l-Carnitine regulates regeneration of human hematopoietic stem and progenitor cells.

Understanding how metabolism governs human hematopoietic stem cells (HSCs) function is essential for advancing regenerative therapies, yet direct metabolic profiling of human HSCs has been limited by their extreme scarcity and the technical limitations of conventional methods. Here, we applied a low-input mass spectrometry-based metabolomics platform, optimized for rare cell populations, to generate metabolic profiles of 13 immunophenotypically defined hematopoietic cell types from adult human bone marrow. Using as few as ∼10 000 cells per sample, we detected >80 metabolites and uncovered both conserved metabolic programs in primitive hematopoietic stem and progenitor cells (HSPCs) and lineage-specific metabolic specializations. Of note, we identified l-carnitine-driven fatty acid oxidation as a key metabolic feature supporting HSPC function. Mechanistically, l-carnitine activates the peroxisome proliferator-activated receptor alpha-transcription factor EB signaling axis, promoting mitochondrial metabolism and autophagy to preserve regenerative capacity. Functional assays in primary CD34+ HSPCs derived from healthy donors or patients with aplastic anemia confirm that l-carnitine supplementation improves stem cell function ex vivo and in vivo. This work provides a foundation for human hematopoietic metabolism and reveals a targetable metabolic circuit governing HSPC regenerative fitness with therapeutic potential for improving stem cell-based interventions.