Review: compartmentalized NAD⁺ circuits in aging, tissue repair and fibrosis
This review describes NAD⁺ as a compartmentalized, high-turnover metabolic circuit whose timing and cell-type specificity shape tissue outcomes during aging, repair and fibrosis, and proposes a framework for NAD⁺-based interventions. [1]
Automatic summary · not editorially reviewed
The key findings
The review defines NAD⁺ as a compartmentalized, high-turnover metabolic circuit whose topology, timing and cell-type specificity shape tissue trajectories during aging, repair and fibrosis. [1]
Aging reshapes these circuits through CD38 upregulation, PARP–sirtuin competition, extracellular eNAMPT amplification and altered mitochondrial NAD⁺ transport, redistributing NAD⁺ between compartments without necessarily changing bulk tissue concentration. [1]
The authors propose a framework for NAD⁺-based interventions that prioritizes timing, compartmental targeting and oncologic stratification. [1]
The source at a glance
- Study type / format
- Review (abstract only)
- Population / context
- Not specified in the abstract; the review covers heart, lung, liver, kidney, skin, muscle and brain tissue contexts.
- Summary based on
- Study abstract
- Original publication
- August 17, 2026
Review frames NAD⁺ as compartmentalized circuit
The authors define NAD⁺ not only as a redox cofactor but as a compartmentalized, high-turnover metabolic circuit. Its topology, timing and cell-type specificity are said to shape tissue trajectories during aging, repair and fibrosis. NAD⁺ fuels sirtuins, PARPs and CD38, linking metabolism to chromatin remodeling, DNA repair, calcium signaling and cell fate. A central translational question raised is whether modulating NAD⁺ in a given tissue and time window will favor regeneration, restrain fibrotic remodeling, or support malignant adaptation.
Supporting source [1]
Aging reshapes NAD⁺ pools without bulk change
The review describes how aging reshapes these circuits through CD38 upregulation, PARP–sirtuin competition, extracellular eNAMPT amplification and altered mitochondrial NAD⁺ transport. According to the authors, these processes redistribute NAD⁺ between compartments without necessarily changing bulk tissue concentration. The review also summarizes how de novo, Preiss-Handler (including niacin/GPR109a) and nicotinamide salvage pathways are organized across nuclear, cytosolic, mitochondrial and extracellular compartments, and how consumers including sirtuins, PARPs, CD38 and SARM1 govern these pools.
Supporting source [1]
Tissue contexts and proposed intervention framework
The review examines how these circuits operate across acute injury, chronic senescence-associated remodeling and malignant microenvironments in heart, lung, liver, kidney, skin, muscle and brain. It then integrates emerging human data on NAD⁺ precursors and enzyme-directed strategies. Finally, the authors propose a framework for NAD⁺-based interventions that prioritizes timing, compartmental targeting and oncologic stratification. This framework is a proposal, not a validated or approved intervention.
Supporting source [1]
How to interpret this
This is an abstract of a review; the full text was not reviewed. The abstract describes a proposed framework and emerging human data but reports no primary study design, sample size, follow-up or effect estimates. Associations and proposed mechanisms are not established causes, and the proposed framework is not a validated or approved intervention.
Based on the study abstract; the full paper, tables and supplementary data were not reviewed.
Source & supporting passages
Izadpanah R, Rappaport J, Alt EU. · europepmc.org · August 17, 2026