Human FGF18 mRNA

Fibroblast growth factor 18 (FGF18) is a promising therapeutic target for osteoarthritis (OA). Here, researchers developed a novel articular cavity-localized lipid nanoparticle (LNP), named WG-PL14. Compared with the commercially available lipids MC3, this optimized formulation increased mRNA expression by nearly 30 times when injected into the joint cavity, and had better joint cavity enrichment. Subsequently, the mRNA sequence encoding recombinant human FGF18 (rhFGF18) was optimized for potential mRNA therapy of OA. In vitro experiments confirmed that rhFGF18 mRNA was translated into functional protein in rat and human chondrocytes, promoting cell proliferation and extracellular matrix (ECM) synthesis. Subsequently, the therapeutic effect of LNP-rhFGF18 mRNA complex was systematically evaluated in a mouse OA model. Compared with the control group, the therapy showed multiple positive effects, including improved pain response, upregulated expression of extracellular matrix-related genes (such as AGRN and HAS2), and remodeling of subchondral bone homeostasis. Taken together, these findings highlight the potential of local LNP-rhFGF18 mRNA therapy in promoting cartilage tissue regeneration and slowing the progression of OA.

To evaluate the transfection efficiency of rat chondrocytes, the researchers first transfected EGFP mRNA into the cells. Confocal microscopy imaging showed that EGFP mRNA emitted strong green fluorescence compared with the control group (Figure 1A). Fluorescence-activated cell sorting (FACS) analysis showed that the EGFP signal in the transfected group was enhanced 10 times (Figure 1B). Further statistical analysis confirmed that 92.3% of rat chondrocytes were successfully transfected with EGFP mRNA (Figure 1C). The above results show that the transfection efficiency of mRNA in rat chondrocytes is high by chemical transfection, which provides a suitable method for introducing rhFGF18 mRNA into rat chondrocytes. Next, to evaluate the biological function of rhFGF18 mRNA, the researchers used the above method to transfect rhFGF18 mRNA into rat chondrocytes. FGF18 immunostaining showed that rhFGF18 was widely expressed in the cytoplasm (Figure 1D), and the fluorescence intensity difference between the control group and the transfected group was significant (Figure 1E). Western Blot also verified the expression of rhFGF18 in rat chondrocytes (Figure 1F). In addition, rhFGF18 could be detected in the supernatant (Figure 1G). These results indicate that in vitro transcribed rhFGF18 mRNA can be translated into rhFGF18 protein and is correctly secreted by rat chondrocytes.

Figure 1. In vitro transfection and characterization of GFP and rhFGF18 mRNA. (Sun M, et al., 2024)