Engineered M2a macrophages for the treatment of osteoarthritis

Abstract

BackgroundMacrophage is a central regulator of innate immunity. Its M2 subsets, such as interstitial synovial macrophages, have been found to play critical roles in suppressing chronic inflammation and maintaining homeostasis within the joint. These macrophages have great potential as a disease-modifying cell therapy for osteoarthritis (OA). However, this has not yet been studied.MethodsMacrophages were isolated from the bone marrow of rats. We constructed a stable macrophage that “locked” in anti-inflammatory and pro-regenerative M2a polarity (L-M2a) by simultaneously knocking out tumor necrosis factor receptor 1 (TNFR1) and overexpressing IL-4 using Cas9-ribonuclear proteins (Cas9-RNP) and electroporation. In vitro, these L-M2a macrophages were treated with OA synovial fluid or co-cultured with OA chondrocytes or fibroblast-like synoviocytes (FLS). In vivo, L-M2a macrophages were injected intra-articularly to evaluate their homing and engrafting abilities and therapeutic effects on OA progression using a rat model.ResultsL-M2a macrophages displayed a typical anti-inflammatory phenotype similar to that of M2 macrophages in vitro. In OA microenvironment, L-M2a macrophages maintained a stable anti-inflammatory phenotype, whereas unmodified M2 macrophages lost their phenotype and switched to M1 polarity. L-M2a macrophages demonstrated a potent anti-inflammatory effect in crosstalk with OA-FLSs and an anti-degenerative effect in crosstalk with senescent OA chondrocytes. In vivo, compared with M2 macrophages and exosomes, L-M2a macrophages exhibited significantly superior therapeutic effects in OA by successfully resolving inflammation, restoring tissue homeostasis, and promoting cartilage regeneration.ConclusionThe engineered L-M2a macrophages maintained a superior anti-inflammatory and pro-regenerative capacity in the inflammatory OA microenvironment and represents an ideal new strategy for the disease-modifying therapy of OA.

Use of the improved tug-of-war acupuncture for promoting cartilage repair by inducing macrophage polarization in knee osteoarthritis

“…In contrast, M2 macrophages induced by IL-4 and IL-13 upregulate the expression of genes related to wound healing and participate in anti-inflammatory response [ 29 ]. Pro-inflammatory and anti-inflammatory macrophage dysfunction could lead to chronic inflammation and play an important role in chronic inflammatory diseases including osteoarthritis [ 30 ]. In our study, based on the ELISA results, BHZF could reduce the levels of inflammatory factors (IL-1β and TNF-α) and increase the levels of anti-inflammatory factors IL-4 and IL-10 in the serum and synovial fluid of rabbits with KOA.…”

Emerging Roles of Macrophage Polarization in Osteoarthritis: Mechanisms and Therapeutic Strategies

“…Therefore, Liang et al . (2022) created a stable exogenous macrophage model by knocking out tumor necrosis factor receptor 1 (TNFR1) and using Cas9‐ribonuclear protein (Cas9‐RNP) complexes and electroporation to overexpress IL‐4, thus locking the interstitial synovial macrophage in the M2a phenotype (L‐M2a) 214 . Similarly, the modified L‐M2a macrophages retained a superior anti‐inflammatory and pro‐regenerative capacity in the inflammatory OA microenvironment, thus representing an ideal new strategy for the disease‐modifying therapy of OA.…”

The Dual Role of Small Extracellular Vesicles in Joint Osteoarthritis: Their Global and Non-Coding Regulatory RNA Molecule-Based Pathogenic and Therapeutic Effects

“…Regarding synovial macrophages, it has been shown that rat BMSCs-sEVs can promote the transformation of macrophages from M1 to M2 type, thereby promoting the secretion of IL-10 but inhibiting IL-1β and TNF-α via synovial macrophages [62,97]. In addition, co-culturing sEV-treated M2-polarized macrophages with chondrocytes also helps maintain the cartilage characteristics of chondrocytes and inhibit their hypertrophy and senescence [97,98] (Figure 1).…”