The term peptides is widely used in aesthetic medicine and cosmeceuticals, yet it is often misunderstood or oversimplified. From a biological standpoint, peptides are short chains of amino acids. Their presence alone does not automatically imply regenerative activity. For a molecule to induce true skin bioregeneration, it must reach viable target cells within the skin and trigger measurable biological responses.

• The main limitation is the skin barrier.

The stratum corneum is highly selective. In practical terms, molecules larger than approximately 500 Daltons do not penetrate intact skin in biologically meaningful amounts. Most peptides marketed for aesthetic purposes exceed this threshold.

As a result, the vast majority of topical peptides:

• remain on the skin surface,

• act as film-forming or moisturizing agents,

• or provide a cosmetic sensory effect rather than a true biological one.

In theory, very low–molecular-weight peptides (dipeptides or tripeptides) may serve as cellular bionutrients if—and only if—they:

• are sufficiently small,

• remain stable,

• reach viable skin cells,

• and are present at effective intracellular concentrations.

In standard topical formulations, these conditions are rarely met simultaneously.

• Some peptides demonstrate biological activity in vitro, under controlled laboratory conditions and at concentrations that do not reflect real-world topical application.

However, in vitro activity does not equate to in vivo clinical efficacy.
Without proven penetration, cellular uptake, and reproducible clinical outcomes, these findings remain experimental rather than therapeutic.

True bioregeneration involves measurable biological processes, such as:

• fibroblast activation,

• extracellular matrix synthesis,

• controlled inflammatory modulation,

• tissue remodeling within the viable dermis.

These processes require real biological stimulation, not surface signaling alone.

Exosomes are extracellular vesicles involved in intercellular communication in living systems. In their native biological context, they are produced by viable cells and function within highly controlled microenvironments.

In aesthetic medicine, however, the majority of so-called “exosome-based” topical products face fundamental limitations:

• lack of cellular origin traceability,

• absence of viability after processing and storage,

• inability to penetrate intact skin barriers in functional form.

Moreover, exosomes require cellular uptake within viable tissue to exert biological effects. When applied topically, they do not reliably reach target cells in the dermis, nor do they demonstrate reproducible in-vivo regenerative outcomes.

Conclusion:
Topical exosomes may contribute to surface conditioning, but they do not replace real metabolic or cellular stimulation within living skin tissue.

Plant stem cells and human stem cells are biologically and genetically distinct. While plant-derived extracts may contain antioxidant or protective compounds, they do not function as stem cells in human tissue.

Plant stem cells:

• cannot differentiate into human skin cells,

• do not integrate into human cellular signaling pathways,

• do not activate dermal regeneration mechanisms.

Their use in aesthetic products is therefore conceptual rather than biological, relying on symbolic terminology rather than functional equivalence.

Conclusion:
Plant stem cells do not induce skin regeneration and should not be confused with human cellular therapies.

No. Retinol and retinoic acid are pharmacologically distinct molecules.

Retinol is a precursor that must undergo multiple enzymatic conversions within the skin to become biologically active retinoic acid. This conversion:

• is variable between individuals,

• decreases with age,

• is significantly influenced by skin condition and metabolism.

As a result, retinol provides indirect and inconsistent biological stimulation, whereas retinoic acid exerts direct, receptor-mediated activity.

Conclusion:
Retinol is a cosmetic modulation tool, not a therapeutic equivalent of retinoic acid, and its regenerative potential remains limited and unpredictable.

Growth factors are large, complex proteins designed to act within tightly regulated biological systems. For activity, they must:

• reach viable target cells,

• bind to specific receptors,

• maintain structural integrity.

When applied topically, most growth factors:

• exceed the molecular size required for skin penetration,

• are rapidly degraded,

• fail to reach dermal targets in effective concentrations.

While in vitro studies may demonstrate cellular responses, clinical in-vivo evidence of true dermal regeneration via topical growth factors remains insufficient.

Conclusion:
Topical growth factors do not substitute for genuine biological stimulation of living tissue.

A metabolic peel is defined by its ability to activate biological processes within viable skin tissue, rather than merely removing the stratum corneum.

Unlike purely exfoliative or keratolytic peels, metabolic peels:

• interact with skin metabolism,

• induce adaptive cellular responses,

• stimulate controlled remodeling processes over time.

Their efficacy is not measured by visible frosting or acute desquamation, but by progressive, reproducible tissue response.

Conventional chemical peels primarily act through surface injury and exfoliation. Their effect is immediate and visible but often short-lived.

Metabolic peels, in contrast:

• modulate skin physiology rather than injuring it,

• act through biochemical signaling and pH-dependent mechanisms,

• aim for long-term tissue adaptation instead of acute damage.

This distinction explains their superior safety profile and their suitability for repeated treatments.

Visible peeling reflects keratinocyte shedding, not dermal regeneration.

True biological efficacy occurs below the surface and may not be immediately visible. Excessive desquamation often indicates overtreatment rather than optimal stimulation.

In metabolic peeling, absence of visible peeling does not equal absence of effect.

pH determines the biological behavior of active acids.

Small pH variations influence:

• acid ionization,

• penetration depth,

• enzymatic activation,

• inflammatory response.

Metabolic peels are designed to operate within biologically controlled pH ranges, ensuring stimulation without tissue injury.

Because they stimulate rather than damage tissue, metabolic peels:

• can be safely repeated,

• allow cumulative biological benefits,

• reduce the risk of post-inflammatory complications.

Long-term protocols aim to slow functional skin aging rather than produce isolated cosmetic effects.

Yes. Metabolic peels integrate well with:

• injectables,

• energy-based devices,

• topical maintenance therapies.

Their role is to optimize tissue quality, improving response to other aesthetic interventions.

Efficacy should be assessed through:

• tissue texture and density,

• skin tone homogeneity,

• elasticity and functional resilience,

• long-term stability of results.

Short-term erythema or exfoliation is not a reliable endpoint.

Short answer: Yes. Peel Deluxe Plus can be safely combined with TCA Cream, especially in the treatment of ice-pick and atrophic acne scars. Its main role in this context is not to increase the peeling depth, but to act as a frosting stopper.

Clinical use

When an acid peel such as TCA begins to show a grey frosting that is about to turn white, the immediate application of Peel Deluxe Plus helps stop the progression of the frosting. This allows the physician to control the exact depth of the peel and to avoid unnecessary tissue damage.

Perilesional protection

Peel Deluxe Plus is also very useful when applied perilesionally. It helps prevent an intense white frosting from spreading beyond the intended treatment area and protects the surrounding skin.

Metabolic effect

In addition to stopping the frosting, Peel Deluxe Plus has a metabolic action. It stimulates basal keratinocytes, which then migrate toward the surface and replace damaged cells. This replacement mechanism is typical of metabolic peelings and clearly differs from the classic “burn and repair” concept of traditional acid peels.

Short answer: As a general rule, topical retinoids should be stopped 7 days before and 7 days after a metabolic peel.

Clinical recommendation

• Standard skin: stop topical retinoids 7 days before the peel and restart 7 days after, if the skin barrier is intact.
• Very sensitive or reactive skin: the retinoid-free interval can be extended to 10 days before and after the procedure.

The exact timing can be adapted according to the patient’s skin condition and the physician’s clinical judgment. The goal is to avoid cumulative irritation and to keep the epidermal barrier stable around the time of the peel.

Short answer: Alpha-lipoic acid is used primarily as a penetration enhancer. Its main role is to help other active ingredients penetrate deeper and more evenly into the skin.

Clinical role

Alpha-lipoic acid is not just another active ingredient. It is designed to carry other molecules through the epidermis and into deeper layers. This makes it particularly useful in:

• Dehydrated skin: mix alpha-lipoic acid with a fast-penetrating moisturizing cream (for example, Les Félins) to improve deep hydration.
• Non-superficial hyperpigmentation: combine alpha-lipoic acid with depigmenting formulations such as Stretchpeel (kojic acid based) to enhance their penetration and efficacy.

Post-peel protocol

• Use once daily at night for 7–10 days after the peel.
• Then continue 2–3 times per week as maintenance, or mix with other topical products depending on the indication.

The key message is that alpha-lipoic acid is mainly a vehicle and amplifier for other actives, especially in metabolic peeling protocols.

Short answer: Post Peel Cream is particularly useful for patients who cannot come for regular follow-up visits or repeated sessions. It helps soften and secure a strict protocol when close supervision is not possible.

Main indications

• Limited follow-up: patients living far away or unable to attend frequent controls.
• Reactive skin: patients with a history of irritation or barrier fragility.

How to use it

• As a stand-alone post-peel cream for the first days after treatment in sensitive patients.
• In combination with alpha-lipoic acid, for example:
  • Morning: Post Peel Cream (for comfort, hydration and barrier support).
  • Evening: alpha-lipoic acid, once the skin tolerates it, to enhance penetration of other actives.

In very reactive skin, Post Peel Cream can be used alone during the first 48 hours, then alpha-lipoic acid is reintroduced gradually once the epidermal barrier is more stable.

Short answer: Yes. Gradient Cream is well suited as a daytime moisturizer, especially for mature skin.

Clinical benefits

• Improves overall skin texture.
• Enhances surface uniformity and tone.
• Supports the hydrolipidic film and barrier function.

How to integrate it

In many patients, Gradient Cream can replace a conventional day cream and become the main daytime treatment. A typical layering would be:

• Morning: gentle cleansing, vitamin C serum, Gradient Cream, then an appropriate sunscreen (for example, Stretchpeel).

It is particularly interesting in combined protocols for photo-aging, fine lines and texture irregularities.

Short answer: In most cases, yes. Papaya Cream is usually a safer and more intelligent alternative to glycolic acid–based night creams.

Why we avoid free glycolic acid

From a biochemical perspective, glycolic acid is monoprotic and has a less favorable pKa profile compared with triprotic citric acid. Clinically, this often means:

• more irritation,
• less predictability,
• higher risk for barrier damage and post-inflammatory hyperpigmentation.

Advantages of Papaya Cream

• Belongs to the family of fruit acids / AHAs, but acts mainly through enzymatic exfoliation.
• Provides gentle, regular exfoliation with far fewer side effects.
• Better tolerated on long-term use, even in sensitive or mixed skin types.

For these reasons, Papaya Cream can advantageously replace glycolic acid products (such as Dermasence) in patients who need controlled exfoliation without the typical drawbacks of free glycolic acid.

Short answer: We prefer simple, transparent routines without hidden irritants. We generally avoid classic toners/tonics and alcohol-based sunscreens, and we focus on alcohol-free photoprotection and clearly formulated products.

Morning routine

• Cleansing: gentle cleanse with Aseptiderm.
• Antioxidant: vitamin C serum.
• Moisturizer: Gradient Cream as a daytime moisturizer, especially for mature skin.
• Photoprotection: Stretchpeel as an alcohol-free sunscreen (real-life protection in the SPF 50–60 range).

Evening routine

• Cleansing again with Aseptiderm.
• Exfoliation: Papaya Cream for mild enzymatic exfoliation.
• Penetration enhancement: alpha-lipoic acid, applied alone or mixed with a suitable cream, according to the skin’s needs.

What we recommend avoiding

• Toners/tonics with hidden irritant, comedogenic or alcoholic ingredients.
• Conventional sunscreens that rely heavily on alcohol as a solvent, as they may impair the barrier and contribute to pigment disorders.

Short answer: In standard practice, we recommend an interval of at least 15 days before and 15 days after between a fractional laser session and a metabolic peel.

Standard setting

• Before laser: wait at least 15 days after a peel.
• After laser: wait at least 15 days before performing a new peel.

This interval allows sufficient epidermal repair and helps reduce the risk of excessive inflammation or post-inflammatory hyperpigmentation.

Advanced combination protocols (experienced physicians only)

In experienced hands, more aggressive combination protocols can be performed in the same session, for example:

• Er:YAG or CO₂ fractional laser,
• TCA (photodetersion),
• Peel de Luxe,
• Stretchpeel,
• alpha-lipoic acid.

During desquamation, the laser spots detach in thin plates, similar to the skin of sushi, which is why we refer to this as the “Sushi Peel”. Typically, 2 sessions, maximum 3, are sufficient to avoid post-inflammatory hyperpigmentation while achieving excellent clinical results, including in Asian skin types.

Short answer: The occurrence of inflammatory breakouts with Les Félins is not expected and should always trigger a quality-control check.

Immediate steps

• Ask the patient to stop the product temporarily.
• Document the reaction with clinical photos, timing and a list of all concomitant products.
• Record and communicate the batch (lot) number of the product.

Quality-control procedure

The batch number allows us to contact other customers who received the same lot and to check whether similar reactions have been reported. This helps us rule out contamination, formulation deviation or inappropriate combinations with other products.

This systematic approach is part of our safety and traceability standards, and it helps maintain consistent product quality for all patients.