Mesenchymal stem cells facilitate fracture repair in an alcohol-induced impaired healing model

Exogenously delivered iPSCs disrupt the natural repair response of endogenous MPCs after bone injury

Promoting bone healing including fracture non-unions are promising targets for bone tissue engineering due to the limited success of current clinical treatment methods. There has been significant research on the use of stem cells with and without biomaterial scaffolds to treat bone fractures due to their promising regenerative capabilities. However, the relative roles of exogenous vs. endogenous stem cells and their overall contribution to in vivo fracture repair is not well understood. The purpose of this study was to determine the interaction between exogenous and endogenous stem cells during bone healing. This study was conducted using a standardized burr-hole bone injury model in a mesenchymal progenitor cell (MPC) lineage-tracing mouse under normal homeostatic and osteoporotic conditions. Burr-hole injuries were treated with a collagen-I biomaterial loaded with and without labelled induced pluripotent stem cells (iPSCs). Using lineage-tracing, the roles of exogenous and endogenous stem cells during bone healing were examined. It was observed that treatment with iPSCs resulted in muted healing compared to untreated controls in intact mice post-injury. When the cell populations were examined histologically, iPSC-treated burr-hole defects presented with a dramatic reduction in endogenous MPCs and cell proliferation throughout the injury site. However, when the ovaries were removed and an osteoporotic-like phenotype induced in the mice, iPSCs treatment resulted in increased bone formation relative to untreated controls. In the absence of iPSCs, endogenous MPCs demonstrated robust proliferative and osteogenic capacity to undertake repair and this behaviour was disrupted in the presence of iPSCs which instead took on an osteoblast fate but with little proliferation. This study clearly demonstrates that exogenously delivered cell populations can impact the normal function of endogenous stem/progenitor populations during the normal healing cascade. These interactions need to be better understood to inform cell and biomaterial therapies to treat fractures.

Optimal concentration of mesenchymal stem cells for fracture healing in a rat model with long bone fracture

BACKGROUND

There is still no consensus on which concentration of mesenchymal stem cells (MSCs) to use for promoting fracture healing in a rat model of long bone fracture.

AIM

To assess the optimal concentration of MSCs for promoting fracture healing in a rat model.

METHODS

Wistar rats were divided into four groups according to MSC concentrations: Normal saline (C), 2.5 × 10⁶ (L), 5.0 × 10⁶ (M), and 10.0 × 10⁶ (H) groups. The MSCs were injected directly into the fracture site. The rats were sacrificed at 2 and 6 wk post-fracture. New bone formation [bone volume (BV) and percentage BV (PBV)] was evaluated using micro-computed tomography (CT). Histological analysis was performed to evaluate fracture healing score. The protein expression of factors related to MSC migration [stromal cell-derived factor 1 (SDF-1), transforming growth factor-beta 1 (TGF-β1)] and angiogenesis [vascular endothelial growth factor (VEGF)] was evaluated using western blot analysis. The expression of cytokines associated with osteogenesis [bone morphogenetic protein-2 (BMP-2), TGF-β1 and VEGF] was evaluated using real-time polymerase chain reaction.

RESULTS

Micro-CT showed that BV and PBV was significantly increased in groups M and H compared to that in group C at 6 wk post-fracture (P = 0.040, P = 0.009; P = 0.004, P = 0.001, respectively). Significantly more cartilaginous tissue and immature bone were formed in groups M and H than in group C at 2 and 6 wk post-fracture (P = 0.018, P = 0.010; P = 0.032, P = 0.050, respectively). At 2 wk post-fracture, SDF-1, TGF-β1 and VEGF expression were significantly higher in groups M and H than in group L (P = 0.031, P = 0.014; P < 0.001, P < 0.001; P = 0.025, P < 0.001, respectively). BMP-2 and VEGF expression were significantly higher in groups M and H than in group C at 6 wk post-fracture (P = 0.037, P = 0.038; P = 0.021, P = 0.010). Compared to group L, TGF-β1 expression was significantly higher in groups H (P = 0.016). There were no significant differences in expression levels of chemokines related to MSC migration, angiogenesis and cytokines associated with osteogenesis between M and H groups at 2 and 6 wk post-fracture.

CONCLUSION

The administration of at least 5.0 × 10⁶ MSCs was optimal to promote fracture healing in a rat model of long bone fractures.

Osteogenic capacity of mesenchymal stem cells from patients with osteoporotic hip fractures in vivo

PURPOSE

Human mesenchymal stem cells (MSCs) have the ability to differentiate into bone-forming osteoblasts. The aim of this study was to elucidate if MSCs from patients with OP show a senescent phenotype and explore their bone-forming ability in vivo.

MATERIALS AND METHODS

MSCs from patients with OP and controls with osteoarthritis (OA) were implanted into the subcutaneous tissue of immunodeficient mice for histological analysis and expression of human genes by RT-PCR. The expression of senescence-associated phenotype (SASP) genes, as well as p16, p21, and galactosidase, was studied in cultures of MSCs.

RESULTS

In vivo bone formation was evaluated in 103 implants (47 OP, 56 OA). New bone was observed in 45% of the implants with OP cells and 46% of those with OA cells (p = 0.99). The expression of several bone-related genes (collagen, osteocalcin, alkaline phosphatase, sialoprotein) was also similar in both groups. There were no differences between groups in SASP gene expression, p16, and p21 expression, or in senescence-associated galactosidase activity.

CONCLUSION

Senescence markers and the osteogenic capacity in vivo of MSCs from patients with OP are not inferior to that of cells from controls of similar age with OA. This supports the interest of future studies to evaluate the potential use of autologous MSCs from OP patients in bone regeneration procedures.

Multiplexed Molecular Imaging Strategy Integrated with RNA Sequencing in the Assessment of the Therapeutic Effect of Wharton's Jelly Mesenchymal Stem Cell-Derived Extracellular Vesicles for Osteoporosis

Introduction

Osteoporosis is a result of an imbalance in bone remodeling. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been considered as a potentially promising treatment for osteoporosis. However, the therapeutic effect, genetic alterations, and in vivo behavior of exogenous EVs for osteoporosis in mice models remain poorly understood.

Methods

A multiplexed molecular imaging strategy was constructed by micro-positron emission tomography (µPET)/computed tomography (CT), µCT, and optical imaging modality which reflected the osteoblastic activity, microstructure, and in vivo behavior of EVs, respectively. RNA sequencing was used to analyze the cargo of EVs, and the bone tissues of ovariectomized (OVX) mice post EV treatment.

Results

The result of [¹⁸F]NaF µPET showed an increase in osteoblastic activity in the distal femur of EV-treated mice, and the bone structural parameters derived from µCT were also improved. In terms of in vivo behavior of exogenous EVs, fluorescent dye-labeled EVs could target the distal femur of mice, whereas the uptakes of bone tissues were not significantly different between OVX mice and healthy mice. RNA sequencing demonstrated upregulation of ECM-related genes, which might associate with the PI3K/AKT signaling pathway, in line with the results of microRNA analysis showing that mir-21, mir-29, mir-221, and let-7a were enriched in Wharton’s jelly-MSC-EVs and correlated to the BMP and PI3K/AKT signaling pathways.

Conclusion

The therapeutic effect of exogenous WJ-MSC-EVs in the treatment of osteoporosis was successfully assessed by a multiplexed molecular imaging strategy. The RNA sequencing demonstrated the possible molecular targets in the regulation of bone remodeling. The results highlight the novelty of diagnostic and therapeutic strategies of EV-based treatment for osteoporosis.

Systemically impaired fracture healing in small animal research: A review of fracture repair models

Fracture healing is a complex process requiring mechanical stability, an osteoconductive matrix, and osteoinductive and osteogenic biology. This intricate process is easily disrupted by various patient factors such as chronic disease and lifestyle. As the medical complexity and age of patients with fractures continue to increase, the importance of developing relevant experimental models is becoming paramount in preclinical research. The objective of this review is to describe the most common small animal models of systemically impaired fracture healing used in the orthopedic literature including osteoporosis, diabetes mellitus, smoking, alcohol use, obesity, and ageing. This review will provide orthopedic researchers with a summary of current models of systemically impaired fracture healing used in small animals and present an overview of the methods of induction for each condition.

Short-wave enhances mesenchymal stem cell recruitment in fracture healing by increasing HIF-1 in callus

Background

As a type of high-frequency electrotherapy, a short-wave can promote the fracture healing process; yet, its underlying therapeutic mechanisms remain unclear.

Purpose

To observe the effect of Short-Wave therapy on mesenchymal stem cell (MSC) homing and relative mechanisms associated with fracture healing.

Materials and methods

For in vivo study, the effect of Short-Wave therapy to fracture healing was examined in a stabilized femur fracture model of 40 SD rats. Radiography was used to analyze the morphology and microarchitecture of the callus. Additionally, fluorescence assays were used to analyze the GFP-labeled MSC homing after treatment in 20 nude mice with a femoral fracture. For in vitro study, osteoblast from newborn rats simulated fracture site was first irradiated by the Short-Wave; siRNA targeting HIF-1 was used to investigate the role of HIF-1. Osteoblast culture medium was then collected as chemotaxis content of MSC, and the migration of MSC from rats was evaluated using wound healing assay and trans-well chamber test. The expression of HIF-1 and its related factors were quantified by q RT-PCR, ELISA, and Western blot.

Results

Our in vivo experiment indicated that Short-Wave therapy could promote MSC migration, increase local and serum HIF-1 and SDF-1 levels, induce changes in callus formation, and improve callus microarchitecture and mechanical properties, thus speeding up the healing process of the fracture site. Moreover, the in vitro results further indicated that Short-Wave therapy upregulated HIF-1 and SDF-1 expression in osteoblast and its cultured medium, as well as the expression of CXCR-4, β-catenin, F-actin, and phosphorylation levels of FAK in MSC. On the other hand, the inhibition of HIF-1α was significantly restrained by the inhibition of HIF-1α in osteoblast, and it partially inhibited the migration of MSC.

Conclusions

These results suggested that Short-Wave therapy could increase HIF-1 in callus, which is one of the crucial mechanisms of chemotaxis MSC homing in fracture healing.

Impact of Alcohol on Bone Health, Homeostasis and Fracture repair

Purpose of review

Alcohol use continues to rise globally. We review the current literature on the effect of alcohol on bone health, homeostasis and fracture repair to highlight what has been learned in people and animal models of alcohol consumption.

Recent findings

Recently, forkhead box O (FoxO) has been found to be upregulated and activated in mesenchymal stem cells (MSC) exposed to alcohol. FoxO has also been found to modulate Wnt/β-catenin signaling, which is necessary for MSC differentiation. Recent evidence suggests alcohol activates FoxO signaling, which may be dysregulating Wnt/β-catenin signaling in MSCs cultured in alcohol.

Summary

This review highlights the negative health effects learned from people and chronic and episodic binge alcohol consumption animal models. Studies using chronic alcohol exposure or alcohol exposure then bone fracture repair model have explored several different cellular and molecular signaling pathways important for bone homeostasis and fracture repair, and offer potential for future experiments to explore additional signaling pathways that may be dysregulated by alcohol exposure.

Ethanol Inhibits Mesenchymal Stem Cell Osteochondral Lineage Differentiation Due in Part to an Activation of Forkhead Box Protein O-Specific Signaling

BACKGROUND

During bone fracture repair, resident mesenchymal stem cells (MSCs) differentiate into chondrocytes, to form a cartilaginous fracture callus, and osteoblasts, to ossify the collagen matrix. Our laboratory previously reported that alcohol administration led to decreased cartilage formation within the fracture callus of rodents and this effect was mitigated by postfracture antioxidant treatment. Forkhead box protein O (FoxO) transcription factors are activated in response to intracellular reactive oxygen species (ROS), and alcohol has been shown to increase ROS. Activation of FoxOs has also been shown to inhibit canonical Wnt signaling, a necessary pathway for MSC differentiation. These findings have led to our hypothesis that alcohol exposure decreases osteochondrogenic differentiation of MSCs through the activation of FoxOs.

METHODS

Primary rat MSCs were treated with ethanol (EtOH) and assayed for FoxO expression, FoxO activation, and downstream target expression. Next, MSCs were differentiated toward osteogenic or chondrogenic lineages in the presence of 50 mM EtOH and alterations in osteochondral lineage marker expression were determined. Lastly, osteochondral differentiation experiments were repeated with FoxO1/3 knockdown or with FoxO1/3 inhibitor AS1842856 and osteochondral lineage marker expression was determined.

RESULTS

EtOH increased the expression of FoxO3a at mRNA and protein levels in primary cultured MSCs. This was accompanied by an increase in FoxO1 nuclear localization, FoxO1 activation, and downstream catalase expression. Moreover, EtOH exposure decreased expression of osteogenic and chondrogenic lineage markers. FoxO1/3 knockdown restored proosteogenic and prochondrogenic lineage marker expression in the presence of 50 mM EtOH. However, FoxO1/3 inhibitor only restored proosteogenic lineage marker expression.

CONCLUSIONS

These data show that EtOH has the ability to inhibit MSC differentiation, and this ability may rely, at least partially, on the activation of FoxO transcription factors.

Mesenchymal stem cell treatment attenuates liver and lung inflammation after ethanol intoxication and burn injury

Cutaneous burn injury is one of the most devastating injuries one can obtain, with tissue damage extending beyond the skin wound to distal organs, including the gastrointestinal tract, liver, and lungs. Multiple organ failure is a leading cause of death after burn injury, resulting in excessive systemic and localized inflammation directly contributing to end organ damage. We postulated that the gut-liver-lung inflammatory axis underscores multiple organ failure in the context of burn injury and is hyper-activated when ethanol intoxication precedes burn. Mesenchymal stem cells (MSCs) are regenerative and anti-inflammatory, and MSC treatment has been shown to be beneficial in several immune disorders and injury models. Our objective was to determine whether intravenous infusion of exogenous bone marrow-derived MSCs could reduce post-burn and intoxication pulmonary, hepatic, and systemic inflammation. Vehicle- or ethanol- (1.6 g/kg) treated mice were subjected to sham or 15% total body surface area scald burn. One hour post-injury, mice were given 5 × 10⁵ CFSE-labeled MSCs or phosphate-buffered saline intravenously (i.v.) and were euthanized 24 h later. We assessed circulating biomarkers of inflammation and liver damage, measured cytokine and chemokine production, and quantified apoptosis in lung and liver tissue. Compared to intoxicated and burned mice, those treated with MSCs had less cellularity, limited apoptosis, and a slight reduction in the pro-inflammatory cytokine interleukin-6 (IL-6) and the neutrophil chemokine, KC (CXCL1) in lung tissue. Mice with MSCs treatment had more dramatic anti-inflammatory effects on systemic and hepatic inflammation, as serum IL-6 levels were diminished by 43%, and il6 and kc expression in liver tissue were markedly reduced, as were biomarkers of liver damage, aspartate transaminase (AST) and alanine transaminase (AST), compared with intoxicated and burned mice. Taken together, our results suggest intravenous MSCs treatment can diminish systemic inflammation, lessen hepatic damage, and decrease liver and lung apoptosis and inflammation, indicating MSCs as a novel therapy for restoring homeostasis of multiple organ systems in intoxicated burn patients.

Mechanisms Underlying Normal Fracture Healing and Risk Factors for Delayed Healing

PURPOSE OF REVIEW

Substantial advances have been made in understanding the biological basis of fracture healing. Yet, it is unclear whether the presence of osteoporosis or prior or current osteoporosis therapy influences the healing process or is associated with impaired healing. This review discusses the normal process of fracture healing and the role of osteoporosis and patient-specific factors in relation to fracture repair.

RECENT FINDINGS

The definitive association of osteoporosis to impaired fracture healing remains inconclusive because of limited evidence addressing this point. eStudies testing anabolic agents in preclinical models of ovariectomized animals with induced fractures have produced mostly positive findings showing enhanced fracture repair. Prospective human clinical trials, although few in number and limited in design and to testing only one anabolic agent, have similarly yielded modestly favorable results. Interest is high for exploring currently available osteoporosis therapies for efficacy in fracture repair. Definitive data supporting their efficacy are essential in achieving approval for this indication.

Innovative Biomaterials for Bone Regrowth

The regenerative medicine, a new discipline that merges biological sciences and the fundamental of engineering to develop biological substitutes, has greatly benefited from recent advances in the material engineering and the role of stem cells in tissue regeneration. Regenerative medicine strategies, involving the combination of biomaterials/scaffolds, cells, and bioactive agents, have been of great interest especially for the repair of damaged bone and bone regrowth. In the last few years, the life expectancy of our population has progressively increased. Aging has highlighted the need for intervention on human bone with biocompatible materials that show high performance for the regeneration of the bone, efficiently and in a short time. In this review, the different aspects of tissue engineering applied to bone engineering were taken into consideration. The first part of this review introduces the bone cellular biology/molecular genetics. Data on biomaterials, stem cells, and specific growth factors for the bone regrowth are reported in this review.

Mesenchymal Stem Cell Migration during Bone Formation and Bone Diseases Therapy

During bone modeling, remodeling, and bone fracture repair, mesenchymal stem cells (MSCs) differentiate into chondrocyte or osteoblast to comply bone formation and regeneration. As multipotent stem cells, MSCs were used to treat bone diseases during the past several decades. However, most of these implications just focused on promoting MSC differentiation. Furthermore, cell migration is also a key issue for bone formation and bone diseases treatment. Abnormal MSC migration could cause different kinds of bone diseases, including osteoporosis. Additionally, for bone disease treatment, the migration of endogenous or exogenous MSCs to bone injury sites is required. Recently, researchers have paid more and more attention to two critical points. One is how to apply MSC migration to bone disease therapy. The other is how to enhance MSC migration to improve the therapeutic efficacy of bone diseases. Some considerable outcomes showed that enhancing MSC migration might be a novel trick for reversing bone loss and other bone diseases, such as osteoporosis, fracture, and osteoarthritis (OA). Although plenty of challenges need to be conquered, application of endogenous and exogenous MSC migration and developing different strategies to improve therapeutic efficacy through enhancing MSC migration to target tissue might be the trend in the future for bone disease treatment.

Effects of Episodic Alcohol Exposure on BMP2 Signaling During Tibia Fracture Healing

OBJECTIVES

To explore how alcohol affects the BMP-2 signaling pathway, which is known to play a critical role in bone and cartilage formation during fracture healing.

METHODS

A rat model was used to demonstrate the detrimental effects of alcohol exposure on tibia fracture healing. Specific components of the BMP-2 pathway were analyzed in fracture callus on days 3, 7, 14, and 21 after fracture via western immunoassays and enzyme-linked immunosorbent assay.

RESULTS

Alcohol exposure before tibia fracture demonstrated attenuation of downstream BMP-2 signaling. The BMP-2 antagonist, Chordin, may be the central component of the BMP-2-related changes demonstrated in this study. Although alcohol affected BMP-related proteins at all time points, it seems that day 14 after fracture is a critical time point for alcohol-related modulation of callus formation in our model.

CONCLUSIONS

This study may provide the scientific basis for further studies addressing whether the application of exogenous BMP-2 in patients with a history of alcohol abuse who sustain long bone fractures may or may not be of benefit.

Alcohol exposure decreases osteopontin expression during fracture healing and osteopontin-mediated mesenchymal stem cell migration in vitro

BACKGROUND

Alcohol consumption is a risk factor for impaired fracture healing, though the mechanism(s) by which this occurs are not well understood. Our laboratory has previously shown that episodic alcohol exposure of rodents negatively affects fracture callus development, callus biomechanics, and cellular signaling which regulates stem cell differentiation. Here, we examine whether alcohol alters chemokine expression and/or signaling activity in the mouse fracture callus during early fracture healing.

METHODS

A mouse model for alcohol-impaired tibia fracture healing was utilized. Early fracture callus was examined for alcohol-effects on tissue composition, expression of chemokines involved in MSC migration to the fracture site, and biomechanics. The effects of alcohol on MSC migration and cell adhesion receptors were examined in an in vitro system.

RESULTS

Mice exposed to alcohol showed decreased evidence of external callus formation, decreased callus-related osteopontin (OPN) expression levels, and decreased biomechanical stiffness. Alcohol exposure decreased rOPN-mediated MSC migration and integrin β1 receptor expression in vitro.

CONCLUSIONS

The effects of alcohol exposure demonstrated here on fracture callus-associated OPN expression, rOPN-mediated MSC migration in vitro, and MSC integrin β1 receptor expression in vitro have not been previously reported. Understanding the effects of alcohol exposure on the early stages of fracture repair may allow timely initiation of treatment to mitigate the long-term complications of delayed healing and/or fracture non-union.

Clinical and Research Approaches to Treat Non-union Fracture

PURPOSE OF REVIEW

Impaired healing outcomes or even non-unions after bone injury are still a highly relevant problem in the daily clinical life. Especially within an aging population, the occurrence of bone fractures increases and thus novel treatment approaches to overcome compromised bone regeneration are needed.

RECENT FINDINGS

The gold standard to treat delayed or non-healing bone injuries is still the use of autologous bone grafts to foster regeneration. Besides its successful treatment outcome, it also has disadvantages: a second surgery is needed in order to harvest the bone material and the material is highly limited. Looking into the recent literature, a multitude of different research approaches were already conducted to identify new possible strategies to treat impaired bone regeneration: application of mesenchymal stromal cells, platelet lysates, growth factors, interference in the immune system, or bone formation stimulation by ultrasound. This review gives an overview of the treatment approaches actually performed in the clinic as well as at the bench in the context of compromised bone healing. It clearly highlights the complexity of the nature of non-healing bone fractures as well as patient-dependent factors influencing the healing process.

The Effect of Opioids, Alcohol, and Nonsteroidal Anti-inflammatory Drugs on Fracture Union

The estimated rate of fracture nonunion is between 5% and 10%, adding significant cost to the health care system. The cause of fracture nonunion is multifactorial, including the severity of the injury, patient factors resulting in aberrancies in the biology of fracture, and the side effects of pain control modalities. Minimizing surgeon-controlled factors causing nonunion is important to reduce the cost of health care and improve patient outcomes. Opioids, alcohol, and nonsteroidal anti-inflammatory drugs have been implicated as risk factors for fracture nonunion. Current literature was reviewed to examine the effects of opioids, alcohol, and nonsteroidal anti-inflammatory drugs on fracture union.

Adenovirus-mediated bone morphogenetic protein-2 promotes osteogenic differentiation in human mesenchymal stem cells in vitro

Delayed and failed bone union following fracture is a common clinical complication that requires treatment in orthopedics. Cell-based therapies and tissue-engineering approaches are potential therapeutic strategies for bone repair and fracture healing. However, the effect of adenovirus expressing bone morphogenetic protein-2 (Ad-BMP-2) on the osteogenic ability of human mesenchymal stem cells (hMSCs) has remained to be fully elucidated. Therefore, in the present study, hMSCs were transduced using Ad-BMP-2 to assess the effects of its application and to determine whether Ad-BMP-2 promotes the osteogenic differentiation of hMSCs. The purity of the hMSC cultures was assessed using flow cytometric analysis. In order to assess the osteogenic activity, alkaline phosphatase activity (ALP) was measured and to estimate the osteoblastic mineralization and calcification, von Kossa staining for phosphates was performed. Cells positive for Src homology 2 domain were determined to be hMSCs and the presence of CD34 was used to distinguish hematopoietic lineages. Following treatment, the Ad-BMP-2 and control group had significantly increased ALP levels (P<0.05). Compared to the blank group and the group transfected with adenoviral vector containing LacZ, the phosphate deposition in the Ad-BMP-2 group and the positive control group treated with dexamethasone was markedly increased. The results of the present study suggested that Ad-BMP-2 promotes osteogenic differentiation in hMSCs and may have a potential application in treating delayed union and nonunion following bone fracture.

Adiponectin regulates BMSC osteogenic differentiation and osteogenesis through the Wnt/β-catenin pathway

Recent studies have demonstrated the stimulatory effects of adiponectin on bone formation, but the mechanism underlying these effects remains unclear. The Wnt/β-catenin pathway, one of the most important pathways in osteogenesis, has rarely been associated with the osteogenic effects of adiponectin in previous studies. The present study was designed to investigate the effects of adiponectin on bone mesenchymal stem cell (BMSC) osteogenic differentiation and bone formation through the Wnt/β-catenin pathway. We detected adiponectin receptor expression in BMSCs, constructed a recombinant adenovirus containing the human adiponectin gene, and then used the adenovirus to transfect BMSCs in vitro or injected the adenovirus into bone defect areas in animal models. Wnt/β-catenin pathway and osteogenesis were detected by real-time PCR, western blotting, immunofluorescence, HE staining and micro-CT. In both our in vivo and in vitro experiments, we detected higher gene and protein expression levels of the Wnt/β-catenin pathway-related factors β-catenin and cyclinD1 in adiponectin transgenic BMSCs and rats. Similar results were noted regarding the gene and protein expression levels of osteogenesis-related genes. In addition, more new bone formation was observed in the adiponectin-treated groups. Our results indicate that adiponectin could facilitate BMSC osteogenic differentiation and osteogenesis, and the Wnt/β-catenin pathway was involved in the osteogenic effect of adiponectin.

Lipopolysaccharide-induced memory impairment in rats: a model of Alzheimer's disease

Alzheimer's disease (AD) is a primary cause of dementia in the middle-aged and elderly worldwide. Animal models for AD are widely used to study the disease mechanisms as well as to test potential therapeutic agents for disease modification. Among the non-genetically manipulated neuroinflammation models for AD, lipopolysaccharide (LPS)-induced animal model is commonly used. This review paper aims to discuss the possible factors that influence rats' response following LPS injection. Factors such as dose of LPS, route of administration, nature and duration of exposure as well as age and gender of animal used should be taken into account when designing a study using LPS-induced memory impairment as model for AD.

Immunomodulatory oligonucleotide IMT504: Effects on mesenchymal stem cells as a first-in-class immunoprotective/immunoregenerative therapy

The immune responses of humans and animals to insults (i.e., infections, traumas, tumoral transformation and radiation) are based on an intricate network of cells and chemical messengers. Abnormally high inflammation immediately after insult or abnormally prolonged pro-inflammatory stimuli bringing about chronic inflammation can lead to life-threatening or severely debilitating diseases. Mesenchymal stem cell (MSC) transplant has proved to be an effective therapy in preclinical studies which evaluated a vast diversity of inflammatory conditions. MSCs lead to resolution of inflammation, preparation for regeneration and actual regeneration, and then ultimate return to normal baseline or homeostasis. However, in clinical trials of transplanted MSCs, the expectations of great medical benefit have not yet been fulfilled. As a practical alternative to MSC transplant, a synthetic drug with the capacity to boost endogenous MSC expansion and/or activation may also be effective. Regarding this, IMT504, the prototype of a major class of immunomodulatory oligonucleotides, induces in vivo expansion of MSCs, resulting in a marked improvement in preclinical models of neuropathic pain, osteoporosis, diabetes and sepsis. IMT504 is easily manufactured and has an excellent preclinical safety record. In the small number of patients studied thus far, IMT504 has been well-tolerated, even at very high dosage. Further clinical investigation is necessary to demonstrate the utility of IMT504 for resolution of inflammation and regeneration in a broad array of human diseases that would likely benefit from an immunoprotective/immunoregenerative therapy.

Percutaneous Autologous Bone Marrow-Derived Mesenchymal Stromal Cell Implantation Is Safe for Reconstruction of Human Lower Limb Long Bone Atrophic Nonunion

Objective

Nonunion is defined as a minimum of a 9-month period of time since an injury with no visibly progressive signs of healing for 3 months. Recent studies show that application of mesenchymal stromal cells (MSCs) in the laboratory setting is effective for bone regeneration. Animal studies have shown that MSCs can be used to treat nonunions. For the first time in an Iranian population, the present study investigated the safety of MSC implantation to treat human lower limb long bone nonunion.

Materials and Methods

It is a prospective clinical trial for evaluating the safety of using autologus bone marrow derived mesenchymal stromal cells for treating nonunion. Orthopedic surgeons evaluated 12 patients with lower limb long bone nonunion for participation in this study. From these, 5 complied with the eligibility criteria and received MSCs. Under fluoroscopic guidance, patients received a one-time implantation of 20-50×106 MSCs into the nonunion site. All patients were followed by anterior-posterior and lateral X-rays from the affected limb, in addition to hematological, biochemical, and serological laboratory tests obtained before and 1, 3, 6, and 12 months after the implantation. Possible adverse effects that included local or systemic, serious or non-serious, and related or unrelated effects were recorded during this time period.

Results

From a safety perspective, all patients tolerated the MSCs implantation during the 12 months of the trial. Three patients had evidence of bony union based on the after implantation Xrays.

Conclusion

The results have suggested that implantation of bone marrow-derived MSCs is a safe treatment for nonunion. A double-blind, controlled clinical trial is required to assess the efficacy of this treatment (Registration Number: NCT01206179).

Mesenchymal Stromal Cells Implantation in Combination with Platelet Lysate Product Is Safe for Reconstruction of Human Long Bone Nonunion

Objective

Nonunion is defined as a minimum of 9 months since injury without any visible progressive signs of healing for 3 months. Recent literature has shown that the application of mesenchymal stromal cells is safe, in vitro and in vivo, for treating long bone nonunion. The present study was performed to investigate the safety of mesenchymal stromal cell (MSC) implantation in combination with platelet lysate (PL) product for treating human long bone nonunion.

Materials and Methods

In this case series clinical trial, orthopedic surgeons visited eighteen patients with long bone nonunion, of whom 7 complied with the eligibility criteria. These patients received mesenchymal stromal cells (20 million cells implanted once into the nonunion site using a fluoroscopic guide) in combination with PL product. For evaluation of the effects of this intervention all the patients were followed up by taking anterior-posterior and lateral X-rays of the affected limb before and 1, 3, 6, and 12 months after the implantation. All side effects (local or systemic, serious or non-serious, related or unrelated) were observed during this time period.

Results

From a safety perspective the MSC implantation in combination with PL was very well tolerated during the 12 months of the trial. Four patients were healed; based on the control Xray evidence, bony union had occurred.

Conclusion

Results from the present study suggest that the implantation of bone marrow-derived MSCs in combination with PL is safe for the treatment of nonunion. A double blind, controlled clinical trial is required to assess the efficacy of this treatment (Registration Number: NCT01206179).

Effects of simvastatin on the osteogenic differentiation and immunomodulation of bone marrow mesenchymal stem cells

The present study aimed to investigate the effects of simvastatin on the bone differentiation capacity and immunological characteristics of bone marrow mesenchymal stem cells (BMSCs). BMSCs were isolated and cultured in medium containing 1.0 µmol/ml simvastatin. The alkaline phosphatase activity, mRNA expression levels of osteocalcin and bone sialoprotein, and calcium nodule formation were assessed to determine the osteogenic differentiation capability of BMSCs. To investigate alterations in the immunological properties of simvastation‑treated BMSCs, the immunogenicity of these cells and the effect of BMSCs on phytohemagglutinin‑stimulated lymphocyte proliferation were also assessed. Following treatment with simvastatin, the alkaline phosphatase activity, and mRNA expression levels of osteocalcin and bone sialoprotein were increased significantly in the BMSCs. In addition, von Kossa staining revealed a brown calcium‑positive reaction zone in simvastatin‑treated cells. Simvastatin‑induced BMSCs revealed no affect on the proliferation of allogeneic lymphocytes, however, inhibited phytohemagglutinin‑induced lymphocyte proliferation. Collectively, simvastatin promoted the osteogenic differentiation of BMSCs significantly without affecting their immunosuppressive properties.

Alcohol inhibits osteopontin-dependent transforming growth factor-β1 expression in human mesenchymal stem cells

Alcohol (EtOH) intoxication is a risk factor for increased morbidity and mortality with traumatic injuries, in part through inhibition of bone fracture healing. Animal models have shown that EtOH decreases fracture callus volume, diameter, and biomechanical strength. Transforming growth factor β1 (TGF-β1) and osteopontin (OPN) play important roles in bone remodeling and fracture healing. Mesenchymal stem cells (MSC) reside in bone and are recruited to fracture sites for the healing process. Resident MSC are critical for fracture healing and function as a source of TGF-β1 induced by local OPN, which acts through the transcription factor myeloid zinc finger 1 (MZF1). The molecular mechanisms responsible for the effect of EtOH on fracture healing are still incompletely understood, and this study investigated the role of EtOH in affecting OPN-dependent TGF-β1 expression in MSC. We have demonstrated that EtOH inhibits OPN-induced TGF-β1 protein expression, decreases MZF1-dependent TGF-β1 transcription and MZF1 transcription, and blocks OPN-induced MZF1 phosphorylation. We also found that PKA signaling enhances OPN-induced TGF-β1 expression. Last, we showed that EtOH exposure reduces the TGF-β1 protein levels in mouse fracture callus. We conclude that EtOH acts in a novel mechanism by interfering directly with the OPN-MZF1-TGF-β1 signaling pathway in MSC.

Bone marrow derived stem cells in joint and bone diseases: a concise review

Stem cells have huge applications in the field of tissue engineering and regenerative medicine. Their use is currently not restricted to the life-threatening diseases but also extended to disorders involving the structural tissues, which may not jeopardize the patients' life, but certainly influence their quality of life. In fact, a particularly popular line of research is represented by the regeneration of bone and cartilage tissues to treat various orthopaedic disorders. Most of these pioneering research lines that aim to create new treatments for diseases that currently have limited therapies are still in the bench of the researchers. However, in recent years, several clinical trials have been started with satisfactory and encouraging results. This article aims to review the concept of stem cells and their characterization in terms of site of residence, differentiation potential and therapeutic prospective. In fact, while only the bone marrow was initially considered as a "reservoir" of this cell population, later, adipose tissue and muscle tissue have provided a considerable amount of cells available for multiple differentiation. In reality, recently, the so-called "stem cell niche" was identified as the perivascular space, recognizing these cells as almost ubiquitous. In the field of bone and joint diseases, their potential to differentiate into multiple cell lines makes their application ideally immediate through three main modalities: (1) cells selected by withdrawal from bone marrow, subsequent culture in the laboratory, and ultimately transplant at the site of injury; (2) bone marrow aspirate, concentrated and directly implanted into the injury site; (3) systemic mobilization of stem cells and other bone marrow precursors by the use of growth factors. The use of this cell population in joint and bone disease will be addressed and discussed, analysing both the clinical outcomes but also the basic research background, which has justified their use for the treatment of bone, cartilage and meniscus tissues.

Mesenchymal stem cells in the treatment of pediatric diseases

BACKGROUND

In recent years, the incredible interests in mesenchymal stem cells have boosted the expectations of both patients and physicians. Unlike embryonic stem cells, neither their procurement nor their use is deemed controversial. Moreover, their immunomodulatory capacity coupled with low immunogenicity has opened up their allogenic use, consequently broadening the possibilities for their application. In May 2012, Canadian health regulators approved Prochymal, the first mesenchymal stem cells-based drug, for acute graft-versus-host diseases in children who have failed to respond to steroid treatment. The aim of this article is to review the recent advances in mesenchymal stem cells for pediatric diseases.

DATA SOURCES

A literature review was performed on PubMed from 1966 to 2013 using the MeSH terms "mesenchymal stem cells", "clinical trials" and "children". Additional articles were identified by a hand search of the references list in the initial search.

RESULTS

The following categories are described: general properties, mechanisms of action, graft-versus-host diseases, cardiovascular diseases, liver diseases, inflammatory bowel diseases, osteoarticular diseases, autoimmune diseases, type 1 diabetes, and lung diseases.

CONCLUSIONS

Mesenchymal stem cells, owing to their availability, immunomodulatory properties, low immunogenicity, and therapeutic potential, have become one of the most attractive options for the treatment of a wide range of diseases. It is expected to see more and more clinical trials and applications of mesenchymal stem cells for pediatric diseases in the near future.

From ‘Blade Runner’ to ‘Stem-Cell Player’ and beyond

Modern athletes are constantly susceptible to performance-threatening injury as they push their bodies to greater limits and endure higher physical stresses. Loss of performance and training time can adversely and permanently affect a sportsperson’s career. Now more than ever with advancing medical technology the answer may lie in biologic therapy. We have been using peripheral blood stem cells (PBSC) clinically and have been able to demonstrate that stem cells differentiate into target cells to enable regenerative repair. The potential of this technique as a regenerative agent can be seen in three broad applications: 1) articular cartilage, 2) bone and 3) soft tissue. This article highlights the successful cases, among many, in all three of these applications.