Direct Reprogramming Resets Epigenetic Age in Human Cells Over 50 Days

Study Overview

Researchers from University Hospital Bonn, University of Bonn, and RWTH Aachen University published a study in Aging Cell (October 3, 2026) investigating direct reprogramming of human blood cells into induced neural stem cells (iNSCs) and tracking epigenetic age changes.

Methodology

The study included 15 donors aged from newborn to 101 years. Peripheral blood mononuclear cells (PBMCs) were first differentiated into erythroid progenitor cells (EPCs). Using Sendai virus vectors, the transcription factors SOX2 and cMYC were transiently overexpressed to convert EPCs into proliferative neural stem cells, bypassing the induced pluripotent stem cell (iPSC) stage.

Epigenetic Age Reversal

DNA methylation age was assessed using the Horvath 2018 clock. Original EPCs showed DNA methylation age highly correlated with donor chronological age. After reprogramming, low-passage iNSCs exhibited a methylation age averaging ~13% of donor age, which further decreased to ~5% at higher passages.

Temporal Dynamics of Age Reset

Time-series analysis of three cell lines from donors aged 50–101 revealed that most age-related DNA methylation features required approximately 50 days to gradually reset. Neural lineage markers DACH1 and PAX6 were expressed by day 12, but full neural stem cell identity, as assessed by DNA methylation and RNA sequencing, continued to mature over several weeks (at least until day 26 post-conversion).

Independence from Cell Proliferation

To test whether epigenetic rejuvenation merely reflects selection of younger cells through proliferation, the researchers slowed division using glycerol and thymidine. Despite reduced population doublings, DNA methylation age continued to decline similarly to untreated controls. Additionally, differentiation toward neurons via NGN2 induction for ~20 days did not alter methylation age relative to proliferating controls, indicating that epigenetic youthening does not require ongoing cell division.

Functional Validation in Oldest Donors

Mature iNSC lines from 87- and 101-year-old donors showed no typical age-related abnormalities in nuclear lamina, autophagy, mitochondrial function, or cellular senescence markers, providing orthogonal support for the methylation clock findings.

Implications and Limitations

The model enables observation of stepwise molecular changes during reprogramming over weeks, offering a platform to test factors that accelerate or decelerate epigenetic aging. Potential applications include studying age-related neurodegenerative diseases such as Alzheimer's. However, the authors caution that DNA methylation age is a surrogate biomarker, not equivalent to overall functional cellular age. Reference data for truly aged neural stem cells are lacking, so the influence of cell identity conversion on age estimation cannot be fully excluded. The in vitro findings do not demonstrate reversal of organismal aging.

Paper link: https://onlinelibrary.wiley.com/doi/10.1111/acel.70751 ScienceDaily coverage: https://www.sciencedaily.com/releases/2026/10/261020085013.htm

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研究发现直接细胞编程伴随持续性的年龄相关分子变化。