Old Bone Marrow Drains NAD+ From Bone-Building Cells, Preclinical Study Finds

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. 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.

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 study 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 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.

The next thing to watch is whether STING blockers, tested alone and alongside NMN, hold up in larger studies and in early human trials.

Arrowhead Reports Its Tau-Silencing Drug Lowers Spinal Fluid Tau by Up to 73% EU Drug Committee Backs Lilly's Daily Weight-Loss Pill Foundayo England's Adult Social Care Workforce Grows at Slowest Rate in Four Years BioAge and Deep Origin Launch Multi-Target AI Drug Discovery Collaboration Neko Health Brings $500 Body Scans to US With 300,000-Person Waitlist