Melatonin rescues the mitochondrial function of bone marrow-derived mesenchymal stem cells and improves the repair of osteoporotic bone defect in ovariectomized rats

Osteoporotic bone defects, a severe complication of osteoporosis, are distinguished by a delayed bone healing process and poor repair quality. While bone marrow-derived mesenchymal stem cells (BMMSCs) are the primary origin of bone-forming osteoblasts, their mitochondrial function is impaired, leading to inadequate bone regeneration in osteoporotic patients. Melatonin is well-known for its antioxidant properties and regulation on bone metabolism. The present study postulated that melatonin has the potential to enhance the repair of osteoporotic bone defects by restoring the mitochondrial function of BMMSCs. In vitro administration of melatonin at varying concentrations (0.01, 1, and 100 μM) demonstrated a significant dose-dependent improvement in the mitochondrial function of BMMSCs obtained from ovariectomized rats (OVX-BMMSCs), as indicated by an elevation in mitochondrial membrane potential, adenosine triphosphate synthesis and expression of mitochondrial respiratory chain factors. Melatonin reduced the level of mitochondrial superoxide by activating the silent information regulator type 1 (SIRT1) and its downstream antioxidant enzymes, particularly superoxide dismutase 2 (SOD2). The protective effects of melatonin were found to be nullified upon silencing of Sirt1 or Sod2, underscoring the crucial role of the SIRT1-SOD2 axis in the melatonin-induced enhancement of mitochondrial energy metabolism in OVX-BMMSCs. To achieve a sustained and localized release of melatonin, silk fibroin scaffolds loaded with melatonin (SF@MT) were fabricated. The study involved the surgical creation of bilateral femur defects in OVX rats, followed by the implantation of SF@MT scaffolds. The results indicated that the application of melatonin partially restored the mitochondrial energy metabolism and osteogenic differentiation of OVX-BMMSCs by reinstating mitochondrial redox homeostasis. These findings suggest that the localized administration of melatonin through bone implants holds potential as a therapeutic approach for addressing osteoporotic bone defects.

ATP-induced cell death: a novel hypothesis for osteoporosis

ATP-induced cell death has emerged as a captivating realm of inquiry with profound ramifications in the context of osteoporosis. This study unveils a paradigm-shifting hypothesis that illuminates the prospective involvement of ATP-induced cellular demise in the etiology of osteoporosis. Initially, we explicate the morphological attributes of ATP-induced cell death and delve into the intricacies of the molecular machinery and regulatory networks governing ATP homeostasis and ATP-induced cell death. Subsequently, our focus pivots towards the multifaceted interplay between ATP-induced cellular demise and pivotal cellular protagonists, such as bone marrow-derived mesenchymal stem cells, osteoblasts, and osteoclasts, accentuating their potential contributions to secondary osteoporosis phenotypes, encompassing diabetic osteoporosis, glucocorticoid-induced osteoporosis, and postmenopausal osteoporosis. Furthermore, we probe the captivating interplay between ATP-induced cellular demise and alternative modalities of cellular demise, encompassing apoptosis, autophagy, and necroptosis. Through an all-encompassing inquiry into the intricate nexus connecting ATP-induced cellular demise and osteoporosis, our primary goal is to deepen our comprehension of the underlying mechanisms propelling this malady and establish a theoretical bedrock to underpin the development of pioneering therapeutic strategies.

BM-MSCs alleviate diabetic nephropathy in male rats by regulating ER stress, oxidative stress, inflammation, and apoptotic pathways

Introduction: Diabetic nephropathy (DN), a chronic kidney disease, is a major cause of end-stage kidney disease worldwide. Mesenchymal stem cells (MSCs) have become a promising option to mitigate several diabetic complications. Methods: In this study, we evaluated the therapeutic potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) in a rat model of STZ-induced DN. After the confirmation of diabetes, rats were treated with BM-MSCs and sacrificed at week 12 after treatment. Results: Our results showed that STZ-induced DN rats had extensive histopathological changes, significant upregulation in mRNA expression of renal apoptotic markers, ER stress markers, inflammatory markers, fibronectin, and intermediate filament proteins, and reduction of positive immunostaining of PCNA and elevated P53 in kidney tissue compared to the control group. BM-MSC therapy significantly improved renal histopathological changes, reduced renal apoptosis, ER stress, inflammation, and intermediate filament proteins, as well as increased positive immunostaining of PCNA and reduced P53 in renal tissue compared to the STZ-induced DN group. Conclusion: In conclusion, our study indicates that BM-MSCs may have therapeutic potential for the treatment of DN and provide important insights into their potential use as a novel therapeutic approach for DN.

The ameliorating effects of mesenchymal stem cells compared to α-tocopherol on apoptosis and autophagy in streptozotocin-induced diabetic rats: Implication of PI3K/Akt signaling pathway and entero-insular axis

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are considered a novel regenerative therapy that holds much potential. This study aimed to examine and compare the ameliorative effects of BM-MSCs compared to α-tocopherol (α-Toc) on apoptosis, autophagy, and β-cell function in a rat model of streptozotocin (STZ)-induced diabetes and further analyzed the implications and interrelations of the entero-insular axis, and type I phosphoinositide 3-kinase (PI3K)/Akt signaling. Forty adult male albino rats were categorized into four groups (n = 10, in each): control group, STZ-induced diabetic group (single i.p. injection of STZ 45 mg/kg), diabetic and treated with BM-MSCs injection, diabetic and treatment with α-Toc p.o. The serum glucose, insulin, nitric oxide (NO), and catalase (CAT) were measured. Histopathological examination of the pancreas, the expression levels of insulin, CD44, caspase-3, autophagy markers, P13K/Akt, and pancreas/duodenum homeobox protein 1, in pancreatic tissue, and glucose-dependent insulinotropic polypeptide (GIP) in the duodenum were detected by hematoxylin and eosin staining, immunofluorescence labeling, and by quantitative real-time polymerase chain reaction. The diabetic rats showed reduced insulin, hyperglycemia, nitrosative stress (NO, CAT), augmented apoptosis (caspase 3), impaired autophagy (p62/SQSTM1, LC3), downregulated PI3K/Akt pathway and increased GIP expression, and degeneration of pancreatic islets. Treatment with either BM-MSCs or α-Toc suppressed the nitrosative stress, reduced apoptosis, recovered autophagy, upregulated PI3K/Akt pathway, and subsequently increased insulin levels, decreased blood glucose, and downregulated GIP expression with partial restoration of pancreatic islets. Based on our findings, the cytoprotective effects of BM-MSCs and α-Toc in type 1-induced diabetes appeared to be related to repaired autophagy and recovered PI3K/Akt signaling. Moreover, we reported their novel effects on reversing intestinal GIP expression level. The effect of BM-MSCs was notably superior to that of α-Toc.

Efficiency of Bone Marrow-Derived Mesenchymal Stem Cells and Hesperetin in the Treatment of Streptozotocin-Induced Type 1 Diabetes in Wistar Rats

Type 1 diabetes mellitus (T1DM) was established to be ameliorated by islet transplantation, but the shortage of the transplanted human islet tissue and the use of immunosuppressive drugs to inhibit the rejection of allogeneic grafts make this type of therapy is limited. Nowadays, therapy with stem cells is one of the most promising future treatments. This kind of therapy could have a profound impact on both replacement, as well as regenerative therapies, to improve or even cure various disorders, including diabetes mellitus. Flavonoids have also been shown to possess anti-diabetic effects. Thus, this study aims to evaluate the effectiveness of the bone marrow-derived mesenchymal stem cells (BM-MSCs) and hesperetin in the treatment of a T1DM rat model. T1DM was induced in male Wistar rats that had been starved for 16 h via intraperitoneal injection of STZ at a dose of 40 mg/kg body weight (b.wt.). After 10 days of STZ injection, the diabetic rats were allocated into four groups. The first diabetic animal group was considered a diabetic control, while the other three diabetic animal groups were treated for six weeks, respectively, with hesperetin (given orally at a dose of 20 mg/kg b.wt.), BM-MSCs (injected intravenously at a dose of 1 × 10⁶ cells/rat/week), and their combination (hesperetin and BM-MSCs). The use of hesperetin and BM-MSCs in the treatment of STZ-induced diabetic animals significantly improved the glycemic state, serum fructosamine, insulin and C-peptide levels, liver glycogen content, glycogen phosphorylase, glucose-6-phosphatase activities, hepatic oxidative stress, and mRNA expressions of NF-κB, IL-1β, IL-10, P53, and Bcl-2 in pancreatic tissue. The study suggested the therapy with both hesperetin and BM-MSCs produced marked antihyperglycemic effects, which may be mediated via their potencies to ameliorate pancreatic islet architecture and insulin secretory response, as well as to decrease hepatic glucose output in diabetic animals. The improvement effects of hesperetin and BM-MSCs on the pancreatic islets of diabetic rats may be mediated via their antioxidant, anti-inflammatory, and antiapoptotic actions.

Hypoxic preconditioned mesenchymal stem cells ameliorate rat brain injury after cardiopulmonary resuscitation by suppressing neuronal pyroptosis

Cardiac arrest (CA) can result in cerebral ischaemia-reperfusion injury and poor neurological outcomes. While bone marrow-derived mesenchymal stem cells (BMSCs) have been shown to have protective effects in brain ischaemic disease, their efficacy can be reduced by the poor oxygen environment. In this study, we investigated the neuroprotective effects of hypoxic preconditioned BMSCs (HP-BMSCs) and normoxic BMSCs C (N-BMSCs) in a cardiac arrest rat model by examining their ability to ameliorate cell pyroptosis. The mechanism underlying the process was also explored. Cardiac arrest was induced in rats for 8 min and surviving rats received 1 × 10⁶ normoxic/hypoxic BMSCs or PBS via intracerebroventricular (ICV) transplantation. Neurological function of rats was evaluated using neurological deficit scores (NDSs) and examined for brain pathology. Serum S100B and neuron-specific enolase (NSE) levels and cortical proinflammatory cytokines were measured to evaluate brain injury. Pyroptosis-related proteins in the cortex after cardiopulmonary resuscitation (CPR) were measured using western blotting and immunofluorescent staining. Transplanted BMSCs were tracked using bioluminescence imaging. Results showed significantly better neurological function and neuropathological damage after transplantation with HP-BMSCs. In addition, HP-BMSCs reduced levels of pyroptosis-related proteins in the rat cortex after CPR and significantly reduced levels of biomarkers for brain injury. Mechanistically, HP-BMSCs alleviated brain injury by reducing the expressions of HMGB1, TLR4, NF-κB p65, p38 MAPK and JNK in the cortex. Our study demonstrated that hypoxic preconditioning could enhance the efficacy of BMSCs in alleviating post-resuscitation cortical pyroptosis. This effect may be related to the regulation of the HMGB1/TLR4/NF-κB, MAPK signalling pathways.

Bone Marrow-Derived Mesenchymal Stem Cell Implants for the Treatment of Focal Chondral Defects of the Knee in Animal Models: A Systematic Review and Meta-Analysis

Osteoarthritis remains an unfortunate long-term consequence of focal cartilage defects of the knee. Associated with functional loss and pain, it has necessitated the exploration of new therapies to regenerate cartilage before significant deterioration and subsequent joint replacement take place. Recent studies have investigated a multitude of mesenchymal stem cell (MSC) sources and polymer scaffold compositions. It is uncertain how different combinations affect the extent of integration of native and implant cartilage and the quality of new cartilage formed. Implants seeded with bone marrow-derived MSCs (BMSCs) have demonstrated promising results in restoring these defects, largely through in vitro and animal studies. A PRISMA systematic review and meta-analysis was conducted using five databases (PubMed, MEDLINE, EMBASE, Web of Science, and CINAHL) to identify studies using BMSC-seeded implants in animal models of focal cartilage defects of the knee. Quantitative results from the histological assessment of integration quality were extracted. Repair cartilage morphology and staining characteristics were also recorded. Meta-analysis demonstrated that high-quality integration was achieved, exceeding that of cell-free comparators and control groups. This was associated with repair tissue morphology and staining properties which resembled those of native cartilage. Subgroup analysis showed better integration outcomes for studies using poly-glycolic acid-based scaffolds. In conclusion, BMSC-seeded implants represent promising strategies for the advancement of focal cartilage defect repair. While a greater number of studies treating human patients is necessary to realize the full clinical potential of BMSC therapy, high-quality integration scores suggest that these implants could generate repair cartilage of substantial longevity.

Bone marrow-derived mesenchymal stem cells expressing BMP2 suppress glioma stem cell growth and stemness through Bcl-2/Bax signaling

Objectives

To find an effective molecule that controls glioma stem cell (GSC) proliferation and differentiation for the development of future therapeutic interventions against glioblastoma.

Material and Methods

Bone marrow-derived mesenchymal stem cells (BMSCs) were infected with a lentiviral vector to express BMP2. Cell viability, cell counting, and tumor sphere formation assays, as well as flow cytometry, immunofluorescence staining, and Western blotting were used to investigate the effects of BMSC-BMP2 on GSCs.

Results

The results of flow cytometry and the CKK-8 assay showed that BMSC-BMP2 induced GSC apoptosis while inhibiting proliferation. BMSC-BMP2 decreased GSC neurosphere formation and neurospheres' transverse and vertical diameter. Meanwhile, BMSC-BMP2 downregulated GSC Nanog and OCT4 expression levels, suggesting stemness inhibition. Western blotting showed that BMSC-BMP2 increased Bax protein expression and significantly decreased Bcl-2 protein expression. Accordingly, the Bcl-2/Bax ratio increased.

Conclusion

BMSC-BMP2 could effectively inhibit GSC proliferation, induce GSC apoptosis, and decrease GSC stemness, thereby providing a novel strategy for treating malignant glioma.

Extracellular vesicles produced by bone marrow mesenchymal stem cells overexpressing programmed death-ligand 1 ameliorate dextran sodium sulfate-induced ulcerative colitis in rats by regulating Th17/Treg cell balance through PTEN/PI3K/AKT/mTOR axis

BACKGROUND AND AIM

Programmed death-ligand 1 (PD-L1) was involved in regulating Th17/Treg cell balance in ulcerative colitis (UC). Extracellular vesicles (EVs) from genetically modified bone marrow mesenchymal stem cells (BMSCs) can serve as a stable delivery system to overexpress PD-L1. The study was designed to evaluate the therapeutic mechanism of BMSC-EVs overexpressing PD-L1 (PD-L1-EVs) on ulcerative colitis.

METHODS

Experimental model of UC was established in rats by drinking 5% dextran sulfate sodium (DSS). Apoptosis-related proteins, inflammatory response-related factors and oxidative stress related mediators were detected. Westernblot was used to detecte key proteins in the PI3K/AKT signaling pathway and its downstream effectors. The CD4⁺ Foxp3⁺ Treg cells and CD4⁺ IL-17A⁺ Th17 cells in spleen and mesenteric lymph nodes (MLNs) was detected by flow cytometry.

RESULTS

PD-L1-EVs significantly alleviated the manifestations and pathological damage of UC rats by inhibiting the expression of IFN-γ, IL-1β, IL-8, IL-6, IL-2, BAX, NF-κB, TNF-α, MPO, and MDA, and up-regulating the expression of IL-4, BCL-2, SOD, and GSH. Furthermore, the proportions of Th17 cells were decreased and that of Treg cells were upregulated by PD-L1-EVs treatment. PTEN inhibitors (bpv) partially abolished the inhibitory effect of PD-L1-EVs on PI3K-AKT signaling and impaired the therapeutic efficacy of PD-L1-EVs.

CONCLUSIONS

PD-L1-EVs mitigated colonal inflammation, apoptosis and oxidative stress through blocking the activation of PI3K/Akt/mTOR pathway and regulating the balance of Th17/Treg cells.

Preconditioning with Trehalose Protects the Bone Marrow-Derived Mesenchymal Stem Cells Under Oxidative Stress and Enhances the Stem Cell-Based Therapy for Cerebral Ischemic Stroke

Bone marrow-derived mesenchymal stem cell (BMSC) transplantation has emerged as a potential treatment for ischemic stroke. Preconditioning with pharmacological agents before cell transplantation has been shown to increase the efficiency of cell therapy. In this study, trehalose (Tre), an autophagy inducer, was used as a pharmacological agent to treat BMSCs, and the neuroprotective effect of BMSCs preconditioned with Tre on cerebral ischemia was assessed. BMSCs were treated in vitro with different concentrations of Tre. Immunofluorescence staining of LC3B was performed to detect autophagy, and Western blotting for LC3, Beclin1, p-AMPK, and p-mTOR was performed. Flow cytometry and Western blotting analysis were performed to measure cell apoptosis in the presence of hydrogen peroxide (H₂O₂). Enzyme-linked immunosorbent assay was used to test the secretion levels of neurotrophic factors. An in vivo ischemia/reperfusion model was generated by middle cerebral artery occlusion in male Sprague Dawley rats, and Tre-preconditioned BMSCs were administered intralesionally 24 hours after ischemic injury. Histopathological examination and neurological function studies were conducted. In vitro, Tre promotes autophagy of BMSCs through the activation of the AMPK signal pathway. Tre protected BMSCs from H₂O₂-induced cell viability reduction and apoptosis. Moreover, Tre pretreatment increased the secretion of brain-derived neurotrophic factor, vascular endothelial growth factor, and hepatocyte growth factor. In vivo, preconditioning with Tre could further enhance the survival of BMSCs, reduce infarct size, alleviate cell apoptosis, abate vessel decrease, and ultimately improve functional recovery. Our study indicates that Tre can enhance the survival of BMSCs under oxidative stress and enhance BMSC-based treatment of ischemia/reperfusion injury.

The impact of bone marrow-derived mesenchymal stem cells on experimental testiculartorsion in rats

BACKGROUND

The aim of this study was to investigate the healing effects of bone marrow-derived mesenchymal stem cells (BMMSCs) on experimental testicular torsion in rats.

METHODS

Three groups consisting of 10 Wistar albino rats were created. In Group I, the left testicle was explored and relocated in the scrotum without any attempt to modify it. In Group II, the left testicle underwent torsion for three h and then was detorsed and relocated. In Group III, in addition to torsion and detorsion, BM-MSCs were administered intratesticularly. The rats were sacrificed on the seventh day, and the healing status of the testicles was investigated with histopathological and biochemical analyses. BM-MSC involvement was investigated by immunofluorescence microscopy. Statistical analysis was performed using SPSS 15.0. A p-value < 0.05 was considered statistically significant for all variables.

RESULTS

Immunofluorescence microscopy showed that BM-MSCs were located around the Leydig cells in Group III. Under light microscopy, the mean Johnsen Score of Group III was significantly higher than that of Group II (p = 0.035). The interleukin-10 (IL-10) level was significantly higher in Group III compared to Group II (p = 0.003). While the malondialdehyde (MDA) values in Group I (the control group) were lower than in the other groups (p = 0.037), the superoxide dismutase (SOD) values were similar (p = 0.158). Although there was no statistically significant difference between Group II and Group III in terms of MDA, it was lower in Group III. Although the tissue SOD levels were higher in Group III than in Group II, the difference was not statistically significant.

DISCUSSION

: This study has demonstrated that BM-MSCs significantly corrected the Johnsen Score and increased anti-inflammatory cytokine levels after testicular torsion. BM-MSCs can be used in testicular torsion as supportive therapy to minimize tissue damage.

Macrophages and Bone Marrow-Derived Mesenchymal Stem Cells Work in Concert to Promote Fracture Healing: A Brief Review

Bone marrow-derived mesenchymal stem cell (BMSC)-based and macrophage-based cell therapy are regarded as promising strategies to promote fracture healing because of incredible osteogenic potential of BMSCs and typical immunomodulatory function of macrophages. Apart from their respective key roles, accumulative evidence has also demonstrated the importance of cross talk between these two cell types in fracture healing process. This review takes a deep insight into the recent research progress of the synergic performance of BMSCs and macrophages by discussing not only the cells own functions but also the relevant impact factors and mechanisms (ambient microenvironment stimulus, miRNAs, etc). The aim of this review is to provide some valuable cues and technique support for the macrophage- and BMSC-related research, which will be helpful to propel BMSC/macrophage-based combined cell therapy for bone fracture treatment.

ac4C acetylation of RUNX2 catalyzed by NAT10 spurs osteogenesis of BMSCs and prevents ovariectomy-induced bone loss

N-acetyltransferase 10 (NAT10) is the key enzyme for N4-acetylcytidine (ac4C) modification of mRNA, which participates in various cellular processes and is related to many diseases. Here, we explore the relationships among osteoblast differentiation, NAT10, and ac4C, and we found that NAT0 expression and the ac4C level of total RNA were decreased in the bone tissues of bilateral ovariectomized (OVX) mice and osteoporosis patients. Adenoviruses overexpressing NAT10 reversed bone loss, and Remodelin, an NAT10 inhibitor, enhanced the loss of bone mass in OVX mice. Moreover, bone marrow-derived mesenchymal stem cells (BMSCs) with low-level ac4C modification formed fewer calcium nodules in vitro with NAT10 silencing, whereas BMSCs with high-level ac4C modification formed more calcium nodules with NAT10 overexpression. Moreover, we demonstrated that the ac4C level of runt-related transcription factor 2 (RUNX2) mRNA was increased after BMSCs were cultured in osteogenic medium (OM) and decreased after NAT10 silencing. The RUNX2 mRNA half-life and protein expression decreased after silencing NAT10 in BMSCs. Therefore, NAT10-based ac4C modification promotes the osteogenic differentiation of BMSCs by regulating the RUNX2 ac4C level. Because abnormal levels of NAT10 are probably one of the mechanisms responsible for osteoporosis, NAT10 is a new potential therapeutic target for this disease.

The impact of bone marrow-derived mesenchymal stem cells on experimental testicular torsion in rats

BACKGROUND/AIM

The aim of this study was to investigate the healing effects of bone marrow-derived mesenchymal stem cells (BM-MSCs) on experimental testicular torsion in rats.

MATERIALS AND METHODS

Three groups consisting of 10 Wistar albino rats each were created. In Group I, the left testicle was explored and relocated in the scrotum without any attempt to modify it. In Group II, the left testicle underwent torsion for three hours and then was detorsed and relocated. In Group III, in addition to torsion and detorsion, BM-MSCs were administered intratesticularly. The rats were sacrificed on the seventh day, and the healing status of the testicles was investigated with histopathological and biochemical analyses. BM-MSC involvement was investigated by immunofluorescence microscopy. Statistical analysis was performed using SPSS 15.0. A p-value < 0.05 was considered statistically significant for all variables.

RESULTS

Immunofluorescence microscopy showed that BM-MSCs were located around the Leydig cells in Group III. Under light microscopy, the mean Johnsen Score of Group III was significantly higher than that of Group II (p = 0.035). The interleukin-10 (IL-10) level was significantly higher in Group III compared to Group II (p = 0.003). While the malondialdehyde (MDA) values in Group I (the control group) were lower than in the other groups (p = 0.037), the superoxide dismutase (SOD) values were similar (p = 0.158). Although there was no statistically significant difference between Group II and Group III in terms of MDA, it was lower in Group III. Although the tissue SOD levels were higher in Group III than in Group II, the difference was not statistically significant.

PKD1 alleviates oxidative stress-inhibited osteogenesis of rat bone marrow-derived mesenchymal stem cells through TAZ activation

Oxidative stress is known to inhibit osteogenesis and PKD1 is implicated in bone remodeling and skeletogenesis. In the present study, we explored the role of PKD1 in osteogenesis under oxidative stress. H2 O2 was used to induce oxidative stress in rat bone marrow (BM)-mesenchymal stem cells (MSCs) during osteoblast differentiation. Alkaline phosphatase (ALP) activity, calcium deposits, and the RUNX2 marker were assayed to determine osteogenic differentiation. The correlation of PKD1, Sirt1, c-MYC, and TAZ was further confirmed by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay. We found that H2 O2 induced the downregulation of PKD1 expression and the upregulation of c-MYC, and Sirt1 was accompanied by decreasing cell viability in BM-MSCs. During osteogenic differentiation, the expression of PKD1 was upregulated significantly whereas Sirt1 tended to be upregulated mildly under normal conditions. Both PKD1 and Sirt1 were upregulated upon oxidative stress. The positive correlation of PKD1 expression with osteogenic differentiation under normal conditions might be hindered by oxidative stress and PKD1 could interact with TAZ under oxidative stress to regulate osteogenic differentiation. Our results suggest that PKD1 may alleviate oxidative stress-inhibited osteogenesis of rat BM-MSCs through TAZ activation.

Intrinsic osteoinductivity of PCL-DA/PLLA semi-IPN shape memory polymer scaffolds

Engineering osteoinductive, self-fitting scaffolds offers a potential treatment modality to repair irregularly shaped craniomaxillofacial bone defects. Recently, we innovated on osteoinductive poly(ε-caprolactone)-diacrylate (PCL-DA) shape memory polymers (SMPs) to incorporate poly-L-lactic acid (PLLA) into the PCL-DA network, forming a semi-interpenetrating network (semi-IPN). Scaffolds formed from these PCL-DA/PLLA semi-IPNs display stiffnesses within the range of trabecular bone and accelerated degradation relative to scaffolds formed from slowly degrading PCL-DA SMPs. Herein, we demonstrate for the first time that PCL-DA/PLLA semi-IPN SMP scaffolds show increased intrinsic osteoinductivity relative to PCL-DA. We also confirm that application of a bioinspired polydopamine (PD) coating further improves the osteoinductive capacity of these PCL-DA/PLLA semi-IPN SMPs. In the absence of osteogenic supplements, protein level assessment of human mesenchymal stem cells (h-MSCs) cultured in PCL-DA/PLLA scaffolds revealed an increase in expression of osteogenic markers osterix, bone morphogenetic protein-4 (BMP-4), and collagen 1 alpha 1 (COL1A1), relative to PCL-DA scaffolds and osteogenic medium controls. Likewise, the expression of runt-related transcription factor 2 (RUNX2) and BMP-4 was elevated in the presence of PD-coating. In contrast, the chondrogenic and adipogenic responses associated with the scaffolds matched or were reduced relative to osteogenic medium controls, indicating that the scaffolds display intrinsic osteoinductivity.

Functional Mechanism of Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Animal Models with Alzheimer's Disease: Inhibition of Neuroinflammation

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer’s disease. However, the underlying mechanisms remain to be determined. Available data demonstrate transplanted BMMSCs can inhibit neuroinflammation, which may be related to microglial M1/M2 polarization and is regulated by the secretion of autocrine and paracrine cytokines. BMMSCs also mitigate Aβ plaques and Tau tangles in the brain, which may be associated with the recruitment of peripheral blood monocytes and the subsequent comprehensive effects. The therapeutic effects of stem cells involve potential mechanisms such as immunomodulation, apoptosis, and proliferation. BMMSC-mediated functional reconstruction through dynamic remodeling develops a novel balance. Herein, present review recapitulates the molecular basis of BMMSC-assisted biological processes and summarizes the possible mechanisms related to the interaction between BMMSCs and microglia. The transplanted BMMSCs can suppress neuroinflammation that plays a key role in the pathogenesis of Alzheimer’s disease.

Mesenchymal Stem Cell-Induced Anti-Neuroinflammation Against Traumatic Brain Injury

Traumatic brain injury (TBI) is a pervasive and damaging form of acquired brain injury (ABI). Acute, subacute, and chronic cell death processes, as a result of TBI, contribute to the disease progression and exacerbate outcomes. Extended neuroinflammation can worsen secondary degradation of brain function and structure. Mesenchymal stem cell transplantation has surfaced as a viable approach as a TBI therapeutic due to its immunomodulatory and regenerative features. This article examines the role of inflammation and cell death in ABI as well as the effectiveness of bone marrow-derived mesenchymal stem/stromal cell (BM-MSC) transplants as a treatment for TBI. Furthermore, we analyze new studies featuring transplanted BM-MSCs as a neurorestorative and anti-inflammatory therapy for TBI patients. Although clinical trials support BM-MSC transplants as a viable TBI treatment due to their promising regenerative characteristics, further investigation is imperative to uncover innovative brain repair pathways associated with cell-based therapy as stand-alone or as combination treatments.

Combination of Stem Cells and Rehabilitation Therapies for Ischemic Stroke

Stem cell transplantation with rehabilitation therapy presents an effective stroke treatment. Here, we discuss current breakthroughs in stem cell research along with rehabilitation strategies that may have a synergistic outcome when combined together after stroke. Indeed, stem cell transplantation offers a promising new approach and may add to current rehabilitation therapies. By reviewing the pathophysiology of stroke and the mechanisms by which stem cells and rehabilitation attenuate this inflammatory process, we hypothesize that a combined therapy will provide better functional outcomes for patients. Using current preclinical data, we explore the prominent types of stem cells, the existing theories for stem cell repair, rehabilitation treatments inside the brain, rehabilitation modalities outside the brain, and evidence pertaining to the benefits of combined therapy. In this review article, we assess the advantages and disadvantages of using stem cell transplantation with rehabilitation to mitigate the devastating effects of stroke.

Andrographolide Reduces Lipid Droplet Accumulation in Adipocytes Derived from Human Bone Marrow Mesenchymal Stem Cells by Suppressing Regulators of Adipogenesis

Obesity has become a major public health concern; so, a strategy to prevent or reduce obesity is a priority. The inhibition of lipid droplet accumulation and adipogenesis process provides a target for the treatment of obesity. Herein, the effect of andrographolide (AP) on lipid accumulation in adipocytes derived from human bone marrow mesenchymal stem cells (hBM-MSCs) was examined. AP at concentrations of 1, 2.5, 5, and 10 μM reduced lipid droplet accumulation in the adipocytes by suppressing the adipogenic differentiation of hBM-MSCs. Concurrently, the expressions of adipogenic marker genes and the level of adipokines secreted by adipocytes were suppressed. Gene screening analysis showed a negative regulation of genes involved in the adipogenesis process. In conclusion, we demonstrated for the first time an antilipid accumulation in adipocytes from hBM-MSCs by AP. The compound may potentially be a novel therapeutic agent for the treatment of obesity as well as obesity-related diseases.

Effect of Different Bone Grafting Materials and Mesenchymal Stem Cells on Bone Regeneration: A Micro-Computed Tomography and Histomorphometric Study in a Rabbit Calvarial Defect Model

This study evaluated the new bone formation potential of micro-macro biphasic calcium phosphate (MBCP) and Bio-Oss grafting materials with and without dental pulp-derived mesenchymal stem cells (DPSCs) and bone marrow-derived mesenchymal stem cells (BMSCs) in a rabbit calvarial bone defect model. The surface structure of the grafting materials was evaluated using a scanning electron microscope (SEM). The multipotent differentiation characteristics of the DPSCs and BMSCs were assessed. Four circular bone defects were created in the calvarium of 24 rabbits and randomly allocated to eight experimental groups: empty control, MBCP, MBCP+DPSCs, MBCP+BMSCs, Bio-Oss+DPSCs, Bio-Oss+BMSCs, and autogenous bone. A three-dimensional analysis of the new bone formation was performed using micro-computed tomography (micro-CT) and a histological study after 2, 4, and 8 weeks of healing. Homogenously porous structures were observed in both grafting materials. The BMSCs revealed higher osteogenic differentiation capacities, whereas the DPSCs exhibited higher colony-forming units. The micro-CT and histological analysis findings for the new bone formation were consistent. In general, the empty control showed the lowest bone regeneration capacity throughout the experimental period. By contrast, the percentage of new bone formation was the highest in the autogenous bone group after 2 (39.4% ± 4.7%) and 4 weeks (49.7% ± 1.5%) of healing (p < 0.05). MBCP and Bio-Oss could provide osteoconductive support and prevent the collapse of the defect space for new bone formation. In addition, more osteoblastic cells lining the surface of the newly formed bone and bone grafting materials were observed after incorporating the DPSCs and BMSCs. After 8 weeks of healing, the autogenous bone group (54.9% ± 6.1%) showed a higher percentage of new bone formation than the empty control (35.3% ± 0.5%), MBCP (38.3% ± 6.0%), MBCP+DPSC (39.8% ± 5.7%), Bio-Oss (41.3% ± 3.5%), and Bio-Oss+DPSC (42.1% ± 2.7%) groups. Nevertheless, the percentage of new bone formation did not significantly differ between the MBCP+BMSC (47.2% ± 8.3%) and Bio-Oss+BMSC (51.2% ± 9.9%) groups and the autogenous bone group. Our study results demonstrated that autogenous bone is the gold standard. Both the DPSCs and BMSCs enhanced the osteoconductive capacities of MBCP and Bio-Oss. In addition, the efficiency of the BMSCs combined with MBCP and Bio-Oss was comparable to that of the autogenous bone after 8 weeks of healing. These findings provide effective strategies for the improvement of biomaterials and MSC-based bone tissue regeneration.

Circular RNA circ_0000020 promotes osteogenic differentiation to reduce osteoporosis via sponging microRNA miR-142-5p to up-regulate Bone Morphogenetic Protein BMP2

This study was designed to study functions of Circ_0000020 during osteogenic differentiation. First, we used RT-qPCR to detect the expression of Circ_0000020, miR-142-5p and osteogenesis-related genes, whereas western blot analysis detected the expression of osteogenesis markers after the osteogenic differentiation of primary BMSCs isolated from rats. Alkaline phosphatase (ALP) activity and alizarin red Sstaining validated osteoblast phenotypes. Flow cytometry was used to detect cell apoptosis. Sh-Circ_0000020 was used to study the function of Circ_0000020 in osteogenic differentiation of BMSCs. Luciferase assay and RNA immunoprecipitation were used to validate the interaction between Circ_0000020 and miR-142-5p, and BMP2 and miR-142-5p. Co-transfection of miR-142-5p and sh-Circ_0000020 was used to verify the downstream signaling pathway. Circ_0000020 expression was up-regulated during osteogenic differentiation, whereas miR-142-5p expression was significantly decreased. Silencing Circ_0000020 inhibited osteogenic differentiation and promoted apoptosis, and inhibited ALP activity and mineralization ability. Moreover, Circ_0000020 interacts directly with miR-142-5p which binds to the BMP2 3ʹUTR and inhibits its expression. Additionally, co-transfection of miR-142-5p inhibitors and sh-Circ_0000020 rescued down-regulated BMP2, increased the expression osteogenesis-related gene expressions, and thereby rescued the inhibition of osteogenic differentiation induced by Circ_0000020 silencing. Furthermore, co-transfection of miR-142-5p inhibitors and sh-Circ_0000020 reversed Circ_0000020 silencing-induced downregulation of p-Smad1/5/8, Runx2, and Osterix protein levels. Circ_0000020 regulates BMP2 expression through sponging miR-142-5p as ceRNA, thereby positively regulating BMSCs osteogenic differentiation through Circ_0000020/miR-142-5p/BMP2/SMAD-dependent signaling pathway.

Three-Dimensional Cell Printed Lock-Key Structure for Oral Soft and Hard Tissue Regeneration

Alveolar ridge absorbs rapidly following tooth extraction. To promote implant rehabilitation, an adequate bone and soft tissue volume are required. Three-dimensional (3D) cell printing technique provides the advantages of precise spatial distribution and personalization. In this study, 3D cell printing was used to establish a soft-hard construct that is composed of alginate/gelatin (AG)/gingival fibroblast cells (GFs) and alginate/gelatin/nano-hydroxyapatite (AGH)/bone marrow-derived mesenchymal stem cells (BMSCs). Physicochemical results showed that nano-hydroxyapatite (nHA) added in the bioink maintained its crystalline phase. In addition, an increase of viscosity, the improvement of compressive modulus (p < 0.01), and slow degradation rate (p < 0.01) were found after adding nHA. SEM showed cell stretched and attached well on the surface of the 3D printed construct. At day 7 after printing, the viability of GFs in AG was 94.80% ± 1.14%, while BMSC viability in AGH was 86.59% ± 0.75%. Polymerase chain reaction results indicated that the expression levels of ALP, RUNX-2, and OCN in BMSCs were higher in AGH than AG bioink (p < 0.01). After 8-week implantation into the dorsum of 6- to 8-week-old male athymic and inbred (BALB/c) nude mice, the cellular printed construct displayed a more integrated structure and better healing of subcutaneous tissue compared with the acellular printed construct. In conclusion, this 3D cell printed soft-hard construct exhibits favorable biocompatibility and has potential for alveolar ridge preservation. Impact statement Alveolar ridge resorption after tooth extraction has posed great difficulty in the subsequent restorative procedure. Clinically, to preserve the dimension of alveolar ridge, covering soft tissue healing and underlying bone formation is necessary after tooth extraction. Three-dimensional (3D) cell printing, which can distribute different biomaterials and cells with spatial control, provides a novel approach to develop a customized plug to put in the fresh socket to minimize bone resorption and improve gingiva growth. In this study, an integrated and heterogeneous soft-hard construct with lock-key structure was successfully developed using 3D cell printing. The physicochemical and biological properties were tested in vitro and in vivo. This 3D cell printed soft-hard construct will be a customized plug in alveolar ridge preservation in the future.

Uncarboxylated osteocalcin promotes osteogenesis and inhibits adipogenesis of mouse bone marrow-derived mesenchymal stem cells via the PKA-AMPK-SIRT1 axis

Osteoporosis is a bone disease characterized by reduced bone density, thin cortical bone and large gaps in the bone's honeycomb structure, which increases the risk of bone fragility. Uncarboxylated osteocalcin (unOC), a vitamin K-dependent bone protein, is known to regulate carbohydrate and energy metabolism. A previous study demonstrated that unOC promotes the differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs) into osteoblasts, but inhibits their differentiation into adipocytes. However, the underlying mechanism remains unknown. The present study showed that unOC regulated the differentiation potential of BMSCs via protein kinase A (PKA)/AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) signaling. SIRT1, a member of the sirtuin family with deacetylation functions, was upregulated by unOC in BMSCs. Transfection analyses with SIRT1 small interfering RNA indicated that the unOC-induced differentiation shift in BMSCs required SIRT1. Examination of SIRT1 downstream targets revealed that unOC regulated the acetylation levels of runt-related transcription factor (RUNX) 2 and peroxisome proliferator-activated receptor γ (PPARγ). Therefore, unOC inhibited adipogenic differentiation by PPARγ acetylation and promoted osteogenic differentiation by RUNX2 deacetylation. Moreover, phosphorylated PKA and AMPK protein levels increased after unOC treatment, which led to the upregulation of SIRT1. Western blot analysis with PKA and AMPK inhibitors indicated that the PKA-AMPK signaling pathway functioned upstream of SIRT1 and positively regulated SIRT1 expression. These findings led us to propose a model in which unOC regulated BMSC osteogenic differentiation through the PKA-AMPK-SIRT1 axis, giving evidence towards the therapeutic potential of unOC in osteoporosis treatment.

Resveratrol Pretreatment Improved Heart Recovery Ability of Hyperglycemic Bone Marrow Stem Cells Transplantation in Diabetic Myocardial Infarction by Down-Regulating MicroRNA-34a

AIM: To examine the effect of resveratrol (RSV) on bone marrow mesenchymal stem cells (BMSCs) under hyperglycemic conditions and on BMSCs transplantation in diabetic rats with myocardial infarction (MI).

METHODS:In vitro, BMSCs were isolated from 3-week-old male Sprague Dawley (SD) rats and cultured under hyperglycemic conditions for up to 28 days. Cell viability was analyzed by cell counting kit-8 (CCK-8) assays. The expression of miR-34a was measured by RT-qPCR. Western blotting was used to examine the protein expression of SIRT1, P21, P16, VEGF and HIF-1α. A senescence-associated β-galactosidase assay was used to examine the senescence level of each group. In vivo, a diabetes model was established by feeding rats a high-sugar and high-fat diet for 8 weeks, injecting the animals with streptozotocin (STZ) and continuing high-sugar and high-fat feeding for 4 additional weeks. Then, left anterior descending coronary artery (LAD) cessation was used to established the myocardial infarction (MI) models. Each group of rats was transplanted with differentially preconditioned BMSCs after myocardial infarction. Ultrasound was used to analyze cardiac function 1 and 3 weeks after the operation, and frozen heart sections were used for immunohistochemical analysis, Masson staining and CD31 measurement. In addition, ELISA analysis of serum cytokine levels was performed.

RESULTS: This study showed that the viability of BMSCs cultured under hyperglycemic conditions was decreased, the cells became senescent. Besides, an obviously increased in the expression of miR-34a was detected. Moreover, RSV preconditioning reduced the expression of miR-34a in BMSCs after high glucose stimulation and rejuvenated BMSCs under hyperglycemic conditions. Further analysis showed that the transplantation of RSV-BMSCs were benefit to heart recovery following infarction in diabetic rats, promoted proangiogenic factor release and increased arteriole and capillary densities.

CONCLUSION: RSV rejuvenated BMSCs after chronic hyperglycemia-induced senescence by interacting with miR-34a and optimized the therapeutic effect of BMSCs on diabetes with myocardial infarction.

Bone marrow-derived mesenchymal stem cells improve rat islet graft revascularization by upregulating ISL1

Revascularization of the islet transplant is a crucial step that defines the success rate of patient recovery. Bone marrow-derived mesenchymal stem cells (BMSCs) have been reported to promote revascularization; however, the underlying cellular mechanism remains unclear. Moreover, our liquid chromatography-tandem mass spectrometry results showed that BMSCs could promote the expression of insulin gene enhancer binding protein-1 (ISL1) in islets. ISL1 is involved in islets proliferation and plays a potential regulatory role in the revascularization of islets. This study identifies the ISL1 protein as a potential modulator in BMSCs-mediated revascularization of islet grafts. We demonstrated that the survival rate and insulin secretion of islets were increased in the presence of BMSCs, indicating that BMSCs promote islet revascularization in a coculture system and rat diabetes model. Interestingly, we also observed that the presence of BMSCs led to an increase in ISL1 and vascular endothelial growth factor A (VEGFA) expression in both islets and the INS-1 rat insulinoma cell line. In silico protein structure modeling indicated that ISL1 is a transcription factor that has four binding sites with VEGFA mRNA. Further results showed that overexpression of ISL1 increased both the abundance of VEGFA transcripts and protein accumulation, while inhibition of ISL1 decreased the abundance of VEGFA. Using a ChIP-qPCR assay, we demonstrated that direct molecular interactions between ISL1 and VEGFA occur in INS-1 cells. Together, these findings reveal that BMSCs promote the expression of ISL1 in islets and lead to an increase in VEGFA in islet grafts. Hence, ISL1 is a potential target to induce early revascularization in islet transplantation.

Transforming Growth Factor-β1 Enhances Mesenchymal Characteristics of Buffalo (Bubalus bubalis) Bone Marrow-Derived Mesenchymal Stem Cells

Bone marrow-derived mesenchymal stem cells (BMSCs) from livestock are valuable resources for animal reproduction and veterinary therapeutics. Previous studies have shown that BMSCs were prone to malignant transformation of mesenchymal-to-epithelial transition in vitro, which can cause many barriers to further application of BMSCs. The transforming growth factor β (TGF-β) signaling pathway has been widely studied as the most important signaling pathway involved in regulating mesenchymal features of BMSCs. However, the effects of the TGF-β signaling pathway on mesenchymal characteristics of buffalo BMSCs (bBMSCs) remain unclear. In the present study, the impacts of the growth factor, TGF-β1, on cell proliferation, apoptosis, migration, and karyotype of bBMSCs were tested. Besides, the effects of TGF-β1 on pluripotency, mesenchymal markers, and epithelial-to-mesenchymal transition (EMT)-related gene expression of bBMSCs were also examined. Results showed that the suitable concentration and time of TGF-β1 treatment (2 ng/mL and 24 hours) promoted cell proliferation and significantly reduced cell apoptosis (p < 0.05) in bBMSCs. The cell migration capacity and normal karyotype rate of bBMSCs were significantly (p < 0.05) improved under TGF-β1 treatment. The expression levels of pluripotency-related genes (Sox2 and Nanog) and mesenchymal markers (N-cadherin and Fn1) were significantly (p < 0.05) up-regulated under TGF-β1 treatment. Furthermore, TGF-β1 activated the EMT process, thereby contributing to significantly enhancing the expression levels of EMT-related genes (Snail and Slug) (p < 0.05), which in turn improved maintenance of the mesenchymal nature in bBMSCs. Finally, bBMSCs underwent self-transformation more easily and efficiently and exhibited more characteristics of mesenchymal stem cells under TGF-β1 treatment. This study provides theoretical guidance for elucidating the detailed mechanism of the TGF-β signaling pathway in mesenchymal feature maintenance of bBMSCs and is of significance to establish a stable culture system of bBMSCs.

Osthole enhances the immunosuppressive effects of bone marrow-derived mesenchymal stem cells by promoting the Fas/FasL system

Thanks to the advantages of easy harvesting and escape from immune rejection, autologous bone marrow‐derived mesenchymal stem cells (BMSCs) are promising candidates for immunosuppressive therapy against inflammation and autoimmune diseases. However, the therapy is still challenging because the immunomodulatory properties of BMSCs are always impaired by immunopathogenesis in patients. Because of its reliable and extensive biological activities, osthole has received increased clinical attention. In this study, we found that BMSCs derived from osteoporosis donors were ineffective in cell therapy for experimental inflammatory colitis and osteoporosis. In vivo and in vitro tests showed that because of the down‐regulation of Fas and FasL expression, the ability of osteoporotic BMSCs to induce T‐cell apoptosis decreased. Through the application of osthole, we successfully restored the immunosuppressive ability of osteoporotic BMSCs and improved their treatment efficacy in experimental inflammatory colitis and osteoporosis. In addition, we found the immunomodulatory properties of BMSCs were enhanced after osthole pre‐treatment. In this study, our data highlight a new approach of pharmacological modification (ie osthole) to improve the immune regulatory performance of BMSCs from a healthy or inflammatory microenvironment. The development of targeted strategies to enhance immunosuppressive therapy using BMSCs may be significantly improved by these findings.

Naringenin promotes SDF-1/CXCR4 signaling pathway in BMSCs osteogenic differentiation

INTRODUCTION

Naringenin, a dihydro-flavonoid compound that shows chemotactic activity, may have a good application prospect in repairing bone tissue, but its specific mechanism in bone regeneration, especially the osteogenic differentiation of stem cells, needs for a further study. The aim of this study was to investigate the effect of naringenin on the osteogenic differentiation and its roles in the C-X-C chemokine receptor type 4/stromal cell-derived factor 1 (SDF-1/CXCR4) signal pathway of bone marrow-derived mesenchymal stem cells (BMSCs).

MATERIAL AND METHODS

BMSCs were harvested from the femurs and tibias of 4-to-6-week-old male Sprague-Dawley rats. Cell Counting kit-8 assay was used to determine cytotoxicity of naringenin. Alkaline phosphatase (ALP) activity was measured in cell's precipitates and alizarin-red staining was performed to determine the osteogenic differentiation capacity of the BMSCs. Real-time polymerase chain reaction, enzyme-linked immunosorbent assay and western blotting were adopted to determine the expression of genes and proteins.

RESULTS

The cellular morphology was spindle-shaped, and arranged in radial and whorled patterns. The flow cytometric analysis have confirmed the presence of characteristic surface proteins in the harvested BMSCs. Different concentrations (0-200 μg/ml) of naringenin have no influence on the viability and proliferation rate of the BMSCs. The highest ALP activity was found at culture day 7 and 9 when the concentration of naringenin was 75 and 100 μg/ml. Positive red or dark red stained cells with mineralized nodules can be observed on day 14. The expression of ALP, Runt-related transcription factor 2, CXCR4 and SDF-1a at the gene and protein levels in naringenin-treated cells were significantly higher than those in the control cells. Moreover, AMD3100, an inhibitor of CXCR4, suppressed the expression of the studied genes and proteins.

CONCLUSIONS

Naringenin does not show toxic effect on BMSCs. Naringenin promotes the expression of the SDF-1a gene and protein via the SDF-1/CXCR4 signaling pathway. A better understanding of the mechanisms of naringenin action would be helpful for developing specific therapeutic strategies to improve bone regeneration after injuries.

Macrophages activated by akermanite/alginate composite hydrogel stimulate migration of bone marrow-derived mesenchymal stem cells

Akermanite (Aker) has been widely used for bone regeneration through regulating osteogenesis of bone marrow-derived mesenchymal stem cells (BMSCs). Previously, we developed an injectable Aker/sodium alginate (Aker/SA) hydrogel to facilitate bone regeneration. However, the effect of this injectable hydrogel on the in vivo response, particularly the inflammatory response, has not been fully understood. Here, to elucidate the response following the implantable of Aker/SA hydrogel, we investigated the interaction among Aker/SA hydrogel, inflammatory cells and cells involved in bone regeneration (BMSCs). Specifically, we cultured macrophages (RAW 264.7 cell line) with the extract liquid of Aker/SA and assessed their phenotypic changes. Subsequently, BMSCs (2*10^5 cells per 24 well) were cultured with different conditioned media including that of Aker/SA hydrogel-activated macrophages to investigate their effect on cell migration. Finally, Aker/SA hydrogel was injected subcutaneously (1*10^6 cells per ml) in rat to verify its effect in vivo. The in vitro results indicated that Aker/SA hydrogel activated macrophages towards M2 phenotype and stimulated macrophages to express anti-inflammatory factors. In addition, the conditioned medium collected from Aker-activated macrophages could accelerate the migration of BMSCs in 24h. Consistent with the in vitro results, when the Aker/SA hydrogel was injected subcutaneously, more M2 macrophages could be observed than when the SA solution was injected after 7 days. Besides, when BMSCs were delivered via subcutaneous injection, more BMSCs were recruited by the Aker/SA hydrogel than the SA solution. All these results suggest that the Aker/SA hydrogel can modulate the immune environment at the implantation site and subsequently recruit BMSCs, which can be one of the mechanisms through which the Aker/SA hydrogel accelerates new bone formation.

Exosome-Encapsulated microRNA-127-3p Released from Bone Marrow-Derived Mesenchymal Stem Cells Alleviates Osteoarthritis Through Regulating CDH11-Mediated Wnt/β-Catenin Pathway

Objective

Exosome-encapsulated microRNAs (miRNAs) are being considered as either diagnostic or predictive markers in different types of diseases. Here, we discussed the effects of exosome-encapsulated miR-127-3p from bone marrow-derived mesenchymal stem cells (BM-MSCs) on osteoarthritis (OA).

Methods

BM-MSCs and primary chondrocytes were isolated from Sprague Dawley rats. IL-1β was utilized to treat chondrocytes to mimic an OA in vitro model, and exosomes extracted from BM-MSCs were utilized to treat chondrocytes so as to verify their protective effects on OA. Through online website prediction and experiments confirmation, we found the most significantly enriched miRNA in exosomes and elucidated the effect of this miRNA on the therapeutic effect of exosomes by interfering with its expression. Also, the genes targeted by the miRNA and the involved pathway were also found through bioinformatics analysis and experimental research, thereby probing into the protective mechanism of exosomes on chondrocytes.

Results

Exosomes derived from BM-MSCs restricted the IL-1β-induced chondrocytes damage. miR-127-3p was found to be enriched in exosomes, and the protective effect of exosomes was reversed by miR-127-3p inhibition. miR-127-3p targeted CDH11, and overexpressed CDH11 in chondrocytes weakened the therapeutic effect of exosomes. IL-1β treatment resulted in the activation of the Wnt/β-catenin pathway in chondrocytes. Exosomes treatment could inhibit the activation of this pathway, and overexpressed CDH11 reversed the inhibitory effect of exosomes on this pathway.

Conclusion

This study suggests that exosomal miR-127-3p derived from BM-MSCs inhibits CDH11 in chondrocytes, thereby blocking the Wnt/β-catenin pathway activation and relieving chondrocyte damage in OA.

Bone Marrow Mesenchymal Stem Cells-Derived Extracellular Vesicles Promote Proliferation, Invasion and Migration of Osteosarcoma Cells via the lncRNA MALAT1/miR-143/NRSN2/Wnt/β-Catenin Axis

Introduction

Osteosarcoma is a malignant primary bone tumor. Bone marrow-derived mesenchymal stem cells-derived extracellular vesicles (BMSC-EVs) bear repair function for bone and cartilage. This study investigated the mechanism of BMSC-EVs in osteosarcoma cell proliferation, migration and invasion.

Methods

BMSC-EVs were isolated and identified. The effects of different concentrations of EVs on osteosarcoma cell proliferation, migration and invasion were evaluated. LncRNA MALAT1 expression in osteosarcoma cells was detected. BMSCs were transfected with si-MALAT1 or si-NC. The binding relationships between MALAT1 and miR-143, and miR-143 and NRSN2 were verified. Levels of NRSN2 and Wnt/β-catenin pathway key proteins were detected. miR-143 mimic was transfected into EVs-treated osteosarcoma cells. Nude mice were injected with MG63 cells to verify the effect of EVs on osteosarcoma growth in vivo.

Results

BMSC-EVs facilitated proliferation, invasion and migration of osteosarcoma cells. BMSC-EVs carried MALAT1 into osteosarcoma cells. BMSC-EVs-treated osteosarcoma cells showed increased MALAT1 and NRSN2 expressions, decreased miR-143 expression, and activated Wnt/β-catenin pathway. miR-143 mimic or si-MALAT1 reversed the effects of BMSC-EVs on osteosarcoma cells. In vivo experiment confirmed that BMSC-EVs promoted tumor growth in nude mice.

Discussion

BMSC-EVs promoted proliferation, invasion and migration of osteosarcoma cells via the MALAT1/miR-143/NRSN2/Wnt/β-catenin axis. This study might offer new insights into osteosarcoma management.

[Yanghe Pingchuan granule promotes BMSCs homing in asthmatic rats by upregulating miR-139-5p and downregulating Notch1/Hes1 pathway]

OBJECTIVE

To observe the effect of Yanghe Pingchuan (YHPC) granule on miR-139-5p, Notch1/Hes1 pathway and homing of bone marrow-derived mesenchymal stem cells (BMSCs) in asthmatic rats.

METHODS

Fifty SD rats were randomized divided into normal control (NC) group, asthmatic model group, BMSCs transplantation group, BMSCs + dexamethasone (0.0625 mg/kg daily) group, and BMSCs+YHPC granule (3.5 g/kg daily) group. In all but the normal control group, asthmatic rat models were established by ovalbumin challenge, and BMSCs (1×10⁶/mL) transplantation via the tail vein was performed in the latter 3 groups on last day of ovalbumin challenge. In all the groups, lung pathologies of the rats were evaluated using HE staining after the treatments. Flow cytometry was employed to detect pulmonary expression of CXCR4 protein, and ELISA was used to determine the expressions of interferon-γ (IFN-γ) and interleukin-4 (IL-4) in the lung tissue. The expressions of CXCR4, Notch1 and Hes1 in bronchial epithelial cells was examined using immunofluorescence assay. RT-PCR was used to detect the expressions of miR-139-5p, Notch1, Jagged1, RBP-J and Hes1 mRNAs, and the protein expressions of Notch1, Jagged1 and Hes1 were detected with Western blotting.

RESULTS

Compared with the normal control rats, the asthmatic rats exhibited significantly increased expressions of CXCR4, IL-4, Notch1, Jagged1, RBP-J, and Hes1 mRNA and Notch1, Jagged1, and Hes1 proteins and lowered expressions of INF-γ mRNA and miR-139-5p in the lung tissues (P < 0.05 or 0.01). Compared with those in the asthmatic model group, the mRNA expressions of CXCR4, IFN-γ, and miR-139-5p increased and the expressions of IL-4, Notch1, Jagged1, RBP-J, and Hes1 mRNA and Notch1, Jagged1, and Hes1 proteins decreased significantly in the 3 groups with BMSCs transplantation (P < 0.05 or 0.01). The rats in BMSCs+YHPC granule group showed significantly higher CXCR4, IFN-γ, and miR-139-5p mRNA expressions and lower IL-4 and Notch1 mRNA expressions than those in BMSCs transplantation group (P < 0.05).

CONCLUSIONS

YHPC granule can enhance the inhibitory effect of BMSCs homing on Th2 inflammatory response in asthmatic rats by up-regulating miR-139-5p and down-regulating Notch1/Hes1 pathway.

Transplantation of bone marrow-derived mesenchymal stem cells with silencing of microRNA-138 relieves pelvic organ prolapse through the FBLN5/IL-1β/elastin pathway

Nondegradable transvaginal polypropylene meshes for treating pelvic organ prolapse (POP) are now generally unavailable or banned due to serious adverse events. New tissue engineering approaches combine degradable scaffolds with mesenchymal stem/stromal cells from human endometrium (eMSC). In this study, we investigate effect of microRNA-138 (miR-138) regulation on bone marrow-derived mesenchymal stem cells (BMSCs) and the efficacy of BMSC transplantation therapy in a rat POP model. We first identified FBLN5 as a target of miR-138. miR-138, fibulin-5 (FBLN5), interleukin-1β (IL-1β), and elastin expression in uterosacral ligament of POP patients and controls were detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. After isolation and identification, BMSCs were treated to alter their expression of miR-138 or FBLN5. Proliferation of BMSCs was analyzed by CCK-8. After establishing the rat pelvic floor dysfunction (PFD) model, we evaluated efficacy of BMSC injection by applying leak point pressure (LPP) and the conscious cystometry (CMG) tests. miR-138 inhibition resulted in increased viability of BMSCs and elevated their secretion of elastin, while downregulating IL-1β expression. BMSCs with inhibited miR-138 improved LPP and conscious CMG results in vivo. Taken together, miR-138 could be a potential therapeutic target for treating POP in conjunction with tissue engineering.

Bone marrow mesenchymal stem cells inhibit cardiac hypertrophy by enhancing FoxO1 transcription

Bone marrow-derived mesenchymal stem cells (BMSCs) have therapeutic potential for certain heart diseases. Previous studies have shown that stem cells inhibit cardiac hypertrophy; however, it is necessary to explore the mechanisms underlying this effect. This study aimed to investigate the possible mechanism underlying the inhibitory effect of BMSCs on cardiomyocyte hypertrophy. We induced cardiomyocyte hypertrophy in cultured rat cells through isoproterenol (ISO) treatment with or without BMSC coculture. A microarray was performed to analyze messenger RNA expression in response to ISO treatment and BMSC coculture. Pathway enrichment analysis showed that the expression of differential genes was closely related to the 5'-adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and that the expression of forkhead box O 1 (FoxO1) was significantly increased in the presence of BMSCs. Furthermore, we determined the expression levels of p-AMPK/AMPK and p-FoxO1/FoxO1 by western blot analysis. The expression of p-AMPK/AMPK was upregulated, whereas that of p-FoxO1/FoxO1 was downregulated upon coculturing with BMSCs. The AMPK-specific antagonist Compound C inhibited the downregulation of p-FoxO1/FoxO1 induced by the BMSC coculture. Furthermore, treatment with the specific FoxO1 antagonist AS1842856 reduced the inhibitory effects of BMSCs on cardiomyocyte hypertrophy in vivo and in vitro. Our present study demonstrates the inhibition of cardiomyocyte hypertrophy by BMSCs, which occurs partly through the AMPK-FoxO1 signaling pathway.

Magnet-targeted delivery of bone marrow-derived mesenchymal stem cells improves therapeutic efficacy following hypoxic-ischemic brain injury

Stem cell transplantation may represent a feasible therapeutic option for the recovery of neurological function in children with hypoxic-ischemic brain injury; however, the therapeutic efficacy of bone marrow-derived mesenchymal stem cells largely depends on the number of cells that are successfully transferred to the target. Magnet-targeted drug delivery systems can use a specific magnetic field to attract the drug to the target site, increasing the drug concentration. In this study, we found that the double-labeling using superparamagnetic iron oxide nanoparticle and poly-L-lysine (SPIO-PLL) of bone marrow-derived mesenchymal stem cells had no effect on cell survival but decreased cell proliferation 48 hours after labeling. Rat models of hypoxic-ischemic brain injury were established by ligating the left common carotid artery. One day after modeling, intraventricular and caudal vein injections of 1 × 10⁵ SPIO-PLL-labeled bone marrow-derived mesenchymal stem cells were performed. Twenty-four hours after the intraventricular injection, magnets were fixed to the left side of the rats’ heads for 2 hours. Intravoxel incoherent motion magnetic resonance imaging revealed that the perfusion fraction and the diffusion coefficient of rat brain tissue were significantly increased in rats treated with SPIO-PLL-labeled cells through intraventricular injection combined with magnetic guidance, compared with those treated with SPIO-PLL-labeled cells through intraventricular or tail vein injections without magnetic guidance. Hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining revealed that in rats treated with SPIO-PLL-labeled cells through intraventricular injection under magnetic guidance, cerebral edema was alleviated, and apoptosis was decreased. These findings suggest that targeted magnetic guidance can be used to improve the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for hypoxic-ischemic brain injury. This study was approved by the Animal Care and Use Committee of The Second Hospital of Dalian Medical University, China (approval No. 2016-060) on March 2, 2016.

Comparison of concentrated fresh mononuclear cells and cultured mesenchymal stem cells from bone marrow for bone regeneration

Autologous bone marrow mononuclear cell (BMMNC) transplantation has been widely studied in recent years. The fresh cell cocktail in BMMNCs, without going through the in vitro culture process, helps to establish a stable microenvironment for osteogenesis, and each cell type may play a unique role in bone regeneration. Our study compared the efficacy of concentrated fresh BMMNCs and cultured bone marrow‐derived mesenchymal stem cells (BMSCs) in Beagle dogs for the first time. Fifteen‐millimeter segmental bone defects were created in the animals' tibia bones. In BMMNCs group, the defects were repaired with concentrated fresh BMMNCs combined with β‐TCP (n = 5); in cultured BMSC group, with in vitro cultured and osteo‐induced BMSCs combined with β‐TCP (n = 5); in scaffold‐only group, with a β‐TCP graft alone (n = 5); and in blank group, nothing was grafted (n = 3). The healing process was monitored by X‐rays and single photon emission computed tomography. The animals were sacrificed 12 months after surgery and their tibias were harvested and analyzed by microcomputed tomography and hard tissue histology. Moreover, the microstructure, chemical components, and microbiomechanical properties of the regenerated bone tissue were explored by multiphoton microscopy, Raman spectroscopy and nanoindentation. The results showed that BMMNCs group promoted much more bone regeneration than cultured BMSC group. The grafts in BMMNCs group were better mineralized, and they had collagen arrangement and microbiomechanical properties similar to the contralateral native tibia bone. These results indicate that concentrated fresh bone marrow mononuclear cells may be superior to in vitro expanded stem cells in segmental bone defect repair.

Role of Curcuminoids and Tricalcium Phosphate Ceramic in Rat Spinal Fusion

Despite considerable research effort, there is a significant need for safe agents that stimulate bone formation. Treatment of large or complex bone defects remains a challenge. Implantation of small molecule-induced human bone marrow-derived mesenchymal stromal cells (hBMSCs) on an appropriate tricalcium phosphate (TCP) scaffold offers a robust system for noninvasive therapy for spinal fusion. To show the efficacy of this approach, we identified a small molecule curcuminoid that when combined with TCP ceramic in the presence of hBMSCs selectively induced growth of bone cells: after 8- or 25-day incubations, alkaline phosphatase was elevated. Treatment of hBMSCs with curcuminoid 1 and TCP ceramic increased osteogenic target gene expression (i.e., Runx2, BMP2, Osteopontin, and Osteocalcin) over time. In the presence of curcuminoid 1 and TCP ceramic, osteogenesis of hBMSCs, including proliferation, differentiation, and mineralization, was observed. No evidence of chondrogenic or adipogenic potential using this protocol was observed. Transplantation of curcuminoid 1-treated hBMSC/TCP mixtures into the spine of immunodeficient rats showed that it achieved spinal fusion and provided greater stability of the spinal column than untreated hBMSC-TCP implants or TCP alone implants. On the basis of histological analysis, greater bone formation was associated with curcuminoid 1-treated hBMSC implants manifested as contiguous growth plates with extensive hematopoietic territories. Stimulation of hBMSCs by administration of small molecule curcuminoid 1 in the presence of TCP ceramic afforded an effective noninvasive strategy that increased spinal fusion repair and provided greater stability of the spinal column after 8 weeks in immunodeficient rats. Impact statement Bone defects only slowly regenerate themselves in humans. Current procedures to restore spinal defects are not always effective. Some have side effects. In this article, a new method to produce bone growth within 8 weeks in rats is presented. In the presence of tricalcium phosphate ceramic, curcuminoid-1 small molecule-stimulated human bone marrow-derived mesenchymal stromal cells showed robust bone cell growth in vitro. Transplantation of this mixture into the spine showed efficient spinal fusion in rats. The approach presented herein provides an efficient biocompatible scaffold for delivery of a potentially clinically useful system that could be applicable in patients.

Role of bone marrow-derived mesenchymal stem cells in alleviating pulmonary epithelium damage and extracellular matrix remodeling in a rat model of lung fibrosis induced by amiodarone

The therapeutic role of mesenchymal stem cells (MSCs) in cases of amiodarone (AD) induced pulmonary fibrosis (PF) has not been well studied. Also, the period required by MSCs to attain full therapeutic effectiveness has not yet been assessed. We investigated the potential curative effect of bone marrow-derived MSCs (BM-MSCs) and conditioned media (CM) from BM-MSCs on AD induced PF by focusing on pulmonary epithelium injury and repair, and extracellular matrix (ECM) remodeling. We used 64 Wistar rats divided into eight groups: negative control group; PF group; three PF groups treated with BM-MSCs for 1, 2 or 4 months; and three PF groups treated with CM for 1, 2 and 4 months. Serum levels of Clara cell secretory protein (CC16) and keratinocyte growth factor (KGF) were measured. Gene expression of type I collagen (COL1A1) and connective tissue growth factor (CTGF) was evaluated in pulmonary tissue. Treatment of PF challenged rats with BM-MSCs or CM caused reduced CC16 levels, increased KGF levels, reduced expression of COL1A1 and CTGF, histological improvement following lung injury, and decreased collagen accumulation. Treatment with BM-MSCs exhibited greater amelioration of PF than CM. BM-MSCs or CM treatment for 2 and 4 months exhibited better resolution of fibrosis than treatment for 1 month. BM-MSCs are promising for treating PF due to their attenuation of ECM deposition in addition to alleviating pulmonary epithelium damage and initiating its repair.

Three-dimensional silk fibroin scaffolds incorporated with graphene for bone regeneration

Porous three-dimensional (3D) silk fibroin (SF) scaffolds were widely applied for bone regeneration and showed excellent biocompatibility and biodegradability. Recently graphene was developed for bone scaffolds due to its osteogenic properties. Thus, we combine the SF and graphene to improve the osteogenic properties of SF scaffolds. In our study, we explored the incorporation of SF scaffolds with graphene to develop osteogenic scaffolds capable of accelerating bone formation. The 3D SF scaffolds were fabricated with different contents of graphene (0, 0.5, and 2%). Fluorescence images showed that the graphene nanosheets were homogeneously dispersed in the SF scaffolds. The addition of graphene affected the microarchitecture of the scaffolds. The G/SF scaffolds were cocultured with rat bone marrow-derived mesenchymal stem cells (rBMSCs) for 21 days. The cell morphology and cell proliferation study suggested that 0 and 0.5% G/SF scaffolds displayed good cell proliferation. In addition, immunofluorescent staining (e.g., osteonectin, osteopontin, and osteocalcin) and ALP activities indicated that the osteogenic properties was more actively exhibited on 0.5% G/SF scaffolds compared with the other groups. Our results indicated that SF scaffolds incorporated with graphene could be an appropriate scaffold for bone tissue engineering.

Enhanced recruitment and hematopoietic reconstitution of bone marrow-derived mesenchymal stem cells in bone marrow failure by the SDF-1/CXCR4

Aplastic anemia (AA) is a bone marrow failure disease. It is difficult to treat AA, and in addition, relapses are common because of its complex disease pathogenesis. Allogeneic bone marrow-derived mesenchymal stem cells (BMSCs) infusion is an effective and safe treatment option for the AA patients. However, it found that BMSCs infusion in AA patients is less than 30% effective. Therefore, the key to improve the efficacy of BMSCs treatment in these patients is to enhance their homing efficiency to the target sites. Studies have shown that stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) axis plays an important role in promoting BMSCs homing. In this study, human BMSCs were transduced with lentivirus stably expressing CXCR4-BMSCs. Transduced BMSCs resemble normal BMSCs in many ways. Migration ability of CXCR4-BMSCs toward SDF-1 was increased because of the overexpression of CXCR4. In the mice with bone marrow failure, the migration and colonization ability of CXCR4-BMSCs to the bone marrow was significantly improved as seen by IVIS imaging and FACS. The SDF-1 level in the bone marrow failure mice was significantly higher than in the normal mice. Thus, from our study, it is clear that after CXCR4-BMSCs were infused into mice with bone marrow failure, SDF-1 interacted with CXCR4 receptor, leading cells to migrate and colonize to bone marrow. Because of the high SDF-1 expression in mouse bone marrow and CXCR4 receptor expression in cells, BMSCs homing was increased.

Role of bone marrow-derived mesenchymal stem cell defects in CD8+ CD28- suppressor T-lymphocyte induction in patients with immune thrombocytopenia and associated mechanisms

Many immune dysfunctions participate in immune thrombocytopenia (ITP) pathogenesis, including numeric and functional defects in suppressor T (Ts) cells and immune-regulation abnormalities in mesenchymal stem cells (MSCs). Recent studies showed that MSCs can promote Ts cell differentiation. Thus, we compared the Ts cell induction ability of bone marrow-derived MSCs (BM-MSCs) between patients with ITP and normal controls (NCs), and examined the mechanism of this difference. Co-culture of CD8⁺ T cells with BM-MSCs revealed that BM-MSCs elevated Ts cell percentage and function, but the efficiency was lower in patients with ITP than in NCs. Blockade experiments showed that blockade of interleukin 6 (IL-6) partially reversed Ts cell induction by BM-MSCs. Addition of exogenous IL-6 down-regulated Ts cell apoptosis. Moreover, BM-MSCs enhanced IL-10 secretion and inhibition ability of Ts cells. IL-6 secretion, regulatory abilities of IL-10 expression in Ts cells, and the enhanced efficiency of Ts cells inhibition function by BM-MSCs were all decreased in patients with ITP. All-trans retinoic acid preconditioning promoted BM-MSC induction of Ts cell percentages and umbilical cord-derived (UC) MSCs efficiently improved ITP Ts cell numbers and dysfunction. In conclusion, defects of BM-MSCs in Ts cell induction are involved in ITP pathogenesis, and exogenous UC-MSCs may be useful for ITP therapy.

Rat Bone Marrow-Derived Mesenchymal Stem Cells Promote the Migration and Invasion of Colorectal Cancer Stem Cells

Background

Colorectal cancer is one of the most common cancers and the second leading cause of cancer-related deaths worldwide. Targeting cancer stem cells (CSCs) may be a novel strategy for the treatment of colorectal cancer. Previous studies have shown that bone marrow-derived MSCs (BM-MSCs) promote tumor growth and metastasis. However, the role of rat BM-MSCs in the biological behaviors of colorectal CSCs remains unclear until now.

Materials and Methods

BM-MSCs were isolated from rats and characterized. CSCs were enriched from HCT116 cells using the microsphere culture method, and the microspheres incubated for at least 10 passages were termed HCT116-CSCs that were characterized. The effects of rat BM-MSCs on migration and invasion of HCT116-CSCs were examined using transwell migration and invasion assays and xenograft tumor growth assay.

Results

Rat BM-MSCs appeared typical stem cell morphology. Flow cytometry revealed positive CD29 and CD44 expression in rat BM-MSCs at passage 3, and rat BM-MSCs were found to differentiate into osteocytes following incubation in osteogenic induction medium. Microscopy, flow cytometric detection of stem cell surface markers, colony-formation assay and transwell migration and invasion assays characterized the successful preparation of HCT116-CSCs, and subcutaneous injection of HCT116-CSCs produced xenograft tumors in nude mice, while HE staining of the xenograft tumors displayed cancer specimen shapes. Transwell migration and invasion assays showed that rat BM-MSCs promoted the migration and invasion of HCT116-CSCs, and injection of rat BM-MSCs was found to promote the growth of the mouse xenograft tumor derived from HCT116-CSCs.

Conclusion

Rat BM-MSCs promote the migration and invasion of colorectal CSCs, and colorectal CSCs may be a potential target for the therapy against colorectal cancer.

Ultrasmall Superparamagnetic Iron Oxide Labeled Silk Fibroin/Hydroxyapatite Multifunctional Scaffold Loaded With Bone Marrow-Derived Mesenchymal Stem Cells for Bone Regeneration

Numerous tissue-engineered constructs have been investigated as bone scaffolds in regenerative medicine. However, it remains challenging to non-invasively monitor the biodegradation and remodeling of bone grafts after implantation. Herein, silk fibroin/hydroxyapatite scaffolds incorporated with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles were successfully synthesized, characterized, and implanted subcutaneously into the back of nude mice. The USPIO labeled scaffolds showed good three-dimensional porous structures and mechanical property, thermal stability for bone repair. After loaded with bone marrow-derived mesenchymal stem cells (BMSCs), the multifunctional scaffolds promoted cell adhesion and growth, and facilitated osteogenesis by showing increased levels of alkaline phosphatase activity and up-regulation of osteoblastic genes. Furthermore, in vivo quantitative magnetic resonance imaging (MRI) results provided valuable information on scaffolds degradation and bone formation simultaneously, which was further confirmed by computed tomography and histological examination. These findings demonstrated that the incorporation of USPIO into BMSCs-loaded multifunctional scaffold system could be feasible to noninvasively monitor bone regeneration by quantitative MRI. This tissue engineering strategy provides a promising tool for translational application of bone defect repair in clinical scenarios.

Age-Related Regeneration of Osteochondral and Tibial Defects by a Fibrin-Based Construct in vivo

Tissue-biomaterial interactions in different microenvironments influence significantly the repair and regeneration outcomes when a scaffold or construct is implanted. In order to elucidate this issue, a fibrin gel filled macroporous fibrin scaffold (fibrin-based scaffold) was fabricated by loading fibrinogen via a negative pressure method, following with thrombin crosslinking. The macroporous fibrin scaffold exhibited a porous structure with porosity of (88.1 ± 1.3)%, and achieved a modulus of 19.8 ± 0.4 kPa at a wet state after fibrin gel filling, providing a suitable microenvironment for bone marrow-derived mesenchymal stem cells (BMSCs). The in vitro cellular culture revealed that the fibrin-based scaffold could support the adhesion, spreading, and proliferation of BMSCs in appropriate cell encapsulation concentrations. The fibrin-based scaffolds were then combined with BMSCs and lipofectamine/plasmid deoxyribonucleic acid (DNA) encoding mouse-transforming growth factor β1 (pDNA-TGF-β1) complexes to obtain the fibrin-based constructs, which were implanted into osteochondral and tibial defects at young adult rabbits (3 months old) and aged adult rabbits (12 months old) to evaluate their respective repair effects. Partial repair of osteochondral defects and perfect restoration of tibial defects were realized at 18 weeks post-surgery for the young adult rabbits, whereas only partial repair of subchondral bone and tibial bone defects were found at the same time for the aged adult rabbits, confirming the adaptability of the fibrin-based constructs to the different tissue microenvironments by tissue-biomaterial interplays.

Mesenchymal stem cell therapy alleviates the neuroinflammation associated with acquired brain injury

Ischemic stroke and traumatic brain injury (TBI) comprise two particularly prevalent and costly examples of acquired brain injury (ABI). Following stroke or TBI, primary cell death and secondary cell death closely model disease progression and worsen outcomes. Mounting evidence indicates that long‐term neuroinflammation extensively exacerbates the secondary deterioration of brain structure and function. Due to their immunomodulatory and regenerative properties, mesenchymal stem cell transplants have emerged as a promising approach to treating this facet of stroke and TBI pathology. In this review, we summarize the classification of cell death in ABI and discuss the prominent role of inflammation. We then consider the efficacy of bone marrow–derived mesenchymal stem/stromal cell (BM‐MSC) transplantation as a therapy for these injuries. Finally, we examine recent laboratory and clinical studies utilizing transplanted BM‐MSCs as antiinflammatory and neurorestorative treatments for stroke and TBI. Clinical trials of BM‐MSC transplants for stroke and TBI support their promising protective and regenerative properties. Future research is needed to allow for better comparison among trials and to elaborate on the emerging area of cell‐based combination treatments.

Epidermal growth factor stimulates exosomal microRNA-21 derived from mesenchymal stem cells to ameliorate aGVHD by modulating regulatory T cells

Regulatory T cells (Tregs), a subset of CD4⁺ T cells, may exert inhibitory effects on alloimmune responses including acute graft-versus-host disease (aGVHD), and several microRNAs are implicated in the pathophysiological process of GVHD. Therefore, we aimed in the present study to characterize the functional relevance of epidermal growth factor (EGF)-stimulated microRNA-21 (miR-21) in regulating bone marrow-derived mesenchymal stem cells (BMSCs) in a mouse model of aGVHD. We first isolated and cultured BMSCs and Tregs. Then, we examined effects of miR-21 knockdown or overexpression and EGF on cell activities of BMSCs and the expression of PTEN, Foxp3, AKT phosphorylation, and extent of c-jun phosphorylation by gain- and loss-of-function approaches. The results showed that miR-21 promoted the proliferation, invasion, and migration of BMSCs. Furthermore, miR-21 in BMSCs-derived exosomes inhibited PTEN, but enhanced AKT phosphorylation and Foxp3 expression in Tregs. In addition, EGF enhanced c-jun phosphorylation to elevate the miR-21 expression. Furthermore, EGF significantly increased the efficacy of BMSCs in a mouse model of aGVHD, manifesting in reduced IFN-γ expression and lesser organ damage. Moreover, EGF treatment promoted the Foxp3 expression of Tregs in BMSCs-treated aGVHD mice. Taken together, EGF induced the BMSCs-derived exosomal miR-21 expression, which enhanced Foxp3 expression in Tregs, thereby improving the therapeutic effect of BMSCs on aGVHD.

TRAF3, a Target of MicroRNA-363-3p, Suppresses Senescence and Regulates the Balance Between Osteoblastic and Adipocytic Differentiation of Rat Bone Marrow-Derived Mesenchymal Stem Cells

Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts or adipocytes, and an imbalance between adipogenesis and osteogenesis causes age-related bone loss. In this study, we determined the influence of tumor necrosis factor receptor-associated factor 3 (TRAF3) on senescence and osteoblastic and adipocytic differentiation of rat BMSCs. TRAF3 expression increased during osteogenic differentiation but decreased during adipocytic differentiation of rat BMSCs, and compared with day 0 cultures, on day 14, the differences were significant. Overexpression of TRAF3 significantly promoted BMSC osteogenic differentiation and suppressed adipogenic differentiation and senescence. Furthermore, Traf3 was determined to be a target gene of miR-363-3p in BMSCs, and TRAF3 expression in BMSCs was reduced by miR-363-3p overexpression. This overexpression attenuated the effects of TRAF3 on BMSC adipogenic differentiation, osteogenic differentiation, and senescence. Taken together, these results uncovered the mechanism by which TRAF3 promotes BMSC osteogenic differentiation and suppresses adipogenic differentiation and senescence, indicating that the miR-363-3p-TRAF3 axis might be a novel therapeutic target for BMSC-based bone tissue engineering in osteoporosis.

Icariin promotes osteogenic differentiation of BMSCs by upregulating BMAL1 expression via BMP signaling

Increasing research has demonstrated that expression of brain and muscle ARNT‑like 1 (BMAL1) and other circadian clock genes can be regulated by drugs and toxicants. We previously demonstrated that icariin, extracted from Herba Epimedii, sromotes osteogenic differentiation. However, the mechanism underlying the association between icariin and BMAL1 in osteogenic differentiation of bone marrow‑derived mesenchymal stem cells (BMSCs) remains unclear. The present study was designed with an aim to clarify the association between icariin and BMAL1 in osteogenic differentiation of BMSCs. The Cell Counting Kit‑8 assay was used to evaluate cell proliferation. The expression of bone morphogenetic protein 2 (BMP2), RUNX family transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OC) and BMAL1 in BMSCs was evaluated by reverse transcription‑quantitative PCR and western blotting. ALP and Alizarin red S (ARS) staining were also performed. Icariin promoted BMSC proliferation, and upregulated expression of osteogenic genes and BMAL1. In addition, expression of the osteogenic genes BMP2, RUNX2, ALP and OC were upregulated by BMAL1 overexpression. Furthermore, we confirmed that BMAL1 deficiency suppressed osteogenic differentiation in BMSCs. Finally, ARS staining of BMAL1‑/‑ BMSCs revealed that BMAL1 was an essential intermediary in matrix mineralization during osteogenic differentiation. In conclusion, these results demonstrated that icariin promoted osteogenic differentiation through BMAL1‑BMP2 signaling in BMSCs. The present study thus described a novel target of icariin that has potential applications in the treatment of osteogenic disorders.

Accelerating bone defects healing in calvarial defect model using 3D cultured bone marrow-derived mesenchymal stem cells on demineralized bone particle scaffold

Bone defects are usually difficult to be regenerated due to pathological states or the size of the injury. Researchers are focusing on tissue engineering approaches in order to drive the regenerative events, using stem cells to regenerate bone. The purpose of this study is to evaluate the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) on biologically derived Gallus gallus domesticus-derived demineralized bone particle (GDD) sponge. The sponges were prepared by freeze-drying method using 1, 2, and 3 wt% GDD and cross-linked with glutaraldehyde. The GDD sponge was characterized using scanning electron microscopy, compressive strength, porosity, and Fourier transform infrared. The potential bioactivity of the sponge was evaluated by osteogenic differentiation of BMSCs using 3(4, dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and quantifying alkaline phosphatase (ALP) activity. in vivo experiments were evaluated through a micro-computerized tomography (μ-CT) and histological assays. The analysis confirmed that an increase in the concentration of the GDD in the sponge leads to a higher bone formation and deposition in rat calvarial defects. Histological assay results were in line with μ-CT. The results reported in this study demonstrated the potential application of GDD sponges as osteoinductor in bone tissue engineering in pathological or nonunion bone defects.