Creative Touch Permanent Makeup and Aesthetics

The key distinction for epidermal treatments is between those that act at the epidermis – working on the keratinocyte population, the differentiation cycle, or the surface architecture directly – and those that act through the epidermis to reach their primary target in the dermis. This distinction matters because the epidermis is not a passive conduit; it responds to every treatment signal that passes through it, and understanding those responses determines how treatments are sequenced and combined.

Thulium Fractional Laser: Controlled Epidermal Renewal

Thulium 1927nm fractional laser is the most direct epidermal renewal treatment available. The 1927nm wavelength has a high affinity for water in the epidermis and superficial dermis, creating microscopic thermal zones (MTZs) that cover between 3% and 40% of the treatment area whilst leaving the surrounding tissue intact. This untreated tissue acts as a keratinocyte reservoir: neighbouring epidermal stem cells and basal keratinocytes migrate into the thermally treated zones and begin re-epithelialisation within 24 hours of treatment, completing epidermal recovery significantly faster than ablative resurfacing approaches that remove the entire surface. ^[5]

The clinical consequence of this mechanism is that thulium laser is simultaneously an epidermal disruption and an epidermal renewal stimulus. The wound-healing signal activates Wnt/β-catenin and TGF-β signalling in migrating keratinocytes, COL17A1 expression is preserved in the surviving follicular reservoir cells, and the differentiation cascade (profilaggrin production, lamellar body loading, lipid secretion) runs at its most active rate in the newly differentiating replacement keratinocytes. For aged, photodamaged, or perimenopausal skin where the renewal cycle has slowed and accumulated solar-damaged keratinocytes are producing poor-quality stratum corneum, this is the treatment most directly targeting the production system itself. It does not just resurface the skin, it resets the quality of the epidermal population generating the barrier. ^[11]

For pigmentation concerns, thulium’s epidermal precision makes it particularly effective: the MTZs directly target the superficial melanin deposits and accelerate the shedding of hyperpigmented cells, with the characteristic “coffee ground” appearance at 3–7 days reflecting the active clearance of fragmented melanin before it is shed in the renewal process. medicalphysics

LED Photobiomodulation: Driving Renewal from the Dermis Up

LED red light (630–660nm) contributes to epidermal renewal through a mechanism that runs in the opposite direction to most epidermal treatments. Rather than acting on keratinocytes directly, red light penetrates to the dermis and stimulates dermal fibroblasts via cytochrome c oxidase-mediated mitochondrial activation, increasing TGF-β and AKT signalling. The TGF-β stimulates collagen I production in fibroblasts; the accumulated collagen then activates integrin signalling in the overlying basal keratinocytes, which responds with increased proliferation and differentiation. The epidermis renews more actively because the dermal signal it depends on for differentiation cues has been strengthened. ^[1]

Research confirming that red light specifically accelerates recovery of the epidermal water-impermeable barrier (whilst blue light delays it) is particularly relevant for post-procedure protocols. Following any treatment that disrupts the epidermis, the renewal cycle driving barrier reconstruction is the process that determines recovery timeline and outcome quality. LED red light applied in the post-treatment period is not a passive adjunct; it actively accelerates the mitochondrial energy production and fibroblast-keratinocyte cross-talk that the renewal cycle depends on. ^[9]

Near-infrared (800–850nm) penetrates more deeply to the dermis and dermal-epidermal junction, while blue light (415nm) acts almost entirely within the epidermis. In the context of epidermal rejuvenation, the most practically relevant LED intervention is red light as a post-procedure recovery accelerant and as a standalone differentiation-normalising treatment for skin with slowed renewal.

Exosomes and Microneedling: Restoring the Epidermal Architecture

One of the structural changes in ageing skin that receives insufficient attention in aesthetic content is the flattening of the rete ridges – the interdigitating projections between the epidermis and dermis that increase dermo-epidermal surface area, facilitate nutrient and signal exchange, and help anchor the epidermis to its dermal substrate. As these flatten with age, the epidermis becomes more fragile, less well-nourished, and increasingly susceptible to the shear forces that cause easier bruising and skin tears.

Microneedling-assisted topical exosome therapy has demonstrated histological restoration of rete ridges alongside enhanced basal keratinocyte proliferation in aged skin biopsies. The mechanism is the combination of microneedling-created epidermal channels, which allow exosome cargo to reach the basal layer and dermo-epidermal junction, and the exosome miRNA and differentiation signals that activate the keratinocyte proliferation and matrix remodelling needed to rebuild the interdigitating architecture. Crucially, topically applied exosomes have been shown to be retained within the epidermis and superficial dermis for several hours post-application, providing a sustained interaction window for the regenerative cargo. ^[4]

Plant-derived exosome extracts have demonstrated restoration of SPTLC1 expression – the serine palmitoyltransferase subunit that initiates ceramide synthesis – in keratinocytes with inflammation-suppressed lipid metabolism, alongside reduced MMP-1 and increased procollagen expression. This makes exosome treatment, when delivered via microneedling channels, an intervention that simultaneously addresses epidermal architecture, ceramide synthesis capacity, and the collagen-mediated dermal signalling environment. No other single treatment combination addresses all three of these epidermal aging processes simultaneously. ^[3]

The note from the 2025 histological study warrants transparency: these findings apply specifically to microneedling-assisted topical delivery, not to injectable exosome formulations, which were not evaluated in the same study and whose epidermal effects cannot be inferred from these results. ^[4]

CAP, Polynucleotides, and Normalising the Epidermal Environment

Cold atmospheric plasma acts directly at the skin surface, with its RONS-mediated cytokine modulation operating primarily in the epidermis and superficial dermis. For the specific epidermal concern of acquired filaggrin suppression, CAP’s reduction of IL-4 and IL-13 at the tissue surface is the most anatomically targeted intervention. It does not stimulate the differentiation cycle directly, but it removes the cytokine signals actively suppressing it.

Polynucleotides, delivered intradermally, influence the epidermis through paracrine signalling: the macrophage reprogramming and fibroblast activation effects described in the collagen entity generate a dermal environment from which the overlying keratinocytes receive stronger differentiation and proliferation cues. Their epidermal benefit is indirect, but the dermal-epidermal cross-talk that red light also exploits means that improving the dermal signalling environment has genuine epidermal renewal consequences.

Treatment Pairings for Epidermal Rejuvenation

Thulium + LED (post-procedure): The most evidenced post-procedure pairing for epidermal renewal. Thulium creates the MTZ injury and activates the keratinocyte reservoir migration; post-procedure red LED accelerates the mitochondrial energy production and fibroblast-keratinocyte TGF-β signalling that completes the renewal cycle. Recovery timeline is shorter and differentiation quality is improved in the replacement keratinocytes compared with thulium alone.

Microneedling + exosomes (topical, same session): Channels created by microneedling allow exosome cargo to reach basal keratinocytes and the dermo-epidermal junction where rete ridge restoration occurs. This pairing addresses architectural renewal (rete ridges, basal proliferation) and biochemical renewal (SPTLC1/ceramide synthesis, MMP-1 reduction) simultaneously. The exosome application should follow immediately after needling whilst channels remain open.

CAP + exosomes: The inflammatory environment that CAP resolves at the tissue surface is the same environment that suppresses the differentiation programme exosomes are designed to restore. Sequencing CAP before exosome application – either in the same session or in a preparatory session – means exosome differentiation signals are delivered into keratinocytes whose FLG and SPTLC1 expression is no longer actively suppressed. For reactive, sensitised, or atopic-tendency skin, this sequencing addresses the epidermal renewal problem from both upstream and downstream simultaneously.

LED as a universal post-procedure adjunct: Across all injury-based epidermal treatments – thulium, microneedling, RF microneedling – post-procedure red LED reduces the inflammatory phase duration and accelerates the transition from inflammation to proliferation in the repair cascade. Given the slowed renewal rate in post-50 skin and the extended recovery timelines this implies, any intervention that accelerates the proliferative phase without compromising repair quality has practical value in this client group.