Osteogenic gene expression decreases in stromal cells of patients with osteonecrosis

Bone Marrow Multipotent Mesenchymal Stromal Cells as Autologous Therapy for Osteonecrosis: Effects of Age and Underlying Causes

Bone marrow (BM) is a reliable source of multipotent mesenchymal stromal cells (MSCs), which have been successfully used for treating osteonecrosis. Considering the functional advantages of BM-MSCs as bone and cartilage reparatory cells and supporting angiogenesis, several donor-related factors are also essential to consider when autologous BM-MSCs are used for such regenerative therapies. Aging is one of several factors contributing to the donor-related variability and found to be associated with a reduction of BM-MSC numbers. However, even within the same age group, other factors affecting MSC quantity and function remain incompletely understood. For patients with osteonecrosis, several underlying factors have been linked to the decrease of the proliferation of BM-MSCs as well as the impairment of their differentiation, migration, angiogenesis-support and immunoregulatory functions. This review discusses the quality and quantity of BM-MSCs in relation to the etiological conditions of osteonecrosis such as sickle cell disease, Gaucher disease, alcohol, corticosteroids, Systemic Lupus Erythematosus, diabetes, chronic renal disease and chemotherapy. A clear understanding of the regenerative potential of BM-MSCs is essential to optimize the cellular therapy of osteonecrosis and other bone damage conditions.

An Intermediate Concentration of Calcium with Antioxidant Supplement in Culture Medium Enhances Proliferation and Decreases the Aging of Bone Marrow Mesenchymal Stem Cells

Human bone marrow stem cells (HBMSCs) are isolated from the bone marrow. Stem cells can self-renew and differentiate into various types of cells. They are able to regenerate kinds of tissue that are potentially used for tissue engineering. To maintain and expand these cells under culture conditions is difficult—they are easily triggered for differentiation or death. In this study, we describe a new culture formula to culture isolated HBMSCs. This new formula was modified from NCDB 153, a medium with low calcium, supplied with 5% FBS, extra growth factor added to it, and supplemented with N-acetyl-L-cysteine and L-ascorbic acid-2-phosphate to maintain the cells in a steady stage. The cells retain these characteristics as primarily isolated HBMSCs. Moreover, our new formula keeps HBMSCs with high proliferation rate and multiple linage differentiation ability, such as osteoblastogenesis, chondrogenesis, and adipogenesis. It also retains HBMSCs with stable chromosome, DNA, telomere length, and telomerase activity, even after long-term culture. Senescence can be minimized under this new formulation and carcinogenesis of stem cells can also be prevented. These modifications greatly enhance the survival rate, growth rate, and basal characteristics of isolated HBMSCs, which will be very helpful in stem cell research.

(-)-Epigallocatechin-3-Gallate (EGCG) Enhances Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Osteoporosis is the second most-prevalent epidemiologic disease in the aging population worldwide. Cross-sectional and retrospective evidence indicates that tea consumption can mitigate bone loss and reduce risk of osteoporotic fractures. Tea polyphenols enhance osteoblastogenesis and suppress osteoclastogenesis in vitro. Previously, we showed that (-)-epigallocatechin-3-gallate (EGCG), one of the green tea polyphenols, increased osteogenic differentiation of murine bone marrow mesenchymal stem cells (BMSCs) by increasing the mRNA expression of osteogenesis-related genes, alkaline phosphatase activity and, eventually, mineralization. We also found that EGCG could mitigate bone loss and improve bone microarchitecture in ovariectomy-induced osteopenic rats, as well as enhancing bone defect healing partially via bone morphogenetic protein 2 (BMP2). The present study investigated the effects of EGCG in human BMSCs. We found that EGCG, at concentrations of both 1 and 10 µmol/L, can increase mRNA expression of BMP2, Runx2, alkaline phosphatase (ALP), osteonectin and osteocalcin 48 h after treatment. EGCG increased ALP activity both 7 and 14 days after treatment. Furthermore, EGCG can also enhance mineralization two weeks after treatment. EGCG without antioxidants also can enhance mineralization. In conclusion, EGCG can increase mRNA expression of BMP2 and subsequent osteogenic-related genes including Runx2, ALP, osteonectin and osteocalcin. EGCG further increased ALP activity and mineralization. Loss of antioxidant activity can still enhance mineralization of human BMSCs (hBMSCs).

Imbalanced bone turnover markers and low bone mineral density in patients with osteonecrosis of the femoral head

PURPOSE

There have been few studies investigating the cumulative effect of individual factors related to bone metabolism on the systemic balance between bone formation and resorption in patients with osteonecrosis of the femoral head (ONFH). We investigated bone mineral density (BMD) of lumbar spine and bone turnover markers that reflect systemic bone metabolism.

METHODS

Two-hundred twenty patients with ONFH were matched to 220 healthy subjects according to age, gender, and body mass index. ONFH patients were divided into steroid-induced (18%), alcoholic (21%), and idiopathic ONFH (61%) and subgroup analysis was performed to exclude the effect of steroid and malnutrition on bone metabolism. We compared lumbar spine bone mineral density (BMD) between groups and measured serum bone-specific alkaline phosphatase (BALP) and urinary deoxypyridinoline/creatinine (Dpd/Cr) ratio.

RESULTS

Logistic regression analysis revealed low spine BMD was significantly associated with each subgroup of ONFH when compared with that of the control group (odds ratio of 2.27, 4.24, and 1.86 in alcoholic, steroid, and idiopathic ONFH, respectively). The mean value of serum BALP (27.02 U/L) was within the normal reference range while average urine Dpd/Cr ratio (6.24 nM/mM) increased in ONFH group when compared with respective reference range.

CONCLUSION

Spine BMD decreased and urinary Dpd/Cr ratio increased in patients with non-traumatic ONFH. Further studies will be necessary to identify whether non-traumatic ONFH is merely a regional disease confined to the femoral head or may affect systemic bone metabolism.

MicroRNA-23a-3p inhibitor decreases osteonecrosis incidence in a rat model

The mechanism of steroid-associated femoral head necrosis remains unclear. The present study investigated the role of microRNA-23a-3p (miR-23a-3p) in the incidence of osteonecrosis in a rat model. An miR-23a-3p mimic, an inhibitor and a negative control were transfected into bone mesenchymal stem cells using a lentiviral vector, and then injected into the steroid-induced femoral head necrosis model. Osteonecrosis incidence was assessed by micro computed tomography and histopathology. Low-density lipoprotein receptor-related protein 5 (LRP-5) expression was assessed by immunohistochemistry. The results demonstrated the incidence of osteonecrosis decreased in the miR-23a-3p inhibitor group compared with the miR-23a-3p mimic group (18.2% vs. 75%; P<0.05). The ratio of bone volume/total volume and trabecular thickness were significantly increased in the miR-23a-3p inhibitor group compared with the miR-23a mimic group. The expression level of LRP-5 was higher in the miR-23a-3p inhibitor group. The present study indicated that miR may provide a novel and alternative approach for understanding the mechanism underlying steroid-associated necrosis of the femoral head.

Feasibility and Efficacy of Autologous Bone Marrow Aspirate Transplantation Combined with Human Parathyroid Hormone 1-34 Administration to Treat Osteonecrosis in a Rabbit Model

No studies have examined the transplantation of a bone marrow aspirate (BMA) containing mesenchymal stem cells (MSCs) combined with human parathyroid hormone 1-34 (hPTH1-34) administration. Therefore, we evaluated the feasibility and efficacy of autologous BMA transplantation combined with hPHT1-34 administration in a bone necrosis model. The metatarsal bones of rabbits were necrotized using liquid nitrogen, and the rabbits received a BMA transplantation or saline injection followed by hPTH1-34 (30 μg/kg) or saline administration three times per week (n = 3-4 per group). The rabbits were euthanized at 12 weeks after the initiation of treatment. No systemic adverse effects or local neoplastic lesions were observed. Importantly, the rabbits in the BMA transplantation plus hPTH1-34 group showed the highest bone volumes and histological scores of new bone. These data confirmed the feasibility of BMA transplantation combined with hPTH1-34, at least during the experimental period. The observed efficacy may be explained by a synergistic effect from the stimulation of MSC differentiation to osteoblasts with hPTH1-34-mediated suppression of apoptosis in osteoblasts. These results indicate the promising potential for BMA transplantation combined with hPTH1-34 administration in bone necrosis treatment. Longer term experiments are needed to confirm the safety of this therapeutic strategy.

High-Dose Corticosteroid Use and Risk of Hip Osteonecrosis: Meta-Analysis and Systematic Literature Review

The effect of varying corticosteroid regimens on hip osteonecrosis incidence remains unclear. We performed a meta-analysis and systematic literature review to determine osteonecrosis occurrences in patients taking corticosteroids at varying mean and cumulative doses and treatment durations, and whether medical diagnoses affected osteonecrosis incidence. Fifty-seven studies (23,561 patients) were reviewed. Regression analysis determined significance between corticosteroid usage and osteonecrosis incidence. Osteonecrosis incidence was 6.7% with corticosteroid treatment of >2 g (prednisone-equivalent). Systemic lupus erythematosus patients had positive correlations between dose and osteonecrosis incidence. Each 10 mg/d increase was associated with a 3.6% increase in osteonecrosis rate, and >20 mg/d resulted in a higher osteonecrosis incidence. Clinicians must be wary of osteonecrosis in patients on high corticosteroid regimens, particularly in systematic lupus erythematosus.

Elevated level of membrane microparticles in the disease of steroid-induced vascular osteonecrosis

As a common disease, osteonecrosis attracts more and more attention. In this paper, we investigated the relationship between the alterations of endothelial-derived and platelet-derived microparticles and the changes of coagulation and inflammation in the steroid-induced avascular osteonecrosis of femoral head using the rabbit model. We also explored the possible mechanism of the membrane particles associated with the development of the rabbit femoral head ischemic necrosis. With a 28-day continuous observation, the level of membrane microparticles was significantly heightened after methylprednisolone treatment. The coagulating and inflammatory factors also tended to increase. The data demonstrated that the levels of membrane microparticles had significantly individual differences, which meant the increased levels of membrane microparticles may be related to hypercoagulability, thrombosis, and inflammation in microcirculation and played an important role in steroid-induced osteonecrosis. It will be very useful and helpful to guide clinical trials.

Systemic application of teriparatide for steroid induced osteonecrosis in a rat model

Background

Steroid associated osteonecrosis is difficult to treat. Teriparatide, as the only one bone anabolic drug, has achieved very promising effect in osteoporosis and other bone skeletal diseases. We carried out this animal study to evaluate the effect of subcutaneous injection of teriparatide for the steroid induced femoral head necrosis in a rat model.

Methods

24 Sprague–Dawley male adult rats were included in the study. All the rats were randomized into 4 groups: 18 rats from LPS/MPS group, LPS/MPS + PTH group and LPS/MPS + NS group were given lipopolysaccharide (20 μg/kg) and methylprednisolone (40 mg/kg) to establish the steroid induced osteonecrosis model. 6 rats from NS group only received normal saline. 4 weeks later, All the rats in LPS/MPS group and NS group were sacrificed and the femoral heads were harvested. After that, the 6 rats in the LPS/MPS + PTH group received subcutaneous injection of 20 μg/kg teriparatide and LPS/MPS + NS group only received equal amount of normal saline. After 4 weeks, the serum bone marker was tested and the femoral head were harvested. Micro-CT and histological examination were performed to compare the incidence of osteonecrosis and trabeculae parameters for the femoral head.

Results

At 4 weeks, rats in LPS/MPS group showed significant osteonecrosis by histological examination (83.3 %) which suggested successful steroid induced osteronecrosis animal models were established. After the treatment of 4 weeks, the LPS/MPS + PTH group showed significant lower incidence rate of osteonecrosis compared with the LPS/MPS + NS group (16.7 % vs.75 %, P < 0.05). The micro CT examination showed higher bone volume/total volume, trabecula thickness and bone mineral density in the LPS/MPS + PTH group compared with the LPS/MPS + NS group. The serum osteocalcin was a little higher in the LPS/MPS + PTH group (4.54 ± 1.61vs.3.58 ± 1.81, P = 0.358), but it didn’t reach a statistical significance.

Conclusions

Systemic application of teriparatide for steroid induced osteonecrosis in rats showed a beneficial effect. This may be one promising therapy for early stage osteonecrosis.

Phytomolecule icaritin incorporated PLGA/TCP scaffold for steroid-associated osteonecrosis: Proof-of-concept for prevention of hip joint collapse in bipedal emus and mechanistic study in quadrupedal rabbits

Steroid-associated osteonecrosis (SAON) may lead to joint collapse and subsequent joint replacement. Poly lactic-co-glycolic acid/tricalcium phosphate (P/T) scaffold providing sustained release of icaritin (a metabolite of Epimedium-derived flavonoids) was investigated as a bone defect filler after surgical core-decompression (CD) to prevent femoral head collapse in a bipedal SAON animal model using emu (a large flightless bird). The underlying mechanism on SAON was evaluated using a well-established quadrupedal rabbit model. Fifteen emus were established with SAON, and CD was performed along the femoral neck for the efficacy study. In this CD bone defect, a P/T scaffold with icaritin (P/T/I group) or without icaritin (P/T group) was implanted while no scaffold implantation was used as a control. For the mechanistic study in rabbits, the effects of icaritin and composite scaffolds on bone mesenchymal stem cells (BMSCs) recruitment, osteogenesis, and anti-adipogenesis were evaluated. Our efficacy study showed that P/T/I group had the significantly lowest incidence of femoral head collapse, better preserved cartilage and mechanical properties supported by more new bone formation within the bone tunnel. For the mechanistic study, our in vitro tests suggested that icaritin enhanced the expression of osteogenesis related genes COL1α, osteocalcin, RUNX2, and BMP-2 while inhibited adipogenesis related genes C/EBP-ß, PPAR-γ, and aP2 of rabbit BMSCs. Both P/T and P/T/I scaffolds were demonstrated to recruit BMSCs both in vitro and in vivo but a higher expression of migration related gene VCAM1 was only found in P/T/I group in vitro. In conclusion, both efficacy and mechanistic studies show the potential of a bioactive composite porous P/T scaffold incorporating icaritin to enhance bone defect repair after surgical CD and prevent femoral head collapse in a bipedal SAON emu model.

Osteonecrosis repair with bone marrow cell therapies: state of the clinical art

INTRODUCTION

Hip osteonecrosis is a pathological condition resulting from cellular impairment due to reduction in osteoblast activity and local mesenchymal stem cell populations. Cell-based therapies might aid in overcoming these deficiencies by providing stem cells and other progenitor cells to potentially improve the local cellular environment in the affected hip.

METHODS

A PubMed search, using the search terms "hip osteonecrosis" and "mesenchymal stem cells", was conducted in December 2013. A total of 15 publications were identified and reviewed for clinical outcomes.

FINDINGS

Clinical studies of patients with osteonecrosis treated with mesenchymal stem cells showed beneficial effects. No unexpected adverse events were identified in these studies. Core decompression was the usual method for autologous bone marrow cell implantation into the femoral head. However, other methods have been used such as arterial or venous delivery. A rationale for the use of cytotherapy, as well as the different descriptions of the techniques of implantation MSCs (autologous vs. allogenic, concentration vs. expansion), is provided in the context of treating hip osteonecrosis. Current problems and future challenges with cytotherapy and associated techniques are discussed. This article is part of a Special Issue entitled "Stem Cells and Bones".

Bone turnover markers failed to predict the occurrence of osteonecrosis of the femoral head: a preliminary study

BACKGROUND

The early detection of osteonecrosis of the femoral head (ONFH) is difficult, but important for prevention of destruction of the femoral head. The objective of this study was to determine whether the occurrence of osteonecrosis of the femoral head (ONFH) correlates with changes in bone turnover markers.

METHODS

In 40 patients undergoing primary total hip arthroplasty (THA), different bone turnover markers and hormones (bone specific alkaline phosphatase, osteocalcin, beta cross-laps, 25-hydroxy-cholecalciferol, and parathormone) gained from blood were determined on the morning of the surgery. Twenty-two patients needed a THA due to progressed ONFH. In 18 cases blood was gained from patients with the indication for a THA given due to advanced osteoarthritis (AO) of the hip.

RESULTS

Bone specific alkaline phosphatase, osteocalcin, beta cross-laps, and parathormone did not show any deviation from standard values, neither for the group of osteonecrosis nor for the osteoarthritis group. 25-Hydroxy-cholecalciferol revealed on average decreased values without significant differences between both groups (P < 0.05). The tested bone turnover markers and hormones failed to predict the occurrence of ONFH. Thus, the focus has to be put on different parameters to find a specific parameter that possibly predicts the risk of ostenecrosis and that is suited to follow up ONFH.

Alendronate in the prevention of collapse of the femoral head in nontraumatic osteonecrosis: a two-year multicenter, prospective, randomized, double-blind, placebo-controlled study

OBJECTIVE

Osteonecrosis is one of the major debilitating skeletal disorders. Most patients with osteonecrosis of the femoral head eventually need surgery, usually total hip arthroplasty (THA), within a few years of onset. Previous studies showed that alendronate has a pharmacologic effect in reducing osteoclast activity and that it significantly reduced the incidence of collapse of the femoral head in the osteonecrotic hip. The purpose of this study was to determine the cumulative incidence of THA in patients with osteonecrosis of the femoral head and the time-to-event after treatment with alendronate versus placebo during the study period.

METHODS

A 2-year multicenter, prospective, randomized, double-blind study was performed. From June 2005 to December 2006, 64 patients were enrolled and randomly assigned to the alendronate or placebo group. In patients with bilateral hip osteonecrosis who met the inclusion criteria, both hips were counted in the analyses. Five patients were excluded from the analysis because they did not comply with any of the study regimens. Seven patients were ineligible because they were not diagnosed as having stage IIC or stage IIIC disease according to the University of Pennsylvania system. Thus, a total of 52 patients (65 hips) were assessed in this study. Disease progression was evaluated by radiography and magnetic resonance imaging (MRI). The Harris Hip Score and the Short Form 36 health survey were used to rate hip function and quality of life, respectively.

RESULTS

There was no significant difference in radiographic and MRI data between the 2 study groups. Four of 32 hips in the alendronate treatment group underwent THA, while 5 of 33 hips in the placebo group had THA (P = 0.837). No differences were noted in disease progression, Harris Hip Scores, or Short Form 36 scores between the 2 groups.

CONCLUSION

Alendronate has no obvious effect on preventing the necessity for THA, reducing disease progression, or improving life quality.

Proliferation and differentiation potential of human adipose-derived mesenchymal stem cells isolated from elderly patients with osteoporotic fractures

Aging has less effect on adipose-derived mesenchymal stem cells (ADSCs) than on bone marrow-derived mesenchymal stem cells (BMSCs), but whether the fact holds true in stem cells from elderly patients with osteoporotic fractures is unknown. In this study, ADSCs and BMSCs of the same donor were harvested and divided into two age groups. Group A consisted of 14 young patients (36.4 ± 11.8 years old), and group B consisted of eight elderly patients (71.4 ± 3.6 years old) with osteoporotic fractures. We found that the doubling time of ADSCs from both age groups was maintained below 70 hrs, while that of BMSCs increased significantly with the number of passage. When ADSCs and BMSCs from the same patient were compared, there was a significant increase in the doubling time of BMSCs in each individual from passages 3 to 6. On osteogenic induction, the level of matrix mineralization of ADSCs from group B was comparable to that of ADSCs from group A, whereas BMSCs from group B produced least amount of mineral deposits and had a lower expression level of osteogenic genes. The p21 gene expression and senescence-associated β-galactosidase activity were lower in ADSCs compared to BMSCs, which may be partly responsible for the greater proliferation and differentiation potential of ADSCs. It is concluded that the proliferation and osteogenic differentiation of ADSCs were less affected by age and multiple passage than BMSCs, suggesting that ADSCs may become a potentially effective therapeutic option for cell-based therapy, especially in elderly patients with osteoporosis.

Dexamethasone has variable effects on mesenchymal stromal cells

BACKGROUND AIMS

Dexamethasone (Dex) is a potent synthetic member of the glucocorticoid class of steroid drugs. Frequently, Dex has been used to enhance osteogenic, chondrogenic and adipogenic differentiation of mesenchymal stromal cells (MSC). Recently, Dex was applied to promote MSC proliferation, because of the rare frequency of MSC in bone marrow, and could protect the cells from apoptosis. The effects of Dex on MSC cytobiology behavior needs to be investigated.

METHODS

MSC were obtained from human umbilical cord. The surface phenotype and functional characterization of MSC cultured with different concentrations of Dex were investigated, in comparison with a control group, including MSC proliferation, apoptosis, cytokine expression and immunosuppression.

RESULTS

Different concentrations of Dex exerted diverse effects on MSC proliferation and apoptosis. Dex was also able to affect the pattern of cytokine expression of MSC. Furthermore, Dex impaired immunosuppression of MSC on peripheral blood mononuclear cells.

CONCLUSIONS

A low dose of Dex favors MSC expansion in vitro, and protects against apoptosis. It is not suitable for MSC to be pre-treated with Dex when they are to be used to treat immunologic disease. However, when MSC are applied to promote angiogenesis, it is beneficial for them to be pre-treated with 10(-9) mol/L Dex.

Cytotherapy of osteonecrosis of the femoral head: a mini review

The pathogenesis and aetiology of nontraumatic osteonecrosis of the femoral head has not been revealed completely. However, with advances in stem cell research and regenerative medicine, it is believed that the onset of osteonecrosis of the femoral head probably has a cellular origin, and the possible therapy of osteonecrosis of the femoral head based on cytotherapy has great potential. In this review, the aetiology of osteonecrosis of the femoral head, animal experiments and clinical applications of cytotherapy are summarized and analysed. Current problems and future challenges are discussed.

Different differentiation of stroma cells from patients with osteonecrosis: a pilot study

Osteonecrosis (ON) is commonly caused by high doses of glucocorticoids or ethanol intake. We previously reported suppression of BMP-2 by dexamethasone was more pronounced and enhancement by lovastatin was less pronounced in bone marrow stromal cells (BMSCs) from patients with ON than from patients without ON. We therefore presumed the BMSCs might be dysfunctional in patients with ON and performed this pilot study. We obtained BMSCs from 10 patients with ethanol-induced ON, 10 patients with glucocorticoid-induced ON, and 12 patients without ON as control subjects, checking third passage cells for osteogenic and adipogenic gene expression and differentiation ability. BMSCs from patients with glucocorticoid-induced ON possessed less osteogenic gene expression and less osteogenic differentiation, whereas BMSCs from patients with ethanol-induced ON possessed more adipogenic gene expression and more adipogenic differentiation. Dysfunction of BMSCs may be one of the causes of ON, with differing dysfunction in ethanol-induced ON and glucocorticoid-induced ON. Glucocorticoids may possess more of a suppressive effect on osteogenesis than ethanol, whereas ethanol may possess a more potent adipogenic effect than glucocorticoids on BMSCs.

Glucocorticoids in osteonecrosis of the femoral head: a new understanding of the mechanisms of action

Glucocorticoid (GC) usage is the most common non-traumatic cause of osteonecrosis of the femoral head (ON). Despite the strong association of GC with ON, the underlying mechanisms have been unclear. Investigators have proposed both direct and indirect effects of GC on cells. Indirect and direct mechanisms remain intimately related and often result in positive feedback loops to potentiate the disease processes. However, the direct effects, in particular apoptosis, have recently been shown to be increasingly important. Suppression of osteoblast and osteoclast precursor production, increased apoptosis of osteoblasts and osteocytes, prolongation of the lifespan of osteoclasts and apoptosis of endothelial cells (EC) are all direct effects of GC usage. Elevated blood pressure through several pathways may raise the risk of clot formation. High-dose GC also decreases tissue plasminogen activator activity (t-PA) and increases plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels increasing the procoagulant potential of GC. Inhibited angiogenesis, altered bone repair and nitric oxide metabolism can also result. Also, GC treatment modulates other vasoactive mediators such as endothelin-1, noradrenalin and bradykinin. Thus, GCs act as a regulator of local blood flow by modulating vascular responsiveness to vasoactive substances. Vasoconstriction induced in intraosseous femoral head arteries causes femoral head ischemia. GCs also cause ischemia through increased intraosseous pressure, which subsequently decreases the blood flow to the femoral head by apoptosis of ECs as well as elevating the level of adipogenesis and fat hypertrophy in the bone marrow. It is difficult to predict which patients receiving a specific dose of GC will develop ON, indicating individual differences in steroid sensitivity and the potential of additional mechanisms. The textbook model of ON is a multiple hit theory in which, with a greater number of risk factors, the risk of ON increases. While more effort is needed to better comprehend the role of GC in ON, newer data on GC action upon the endothelial cell and the regional endothelial bed dysfunction theory sheds new light on particular GC mechanisms. Better understanding of GC pathomechanisms can lead to better treatment options.

Ethanol may suppress Wnt/beta-catenin signaling on human bone marrow stroma cells: a preliminary study

Ethanol and glucocorticoids are risk factors associated with osteonecrosis. Previous reports suggest ethanol and glucocorticoids induce adipogenesis, decrease osteogenesis in bone marrow stroma cells, and produce intracellular lipid deposits resulting in death of osteocytes. The Wnt/beta-catenin signal pathway is involved in the regulation of homeostasis of bone and we presume glucocorticoids and ethanol may induce osteonecrosis in humans through a similar mechanism as in rodents. We hypothesized (1) ethanol, like glucocorticoids, decreases osteogenesis and increases adipogenesis through the Wnt/beta-catenin signaling pathway in human bone marrow stromal cells; and (2) ethanol decreases intranuclear translocation of beta-catenin. We found both dexamethasone and ethanol decrease the gene and protein expression of osteogenesis and increase that of adipogenesis through Wnt signaling-related genes by semiquantitative and quantitative polymerase chain reaction and Western blot. Ethanol hampered intranuclear translocation of beta-catenin by immunofluorescence analysis. The data suggest the Wnt/beta-catenin signaling pathway may be associated with ethanol-induced osteonecrosis.

Effects of anti-inflammatory drugs on proliferation, cytotoxicity and osteogenesis in bone marrow mesenchymal stem cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) were found to suppress proliferation and induce cell death in cultured osteoblasts, and steroids were found to decrease the osteogenesis potential of mesenchymal stem cells. In this study, we further tested the effects of anti-inflammatory drugs (AIDs) on the functions of bone marrow mesenchymal stem cells (BMSCs). The BMSCs from mice (D1-cells) and humans (hBMSCs) were treated with dexamethasone (10(-7) to 10(-6) M), cyclooxygenase-2 (COX-2) selective NSAIDs (10(-6) to 10(-5) M) and non-selective NSAIDs (10(-5) to 10(-4) M). Drug effects on proliferation, cell cycle kinetics, cytotoxicity and mRNA and protein expressions of cell cycle regulators were tested. The osteogenesis potential of D1-cells were evaluated by testing mRNA expressions of type Ialpha collagen and osteocalcin 2-8 days after treatments, and testing mineralization 1-3 weeks after treatments. The results showed that all the tested drugs suppressed proliferation and arrested cell cycle of D1-cells, but no significant cytotoxic effects was found. Prostaglandin E1, E2 and F2alpha couldn't rescue the effects of AIDs on proliferation. The p27kip1 expression was up-regulated by indomethacin, celecoxib and dexamethasone in both D1-cells and hBMSCs. Higher concentrations of indomethacin and dexamethasone also up-regulated p21Cip1/Waf1 expression in hBMSCs, and so did celecoxib on D1-cells. Expressions of cyclin E1 and E2 were down-regulated by these AIDs in D-cells, while only cyclin E2 was down-regulated by dexamethasone in hBMSCs. All the tested NSAIDs revealed no obvious detrimental effects on osteogenic differentiation of D1-cells. These results suggest that the proliferation suppression of AIDs on BMSCs may act via affecting expressions of cell cycle regulators, but not prostaglandin-related mechanisms.