September 17, 2026

What Happens to Skin Cell Signaling as We Age?

Skin cells don't work in isolation; they're constantly sending and receiving chemical instructions. Learn what cell signaling actually does in skin, how it's discussed as changing with age, and why some of that change...

What to know

Skin cells coordinate repair, growth, and renewal through chemical signals, including growth factors, that travel between cells.
Research describes several separate processes associated with age-related changes in this signaling, including shifts in growth factor activity, the emergence of senescent cells, and a broader pattern known as inflammaging.
NAD+, a molecule involved in cellular energy, is also discussed in the research as relevant to how well cells communicate internally, as it declines with age.
These are areas of ongoing scientific study, not fully settled mechanisms, and none of them are reversed by a topical product alone.

Skin cells aren't working alone. At any given moment, keratinocytes, fibroblasts, and immune cells are exchanging chemical messages, instructions to divide, repair, produce collagen, or stand down. This constant back-and-forth is called cell signaling, and it's one of the quieter processes behind how skin looks and behaves. Research describes this signaling as changing with age, not simply slowing down, but in some cases shifting toward a different kind of message entirely.

What Cell Signaling Actually Does in Skin

Growth factors are one of the main messengers in this system, proteins that bind to receptors on a cell's surface and prompt a specific response inside it. In skin, growth factors are associated with coordinating fibroblast activity, the cells involved in producing collagen and elastin, as well as keratinocyte behavior in the outer layer.¹

When this signaling is functioning as described in the research, it's discussed as part of what supports skin's ability to renew itself, repair UV-related damage, and rebuild structural proteins over time.

How Signaling Changes With Age

Several processes are described in the research as contributing to how cell signaling shifts with age, ranging from changes in how strongly cells respond to growth factors to the emergence of cells that send an entirely different kind of signal. These processes are generally studied separately, though they're often discussed together as part of the same broader picture of aging skin.

Changes in Growth Factor Signaling

Growth factors are associated with coordinating fibroblast activity in skin, including processes tied to collagen and elastin production.¹ Research on skin and connective tissue cells describes changes in this signaling activity as one of several factors discussed in relation to age-related shifts in fibroblast behavior, though the available research describes associations between growth factor signaling and cell function rather than establishing a single, confirmed cause of age-related change. This is an area of ongoing study rather than a fully settled mechanism.

Senescent Cells Send a Different Signal

Some cells respond to age-related stress by stopping division altogether, without dying. The National Institute on Aging describes these senescent cells as taking on a distinct identity called the senescence-associated secretory phenotype, or SASP, in which the cell remains metabolically active and secretes its own mix of growth factors, cytokines, and matrix-degrading enzymes.²

Rather than falling silent, a senescent cell is described as continuing to signal, with research associating this altered signaling with effects on nearby cells and tissue over time. NIA-supported research has traced part of this activity to a specific pathway, in which a protein called TXNRD1 is associated with driving SASP activity through an immune signaling route known as cGAS-STING.³

Inflammaging: A Broader Pattern of Chronic Signals

Alongside these cell-level changes, aging is associated with a broader shift in the body's baseline immune signaling. The National Institute on Aging describes this pattern as inflammaging, a chronic, low-grade, sterile inflammation reported in most older individuals and marked by persistently elevated pro-inflammatory cytokines.⁴

NIA-supported research has associated part of this pattern with reduced mitochondrial calcium uptake in immune cells, a mechanism researchers describe as amplifying inflammatory signaling in aged tissue.⁴ In skin specifically, this kind of background inflammatory signaling is discussed as one additional layer that cells are managing alongside repair and growth signals, rather than a separate, unrelated process.

NAD+ and Cellular Communication

Signaling requires energy, and much of that energy runs through NAD+, a molecule involved in cellular metabolism broadly. NIA-supported research describes NAD+ availability as decreasing with age, which is associated with reduced activity of sirtuins, a family of proteins that depend on NAD+ and are discussed in relation to communication between a cell's nucleus and its mitochondria.⁵

One study on skin fibroblasts specifically found that restoring NAD+ levels was associated with changes in collagen-related gene expression that persisted for more than ten days after treatment ended, a finding the study's authors describe as consistent with NAD+ playing a role in fibroblast gene expression beyond simply providing cellular energy.⁶ This reflects the findings of a single study and is discussed here as an area of active research rather than an established mechanism.

What This Means for a Daily Routine

None of these signaling changes, growth factor shifts, SASP activity, inflammaging, or declining NAD+ are things a topical product can reverse outright, and it's worth being skeptical of any claim that suggests otherwise. What a daily routine can realistically offer is consistent, low-friction support alongside these processes over time, which is part of why habit and consistency are often discussed as mattering as much as any single ingredient.

A combined serum and moisturizer used at the same time every day is one way to keep that habit simple enough to maintain. Darkfin Labs' Longevity Protocol is one example of a product formulated with ingredients associated with this same signaling category, combining a growth factor peptide complex with an NAD+ precursor in a single daily step.

Final Words

Skin cells spend much of their time listening as well as acting, responding to growth factor signals, immune signals, and energy cues tied to NAD+-dependent pathways. Research describes several distinct changes to this signaling environment with age: growth factor activity shifts, senescent cells begin sending a different kind of signal, background inflammatory signaling rises, and the cellular energy needed to support communication becomes less available.

These are active areas of scientific study rather than fully resolved mechanisms, and understanding them as ongoing research is a more accurate way to think about what's currently known about aging skin.