Label-Free Raman Imaging Joins Transcriptomics to Map Senescence in Aging Tissue

Cellular senescence, the state in which damaged or stressed cells permanently exit the cell cycle yet remain metabolically active, has become one of the most intensively studied phenomena in modern biology. These cells accumulate in tissues as organisms age, and they also appear transiently at sites of injury, where they participate in wound repair before being cleared by the immune system. The trouble for researchers has always been detection. Senescent cells are notoriously heterogeneous, and the markers used to identify them, such as the cell-cycle inhibitor p21, the enzyme SA-beta-galactosidase, or telomere-associated DNA damage foci, are individually imperfect and often require labeling, staining, or genetic engineering that can perturb the very biology being studied. A new study published in Nature Aging by Zhang, Chen, Monticolo, Sorrentino and colleagues describes a strategy that promises to change how senescence is observed: a framework the authors call RamanOmics, which pairs label-free Raman imaging with spatial and single-cell transcriptomics to decode the molecular architecture of senescence in aging and repair.

Raman spectroscopy is built on a simple physical principle with powerful biological consequences. When laser light scatters off molecules, a small fraction of the photons exchanges tiny amounts of energy with molecular vibrations, and the resulting spectral shifts form a fingerprint of the chemical bonds present in the sample. Lipids, proteins, nucleic acids and carbohydrates all produce distinctive vibrational signatures, which means a Raman spectrum acquired from a living cell is, in effect, a quantitative chemical readout of its internal composition. Crucially, the method requires no dyes, no antibodies and no genetic modification, eliminating many of the artifacts and biases that complicate fluorescence-based approaches. The authors of the new work recognized that this chemical richness, combined with spatial resolution at the level of individual cells and subcellular compartments, could offer a window into senescence that no single molecular marker could provide.

The central innovation of RamanOmics lies in integration. Rather than using Raman imaging as a stand-alone imaging modality, the researchers systematically aligned vibrational spectra with gene-expression data obtained from matched tissue regions and single cells. Spatial transcriptomics maps messenger RNA abundances across intact tissue sections, preserving the geographic relationships between cells, while single-cell transcriptomics resolves expression states cell by cell. By overlaying these maps with label-free Raman images of adjacent or identical tissue sections, the team could ask a question that neither technology answers alone: which biochemical vibrational signatures correspond to which transcriptional states in the intact spatial context of aging or regenerating tissue?

The most striking finding to emerge from this analysis is a lipid-linked Raman signature associated with p21-positive cells. Cells expressing high levels of p21, a canonical enforcer of the senescence cell-cycle arrest, displayed a distinctive vibrational profile dominated by lipid features, suggesting that these cells undergo reproducible changes in their lipid composition or lipid storage as they enter senescence. This is consistent with a growing body of evidence that senescent cells accumulate neutral lipids and alter membrane composition, but the new work goes further by demonstrating that this lipid remodeling is spatially organized and detectable without any label. In principle, this means researchers could identify senescent cells in intact, unstained tissue by their chemical fingerprints alone, opening the door to quantitative mapping of senescence burden across organs, across ages, and across disease states.

Why would senescent cells show altered lipid signatures? Senescence is a metabolically demanding state. Cells in senescence secrete inflammatory cytokines, growth factors and matrix-remodeling enzymes, collectively known as the senescence-associated secretory phenotype, and they sustain this activity while remaining growth-arrested. Lipid droplets and membrane lipids are deeply involved in these processes, serving as energy reserves, signaling platforms and sources of secreted lipid mediators. A vibrational signature concentrated in lipid bands therefore plausibly reflects the reorganization of lipid metabolism that accompanies the senescence program. The alignment of this signature with p21 expression through transcriptomic overlay gives the spectral observation a molecular anchor, transforming what could be an ambiguous spectroscopic pattern into a biologically interpretable feature.

The relevance of the method extends beyond basic cell biology because senescence is double-edged. In aging tissues, the accumulation of senescent cells contributes to chronic inflammation, tissue dysfunction and a host of age-related pathologies, and pharmaceutical approaches called senolytics aim to remove these cells to extend healthspan. Yet in wound repair, senescent cells appear transiently and appear to be beneficial, promoting tissue regeneration, recruiting immune cells and stimulating progenitor activity before being eliminated. A tool that can distinguish and map senescence in both contexts, without labels that might bias the analysis, is therefore valuable for understanding when senescence is a driver of decline and when it is a constructive part of healing. The spatial dimension is essential here: the same cell type may be harmful in one tissue microenvironment and helpful in another, and only spatially resolved methods can capture that distinction.

The technical achievement of RamanOmics also highlights a broader trend in the life sciences, the convergence of physics-based imaging with computational genomics. Raman spectra are high-dimensional data, and extracting biological meaning from them requires machine learning and careful calibration against independent measurements. By treating spectra as molecular phenotypes and training the analysis on transcriptomic ground truth, the researchers effectively created a dictionary that translates vibrational features into biological states. This translational framework is what gives the approach its name and its potential generality. If the dictionary can be extended to other cell states, cell types and tissues, Raman imaging could evolve from a specialized physical technique into a routine omics platform, one that measures chemistry directly in intact tissue rather than inferring it from dissociated cells.

There are, of course, important questions ahead. Raman signals are inherently weaker than fluorescence, so imaging speed and sensitivity remain practical constraints, particularly for three-dimensional or large-field applications. Spectral assignments can be ambiguous, and the correspondence between vibrational features and specific lipid species or metabolic states will require continued validation against orthogonal chemical methods. Translating findings from experimental models of aging and repair to human tissue will demand demonstration that the lipid-linked signature of p21-positive cells is conserved across species and disease contexts. Nonetheless, the conceptual advance is clear. The study establishes that label-free vibrational imaging can carry biologically meaningful, transcriptomically anchored information about a complex and clinically significant cell state, and that this information can be placed precisely within tissue architecture.

The implications ripple outward to drug development and diagnostics. Senolytic and senomorphic therapies currently lack robust pharmacodynamic biomarkers, and clinical trials would benefit enormously from a way to measure senescent cell burden in tissue biopsies without relying on a patchwork of imperfect stains. A validated Raman-based readout of senescence could serve exactly this role, providing quantitative, spatially resolved, label-free assessment of whether an intervention is actually reducing the senescent population in a target tissue. Similarly, in regenerative medicine, where controlled induction of transient senescence may be a feature of successful healing, the technology could monitor whether engineered tissues or cell therapies recapitulate the beneficial phase of the senescence program without tipping into chronic, pathological accumulation.

What makes this work resonate beyond its immediate findings is the way it reframes an old biological question with new instrumentation. Senescence has been studied for decades through lens-based microscopy and molecular assays, each revealing a fragment of the phenomenon. RamanOmics stitches those fragments together by reading the chemistry of cells directly and aligning it with the genetic programs they express, all in the spatial context of aging and repair. If the framework proves broadly applicable, the vibrational landscape of tissue may become as routinely interrogated as its transcriptome, and the enigmatic cells that linger at the crossroads of aging and healing will finally be seen in full chemical detail, without ever having to touch them with a label.

Subject of Research: Label-free Raman imaging integrated with spatial and single-cell transcriptomics to identify molecular signatures of cellular senescence in aging and tissue repair.

Article Title: RamanOmics decodes the spatial vibrational–molecular architecture of senescence in aging and repair

Article References: Zhang, K., Chen, X., Monticolo, F., Sorrentino, S., Huang, H., Callahan, C., Qiao, Y., Zhou, J., Brodowska, S., Sapantzi, S., Qi, J., Wu, Y., Dang, T. N. S., Cao, Y., Kang, S., Viggiani, F., Ho, C.-K., Xu, Y., Kobayashi-Kirschvink, K. J., … Shu, J. (2026). RamanOmics decodes the spatial vibrational–molecular architecture of senescence in aging and repair. Nature Aging. https://doi.org/10.1038/s43587-026-01219-7

Image Credits: AI Generated

DOI: 10.1038/s43587-026-01219-7

Keywords: RamanOmics, cellular senescence, Raman spectroscopy, spatial transcriptomics, single-cell transcriptomics, p21, lipid signature, aging, tissue repair, senolytics, label-free imaging, Nature Aging