Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression.
Level 5 - mechanism / opinion, no new human data
Preclinical animal and mechanistic study with preliminary human clinical observation
PubMed 24905167 · doi:10.1016/j.stem.2014.04.014
What was done
Researchers investigated how cycles of prolonged fasting affect long-term hematopoietic stem cells (LT-HSCs), niche cells, and immune system regeneration. The study examined circulating IGF-1 levels, PKA activity, stress resistance, self-renewal, and lineage balance in mice subjected to fasting, chemotherapy, or aging, supplemented with mechanistic manipulations of IGF-1 and PKA pathways and preliminary observations in fasting chemotherapy patients.
What was found
The abstract reports no numerical values. Prolonged fasting reduced circulating IGF-1 levels and PKA activity across various cell populations. In mice, multiple cycles of fasting lowered chemotherapy-induced immunosuppression and mortality and reversed age-dependent myeloid bias. These regenerative effects were mimicked by IGF-1 or PKA deficiency and blocked by exogenous IGF-1. Preliminary observations indicated lymphocyte protection from chemotoxicity in fasting patients.
Why it matters
The study identifies a dietary signaling axis (IGF-1/PKA downregulation via prolonged fasting) that promotes stem-cell-driven hematopoietic regeneration and protects against chemotherapy toxicity in preclinical models.
Limits
The abstract contains no quantitative data, sample sizes, or effect sizes. The primary findings are restricted to mouse models, and the human data are described only as preliminary with unspecified study design, sample size, and clinical endpoints.
Cited by
- supports In mice and humans undergoing fasting or fasting-mimicking diets, organs and white blood cell levels temporarily shrink or reduce during fasting cycles and return to normal levels upon refeeding through stem cell activation.
- supports Stem cell activation and self-renewal during fasting is low IGF-1 dependent, whereas stem cell proliferation and differentiation during refeeding are driven by high IGF-1 and insulin levels.