Resveratrol promotes osteogenic differentiation and protects against dexamethasone damage in murine induced pluripotent stem cells

Stem Cells in Bone Tissue Engineering: Progress, Promises and Challenges

Bone defects from accidents, congenital conditions, and age-related diseases significantly impact quality of life. Recent advancements in bone tissue engineering (TE) involve biomaterial scaffolds, patient-derived cells, and bioactive agents, enabling functional bone regeneration. Stem cells, obtained from numerous sources including umbilical cord blood, adipose tissue, bone marrow, and dental pulp, hold immense potential in bone TE. Induced pluripotent stem cells and genetically modified stem cells can also be used. Proper manipulation of physical, chemical, and biological stimulation is crucial for their proliferation, maintenance, and differentiation. Stem cells contribute to osteogenesis, osteoinduction, angiogenesis, and mineralization, essential for bone regeneration. This review provides an overview of the latest developments in stem cell-based TE for repairing and regenerating defective bones.

Emerging Landscape of Osteogenesis Imperfecta Pathogenesis and Therapeutic Approaches

Osteogenesis imperfecta (OI) is an uncommon genetic disorder characterized by shortness of stature, hearing loss, poor bone mass, recurrent fractures, and skeletal abnormalities. Pathogenic variations have been found in over 20 distinct genes that are involved in the pathophysiology of OI, contributing to the disorder's clinical and genetic variability. Although medications, surgical procedures, and other interventions can partially alleviate certain symptoms, there is still no known cure for OI. In this Review, we provide a comprehensive overview of genetic pathogenesis, existing treatment modalities, and new developments in biotechnologies such as gene editing, stem cell reprogramming, functional differentiation, and transplantation for potential future OI therapy.

Cellular direct conversion by cell penetrable OCT4-30Kc19 protein and BMP4 growth factor

Background

The number of patients suffering from osteoporosis is increasing as the elderly population increases. The demand for investigating bone regeneration strategies naturally arises. One of the approaches to induce bone regeneration is somatic cell transdifferentiation. Among the transcriptional regulators for transdifferentiation, octamer-binding transcription factor 4 (OCT4) is famous for its role in the regulation of pluripotency of stem cells. Bone morphogenetic protein 4 (BMP4) is another factor that is known to have a significant role in osteogenic differentiation. Previous studies have achieved transdifferentiation of cells into osteoblasts using viral and plasmid deliveries of these factors. Although these methods are efficient, viral and plasmid transfection have safety issues such as permanent gene incorporations and bacterial DNA insertions. Herein, we developed a cell penetrating protein-based strategy to induce transdifferentiation of endothelial cells into osteoblasts via nuclear delivery of OCT4 recombinant protein combined with the BMP4 treatment. For the nuclear delivery of OCT4 protein, we fused the protein with 30Kc19, a cell-penetrating and protein stabilizing protein derived from a silkworm hemolymph of Bombyx mori with low cytotoxic properties. This study proposes a promising cell-based therapy without any safety issues that existing transdifferentiation approaches had.

Methods

OCT4-30Kc19 protein with high penetrating activities and stability was synthesized for a protein-based osteogenic transdifferentiation system. Cells were treated with OCT4-30Kc19 and BMP4 to evaluate their cellular penetrating activity, cytotoxicity, osteogenic and angiogenic potentials in vitro. The osteogenic potential of 3D cell spheroids was also analyzed. In addition, in vivo cell delivery into subcutaneous tissue and cranial defect model was performed.

Results

OCT4-30Kc19 protein was produced in a soluble and stable form. OCT4-30Kc19 efficiently penetrated cells and were localized in intracellular compartments and the nucleus. Cells delivered with OCT4-30Kc19 protein combined with BMP4 showed increased osteogenesis, both in 2D and 3D culture, and showed increased angiogenesis capacity in vitro. Results from in vivo subcutaneous tissue delivery of cell-seeded scaffolds confirmed enhanced osteogenic properties of transdifferentiated HUVECs via treatment with both OCT4-30Kc19 and BMP4. In addition, in vivo mouse cranial defect experiment demonstrated successful bone regeneration of HUVECs pretreated with both OCT4-30Kc19 and BMP4.

Conclusions

Using a protein-based transdifferentiation method allows an alternative approach without utilizing any genetic modification strategies, thus providing a possibility for safer use of cell-based therapies in clinical applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00280-8.

Novel cell sources for bone regeneration

A plethora of both acute and chronic conditions, including traumatic, degenerative, malignant, or congenital disorders, commonly induce bone disorders often associated with severe persisting pain and limited mobility. Over 1 million surgical procedures involving bone excision, bone grafting, and fracture repair are performed each year in the U.S. alone, resulting in immense levels of public health challenges and corresponding financial burdens. Unfortunately, the innate self-healing capacity of bone is often inadequate for larger defects over a critical size. Moreover, as direct transplantation of committed osteoblasts is hindered by deficient cell availability, limited cell spreading, and poor survivability, an urgent need for novel cell sources for bone regeneration is concurrent. Thanks to the development in stem cell biology and cell reprogramming technology, many multipotent and pluripotent cells that manifest promising osteogenic potential are considered the regenerative remedy for bone defects. Considering these cells' investigation is still in its relative infancy, each of them offers their own particular challenges that must be conquered before the large-scale clinical application.

Bioinspired mineralized collagen scaffolds for bone tissue engineering

Successful regeneration of large segmental bone defects remains a major challenge in clinical orthopedics, thus it is of important significance to fabricate a suitable alternative material to stimulate bone regeneration. Due to their excellent biocompatibility, sufficient mechanical strength, and similar structure and composition of natural bone, the mineralized collagen scaffolds (MCSs) have been increasingly used as bone substitutes via tissue engineering approaches. Herein, we thoroughly summarize the state of the art of MCSs as tissue-engineered scaffolds for acceleration of bone repair, including their fabrication methods, critical factors for osteogenesis regulation, current opportunities and challenges in the future. First, the current fabrication methods for MCSs, mainly including direct mineral composite, in-situ mineralization and 3D printing techniques, have been proposed to improve their biomimetic physical structures in this review. Meanwhile, three aspects of physical (mechanics and morphology), biological (cells and growth factors) and chemical (composition and cross-linking) cues are described as the critical factors for regulating the osteogenic feature of MCSs. Finally, the opportunities and challenges associated with MCSs as bone tissue-engineered scaffolds are also discussed to point out the future directions for building the next generation of MCSs that should be endowed with satisfactorily mimetic structures and appropriately biological characters for bone regeneration.

The Role of Adipose Stem Cells in Bone Regeneration and Bone Tissue Engineering

Bone regeneration is a complex process that is influenced by tissue interactions, inflammatory responses, and progenitor cells. Diseases, lifestyle, or multiple trauma can disturb fracture healing, which might result in prolonged healing duration or even failure. The current gold standard therapy in these cases are bone grafts. However, they are associated with several disadvantages, e.g., donor site morbidity and availability of appropriate material. Bone tissue engineering has been proposed as a promising alternative. The success of bone-tissue engineering depends on the administered cells, osteogenic differentiation, and secretome. Different stem cell types offer advantages and drawbacks in this field, while adipose-derived stem or stromal cells (ASCs) are in particular promising. They show high osteogenic potential, osteoinductive ability, and immunomodulation properties. Furthermore, they can be harvested through a noninvasive process in high numbers. ASCs can be induced into osteogenic lineage through bioactive molecules, i.e., growth factors and cytokines. Moreover, their secretome, in particular extracellular vesicles, has been linked to fracture healing. The aim of this review is a comprehensive overview of ASCs for bone regeneration and bone tissue engineering.

Versatility of Induced Pluripotent Stem Cells (iPSCs) for Improving the Knowledge on Musculoskeletal Diseases

Induced pluripotent stem cells (iPSCs) represent an unlimited source of pluripotent cells capable of differentiating into any cell type of the body. Several studies have demonstrated the valuable use of iPSCs as a tool for studying the molecular and cellular mechanisms underlying disorders affecting bone, cartilage and muscle, as well as their potential for tissue repair. Musculoskeletal diseases are one of the major causes of disability worldwide and impose an important socio-economic burden. To date there is neither cure nor proven approach for effectively treating most of these conditions and therefore new strategies involving the use of cells have been increasingly investigated in the recent years. Nevertheless, some limitations related to the safety and differentiation protocols among others remain, which humpers the translational application of these strategies. Nonetheless, the potential is indisputable and iPSCs are likely to be a source of different types of cells useful in the musculoskeletal field, for either disease modeling or regenerative medicine. In this review, we aim to illustrate the great potential of iPSCs by summarizing and discussing the in vitro tissue regeneration preclinical studies that have been carried out in the musculoskeletal field by using iPSCs.

Enhancing induced pluripotent stem cell toward differentiation into functional cardiomyocytes

BACKGROUND

Heart diseases, especially myocardial ischemia, remain one of the leading causes of mortality worldwide and usually result in irreparable cardiomyocyte damage and severe heart failure. Recent advances in induced pluripotent stem cell (iPSC) technologies for applied regenerative medicine and stem cell research, especially for iPSC-derived cardiomyocytes have increased the hope for heart repair. However, the driver molecules of myocardial differentiation and the functional reconstruction capacity of iPSC-derived cardiomyocytes are still questionable.

METHODS

Herein, we established a rapid differentiated platform that is involved in cardiomyogenic differentiation and maturation from iPSCs in vitro. Functional analysis is performed in miR-181a-transfected iPSC-derived cardiomyocyte (iPSC-cardio/miR-181a) under a time-lapse microscope. In addition, we calculated the beating area and frequency of iPSC-cardio/miR-181a cells in the presence of HCN4 shRNA or miR-181a SPONGE.

RESULTS

miR-181a enhanced the beating area and maintained the beating frequency of iPSC-derived cardiomyocytes by enhancing HCN4 expression.

CONCLUSION

miR-181a would play a key role on maintaining proper beating function in iPSC-derived cardiomyocytes.

Using cationic polyurethane-short branch PEI as microRNA-driven nano-delivery system for stem cell differentiation

BACKGROUND

Non-viral gene delivery, such as using biodegradable polyurethane short-branch polyethylenimine (PU-PEI), has been considered a potentially safer gene delivery system in comparison to conventional virus systems.

METHODS

The polycationization of DNA complexes protects DNA from nuclease degradation, and these DNA complexes are nanoscale in size to enter the cell through endocytosis.

RESULTS

Due to the net positive surface charge of the cell, these polyplexes efficiently bind to the cell through electrostatic interactions with negatively charged membrane components. Cationic PU-PEI has been shown to be non-cytotoxic and has a high transfection efficiency, making it a practical gene delivery material in diseases.

CONCLUSION

We developed a PU-PEI nanomedicine-based platform to efficiently deliver microRNA in promoting differentiation capacity of stem cells, especially on induced pluripotent stem cells.

Resveratrol inhibits adipocyte differentiation and cellular senescence of human bone marrow stromal stem cells

Bone marrow adipose tissue (BMAT) is a unique adipose depot originating from bone marrow stromal stem cells (BMSCs) and regulates bone homeostasis and energy metabolism. An increased BMAT volume is observed in several conditions e.g. obesity, type 2 diabetes, osteoporosis and is known to be associated with bone fragility and increased risk for fracture. Therapeutic approaches to decrease the accumulation of BMAT are clinically relevant. In a screening experiment of natural compounds, we identified Resveratrol (RSV), a plant-derived antioxidant mediating biological effects via sirtuin- related mechanisms, to exert significant effects of BMAT formation. Thus, we examined in details the effects RSV on adipocytic and osteoblastic differentiation of tolermerized human BMSCs (hBMSC-TERT). RSV (1.0 μM) enhanced osteoblastic differentiation and inhibited adipocytic differentiation of hBMSC-TERT when compared with control and Sirtinol (Sirtuin inhibitor). Global gene expression profiling and western blot analysis revealed activation of a number of signaling pathways including focal adhesion kinase (FAK). Pharmacological inhibition of FAK using (PF-573228) and AKT inhibitor (LY-294002) (5μM), diminished RSV-induced osteoblast differentiation. In addition, RSV reduced the levels of senescence-associated secretory phenotype (SASP), gene markers associated with senescence (P53, P16, and P21), intracellular ROS levels and increased gene expression of enzymes protecting cells from oxidative damage (HMOX1 and SOD3). In vitro treatment of primary hBMSCs from aged patients characterized with high adipocytic and low osteoblastic differentiation ability with RSV, significantly enhanced osteoblast and decreased adipocyte formation when compared to hBMSCs from young donors. RSV targets hBMSCs and inhibits adipogenic differentiation and senescence-associated phenotype and thus a potential agent for treating conditions of increased BMAT formation.

Induced Pluripotent Stem Cells in Dental and Nondental Tissue Regeneration: A Review of an Unexploited Potential

Cell-based therapies currently represent the state of art for tissue regenerative treatment approaches for various diseases and disorders. Induced pluripotent stem cells (iPSCs), reprogrammed from adult somatic cells, using vectors carrying definite transcription factors, have manifested a breakthrough in regenerative medicine, relying on their pluripotent nature and ease of generation in large amounts from various dental and nondental tissues. In addition to their potential applications in regenerative medicine and dentistry, iPSCs can also be used in disease modeling and drug testing for personalized medicine. The current review discusses various techniques for the production of iPSC-derived osteogenic and odontogenic progenitors, the therapeutic applications of iPSCs, and their regenerative potential in vivo and in vitro. Through the present review, we aim to explore the potential applications of iPSCs in dental and nondental tissue regeneration and to highlight different protocols used for the generation of different tissues and cell lines from iPSCs.

Bioengineering strategies for bone and cartilage tissue regeneration using growth factors and stem cells

Bone and cartilage tissue engineering is an integrative approach that is inspired by the phenomena associated with wound healing. In this respect, growth factors have emerged as important moieties for the control and regulation of this process. Growth factors act as mediators and control the important physiological functions of bone regeneration. Herein, we discuss the importance of growth factors in bone and cartilage tissue engineering, their loading and delivery strategies, release kinetics, and their integration with biomaterials and stem cells to heal bone fractures. We also highlighted the role of growth factors in the determination of the bone tissue microenvironment based on the reciprocal signaling with cells and biomaterial scaffolds on which future bone and cartilage tissue engineering technologies and medical devices will be based upon.

Short-Term Protocols to Obtain Insulin-Producing Cells from Rat Adipose Tissue: Signaling Pathways and In Vivo Effect

Studies using mesenchymal stromal cells (MSCs) as a source of insulin-secreting cells (IPCs) are a promising path in the pursuit for diabetes therapy. Here, we investigate three short-term differentiation protocols in order to generate IPCs from autologous adipose-derived stromal cells (ADSCs) with an expressive insulin-secreting profile in vitro and in vivo, as well as the signaling pathways involved in the chosen differentiation protocols. We extracted and cultured ADSCs and differentiated them into IPCs, using three different protocols with different inductors. Afterwards, the secretory profile was analyzed and IPCs differentiated in exendin-4/activin A medium, which presented the best secretory profile, was implanted in the kidney subcapsular region of diabetic rats. All protocols induced the differentiation, but media supplemented with exendin-4/activin A or resveratrol induced the expression and secretion of insulin more efficiently, and only the exendin-4/activin-A-supplemented medium generated an insulin secretion profile more like β-cells, in response to glucose. The PI3K/Akt pathway seems to play a negative role in IPC differentiation; however, the differentiation of ADSCs with exendin-4/activin A positively modulated the p38/MAPK pathway. Resveratrol medium activated the Jak/STAT3 pathway and generated IPCs apparently less sensitive to insulin and insulin-like receptors. Finally, the implant of IPCs with the best secretory behavior caused a decrease in hyperglycemia after one-week implantation in diabetic rats. Our data provide further information regarding the generation of IPCs from ADSCs and strengthen evidence to support the use of MSCs in regenerative medicine, specially the use of exendin-4/activin A to produce rapid and effectively IPCs with significant in vivo effects.

Emerging opportunities for induced pluripotent stem cells in orthopaedics

The discovery of induced pluripotent stem cells (iPSCs) has revolutionized biomedicine. Although the potential of iPSCs for tissue regeneration, disease modeling and drug screening has been largely recognized, findings of iPSC research to date are mostly focused on neurology, cardiology and haematology. For orthopaedics, growing interest in the unique cell type has prompted more researchers to get involved in iPSC research. In this article, we introduce the brief history of cellular reprogramming and different reprogramming methods that have been developed, discuss the biology of iPSCs and review previously reported findings of iPSC studies in orthopaedics.

The Translational potential of this article

Stem cell therapies hold great promise for treating orthopaedic diseases, manifested in recent study findings and results of clinical trials. iPSCs are a unique stem cell type derived from a patient’s own cells while still possessing the embryonic stem cell-featured pluripotency for generation of all tissues in the body. The distinctive properties make iPSCs much desirable to fulfill the promise of regenerative medicine for clinical orthopaedics.

Bone Tissue Engineering Using Human Cells: A Comprehensive Review on Recent Trends, Current Prospects, and Recommendations

The use of proper cells for bone tissue engineering remains a major challenge worldwide. Cells play a pivotal role in the repair and regeneration of the bone tissue in vitro and in vivo. Currently, a large number of differentiated (somatic) and undifferentiated (stem) cells have been used for bone reconstruction alone or in combination with different biomaterials and constructs (e.g., scaffolds). Although the results of the cell transplantation without any supporting or adjuvant material have been very effective with regard to bone healing. Recent advances in bone scaffolding are now becoming new players affecting the osteogenic potential of cells. In the present study, we have critically reviewed all the currently used cell sources for bone reconstruction and discussed the new horizons that are opening up in the context of cell-based bone tissue engineering strategies.

Combination of resveratrol and 5-azacytydine improves osteogenesis of metabolic syndrome mesenchymal stem cells

Endocrine disorders have become more and more frequently diagnosed in humans and animals. In horses, equine metabolic syndrome (EMS) is characterized by insulin resistance, hyperleptinemia, hyperinsulinemia, inflammation and usually by pathological obesity. Due to an increased inflammatory response in the adipose tissue, cytophysiological properties of adipose derived stem cells (ASC) have been impaired, which strongly limits their therapeutic potential. Excessive accumulation of reactive oxygen species, mitochondria deterioration and accelerated ageing of those cells affect their multipotency and restrict the effectiveness of the differentiation process. In the present study, we have treated ASC isolated from EMS individuals with a combination of 5-azacytydine (AZA) and resveratrol (RES) in order to reverse their aged phenotype and enhance osteogenic differentiation. Using SEM and confocal microscope, cell morphology, matrix mineralization and mitochondrial dynamics were assessed. Furthermore, we investigated the expression of osteogenic-related genes with RT-PCR. We also investigated the role of autophagy during differentiation and silenced PARKIN expression with siRNA. Obtained results indicated that AZA/RES significantly enhanced early osteogenesis of ASC derived from EMS animals. Increased matrix mineralization, RUNX-2, collagen type I and osteopontin levels were noted. Furthermore, we proved that AZA/RES exerts its beneficial effects by modulating autophagy and mitochondrial dynamics through PARKIN and RUNX-2 activity.

Reprogramming of Mouse Calvarial Osteoblasts into Induced Pluripotent Stem Cells

Previous studies have demonstrated the ability of reprogramming endochondral bone into induced pluripotent stem (iPS) cells, but whether similar phenomenon occurs in intramembranous bone remains to be determined. Here we adopted fluorescence-activated cell sorting-based strategy to isolate homogenous population of intramembranous calvarial osteoblasts from newborn transgenic mice carrying both Osx1-GFP::Cre and Oct4-EGFP transgenes. Following retroviral transduction of Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc), enriched population of osteoblasts underwent silencing of Osx1-GFP::Cre expression at early stage of reprogramming followed by late activation of Oct4-EGFP expression in the resulting iPS cells. These osteoblast-derived iPS cells exhibited gene expression profiles akin to embryonic stem cells and were pluripotent as demonstrated by their ability to form teratomas comprising tissues from all germ layers and also contribute to tail tissue in chimera embryos. These data demonstrate that iPS cells can be generated from intramembranous osteoblasts.

The postpartum effect of maternal diabetes on the circulating levels of sirtuins and superoxide dismutase

Gestational diabetes mellitus (GDM) is a glucose intolerance disorder which occurs during pregnancy as a result of insulin insensitivity; it usually disappears after delivery. However, some women with GDM can develop type 2 diabetes (T2D) after delivery, and the mechanisms by which this occurs remain unknown. This study compared the levels of sirtuins (NAD‐dependent deacetylases) and antioxidative enzymes in postpartum women with previous GDM (pGDM) or T2D and in postpartum women with a previous healthy pregnancy (controls). Women with pGDM showed upregulated levels of sirtuin 1 (SIRT1) mRNA and protein, with reduced expression levels of sirtuin 3 (SIRT3) and superoxide dismutase 2 (SOD2), relative to the controls. Women with T2D similarly showed a lower level of SIRT3 mRNA than the controls. Lipid peroxidation (malondialdehyde) was higher in women with pGDM than in the controls. These data show that in women with pGDM, the reduced level of SIRT3 may play a role in the reduced SOD2 level, possibly leading to oxidative stress, which, in turn, upregulates the level of SIRT1. These results might confer the risk of future diabetes development in women with pGDM, as a similar reduction in SIRT3 was found in women with T2D.

DHEA supplementation to dexamethasone-treated rabbits alleviates oxidative stress in kidney-cortex and attenuates albuminuria

Our recent study has shown that dehydroepiandrosterone (DHEA) administered to rabbits partially ameliorated several dexamethasone (dexP) effects on hepatic and renal gluconeogenesis, insulin resistance and plasma lipid disorders. In the current investigation, we present the data on DHEA protective action against dexP-induced oxidative stress and albuminuria in rabbits. Four groups of adult male rabbits were used in the in vivo experiment: (1) control, (2) dexP-treated, (3) DHEA-treated and (4) both dexP- and DHEA-treated. Administration of dexP resulted in accelerated generation of renal hydroxyl free radicals (HFR) and malondialdehyde (MDA), accompanied by diminished superoxide dismutase (SOD) and catalase activities and a dramatic rise in urinary albumin/creatinine ratio. Treatment with DHEA markedly reduced dexP-induced oxidative stress in kidney-cortex due to a decline in NADPH oxidase activity and enhancement of catalase activity. Moreover, DHEA effectively attenuated dexP-evoked albuminuria. Surprisingly, dexP-treated rabbits exhibited elevation of GSH/GSSG ratio, accompanied by a decrease in glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities as well as an increase in glucose-6-phosphate dehydrogenase (G6PDH) activity. Treatment with DHEA resulted in a decline in GSH/GSSG ratio and glutathione reductase (GR) activity, accompanied by an elevation of GPx activity. Interestingly, rabbits treated with both dexP and DHEA remained the control values of GSH/GSSG ratio. As the co-administration of DHEA with dexP resulted in (i) reduction of oxidative stress in kidney-cortex, (ii) attenuation of albuminuria and (iii) normalization of glutathione redox state, DHEA might limit several undesirable renal side effects during chronic GC treatment of patients suffering from allergies, asthma, rheumatoid arthritis and lupus. Moreover, its supplementation might be particularly beneficial for the therapy of patients with glucocorticoid-induced diabetes.

Resveratrol did not alter blood pressure in rats with nitric oxide synthase-inhibited hypertension

Background:

Inhibition of nitric oxide synthase (NOS) is a well-known experimental model of hypertension (HT). It was shown that oxidative stress contributes to the pathogenesis of HT. Resveratrol is a potent anti-oxidant that is found in red grapes, peanuts and red wine. It improves the NO response and increases endothelial NOS expression, which causes endothelium-dependent vasorelaxation as well as renal vasodilation. We aimed to explore the effects of resveratrol on blood pressure, the water–salt balance and sodium excretion as a reflection of renal function in NOS-inhibited rat models.

Methods:

Thirty-five male Sprague-Dawley rats (200–250g) were used in this study. In order to obtain hypertension models, an NOS inhibitor, N-nitro-L-arginin (L-NNA) was used. The rats were randomly divided into five groups: controls (given water and 0.8% salty diet) and four groups [given L-NNA, resveratrol (RSV) eluent, RSV, and L-NNA + RSV]. Blood pressures were measured indirectly by the tailcuff method on the first, seventh and 10th days. At the end of the study protocol (10th day), fluid balance, glomerular filtration rate, fractional sodium excretion, and blood and urinesodium and creatinine levels were measured.

Results:

At the end of the study protocol, blood pressures were higher in only the L-NNA group (117.8 ± 3.5 vs 149.5 ± 2.1 mmHg; p < 0.05), as expected. Additional applications of RSV with L-NNA could not prevent the increase in blood pressure (122.8 ± 7.3 vs 155.4 ± 4.4 mmHg; p < 0.05). There were no remarkable changes in water–salt balance and renal function with the application of resveratrol.

Conclusion:

Resveratrol was unable to prevent or reverse blood pressure increase in NOS-inhibited rats.

Induced pluripotent stem cells reduce neutrophil chemotaxis via activating GRK2 in endotoxin-induced acute lung injury

BACKGROUND AND OBJECTIVE

We investigated the effect of induced pluripotent stem cells (iPSCs) in moderating neutrophil chemotaxis in endotoxin-induced acute lung injury (ALI).

METHODS

Male C57BL/6 mice at 8-12 weeks of age were studied. Murine iPSCs were delivered through the tail veins of mice 4 h after intratracheal instillation of endotoxin. Lung histopathological findings, neutrophil counts in peripheral blood and bronchoalveolar lavage fluid (BALF), bone marrow (BM) cell distribution, expression of chemokine receptors and regulatory signalling pathways were analysed after 24 h. Human neutrophils isolated from acute respiratory distress syndrome patients were used in a cell migration assay.

RESULTS

iPSCs significantly decreased the histopathological changes of ALI in mice compared to treatment with control cells. Numbers and activity levels of neutrophils in BALF were reduced in iPSC-treated ALI mice. The iPSC therapy restored neutrophil counts in the peripheral blood of ALI mice, but the percentages of mature neutrophils in BM were similar between iPSC-treated and -untreated groups. The iPSCs mediated a downregulation of the chemotactic response to endotoxin by reducing chemokine (C-X-C motif) receptor 2 (CXCR2) expression on mouse peripheral blood neutrophils. This result was confirmed by an in vitro human neutrophil migration assay. In addition, iPSCs or conditioned medium from iPSCs enhanced expression of G protein-coupled receptor kinase 2 (GRK2) on the surface of blood neutrophils in ALI mice.

CONCLUSION

iPSCs reduce neutrophil chemotaxis in endotoxin-induced ALI. These effects are associated with an enhancement of GRK2 activity and reduction of CXCR2 expression.

Induced pluripotent stem cells as a new getaway for bone tissue engineering: A systematic review

OBJECTIVES

Mesenchymal stem cells (MSCs) are frequently used for bone regeneration, however, they are limited in quantity. Moreover, their proliferation and differentiation capabilities reduce during cell culture expansion. Potential application of induced pluripotent stem cells (iPSCs) has been reported as a promising alternative source for bone regeneration. This study aimed to systematically review the available literature on osteogenic potential of iPSCs and to discuss methods applied to enhance their osteogenic potential.

METHODS AND MATERIALS

A thorough search of MEDLINE database was performed from January 2006 to September 2016, limited to English-language articles. All in vitro and in vivo studies on application of iPSCs in bone regeneration were included.

RESULTS

The current review is organized according to the PRISMA statement. Studies were categorized according to three different approaches used for osteo-induction of iPSCs. Data are summarized and reported according to the following variables: types of study, cell sources used for iPSC generation, applied reprogramming methods, applied osteo-induction methods and treatment groups.

CONCLUSION

According to the articles reviewed, osteo-induced iPSCs revealed osteogenic capability equal to or superior than MSCs; cell sources do not significantly affect osteogenic potential of iPSCs; addition of resveratrol to the osteogenic medium (OM) and irradiatiation after osteogenic induction reduce teratoma formation in animal models; transfection with lentiviral bone morphogenetic protein 2 results in higher mineralization compared to osteo-induction in OM; addition of TGF-β, IGF-1 and FGF-β to OM increases osteogenic capability of iPSCs.

Resveratrol Enhances Self-Renewal of Mouse Embryonic Stem Cells

Resveratrol (RSV) has been shown to affect the differentiation of several types of stem cells, while the detailed mechanism is elusive. Here, we aim to investigate the function of RSV in self-renewal of mouse embryonic stem cells (ESCs) and the related mechanisms. In contrast with its reported roles, we found unexpectedly that differentiated ESCs or iPSCs treated by RSV would not show further differentiation, but regained a naïve pluripotency state with higher expressions of core transcriptional factors and with the ability to differentiate into all three germ layers when transplanted in vivo. In accordance with these findings, RSV also enhanced cell cycle progression of ESCs via regulating cell cycle-related proteins. Finally, enhanced activation of JAK/STAT3 signaling pathway and suppressed activation of mTOR were found essential in enhancing the self-renewal of ESCs by RSV. Our finding discovered a novel function of RSV in enhancing the self-renewal of ESCs, and suggested that the timing of treatment and concentration of RSV determined the final effect of it. Our work may contribute to understanding of RSV in the self-renewal maintenance of pluripotent stem cells, and may also provide help to the generation and maintenance of iPSCs in vitro. J. Cell. Biochem. 118: 1928-1935, 2017. © 2017 Wiley Periodicals, Inc.

iPS cell technologies and their prospect for bone regeneration and disease modeling: A mini review

Bone disorders are a group of varied acute and chronic traumatic, degenerative, malignant or congenital conditions affecting the musculoskeletal system. They are prevalent in society and, with an ageing population, the incidence and impact on the population’s health is growing. Severe persisting pain and limited mobility are the major symptoms of the disorder that impair the quality of life in affected patients. Current therapies only partially treat the disorders, offering management of symptoms, or temporary replacement with inert materials. However, during the last few years, the options for the treatment of bone disorders have greatly expanded, thanks to the advent of regenerative medicine. Skeletal cell-based regeneration medicine offers promising reparative therapies for patients. Mesenchymal stem (stromal) cells from different tissues have been gradually translated into clinical practice; however, there are a number of limitations. The introduction of reprogramming methods and the subsequent production of induced pluripotent stem cells provides a possibility to create human-specific models of bone disorders. Furthermore, human-induced pluripotent stem cell-based autologous transplantation is considered to be future breakthrough in the field of regenerative medicine. The main goal of the present paper is to review recent applications of induced pluripotent stem cells in bone disease modeling and to discuss possible future therapy options. The present article contributes to the dissemination of scientific and pre-clinical results between physicians, mainly orthopedist and thus supports the translation to clinical practice.

Polyurethane–polylactide-based material doped with resveratrol decreases senescence and oxidative stress of adipose-derived mesenchymal stromal stem cell (ASCs)

The aim of this study was to evaluate the influence of resveratrol (RES)-doped polyurethane (TPU)–polylactide (PLA) biomaterials on the senescence and oxidative stress factor of adipose-derived stem cells (ASCs) for tissue engineering.

Characterization and comparison of osteoblasts derived from mouse embryonic stem cells and induced pluripotent stem cells

New developments in stem cell biology offer alternatives for the reconstruction of critical-sized bone defects. One of these developments is the use of induced pluripotent stem (iPS) cells. These stem cells are similar to embryonic stem (ES) cells, but can be generated from adult somatic cells and therefore do not raise ethical concerns. Proper characterization of iPS-derived osteoblasts is important for future development of safe clinical applications of these cells. For this reason, we differentiated mouse ES and iPS cells toward osteoblasts using osteogenic medium and compared their functionality. Immunocytochemical analysis showed significant expression of bone markers (osteocalcin and collagen type I) in osteoblasts differentiated from ES and iPS cells on days 7 and 30. An in vitro mineralization assay confirmed the functionality of osteogenically differentiated ES and iPS cells. Gene expression arrays focusing on osteogenic differentiation were performed in order to compare the gene expression pattern in both differentiated and undifferentiated ES cells and iPS cells. We observed a significant upregulation of osteogenesis-related genes such as Runx2, osteopontin, collagen type I, Tnfsf11, Csf1, and alkaline phosphatase upon osteogenic differentiation of the ES and iPS cells. We further validated the expression of key osteogenic genes Runx2, osteopontin, osteocalcin, collagen type I, and osterix in both differentiated and undifferentiated ES and iPS cells by means of quantified real-time polymerase chain reaction. We conclude that ES and iPS cells are similar in their osteogenic differentiation capacities, as well as in their gene expression patterns.

Orthopedic tissue regeneration: cells, scaffolds, and small molecules

Orthopedic tissue regeneration would benefit the aging population or patients with degenerative bone and cartilage diseases, especially osteoporosis and osteoarthritis. Despite progress in surgical and pharmacological interventions, new regenerative approaches are needed to meet the challenge of creating bone and articular cartilage tissues that are not only structurally sound but also functional, primarily to maintain mechanical integrity in their high load-bearing environments. In this review, we discuss new advances made in exploiting the three classes of materials in bone and cartilage regenerative medicine--cells, biomaterial-based scaffolds, and small molecules--and their successes and challenges reported in the clinic. In particular, the focus will be on the development of tissue-engineered bone and cartilage ex vivo by combining stem cells with biomaterials, providing appropriate structural, compositional, and mechanical cues to restore damaged tissue function. In addition, using small molecules to locally promote regeneration will be discussed, with potential approaches that combine bone and cartilage targeted therapeutics for the orthopedic-related disease, especially osteoporosis and osteoarthritis.

Iron overload inhibits osteogenic commitment and differentiation of mesenchymal stem cells via the induction of ferritin

Osteogenic differentiation of multipotent mesenchymal stem cells (MSCs) plays a crucial role in bone remodeling. Numerous studies have described the deleterious effect of iron overload on bone density and microarchitecture. Excess iron decreases osteoblast activity, leading to impaired extracellular matrix (ECM) mineralization. Additionally, iron overload facilitates osteoclast differentiation and bone resorption. These processes contribute to iron overload-associated bone loss. In this study we investigated the effect of iron on osteogenic differentiation of human bone marrow MSCs (BMSCs), the third player in bone remodeling. We induced osteogenic differentiation of BMSCs in the presence or absence of iron (0-50μmol/L) and examined ECM mineralization, Ca content of the ECM, mRNA and protein expressions of the osteogenic transcription factor runt-related transcription factor 2 (Runx2), and its targets osteocalcin (OCN) and alkaline phosphatase (ALP). Iron dose-dependently attenuated ECM mineralization and decreased the expressions of Runx2 and OCN. Iron accomplished complete inhibition of osteogenic differentiation of BMSCs at 50μmol/L concentration. We demonstrated that in response to iron BMSCs upregulated the expression of ferritin. Administration of exogenous ferritin mimicked the anti-osteogenic effect of iron, and blocked the upregulation of Runx2, OCN and ALP. Iron overload in mice was associated with elevated ferritin and decreased Runx2 mRNA levels in compact bone osteoprogenitor cells. The inhibitory effect of iron is specific toward osteogenic differentiation of MSCs as neither chondrogenesis nor adipogenesis were influenced by excess iron. We concluded that iron and ferritin specifically inhibit osteogenic commitment and differentiation of BMSCs both in vitro and in vivo.

Induced Pluripotent Stem Cells as a new Strategy for Osteogenesis and Bone Regeneration

Induced pluripotent stem (iPS) cells, possess high proliferation and differentiation ability, are now considered an attractive option for osteogenic differentiation and bone regeneration. In fact, recent discoveries have demonstrated that iPS cells can be differentiated into osteoblasts, suggesting that iPS cells have the potential to advance future bone regenerative therapies. Herein, we provide an overview of the recent findings on osteogenic characteristics and differentiation potential of iPS cells. In addition, we discuss current methods for inducing their specification towards osteogenic phenotype as well as in vivo evidence supporting the therapeutic benefit of iPS-derived osteoblasts. Finally, we describe recent findings regarding the use of iPS-derived cells for osteogenic differentiation and bone regeneration, which have indicated that these pluripotent cells represent an ideal tool for regenerative cell therapies and might contribute to the development of future bone tissue engineering.

The stimulation of osteogenic differentiation of embryoid bodies from human induced pluripotent stem cells by akermanite bioceramics

Induced pluripotent stem cells (iPSCs) have great potential as seed cells for tissue engineering applications. Previous studies have shown that iPSCs could be induced to differentiate into bone forming cells. However, in a tissue engineering approach, seeding cells in biomaterials is required, and the effect of biomaterials on cell growth and differentiation is critical for the success of the formation of engineered tissues. In this study, we investigated the effect of akermanite, a bioactive ceramic, on the osteogenic differentiation of embryoid body (EB) cells derived from human iPSCs. The results showed that, in the presence of osteogenic factors (ascorbic acid, dexamethasone, and β-glycerophosphate), ionic extracts of akermanite enhanced the osteogenic differentiation of EB cells as compared with normal osteogenic medium. Alkaline phosphatase (ALP) activity and the expression of osteogenic marker genes such as osteocalcin (OCN), collagen (COL-1), RUNX2, and BMP2 are significantly increased by the stimulation of akermanite ceramic extracts at certain concentration ranges. More interesting is that the medium containing extracts of akermanite but without osteogenic factors also showed stimulatory effects on the osteogenic differentiation of EB cells as compared to normal growth medium without osteogenic factors, such as ascorbic acid, dexamethasone, and β-glycerophosphate, not at the early stage of culture, but only at the later stage of the culture period (21 days). These results suggest that akermanite as a bioactive material together with human iPSCs might be used for bone tissue engineering applications.

Activating AMP-activated protein kinase by an α1 selective activator compound 13 attenuates dexamethasone-induced osteoblast cell death

Excessive glucocorticoid (GC) usage may lead to non-traumatic femoral head osteonecrosis. Dexamethasone (Dex) exerts cytotoxic effect to cultured osteoblasts. Here, we investigated the potential activity of Compound 13 (C13), a novel α1 selective AMP-activated protein kinase (AMPK) activator, against the process. Our data revealed that C13 pretreatment significantly attenuated Dex-induced apoptosis and necrosis in both osteoblastic-like MC3T3-E1 cells and primary murine osteoblasts. AMPK activation mediated C13' cytoprotective effect in osteoblasts. The AMPK inhibitor Compound C, shRNA-mediated knockdown of AMPKα1, or dominant negative mutation of AMPKα1 (T172A) almost abolished C13-induced AMPK activation and its pro-survival effect in osteoblasts. On the other hand, forced AMPK activation by adding AMPK activator A-769662 or exogenous expression a constitutively-active (ca) AMPKα1 (T172D) mimicked C13's actions and inhibited Dex-induced osteoblast cell death. Meanwhile, A-769662 or ca-AMPKα1 almost nullified C13's activity in osteoblast. Further studies showed that C13 activated AMPK-dependent nicotinamide adenine dinucleotide phosphate (NADPH) pathway to inhibit Dex-induced reactive oxygen species (ROS) production in MC3T3-E1 cells and primary murine osteoblasts. Such effects by C13 were almost reversed by Compound C or AMPKα1 depletion/mutation. Together, these results suggest that C13 alleviates Dex-induced osteoblast cell death via activating AMPK signaling pathway.

Resveratrol Enhances Cardiomyocyte Differentiation of Human Induced Pluripotent Stem Cells through Inhibiting Canonical WNT Signal Pathway and Enhancing Serum Response Factor-miR-1 Axis

Resveratrol (trans-3,5,4′-trihydroxystilbene) (RSV) is a natural polyphenol with protective effects over cardiac tissues and can affect cell survival and differentiation in cardiac stem cells transplantation. However, whether this agent can affect cardiomyocytes (CMs) differentiation of induced pluripotent stem cells (iPSCs) is not yet clear. This study explored whether RSV can affect CMs differentiation of human iPSCs. Under embryoid bodies (EBs) condition, the effect of RSV on the change of pluripotent markers, endoderm markers, mesoderm markers, and ectoderm markers was measured using qRT-PCR. Under CM differentiation culture, the effect of RSV on CM specific markers was also measured. The regulative role of RSV over canonical Wnt signal pathway and serum response factor- (SRF-) miR-1 axis and the functions of these two axes were further studied. Results showed that RSV had no effect on the self-renewal of human iPSCs but could promote mesoderm differentiation. Under CM differentiation culture, RSV could promote CM differentiation of human iPSCs through suppressing canonical Wnt signal pathway and enhancing SRF-miR-1 axis.

Hepatic differentiation of rat induced pluripotent stem cells in vitro

AIM: To show the efficient generation of hepatocyte-like cells (HLCs) differentiated from the induced pluripotent stem cells (iPSCs) of rats.

METHODS: Hepatic differentiation was achieved using a three-step protocol with several growth factors. First, rat iPSCs were differentiated into definitive endoderm cells using Activin A and Wnt3a treatment. Then fibroblast growth factor 4 and bone morphogenetic protein 2 were added to the culture medium and used to induce hepatic differentiation. Finally, hepatocyte growth factor, Oncostatin M and dexamethasone were used for hepatic maturation. The liver-related markers and functions of HLCs were assessed at the gene and protein levels.

RESULTS: After endodermal induction, the differentiated cells expressed endodermal markers forkhead box protein A2 and SRY-box containing gene 17 at the mRNA and protein levels. After 20 d of culture, the iPSCs were differentiated into HLCs. These differentiated cells expressed hepatic markers including α-fetoprotein, albumin CK8, CK18, CK19, and transcription factor HNF-4α. In addition, the cells expressed functional proteins such as α1-antitrypsin, cytochrome P450 1A2 and CYP 3A4. They acted like healthy hepatic cells, storing glycogen and taking up indocyanine green and low-density lipoproteins. Also, the rates of urea synthesis (20 d 1.202 ± 0.080 mg/dL vs 0 d 0.317 ± 0.021 mg/dL, P < 0.01) and albumin secretion (20 d 1.601 ± 0.102 mg/dL vs 0 d 0.313 ± 0.015 mg/dL, P < 0.01) increased significantly as differentiation progressed.

CONCLUSION: Rat iPSCs can differentiate into HLCs rapidly and efficiently. These differentiated cells may be an attractive resource for treatment of end-stage liver disease.

Small molecules and their controlled release that induce the osteogenic/chondrogenic commitment of stem cells

Stem cell-based tissue engineering plays a significant role in skeletal system repair and regenerative therapies. However, stem cells must be differentiated into specific mature cells prior to implantation (direct implantation may lead to tumour formation). Natural or chemically synthesised small molecules provide an efficient, accurate, reversible, and cost-effective way to differentiate stem cells compared with bioactive growth factors and gene-related methods. Thus, investigating the influences of small molecules on the differentiation of stem cells is of great significance. Here, we review a series of small molecules that can induce or/and promote the osteogenic/chondrogenic commitment of stem cells. The controlled release of these small molecules from various vehicles for stem cell-based therapies and tissue engineering applications is also discussed. The extensive studies in this field represent significant contributions to stem cell-based tissue engineering research and regenerative medicine.

Stem cell technology for bone regeneration: current status and potential applications

Continued improvements in the understanding and application of mesenchymal stem cells (MSC) have revolutionized tissue engineering. This is particularly true within the field of skeletal regenerative medicine. However, much remains unknown regarding the native origins of MSC, the relative advantages of different MSC populations for bone regeneration, and even the biologic safety of such unpurified, grossly characterized cells. This review will first summarize the initial discovery of MSC, as well as the current and future applications of MSC in bone tissue engineering. Next, the relative advantages and disadvantages of MSC isolated from distinct tissue origins are debated, including the MSC from adipose, bone marrow, and dental pulp, among others. The perivascular origin of MSC is next discussed. Finally, we briefly comment on pluripotent stem cell populations and their possible application in bone tissue engineering. While continually expanding, the field of MSC-based bone tissue engineering and regeneration shows potential to become a clinical reality in the not-so-distant future.

Improvement of In Vitro Osteogenic Potential through Differentiation of Induced Pluripotent Stem Cells from Human Exfoliated Dental Tissue towards Mesenchymal-Like Stem Cells

Constraints for the application of MSCs for bone reconstruction include restricted self-renewal and limited cell amounts. iPSC technology presents advantages over MSCs, providing homogeneous cellular populations with prolonged self-renewal and higher plasticity. However, it is unknown if the osteogenic potential of iPSCs differs from that of MSCs and if it depends on the iPSCs originating cellular source. Here, we compared the in vitro osteogenesis between stem cells from human deciduous teeth (SHED) and MSC-like cells from iPSCs from SHED (iPS-SHED) and from human dermal fibroblasts (iPS-FIB). MSC-like cells from iPS-SHED and iPS-FIB displayed fibroblast-like morphology, downregulation of pluripotency markers and upregulation of mesenchymal markers. Comparative in vitro osteogenesis analysis showed higher osteogenic potential in MSC-like cells from iPS-SHED followed by MSC-like cells from iPS-FIB and SHED. CD105 expression, reported to be inversely correlated with osteogenic potential in MSCs, did not display this pattern, considering that SHED presented lower CD105 expression. Higher osteogenic potential of MSC-like cells from iPS-SHED may be due to cellular homogeneity and/or to donor tissue epigenetic memory. Our findings strengthen the rationale for the use of iPSCs in bone bioengineering. Unveiling the molecular basis behind these differences is important for a thorough use of iPSCs in clinical scenarios.

RhoGTPases as key players in mammalian cell adaptation to microgravity

A growing number of studies are revealing that cells reorganize their cytoskeleton when exposed to conditions of microgravity. Most, if not all, of the structural changes observed on flown cells can be explained by modulation of RhoGTPases, which are mechanosensitive switches responsible for cytoskeletal dynamics control. This review identifies general principles defining cell sensitivity to gravitational stresses. We discuss what is known about changes in cell shape, nucleus, and focal adhesions and try to establish the relationship with specific RhoGTPase activities. We conclude by considering the potential relevance of live imaging of RhoGTPase activity or cytoskeletal structures in order to enhance our understanding of cell adaptation to microgravity-related conditions.

NADPH oxidases in bone homeostasis and osteoporosis

Bone formation and degradation are perfectly coordinated. In case of an imbalance of these processes diseases occur associated with exaggerated formation of new bone or bone loss as in osteoporosis. Most studies investigating osteoporosis either focus on osteoblast or osteoclast function and differentiation. Both processes have been suggested to be affected by reactive oxygen species (ROS). Besides a potentially harmful role of ROS, these small molecules are important second messengers. The family of NADPH oxidases produces ROS in a controlled and targeted manner, to specifically regulate signal transduction. This review will highlight the role of reactive oxygen species in bone cell differentiation and bone-loss associated disease with a special focus on osteoporosis and NADPH oxidases as specialized sources of ROS.

Dexamethasone altered steroidogenesis and changed redox status of granulosa cells

Glucocorticoids have been widely used in clinical application for anti-inflammatory and immunosuppressive function. Previous study reported that glucocorticoids adversely affect the reproductive system and can directly act on ovary. Here, we found that progesterone production induced by dexamethasone requiring activation of caspase-3 which may mediate differentiation and apoptosis of granulosa cells. Further study displayed that cellular glutathione level was increased and reactive oxygen species was decreased accompanied with unchanged mitochondrial membrane potential which may contribute to the maintenance of steroidogenesis in granulosa cells treated with dexamethasone. Dexamethasone also augmented the level of anti-Müllerian hormone secreted by preovulatory granulosa cells which indicated that dexamethasone may promote preantral follicles development.

Activation of AMPK participates hydrogen sulfide-induced cyto-protective effect against dexamethasone in osteoblastic MC3T3-E1 cells

Long-time glucocorticoids (GCs) usage causes osteoporosis. In the present study, we explored the potential role of hydrogen sulfide (H2S) against dexamethasone (Dex)-induced osteoblast cell damage, and focused on the underlying mechanisms. We showed that two H2S-producing enzymes, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), were significantly downregulated in human osteonecrosis tissues as well as in Dex-treated osteoblastic MC3T3-E1 cells. H2S donor NaHS as well as the CBS activator S-adenosyl-l-methionine (SAM) inhibited Dex-induced viability reduction, death and apoptosis in MC3T3-E1 cells. NaHS activated adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling, which participated its cyto-protective activity. AMPK inhibition by its inhibitor (compound C) or reduction by targeted-shRNA suppressed its pro-survival activity against Dex in MC3T3-E1 cells. Further, we found that NaHS inhibited Dex-mediated reactive oxygen species (ROS) production and ATP depletion. Such effects by NaHS were again inhibited by compound C and AMPKα1-shRNA. In summary, we show that H2S inhibits Dex-induced osteoblast damage through activation of AMPK signaling. H2S signaling might be further investigated as a novel target for anti-osteoporosis treatment.

Induced pluripotent stem cells without c-Myc ameliorate retinal oxidative damage via paracrine effects and reduced oxidative stress in rats

PURPOSE

To investigate the efficacy and mechanisms of non-c-Myc induced pluripotent stem cell (iPSC) transplantation in a rat model of retinal oxidative damage.

METHODS

Paraquat was intravitreously injected into Sprague-Dawley rats. After non-c-Myc iPSC transplantation, retinal function was evaluated by electroretinograms (ERGs). The generation of reactive oxygen species (ROS) was determined by lucigenin- and luminol-enhanced chemiluminescence. The expression of brain-derived neurotrophic factor, ciliary neurotrophic factor, basic fibroblast growth factor (bFGF), stromal cell-derived factor (SDF)-1α, and CXCR4 was measured by immunohistochemistry and ELISA. An in vitro study using SH-SY5Y cells was performed to verify the protective effects of SDF-1α.

RESULTS

Transplantation of non-c-Myc iPSCs effectively promoted the recovery of the b-wave ratio in ERGs and significantly ameliorated retinal damage. Non-c-Myc iPSC transplantation decreased ROS production and increased the activities of superoxide dismutase and catalase, thereby reducing retinal oxidative damage and apoptotic cells. Moreover, non-c-Myc iPSC transplantation resulted in significant upregulation of SDF-1α, followed by bFGF, accompanied by a significant improvement in the ERG. In vitro studies confirmed that treatment with SDF-1α significantly reduced apoptosis in a dose-dependent manner in SH-SY5Y cells. Most transplanted cells remained in the subretinal space, with spare cells expressing neurofilament M markers at day 28. Six months after transplantation, no tumor formation was seen in animals with non-c-Myc iPSC grafts.

CONCLUSIONS

We demonstrated the potential benefits of non-c-Myc iPSC transplantation for treating oxidative-damage-induced retinal diseases. SDF-1α and bFGF play important roles in facilitating the amelioration of retinal oxidative damage after non-c-Myc iPSC transplantation.

Comparative analysis of mouse-induced pluripotent stem cells and mesenchymal stem cells during osteogenic differentiation in vitro

Induced pluripotent stem cells (iPSCs) can differentiate into mineralizing cells and are, therefore, expected to be useful for bone regenerative medicine; however, the characteristics of iPSC-derived osteogenic cells remain unclear. Here, we provide a direct in vitro comparison of the osteogenic differentiation process in mesenchymal stem cells (MSCs) and iPSCs from adult C57BL/6J mice. After 30 days of culture in osteogenic medium, both MSCs and iPSCs produced robustly mineralized bone nodules that contained abundant calcium phosphate with hydroxyapatite crystal formation. Mineral deposition was significantly higher in iPSC cultures than in MSC cultures. Scanning electron microscopy revealed budding matrix vesicles in early osteogenic iPSCs; subsequently, the vesicles propagated to exhibit robust mineralization without rich fibrous structures. Early osteogenic MSCs showed deposition of many matrix vesicles in abundant collagen fibrils that became solid mineralized structures. Both cell types demonstrated increased expression of osteogenic marker genes, such as runx2, osterix, dlx5, bone sialoprotein (BSP), and osteocalcin, during osteogenesis; however, real-time reverse transcription-polymerase chain reaction array analysis revealed that osteogenesis-related genes encoding mineralization-associated molecules, bone morphogenetic proteins, and extracellular matrix collagens were differentially expressed between iPSCs and MSCs. These data suggest that iPSCs are capable of differentiation into mature osteoblasts whose associated hydroxyapatite has a crystal structure similar to that of MSC-associated hydroxyapatite; however, the transcriptional differences between iPSCs and MSCs could result in differences in the mineral and matrix environments of the bone nodules. Determining the biological mechanisms underlying cell-specific differences in mineralization during in vitro iPSC osteogenesis may facilitate the development of clinically effective engineered bone.

Stepwise differentiation of pluripotent stem cells into osteoblasts using four small molecules under serum-free and feeder-free conditions

Pluripotent stem cells are a promising tool for mechanistic studies of tissue development, drug screening, and cell-based therapies. Here, we report an effective and mass-producing strategy for the stepwise differentiation of mouse embryonic stem cells (mESCs) and mouse and human induced pluripotent stem cells (miPSCs and hiPSCs, respectively) into osteoblasts using four small molecules (CHIR99021 [CHIR], cyclopamine [Cyc], smoothened agonist [SAG], and a helioxanthin-derivative 4-(4-methoxyphenyl)pyrido[4′,3′:4,5]thieno[2,3-b]pyridine-2-carboxamide [TH]) under serum-free and feeder-free conditions. The strategy, which consists of mesoderm induction, osteoblast induction, and osteoblast maturation phases, significantly induced expressions of osteoblast-related genes and proteins in mESCs, miPSCs, and hiPSCs. In addition, when mESCs defective in runt-related transcription factor 2 (Runx2), a master regulator of osteogenesis, were cultured by the strategy, they molecularly recapitulated osteoblast phenotypes of Runx2 null mice. The present strategy will be a platform for biological and pathological studies of osteoblast development, screening of bone-augmentation drugs, and skeletal regeneration.

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Osteoblasts were differentiated from pluripotent stem cells under defined conditions

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The strategy utilizes four small molecule inducers with no serum or feeder cells

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The strategy comprises mesoderm induction and subsequent osteoblast induction

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The strategy can at least partially recapitulate physiological osteoblast development

Directed differentiation of human induced pluripotent stem cells toward bone and cartilage: in vitro versus in vivo assays

The ability to differentiate induced pluripotent stem cells (iPSCs) into committed skeletal progenitors could allow for an unlimited autologous supply of such cells for therapeutic uses; therefore, we attempted to create novel bone-forming cells from human iPSCs using lines from two distinct tissue sources and methods of differentiation that we previously devised for osteogenic differentiation of human embryonic stem cells, and as suggested by other publications. The resulting cells were assayed using in vitro methods, and the results were compared with those obtained from in vivo transplantation assays. Our results show that true bone was formed in vivo by derivatives of several iPSC lines, but that the successful cell lines and differentiation methodologies were not predicted by the results of the in vitro assays. In addition, bone was formed equally well from iPSCs originating from skin or bone marrow stromal cells (also known as bone marrow-derived mesenchymal stem cells), suggesting that the iPSCs did not retain a "memory" of their previous life. Furthermore, one of the iPSC-derived cell lines formed verifiable cartilage in vivo, which likewise was not predicted by in vitro assays.

The effect of resveratrol on normal and osteoarthritic chondrocyte metabolism

Background

Resveratrol is a polyphenolic compound commonly found in the skins of red grapes. Sirtuin 1 (SIRT1) is a human gene that is activated by resveratrol and has been shown to promote longevity and boost mitochondrial metabolism. We examined the effect of resveratrol on normal and osteoarthritic (OA) human chondrocytes.

Methods

Normal and OA chondrocytes were incubated with various concentrations of resveratrol (1 µM, 10 µM, 25 µM and 50 µM) and cultured for 24, 48 or 72 hours or for six weeks. Cell proliferation, gene expression, and senescence were evaluated.

Results

SIRT1 was significantly upregulated in normal chondrocytes with resveratrol concentrations of 25 µM and 50 µM on both two- (2D) (both p = 0.001) and three-dimensional (3D) cultures (p = 0.008 and 0.001, respectively). It was significantly upregulated in OA chondrocytes treated with 10 µM, 25 µM and 50 µM resveratrol on 2D cultures (p = 0.036, 0.002 and 0.001, respectively) and at 50 µM concentration on 3D cultures (p = 0.001). At 72 hours, the expression of collagen (COL)-10, aggrecan (AGG), and runt-related transcription factor 2 (RUNX2) was significantly greater in both 25 µM (p = 0.011, 0.006 and 0.015, respectively) and 50 µM (p = 0.019, 0.004 and 0.002, respectively) resveratrol-treated normal chondrocyte cultures. In OA chondrocytes, expression of COL10 and RUNX2 was significantly greater in 25 µM (p = 0.004 and 0.024) and 50 µM (p = 0.004 and 0.019) cultures at 72 hours on 3D cultures.

Conclusions

At concentrations of 25 µM and/or 50 µM, resveratrol treatment significantly upregulates SIRT1 gene expression in normal and osteoarthritic chondrocytes. Resveratrol induces chondrocytes into a hypertrophic state through upregulation of COL1, COL10, and RUNX2.

Cite this article: Bone Joint Res 2014;3:51–9.