If you have been reading about regenerative aesthetics, JULÄINE™, or Ellansé, you will almost certainly have come across the word fibroblasts.
But what actually are they? And why does every conversation about regenerative skin treatment seem to come back to them?
Understanding what fibroblasts are and what they do will change the way you think about skin ageing entirely.
The cells that build your skin from within
Fibroblasts are specialised cells found throughout the connective tissue of the body. In the skin, they are found primarily within the dermis, where they play a central role in producing and maintaining components of the extracellular matrix that contribute to the skin’s structure and resilience.
One of their most important roles is the production and remodelling of collagen, including Type I and Type III collagen, which are particularly important within the dermis.
Type I collagen is the predominant collagen within adult skin and provides tensile strength and structural support.
Type III collagen is also present within the dermis and plays an important role in tissue organisation and repair. Together, these collagen types contribute to the strength and structural integrity of the skin.
Fibroblasts also contribute to the production and organisation of other components of the extracellular matrix, including elastin and glycosaminoglycans such as hyaluronic acid. Together, these components create the complex structural and biochemical environment in which skin cells function and communicate.
In short, fibroblasts are among the most important cells in the skin. They are the builders, the maintainers, and the repairers of the tissue we are most concerned with protecting.
What happens to fibroblasts as we age
Fibroblasts do not simply switch off as we get older. The biology is more interesting than that.
With age, the environment in which fibroblasts operate changes. Collagen fibres become increasingly fragmented and disorganised, signalling between the extracellular matrix and fibroblasts becomes less effective, and the balance between collagen production and degradation shifts. Hormonal change, cumulative UV exposure, oxidative stress and chronic inflammatory signalling can all influence this process.
The result is not simply “less collagen”. It is a gradual change in the quality, organisation and renewal of the skin’s structural framework.
This is one reason two people of exactly the same chronological age can present with very different skin. Age matters, but so do genetics, sun exposure, hormonal history, smoking, lifestyle and the biological environment those fibroblasts have been living in.
But chronological age is only part of the picture. UV exposure, hormonal change, smoking, genetics and the wider biological environment can all influence how skin ages. This matters clinically because I am not interested simply in whether a patient “has collagen loss”. I want to understand the environment in which that change has happened. A 42-year-old with excellent skin quality, minimal photodamage and very early change is a completely different clinical proposition from another patient of exactly the same age whose skin has experienced significant sun exposure, hormonal change or smoking.
The date on the birth certificate tells me something. The skin in front of me tells me much more.
In women, the menopausal transition can bring more noticeable changes in skin quality. Falling oestrogen levels influence collagen metabolism, dermal thickness and fibroblast behaviour, which is one reason skin ageing can become more apparent during and after menopause. You can read more about this in our guide to JULÄINE™ and menopause.
Fibroblast behaviour is also influenced by the surrounding inflammatory environment. Inflammageing, describes an age-associated tendency towards chronic, low-grade inflammatory activity, which can influence fibroblast behaviour and extracellular-matrix remodelling over time.
Why fibroblasts are central to regenerative aesthetics
Once you understand the role fibroblasts play in maintaining and remodelling the extracellular matrix, it becomes easier to understand why they feature so prominently in regenerative aesthetics.
Fibroblasts are one important part of the biological response we are interested in when using collagen-stimulating treatments. But they do not work in isolation. Tissue remodelling involves interactions between fibroblasts, the extracellular matrix, immune cells and the signals exchanged between them.
For patients, the important distinction is that different aesthetic treatments are designed to do different jobs. Hyaluronic acid fillers can replace or reshape volume. Botulinum toxin alters muscle activity. Collagen biostimulators are designed to create a tissue response that ultimately leads to fibroblast activity, new collagen formation and extracellular-matrix remodelling.
None is inherently more intelligent than another. The important question is which biological or structural change we are trying to address.
Not all collagen stimulation happens in exactly the same way
The phrase “collagen stimulation” can make these treatments sound interchangeable. They are not.
Different biomaterials have different compositions, particle sizes, shapes, surface characteristics and degradation profiles. These properties can influence how the surrounding tissue and immune system respond to them and, ultimately, how fibroblast activity and collagen remodelling occur.
With several established particulate biostimulators, a controlled tissue and immune response forms part of the pathway leading to new collagen formation. That does not make inflammation inherently “bad”. In normal tissue repair, inflammatory signalling can be an important part of the sequence that leads from an initial stimulus to remodelling and regeneration.
What matters clinically is the quality and duration of that response, the properties of the material being used, the evidence behind it and whether the treatment is appropriate for the patient.
JULÄINE™ is a PLLA collagen biostimulator using proprietary LASYNPRO™ microsphere technology. Its smooth, spherical microspheres are designed to stimulate a biological tissue response that leads to fibroblast activity and new collagen formation over time. Its particle design is of particular interest because the physical characteristics of an injectable biomaterial can influence how it interacts with surrounding tissue and immune cells. Preclinical and emerging evidence cited by Nordberg Medical suggests that JULÄINE’s microsphere design is associated with a low-inflammatory tissue response. Ellansé uses biodegradable polycaprolactone microspheres suspended in a carboxymethylcellulose gel carrier. The gel provides an initial corrective effect, while the PCL microspheres are associated with progressive collagen formation and tissue remodelling over time.
Sculptra is another PLLA-based collagen biostimulator. Its particles produce a controlled tissue response involving immune-cell signalling and subsequent fibroblast activity, leading to gradual new collagen formation over time.
Sunekos uses a patented combination of amino acids and hyaluronic acid designed to support extracellular-matrix regeneration and skin quality through a different biological approach.
For me, the important point is not that inflammation is absent, or that one pathway is inherently “better”. It is that biomaterial design matters, and as clinicians we should understand the biology behind the products we use rather than treating every collagen stimulator as interchangeable.
Inflammageing and fibroblast function
One of the most important factors influencing fibroblast activity is inflammageing. This is the chronic low-grade inflammation that accumulates as we age.
Chronic inflammatory signalling can alter fibroblast behaviour and extracellular-matrix remodelling, while oxidative stress and cellular senescence can further influence collagen homeostasis. Over time, these processes may contribute to changes in skin structure and function associated with ageing.
This is why the most effective approach to skin longevity is never simply about injectable treatments. This is also why a skin-longevity strategy extends beyond injectable treatment. Daily sun protection, not smoking, appropriate skincare and attention to wider health all form part of protecting the biological environment in which skin ages. Supporting fibroblast function means supporting the broader conditions in which skin can regenerate well.
Can you “wake up” ageing fibroblasts?
You will sometimes hear regenerative treatments described as “waking up” dormant fibroblasts. It is a useful visual metaphor, but biologically it is an oversimplification.
Fibroblasts remain present throughout life, but their behaviour is influenced by ageing, the extracellular matrix around them, hormonal signalling, UV exposure, inflammation and other aspects of the tissue environment.
Collagen-stimulating treatments aim to create biological signals that encourage new collagen formation and tissue remodelling. That is more accurate than imagining that ageing fibroblasts have simply gone to sleep and need switching back on.
And importantly, injectable treatment is only one part of the picture. Protecting skin from UV exposure, avoiding smoking and looking after general skin health remain fundamental because the environment around the fibroblast matters too.
What this means in practice
Understanding fibroblasts does not require a biology degree. What it requires is a shift in how you think about skin ageing.
Rather than seeing ageing only as a series of isolated problems to correct – a line here, some volume there – you begin to see the skin as part of a changing biological system. That does not remove the role of corrective treatments. It simply gives us more information with which to decide what, if anything, needs treating.
At Mediject, this understanding shapes every recommendation we make. It is why we think about collagen banking as a long-term strategy rather than a single treatment decision. And it is why every consultation begins not with a product but with a conversation about how your skin is ageing and what it genuinely needs.
Frequently asked questions
Can you increase fibroblast activity through lifestyle alone?
Healthy skin is influenced by many factors. Daily sun protection, avoiding smoking, appropriate skincare, nutrition and wider health all contribute to the environment in which skin ages. Lifestyle cannot stop biological ageing, but neither should injectable treatment be presented as necessary simply because fibroblast behaviour changes over time. Collagen-stimulating treatment may be considered where there is a clinical indication and the patient wishes to explore it.
Do all collagen stimulators work the same way on fibroblasts?
No. Different collagen biostimulators use different biomaterials, particle characteristics and degradation profiles, and these influence how they interact with surrounding tissues. Controlled tissue and immune responses form part of the pathway leading to collagen formation with several established biostimulators. JULÄINE™ has been designed with smooth, spherical PLLA microspheres, with emerging evidence suggesting a relatively low-inflammatory tissue response. Treatment selection should be based on the properties, evidence and suitability of the individual product rather than assuming all collagen stimulators behave identically.
At what age should I start thinking about supporting fibroblast activity?
There is no fixed age. Skin biology changes gradually throughout adult life, but the way those changes become visible varies considerably between individuals. For some patients, changes in skin quality in their thirties may make collagen-stimulating treatment worth discussing. For others, the priority may remain daily SPF and evidence-based skincare rather than injectable treatment. The decision should be based on the skin in front of us rather than a predetermined age bracket.
Is there a way to assess fibroblast activity in my skin?
Not directly in a routine aesthetic consultation. We can assess the clinical characteristics of the skin – including texture, firmness, elasticity, photodamage and other signs of tissue ageing – but this is not the same as directly measuring fibroblast activity. At Mediject, these clinical findings are considered alongside age, medical history, hormonal change, previous treatments and the patient’s goals when deciding whether collagen stimulation has a role.
Fibroblasts may sound like a technical detail, but understanding their role gives us a much richer picture of how skin maintains and remodels itself over time.
At Mediject, understanding that biology is not an academic exercise. It helps us ask better questions about why a patient’s skin is changing, what remains worth preserving and whether treatment has a role at all.
Because once we understand what is changing beneath the surface, we can make a much more intelligent decision about what, if anything, needs treating.
