Development of an advanced cell therapy product indicated for the treatment of gonarthrosis

Background Gonarthrosis is the most common cause of pain and disability in middle-aged and elderly people [1,2]. The lack of long-lasting effective treatments for repairing degenerated articular cartilage has spurred research into novel cell-based therapies aiming at reducing pain, slowing the degeneration of cartilage and, ultimately, reverting the natural history of osteoarthritis (OA) [3]. Herein we report the development of a mesenchymal stromal cell (MSC)-based therapy, from conception up to completion of a Phase I/IIa prospective, open-label, single-dose, single-arm clinical trial.


Background
Gonarthrosis is the most common cause of pain and disability in middle-aged and elderly people [1,2]. The lack of long-lasting effective treatments for repairing degenerated articular cartilage has spurred research into novel cell-based therapies aiming at reducing pain, slowing the degeneration of cartilage and, ultimately, reverting the natural history of osteoarthritis (OA) [3]. Herein we report the development of a mesenchymal stromal cell (MSC)-based therapy, from conception up to completion of a Phase I/IIa prospective, open-label, single-dose, single-arm clinical trial.

Materials and methods
All animal care and experimental procedures adhered to the recommendations of local, national, and European laws and were approved by the appropriate Ethical Committees on Human and Animal Experimentation.
A GMP-compliant bioprocess was designed for the production of the investigational cell-based medicinal product. Characterisation of MSC adhered to the minimal criteria established by the International Society for Cellular Therapy [4].

Results and discussion
Along the development programme, Good Scientific Practice (GxP) quality standards were implemented gradually in our laboratory ( Figure 1) [12].
The preclinical package included a proof-of-principle study in a large animal model of chronic OA and three regulatory preclinical studies in murine animal models ( Table 1 Figure 1). The intra-articular injection of autologous MSC was safe, as judged by the lack of local or systemic adverse effects and evidence of regeneration of articular cartilage and meniscus was found in specific macroscopic and histological parameters [13]. Three further regulatory preclinical studies were performed in murine animal models in order to 1) assess subchronic toxicology, 2) analyse the biodistribution of human MSC, and 3) investigate dose:response relationship. Our results highlighted the safety of MSC either administered intraarticularly (up to 6x105MSC/knee in rats) or intravenously (IV, 1.3x107 MSC/kg in mice) and the persistence of IV-infused MSC in liver, kidney and spleen, at 3 months post-administration. No tumours were detected in any of the animals during the observation period. IV transplanted hMSC were principally found in the liver, kidneys and spleen of immunocompromised mice. The lungs, in spite of receiving a considerable number of cells immediately after administration, did not appear to be a welcoming environment adequate for MSC survival, thus confirming other author's observations [14]. Previous data in large translational animal models [15], and investigations on the role of MSC in cartilage [16,17] and bone [18] regeneration, provided further support with respect to the safety and regenerative qualities of MSC.
For the clinical testing in humans, the drug product consisted in 40.9x106 ± 0.4x106 viable MSC in 10.0 ± 0.3 mL of saline solution. The phenotypic characteristics of the human MSC used in the study were 99.7% ± 0.2% CD45-CD105+, 99.0% ± 0.6% CD31-CD73+, 99.9 ± 0.3% CD90 and 15.5% ± 14.8 HLA-DR+. The combination of differentiation assays, growth profiles, morphology assessment and cytometric phenotype confirmed the MSC nature of the cells used in our studies. MSC suspensions tested negative for bacteria, mycoplasma and endotoxin before infusion into humans. The analgesic effect of the intra-articular infusion of MSC

Conclusions
We successfully designed and executed a reproducible GMP-compliant bioprocess for the manufacture of cellbased therapeutics. The clinical procedure involved a minimally invasive intervention, which was feasible and safe, resulting in pain relief and preventing further degeneration of articular cartilage.