Autologous Synovial Mesenchymal Stem Cell Transplantation Suppresses Inflammation Caused by Synovial Harvesting and Promotes Healing in a Micro Minipig Repaired Meniscus Model

PURPOSE

Allogeneic synovial mesenchymal stem cells (MSCs) effectively promote meniscus healing in micro minipigs. We investigated the effect of autologous synovial MSC transplantation on meniscus healing in a micro minipig model of meniscus repair showing synovitis after synovial harvesting.

MATERIALS AND METHODS

Synovium was harvested from the left knee of the micro minipigs after arthrotomy and used to prepare synovial MSCs. The left medial meniscus in the avascular region was injured, repaired, and transplanted with synovial MSCs. First, synovitis was compared after 6 weeks in knees with and without synovial harvesting. Second, the repaired meniscus was compared for the autologous MSC group and the control group (in which synovium was harvested but MSCs were not transplanted) 4 weeks after transplantation.

RESULTS

Synovitis was more severe in knees subjected to synovium harvesting than in knees not subjected to harvesting. Menisci treated with autologous MSCs showed no red granulation at the tear of the meniscus, but menisci not treated with MSCS showed red granulation. Macroscopic scores, inflammatory cell infiltration scores, and matrix scores assessed by toluidine blue staining were all significantly better in the autologous MSC group than in the control group without MSCs (n = 6).

CONCLUSION

Autologous synovial MSC transplantation suppressed the inflammation caused by synovial harvesting in micro minipigs and promoted healing of the repaired meniscus.

Ex vivo MRI cell tracking of autologous mesenchymal stromal cells in an ovine osteochondral defect model

BACKGROUND

Osteochondral injuries represent a significant clinical problem requiring novel cell-based therapies to restore function of the damaged joint with the use of mesenchymal stromal cells (MSCs) leading research efforts. Pre-clinical studies are fundamental in translating such therapies; however, technologies to minimally invasively assess in vivo cell fate are currently limited. We investigate the potential of a MRI- (magnetic resonance imaging) and superparamagnetic iron oxide nanoparticle (SPION)-based technique to monitor cellular bio-distribution in an ovine osteochondral model of acute and chronic injuries.

METHODS

MSCs were isolated, expanded and labelled with Nanomag, a 250-nm SPION, and using a novel cell-penetrating technique, glycosaminoglycan-binding enhanced transduction (GET). MRI visibility thresholds, cellular toxicity and differentiation potential post-labelling were assessed in vitro. A single osteochondral defect was created in the medial femoral condyle in the left knee joint of each sheep with the contralateral joint serving as the control. Cells, either GET-Nanomag labelled or unlabelled, were delivered 1 week or 4.5 weeks later. Sheep were sacrificed 7 days post implantation and immediately MR imaged using a 0.2-T MRI scanner and validated on a 3-T MRI scanner prior to histological evaluation.

RESULTS

MRI data demonstrated a significant increase in MRI contrast as a result of GET-Nanomag labelling whilst cell viability, proliferation and differentiation capabilities were not affected. MRI results revealed evidence of implanted cells within the synovial joint of the injured leg of the chronic model only with no signs of cell localisation to the defect site in either model. This was validated histologically determining the location of implanted cells in the synovium. Evidence of engulfment of Nanomag-labelled cells by leukocytes is observed in the injured legs of the chronic model only. Finally, serum c-reactive protein (CRP) levels were measured by ELISA with no obvious increase in CRP levels observed as a result of P21-8R:Nanomag delivery.

CONCLUSION

This study has the potential to be a powerful translational tool with great implications in the clinical translation of stem cell-based therapies. Further, we have demonstrated the ability to obtain information linked to key biological events occurring post implantation, essential in designing therapies and selecting pre-clinical models.

The tenosynovial flap for recalcitrant carpal tunnel syndrome

Operative intervention for recalcitrant carpal tunnel syndrome often utilizes local vascularized tissue to provide coverage of the median nerve in an attempt to limit scarring or adherence of the nerve to its surrounding structures. Although the hypothenar fat pad is the most commonly cited source of vascularized tissue, alternative options do exist. We review the technique of utilizing a pedicled tenosynovial flap as the source of local vascularized tissue for coverage of the median nerve in cases of recalcitrant carpal tunnel syndrome.

Effects of synovial interposition on healing in a canine tendon explant culture model

PURPOSE

To investigate whether synovium interposition between repaired tendon ends can integrate into the tendon repair and improve tendon healing strength in a canine tendon explant culture model.

METHODS

We used 80 flexor digitorum profundus tendons from 10 mixed-breed dogs for this study. The flexor digitorum profundus tendons were assigned to 2 groups: repaired tendons with synovium implanted between the cut tendon ends and repaired tendons without any implantation between the tendon ends. The repaired tendons were cultured for either 2 or 4 weeks and then assessed mechanically for rupture strength and histology.

RESULTS

The strength of the repaired tendons with the synovium interposition was significantly higher (p < .001) than the repaired tendons without interposition at both 2 and 4 weeks. The strength of the repaired tendons at 4 weeks was significantly higher than that at 2 weeks in both groups.

CONCLUSIONS

Interpositional synovial grafts have the potential to accelerate tendon healing when they are implanted at the repair site. The exact mechanism of this effect remains to be elucidated.

Ex vivo serotype-specific transduction of equine joint tissue by self-complementary adeno-associated viral vectors

Cell transplantation for the treatment of joint disease is an important clinical tool. Genetic modification of cells before transplantation has shown enhanced healing. Ex vivo genetic modification of joint tissue cells with various adeno-associated virus (AAV) serotypes has not been investigated. The transduction efficiencies of self-complementary AAV serotypes (1-6 and 8) were determined in joint tissue containing chondrocytes and synoviocytes isolated from equine models. When comparing scAAV serotypes for efficient transduction ex vivo, in chondrocytes versus synoviocytes, serotypes 6 and 2, and serotypes 3 and 2, respectively, appeared superior for gene expression. Unlike adenoviral vectors, no upregulation of inflammatory markers, such as matrix metalloproteinases and aggrecanase, was seen on treatment of joint tissue with AAV vectors ex vivo. Our findings also corroborate that ex vivo transduction of joint tissue can result in high transgene protein levels over time, and transplantation modalities might be feasible using AAV vectors in the treatment of joint-related diseases.

Pedunculated Synovium Grafts in Articular Cartilage Defects in Rabbits

A rabbit model was used to assess the nature of healing tissues in hyaline cartilage defects and to compare the healing in defects treated with pedunculated synovium grafts to those in defects without synovial grafting. Both knees of 28 1-year-old rabbits were operated. A 3 x 2-mm cartilage defect that exposed cancellous bone was created in the non-weight-bearing area of each medial femoral condyle. Each right-knee defect was covered with a pedunculated synovial graft obtained from the same joint, and the left-knee defects were left uncovered as controls. Groups of rabbits were sacrificed at 3, 6, 12, and 24 weeks postsurgery. Sections from each knee were stained with hematoxylin-eosin and safranin O-fast green staining, and were immunohistochemically stained for type II collagen. The healing at each site was histologically scored, and the intensity of staining for type II collagen was graded. At 12 and 24 weeks, statistical comparisons of histological scores revealed significantly more hyaline cartilage tissue in the synovium-grafted defects. At 24 weeks, these same defects showed significantly more type II collagen. Thus, pedunculated synovium transplantation appears to hold promise as a method for repairing hyaline cartilage defects.

Concepts in gene therapy for cartilage repair

Once articular cartilage is injured, it has a very limited capacity for self repair. Although current surgical therapeutic procedures for cartilage repair are clinically useful, they cannot restore a normal articular surface. Current research offers a growing number of bioactive reagents, including proteins and nucleic acids, that may be used to augment various aspects of the repair process. As these agents are difficult to administer effectively, gene-transfer approaches are being developed to provide their sustained synthesis at sites of repair. To augment regeneration of articular cartilage, therapeutic genes can be delivered to the synovium or directly to the cartilage lesion. Gene delivery to the cells of the synovial lining is generally considered more suitable for chondroprotective approaches, based on the expression of anti-inflammatory mediators. Gene transfer targeted at cartilage defects can be achieved by either direct vector administration to cells located at or surrounding the defects, or by transplantation of genetically modified chondrogenic cells into the defect. Several studies have shown that exogenous cDNAs encoding growth factors can be delivered locally to sites of cartilage damage, where they are expressed at therapeutically relevant levels. Furthermore, data is beginning to emerge indicating that efficient delivery and expression of these genes is capable of influencing a repair response toward the synthesis of a more hyaline cartilage repair tissue in vivo. This review presents the current status of gene therapy for cartilage healing and highlights some of the remaining challenges.

[Methanol extract of Celastrus orbiculatu suppresses synovial hyperplasia and cartilage erosion and degradation in rheumatoid arthritis]

OBJECTIVE

To investigate the effects of methanol extract of Celastrus orbiculatu (MECO) on synovial hyperplasia and cartilage erosion and degradation in rheumatoid arthritis (RA), and explore the possible mechanisms to provide clues for new drug development for RA treatment.

METHODS

The articular synovium from patients with RA and normal articular cartilage were co-implanted into the back of severe combined immunodeficient (SCID)mice to establish the chimeric model SCID- HuRAg. Four weeks later, the mice were given MECO intragastrically at 30 mg/day, leflunomide at 500 microg/day or distilled water, respectively, for 4 consecutive weeks. After completion of the treatments, the histological scores of the grafts for synovial hyperplasia, cartilage invasion by synoviocyte and cartilage degradation around the chondrocytes were evaluated, and serum level of tumor necrosis factor-alpha (TNF-alpha) was measured with radioimmunoassay. The expression of TNF-alpha mRNA and the cell apoptosis in the synovium were detected with in situ hybridization (ISH) and TUNEL, respectively, and the results were analyzed with the image analysis system.

RESULTS

The grafts survived in the mice till the end of experiment. MECO and leflunomide, in comparison with distilled water, significantly lowered the scores for synovial hyperlasia (2.00+/-0.76 and 2.25+/-0.89 vs 3.63+/-0.52), cartilage erosion (1.69+/-0.80 and 2.00+/-1.36 vs 3.75+/-0.53), cartilage degradation (1.88+/-0.83 and 2.13+/-0.83 vs 3.63+/-0.74) and serum TNF-alpha level (0.84+/-0.09 and 0.83+/-0.12 vs 0.99+/-0.11 ng/ml). Cell apoptosis of the synovium increased significantly with MECO and leflunomide treatments, but the expression of TNF-alpha mRNA in the synovium decreased significantly in MECO group.

CONCLUSION

MECO can effectively suppress synovial hyperplasia and cartilage erosion and degradation SCID-HuRAg mice by reducing TNF-alpha production in the synovium and promoting synovial apoptosis. MECO can be comparable with leflunomide in their effect, but the former is more effective in suppressing TNF-alpha expression in the synovium.

Elimination of rheumatoid synovium in situ using a Fas ligand 'gene scalpel'

Surgical synovectomy to remove the inflammatory synovium can temporarily ameliorate rheumatoid inflammation and delay the progress of joint destruction. An efficient medically induced programmed cell death (apoptosis) in the rheumatoid synovium might play a role similar to synovectomy but without surgical tissue damage. Gene transfer of Fas ligand (FasL) has increased the frequency of apoptotic cells in mouse and rabbit arthritic synovium. In this study, we investigated whether repeated FasL gene transfer could remove human inflammatory synovial tissue in situ and function as a molecular synovectomy. Briefly, specimens of human synovium from joint replacement surgeries and synovectomies of rheumatoid arthritis (RA) patients were grafted subcutaneously into male C.B-17 severe combined immunodeficiency (SCID) mice. Injections of a recombinant FasL adenovirus (Ad-FasL) into the grafted synovial tissue at the dosage of 10(11) particles per mouse were performed every two weeks. Three days after the fifth virus injection, the mice were euthanized by CO2 inhalation and the human synovial tissues were collected, weighed and further examined. Compared to the control adenovirus-LacZ (Ad-LacZ) and phosphate buffered saline (PBS) injected RA synovium, the Ad-FasL injected RA synovium was dramatically reduced in size and weight (P < 0.005). The number of both synoviocytes & mononuclear cells was significantly reduced. Interestingly, an approximate 15-fold increased frequency of apoptotic cells was observed in RA synovium three days after Ad-FasL injection, compared with control tissues. In summary, our in vivo investigation of gene transfer to human synovium in SCID mice suggests that repeated intra-articular gene transfer of an apoptosis inducer, such as FasL, may function as a 'gene scalpel' for molecular synovectomy to arrest inflammatory synovium at an early stage of RA.

TRAIL-R2 (DR5) mediates apoptosis of synovial fibroblasts in rheumatoid arthritis

TRAIL has been proposed as an anti-inflammatory cytokine in animal models of rheumatoid arthritis (RA). Using two agonistic mAbs specific for TRAIL-R1 (DR4) and TRAIL-R2 (DR5), we examined the expression and function of these death receptors in RA synovial fibroblast cells. The synovial tissues and primary synovial fibroblast cells isolated from patients with RA, but not those isolated from patients with osteoarthritis, selectively expressed high levels of cell surface DR5 and were highly susceptible to anti-DR5 Ab (TRA-8)-mediated apoptosis. In contrast, RA synoviocytes did not show increased expression of TRAIL-R1 (DR4), nor was there any difference in expression of Fas between RA and osteoarthritis synovial cells. In vitro TRA-8 induced apoptosis of RA synovial cells and inhibited production of matrix metalloproteinases induced by pro-inflammatory cytokines. In vivo TRA-8 effectively inhibited hypercellularity of a SV40-transformed RA synovial cell line and completely prevented bone erosion and cartilage destruction induced by these cells. These results indicate that increased DR5 expression and susceptibility to DR5-mediated apoptosis are characteristic of the proliferating synovial cells in RA. As highly proliferative transformed-appearing RA synovial cells play a crucial role in bone erosion and cartilage destruction in RA, the specific targeting of DR5 on RA synovial cells with an agonistic anti-DR5 Ab may be a potential therapy for RA.

Vascularized synovial flap promoting regeneration of the cryopreserved meniscal allograft: experimental study in rabbits

The purpose of this investigation was to evaluate whether a vascularized or free synovial flap or a fibrin clot can promote regeneration of meniscal allograft in the rabbit. Seventy-eight mature New Zealand white rabbits were used. The harvested medial meniscus for the allotransplantation was frozen and stored at -80 degrees C for 2 weeks. After resecting the medial meniscus, an allogenic meniscus was transplanted in the anatomical position (group A). The surface of the graft was covered by a vascularized synovial flap (group B), a free synovial flap (group C), or a fibrin clot (group D). The animals were killed 4, 6, 8, 12, and 16 weeks after transplantation, and the transplants were examined by gross inspection, histology, and microangiography. Connective tissue infiltration into the matrix of the graft was found to begin at 6 weeks (2/5 menisci) and to be complete at 8 weeks (5/5 menisci) in group B, whereas it began at 8 weeks (1/5) in group A. The newly formed repair tissue developed from the synovial tissue and consisted of connective tissue at the beginning and fibrocartilage later. The fibrocartilage had appeared at 8 weeks (3/5) in group B but not yet in group A (0/5). A free flap or fibrin clot coverage resulted in delayed revascularization compared to a vascularized synovial flap, but both tended to achieve faster revascularization than the controls. We concluded that regeneration of allografted meniscus with a vascularized synovial flap occurs earlier than under other conditions. Thus, allografts with synovial implantation may be considered for management of the meniscectomized knee.

Increased expression of alpha(1,3)-fucosyltransferase-VII and P-selectin binding of synovial fluid T cells in juvenile idiopathic arthritis

OBJECTIVE

The mechanisms controlling the recruitment of T helper type 1 (Th1) cells to the inflamed synovium are not fully understood. Here, we focus on alpha(1,3)-fucosyltransferase-VII (FucT-VII), an enzyme responsible for the generation of functional P- and E-selectin ligands that is upregulated in Th1 cells.

METHODS

Expression of transcripts encoding FucT-VII, interferon-gamma (IFN-gamma), and interleukin 12Rbeta2 (IL-12Rbeta2) were analyzed in T cells purified from synovial fluid (SF) and from peripheral blood (PB) of children with juvenile idiopathic arthritis (JIA) using kinetic reverse transcriptase polymerase chain reaction analysis. Binding of SF and PB T cells to P-selectin was determined by flow cytometry using a soluble P-selectin/IgG1 fusion molecule. Recruitment of T cells to synovial tissue in vivo was studied by analyzing the migration of FucT-VII transfected Jurkat T cells into human rheumatoid synovial tissue grafted into SCID mice.

RESULTS

In patients with JIA, the mRNA levels of FucT-VII, as well as of IFN-gamma and IL-12Rbeta2, were up-regulated in SF T cells compared to paired PB T cells. A higher expression of FucT-VII mRNA in SF T cells was associated with increased binding of T cells to P-selectin. Moreover, FucT-VII expression and increased P-selectin binding capacity of T cells were associated with a polyarticular course of oligoarticular JIA. Expression of FucT-VII in Jurkat T cells resulted in an increased accumulation of these cells in human rheumatoid synovial tissue grafted into SCID mice.

CONCLUSION

Our data indicate an important role of FucT-VII in the enhanced homing of T cells to the inflamed synovium.

Albumin-based drug delivery as novel therapeutic approach for rheumatoid arthritis

We reported recently that albumin is a suitable drug carrier for targeted delivery of methotrexate (MTX) to tumors. Due to pathophysiological conditions in neoplastic tissue, high amounts of albumin accumulate in tumors and are metabolized by malignant cells. MTX, covalently coupled to human serum albumin (MTX-HSA) for cancer treatment, is currently being evaluated in phase II clinical trials. Because synovium of patients with rheumatoid arthritis (RA) shares various features observed also in tumors, albumin-based drug targeting of inflamed joints might be an attractive therapeutic approach. Therefore, the pharmacokinetics of albumin and MTX in a mouse model of arthritis was examined. Additionally, uptake of albumin by synovial fibroblasts of RA patients and the efficacy of MTX and MTX-HSA in arthritic mice were studied. The results show that when compared with MTX, significantly higher amounts of albumin accumulate in inflamed paws, and significantly lower amounts of albumin are found in the liver and the kidneys. The protein is metabolized by human synovial fibroblasts in vitro and in vivo. MTX-HSA was significantly more effective in suppression of the onset of arthritis in mice than was MTX. In conclusion, albumin appears to be a suitable drug carrier in RA, most likely due to effects on synovial fibroblasts, which might increase therapeutic efficacy and reduce side effects of MTX.

Amelioration of antigen-induced arthritis in rats by transfer of extracellular superoxide dismutase and catalase genes

Reactive oxygen species (ROS) have been implicated in the pathogenesis of rheumatoid arthritis (RA), while antioxidant enzymes, such as extracellular superoxide dismutase (EC-SOD) and catalase, block radical-induced events. The present study tested if the ex vivo transfer of EC-SOD and catalase genes alone or in combination in the knee joint of rats with monoarticular antigen-induced arthritis (AIA) was anti-inflammatory, and examined the potential mechanisms involved. Synoviocytes isolated from female Wistar rats were immortalized with a retroviral vector SUV19.5. These cells were permanently transfected with an EC-SOD expression plasmid (pEC-SODZeo) or a catalase expression plasmid (pCatalaseZeo) to create cells overexpressing EC-SOD or catalase, as measured by RT-PCR and Western blots. The cells were engrafted in knee joints of animals at the time of the induction of AIA. Three gene transfer groups, an EC-SOD group, a catalase group and a combined therapy group (EC-SOD and catalase) were included in these experiments. Animals in the control group were engrafted with synoviocytes transfected with the plasmid pZeoSV2 without an insert. Clinical and histological assessments were performed, as well as tissue measurements of SOD, catalase and gelatinase activities. Ex vivo gene transfer of EC-SOD and catalase into rat knee joints produced about a six- to seven-fold increase in EC-SOD activity and a two- to three-fold increase in catalase activity compared with the control animals. Rats treated with cells overexpressing EC-SOD, catalase or a combination of EC-SOD and catalase showed significant suppression of knee joint swelling, decreased infiltration of inflammatory cells within the synovial membrane and reduced gelatinase activity in knee joints, compared with animals receiving cells transfected with the plasmid alone. No statistically significant difference was found between the groups treated with cells overexpressing EC-SOD, catalase or a combination of both. Gene therapy involving the local intra-articular overexpression of two antioxidant enzymes, EC-SOD and catalase, was anti-inflammatory in AIA. One mechanism appears to be the suppression of gelatinase activities by both EC-SOD and catalase.

Skeletal muscle repair by adult human mesenchymal stem cells from synovial membrane

We have demonstrated previously that adult human synovial membrane-derived mesenchymal stem cells (hSM-MSCs) have myogenic potential in vitro (De Bari, C., F. Dell'Accio, P. Tylzanowski, and F.P. Luyten. 2001. Arthritis Rheum. 44:1928-1942). In the present study, we have characterized their myogenic differentiation in a nude mouse model of skeletal muscle regeneration and provide proof of principle of their potential use for muscle repair in the mdx mouse model of Duchenne muscular dystrophy. When implanted into regenerating nude mouse muscle, hSM-MSCs contributed to myofibers and to long term persisting functional satellite cells. No nuclear fusion hybrids were observed between donor human cells and host mouse muscle cells. Myogenic differentiation proceeded through a molecular cascade resembling embryonic muscle development. Differentiation was sensitive to environmental cues, since hSM-MSCs injected into the bloodstream engrafted in several tissues, but acquired the muscle phenotype only within skeletal muscle. When administered into dystrophic muscles of immunosuppressed mdx mice, hSM-MSCs restored sarcolemmal expression of dystrophin, reduced central nucleation, and rescued the expression of mouse mechano growth factor.

Inhibition of cartilage destruction by double gene transfer of IL-1Ra and IL-10 involves the activin pathway

The objective of the study was to determine the effects and the molecular background of interleukin-1 receptor antagonist (IL-1Ra) and vIL-10 double gene transfer into human synovial fibroblasts from patients with rheumatoid arthritis (RA) using the SCID mouse model for cartilage erosion in RA. RA synovial fibroblasts were transduced with retro- or adenoviruses encoding IL-1Ra and/or viral IL-10 (vIL-10). SCID mice were engrafted subcutaneously with IL-1Ra and vIL-10 transduced human rheumatoid synovial fibroblasts and normal cartilage. In parallel, gene expression analysis before and after gene transfer using RNA arbitrarily primed PCR in combination with cDNA array was performed. vIL-10 and IL-1Ra double gene transfer resulted in inhibition of cartilage invasion and degradation by RA synovial fibroblasts when compared with control transduced and non-transduced implants. Expression of key genes that were altered after double gene transfer were related to the activin pathway. The results demonstrate not only that virus-based gene transfer using a combination of two joint-protective genes is a feasible approach to inhibit cartilage degradation by activated RA synovial fibroblasts, but also that the underlying molecular effects include modulation of the activin pathway.

Annexin 1 modulates monocyte-endothelial cell interaction in vitro and cell migration in vivo in the human SCID mouse transplantation model

The effect of the glucocorticoid inducible protein annexin 1 (ANXA1) on the process of monocytic cell migration was studied using transfected U937 cells expressing variable protein levels. An antisense (AS) (36.4AS; approximately 50% less ANXA1) and a sense (S) clone (15S; overexpressing the bioactive 24-kDa fragment) together with the empty plasmid CMV clone were obtained and compared with wild-type U937 cells in various models of cell migration in vitro and in vivo. 15S-transfected U937 cells displayed a reduced (50%) degree of trans-endothelial migration in response to stromal cell-derived factor-1alpha (CXC chemokine ligand 12 (CXCL12)). In addition, the inhibitory role of endogenous ANXA1 on U937 cell migration in vitro was confirmed by the potentiating effect of a neutralizing anti-ANXA1 serum. Importantly, overexpression of ANXA1 in clone 15S inhibited the extent of cell migration into rheumatoid synovial grafts transplanted into SCID mice. ANXA1 inhibitory effects were not due to modifications in adhesion molecule or CXCL12 receptor (CXCR4) expression as shown by the similar amounts of surface molecules found in transfected and wild-type U937 cells. Likewise, an equal chemotactic response to CXCL12 in vitro excluded an intrinsic defect in cell motility in clones 15S and 36.4AS. These data strongly support the notion that ANXA1 critically interferes with a leukocyte endothelial step essential for U937 cell, and possibly monocyte, transmigration both in vitro and in vivo.

Antirheumatic effects of humanized anti-Fas monoclonal antibody in human rheumatoid arthritis/SCID mouse chimera

OBJECTIVE

Anti-Fas monoclonal antibodies (Mab) are considered to be a potential therapeutic agent for rheumatoid arthritis (RA). However, Fas mediated liver and chondrocyte damage is a serious problem in its clinical application. m-HFE7A, a novel anti-Fas Mab, selectively induces apoptosis in inflammatory cells. We succeeded in humanizing m-HFE7A to obtain h-HFE7A. We investigated the therapeutic effects of h-HFE7A Mab in RA.

METHODS

We investigated the apoptosis-inducing activities of h-HFE7A on human Fas ligand transfected cells and cultured human activated lymphocytes (human peripheral blood mononuclear cells and isolated human RA synovial lymphocytes), synoviocytes, and chondrocytes. We then examined the effects of h-HFE7A Mab in vivo using SCID-HuRAg mice implanted with human RA tissue.

RESULTS

Administration of h-HFE7A Mab alone did not induce apoptosis in cultured human Fas ligand transfected cells and activated lymphocytes. However, apoptosis-inducing activities were noted by this Mab crosslinking with a secondary antibody or Fcgamma receptor positive cells. In contrast, no apoptosis induction by h-HFE7A was observed on cultured synoviocytes and chondrocytes with or without crosslinking. Thus the crosslinking with Fcgamma receptor positive cells is essential for the efficacy of this Mab in vivo. In the implanted tissue of the SCID-HuRAg mice, the number of inflammatory cells was significantly decreased in the h-HFE7A Mab treated group compared to the IgG treated control group. Moreover, there were only negligible effects in synoviocytes and chondrocytes with the h-HFE7A Mab.

CONCLUSION

Administration of this novel humanized anti-Fas Mab may provide a new treatment for RA by inducing Fas mediated apoptosis in inflammatory cells.

Identification of synovium-specific homing peptides by in vivo phage display selection

OBJECTIVE

To identify homing peptides specific for human synovium that could be used as targeting devices for delivering therapeutic/diagnostic agents to human joints.

METHODS

Human synovium and skin were transplanted into SCID mice. A disulfide-constrained 7-amino acid peptide phage display library was injected intravenously into the animals and synovial homing phage recovered from synovial grafts. Following 3-4 cycles of enrichment, DNA sequencing of homing phage clones allowed the identification of specific peptides that were synthesized by a-fluorenylmethyloxycarbonyl chemistry and used in competitive in vivo assays and immunohistochemistry analyses.

RESULTS

We isolated synovial homing phages displaying specific peptides that distinctively bound to synovial but not skin or mouse microvascular endothelium (MVE). They retained their tissue homing specificity in vivo, independently from the phage component, the original pathology of the transplanted tissue, and the degree of human/murine graft vascularization. One such peptide (CKSTHDRLC) maintained synovial homing specificity both when presented by the phage and as a free synthetic peptide. The synthetic peptide also competed with and inhibited in vivo the binding of the parent phage to the cognate synovial MVE ligand.

CONCLUSION

This is the first report describing peptides with homing properties specific for human synovial MVE. This was demonstrated using a novel approach targeting human tissues, transplanted into SCID mice, directly by in vivo phage display selection. The identification of such peptides opens the possibility of using these sequences to construct joint-specific drug delivery systems that may have considerable impact in the treatment of arthritic conditions.

Study of the mechanism involved in angiogenesis and synovial cell proliferation in human synovial tissues of patients with rheumatoid arthritis using SCID mice

To examine whether synovial cell proliferation is due to angiogenesis, we studied the relationship between the inhibition of synovial cell proliferation and an angiogenesis inhibitor, TNP-470, in human synovial tissues. Human synovial tissues were implanted into the back of SCID mice (SCID-HuAg mice). Sixteen mice were divided into two groups of eight mice each: the untreated group (vehicle group) and the TNP-470-treated group that received a dose of 10 mg/kg body weight by subcutaneous injection. The number of blood vessels and synovial lining cells clearly increased in the vehicle group, but the number of synovial lining cells clearly decreased and the blood vessels were hardly detected in the TNP-470 group. Immunohistochemically, cells that stained positively for the anti-proliferating cell nuclear antigen (PCNA) mAb were abundant in synovial lining cells and endothelial cells in synovial tissues. Cells that stained positively for the anti-CD34 polyclonal antibody were abundant in the endothelial cells in the vehicle group, but these positively stained cells were hardly detected in the TNP-470 group. The PCNA positivity ratio in the vehicle group was 0.64 +/- 0.019, whereas that in the TNP-470 group was 0.199 +/- 0.007. The numbers of cells that stained positively for anti-CD34 polyclonal antibody were 242 +/- 13.4 in the vehicle group and 153 +/- 6.73 in the TNP-470 group per 10 microscopic fields. Cells that stained positively for anti-mouse CD31 mAb were mainly localized in the synovial lining, but invaded the subsynovial lining layer in human synovial tissues. On the other hand, cells that stained positively for anti-human CD31 mAb were mainly localized in the subsynovial lining layer. We found that endothelial cell proliferation is dependent on angiogenesis based on the result that angiogenesis and synovial cell proliferation were inhibited by treatment with TNP-470.

Treatment with the angiogenesis inhibitor endostatin: a novel therapy in rheumatoid arthritis

OBJECTIVE

An endostatin that inhibits angiogenesis dependent tumor growth is being tested as an antitumor agent. The neoangiogenesis condition of cancer is essentially identical to that of rheumatoid arthritis (RA). Thus antiangiogenic treatment has potential for treatment of RA. We investigated the effects of human recombinant endostatin on human RA synovial tissue by use of a novel model of RA, in which human RA tissue is grafted into SCID mice (SCID-HuRAg).

METHODS

Ten or 50 mg/kg of human recombinant endostatin was administered by percutaneous direct intrasynovial injection in each of 7 SCID-HuRAg mice. We examined the volume of the grafted tissue mass and the histological changes 7 days after endostatin administration. Six control mice received phosphate buffered saline in the same manner.

RESULTS

The grafted synovial volume of SCID-HuRAg mice was significantly decreased by endostatin administration. The number of inflammatory cells (macrophages and lymphocytes) was also significantly reduced in a dose dependent manner. The number of vessels that were counted by von Willebrand factor VIII and type IV collagen positive cells was decreased, although apoptotic cells were increased in RA synovia.

CONCLUSION

The results suggest that antiangiogenesis treatment using endostatin represents a potential new therapeutic strategy for RA.

[Role of cell migration in the pathogenesis of rheumatoid arthritis: in vivo studies in SCID mice transplanted with human synovial membrane]

OBJECTIVE

Adhesion mechanisms play a central role in the recruitment of leukocytes which characteristically infiltrate rheumatoid synovium. Therefore, we adapted an animal model, in which human rheumatoid synovium was transplanted into severe combined immunodeficient (SCID) mice, to study the effects of Tumor Necrosis Factor-alpha (TNF-alpha) in modulatine leukocyte migration and to investigate the chemotactic potential of Stromal Derived Factor-1 alpha (SDF-1 alpha).

MATERIALS AND METHODS

Human synovium samples, obtained from patients undergoing joint replacement, were divided into two parts. One was analysed by immunohistology and the other was implanted subcutaneously into SCID mice under general anaesthesia. Four weeks post-transplantation, grafts were injected with optimal dose of SDF-1, TNF-alpha or saline (negative control). At the same time, animals were injected iv with fluorescently labelled cells. 48 hours later mice were sacrificed and grafts removed for cryo-hystology. The number of cells migrating to the grafts was determined by UV-microscopy and the results expressed as cells per high power field.

RESULTS AND CONCLUSIONS

In these studies we provide the evidence that: 1) the animal model, in which human tissues are grafted into SCID mice, can be used to study cell migration under controlled experimental conditions; 2) direct intragraft injection of TNF-alpha increases lymphocytes migration and up-regulates the expression of human adhesion molecules (CAMs) and 3) SDF-1 alphainjected intragraft increases the migration of the pro-myelo-monocytic U937 cells to synovial transplants, even more efficiently than TNF-alpha, but without modifications of CAMs' expression.

Stromal cell-derived factor 1 (CXCL12) induces monocyte migration into human synovium transplanted onto SCID Mice

OBJECTIVE

The mechanisms by which monocyte/macrophage cells migrate to the joint involve a series of integrated adhesion and signaling events in which chemokines and their receptors are strongly implicated. This study was undertaken to investigate the hypothesis that stromal cell-derived factor 1 (SDF-1), a CXC chemokine (CXCL12), plays a critical role in monocyte/macrophage localization to synovium.

METHODS

SDF-1 and CXC receptor 4 (CXCR4) expression in rheumatoid arthritis (RA) and osteoarthritis synovium and graft SDF-1, tumor necrosis factor alpha (TNF alpha), and human and murine vascular markers were examined by immunohistochemistry and double-immunofluorescence. The functional capacity of SDF-1 to modulate monocyte migration into joints was investigated by examining the localization of pro-myelomonocytic U937 cells into synovial tissue transplanted into SCID mice. SDF-1, TNF alpha, or saline was injected into graft sites and response determined by the number of fluorescently labeled U937 cells (injected intravenously) detected in grafts by ultraviolet microscopy.

RESULTS

SDF-1 and CXCR4 were highly expressed in CD68+ cells in the RA synovium. SDF-1 induced U937 cell migration in vitro and in vivo in a dose-dependent manner and, in vivo, SDF-1 was more effective than TNF alpha. In contrast to TNF alpha, SDF-1 did not induce intracellular adhesion molecule 1 in transplant microvasculature. Furthermore, intragraft injection of SDF-1 did not up-regulate TNF alpha, or vice versa.

CONCLUSION

This study demonstrates, for the first time, that SDF-1 is functional in vivo when injected into synovial grafts. In addition, SDF-1 is more potent than TNF alpha, and its mechanisms of action appear to be autonomous. Therefore, SDF-1 may be an important TNF-independent molecule involved in the migration to and retention of inflammatory effector cells in the joint.

The role of TNF-alpha in the pathogenesis of inflammation and joint destruction in rheumatoid arthritis (RA): a study using a human RA/SCID mouse chimera

OBJECTIVE

In order to elucidate which cytokine preferentially stimulates the synovium in patients with rheumatoid arthritis (RA), we investigated the roles of tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) using SCID mice engrafted with human RA tissue (SCID-HuRAg).

METHODS

The SCID-HuRAg mice were prepared according to our previously described method. First, SCID-HuRAg mice were treated with chimeric anti-TNF-alpha monoclonal antibody (mAb, 100 microg/mouse) and histological changes were examined 4 weeks after the initial treatment. Secondly, a total of 100 microg of recombinant TNF-alpha or IL-6 (0.6 microg/h) was administered daily to mice using an osmium pump. The histological changes and serum cytokine levels were examined 4 weeks after the initial administration. Human immunoglobulin G (IgG) was administered to mice as a control.

RESULTS

Synovial inflammatory cells were significantly decreased after the anti-TNF-alpha mAb treatment; conversely, the degree of synovial inflammation was significantly exacerbated by TNF-alpha administration. The levels of both IL-6 and TNF-alpha in sera were significantly increased by recombinant TNF-alpha administration, while TNF-alpha levels were unchanged by IL-6 administration. This suggests that TNF-alpha controls IL-6 production. Despite the profound changes in inflammation, we found no effects on bone and no articular cartilage damage was produced by TNF-alpha.

CONCLUSION

This study provides strong evidence that TNF-alpha is a key molecule in the control of the inflammatory changes that occur in the RA synovium. In addition, TNF-alpha regulates IL-6 production. However, other inflammatory pathways independent of TNF-alpha may contribute to the bone and cartilage damage seen in RA.

Stimulation of collagenase 3 expression in synovial fibroblasts of patients with rheumatoid arthritis by contact with a three-dimensional collagen matrix or with normal cartilage when coimplanted in NOD/SCID mice

OBJECTIVE

To study the expression of collagenase 3 (matrix metalloproteinase 13 [MMP-13]) and collagenase 1 (MMP-1) in synovial fibroblasts from patients with rheumatoid arthritis (RA) when cultured within 3-dimensional collagen gels or coimplanted with normal cartilage in immunodeficient NOD/SCID mice.

METHODS

Messenger RNA (mRNA) and protein expression of collagenase 3 and collagenase 1 were characterized in synovial and skin fibroblasts by Northern blot and Western blot analysis. The mRNA expression of both collagenases in cell-cartilage implants in NOD/SCID mice was investigated by in situ hybridization in combination with immunohistochemistry of human fibroblasts.

RESULTS

Synovial fibroblasts coimplanted with normal cartilage in NOD/SCID mice deeply invaded adjacent cartilage tissue. In this in vivo system of cartilage destruction, collagenase 3 mRNA was induced in synovial fibroblasts at sites of cartilage erosion, while the expression of collagenase 1 mRNA could not be detected. Culture of synovial fibroblasts within 3-dimensional collagen gels was associated with a marked increase in collagenase 3 mRNA expression and proenzyme production. This stimulatory effect was 1 order of magnitude higher in comparison with a 2-4-fold increase upon treatment with interleukin-1beta or tumor necrosis factor a. In contrast, mRNA expression and proenzyme production of collagenase 1 were increased strongly, and to a similar extent, either by contact with 3-dimensional collagen or by proinflammatory cytokines.

CONCLUSION

The expression of collagenase 3, in contrast to that of collagenase 1, is preferentially stimulated in synovial fibroblasts by 3-dimensional collagen rather than by proinflammatory cytokines. The induction of collagenase 3 by cell-matrix interactions represents a potential mechanism contributing to the invasive phenotype of synovial fibroblasts at sites of synovial invasion into cartilage in RA.

Inflammation, immune reactivity, and angiogenesis in a severe combined immunodeficiency model of rheumatoid arthritis

Severe combined immunodeficiency (SCID) mice were engrafted with rheumatoid arthritis (RA) synovium and evaluated to determine whether RA synovial morphology and function were maintained in the RA-SCID grafts. The four major components of RA synovitis, inflammation, immune reactivity, angiogenesis, and synovial hyperplasia persisted in RA-SCID grafts for 12 weeks. Retention of chronic inflammatory infiltrates was demonstrated by histological evaluation and by immunohistology for CD3, CD20, and CD68. Staining for CD68 also revealed that the grafts had undergone reorganization of the tissue, possibly as a result of fibroblast hyperplasia. Immune and inflammatory components were confirmed by the detection of human immunoglobulins and human interleukin-6 in serum samples obtained from grafted animals. Human blood vessels were detected by dense expression of CD31. Small vessels persistently expressed the vitronectin receptor, alpha v beta 3, a marker of angiogenesis. All vessels expressed VAP-1, a marker of activated endothelial cells. Finally, the grafts retained the ability to support immigration by human leukocytes, as demonstrated by the functional capacity to recruit adoptively transferred 5- (and -6)-carboxyfluorescein diacetate succinimidyl ester-labeled T cells. T cells entering the RA-SCID grafts became activated and produced interferon-gamma, as detected by reverse transcriptase-polymerase chain reaction analysis. These studies demonstrate that the RA-SCID model maintains many of the phenotypic and functional features of the inflamed RA synovium.

Recruitment of mononuclear leucocytes to osteoarthritic human synovial xenografts in the ears of SCID mice

A system has been established to assess the recruitment of 99mTc-hexamethylpropylene amine oxamine (99mTc-HMPAO)-labelled PBMC and [125I]iododeoxyuridine-labelled Con A stimulated lymphoblasts to allogeneic human synovial xenografts in the ears of SCID mice. Successful engraftment of osteoarthritic synovium was achieved in approximately 90% of cases and a connection between the human microvasculature of the xenograft and the circulation of the mouse was shown. Cells were delivered to the xenograft by a system of regional vascular perfusion, thus avoiding the major murine vascular beds. The accumulation of 99mTc-HMPAO-labelled PBMC in mouse ears was monitored in real time. Direct injection of xenograft-bearing ears with recombinant human TNF-alpha, 7 h prior to perfusion, increased the accumulation of both PBMC and lymphoblasts in cytokine-injected ears compared to contralateral control-injected ears. Autoradiography revealed the presence of [125I]iododeoxyuridine-labelled lymphoblasts associated with human microvasculature within the xenograft. However, the increased accumulation of lymphoblasts in cytokine-injected ears occurred in the tissues surrounding the xenograft, where lymphoblasts were associated more often with murine than human vessels. Although the system described offers advantages over similar models, the propensity for mouse endothelium to interact with human leucocytes is likely to be a generic disadvantage for models of human leucocyte recruitment to xenografts in immunodeficient mice.

Methotrexate inhibits rheumatoid synovitis by inducing apoptosis

OBJECTIVE

To clarify the pharmacological action of methotrexate (MTX) on the synovium of patients with rheumatoid arthritis (RA) using severe combined immunodeficient (SCID) mice in which human RA synovial tissue had been grafted (SCID-HuRAg).

METHODS

One month after engraftment of human RA tissue into SCID mice, MTX (0.3 mg/kg) was administered orally, then the appearance of apoptosis in the grafted tissue was examined by TdT mediated dUTP nick end labeling (TUNEL) staining and electron microscopy at various time points after MTX administration. In cultured synovial cells, synovial apoptotic changes after MTX treatment were studied by agarose gel electrophoresis and flow cytometric analysis. To compare the histological changes induced by MTX with those induced by other disease modifying antirheumatic drugs (DMARD) and a nonsteroidal antiinflammatory drug, histological examination of the grafted synovial tissues from SCID-HuRAg mice was conducted after 4 weeks of oral administration of MTX (0.3 mg/kg/week), salazosulfapyridine (30 mg/kg/day), auranofin (0.2 mg/kg/day), bucillamine (10 mg/kg/day), or indomethacin (2 mg/kg/day).

RESULTS

A significant decrease in the number of inflammatory cells was observed in the grafted synovial tissue of MTX treated SCID-HuRAg. A similar antiinflammatory effect was not observed with the other DMARD. Induction of apoptosis was noted with MTX treatment but not with the others. The pro-apoptotic effect of MTX was also observed in synovial cell cultures.

CONCLUSION

MTX induces apoptosis in RA synovium that, in turn, may contribute to its antiinflammatory effect on RA synovitis.

Expression of angiogenic factors in juvenile rheumatoid arthritis: correlation with revascularization of human synovium engrafted into SCID mice

OBJECTIVE

Although increased vascularity was noted in early histopathologic studies of juvenile rheumatoid arthritis (JRA) synovium, the available data on angiogenesis in JRA are very limited. The main purposes of this study were to assess expression of the key angiogenic factors in JRA synovium, and to evaluate a SCID mouse model of JRA as an approach to study in vivo regulation of the expression of these factors in JRA.

METHODS

RNase protection assay was used to assess the expression of the key angiogenic factors in fresh JRA synovium and in JRA synovial tissue fragments that had been minced and then implanted into SCID mice. Vascularity of the samples was assessed by immunohistochemical staining for von Willebrand factor. Synovial specimens obtained from patients with osteoarthritis (OA) or other noninflammatory arthropathies were used as controls.

RESULTS

Detectable levels of messenger RNA for vascular endothelial growth factor and angiopoietin 1 and their respective receptors, as well as endoglin and thrombin receptors, were present in all JRA tissue specimens studied. The levels of expression of these factors in JRA tissues were significantly higher than those in tissues obtained from patients with OA or other noninflammatory arthropathies. Furthermore, increased expression of the key angiogenic factors in the fresh JRA tissues correlated with the exuberant revascularization of JRA minced tissue fragments implanted into SCID mice. This was in sharp contrast to the poor revascularization of implanted OA tissues.

CONCLUSION

JRA synovium is characterized by high angiogenic activity. SCID mouse-human JRA synovium chimeras may provide a good approach to study the in vivo regulation of angiogenesis in JRA.

Tumour necrosis factor-alpha (TNF-alpha) enhances lymphocyte migration into rheumatoid synovial tissue transplanted into severe combined immunodeficient (SCID) mice

Adhesion mechanisms play a major role in the recruitment of peripheral blood lymphocytes (PBL) which characteristically infiltrate rheumatoid arthritis (RA) synovium and other chronically inflamed tissues. Through a sequential series of complex integrated adhesion and signalling events, 'multistep model of migration', specific subsets of PBL are recruited into inflamed tissues. In this process both leucocyte receptors and microvascular endothelial (MVE) counter-receptors play a critical role. The MVE in particular, during an inflammatory state, is the target of various inflammatory mediators that cause the up-regulation of several cell adhesion molecules (CAM). One of the most important factors known to be a powerful inducer of MVE CAM is TNF-alpha. Conversely, blocking TNF-alpha causes a down-modulation of CAM expression. To test directly the capacity of TNF-alpha to induce cell migration into RA synovium we adapted a model in which synovial grafts were implanted into SCID mice subcutaneously. Using this model we demonstrate that: (i) transplants remain viable and become vascularized and fed by mouse subdermal vessels; (ii) the mouse vasculature connects to the transplant vasculature which maintains the ability to express human CAM; (iii) intragraft injections of TNF-alpha up-regulate the expression of human CAM, following the down-regulation which occurred 4 weeks post-transplantation; and (iv) the up-regulation of graft CAM is associated with increased human PBL migration into the transplants. This study provides direct evidence in vivo of the capacity of TNF-alpha to induce cell migration. In addition, it provides the experimental background for the optimal use of this model.

An experimental study in the chick embryo chorioallantoic membrane of the anti-angiogenic activity of cyclosporine in rheumatoid arthritis versus osteoarthritis

OBJECTIVE AND DESIGN

Angiogenesis plays an important role in the pathogenesis of rheumatoid arthritis (RA) and correlates with clinical score, synovial hyperplasia and infiltration of inflammatory cells. Many of the available treatments for RA have been shown to possess some degree of anti-angiogenic activity. Here, we studied the effect of cyclosporine, which exerts anti-angiogenic activity in vitro and in vivo [1] on angiogenesis induced in vivo in the chick embryo chorioallantoic membrane (CAM) by synovial RA and osteoarthritis (OA) tissues.

MATERIAL AND METHODS

Wet synovial biopsies from 10 RA and 6 OA patients were treated with vehicle alone or with cyclosporine and implanted on the CAM at day 8 of incubation. On day 12, CAM tissues were assessed for the extent of angiogenesis and mononuclear cell infiltration.

RESULTS

Cyclosporine inhibited angiogenesis and reduced the number of mononuclear cells in the CAM extracellular matrix only in RA implants.

CONCLUSIONS

These data provide further evidence for a central role of new-formed blood vessels in RA. Moreover, cyclosporine on account of both its immunosuppressive and its anti-angiogenic activity can be proposed for the treatment of RA.

Novel gene therapy for rheumatoid arthritis by FADD gene transfer: induction of apoptosis of rheumatoid synoviocytes but not chondrocytes

Synovial cells in the rheumatoid synovium show abnormal proliferation, leading to joint destruction. Rheumatoid synovial cells express functional Fas antigen and are susceptible to Fas-mediated apoptosis. We have proposed the induction of apoptosis by Fas/Fas ligand system of proliferative rheumatoid synovium as a novel therapy for rheumatoid arthritis (RA). We have recently reported that Fas-associated death domain protein (FADD) plays a key role in Fas-mediated apoptosis of synovial cells in patients with RA. In this study, we determined whether FADD gene transfer could induce apoptosis of RA synoviocytes in vitro and in vivo. Transfection of FADD gene by adenoviral vector into cultured RA synoviocytes induced up-regulation of FADD expression and apoptosis. In addition, local injection of FADD adenovirus (Ad-FADD) eliminated synoviocytes in vivo by induction of apoptosis of proliferating human rheumatoid synovium engrafted in severe combined immunodeficiency mouse, which is the most suitable animal model of RA for the evaluation of treatment strategy in vivo. In addition, Ad-FADD-induced apoptosis was limited to cells of the synovium tissue and did not affect chondrocytes. Our results strongly suggest that FADD gene transfer can induce apoptosis of RA synoviocytes both in vitro and in vivo, suggesting that FADD gene transfer might be effective in the treatment of RA.

A method of tracking donor cells after simulated autologous transplantation: a study using synovial cells of transgenic rats

A transgenic rat was used as a transplantation donor to simulate autologous transplantation. The sex-matched transplantation between a female transgenic and a wild-type rat can theoretically be regarded as an autologous transplantation due to the genetic agreement of these rats except for the non-protein-producing transgenes. Transgene-containing synovial cells were tracked in the joint using this autologous transplantation model. The transgenes in the donor synovial cells were detected using in situ hybridization (ISH), while mitotic activities were simultaneously examined by immunodetection of 5-bromo-2'-deoxyuridine (BrdU). A defect was generated in the knee joint capsule of a Fischer 344 (wild-type) rat. The synovium of a transgenic rat was sutured to the defect of the wild-type rat in group 1 and was allowed to free float in the joint in group 2. A large number of BrdU-labeled, transgene-containing synovial cells were detected in both groups at 3 days. The number of these cells then decreased, but they could still be identified even at 4 weeks after autologous transplantation. These results indicated that transplanted synovial cells were viable in the joint for at least 4 weeks. Furthermore, the transgenic rat was shown to be an effective animal model for distinguishing the extrinsic from the intrinsic cells in the cellular intermixed tissues in vivo. The combined method of ISH for detecting transgene-containing cells and the immunohistochemistry of BrdU for detecting proliferating cells was also shown to be effective for tracking the viability of extrinsic cells after autologous transplantation.

Systemic characteristics of chronic arthritis induced by transfer of human rheumatoid synovial membrane into SCID mice (human/murine SCID arthritis)

Erosive human/murine (hu/mu) SCID arthritis, caused by unilateral engrafting of human rheumatoid arthritis synovial membrane (RA-SM) in the knee joints of SCID mice, was monitored for up to 18 weeks by scintigraphic, radiological, morphological and immunohistochemical analyses.(99m)Tc-DPD scintigraphy and histology revealed secondary, oligoarticular spreading of arthritis to contralateral knees and hips, but not to forelimb joints. Also, there were no extraarticular manifestations. At 18 weeks, surviving human cells were found within the pannus, but not directly at the cartilage erosion front, where fibroblast-like cells and macrophages of murine origin predominated. The latter cells also predominated in secondarily affected joints, where no human cells were detectable. Preventive depletion of murine NK-cells by anti-asialo-GMI antibodies, to check the influence of NK cells independently of strain and MHC system, combined with application of autologous human PBMN cells, had virtually no effects on the disease process. The completeness of the SCID defect was not critical, i.e. T cells were completely absent in the organs examined, and the presence of a few B cells in the spleen did not correspond to particular disease features. The SCID defect itself had a clear impact, since, in the chronic phase, SCID.bg and RAG-2(-/-)knockout mice developed less consistent pathological/scintigraphic signs of disease than SCID mice. Thus, unilaterally-induced hu/mu SCID arthritis is an oligoarticular disorder of the hindlimbs. Murine macrophages and fibroblast-like cells appear responsible for tissue destruction in engrafted and non-engrafted arthritic joints.

Anti-inflammatory effects of systemic anti-tumour necrosis factor alpha treatment in human/murine SCID arthritis

OBJECTIVES

To evaluate in vivo the contribution of tumour necrosis factor alpha (TNFalpha) to the chimeric transfer model of human rheumatoid arthritis synovial membrane into SCID mice (hu/mu SCID arthritis), systemic anti-TNFalpha treatment was performed and the clinical, serological, and histopathological effects of this treatment assessed.

METHODS

Animals were treated with the rat-antimouse TNFalpha monoclonal antibody V1q, starting on day 1 after hu/mu engraftment, twice weekly for 12 weeks. Joint swelling, serum concentrations of human and murine interleukin 6 (IL6), and serum amyloid P (SAP) were measured. Histopathological and immunohistochemical analyses of the joints were also performed at the end of treatment.

RESULTS

Neutralisation of murine TNFalpha induced the following effects: (a) reduction of extent and duration of the acute arthritis phase, with significant reduction of joint swelling at two weeks; (b) decrease of murine SAP concentrations after the first antibody administration; and (c) increase of murine IL6 in the serum. At the end of treatment, there was a significant reduction of the inflammatory infiltration in the engrafted joints. Because of the mild degree of joint erosion, no treatment effects could be demonstrated on the destructive process.

CONCLUSION

In the lymphocyte independent hu/mu SCID arthritis, anti-TNFalpha treatment reduces local and systemic signs of inflammation.

Flexor tendon repair in a rabbit model using a "core" of extensor retinaculum with synovial membrane. An experimental study

In this histological and biomechanical study in two groups of rabbits, a piece of the extensor retinaculum with its synovial membrane was inserted as a biological "core" into a hole at the centre of both stumps of a severed tendon, which was repaired with interrupted sutures. In the other group, the tendon was sutured without a "core". In the "core" group, proliferation and migration of fibroblasts from both tendon surfaces and the "core" surface toward the deep layer of the suture site was seen 2 weeks after operation. New collagen fibres, aligned parallel to the long axis of the tendon, could also be seen 4 weeks after operation, and healing was more advanced than in the coreless model. The maximum force to produce a gap in the "core" tendon was 82% greater than in the coreless tendon 4 weeks after operation.

Treatment of rheumatoid synovitis with anti-reshaping human interleukin-6 receptor monoclonal antibody: use of rheumatoid arthritis tissue implants in the SCID mouse model

OBJECTIVE

To examine the effect of anti-reshaping human interleukin-6 receptor monoclonal antibody (anti-rsHuIL-6R mAb) on patients with rheumatoid arthritis (RA), using SCID mice in which human RA synovial tissue has been grafted (SCID-HuRAg).

METHODS

Tissue from human RA pannus was implanted subcutaneously in the backs of 69 SCID mice. Differences from human RA were examined pathologically. Anti-rsHuIL-6R mAb (100 microg) was administered intraperitoneally to mice once a week for 4 weeks. The implanted tissue was removed from the SCID-HuRAg mice on the fifth week after the initial treatment and examined pathologically. A group of SCID-HuRAg mice treated with control mAb, an auranofin-treated group, and an untreated group were used as controls. A total of 32 mice (8 in each group) were studied.

RESULTS

Histologic characteristics of the implanted tissues in SCID-HuRAg mice were very similar to those of human RA even 2 months after implantation. In addition, the presence of CD4-, CD8-, CD20-, IL-6-, tumor necrosis factor alpha-, tartrate-resistant acid phosphatase (TRAP)-, matrix metalloproteinase 1 (MMP-1)-, and MMP-9-positive cells was confirmed by immunohistochemical staining. A significant decrease in the number of inflammatory cells, MMP-positive cells, and TRAP-positive cells was observed in the anti-rsHuIL-6R mAb treatment group as compared with the control groups.

CONCLUSION

The SCID-HuRAg mouse is a useful model for evaluating the effectiveness of antirheumatic drugs. Anti-rsHuIL-6R mAb may have an antiinflammatory effect on RA synovitis and an inhibitory effect on osteoclasts.

Potential withdrawal of rheumatoid synovium by the induction of apoptosis using a novel in vivo model of rheumatoid arthritis

OBJECTIVE

To investigate whether Fas-mediated apoptosis has potential as a new therapeutic strategy in rheumatoid arthritis (RA) by use of a novel model of RA in which human RA tissue is grafted into SCID mice.

METHODS

Fresh rheumatoid synovial tissue including joint cartilage was grafted subcutaneously into the backs of SCID mice. Six weeks after engraftment, anti-Fas monoclonal antibody was injected intraperitoneally. Time-related apoptotic changes caused by anti-Fas monoclonal antibody in grafted synovium were evaluated by nick end-labeling histochemistry.

RESULTS

Thirty-six hours after the injection, diffuse apoptotic changes were observed in the grafted synovia. Four weeks after the injection, rheumatoid synovial tissue diminished.

CONCLUSION

This is the first report concerning the present effectiveness of anti-Fas monoclonal antibody in diminishing rheumatoid synovium in vivo, and suggests the possibility of a new strategy for treating rheumatoid arthritis by inducing Fas-mediated apoptosis.

Interleukin-4 and interleukin-10 are chondroprotective and decrease mononuclear cell recruitment in human rheumatoid synovium in vivo

We used the severe combined immunodeficient (SCID) mouse model to assess the effect of interleukin-4 (IL-4) or IL-10 injection on cartilage degradation and mononuclear cell (MNC) recruitment to human rheumatoid synovium in vivo. Human rheumatoid synovium and cartilage from five rheumatoid arthritis patients, obtained after joint replacement surgery, were engrafted subcutaneously to 6-8-week-old SCID CB17 mice. Synovial tissues were injected with recombinant human IL-4 (rhIL-4, 100 ng; rhIL-10, 100 ng), both cytokines, or tumour necrosis factor-alpha (TNF-alpha) (1000 U), or phosphate-buffered saline twice a week for 4 weeks. The graft was removed and immunochemical analysis was carried out to assess intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin expression. Moreover, cartilage degradation was assessed through the quantification of the erosion surface on a computerized image of the engrafted cartilage at high power view. MNC recruitment in the synovial tissue was determined by labelling blood MNC with indium-111 before their intraperitoneal injection. The activity obtained in the region of the graft were determined with a gamma camera 72 hr postinjection. The results are expressed as a percentage of initial injected activity. After 4 weeks we observed a decrease of cartilage area in controls (77 +/- 8%), inhibited after injection of IL-4, IL-10, or both cytokines (90 +/- 3%, 89.1 +/- 4%, 89.2 +/- 5% respectively), and 57 +/- 17% after TNF-alpha injection. The % MNC activity in the graft decreased to 77 +/- 81% (NS), 9 +/- 4% (P < 0.003) and 19 +/- 6% (P < 0.007) compared with untreated synovial tissue after treatment with IL-4, IL-10, or both cytokines, respectively. Moreover, IL-10 but not IL-4 decreased the expression of ICAM-1 but not VCAM-1 or E-selectin by synovial cells. These results suggest that IL-10 and IL-4 could have chondroprotective properties, and that IL-10 but not IL-4 inhibits MNC traffic towards the synovial tissue efficiently.

Interleukin 15 is produced by endothelial cells and increases the transendothelial migration of T cells In vitro and in the SCID mouse-human rheumatoid arthritis model In vivo

The capacity of endothelial cells (EC) to produce IL-15 and the capacity of IL-15 to influence transendothelial migration of T cells was examined. Human umbilical vein endothelial cells expressed both IL-15 mRNA and protein. Moreover, endothelial-derived IL-15 enhanced transendothelial migration of T cells as evidenced by the inhibition of this process by blocking monoclonal antibodies to IL-15. IL-15 enhanced transendothelial migration of T cells by activating the binding capacity of the integrin adhesion molecule LFA-1 (CD11a/CD18) and also increased T cell motility. In addition, IL-15 induced expression of the early activation molecule CD69. The importance of IL-15 in regulating migration of T cells in vivo was documented by its capacity to enhance accumulation of adoptively transferred human T cells in rheumatoid arthritis synovial tissue engrafted into immune deficient SCID mice. These results demonstrate that EC produce IL-15 and imply that endothelial IL-15 plays a critical role in stimulation of T cells to extravasate into inflammatory tissue.

Gene transfer to human rheumatoid synovial tissue engrafted in SCID mice

OBJECTIVE

To assess the feasibility of gene therapy in rheumatoid arthritis (RA) and determine the appropriate vector.

METHODS

Human rheumatoid synovial tissue from 6 patients with RA was transduced ex vivo with a recombinant retroviral vector (pMFG.nlsLacZ) containing the Escherichia coli beta-galactosidase (beta-gal) gene in a coculture assay in the presence of 20 ng/ml tumor necrosis factor alpha (TNF-alpha) for promoting cell division. We also conducted in vitro infection experiments using an adenoviral vector (AdCMVSpl.LacZ) containing the beta-gal gene. After gene transduction, the synovial tissue was engrafted subcutaneously in 8-week-old severe combined immunodeficiency (SCID) CB17 mice. Beta-gal expression was then monitored as a function of time (up to 21 days) and of virus dose [up to 50 colony forming units (cfu)/cell]. The efficacy of direct in vivo gene transfer was also tested by injection of 10(6) cfu of pMFG.nlsLacZ into rheumatoid synovial tissue engrafted in SCID mice.

RESULTS

When recombinant retroviral vector was used, 30 +/- 5% of ex vivo infected synovial cells were positive for staining. In synovial tissue implanted in SCID mice, beta-gal expression declined to 5% after one week, but persisted for at least 21 days. Direct injection of pMFG.nlsLacZ vector into the rheumatoid synovial tissue implanted in SCID mice allowed efficient and stable in vivo infection of the synovial tissue. Ex vivo gene transfer with adenoviral vector resulted in a 98% infection rate of the synovial lining cells. However, beta-gal activity declined 7 days after subcutaneous implantation.

CONCLUSION

Highly efficient gene transfer in rheumatoid synovial tissue is achievable with both adenoviral and retroviral vectors, but the results were transient. Exogenous gene transfer through retroviral vectors required stimulation with TNF-alpha for synovial cell division and proviral integration. Direct in vivo gene transfer with recombinant retrovirus was shown to be efficient. Transduction of human synovial tissue engrafted in SCID mice is a potent tool for developing preclinical models of gene therapy in RA.

Myoblast-mediated gene transfer to the joint

Several genetic and acquired pathologic conditions of the musculoskeletal system, such as arthritis and damage to ligament, cartilage, and meniscus, may be amenable to gene therapy. Even though ex vivo gene transfer with synovial cells has been shown to deliver genes encoding for anti-arthritic proteins into the rabbit knee joint, its success has been limited by a transient transgene expression. In this study, data were investigated regarding the use of muscle cells as an alternative gene-delivery vehicle to the joint in newborn rabbit and adult severe combined immunodeficiency mice. We demonstrated that myoblasts were transduced more efficiently than synovial cells with use of the same adenoviral preparation in vitro. After intra-articular injection, the engineered muscle cells adhered to several structures in the joint, including the ligament, capsule, and synovium. In addition, myoblasts fused to form many post-mitotic myotubes and myofibers at different locations of the joint of the newborn rabbit 5 days after the injection. In the knee of the adult mouse, myoblasts fused and expressed the reporter gene for at least 35 days after the injection. The presence of post-mitotic myofibers in the knee joint raises the possibility of long-term expression of the secreted protein. Currently, numerous tissues in the joint (ligament, meniscus, and cartilage) have poor intrinsic healing capacity and frequently need surgical corrections. A stable gene-delivery vehicle to the joint producing proteins that ameliorate these different musculoskeletal conditions may change the clinical implications of these pathologies.

Constitutive intra-articular expression of human IL-1 beta following gene transfer to rabbit synovium produces all major pathologies of human rheumatoid arthritis

To investigate the pathophysiologic effects of chronically elevated intra-articular levels of IL-1 beta, we used an ex vivo gene transfer method to deliver and express human IL-1 beta (hIL-1 beta) in the knee joints of rabbits. Expression of hIL-1 beta resulted in a severe, highly aggressive form of arthritis analogous to chronic rheumatoid arthritis in humans. Intra-articular manifestations included intense inflammation, leukocytosis, synovial hypertrophy and hyperplasia, and highly aggressive pannus formation with erosion of the articular cartilage and periarticular bone. Systemic effects were also observed, including diarrhea, fever, weight loss, and an increased erythrocyte sedimentation rate. In addition, the hIL-1 beta was found to induce elevated levels of both rabbit IL-1 beta and TNF-alpha in synovial fluid. Following the loss of hIL-1 beta transgene expression between 14 and 28 days post-transplantation, many of these changes began to normalize. These results suggest that chronically elevated intra-articular levels of IL-1 beta alone are sufficient to produce virtually all the pathologies found in rheumatoid arthritis, and furthermore, demonstrate that gene transfer can be used to investigate the roles of specific gene products in the pathogenesis of arthritis.

Human IL-1Ra gene transfer into human synovial fibroblasts is chondroprotective

Rheumatoid arthritis (RA) is characterized by progressive destruction of synovial cartilage. In vitro, degradation of cartilage is stimulated by IL-1, a proinflammatory cytokine, which is released from RA synovial fibroblasts (RA-SF). To determine whether gene therapy using the gene encoding the naturally occurring inhibitor of IL-1, IL-1 receptor antagonist (IL-1Ra) is feasible, IL-1 Ra-transduced RA-SF were coimplanted with normal human cartilage in SCID mice. The IL-1 Ra-transduced RA-SF continued to secrete IL-1Ra over a 60-day period. Cartilage that was coimplanted with RA-SF transduced with a marker gene exhibited progressive, chondrocyte-mediated cartilage degradation, whereas no such degradation was observed in cartilage that was coimplanted with RA-SF transduced with IL-1 Ra. Thus, gene therapy using a retrovirus-based gene delivery system appears to be a feasible approach to effectively modifying the local synovial environment.

Free synovium promotes meniscal healing. Synovium, muscle and synthetic mesh compared in dogs

We studied the effect of free synovium on the healing of tears in the avascular portion of the menisci in dogs. A longitudinal incision was made in the medial meniscus. In 35 dogs, a free graft of synovium was inserted into the tear and sutured. In 10 dogs, a free graft of quadriceps muscle was used. In 10 dogs, a Dacron mesh was inserted. In the contralateral knee, the tear was sutured without implantation as a control. 2, 4, 6, 8, and 12 weeks after the operation, the menisci were dissected. 11 of the 35 with free synovium were healed. The menisci with muscle grafts, those with Dacron mesh and those in the control group did not heal. Histology showed that tears were repaired with fibrous tissue. Microangiography showed that capillaries grew from the periphery, but they did not reach the tear.

Synovial fibroblasts of patients with rheumatoid arthritis attach to and invade normal human cartilage when engrafted into SCID mice

Rheumatoid arthritis (RA) has been thought to be largely a T-cell-mediated disease. To evaluate the role of T-cell-independent pathways in RA, we examined the interaction between isolated RA synovial fibroblasts and normal human cartilage engrafted into SCID mice in the absence of T cells and other human cells. The expression of cartilage-de grading enzymes and adhesion molecules was examined by immunohistochemistry and in situ hybridization techniques. The RA synovial fibroblasts invaded the cartilage and kept their transformed appearing cellular shape. They expressed VCAM-1 and produced the cathepsins L and B at the site of invasion. We conclude that RA synovial fibroblasts maintain their invasive and destructive behavior over longer periods of time in the absence of human T cells, indicating that T-cell-independent pathways play a significant role in rheumatoid joint destruction.

Mononuclear cell retention in rheumatoid synovial tissue engrafted in severe combined immunodeficient (SCID) mice is up-regulated by tumour necrosis factor-alpha (TNF-alpha) and mediated through intercellular adhesion molecule-1 (ICAM-1)

The aim of this study was to assess regulation of mononuclear cell (MNC) traffic to human synovial tissue by TNF-alpha and IL-1 and the involvement of ICAM-1 in MNC retention in rheumatoid synovial tissue. Human rheumatoid arthritis synovium was engrafted subcutaneously in 6-8 week-old SCID/CB17 mice. Three weeks later, we injected 20 x 10(6) human peripheral blood mononuclear cells (PBMC) previously labelled with 111indium intraperitoneally into mice containing control or cytokine-injected grafts. Total body scintigraphy was performed 72 h postinjection. The graft was removed and immunochemical analysis carried out to assess ICAM-1, vascular cell adhesion molecule-1 (VCAM-1) and E-selectin expression. In some experiments, mice were treated intravenously with 500 micrograms MoAb anti-ICAM-1 (BIRR-1) or an isotype-matched control MoAb before introduction of MNC. TNF-alpha, but not IL-1 alpha, enhanced MNC retention in the rheumatoid synovial graft 72 h post-injection (graft activity 989 +/- 1227 ct/min per 200 pixels or 3.36 +/- 4.16% of initial injected activity versus 411 +/- 157 ct/min per 200 pixels or 1.13 +/- 0.45% in controls; P < 0.03). TNF-alpha enhanced ICAM-1 expression by synovial cells and endothelial cells, whereas VCAM-1 or E-selectin expression was not enhanced on either cell type. After MoAb treatment of ICAM-1, synovial lymphocyte recruitment of TNF-alpha-treated mice decreased significantly to levels below that of control mice (160 +/- 97 ct/min per 200 pixels, 0.54 +/- 0.33%; P < 0.01). Mononuclear cell retention in rheumatoid synovial tissue engrafted into SCID mice was up-regulated by TNF-alpha and blocked by MoAb to ICAM-1. These results suggest that ICAM-1 is involved in mononuclear cell retention in rheumatoid synovium.

Orthotopic implantation of inflamed synovial tissue from RA patients induces a characteristic arthritis in immunodeficient (SCID) mice

The objective of this work was to study in more detail the human/murine SCID arthritis model with special emphasis on characteristic features initiated by rheumatoid arthritis (RA) synovial membrane (SM) as compared to appropriate control tissues. Small tissue samples from RA-SM, healthy lymph node, healthy SM, and granulomatous tissue of human origin were implanted into the left knee joint of mice with severe combined immunodeficiency (SCID), and the joints were analysed histologically after 7 days. In addition, a time course study, including non-invasive monitoring by serological parameters (human IgM, IgG, and IL-6) and Tc-99m-scintigraphy, was performed for up to 4 weeks on RA-SM recipients. All tissue implants induced transient exudative joint inflammation while RA-SM initiated a characteristic arthritis with pannus tissue of high cellular density, erosion, multinuclear giant cells, lining cell hyperplasia, fibroblast-like cell layers, chondroideal metaplasia, and fibrin deposits. Significantly elevated levels of human immunoglobulin and characteristic signs of chronic inflammation persisted for more than 4 weeks. We conclude that the hu/mu SCID arthritis with RA-SM implants comprises features of non-specific inflammation which is also transiently seen with control tissues but develops characteristic features of chronic RA-like synovitis thereafter.

In vivo migration of radiolabelled lymphocytes in rheumatoid synovial tissue engrafted in SCID mice: implication of beta 2 and beta 7-integrin

OBJECTIVE

Integrin-adressin binding is a critical step in lymphocyte attachment to target tissues. The lymphocyte function associated antigen (LFA-1)/intercellular adhesion molecule-1 (ICAM-1) pathway has been shown to be involved in the homing of lymphocytes to arthritic joints in animal models. The mucosal recognition system [alpha E beta 7/E-cadherin, alpha 4 beta 7/mucosal vascular adressin cellular adhesion molecule 1 (MADCAM-1)] has been implicated in the autoimmune process of nonobese diabetic mice and in rheumatoid arthritis (RA). We developed a model for in vivo study of radiolabelled lymphocyte circulation and attachment to human engrafted rheumatoid synovium, and studied the involvement of LFA-1 and alpha E beta 7 integrin.

METHODS

We engrafted human RA or osteoarthritis (OA) synovium subcutaneously in 6-week-old SCID/CB17 mice. Three weeks later, we injected intraperitoneally 20 x 10(6) human peripheral blood lymphocytes (PBL) labelled with 3 mCi 99mtechnetium hexamethyl propylenamine oxime. A mouse total body scintigraphy was obtained 20 h postinjection. The same protocol was performed after pretreatment of the PBL with monoclonal antibodies (Mab) against CD11a (25-3) or against alpha E beta 7 human mucosyl lymphocyte marker 1.

RESULTS

PBL migrated in the rheumatoid synovial graft 20 h postinjection (activity in the region of interest of the graft: 7699 +/- 4383 cpm/200 pixel or 4.43 +/- 2.65% of initial activity) versus OA engrafted synovial tissue (1453 +/- 1137 or 0.74 +/- 0.6% of initial activity), p = 0.007. The homing to the engrafted rheumatoid synovial tissue of PBL from healthy subjects was not significantly different from the migration of PBL from patients with RA. A Mab against alpha E beta 7 significantly decreased lymphocyte attachment to rheumatoid synovial tissue (3094 +/- 3808 cpm/200 pixel or 2.65 +/- 2.4% of injected activity), p < 0.03. The same results were obtained with Mab against CD11a (5007 +/- 4190 cpm/200 pixel or 2.27 +/- 1.2%), p < 0.01. Our results show increased blood lymphocytes homing to rheumatoid synovial tissue engrafted in SCID mice versus OA tissue.

CONCLUSION

The data suggest that both LFA-1 and mucosal recognition integrin alpha E beta 7 are involved in lymphocyte binding to target tissues in RA.