Purpose

TG‑C is a cell-mediated gene therapy for the treatment of knee osteoarthritis (OA). In this preclinical study we employed rats and goats to demonstrate the pre-clinical safety of TG-C.

Methods and Materials

All animal studies were conducted with ethical committee permission and approval and in line with the World Medical Association (WMA) Declaration of Helsinki and NC3Rs ARRIVE guidelines to ensure the welfare of animals used for research. 2x10⁶ / ml (20 μl) TG-C cells (48Gy-irradiated) were injected into the knee joints of 70 (35 male and 35 female) Sprague-Dawley (SD) rats. Quantitative PCR (qPCR) was used to detect human cells and RvTGFβ1 vector-transduced cells. Safety studies in goats examined a total of 71 animals. Goats received high and low doses of TG-C; 10 animals received a high single-dose of 5x10⁷ cells/ml (500 μl); 10 animals received a low dose single-dose of 1x10⁷ cells/ml (500 μl); 10 animals received a high multiple-dose 5x10⁷ cells/ml (500 μl) and were followed up for 6 and 12 months.

Results

Real-time qPCR was performed to determine if human TG-C cells can be detected the knee joints and other organs. Treatment with TG-C had no effect on mortality, body weight, or gross or microscopic pathology of the injection site in rats. Safety studies in goats revealed no adverse findings, either systemically or locally at the 6 or 12-month timepoints. TG-C was well tolerated and did not elicit any immune responses in the goats either in the low, high, single or multiple doses.

Conclusion

The radiation inactivation of cell proliferation in the GP2-293 component of TG C underlines the suitability for intra-articular injection into the knee joint. The introduction of a gamma or x-ray radiation inactivation step in the preclinical development pipeline for TG-C highlights the utility of this approach for developing other cell-based approaches for the intra-articular treatment of OA.

Introduction

Osteoarthritis (OA) is the most common form of arthritis globally. The degradation and loss of articular cartilage is one of the classical hallmarkrs of OA. Although cartilage destruction is a central feature of OA, synovial inflammation, subchondral bone remodelling and osteophyte development are also important features of the disease. Therefore, in addition to its adverse effects on cartilage, OA can also negatively impact on all the tissues of the joint, including sub-chondral bone, peri-articular ligaments, and skeletal muscle. Symptoms of OA include pain and inflammation in the joints, resulting in reduced mobility, diminished quality of life and long-term disability. OA is increasingly considered a serious, chronic disease and other than joint replacement surgery there is presently no cure. Existing pharmacological medications can provide symptomatic relief, but their effects on the progression of the disease are limited. The lack of effective treatments for OA create exciting opportunities for developing innovative new approaches for cartilage repair and joint preservation. Protection using intra-articular injections of cells, biologicals and biomaterials, including hydrogels is receiving increasing attention. This presentation will focus on recent advances and opportunities for cartilage repair using cell-based gene therapy, viral vector-based gene therapy and biomaterials, including hydrogels. This presentation will also discuss how emerging innovations in biotechnology can impact on the field of OA research and cartilage repair.

Content

The recently published literature will be reviewed with a special focus on intra-articular treatments that incorporate cell-based and viral vector-based gene therapy (Mobasheri 2020; Mobasheri et al., 2020; Uzieliene et al., 2021). Cell-based and viral vector-based gene therapy have the potential to transform the development of new therapeutics for joint disease and are already tested in preclinical animal modesl and human clionical trials. Treatments that incorporate intra-articular injections can potentially combine hydrogels, cells and biologicals creating combination products. The development of a new generation of innovative disease-modifying therapeutics is a high priority for OA and other joint diseases. Biomaterials, hydrogels, viral, non-viral and cell-based gene delivery technologies have the potential to transform orthopaedics and rheumatology. Further research is needed to optimize the transfection efficiency, longevity and duration of gene expression in gene therapy. More research is also needed to understand the mode of action of injectable hydrogels. The development of disease-modifying therapeutics for OA has recently suffered a number of high-profile setbacks. However, there are opportunities for multidisciplinary collaboration to drive new innovation. These approaches can also positively impact on the field of cartilage repair for facilitating the repair of focal cartilage lesions.

References

1. Mobasheri A. Future Cell and Gene Therapy for Osteoarthritis (OA): Potential for Using Mammalian Protein Production Platforms, Irradiated and Transfected Protein Packaging Cell Lines for Over-Production of Therapeutic Proteins and Growth Factors. Adv Exp Med Biol. 2020;1247:17-31. doi: 10.1007/5584_2019_457.

2. Mobasheri A, Choi H, Martín-Vasallo P. Over-Production of Therapeutic Growth Factors for Articular Cartilage Regeneration by Protein Production Platforms and Protein Packaging Cell Lines. Biology (Basel). 2020 Oct 9;9(10):330. doi: 10.3390/biology9100330.

3. Uzieliene I, Kalvaityte U, Bernotiene E, Mobasheri A. Non-viral Gene Therapy for Osteoarthritis. Front Bioeng Biotechnol. 2021 Jan 13;8:618399. doi: 10.3389/fbioe.2020.618399.

Acknowledgments

I would like to thank colleagues and collaborators at Kolon TissueGene (Rockville, MD, United States), Flexion Therapeutics (Burlington, MA, United States) and Hy2Care B.V. (Enschede, the Netherlands).