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1.  scAAV-Mediated Gene Transfer of Interleukin 1-Receptor Antagonist to Synovium and Articular Cartilage in Large Mammalian Joints 
Gene therapy  2012;20(6):670-677.
With the long-term goal of developing a gene-based treatment for osteoarthritis (OA), we performed studies to evaluate the equine joint as a model for AAV-mediated gene transfer to large, weight-bearing human joints. A self-complementary AAV2 vector containing the coding regions for human interleukin-1 receptor antagonist (hIL-1Ra) or green fluorescent protein (GFP) was packaged in AAV capsid serotypes 1, 2, 5, 8 and 9. Following infection of human and equine synovial fibroblasts in culture, we found that both were only receptive to transduction with AAV1, 2 and 5. For these serotypes, however, transgene expression from the equine cells was consistently at least 10-fold higher. Analyses of AAV surface receptor molecules and intracellular trafficking of vector genomes implicate enhanced viral uptake by the equine cells. Following delivery of 1 × 1011 vector genomes of serotypes 2, 5 and 8 into the forelimb joints of the horse, all three enabled hIL-1Ra expression at biologically relevant levels and effectively transduced the same cell types, primarily synovial fibroblasts and, to a lesser degree, chondrocytes in articular cartilage. These results provide optimism that AAV vectors can be effectively adapted for gene delivery to large human joints affected by OA.
PMCID: PMC3577988  PMID: 23151520
Osteoarthritis; Self-complementary Adeno-Associated Virus; Interleukin-1 Receptor Antagonist; Synovium; Cartilage; Equine
2.  Perspectives on the Use of Gene Therapy for Chronic Joint Diseases 
Current gene therapy  2008;8(4):273-286.
Advances in molecular and cellular biology have identified a wide variety of proteins including targeted cytokine inhibitors, immunomodulatory proteins, cytotoxic mediators, angiogenesis inhibitors, and intracellular signalling molecules that could be of great benefit in the treatment of chronic joint diseases, such as osteo- and rheumatoid arthritis. Unfortunately, protein-based drugs are difficult to administer effectively. They have a high rate of turnover, requiring frequent readministration, and exposure in non-diseased tissue can lead to serious side effects. Gene transfer technologies offer methods to enhance the efficacy of protein-based therapies, enabling the body to produce these molecules locally at elevated levels for extended periods. The proof of concept of gene therapies for arthritis has been exhaustively demonstrated in multiple laboratories and in numerous animal models. This review attempts to condense these studies and to discuss the relative benefits and limitations of the methods proposed and to discuss the challenges toward translating these technologies into clinical realities.
PMCID: PMC4350777  PMID: 18691023
Arthritis; gene therapy; adenovirus; adeno-associated virus; lentivirus; osteoarthritis; interleukin-1; tumor necrosis factor
3.  Animal Models in Osteosarcoma 
Frontiers in Oncology  2014;4:189.
Osteosarcoma (OS) is the most common non-hematologic primary tumor of bone in children and adults. High-dose cytotoxic chemotherapy and surgical resection have improved prognosis, with long-term survival for non-metastatic disease approaching 70%. However, most OS tumors are high grade and tend to rapidly develop pulmonary metastases. Despite clinical advances, patients with metastatic disease or relapse have a poor prognosis. Toward a better understanding of the molecular pathogenesis of human OS, several genetically modified OS mouse models have been developed and will be reviewed here. However, better animal models that more accurately recapitulate the natural progression of the disease are needed for the development of improved prognostic and diagnostic markers as well as targeted therapies for both primary and metastatic OS.
PMCID: PMC4102850  PMID: 25101245
osteosarcoma; conditional mouse models; germ-line mouse models; animal models; p53; RB
4.  Gene delivery of TGF-β1 induces arthrofibrosis and chondrometaplasia of synovium in vivo 
To understand the cellular and molecular events contributing to arthrofibrosis, we used an adenovirus to deliver and overexpress transforming growth factor-beta 1 (TGF-β1) cDNA (Ad.TGF-β1) in the knee joints of immunocompromised rats. Following delivery, animals were killed periodically, and joint tissues were examined macroscopically and histologically. PCR-array was used to assay alterations in expression patterns of extracellular matrix (ECM)-associated genes. By days 5 and 10, TGF-β1 induced an increase in knee diameter and complete encasement of joints in dense scar-like tissue, locking joints at 90° of flexion. Histologically, massive proliferation of synovial fibroblasts was seen, followed by their differentiation into myofibroblasts. The fibrotic tissue displaced the normal architecture of the joint capsule and fused with articular cartilage. RNA expression profiles showed high levels of transcription of numerous MMPs, matricellular and ECM proteins. By day 30, the phenotype of the fibrotic tissue had undergone chondrometaplasia, indicated by cellular morphology, matrix composition and >100-fold increases in expression of collagen type II and cartilage link protein. Pre-labeling of articular cells by injection with recombinant lentivirus containing eGFP cDNA showed fibrotic/cartilaginous tissues appeared to arise almost entirely from local proliferation and differentiation of resident fibroblasts. Altogether, these results indicate that TGF-β1 is a potent inducer of arthrofibrosis, and illustrate the proliferative potential and plasticity of articular fibroblasts. They suggest the mechanisms causing arthrofibrosis share many aspects with tumorigenesis.
PMCID: PMC3724510  PMID: 20697373
adhesive capsulitis; arthrofibrosis; chondrometaplasia; differentiation; frozen shoulder; synovium; transforming growth factor-beta 1
5.  Getting arthritis gene therapy into the clinic 
Nature reviews. Rheumatology  2010;7(4):244-249.
Gene transfer technologies enable the controlled, targeted and sustained expression of gene products at precise anatomical locations, such as the joint. In this way, they offer the potential for more-effective, less-expensive treatments of joint diseases with fewer extra-articular adverse effects. A large body of preclinical data confirms the utility of intra-articular gene therapy in animal models of rheumatoid arthritis and osteoarthritis. However, relatively few clinical trials have been conducted, only one of which has completed phase II. This article summarizes the status in 2010 of the clinical development of gene therapy for arthritis, identifies certain constraints to progress and suggests possible solutions.
PMCID: PMC3460537  PMID: 21135882
6.  Indian hedgehog gene transfer is a chondrogenic inducer of human mesenchymal stem cells 
Arthritis Research & Therapy  2012;14(4):R168.
To date, no single most-appropriate factor or delivery method has been identified for the purpose of mesenchymal stem cell (MSC)-based treatment of cartilage injury. Therefore, in this study we tested whether gene delivery of the growth factor Indian hedgehog (IHH) was able to induce chondrogenesis in human primary MSCs, and whether it was possible by such an approach to modulate the appearance of chondrogenic hypertrophy in pellet cultures in vitro.
First-generation adenoviral vectors encoding the cDNA of the human IHH gene were created by cre-lox recombination and used alone or in combination with adenoviral vectors, bone morphogenetic protein-2 (Ad.BMP-2), or transforming growth factor beta-1 (Ad.TGF-β1) to transduce human bone-marrow derived MSCs at 5 × 102 infectious particles/cell. Thereafter, 3 × 105 cells were seeded into aggregates and cultured for 3 weeks in serum-free medium, with untransduced or marker gene transduced cultures as controls. Transgene expressions were determined by ELISA, and aggregates were analysed histologically, immunohistochemically, biochemically and by RT-PCR for chondrogenesis and hypertrophy.
IHH, TGF-β1 and BMP-2 genes were equipotent inducers of chondrogenesis in primary MSCs, as evidenced by strong staining for proteoglycans, collagen type II, increased levels of glycosaminoglycan synthesis, and expression of mRNAs associated with chondrogenesis. IHH-modified aggregates, alone or in combination, also showed a tendency to progress towards hypertrophy, as judged by the expression of alkaline phosphatase and stainings for collagen type X and Annexin 5.
As this study provides evidence for chondrogenic induction of MSC aggregates in vitro via IHH gene delivery, this technology may be efficiently employed for generating cartilaginous repair tissues in vivo.
PMCID: PMC3580562  PMID: 22817660
7.  Evidence for the osteosarcoma stem cell 
Current orthopaedic practice  2011;22(4):322-326.
Osteosarcoma is a highly malignant bone tumor of children and young adults. Cytotoxic chemotherapy combined with aggressive surgery only has a 60% survival rate. Historically, chemotherapy has been developed assuming that all cells within a particular cancer are clonal and near identical. Appreciating the now apparent functional heterogeneity of osteosarcoma cells within and between individual tumors will likely be critical in developing much needed novel effective therapies. The foundation for this heterogeneity may lie in the so called “cancer stem cell” or tumorigenic cell of origin. In this brief review, we will examine the evidence for the existence of this cell and its potential importance for future therapies.
PMCID: PMC3132515  PMID: 21755019
8.  An acidic oligopeptide displayed on AAV2 improves axial muscle tropism after systemic delivery 
The appropriate tropism of adeno-associated virus (AAV) vectors that are systemically injected is crucial for successful gene therapy when local injection is not practical. Acidic oligopeptides have been shown to enhance drug delivery to bones.
In this study six-L aspartic acids (D6) were inserted into the AAV2 capsid protein sequence between amino acid residues 587 and 588. 129SVE mice were injected with double-stranded wild-type- (WT-) or D6-AAV2 mCherry expression vectors (3.24 x 1010 vg per animal) via the superficial temporal vein within 24 hours of birth.
Fluorescence microscopy and quantitative polymerase chain reaction confirmed higher levels of mCherry expression in the paraspinal and gluteus muscles in the D6-AAV2 injected mice. The results revealed that although D6-AAV2 was less efficient in the transduction of immortalized cells stronger mCherry signals were detected over the spine and pelvis by live imaging in the D6-AAV2-injected mice than were detected in the WT-AAV2-injected mice. In addition, D6-AAV2 lost the liver tropism observed for WT-AAV2.
An acidic oligopeptide displayed on AAV2 improves axial muscle tropism and decreases liver tropism after systemic delivery. This modification should be useful in creating AAV vectors that are suitable for gene therapy for diseases involving the proximal muscles.
PMCID: PMC3416570  PMID: 22709483
Adeno-associated virus; Tropism; L-aspartic acid; Acidic oligopeptide
9.  Expression of an Exogenous Human Oct-4 Promoter Identifies Tumor-Initiating Cells in Osteosarcoma 
Cancer research  2009;69(14):5648-5655.
We explored the nature of the tumor-initiating cell in osteosarcoma, a bone malignancy that predominately occurs in children. Previously we observed expression of Oct-4, an embryonal transcriptional regulator, in osteosarcoma cell cultures and tissues. To examine the relationship between Oct-4 and tumorigenesis, cells from an osteosarcoma biopsy (OS521) were stably transfected with a plasmid containing the human Oct-4 promoter driving a GFP reporter, to generate the transgenic line OS521Oct-4p. In culture, only ∼24% of the OS521Oct-4p cells were capable of activating the transgenic Oct-4 promoter; yet, xenograft tumors generated in NOD/SCID mice contained approximately 67% GFP+ cells, which selectively expressed the MSC-associated surface antigens CD105 and ICAM-1. Comparison of the tumor-forming capacity of GFP-enriched and GFP-depleted cell fractions revealed that the GFP-enriched fractions were at least 100-fold more tumorigenic, capable of forming tumors at doses of less than 300 cells, and formed metastases in the lung. Clonal populations derived from a single Oct-4/GFP+ cell were capable of forming tumors heterogeneous for Oct-4/GFP expression. These data are consistent with the cancer stem cell model of tumorigenesis in osteosarcoma and implicate a functional link between the capacity to activate an exogenous Oct-4 promoter and tumor formation. This osteosarcoma tumor-initiating cell appears highly prolific and constitutes a majority of the cell population in a primary xenograft tumor, which may provide a biological basis for the particular virulence of this type of cancer.
PMCID: PMC2841219  PMID: 19584295
Oct-4; Osteosarcoma; Cancer Stem Cell; Embryonic Stem Cell; Tumorigenicity
10.  Intra-articular gene delivery and expression of interleukin-1Ra mediated by self-complementary adeno-associated virus 
The journal of gene medicine  2009;11(7):605-614.
The adeno-associated virus (AAV) has many safety features that favor its use in the treatment of arthritic conditions; however, the conventional, single-stranded vector is inefficient for gene delivery to fibroblastic cells that primarily populate articular tissues. This has been attributed to the inability of these cells to convert the vector to a double-stranded form. To overcome this, we evaluated double-stranded self-complementary (sc) AAV as a vehicle for intra-articular gene delivery.
Conventional and scAAV vectors were used to infect lapine articular fibroblasts in culture to determine transduction efficiency, transgene expression levels, and nuclear trafficking. scAAV containing the cDNA for interleukin (IL)-1 receptor antagonist (Ra) was delivered to the joints of naïve rabbits and those with IL-1β-induced arthritis. From lavage of the joint space, levels of transgenic expression and persistence were measured by enzyme-linked immunosorbent assay. Infiltrating leukocytes were quantified using a hemocytometer.
Transgene expression from scAAV had an earlier onset and was approximately 25-fold greater than conventional AAV despite the presence of similar numbers of viral genomes in the nuclei of infected cells. Fibroblasts transduced with scAAV produced amounts of IL1-Ra comparable to those transduced with adenoviral and lentiviral vectors. IL1-Ra was present in lavage fluid of most animals for 2 weeks in sufficient quantities to inhibit inflammation of the IL-1β-driven model. Once lost, neither subsequent inflammatory events, nor re-administration of the virus could re-establish transgene expression.
scAAV-mediated intra-articular gene transfer is robust and similarly efficient in both normal and inflamed joints; the resulting transgenic expression is sufficient to achieve biological relevance in joints of human proportion.
PMCID: PMC2876984  PMID: 19384892
adeno-associated virus; arthritis; gene therapy; interleukin-1; interleukin-1 receptor antagonist
11.  Enhanced In Vitro Chondrogenesis of Primary Mesenchymal Stem Cells by Combined Gene Transfer 
Tissue Engineering. Part A  2008;15(5):1127-1139.
Because articular cartilage has a poor regeneration capacity, numerous cell-based approaches to therapy are currently being explored. The present study involved the use of gene transfer as a means to provide sustained delivery of chondrogenic proteins to primary mesenchymal stem cells (MSCs). In previous work, we found that adenoviral-mediated gene transfer of transforming growth factor-beta1 (TGF-β1) and bone morphogenetic protein 2 (BMP-2), but not insulin-like growth factor 1 (IGF-1), could be used to induce chondrogenic differentiation of MSCs in an aggregate culture system. In the present study, we examined the effects on chondrogenesis of these transgenes when delivered in combination. Cultures of bone marrow–derived MSCs were infected with 2.5 × 102 or 2.5 × 103 viral particles/cell of each adenoviral vector individually, or in combination, seeded into aggregates, and cultured for 3 weeks in a defined serum-free medium. Levels of transgene product in the medium were initially high, approximately 100 ng/mL TGF-β1, 120 ng/mL BMP-2, and 80 ng/mL IGF-1 at day 3, and declined thereafter. We found that co-expression of IGF-1 and TGF-β1, BMP-2, or both at low doses resulted in larger aggregates, higher levels of glycosaminoglycan synthesis, stronger staining for proteoglycans and collagen type II and X, and greater expression of cartilage-specific marker genes than with either transgene alone. Gene-induced chondrogenesis of MSCs using multiple genes that act synergistically may enable the administration of reduced viral doses in vivo and could be of considerable benefit for the development of cell-based therapies for cartilage repair.
PMCID: PMC2810414  PMID: 18826340
12.  Clinical Responses to Gene Therapy in Joints of Two Subjects with Rheumatoid Arthritis 
Human Gene Therapy  2009;20(2):97-101.
This paper provides the first evidence of a clinical response to gene therapy in human arthritis. Two subjects with rheumatoid arthritis received ex vivo, intraarticular delivery of human interleukin-1 receptor antagonist (IL-1Ra) cDNA. To achieve this, autologous synovial fibroblasts were transduced with a retrovirus, MFG-IRAP, carrying IL-1Ra as the transgene, or remained as untransduced controls. Symptomatic metacarpophalangeal (MCP) joints were injected with control or transduced cells. Joints were clinically evaluated on the basis of pain; the circumference of MCP joint 1 was also measured. After 4 weeks, joints underwent surgical synovectomy. There were no adverse events in either subject. The first subject responded dramatically to gene transfer, with a marked and rapid reduction in pain and swelling that lasted for the entire 4 weeks of the study. Remarkably, joints receiving IL-1Ra cDNA were protected from flares that occurred during the study period. Analysis of RNA recovered after synovectomy revealed enhanced expression of IL-1Ra and reduced expression of matrix metalloproteinase-3 and IL-1β. The second subject also responded with reduced pain and swelling. Thus, gene transfer to human, rheumatoid joints can be accomplished safely to produce clinical benefit, at least in the short term. Using this ex vivo procedure, the transgene persisted within the joint for at least 1 month. Further clinical studies are warranted.
PMCID: PMC2855248  PMID: 18986219
13.  Hypertrophy is induced during the in vitro chondrogenic differentiation of human mesenchymal stem cells by bone morphogenetic protein-2 and bone morphogenetic protein-4 gene transfer 
Arthritis Research & Therapy  2009;11(5):R148.
The present study compares bone morphogenetic protein (BMP)-4 and BMP-2 gene transfer as agents of chondrogenesis and hypertrophy in human primary mesenchymal stem cells (MSCs) maintained as pellet cultures.
Adenoviral vectors carrying cDNA encoding human BMP-4 (Ad.BMP-4) were constructed by cre-lox combination and compared to previously generated adenoviral vectors for BMP-2 (Ad.BMP-2), green fluorescent protein (Ad.GFP), or firefly luciferase (Ad.Luc). Cultures of human bone-marrow derived MSCs were infected with 5 × 102 viral particles/cell of Ad.BMP-2, or Ad.BMP-4, seeded into aggregates and cultured for three weeks in a defined, serum-free medium. Untransduced cells or cultures transduced with marker genes served as controls. Expression of BMP-2 and BMP-4 was determined by ELISA, and aggregates were analyzed histologically, immunohistochemically, biochemically and by RT-PCR for chondrogenesis and hypertrophy.
Levels of BMP-2 and BMP-4 in the media were initially 30 to 60 ng/mL and declined thereafter. BMP-4 and BMP-2 genes were equipotent inducers of chondrogenesis in primary MSCs as judged by lacuna formation, strong staining for proteoglycans and collagen type II, increased levels of GAG synthesis, and expression of mRNAs associated with the chondrocyte phenotype. However, BMP-4 modified aggregates showed a lower tendency to progress towards hypertrophy, as judged by expression of alkaline phosphatase, annexin 5, immunohistochemical staining for type X collagen protein, and lacunar size.
BMP-2 and BMP-4 were equally effective in provoking chondrogenesis by primary human MSCs in pellet culture. However, chondrogenesis triggered by BMP-2 and BMP-4 gene transfer showed considerable evidence of hypertrophic differentiation, with, the cells resembling growth plate chondrocytes both morphologically and functionally. This suggests caution when using these candidate genes in cartilage repair.
PMCID: PMC2787261  PMID: 19799789
14.  Gene therapy of the rheumatic diseases: 1998 to 2008 
During the decade since the launch of Arthritis Research, the application of gene therapy to the rheumatic diseases has experienced the same vicissitudes as the field of gene therapy as a whole. There have been conceptual and technological advances and an increase in the number of clinical trials. However, funding has been unreliable and a small number of high-profile deaths in human trials, including one in an arthritis gene therapy trial, have provided ammunition to skeptics. Nevertheless, steady progress has been made in a number of applications, including rheumatoid arthritis and osteoarthritis, Sjögren syndrome, and lupus. Clinical trials in rheumatoid arthritis have progressed to phase II and have provided the first glimpses of possible efficacy. Two phase I protocols for osteoarthritis are under way. Proof of principle has been demonstrated in animal models of Sjögren syndrome and lupus. For certain indications, the major technological barriers to the development of genetic therapies seem to have been largely overcome. The translational research necessary to turn these advances into effective genetic medicines requires sustained funding and continuity of effort.
PMCID: PMC2688220  PMID: 19232068
15.  Reduction in Severity of a Herpes Simplex Virus Type 1 Murine Infection by Treatment with a Ribozyme Targeting the UL20 Gene RNA▿  
Journal of Virology  2008;82(15):7467-7474.
Hammerhead ribozymes were designed to target mRNA of several essential herpes simplex virus type 1 (HSV-1) genes. A ribozyme specific for the late gene UL20 was packaged in an adenovirus vector (Ad-UL20 Rz) and evaluated for its capacity to inhibit the viral replication of several HSV-1 strains, including that of the wild-type HSV-1 (17syn+ and KOS) and several acycloguanosine-resistant strains (PAAr5, tkLTRZ1, and ACGr4) in tissue culture. The Ad-UL20 Rz was also tested for its ability to block an HSV-1 infection, using the mouse footpad model. Mouse footpads were treated with either the Ad-UL20 Rz or an adenoviral vector expressing green fluorescent protein (Ad-GFP) and then infected immediately thereafter with 104 PFU of HSV-1 strain 17syn+. Ad-UL20 ribozyme treatment consistently led to a 90% rate of protection for mice from lethal HSV-1 infection, while the survival rate in the control groups was less than 45%. Consistent with this protective effect, treatment with the Ad-UL20 Rz reduced the viral DNA load in the feet, the dorsal root ganglia, and the spinal cord relative to that of the Ad-GFP-treated animals. This study suggests that ribozymes targeting essential genes of the late kinetic class may represent a new therapeutic strategy for inhibiting HSV infection.
PMCID: PMC2493317  PMID: 18508896
16.  Arthritis gene therapy's first death 
In July 2007 a subject died while enrolled in an arthritis gene therapy trial. The study was placed on clinical hold while the circumstances surrounding this tragedy were investigated. Early in December 2007 the Food and Drug Administration removed the clinical hold, allowing the study to resume with minor changes to the protocol. In the present article we collate the information we were able to obtain about this clinical trial and discuss it in the wider context of arthritis gene therapy.
PMCID: PMC2483436  PMID: 18510784
17.  Major biological obstacles for persistent cell-based regeneration of articular cartilage 
Hyaline articular cartilage, the load-bearing tissue of the joint, has very limited repair and regeneration capacities. The lack of efficient treatment modalities for large chondral defects has motivated attempts to engineer cartilage constructs in vitro by combining cells, scaffold materials and environmental factors, including growth factors, signaling molecules, and physical influences. Despite promising experimental approaches, however, none of the current cartilage repair strategies has generated long lasting hyaline cartilage replacement tissue that meets the functional demands placed upon this tissue in vivo. The reasons for this are diverse and can ultimately result in matrix degradation, differentiation or integration insufficiencies, or loss of the transplanted cells and tissues. This article aims to systematically review the different causes that lead to these impairments, including the lack of appropriate differentiation factors, hypertrophy, senescence, apoptosis, necrosis, inflammation, and mechanical stress. The current conceptual basis of the major biological obstacles for persistent cell-based regeneration of articular cartilage is discussed, as well as future trends to overcome these limitations.
PMCID: PMC2206353  PMID: 17561986
18.  Exogenous glucosamine globally protects chondrocytes from the arthritogenic effects of IL-1β 
The effects of exogenous glucosamine on the biology of articular chondrocytes were determined by examining global transcription patterns under normal culture conditions and following challenge with IL-1β. Chondrocytes isolated from the cartilage of rats were cultured in several flasks either alone or in the presence of 20 mM glucosamine. Six hours later, one-half of the cultures of each group were challenged with 10 ng/ml IL-1β. Fourteen hours after this challenge, RNA was extracted from each culture individually and used to probe microarray chips corresponding to the entire rat genome. Glucosamine alone had no observable stimulatory effect on the transcription of primary cartilage matrix genes, such as aggrecan, collagen type II, or genes involved in glycosaminoglycan synthesis; however, glucosamine proved to be a potent, broad-spectrum inhibitor of IL-1β. Of the 2,813 genes whose transcription was altered by IL-1β stimulation (P < 0.0001), glucosamine significantly blocked the response in 2,055 (~73%). Glucosamine fully protected the chondrocytes from IL-1-induced expression of inflammatory cytokines, chemokines, and growth factors as well as proteins involved in prostaglandin E2 and nitric oxide synthesis. It also blocked the IL-1-induced expression of matrix-specific proteases such as MMP-3, MMP-9, MMP-10, MMP-12, and ADAMTS-1. The concentrations of IL-1 and glucosamine used in these assays were supraphysiological and were not representative of the arthritic joint following oral consumption of glucosamine. They suggest, however, that the potential benefit of glucosamine in osteoarthritis is not related to cartilage matrix biosynthesis, but is more probably related to its ability to globally inhibit the deleterious effects of IL-1β signaling. These results suggest that glucosamine, if administered effectively, may indeed have anti-arthritic properties, but primarily as an anti-inflammatory agent.
PMCID: PMC1794517  PMID: 17109745
19.  Stem-Like Cells in Bone Sarcomas: Implications for Tumorigenesis1 
Neoplasia (New York, N.Y.)  2005;7(11):967-976.
Bone sarcomas are a clinically and molecularly heterogeneous group of malignancies characterized by varying degrees of mesenchymal differentiation. Despite advances in medical and surgical management, survival rates for high-grade tumors have remained static at 50% to 70%. Tumor stem cells have been recently implicated in the pathogenesis of other heterogeneous, highly malignant tumors. We demonstrate here the existence of a small subpopulation of self-renewing bone sarcoma cells that are capable of forming suspended spherical, clonal colonies, also called “sarcospheres,” in anchorage-independent, serum-starved conditions. These bone sarcoma cells as well as tissue specimens express activated STAT3 and the marker genes of pluripotent embryonic stem (ES) cells, Oct 3/4 and Nanog. Expression levels of Oct 3/4 and Nanog are greater in sarcospheres than in adherent cultures. A subset of bone sarcoma cells displays several surface markers of mesenchymal stem cells (Stro-1, CD105, and CD44) as well as attributes of mesodermal, ectodermal, and endodermal differentiation. Although previously documented in brain and breast tumors, our results support the extension of the cancer stem cell hypothesis to include tumors of mesenchymal lineage. Furthermore, they suggest the participation of ES cell homeobox proteins in non–germ cell tumorigenesis.
PMCID: PMC1502023  PMID: 16331882
Sarcoma; Stro-1; self-renewal; pluripotent Oct 3/4; Nanog
20.  The 3rd International Meeting on Gene Therapy in Rheumatology and Orthopaedics 
Arthritis Research & Therapy  2005;7(6):273-278.
The 3rd International Meeting on Gene Therapy in Rheumatology and Orthopaedics was held in Boston, Massachusetts, USA in May 2004. Keystone lectures delivered by Drs Joseph Glorioso and Inder Verma provided comprehensive, up-to-date information on all major virus vectors. Other invited speakers covered the application of gene therapy to treatment of arthritis, including the latest clinical trial in rheumatoid arthritis, as well as lupus and Sjögren's syndrome. Applications in mesenchymal stem cell biology, tissue repair, and regenerative medicine were also addressed. The field has advanced considerably since the previous meeting in this series, and further clinical trials seem likely.
PMCID: PMC1297596  PMID: 16277703
21.  A comparative study of the inhibitory effects of interleukin-1 receptor antagonist following administration as a recombinant protein or by gene transfer 
Arthritis Research & Therapy  2003;5(5):R301-R309.
Anakinra, the recombinant form of IL-1 receptor antagonist (IL-1Ra), has been approved for clinical use in the treatment of rheumatoid arthritis as the drug Kineret™, but it must be administered daily by subcutaneous injection. Gene transfer may offer a more effective means of delivery. In this study, using prostaglandin E2 production as a measure of stimulation, we quantitatively compared the ability of anakinra, as well as that of IL-1Ra delivered by gene transfer, to inhibit the biologic actions of IL-1β. Human synovial fibroblast cultures were incubated with a range of doses of anakinra or HIG-82 cells genetically modified to constitutively express IL-1Ra. The cultures were then challenged with recombinant human IL-1β either simultaneously with addition of the source of IL-1Ra or 24 hours later. In a similar manner, the potencies of the two sources of IL-1Ra were compared when human synovial fibroblasts were challenged with IL-1β produced constitutively by genetically modified cells. No significant difference in inhibitory activity was observed between recombinant protein and IL-1Ra provided by the genetically modified cells, under static culture conditions, even following incubation for 4 days. However, under culture conditions that provided progressive dilution of the culture media, striking differences between these methods of protein delivery became readily apparent. Constitutive synthesis of IL-1Ra by the genetically modified cells provided sustained or increased protection from IL-1 stimulation over time, whereas the recombinant protein became progressively less effective. This was particularly evident under conditions of continuous IL-1β synthesis.
PMCID: PMC193732  PMID: 12932294
arthritis; gene therapy; IL-1; IL-1 receptor antagonist; synoviocytes
22.  Adverse effects of adenovirus-mediated gene transfer of human transforming growth factor beta 1 into rabbit knees 
Arthritis Research & Therapy  2003;5(3):R132-R139.
To examine the effect of transforming growth factor (TGF)-β1 on the regulation of cartilage synthesis and other articular pathologies, we used adenovirus-mediated intra-articular gene transfer of TGF-β1 to both naïve and arthritic rabbit knee joints. Increasing doses of adenoviral vector expressing TGF-β1 were injected into normal and antigen-induced arthritis rabbit knee joints through the patellar tendon, with the same doses of an adenoviral vector expressing luciferase injected into the contralateral knees as the control. Intra-articular injection of adenoviral vector expressing TGF-β1 into the rabbit knee resulted in dose-dependent TGF-β1 expression in the synovial fluid. Intra-articular TGF-β1 expression in both naïve and arthritic rabbit knee joints resulted in significant pathological changes in the rabbit knee as well as in adjacent muscle tissue. The observed changes induced by elevated TGF-β1 included inhibition of white blood cell infiltration, stimulation of glycosaminoglycan release and nitric oxide production, and induction of fibrogenesis and muscle edema. In addition, induction of chondrogenesis within the synovial lining was observed. These results suggest that even though TGF-β1 may have anti-inflammatory properties, it is unable to stimulate repair of damaged cartilage, even stimulating cartilage degradation. Gene transfer of TGF-β1 to the synovium is thus not suitable for treating intra-articular pathologies.
PMCID: PMC165041  PMID: 12723985
arthritis gene therapy; cartilage degradation; inflammatory; nitric oxide; rabbit model; transforming growth factor-β1
23.  Future of adenoviruses in the gene therapy of arthritis 
Arthritis Research  2001;3(3):142-146.
Recombinant adenoviruses are straightforward to produce at high titres, have a promiscuous host-range, and, because of their ability to infect nondividing cells, lend themselves to in vivo gene delivery. Such advantages have led to their widespread and successful use in preclinical studies of arthritis gene therapy. While adenoviral vectors are well suited to 'proof of principle' experiments in laboratory animals, there are several barriers to their use in human studies at this time. Transient transgene expression limits their application to strategies, such as synovial ablation, which do not require extended periods of gene expression. Moreover, there are strong immunological barriers to repeat dosing. In addition, safety concerns predicate local, rather than systemic, delivery of the virus. Continued engineering of the adenoviral genome is producing vectors with improved properties, which may eventually overcome these issues. Promising avenues include the development of 'gutted' vectors encoding no endogenous viral genes and of adenovirus–AAV chimeras. Whether these will offer advantages over existing vectors, which may already provide safe, long-term gene expression following in vivo delivery, remains to be seen.
PMCID: PMC128890  PMID: 11299054
gene expression; gene therapy; immunity; vector; virus
24.  Gene therapy for established murine collagen-induced arthritis by local and systemic adenovirus-mediated delivery of interleukin-4 
Arthritis Research  2000;2(4):293-302.
To determine whether IL-4 is therapeutic in treating established experimental arthritis, a recombinant adenovirus carrying the gene that encodes murine IL-4 (Ad-mIL-4) was used for periarticular injection into the ankle joints into mice with established collagen-induced arthritis (CIA). Periarticular injection of Ad-mIL-4 resulted in a reduction in the severity of arthritis and joint swelling compared with saline- and adenoviral control groups. Local expression of IL-4 also reduced macroscopic signs of joint inflammation and bone erosion. Moreover, injection of Ad-mIL-4 into the hind ankle joints resulted in a decrease in disease severity in the untreated front paws. Systemic delivery of murine IL-4 by intravenous injection of Ad-mIL-4 resulted in a significant reduction in the severity of early-stage arthritis.
Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease that is characterized by joint inflammation, and progressive cartilage and bone erosion. Recent research has identified certain biologic agents that appear more able than conventional therapies to halt effectively the progression of disease, as well as ameliorate disease symptoms. One potential problem with the use of biologic agents for arthritis therapy is the need for daily or weekly repeat dosing. The transfer of genes directly to the synovial lining can theoretically circumvent the need for repeat dosing and reduce potential systemic side effects [1,2]. However, although many genes have been effective in treating murine CIA if administrated at a time before disease onset, local intra-articular or periarticular gene transfer has not been highly effective in halting the progression of established disease. IL-4, similar to tumor necrosis factor (TNF)-α and IL-1 inhibitors, has been shown be therapeutic for the treatment of murine CIA when administered intravenously as a recombinant protein, either alone or in combination with IL-10. IL-4 can downregulate the production of proinflammatory and T-helper (Th)1-type cytokines by inducing mRNA degradation and upregulating the expression of inhibitors of proinflammatory cytokines such as IL-1 receptor antagonist (IL-1Ra) [3,4]. IL-4 is able to inhibit IL-2 and IFN-γ production by Th1 cells, resulting in suppression of macrophage activation and the production of the proinflammatory cytokines IL-1, IL-6, IL-8, and TNF-α by monocytes and macrophages [4,5,6,7,8,9].
In order to examine the therapeutic effects of local and systemic IL-4 expression in established CIA, an adenoviral vector carrying the gene for murine IL-4 (Ad-mIL-4) was generated. The ability of Ad-mIL-4 to treat established CIA was evaluated by local periarticular and systemic intravenous injection of Ad-mIL-4 into mice at various times after disease onset.
Materials and methods:
Male DBA/1 lacJ (H-2q) mice, aged 7-8 weeks, were purchased from The Jackson Laboratory (Bar Harbor, ME, USA). The mice were immunized intradermally at the base of tail with 100 μ g bovine type II collagen. On day 21 after priming, mice received a boost injection (intradermally) with 100 μ g type II collagen in incomplete adjuvant. For the synchronous onset of arthritis, 40 μ g lipopolysaccharide (Sigma, St Louis, MO, USA) was injected intraperitoneally on day 28. Ad-mIL-4 was injected periarticularly into the hind ankle joints of mice on day 32 or intravenously by tail vein injection on day 29. Disease severity was monitored every other day using an established macroscopic scoring system ranging from 0 to 4: 0, normal; 1, detectable arthritis with erythma; 2, significant swelling and redness; 3, severe swelling and redness from joint to digit; and 4, maximal swelling with ankylosis. The average of macroscopic score was expressed as a cumulative value for all paws, with a maximum possible score of 16 per mouse. Cytokine production by joint tissue or serum were assessed using enzyme-linked immunosorbent assay (ELISA; R&D Systems, Minneapolis, MN, USA).
To examine the therapeutic effects of IL-4 gene transfer in a murine model of arthritis, 5×108 particles of Ad-mIL-4 and enhanced green fluorescent protein (Ad-eGFP) were administered by periarticular injection into the ankle joints of mice with established disease 4 days after lipopolysaccharide injection. All mice had established disease at time of injection. As shown in Figure 1, the severity of arthritis (Fig. 1a), paw thickness (Fig. 1b), and the number of arthritic paws (Fig. 1c) were all significantly reduced in the Ad-mIL-4 group, compared with the saline- and Ad-eGFP-treated groups. Analysis of the bones in the ankle joints of control arthritic mice showed evidence of erosion with an associated monocytic infiltrate around the joint space compared with the Ad-mIL-4-treated and nonarthritic control joints. In addition, injection of the ankle joints in the hind legs resulted in a therapeutic effect in the front paws. A similar contralateral effect has been observed with adenoviral-mediated delivery of viral (v)-IL-10. Interestingly, a high level of murine IL-10 also was detected from the joint lysates of Ad-mIL-4-treated naïve and arthritic mice, with the production of endogenous IL-10 correlating with the dose of Ad-mIL-4. The administration of recombinant IL-4 protein systemically has been shown to be therapeutic in murine CIA models if given before disease onset. To examine the effect of systemic IL-4 delivered by gene transfer, 1×109 particles of Ad-mIL-4 were injected via the tail vein of collagen-immunized mice the day after lipopolysaccharide injection. Whereas the immunized control mice, injected with Ad-eGFP, showed disease onset on day 3 after lipopolysaccharide injection, Ad-mIL-4-treated mice showed a delay in disease onset and as a reduction in the total number of arthritic paws. Also, systemic injection of Ad-mIL-4 suppressed the severity of arthritis in CIA mice according to arthritis index.
Gene therapy represents a novel approach for delivery of therapeutic agents to joints in order to treat the pathologies associated with RA and osteoarthritis, as well as other disorders of the joints. In the present study we examined the ability of local periarticular and systemic gene transfer of IL-4 to treat established and early-stage murine CIA, respectively. We have demonstrated that both local and systemic administration of Ad-mIL-4 resulted in a reduction in the severity of arthritis, as well as in the number of arthritic paws. In addition, the local gene transfer of IL-4 reduced histologic signs of inflammation and of bone erosion. Interestingly, local delivery of Ad-mIL-4 was able to confer a therapeutic effect to the untreated, front paws through a currently unknown mechanism. In addition, both local and systemic expression of IL-4 resulted in an increase in the level of endogenous IL-10, as well as of IL-1Ra (data not shown). Previous experiments have shown that gene transfer of IL-10 and IL-1 and TNF inhibitors at the time of disease initiation (day 28) is therapeutic. However, delivery of these agents after disease onset appeared to have only limited therapeutic effect. In contrast, the present results demonstrate that IL-4, resulting from local periarticular and systemic injection of Ad-mIL-4, was able partially to reverse progression of established and early-stage disease, respectively. These results, as well as those of others, support the potential application of IL-4 gene therapy for the clinical treatment of RA.
PMCID: PMC17812  PMID: 11056670
adenoviral vectors; collagen-induced arthritis; gene therapy; IL-4; IL-10; rheumatoid arthritis
25.  Lessons learned from gene transfer approaches 
Arthritis Research  1999;1(1):21-24.
Recent technological advances allow the transfer of genes to the synovial lining of joints. As well as opening novel opportunities for therapy, these techniques provide valuable new tools for the study of synovitis and other aspects of the biology of joints in health and disease. This article reviews briefly the results of experiments in which selected genes have been transferred to the knee joints of healthy rabbits and rabbits with antigen-induced arthritis.
PMCID: PMC128865  PMID: 11094409
animal model; cartilage; cytokine; gene therapy; growth factor; rheumatoid arthritis; synovium

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