Rapid 48-hour inflammation-resolving polarization of monocytes/macrophages is feasible at larger scale and shows anabolic effect in human osteoarthritic joint explant model

Abstract

Background & Aim Monocytes/macrophages (MΦs, as a heterogeneous population) exist on a pro-inflammatory to pro-resolving spectrum. Endogenous polarization maintains tissue homeostasis but dysfunctionally perpetuates disease states in chronic inflammation. Exogenous cytokines can also polarize MΦs. This has allowed clinical trial manufacturing of MΦ subsets under the pro-resolving umbrella for indications such as liver cirrhosis and renal transplant. These approaches require 5-to-7-day processing. We have developed a pro-resolving MΦ polarization protocol that takes 48 hours and scales to higher culture volumes. We will test the role of polarized MΦs in osteoarthritis (OA). Inflammation is a contributor to OA progression, with a central role for pro-inflammatory MΦs, as we have previously demonstrated. We will evaluate potential therapeutic effects of pro-resolving MΦs on inflammation and cartilage loss in a human joint model that mimics OA processes. Methods, Results & Conclusion CD14+ cells (MΦs) are obtained from peripheral whole blood or leukapheresis via manual or automated immunomagnetic isolation using the CliniMACS Prodigy. MΦs are polarized in either 1 mL in a 24-well plate or 1000 mL in a MACS GMP Cell Differentiation bag using IL-10+TGF-β1 (pro-resolving). Control groups are naive and IFN-γ+LPS (pro-inflammatory) MΦs. MΦs are characterized by surface markers, gene expression, endocytosis, reactive oxygen species production, and Treg induction. Polarized MΦs are then co-cultured with OA cartilage-synovium explants from arthroplasty for 48 hours. Cartilage and culture media are measured for gene expression and secreted proteins. Surface marker expression of pro-resolving MΦs is comparable at plate and bag scales, demonstrating an expected CD163hi/HLA-DRlo/CD86neg profile with gene expression of IL-10. Surface markers are maintained after pro-inflammatory explant co-culture, confirming stability of this approach. Ongoing tests will confirm pro-resolving functional properties. Importantly, pro-resolving MΦs upregulate OA cartilage expression of anabolic matrix genes (such as lubricin and protease inhibitor TIMP1) and secreted proteins. Our rapid pro-resolving MΦ polarization method eases translation into potent, cost-effective cell therapy products. It is functional, scalable, and allows modulation of input; we are currently screening small molecules as an alternative to cytokines. In parallel with our murine OA studies, our results support proof-of-concept towards a feasible MΦ-based therapy for OA.