. In vivo, a distraction osteogenesis (DO) rat model with T1DM was established, and the tibia samples were collected at different time points for radiological, biomechanical, and histological analyses, to verify the effects of ADM2 in terms of bone regeneration and M2 polarization under diabetic conditions. Results ADM2 treatment reversed the M1 macrophage polarization induced by AGEs towards the M2 phenotype, which was partially achieved by the PPARγ-mediated inhibition of NF-κB signaling. The PPARγ inhibitor GW9662 significantly attenuated the effects of ADM2. Besides, ADM2 treatment improved the AGE-impaired osteogenic potential of BMSCs in vitro. Furthermore, ADM2 accelerated bone regeneration, as revealed by improved radiological and histological manifestations and biomechanical parameters, accompanied by improved M2 macrophage polarization in diabetic DO rats, and these effects were partially blocked by GW9662 administration. Conclusions These results indicate that ADM2 enhances diabetic bone regeneration during DO, by attenuating AGE-induced imbalance in macrophage polarization, partly through PPARγ/IκBα/NF-κB signaling, and improving AGE-impaired osteogenic differentiation of BMSCs simultaneously. These findings reveal that ADM2 may serve as a potential bioactive factor for promoting bone regeneration under diabetic conditions, and imply that management of inflammation and osteogenesis, in parallel, might be a promising therapeutic strategy for diabetic patients during DO treatment.

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