Creative Touch Permanent Makeup and Aesthetics

Fibroblast Growth Factors (FGF) are a family of 22 signalling proteins that act as the skin’s primary “signalling currency” for repair and regeneration. In clinical aesthetics, we focus on a specific quartet: FGF2 (angiogenesis and collagen), FGF7 and FGF10 (the dermal-epidermal communication axis), and FGF21 (inflammatory resolution). FGFs are not freely circulating; they are sequestered within the extracellular matrix (ECM) bound to Heparan Sulphate Proteoglycans (HSPGs). Therefore, the efficacy of FGF-based treatments like iPRF is entirely dependent on matrix integrity. In an MMP-degraded dermis, the “reservoir” is broken, leading to poor growth factor retention and attenuated treatment results.

Fibroblast growth factors are a family of 22 structurally related signalling proteins, ranging from 17 to 34 kDa in molecular weight, that act through four tyrosine kinase receptors – FGFR1 through FGFR4 – to regulate cellular proliferation, migration, and differentiation across mesodermal, ectodermal, and endodermal cell lineages. ^[1] Despite the name, FGFs are not exclusively fibroblast-acting. The name reflects their original discovery context rather than their full biological scope. In skin specifically, the active family membership is considerably narrower than the full 22-member family: FGF2, FGF7, FGF10, and FGF21 are the dominant isoforms expressed and functional in skin tissue. ^[7] Understanding what each of these four does, and what happens when their activity declines, is more clinically useful than treating the family as an undifferentiated whole.

The Four Skin-Dominant FGF Members

FGF2 (basic FGF, bFGF) is the most extensively characterised member in skin biology. It is released by damaged endothelial cells and macrophages at wound sites and acts on dermal fibroblasts to stimulate proliferation, migration, and collagen synthesis through ERK, AKT, and STAT1 phosphorylation in a concentration-dependent manner. academic.oup.com FGF2 is also a potent angiogenic factor – if FGF2 activity is blocked, wound angiogenesis is almost completely impaired. ^[8] In wound healing, FGF2 accelerates closure by promoting keratinocyte epithelial–mesenchymal transition (EMT) in combination with TGF-β1, though importantly, FGF2 alone does not activate EMT in keratinocytes; the co-stimulus of TGF-β1 is required. ^[4] This co-dependency with TGF-β1 is clinically relevant to the iPRF context, where both growth factors are delivered simultaneously within the same preparation.

FGF7 (keratinocyte growth factor, KGF) acts exclusively on epithelial cells. It is the only FGF family member with this restricted specificity, at least in adult tissue. ^[1] Produced by dermal fibroblasts and epidermal γδ T cells, FGF7 signals in a paracrine direction from the dermis upward to keratinocytes, stimulating their migration, proliferation, and differentiation. rupress.org This fibroblast-to-keratinocyte signalling axis is part of the broader dermal–epidermal communication infrastructure that maintains epidermal homeostasis and coordinates wound re-epithelialisation.

FGF10 (KGF-2) shares FGF7’s keratinocyte-stimulating role. It is produced by fibroblasts in the dermal papilla and interfollicular dermis and signals parabolically to epidermal keratinocytes through FGFR2IIIb. rupress.org FGF10 and FGF7 have overlapping but distinct binding affinities for heparan sulphate – FGF7 binds less tightly to the ECM matrix, making it more diffusible, whilst FGF10 is more ECM-retained and acts across shorter distances. ^[6] This structural difference in ECM binding governs how far and how fast each signal travels through tissue, which matters for the spatial organisation of epidermal repair.

FGF21 is the most recently characterised skin-relevant member. It promotes fibroblast motility, accelerates wound closure, and through the JNK signalling pathway reduces local inflammatory mediators whilst enhancing collagen synthesis and vascular network formation at wound sites. ^[5] FGF21’s combination of anti-inflammatory and pro-synthetic activity makes it mechanistically interesting in the context of treating skin where chronic inflammation has suppressed fibroblast output, though its specific therapeutic applications in aesthetic medicine remain at early research stage.

The Skin-Specific FGF Quartet

The ECM Reservoir: Why Matrix Health Affects FGF Availability

One of the most clinically significant and least discussed aspects of FGF biology is that most FGFs are not freely circulating in tissue fluid. They are stored bound to heparan sulphate proteoglycans (HSPGs) in the extracellular matrix, where they are held in an inactive but protected form, available for rapid release when tissue injury or enzymatic activity creates local demand. sciencedirect.com FGF2 in particular binds to the HSPG perlecan in the dermal ECM – binding that is entirely heparan sulphate-dependent and completely blocked when heparan sulphate-degrading enzymes are applied. ^[3]

The clinical consequence is that the integrity of the dermal ECM is not simply a structural matter but a determinant of FGF availability. When MMP-driven collagen fragmentation and proteoglycan degradation progressively erode the ECM in aged or photodamaged skin, they simultaneously deplete the heparan sulphate-proteoglycan binding sites that hold FGF2 and other growth factors in the tissue reserve. The dermis becomes structurally thinner and simultaneously less well-stocked with the repair signals it would need to respond to injury. This is a compounding deficit: reduced ECM means reduced FGF reservoir means reduced regenerative capacity, which in turn produces less collagen synthesis to replenish the ECM. The MMP entity describes the structural side of this loop; FGF availability is the signalling-reservoir side of the same story.

The “Reservoir” Logic

FGF Signalling and Cellular Senescence

Beyond wound healing and collagen synthesis, FGF signalling plays an active role in maintaining fibroblast proliferative capacity and resisting cellular senescence. FGFs promote self-renewing proliferation and inhibit cellular senescence in nearly all tissues tested, and reduced FGF signalling is associated with accelerated senescence entry in fibroblast populations. ^[2] In ageing skin, where the dermal fibroblast population is both smaller in number and progressively accumulating senescent cells, declining FGF signalling capacity – driven by reduced ECM reservoir, reduced FGFR expression, and reduced platelet-derived FGF release from declining platelet counts – contributes to the self-reinforcing cycle of fibroblast senescence and reduced ECM production that the Fibroblast entity describes in detail.

FGF and the FGFR1/FGFR2 Barrier Axis

A less obvious but mechanistically important FGF function in skin is FGFR1 and FGFR2 signalling in keratinocytes. This controls tight junction integrity, epidermal barrier function, and skin appendage maintenance through regulation of claudins and other tight junction components. rupress.org The responsible FGF ligands are FGF1, FGF7, FGF10, and FGF22, expressed in different skin compartments and signalling across the DEJ from dermis to epidermis. This connects FGF signalling not only to the structural dermis but to the epidermal barrier function discussed in the Stratum Corneum, Filaggrin, and Ceramide entities. This is a less-appreciated route through which declining FGF signalling in aged dermis contributes to epidermal barrier deterioration above it.