June 15th, 2026
Today's open access paper combines a few interesting topics. Firstly, the researchers involved describe a way to deliver a short-lived messenger RNA gene therapy selectively to the innate immune cells known as macrophages. Macrophages are normally responsible for engulfing all sorts of unwanted structures in the cell, and many of the specific features that induce that behavior have been identified. Encapsulating messenger RNA into lipid nanoparticles that mimic some of the surface features of cells undergoing programmed cell death results in aggressive uptake by macrophages. Macrophages arguably make a good target for gene therapies in which the goal is to manufacture a secreted molecule of some sort, such as an antibody, and have it fairly widely and evenly distributed throughout the body. For many secreted molecules, this is quite unnecessary; injecting a single subcutaneous fat depot with a small amount of a non-targeted vector can and does work. Distribution in the body is enough of a challenge in gene therapy for any and all alternatives to be welcomed, however.
The application of this novel approach to messenger RNA therapy is in this case a reduction of circulating MMP9. The secreted molecule generated by the targeted macrophages is an anti-MMP9 antibody, directly binding to and allowing clearance of MMP9. Increased circulating MMP9 is characteristic of aging, and here researchers demonstrate that it is the cause of further issues by clearing it and observing benefits. Targeted depletion of MMP9 from circulation achieved via this antibody manufacturing approach improved the function and structure of bone and cartilage tissue in treated mice. It is of course a long road from preclinical proof of concept to therapy in the clinic, and many such demonstrations are never further developed. One might hope that this will at least attract more attention to the production of novel drugs that can much more effectively and selectively reduce circulating MMP9 than is the case for present small molecule drugs known to affect MMP9 levels.
