A Novel Approach to Measuring Macrophage-Specific Reverse Cholesterol Transport In Vivo in Humans

The “reverse cholesterol transport” pathway — by which the body ferries cholesterol out of artery-wall macrophages and excretes it — has long been hypothesized to be protective, but measuring it directly in living people was nearly impossible. This study built a method to do so.

The investigators developed radiolabeled cholesterol nanoparticles that selectively target macrophages, allowing them to track cholesterol’s journey from those cells to HDL and out through the feces, in both mice and humans. It worked as a feasibility demonstration, validating a tool to quantify a process that until then could only be inferred.

This is methods-development science. Its value is enabling future research — a way to test whether therapies that boost reverse cholesterol transport actually do so, and whether that translates to benefit. It is a means, not an endpoint.

We rate the evidence moderate. As a feasibility study in 30 subjects it is preliminary by nature, but it is technically sophisticated and opens a path to studying HDL function more rigorously than the much-criticized HDL-cholesterol number allows.