Cell reprogramming for aging and disease: animal evidence and early human testing
A 2026 review compares three ways to rewrite cell identity, from rejuvenating aged tissue to fighting cancer, and asks where each is safe enough for humans.
Summary
Cell reprogramming forces cells to change their identity, and this review sorts the field into three approaches. Direct reprogramming converts one mature cell type into another, such as skin cells into neurons. Partial reprogramming briefly switches on youth-restoring factors to reverse aging features without erasing cell identity. Cell fusion merges two cells and can either fuel cancer or power vaccines. In mice, partial reprogramming has extended lifespan and improved tissue repair, and a therapy called ER-100 is the first of its kind cleared by the FDA to start human testing. The authors stress that most evidence is still preclinical. Low efficiency, delivery problems, and long-term tumor risk remain unsolved, and benefits do not prove a cell's identity has changed completely, stably, or safely.
Detailed Summary
Cell reprogramming forcibly alters a cell's epigenetic state and gene-expression network. This 2026 review in Research organizes the field by therapeutic application, including cancer, neurodegeneration, aging, and regenerative medicine. It compares direct reprogramming, partial reprogramming, and cell fusion-induced reprogramming, and proposes an operational framework for defining a safe therapeutic window.
The authors describe several foundational experiments. Davis showed in 1987 that MYOD1 could convert fibroblasts into stable myoblasts. In 2006, Takahashi and Yamanaka showed that OCT4, SOX2, KLF4, and c-MYC (OSKM) could reprogram somatic cells into a pluripotent state. The review credits Ocampo and colleagues with demonstrating that short-term, cyclic OSKM expression in mice could reverse aging-associated phenotypes and extend lifespan without inducing full pluripotency. The supplied passage does not specify the mouse model for that particular experiment.
Direct reprogramming converts cells across mature lineages without an intermediate pluripotent state, generally using transcription factors or small molecules. Table 1 lists 27 representative strategies. Examples include fibroblasts to functional neurons using BRN2, ASCL1, and MYT1L; fibroblasts to dopaminergic neurons using ASCL1, NR4A2, and LMX1A; and astrocytes to neurons using NEUROD1 delivered by AAV. Other examples generate cardiomyocyte-like cells, hepatocytes, chondrocytes, and photoreceptor-like cells. In oncology, the table includes cancer-cell conversions into macrophages, cDC1 dendritic cells, adipocytes, and hepatocytes. The abstract reports that converting cancer cells into antigen-presenting cells can elicit durable antitumor immunity and remodel the tumor microenvironment.
Partial reprogramming aims for functional renewal through limited epigenetic remodeling while preserving cell identity. The review reports lifespan extension, reduced multiorgan pathology, and improved regenerative capacity in mouse models of progeria and natural aging, while stressing that the strength and reproducibility of findings vary across models. ER-100 is described as the first regenerative therapy based on partial epigenetic reprogramming to receive FDA Investigational New Drug approval and enter clinical testing. The supplied text reports no human safety or efficacy results for ER-100.
Cell fusion has both pathological and therapeutic roles. Fusion between tumor cells and mesenchymal stem cells or immune cells can cause genomic mixing and chromosomal instability, contributing to malignant heterogeneity, metastasis, and drug resistance. Conversely, dendritic cell–tumor fusion vaccines and hybrid-derived exosome strategies have shown potential to activate antitumor immunity in animal models and early clinical studies. The review defines fusion-induced reprogramming as fusion that produces stable reconstruction of cell state; not every fusion event does so.
The authors emphasize that therapeutic benefit does not establish complete, stable, or safe cell-fate conversion. Major translational barriers include low reprogramming efficiency, insufficient delivery, poor targeting, an incompletely defined safety window, and long-term tumorigenic risk. Selecting in vivo or ex vivo approaches requires attention to disease context. Single-cell multiomics, artificial intelligence, nonviral delivery, and tissue engineering are presented as possible routes to improving translation, rather than established solutions.
Key Findings
- Three reprogramming modalities are compared: direct (lateral lineage conversion), partial (limited epigenetic reset without pluripotency), and cell fusion-induced (stable state reconstruction after cell merging)
- In progeria and naturally aged mice, partial reprogramming extended lifespan, ameliorated multiorgan pathology, and improved tissue regeneration, though strength and reproducibility vary across models
- ER-100 is the first regenerative therapy based on partial epigenetic reprogramming to receive FDA Investigational New Drug approval and enter clinical testing
- Direct reprogramming has converted fibroblasts or astrocytes into functional dopaminergic and cortical neurons in vitro and in vivo, using factor sets such as ASCL1/NR4A2/LMX1A or NEUROD1 via AAV
- Reprogramming cancer cells into antigen-presenting cells (e.g., cDC1 via PU.1/IRF8/BATF3) elicited durable antitumor immunity and remodeled the tumor microenvironment in preclinical work
- Cell fusion can contribute to malignant progression, but dendritic cell–tumor fusion vaccines and hybrid-derived exosome strategies have shown potential to activate antitumor immunity in preclinical models and early clinical studies
- Low reprogramming efficiency, delivery and targeting problems, an incompletely defined safety window, and long-term tumorigenic risk remain major barriers; therapeutic benefits do not establish stable or safe cell-fate conversion
Methodology
This is a review organized around therapeutic applications rather than a report of a new experiment. It compares three reprogramming strategies across cell-identity reconstruction, epigenetic barriers, intermediate-state stability, delivery efficiency, and safety. The supplied material includes the abstract, introduction, direct-reprogramming section, and Table 1, ending during the table's abbreviation list. No search strategy, pooled statistics, or formal evidence grading is shown in this excerpt, so the full review methodology cannot be assessed. The authors characterize the evidence as predominantly preclinical.
Study Limitations
The authors note that most evidence is preclinical, that the strength and reproducibility of findings vary across experimental models, and that reported benefits do not establish complete, stable, or safe cell-fate conversion. Low reprogramming efficiency, insufficient delivery, poor targeting, an incompletely defined safety window, and long-term tumorigenic risk remain unresolved. The supplied excerpt does not provide human safety or efficacy results for ER-100 or conflict-of-interest information.
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