Signal peptides in modern cosmetology: addressing keyconcerns of ageing skin

Today’s aesthetic-medicine patient rarely asks simply to “rejuvenate” the skin. More often, the request sounds like this: “My skin feels less firm”, “I’ve noticed my first fine lines”, “My face looks tired”, or “My usual cream no longer gives the same result”. Behind these concerns lies a set of physiological changes that occur in the skin with age and under the influence of external factors.

The peptide line based on Acetyl Tetrapeptide-9 and Acetyl Tetrapeptide-11 was developed

specifically to address these mechanisms. It does more than hydrate the skin: it targets the causes of declining skin quality, including slower collagen synthesis, a weakened barrier function and impaired regeneration.

The patient’s main request

“I want my skin to look firmer, smoother and fresher. I am concerned about my first fine lines, loss of firmness, and the fact that my skin no longer responds as well to my usual skincare.”

This request commonly arises after the age of 30, when catabolic processes begin to dominate in the skin: collagen synthesis slows down while its breakdown accelerates. Patients notice that familiar moisturising products no longer deliver sufficient results, because the issue is not only a lack of moisture but also a change in skin structure.

Which concerns the peptides address

1. Loss of density and firmness

With age, dermal fibroblasts produce less type I collagen — the main structural protein responsible for the skin’s mechanical strength. Lumican levels also decline; this protein helps organise collagen fibrils. As a result, the skin becomes less dense, and sagging and fine lines may appear.

Solution: Acetyl Tetrapeptide-9 supports the synthesis of type I collagen and lumican, helping to maintain the dermal matrix and the skin’s mechanical properties.

2. Slower cell renewal

With age, epidermal renewal slows down: keratinocytes divide more slowly, the stratum corneum becomes less even, and the skin loses radiance and smoothness. Patients often describe this as dullness, an uneven tone, or skin that “looks grey”.

Solution: Acetyl Tetrapeptide-11 supports keratinocyte proliferation, promoting natural epidermal renewal and improving skin texture.

3. Weakened barrier function

A compromised barrier leads to increased transepidermal water loss, tightness, flaking and

heightened sensitivity. Even with moisturising products, the skin may struggle to retain water.

Solution: Acetyl Tetrapeptide-11 supports syndecan-1 synthesis, which is involved in cell adhesion and extracellular-matrix organisation, helping to reinforce the skin barrier.

4. Weakening of the dermal-epidermal junction

With age, the junction between the epidermis and dermis becomes less stable. This affects the skin’s mechanical resilience and its ability to regenerate, contributing to wrinkle formation and loss of firmness.

Solution: Acetyl Tetrapeptide-11 supports the synthesis of collagen XVII, a key component of

hemidesmosomes that anchors the epidermis to the dermis.

Clinically relevant results

Patient concern	Mechanism of action	Result
Loss of firmness	Stimulation of type I collagen and lumican synthesis Improved skin density and firmness
Dullness and uneven texture	Support of keratinocyte renewal	Smoother, more radiant skin
Dehydration and tightness	Reinforcement of the barrier function	Improved moisture retention
Fine lines and wrinkles	Support of the dermal matrix and dermal-epidermal junction Reduced visibility of wrinkles

In clinical studies, the combination of Acetyl Tetrapeptide-9 and Acetyl Tetrapeptide-11

demonstrated an increase in dermal density after 28 days of use, while after 56 days it showed a statistically significant reduction in wrinkles and improvement in skin elasticity.

Why this matters for the patient

The peptide line addresses the key request of the modern patient: not simply to “hydrate”, but to

restore skin quality. It is suitable for those who want to:

• maintain firmness and density;

• reduce the visibility of early fine lines;

• restore radiance and an even skin texture;

• strengthen the skin barrier;

• choose a science-based anti-ageing approach without aggressive intervention.

Next-generation signalling peptides are a tool that enables practitioners to