Regulation of adipose-derived adult stem cells differentiating into chondrocytes with the use of rhBMP-2

Mapping theme trends and knowledge structure on adipose-derived stem cells: a bibliometric analysis from 2003 to 2017

AIM

To investigate the theme trends and knowledge structure of adipose-derived stem cells (ADSCs) related literatures by using bibliometric analysis.

MATERIALS & METHODS

Co-word analysis, strategic diagram and social network analysis were employed.

RESULTS

In line with strategic diagrams, ADSC differentiation and transplantation as main undeveloped themes in 2003-2007 were partially replaced by regeneration medicine and ADSCs for myocardial infarction in 2008 to 2012, and then partially replaced by miRNAs in ADSC genetics and nerve regeneration in 2013 to 2017. Based on social network analysis, regenerative medicine/methods, myocardial infarction/therapy, as well as miRNAs/genetics, and nerve regeneration/physiology were considered the emerging hot spots in 2008 to 2012 and 2013 to 2017.

CONCLUSION

The undeveloped themes and emerging hot spots could be considered as new research topics.

Tissue-derived scaffolds and cells for articular cartilage tissue engineering: characteristics, applications and progress

There are many factors to consider in the field of tissue engineering. For articular cartilage repair, this includes seed cells, scaffolds and chondrotrophic hormones. This review primarily focuses on the seed cells and scaffolds. Extracellular matrix proteins provide a natural scaffold for cell attachment, proliferation and differentiation. The structure and composition of tissue-derived scaffolds and native tissue are almost identical. As such, tissue-derived scaffolds hold great promise for biomedical applications. However, autologous tissue-derived scaffolds also have many drawbacks for transplantation, as harvesting autografts is limited to available donor sites and requires secondary surgery, therefore imparting additional damage to the body. This review summarizes and analyzes various cell sources and tissue-derived scaffolds applied in orthopedic tissue engineering.

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review

BACKGROUND

The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous.

SHORT CONCLUSIONS

This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place.

Adipose-Derived Stem Cells: New Treatment for Wound Healing?

Emerging evidence has shown that adipose tissue is the richest and most accessible source of mesenchymal stem cells. Many different therapies for chronic wounds exist with varying success rates. The capacity of adipose-derived stem cells (ASCs) to promote angiogenesis, secrete growth factors, regulate the inflammatory process, and differentiate into multiple cell types makes them a potential ideal therapy for chronic wounds. The aim of this article was to review all preclinical trials using ASCs in problem wound models. A systematic search was performed and 12 studies were found where different chronic wound models across different animals were treated with ASCs. Different ASC sources and delivery methods were used in the described studies. Studies demonstrated improved wound healing with utilization of ASC, and this treatment modality has so far shown great potential. However, more preclinical studies and large-scale clinical trials are needed to show if the emerging therapy can satisfy expectations.

Cartilage Regeneration of Adipose-Derived Stem Cells in the TGF-β1-Immobilized PLGA-Gelatin Scaffold

Articular cartilage has restricted self-regenerative capacity; therefore, treatment of cartilage lesions is a great challenge in the field of orthopedics. In the present study, we evaluate the enhancing effect of a transforming growth factor-beta 1 (TGF-β1)-immobilized scaffold, fabricated by incorporating TGF-β1-loaded gelatin microspheres into PLGA framework, on the differentiation of adipose-derived stem cells (ASCs) into chondrocytes. Significant increase in cell proliferation was observed in the TGF-β1-immobilized PLGA-gelatin scaffold, as compared with the ASC-seeded non-TGF-β1-immobilized PLGA-gelatin scaffold. When chondrogenic differentiation of ASCs was evaluated for both constructs, sulfated glycosaminoglycan (sGAG) content was significantly higher in the TGF-β1-immobilized scaffold. This study showed that ASCs containing the TGF-β1-immobilized scaffold better promoted cartilage regeneration in defective articular cartilage, which is assessed by histological observation. Based on the above results, we conclude that TGF-β1-immobilized PLGA-gelatin scaffold seeded with ASCs considerably enhances the quality of the tissue-engineered cartilage, therefore, advancing the field of cartilage tissue engineering.

The use of adipose stem cells in cranial facial surgery

Craniofacial malformations, have devastating psychosocial implications for many adults and children and causes huge socioeconomic burden. Currently craniofacial defects require soft tissue transfer, bone grafting techniques or difficult procedures such as microvascular free flaps. Such tissues are often limited in quantity, their harvest causes secondary large donor site defects and they lack the capability to fully restore previous form and function. Stem cell technology is being utilised for various tissue and organs of the body and consequently surgeons are eager to transfer these principles for craniofacial surgery. Adipose derived stem cells (ADSCs) are an exciting stem cell source for craniofacial surgeons due to their easy and painless isolation, relatively large abundance and familiarity with the harvesting procedure. ADSCs also have multiple desirable properties including adipogenic, osteogenic and chondrogenic potential, enhancement of angiogenesis and immunodulatory function. Due to these advantageous characteristics, ASDCs have been explored to repair craniofacial bone, soft tissue and cartilage. The desirable characteristics of ADSCs for craniofacial surgical applications will be explained. We report the experimental and clinical studies that have explored the use of ADSCs for bone, cartilage and soft tissue craniofacial defects. We conclude by establishing the key questions that are preventing the clinical application of ADSCs for craniofacial surgery.

Chondrogenesis of Human Adipose-Derived Stem Cells by In Vivo Co-graft with Auricular Chondrocytes from Microtia

OBJECTIVE

To evaluate the efficiency of chondrogenesis of human adipose-derived stem cells (ADSCs) induced by auricular chondrocytes from microtia via subcutaneous co-graft in nude mice.

METHODS

Human ADSCs and auricular chondrocytes were mixed at the ratio of 7:3 and suspended in 0.2 ml of Pluronic F-127 (5.0 × 10(7) cells/ml), and injected into Balb/c nude mice as the experimental group (Exp group). The same quantity of auricular chondrocytes (Ctr.1 group) or ADSCs (Ctr.2 group) in 0.2 ml of Pluronic F-127 was set as positive and negative control groups. The mixture of auricular chondrocytes (1.5 × 10(7) cells/ml) in 0.2 ml of Pluronic F-127 was set as the low concentration of chondrocyte control group (Ctr.3). At 8 weeks after grafting, the newly generated tissue pellets were isolated for morphological examination, haematoxylin and eosin staining, toluidine blue staining and safranin O staining of glycosaminoglycan (GAG), Masson's trichrome staining and immunohistochemical staining of type II collagen, and Verhoeff-iron-hematoxylin staining of elastic fibers. GAG content was determined by Alcian blue colorimetric method, and mRNA expression of type II collagen and aggrecan were examined by real-time PCR.

RESULTS

Cartilage-like tissue with a white translucent appearance and good elasticity was generated in the Exp and Ctr.1 groups. The tissue pellets in the Ctr.2 and Ctr.3 groups were much smaller than those in the Ctr.1 group. The mature cartilage lacunas could be observed in the Exp and Ctr.1 groups, while were rarely seen in the Ctr.3 group and not observed in the Ctr.2 group. The expression of cartilage-specific extracellular matrix such as type II collagen, GAG content, aggrecan, and elastic fibers in the Exp group was similar to that in the Ctr.1 group, whereas the expression of these extracellular matrix substances was significantly lower in the Ctr.2 and Ctr.3 groups (both P < 0.01).

CONCLUSION

Auricular chondrocytes from microtia can efficiently promote the chondrogenic differentiation and chondrogenesis of ADSCs by co-grafting in vivo.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

Human mesenchymal stem cells - current trends and future prospective

Stem cells are cells specialized cell, capable of renewing themselves through cell division and can differentiate into multi-lineage cells. These cells are categorized as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells. Mesenchymal stem cells (MSCs) are adult stem cells which can be isolated from human and animal sources. Human MSCs (hMSCs) are the non-haematopoietic, multipotent stem cells with the capacity to differentiate into mesodermal lineage such as osteocytes, adipocytes and chondrocytes as well ectodermal (neurocytes) and endodermal lineages (hepatocytes). MSCs express cell surface markers like cluster of differentiation (CD)29, CD44, CD73, CD90, CD105 and lack the expression of CD14, CD34, CD45 and HLA (human leucocyte antigen)-DR. hMSCs for the first time were reported in the bone marrow and till now they have been isolated from various tissues, including adipose tissue, amniotic fluid, endometrium, dental tissues, umbilical cord and Wharton's jelly which harbours potential MSCs. hMSCs have been cultured long-term in specific media without any severe abnormalities. Furthermore, MSCs have immunomodulatory features, secrete cytokines and immune-receptors which regulate the microenvironment in the host tissue. Multilineage potential, immunomodulation and secretion of anti-inflammatory molecules makes MSCs an effective tool in the treatment of chronic diseases. In the present review, we have highlighted recent research findings in the area of hMSCs sources, expression of cell surface markers, long-term in vitro culturing, in vitro differentiation potential, immunomodulatory features, its homing capacity, banking and cryopreservation, its application in the treatment of chronic diseases and its use in clinical trials.

Stem cells show promising results for lymphoedema treatment--a literature review

Lymphoedema is a debilitating condition, manifesting in excess lymphatic fluid and swelling of subcutaneous tissues. Lymphoedema is as of yet still an incurable condition and current treatment modalities are not satisfactory. The capacity of mesenchymal stem cells to promote angiogenesis, secrete growth factors, regulate the inflammatory process, and differentiate into multiple cell types make them a potential ideal therapy for lymphoedema. Adipose tissue is the richest and most accessible source of mesenchymal stem cells and they can be harvested, isolated, and used for therapy in a single stage procedure as an autologous treatment. The aim of this paper was to review all studies using mesenchymal stem cells for lymphoedema treatment with a special focus on the potential use of adipose-derived stem cells. A systematic search was performed and five preclinical and two clinical studies were found. Different stem cell sources and lymphoedema models were used in the described studies. Most studies showed a decrease in lymphoedema and an increased lymphangiogenesis when treated with stem cells and this treatment modality has so far shown great potential. The present studies are, however, subject to bias and more preclinical studies and large-scale high quality clinical trials are needed to show if this emerging therapy can satisfy expectations.

Cartilage tissue engineering: molecular control of chondrocyte differentiation for proper cartilage matrix reconstruction

BACKGROUND

Articular cartilage defects are a veritable therapeutic problem because therapeutic options are very scarce. Due to the poor self-regeneration capacity of cartilage, minor cartilage defects often lead to osteoarthritis. Several surgical strategies have been developed to repair damaged cartilage. Autologous chondrocyte implantation (ACI) gives encouraging results, but this cell-based therapy involves a step of chondrocyte expansion in a monolayer, which results in the loss in the differentiated phenotype. Thus, despite improvement in the quality of life for patients, reconstructed cartilage is in fact fibrocartilage. Successful ACI, according to the particular physiology of chondrocytes in vitro, requires active and phenotypically stabilized chondrocytes.

SCOPE OF REVIEW

This review describes the unique physiology of cartilage, with the factors involved in its formation, stabilization and degradation. Then, we focus on some of the most recent advances in cell therapy and tissue engineering that open up interesting perspectives for maintaining or obtaining the chondrogenic character of cells in order to treat cartilage lesions.

MAJOR CONCLUSIONS

Current research involves the use of chondrocytes or progenitor stem cells, associated with "smart" biomaterials and growth factors. Other influential factors, such as cell sources, oxygen pressure and mechanical strain are considered, as are recent developments in gene therapy to control the chondrocyte differentiation/dedifferentiation process.

GENERAL SIGNIFICANCE

This review provides new information on the mechanisms regulating the state of differentiation of chondrocytes and the chondrogenesis of mesenchymal stem cells that will lead to the development of new restorative cell therapy approaches in humans. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

BMP7 gene transfer via gold nanoparticles into stroma inhibits corneal fibrosis in vivo

This study examined the effects of BMP7 gene transfer on corneal wound healing and fibrosis inhibition in vivo using a rabbit model. Corneal haze in rabbits was produced with the excimer laser performing -9 diopters photorefractive keratectomy. BMP7 gene was introduced into rabbit keratocytes by polyethylimine-conjugated gold nanoparticles (PEI2-GNPs) transfection solution single 5-minute topical application on the eye. Corneal haze and ocular health in live animals was gauged with stereo- and slit-lamp biomicroscopy. The levels of fibrosis [α-smooth muscle actin (αSMA), F-actin and fibronectin], immune reaction (CD11b and F4/80), keratocyte apoptosis (TUNEL), calcification (alizarin red, vonKossa and osteocalcin), and delivered-BMP7 gene expression in corneal tissues were quantified with immunofluorescence, western blotting and/or real-time PCR. Human corneal fibroblasts (HCF) and in vitro experiments were used to characterize the molecular mechanism mediating BMP7’s anti-fibrosis effects. PEI2-GNPs showed substantial BMP7 gene delivery into rabbit keratocytes in vivo (2×10⁴ gene copies/ug DNA). Localized BMP7 gene therapy showed a significant corneal haze decrease (1.68±0.31 compared to 3.2±0.43 in control corneas; p<0.05) in Fantes grading scale. Immunostaining and immunoblot analyses detected significantly reduced levels of αSMA (46±5% p<0.001) and fibronectin proteins (48±5% p<0.01). TUNEL, CD11b, and F4/80 assays revealed that BMP7 gene therapy is nonimmunogenic and nontoxic for the cornea. Furthermore, alizarin red, vonKossa and osteocalcin analyses revealed that localized PEI2-GNP-mediated BMP7 gene transfer in rabbit cornea does not cause calcification or osteoblast recruitment. Immunofluorescence of BMP7-transefected HCFs showed significantly increased pSmad-1/5/8 nuclear localization (>88%; p<0.0001), and immunoblotting of BMP7-transefected HCFs grown in the presence of TGFβ demonstrated significantly enhanced pSmad-1/5/8 (95%; p<0.001) and Smad6 (53%, p<0.001), and decreased αSMA (78%; p<0.001) protein levels. These results suggest that localized BMP7 gene delivery in rabbit cornea modulates wound healing and inhibits fibrosis in vivo by counter balancing TGFβ1-mediated profibrotic Smad signaling.

Reprogramming of mouse renal tubular epithelial cells to induced pluripotent stem cells

Kidney disease has reached epidemic proportions and is associated with high mortality and morbidity rates. Stem cell-based therapy may effectively treat kidney damage by cell transplantation. The breakthrough discovery using a combination of four transcription factors to reprogram genetically somatic cells into induced pluripotent stem (iPS) cells was a milestone in stem cell therapy. The lentivirus was packaged containing OCT4, SOX2, c-MYC and KLF4 transcription factors and then transfected mouse renal tubular epithelial cells (RTECs). The colonies were picked up at 21 days and were tested by cytochemistry, immunofluorescence assay and quantitative real-time polymerase chain reaction. Viral transgene expression levels were also assessed by quantitative analysis. Additionally, embryoid bodies from iPS cells were formed, and immunofluorescence and teratoma assays were performed. Karyotype analysis of mouse RTEC-derived iPS cells was also performed. The iPS cells were indistinguishable from mouse embryonic stem cells with respect to colony morphology, the expression of pluripotency-associated transcription factors and surface markers, embryoid body-mediated differentiation potential and teratoma assays. Quantitative polymerase chain reaction demonstrated that the lentiviral transgenes were largely silenced. The mouse RTEC-derived iPS cells exhibited a normal karyotype of 40,XY. iPS cells can be produced using mouse RTECs, which would be helpful in investigations to ameliorate the symptoms of kidney disease and to slow the progression of kidney disease by in vitro and in vivo animal studies.

Osteogenic differentiation and osteochondral tissue engineering using human adipose-derived stem cells

Osteogenesis and the production of composite osteochondral tissues were investigated using human adult adipose-derived stem cells and polyglycolic acid (PGA) mesh scaffolds under dynamic culture conditions. For osteogenesis, cells were expanded with or without osteoinduction factors and cultured in control or osteogenic medium for 2 weeks. Osteogenic medium enhanced osteopontin and osteocalcin gene expression when applied after but not during cell expansion. Osteogenesis was induced and mineralized deposits were present in tissues produced using PGA culture in osteogenic medium. For development of osteochondral constructs, scaffolds seeded with stem cells were precultured in either chondrogenic or osteogenic medium, sutured together, and cultured in dual-chamber stirred bioreactors containing chondrogenic and osteogenic media in separate compartments. After 2 weeks, total collagen synthesis was 2.1-fold greater in the chondroinduced sections of the composite tissues compared with the osteoinduced sections; differentiation markers for cartilage and bone were produced in both sections of the constructs. The results from the dual-chamber bioreactor highlight the challenges associated with achieving simultaneous chondrogenic and osteogenic differentiation in tissue engineering applications using a single stem-cell source.

Influence of Different Growth Factors on Chondrogenic Differentiation of Adipose-Derived Stem Cells in Polyurethane-Fibrin Composites

Introduction

Chondrogenic differentiation of adipose-derived stem cells (ASCs) has proven to be feasible. To compensate for laryngeal palsy or cartilage defects after surgery or trauma using tissue engineering, a formable and stable scaffold material is mandatory.

Methods

ASCs were seeded in fibrin-polyurethane scaffolds and cultured in chondrogenic differentiation medium adding the growth factors TGF-□1, TGF-□3, and BMP-2 for up to 35 days.

Results

Histological examination showed acid glycosaminoglycans in the extracellular matrix in all groups. Immunofluorescence presented positive staining for collagen II, aggrecan, and SOX-9 in the TGF-□1–, TGF-□3–, and BMP-2-group. With Real-time PCR analyses, chondrogenic differentiation became apparent by the expression of the specific genes COL2A1 (collagen II), AGC 1 (aggrecan), and SOX-9, whereas collagen II expression was low in all groups compared to bone marrow-derived stem cells (BMSC) due to reduced chondrogenic ability.

Conclusions

These findings demonstrate the general ability of ASCs to differentiate into matrix-producing chondrocytes in fibrin-polyurethane scaffolds. However, further experiments are necessary to enhance this chondrogenic potential of ASCs seeded in fibrin-polyurethane scaffolds in order to produce a suitable regeneration method for treating cartilage defects or an implantable medialization material for vocal cord palsy.

Comparative review of growth factors for induction of three-dimensional in vitro chondrogenesis in human mesenchymal stem cells isolated from bone marrow and adipose tissue

The ability of bone-marrow-derived mesenchymal stem cells (MSCs) and adipose-derived stem cells (ASCs) to undergo chondrogenic differentiation has been studied extensively, and it has been suggested that the chondrogenic potential of these stem cells differ from each other. Here, we provide a comprehensive review and analysis of the various growth factor induction agents for MSC and ASC three-dimensional in vitro chondrogenic differentiation. In general, the most common growth factors for chondrogenic induction come from the transforming growth factor beta (TGFbeta) superfamily. To date, the most promising growth factors for chondrogenesis appear to be TGFbeta-3 and bone morphogenetic protein (BMP)-6. A thorough review of the literature indicates that human MSCs (hMSCs) appear to exhibit the highest chondrogenic potential in three-dimensional culture in the medium containing both dexamethasone and TGFbeta-3. Some reports indicate that the addition of BMP-6 to TFGbeta-3 and dexamethasone further increases hMSC chondrogenesis, but these results are still not consistently supported. Induction of human ASC (hASC) chondrogenesis appears most successful when dexamethasone, TGFbeta-3, and BMP-6 are used in combination. However, to date, current formulations do not always result in stable differentiation to the chondrocytic lineage by hMSCs and hASCs. Continued research must be performed to examine the expression cascades of the TFGbeta superfamily to further determine the effects of each growth factor alone and in combination on these stem cell lines.

Chondrogenesis of mesenchymal stem cells: role of tissue source and inducing factors

Multipotent mesenchymal stromal cells (MSCs) are an attractive cell source for cell therapy in cartilage. Although their therapeutic potential is clear, the requirements and conditions for effective induction of chondrogenesis in MSCs and for the production of a stable cartilaginous tissue by these cells are far from being understood. Different sources of MSCs have been considered for cartilage tissue engineering, mainly based on criteria of availability, as for adipose tissue, or of proximity to cartilage and the joint environment in vivo, as for bone marrow and synovial tissues. Focussing on human MSCs, this review will provide an overview of studies featuring comparative analysis of the chondrogenic differentiation of MSCs from different sources. In particular, it will examine the influence of the cells' origin on the requirements for the induction of chondrogenesis and on the phenotype achieved by the cells after differentiation.

A new method for cryopreserving adipose-derived stem cells: an attractive and suitable large-scale and long-term cell banking technology

Recent studies have shown potential ways for improving stem cell cryopreservation. The major need for autologous stem cell use is a long-term storage: this arises from the humans' hope of future use of their own cells. Therefore, it is important to evaluate the cell potential of vitality and differentiation before and after cryopreservation. Although several studies have shown a long-term preservation of adipose tissue, a few of them focused their attention to stem cells. The aim of this study was to evaluate the fate of cryopreserved stem cells collected from adipose tissue and stored at low a temperature in liquid nitrogen through an optimal cryopreservation solution (using slowly cooling in 6% threalose, 4% dimethyl sulfoxide, and 10% fetal bovine serum) and to develop a novel approach to efficiently preserve adipose-derived stem cells (ASCs) for future clinical applications. Results showed that stem cells, after being thawed, are still capable of differentiation and express all surface antigens detected before storage, confirming the integrity of their biology. In particular, ASCs differentiated into adipocytes, showed diffuse positivity for PPARgamma and adiponectin, and were also able to differentiate into endothelial cells without addition of angiogenic factors. Therefore, ASCs can be long-term cryopreserved, and this, due to their great numbers, is an attractive tool for clinical applications as well as of impact for the derived market.

IGF-1 and BMP-2 induces differentiation of adipose-derived mesenchymal stem cells into chondrocytes-like cells

Articular cartilage defects are common, causing significant morbidities. Tissue engineering using pluripotent stem cells is a new promising modality for cartilage repair. In the current study, we investigated the chondrogenesis of rabbit adipose-derived stem cells (ADSCs). We isolated rabbit ADSCs and transfected these cells with constructs encoding human insulin growth like factor 1 (IGF-1) and bone morphogenic protein 2 (BMP-2). We examined the growth and morphology of these transfected cells and their production of type II collagen and MMP-3. We found that IGF-1 and BMP-2 drove the chondrogenesis of ADSCs, which showed mature chondrocyte-like cells and formed cartilage nodules. These cells also produced type II collagen with a reduced production of MMP-3. Our findings suggested that human ADSCs could differentiate into chondrocyte-like cells driven by IGF-1 and BMP-2 and held promises as an abundant and ready source of stem cells for cartilage repair and regeneration.

Cartilage regeneration using adipose-derived stem cells and the controlled-released hybrid microspheres

OBJECTIVE

This study was to evaluate the effect of hybrid microspheres (MS) composed of gelatin transforming growth factor-beta (TGF-beta1)-loaded MS and chitosan MS on the enhancement of differentiation of adipose-derived stem cells (ASCs) into chondrocytes in pellet culture in vitro and the reparative capacity of pellet from ASCs and the hybrid MS-TGF used to repair cartilage defects in vivo.

METHODS

The morphology of the controlled-released MS was observed with scanning electron microscopy (SEM) and mechanical property was also tested in this study. In vitro TGF-beta1 release was evaluated by an enzyme-linked immunosorbent assay. The protein expression of Collagen II was tested by Western blot. In addition, a preliminary study on cartilage regeneration was also performed in vivo.

RESULTS

When chondrogenic differentiation of ASCs in both MS was evaluated, the protein expression of Collagen II became significantly increased for the hybrid MS-TGF, as compared with the gelatin MS-TGF. Mechanical result showed that the hybrid MS was superior to the gelatin MS. Observation of histology in vivo demonstrated that the pellet from ASCs and the hybrid MS-TGF promoted cartilage regeneration in the defects of articular cartilage much better than other groups.

CONCLUSION

Our study demonstrated that the pellet from ASCs and the hybrid MS-TGF can provide an easy and effective way to construct the tissue engineered cartilage in vitro and in vivo.

Isolation and characterization of canine umbilical cord blood-derived mesenchymal stem cells

Human umbilical cord blood-derived mesenchymal stem cells (MSCs) are known to possess the potential for multiple differentiations abilities in vitro and in vivo. In canine system, studying stem cell therapy is important, but so far, stem cells from canine were not identified and characterized. In this study, we successfully isolated and characterized MSCs from the canine umbilical cord and its fetal blood. Canine MSCs (cMSCs) were grown in medium containing low glucose DMEM with 20% FBS. The cMSCs have stem cells expression patterns which are concerned with MSCs surface markers by fluorescence- activated cell sorter analysis. The cMSCs had multipotent abilities. In the neuronal differentiation study, the cMSCs expressed the neuronal markers glial fibrillary acidic protein (GFAP), neuronal class III beta tubulin (Tuj-1), neurofilament M (NF160) in the basal culture media. After neuronal differentiation, the cMSCs expressed the neuronal markers Nestin, GFAP, Tuj-1, microtubule-associated protein 2, NF160. In the osteogenic & chondrogenic differentiation studies, cMSCs were stained with alizarin red and toluidine blue staining, respectively. With osteogenic differentiation, the cMSCs presented osteoblastic differentiation genes by RT-PCR. This finding also suggests that cMSCs might have the ability to differentiate multipotentially. It was concluded that isolated MSCs from canine cord blood have multipotential differentiation abilities. Therefore, it is suggested that cMSCs may represent a be a good model system for stem cell biology and could be useful as a therapeutic modality for canine incurable or intractable diseases, including spinal cord injuries in future regenerative medicine studies.

Cartilage Regeneration of Adipose-Derived Stem Cells in a Hybrid Scaffold from Fibrin-Modified PLGA

Adipose-derived stem cells (ASCs) appear to be a useful stem cell population, which has been shown to possess multipotentiality. The aim of this study was to evaluate the utility of ASCs in tissue-engineered cartilage using a hybrid scaffold from fibrin-modified PLGA scaffold. ASCs were isolated from rabbit adipose tissue. The PLGA scaffold was prepared by low-temperature deposition technology and the hybrid scaffold was fabricated by a freeze-drying method. When ASCs were seeded onto fibrin-modified PLGA scaffold in vitro, enhanced cellular viability was observed compared to unmodified PLGA scaffold. The analysis of proteoglycan and collagen II revealed that fibrin-modified scaffold succeeded in inducing ASCs to differentiate into chondrocytes in vitro. A preliminary study on cartilage regeneration was also performed in vivo. Observation of histology and immunoblotting demonstrated that ASCs containing the hybrid scaffold promoted cartilage regeneration in the defects of articular cartilage much better than other groups. These results indicated that ASCs containing the hybrid scaffold are a more effective way to potentially enhance articular cartilage regeneration.

Adipose-derived stem cells for soft tissue reconstruction

In soft tissue repair, there are several surgical options such as nondegradable, inert, synthetic, biodegradable implants or autologous tissue transplantation. However, the potential of using autologous adult stem cells derived from fat tissue is quickly becoming a clinical reality. The possibility of using an abundant source of extraneous tissue as a soft tissue implant has significant implications for plastic and reconstructive surgeons. This strategy would be particularly useful after tumor removal or trauma. The ability of adult stem cells derived from adipose tissue (termed adipose-derived stem cell) to proliferate and differentiate in vivo or in vitro is actively being studied owing to the potential implementation in reconstructive surgery. This review describes innovative research strategies and discusses the first clinical studies involving adipose-derived stem cells as a motif for soft tissue reconstruction.

Adipose-derived stem cells: characterization and current application in orthopaedic tissue repair

Orthopaedic tissues, such as bone, cartilage, intervertebral disc and tendon, contain cells that are difficult to culture and stimulate in vitro for repair of damaged tissue. Stem cells have the ability to self-renew and differentiate into many tissue types. Recent progress in stem cell research has led to an enthusiastic effort to utilize stem cells for orthopaedic tissue regeneration. Due to ease of harvest and abundance, adipose-derived mesenchymal cells (ASC) are an attractive, readily available adult stem cell that has become increasingly popular for use in many stem cell applications. Recent progress has been made in characterizing ASC and looking mechanistically at gene expression and cellular pathways involved in differentiation. This review focuses on (i) the characterization of ASC through expression of appropriate surface markers; (ii) modulation of in vitro differentiation of ASC through different scaffolds, growth factors, and media; and (iii) the use of ASC in orthopaedic tissue repair. Strategies for repair involve the use of differentiated or undifferentiated, fresh or passaged ASC, in conjunction with appropriate choice of media, growth factors and scaffolds. Recent in vivo studies utilizing ASC are discussed giving results on defect repair and potential for clinical orthopaedic tissue regeneration.

Chondrogenesis, bone morphogenetic protein-4 and mesenchymal stem cells

OBJECTIVE

As adult cartilage has very limited potential to regenerate, cartilage repair is challenging. Available treatments have several disadvantages, including formation of fibrocartilage instead of hyaline-like cartilage, as well as eventual ossification of the newly formed tissue. The focus of this review is the application of bone morphogenetic protein-4 (BMP-4) and mesenchymal stem cells (MSCs) in cartilage repair, a combination that could potentially lead to the formation of permanent hyaline-like cartilage in the defect.

METHODS

This review is based on recent literature in the orthopaedic and tissue engineering fields, and is focused on MCSs and bone morphogenetic proteins (BMPs).

RESULTS

BMP-4, a stimulator of chondrogenesis, both in vitro and in vivo, is a potential therapeutic agent for cartilage regeneration. BMP-4 delivery can improve the healing process of an articular cartilage defect by stimulating the synthesis of the cartilage matrix constituents: type II collagen and aggrecan. BMP-4 has also been shown to suppress chondrogenic hypertrophy and maintain regenerated cartilage. Use of an appropriate carrier for BMP-4 is crucial for successful reconstruction of cartilage defects. Due to the relatively short half-life in vivo of BMP-4, there is a need to localize and maintain the delivery of BMP-4 to the injury site. Additionally, the delivery of MSCs to the wound site could improve cartilage regeneration; therefore, the carrier should function both as a cell and a protein delivery vehicle.

CONCLUSION

The role of BMP-4 in chondrogenesis is significant, and successful methods to deliver BMP-4, with or without MSCs, to the cartilage defect site are a promising therapy to treat cartilage defects.

Bone regeneration by BMP-2 enhanced adipose stem cells loading on alginate gel

Adipose stem cells (ASCs) have the potential to differentiate into a variety of cell lineages both in vitro and in vivo. In this study, ASCs were harvested from normal Sprague-Dawley (SD) rats and transfected by BMP-2 gene before they were loaded on alginate. The ability of bone regeneration was determined in rat critical-size cranial defects. An 8-mm diameter defect was created in the calvarias of 36 rats; these rats were divided into three groups. In experimental group, the defects were filled with alginate gel combined with BMP-2 transfected ASCs; in negative control group, the defects were filled with alginate gel mixed with normal ASCs; in blank controls, the defects were filled with cell-free alginate gel. Four rats of each group were killed and the cranial defect sites were observed at 4, 8 and 16 weeks after surgery. There was complete repair of cranial defects in experimental group using the alginate gel loading BMP-2 transfected ASC, but only partial repair in negative controls and in the blank control. The engineering approach combining BMP-2 enhanced ASCs with alginate gel can therefore stimulate bone regeneration and repair for the large size bone defects.

A novel injectable scaffold for cartilage tissue engineering using adipose-derived adult stem cells

Articular cartilage has a limited self-regenerative capacity. Thus, treatment of cartilage lesions is a major challenge. Tissue engineering using a variety of biomaterials is a promising solution to the problem of cartilage damage. In this in vitro study, we investigated the effect of the presence of cartilage-tissue chondroitin-sulfate (CS) in a fibrin scaffold on the differentiation of adipose-derived adult stem cells (ADAS cells) into chondrocytes. Isolated rabbit ADAS cells were cultured in fibrin matrices with and without CS for up to 14 days. ADAS cells differentiated into chondrocytes in both matrices, but cell proliferation, glycoaminoglycans content, and type II collagen expression were significantly higher in the fibrin-CS matrices than those in the fibrin matrices alone. Histological examination and scanning electronic microscopy revealed the fibrin-CS matrices exceeded in inducing differentiation of ADAS cells into chondrocytes in terms of tissue morphological characteristics. We concluded that the fibrin-CS matrices mimicking native cartilage extracellular matrix could act as a three-dimensional scaffold for cartilage tissue engineering and have the potential for promoting ADAS cells differentiation into chondrocytes.

Differential effects of BMP-2 and TGF-beta1 on chondrogenic differentiation of adipose derived stem cells

OBJECTIVES

This article addresses the interaction of transforming growth factor beta1 (TGF-beta1) and bone morphogenic protein 2 (BMP-2) during osteo-chondrogenic differentiation of adipose-derived adult stem cells (ASC). TGF-beta1 was expected to modulate the BMP-2-induced effects through transcriptional regulation of Dlx-5, Msx-2 and Runx-2.

MATERIALS AND METHODS

Encapsulated ASC were cultured for 14 days in medium containing TGF-beta1 and/or BMP-2. mRNA expression of the extracellular matrix molecules col2a1, cartilage oligomeric matrix protein, col10a1, alkaline phosphatase (AP) and transcription factors Msx-2, Dlx-5 and Runx-2 was analysed. Release of glycosaminoglycans, collagen types II and X into the extracellular matrix was demonstrated.

RESULTS

BMP-2 and TGF-beta1 induced a chondrogenic phenotype in ASC. Combined growth factor treatment had a synergistic effect on col10a1 and an additive effect on col2a1 mRNA expression. Synthesis of glycosaminoglycans was enhanced by combined growth factor treatment. Addition of TGF-beta1 inhibited BMP-2 induced AP expression and activity and both proteins promoted chondrogenic maturation.

CONCLUSIONS

Prevention of BMP-2-induced osteogenic transdifferentiation by TGF-beta1 seemed not to be mediated by transcriptional regulation of Dlx-5. Due to these findings, simultaneous stimulation of ASC with BMP-2 and TGF-beta1 seemed to be beneficial for complete differentiation of ASC into chondrocytes.

Chondrocyte outgrowth into a gelatin scaffold in a single impact load model of damage/repair - effect of BMP-2

Background

Articular cartilage has little capacity for repair in vivo, however, a small number of studies have shown that, in vitro, a damage/repair response can be induced. Recent work by our group has shown that cartilage can respond to single impact load and culture by producing repair cells on the articular surface. The purpose of this study was to identify whether chondrocyte outgrowth into a 3D scaffold could be observed following single impact load and culture. The effect of bone morphogenic-2 (BMP-2) on this process was investigated.

Methods

Cartilage explants were single impact loaded, placed within a scaffold and cultured for up to 20 days +/- BMP-2. Cell numbers in the scaffold, on and extruding from the articular surface were quantified and the immunohistochemistry used to identify the cellular phenotype.

Results

Following single impact load and culture, chondrocytes were observed in a 3D gelatin scaffold under all culture conditions. Chondrocytes were also observed on the articular surface of the cartilage and extruding out of the parent cartilage and on to the cartilage surface. BMP-2 was demonstrated to quantitatively inhibit these events.

Conclusion

These studies demonstrate that articular chondrocytes can be stimulated to migrate out of parent cartilage following single impact load and culture. The addition of BMP-2 to the culture medium quantitatively reduced the repair response. It may be that the inhibitory effect of BMP-2 in this experimental model provides a clue to the apparent inability of articular cartilage to heal itself following damage in vivo.

Adipose-derived stem cells and chondrogenesis

Cartilage has only a very limited capacity to renew its original structure. Stem cells have been used to repair damaged cartilage, and recent studies have indicated that stem cells from adipose tissue are attractive cell sources that have the capacity of multipotentiality to differentiate into osteogenic, chondrogenic, myogenic, neurogenic and endothelial cells. Adipose-derived stem cells (ASC) have unique characteristics compared with stem cells from BM. At present, ASC have been studied to promote chondrogenesis. This review discusses the application of ASC to cartilage formation.