Table 1.
Measurable aging biomarkers for mice and humans1
| Biomarker | Strengths | Weaknesses |
|---|---|---|
| Senescence Associated β-galactosidase stain | - Highly validated in vitro | - Non-quantitative - Correlation with chronologic aging is undefined - High background in certain tissues in vivo - No causal role in aging |
| Leukocyte Telomere Length | - Can be assessed on peripheral blood - Supported by GWAS, murine studies as having causal role in some aspects of aging biology |
- Inter-individual heterogeneity is high - Correlation with chronologic aging is low (R2 <0.2) - High quality assays are complex and costly - Small dynamic range (~30% change) |
| Il-6, other SA-cytokines | - Easy to measure in serum from peripheral blood | - Inter-individual heterogeneity is high - Correlation with chronologic aging is low (R2 <0.1) - Affected by minor inter-current illness - Causal role in aging unclear |
| p16iNK4a mRNA in T-lymphocytes | - Validated in vitro and in murine models - Highly dynamic (>10-fold change) - Chronologic aging R2 is high (>0.5) - Supported by GWAS, murine studies as having causal role in some aspects of aging biology |
- Requires sorted T cells - RNA marker |
| DNA Methylation | - Easy to quantitate - Can be assessed on DNA from peripheral blood - Chronologic aging R2 is very high (0.5 to 0.9) |
- Role in aging is unclear - Array cost is expensive, but may be possible to do in cheaper PCR format |
1
Abbreviations: GWAS, Genome wide association study; Il-6, Interleukin-6; SA, senescence associated.