No, but many (most? all?) of the symptoms could be due to brain cells not doing their job properly. Heart failure doesn't kill you; it's the failure of the brain due to lack of blood flow that ends your life. Lack of blood flow, or low oxygen, would be a biomarker for that, but that's far easier to detect than the failure of possibly just a few brain cells whose dysfunction causes serious symptoms elsewhere in the body.
I was going to say "effects" rather than "symptoms", but so far they haven't found any clear markers of physical effects in the body. Some PWME can't get out of bed, but there's no apparent physical cause (muscle metabolism or whatever), but that doesn't rule out a malfunction in the control circuitry in the brain. We don't have the technology to readily identify that sort of malfunction, and it probably wouldn't show up in spinal fluid. One transistor failing in a CPU can crash your computer, but measuring the supply voltage or current isn't going to reveal that (one transistor out of billions, switching at GHz frequency). The marker is there, it's just buried in too much noise to be practical to dig out.
So yes, there might be some physical measurements of collagen, muscles, capillaries, etc, that are due to ME, but it's buried in too much noise and too far removed from the core dysfunction to be useful.
That's why I favour the black box approach: vary some inputs and hopefully find something that causes a reliable response in ME symptoms. If someone had studied my body when I had a reliable way (cuminaldehyde) to switch my PEM off, that might have revealed something. Dynamic abnormalities are much easier to identify than static ones, especially when they are weak abnormalities in a lot of noise, and what's "normal" varies a lot between individuals.