A Culture Engineering Strategy to Enhance the Therapeutic Efficacy of Mesenchymal Stromal Cells for the Treatment of Osteoarthritis

Robb, Kevin P 1 ; Bhatt, Shashank 2 ; Gómez-Aristizábal, Alejandro 1, 2 ; Gandhi, Rajiv 2, 3 ; Viswanathan, Sowmya 1, 2, 4;

1.  Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2.  The Arthritis Program, Krembil Research Institute, University Health Network, Toronto, Canada; 3.  Division of Orthopaedic Surgery, Toronto Western Hospital, University of Toronto; 4.  Cell Therapy Program, University Health Network, Toronto, Canada

Introduction: Osteoarthritis (OA) is a debilitating disease involving progressive cartilage degradation linked to chronic inflammation and metabolic dysregulation within the joint. Mesenchymal stromal cells (MSCs), including those from adipose tissue (AT-MSCs) are promising as a therapy [1]; however, insufficient in vivo potency and donor variability can limit their therapeutic efficacy [2]. To address this, the Viswanathan lab has pioneered a proprietary culture engineering strategy to enhance MSC potency by augmenting anti-inflammatory and immunomodulatory functions (US62/397,572).

Objective: The ability of culture engineered AT-MSCs (ce-AT-MSCs) to reduce inflammation, fibrosis, and cartilage degradation will be assessed relative to unprimed naïve MSCs (nAT-MSCs) within in vitro and in vivo OA models.

Methods: Human AT-MSCs or bone marrow MSCs (BM-MSCs) were subject to a proprietary engineering culture protocol (US62/397,572) or standard culture conditions. MSC cell surface markers and multipotent differentiation capacity was verified by flow cytometry and histology. Flow cytometry was used to assess the effects of MSCs on activated T helper (Th) cell proliferation, as well as the expression of monocyte/macrophage phenotypic markers in direct co-cultures with MSCs. qPCR was performed to examine expression of OA-related genes in ceMSCs and nMSC controls.

Results: Initial studies focused on the use of BM-MSCs and showed that both ceBM-MSCs and nBM-MSCs expressed characteristic cell surface markers and displayed multipotent differentiation capacity, thereby satisfying MSC criteria [3]. When cultured in pooled human OA synovial fluid (SF) to partially simulate the extracellular OA microenvironment, ceBM-MSCs significantly reduced activated Th cell proliferation relative to nBM-MSCs. Preliminary investigation of MSCs sourced from adipose tissue revealed that ceAT-MSCs showed increased expression of a panel of anti-inflammatory and immunomodulatory genes implicated in OA relative to controls, suggestive of their improved potency in the context of treating OA.

Discussion: ceMSCs have enhanced anti-inflammatory and immunomodulatory characteristics and may therefore be a promising cell-based therapy for OA. Ongoing studies will focus primarily on MSCs sourced from adipose tissue as a clinically translational and easily accessible cell source for OA treatment. Specifically, we will investigate interactions between ceAT-MSCs and joint synovial cells, and evaluate the regenerative mechanisms of action in tissue explant and mouse models of the disease. Taken together, these studies will aid in the development of improved-efficacy MSCs as an OA therapeutic. [1] Pers, YM et al. Stem Cells Transl Med 5(7):847-56 (2016) [2] Diekman, BO et al. Curr Opin Rheumatol 25(1):119-26 (2013) [3] Dominici, M et al. Cytotherapy 8(4):315-7 (2006)