Clinical trial to assess the safety, feasibility, and efficacy of transferring a potentially anti-arthritic cytokine gene to human joints with rheumatoid arthritis

Direct adenovirus-mediated gene transfer of interleukin 1 and tumor necrosis factor alpha soluble receptors to rabbit knees with experimental arthritis has local and distal anti-arthritic effects

Adenoviral vectors were used to deliver genes encoding a soluble interleukin 1 (IL-1)-type I receptor-IgG fusion protein and/or a soluble type I tumor necrosis factor alpha (TNFalpha) receptor-IgG fusion protein directly to the knees of rabbits with antigen-induced arthritis. When tested individually, knees receiving the soluble IL-1 receptor had significantly reduced cartilage matrix degradation and white blood cell infiltration into the joint space. Delivery of the soluble TNFalpha receptor was less effective, having only a moderate effect on white blood cell infiltration and no effect on cartilage breakdown. When both soluble receptors were used together, there was a greater inhibition of white blood cell infiltration and cartilage breakdown with a considerable reduction of synovitis. Interestingly, anti-arthritic effects were also seen in contralateral control knees receiving only a marker gene, suggesting that sustained local inhibition of disease activity in one joint may confer an anti-arthritic effect on other joints. These results suggest that local intra-articular gene transfer could be used to treat systemic polyarticular arthritides.

The Human Genome Project: implications for the treatment of musculoskeletal disease

The ultimate goal of the Human Genome Project is the determination of the molecular sequence of the entire human chromosomal complement. Realization of this goal will include characterization of all the genes that cause or predispose to disease, which will most certainly lead to the development of powerful new tools for diagnosis, prevention, and treatment in all medical fields, including orthopaedics. The authors review the fundamentals of human genetics and gene mapping, summarize the progress of the Human Genome Project thus far, and discuss the implications of this research as it relates to the treatment of musculoskeletal diseases.

In vivo suppression of early experimental osteoarthritis by interleukin-1 receptor antagonist using gene therapy

OBJECTIVE

This study explored the therapeutic effect of interleukin-1 receptor antagonist (IL-1Ra), administered by gene transfer, on the progression of osteoarthritic (OA) lesions in an experimental dog model.

METHODS

Seventeen mature mongrel dogs were divided into 3 groups. Group 1 (n = 7) had an anterior cruciate ligament (ACL) section of the right knee through a stab wound incision. Groups 2 and 3 (n = 5 per group), had an ACL section of the right knee and partial synovectomy of the left knee. Each dog's synovium was subjected to enzymatic digestion, and the synovial fibroblasts were propagated in monolayer culture. Synovial cells from each dog were transduced in vitro using the retrovirus MFG with either the Escherichia coli beta-galactosidase (lac Z) gene (group 2) or the human IL-1Ra gene (group 3). Two days after surgery, the dogs received intraarticular injections as follows: group 1 phosphate buffered saline (PBS) (2 ml); group 2 autologous cells (60 x 10(6) cells/2 ml of PBS) transduced with the lac Z gene; group 3 autologous cells transduced with the IL-1Ra gene. Synovial fluid was aspirated at 2 weeks and 4 weeks. All dogs were euthanized at 4 weeks postsurgery. The right knees were dissected, and lesions were scored for macroscopic and microscopic changes. Synovial explants were dissected and representative specimens were used for histology or were cultured for 48 hours. The levels of IL-1Ra in synovial fluid and synovial explant conditioned medium were measured by specific enzyme-linked immunosorbent assay.

RESULTS

The level of IL-1Ra in synovial fluid of group 3 was 202.8 +/- 131.5 ng/ml (mean +/- SEM) at 2 weeks and 2.8 +/- 2.2 ng/ml at 4 weeks after surgery. Membrane explants isolated from dogs that received synovial cells transduced with the IL-1Ra gene (group 3) actively produced IL-1Ra (4.0 +/- 2.0 ng/gm of tissue wet weight). The severity of OA cartilage lesions was similar in groups 1 and 2. In contrast, group 3 dogs had a marked reduction in macroscopic lesion severity on the tibial plateaus (P < 0.01 for grade; P < 0.04 for size) and femoral condyles. Moreover, the histologic lesion severity was decreased on both plateaus (P < 0.06) and condyles.

CONCLUSION

This study showed that a local increase in IL-1Ra production in OA knee joints by intraarticular injection of transduced synovial cells can reduce the progression of experimentally induced lesions.

Pathogenesis and treatment of osteoarthritis

OA represents the final common pathway of a number of pathologic processes. The challenge is to define and classify the subsets of OA to understand the causes and to devise specific therapies. Effective chondroprotective therapies will be most useful when applied to high-risk individuals before the emergence of symptomatic OA. This will be feasible only with an improved understanding of the complex interaction of genes and environment in the OA disease process. Moreover, identifying the heritable bases of this disease will provide insight into the molecular mechanisms of the complex pathway that results in OA. Clinicians who encounter and treat OA patients can look forward to the development of more effective and innovative therapies based on a rapidly improving understanding of OA.

Prospects for gene therapy in sports medicine

For the orthopedic sports medicine physician soft tissue injuries often present the greatest clinical problems. Not only do many of the most frequently injured tissues, such as the cruciate ligaments and articular cartilage, have very limited capabilities for spontaneous repair, but they also respond poorly to surgical or nonsurgical intervention. In this article we try to define the role of growth factors in these conditions and to outline concepts for future treatment based upon modulation of the native repair response. We suggest that gene transfer could improve the management of such injuries, particularly when used as vehicles for the targeted delivery of growth factors. The concept of gene therapy in orthopedic sports medicine can be extended to include disorders that present as laxity or mechanical weakness of ligaments. We speculate that subtle genetic differences between individuals may account for those who appear to be injury prone. In these cases it is likely that genes encoding the structural macromolecules of the matrix are defective. Local gene supplementation in such cases could be useful in the future.