A cell's resources depend on its surroundings

# A cell's resources depend on its surroundings OCTOBER 17, 2026 Taking a precursor of NAD+ may not be enough if the surrounding tissue is busy breaking it down. A new preclinical study suggests that is what happens in aging bone marrow, where immune cells appear to use up the raw material that bone-building cells need. The species is not named in the abstract; Lifespan.io, which covered the study, describes the work as done in mice. Aging cells inhabit changing neighborhoods. This preclinical work asks how the bone-marrow environment affects the availability of material that bone-building cells need. The work is by Li and colleagues, published in 2026 in the journal Advanced Science. It is preclinical research, meaning lab and animal models, not a trial in people. Only the study's abstract was available to us, and it does not state how many animals were used. Lifespan.io calls the study small. Some background helps. Bone is constantly rebuilt. Bone marrow mesenchymal stem cells can become bone-forming cells, but with age the marrow fills with fat cells and inflammation. NAD+ is a molecule cells use in energy production. NMN is a building block cells use to make it. According to the abstract, the chain starts with fat cells that accumulate in marrow. They release a protein called soluble DPP4. This protein acts on a receptor, TLR4, on marrow macrophages, a type of immune cell. Working together with the macrophages' own mitochondrial DNA, it switches on an inflammatory pathway called STING. The authors report that STING activation raises an enzyme called CD38. This increases inflammation. It also breaks down NMN outside the cells. That leaves less NMN for neighboring stem cells, which the authors say reduces their capacity to form bone. The timing matters. The abstract says that removing STING from these macrophages was harmful during early bone development and maturation. From middle age onward, though, it protected against age-related bone loss. The authors call this an age-dependent dual role. The authors then combined a drug that blocks STING with NMN supplementation. They report that this attenuated bone loss in preclinical models. According to Lifespan.io, the STING blocker was H-151, given to mice from 12 to 18 months of age. Lifespan.io also reports that bone improvements were largely similar to those from alendronate, an established osteoporosis drug used as a comparison. What does this mean for people taking NAD+ boosters? That is interpretation, not a finding. If the marrow environment destroys NMN, a supplement alone may do less there than hoped. Lifespan.io reports that NMN only partly restored energy production in old bone-precursor cells, and did so less well next to old or activated macrophages. The abstract does not say how NMN alone performed in the animal experiments. The limits are clear. Lifespan.io notes the small size and says that combining two treatments makes it hard to separate the effect of STING blocking from that of NMN. No human data were reported, so the findings give no basis for changing supplement or osteoporosis treatment. Readers should not start or stop any medication or supplement without talking to their clinician. The next thing to watch is whether STING blockers, tested alone and alongside NMN, hold up in larger studies and in early human trials. The interaction is the interesting part. Testing its components separately could reveal whether changing the surrounding conditions adds something that supplementation alone cannot. Sources: Advanced Science (2026), Lifespan.io (reporting on Li et al., Advanced Science, 2026) Advanced Science (2026),: https://doi.org/10.1002/advs.77571 Lifespan.io (reporting on Li et al., Advanced Science, 2026): https://lifespan.io/blocking-sting-helps-preserve-bone-in-aging-mice/ ---