PN vs PDRN — Is Rejuran the Same as a Salmon DNA Injection?

Three-line summary

• The Rejuran Healer we hold at ABLE Dermatology contains PN (polynucleotide), while the group commonly called salmon DNA injections in Korea contains PDRN (polydeoxyribonucleotide). Both come from salmon, but they are taken from different parts of the fish and their chains are not the same length.
• The two share the same adenosine A2A receptor pathway, but PN, with its higher molecular weight, adds a physical scaffolding role and a longer duration. Their Korean regulatory categories differ as well: PDRN is a prescription drug, PN a biomaterial for tissue repair.
• In acne scarring, the widest range of benefit sits with immature scars that still look red. Hardened icepick and boxcar scars are not resolved by injection alone, and are planned in sequence with Potenza (microneedle RF), fractional CO2 and subcision.

PN and PDRN are both DNA fragments that come from salmon

Both are DNA-derived polymers that have drawn attention in wound healing and skin regeneration since the 1990s. In order of appearance, PDRN came first. It has been used in clinical practice far longer, to move the stages of wound healing along rather than for aesthetic purposes, and its wider use is the more recent development. Rejuran, the representative product on the PN side, launched in Korea in 2015.

A material of the same family exists in human placenta, but ethical issues make it difficult to use, and fish-derived sources are understood to have taken its place as the alternative. That is why both substances start from salmon.

They are extracted from different parts of the fish

• PDRN — a DNA material extracted from salmon sperm, that is, the seminal fluid.
• PN — a DNA material extracted from salmon testes.

The conditions for obtaining the raw material are demanding. A single salmon yields around 10–15 ml of seminal fluid, or about 80–100 g from the testes, and it takes roughly 1 kg of seminal fluid to make around 5,000 vials of product. On top of that, germ cells are not active at sea, so the material has to be secured at the point when the fish run upriver to spawn. This shared starting point is part of why two substances with similar names end up grouped together.

Where PDRN was first used was not aesthetics

For a long time, the place PDRN occupied was wound healing itself. A wound heals through an inflammatory phase, a proliferative phase and a maturation phase in turn. When that sequence fails to run smoothly and stalls at one stage, or overshoots, the trace it leaves behind is a scar. PDRN first established itself in clinical practice as a way of driving those phases along, and aesthetic use widened afterwards.

Once you know that order, both materials look slightly different. PN and PDRN were not designed from the outset to make skin look better. They started as materials that intervene in the process by which tissue heals. The use in scarring we come to below is closer to where this family began, and it is easier to understand pores, fine lines and deep dryness as the same action showing up in an aesthetic setting.

What divides them is chain length, which is to say molecular weight

PN and PDRN are both polymers made up of DNA fragments. The molecular weight range generally quoted is 50–1,500 kDa, though recent work has reported fragments across a far wider spread, from 1 kDa up to 10,000 kDa. Two names, with a broad band where the substance overlaps — which is why PDRN and PN were at times used interchangeably in the past.

So a proposal has since been put forward to separate the two using molecular weight as the dividing line. It is a proposal, and not every source follows that line, which is worth knowing alongside it. Even so, the fact that the move to keep the two names apart is being organised around molecular weight is useful in itself.

What the unit kDa actually means

A kDa is a unit for the weight of a single molecule. A DNA fragment is a chain of units called nucleotides, so saying the molecular weight is high is close to saying the chain is long. Two products can come from the same raw material and still differ in weight, depending on how short the chains were cut, and what they do inside the body differs with it.

Short fragments diffuse quickly and spread widely, but they do not hold their place for long. Longer chains tangle with one another, take on gel-like properties, and stay at the injected site holding their shape. It is closer to reality to understand the difference between the two as a property that diverges with chain length than to look for it in a name on an ingredient list.

A long chain also means each molecule is that much heavier, so the amount of active ingredient held in the same volume changes a great deal. Some PDRN ampoules on the market hold a little over 5 mg of active ingredient in 3 ml, while Rejuran holds 40 mg of PN in 2 ml. The numbers look far apart, but this is more accurately read as a difference produced by formulating molecules of different size for different purposes, rather than as a ranking of potency.

Setting the two side by side in milligrams therefore invites misreading. A heavy molecule gives a large mg figure even at the same count, and a light one fits far more molecules into the same mg. A high content figure cannot be read as a regeneration signal that much stronger, and a low one cannot be read as an effect that much weaker. What deserves comparison is not the number but what that material was built to do in that particular place.

Even under the Rejuran name, the content is not the same

The Rejuran range ABLE Dermatology holds is Rejuran Healer (PN), Rejuran HB+ (PN+HA), and Rejuran I, which is for the under-eye area.

• Rejuran Healer · Rejuran I — the PN content per ml is the same, and only the viscosity differs. We choose between them to match the site and the depth of injection.
• Rejuran HB+ — the PN content per ml is halved, and hyaluronic acid and an anaesthetic are included instead. The weight of the formulation sits on immediate hydration and on comfort during the procedure.

Under one Rejuran name, then, the amount of PN actually delivered depends on which one you had. Without checking that far, it is hard to explain why the Rejuran you had last time and the Rejuran you had this time did not give the same result.

They share the pathway, and PN adds one thing to it

Inside the skin, PN and PDRN break down into smaller DNA fragments, and those fragments stimulate the adenosine A2A receptor on fibroblasts. When the receptor is stimulated, cAMP rises inside the cell, and that leads on to activation of protein kinase A (PKA). PKA is a signal involved directly in cell growth, survival and differentiation, and what appears as a result is angiogenesis, reduced inflammation and collagen synthesis.

Put together, the effects the two share are faster wound healing, less inflammation, and change in the direction of skin regeneration and anti-ageing. Up to this point, PN and PDRN tell effectively the same story. It is also the reason the two are so often understood as one thing.

What those three effects mean in the skin

• Angiogenesis — blood flow has to reach a site that needs to heal before material and oxygen can be supplied. A site where a scar heals poorly is usually short of that supply.
• Reduced inflammation — inflammation that drags on works, in itself, to enlarge the scar. Settling the inflammation leads, in the end, towards less scarring left behind.
• Collagen synthesis — the material that refills a collapsed area gets made. But this is only a signal to make material; it is not a signal that unpicks a structure that has already set in the wrong arrangement.

That last item matters. Materials in this family work in the direction of helping tissue whose healing is still in progress; they do not work in the direction of dismantling a finished structure and rebuilding it. The way we divide scars up further down comes from exactly this.

PN adds a scaffolding role

• Viscoelasticity — with its higher molecular weight, PN settles into tissue as a gel and stays at the injection site for a period. PDRN does not have this property. It is not, however, used like a volumising filler: the purpose and the volumes involved are different.
• Hydration — PN binds water molecules readily, so it works towards creating a moist environment at the injected site.
• Duration — being a large polymer, it stays in the skin longer, and the effect tends to carry on for longer with it.
• Pain — it comes as a gel and it has viscosity, so the pain felt on injection is generally greater with PN than with PDRN. It is not a property with advantages only.

This is also where the split in Korean regulatory categories comes from. PDRN is a prescription drug — classified as a drug ingredient, literally — and the indication approved by Korea's Ministry of Food and Drug Safety is the treatment of wounds from skin grafting, and tissue repair. PN, by contrast, is classified as a biomaterial for tissue repair, that is, a medical device. Its larger molecular size gives it a physical scaffolding effect on top of the established PDRN effects, which is also why it is used in areas such as joint cartilage regeneration and promoting bone formation. Two materials from the same root sit in different legal categories.

The row to watch in that table is the third. The pathway that generates the regeneration signal is the same for both. Where they part is below it, in what the material goes on to do once it stays in place. So for the same goal, either one sets the direction in much the same way, and at the moment a supporting role is needed, the options narrow to one side.

Why salmon DNA injections and Rejuran get grouped together

In Korea, salmon DNA injection is used as an everyday expression pointing to PDRN-based injectables. It is not a formal classification but a nickname that attached itself in the Korean market because the raw material comes from salmon.

The difficulty is that PN, the ingredient in Rejuran, comes from the same salmon. The raw material is the same, the receptor pathway it acts on after breaking down is the same, and the intended direction — regeneration, less inflammation, collagen — overlaps as well. So in the consultation room salmon DNA injections and Rejuran come up together naturally, and some patients arrive understanding them as one and the same procedure.

Still, it is better to keep them apart by classification. The Rejuran Healer ABLE Dermatology holds contains PN, and not PDRN. The two differ in the molecular weight standard applied to them, differ in regulatory category, and differ in whether the scaffolding role is there. This is not a claim that one is better than the other; it means they are different materials used for different purposes. Separately from Rejuran on the PN side, ABLE Dermatology also runs PDRN regenerative injections, and we use them apart from one another according to the goal.

The goal decides which one to use

• When material needs to stay in a depression — what is needed is a material that remains in the tissue for a period after injection, so PN, with its higher molecular weight and viscoelasticity, comes into the plan.
• When recovery over a broad area and barrier stability are the goal — PDRN becomes the option, with its low viscosity making it easy to spread widely and lighter to sit through.
• When the two are used together — rather than stacking them for the same purpose, we place them across different layers and areas so their roles do not duplicate each other.

This is why the names being mixed up does not end as a simple matter of terminology. The two differ in formulation, in the dose required, and in how sessions and intervals are set. Build a plan on the understanding that salmon DNA injections and Rejuran are the same thing, and the change you expect and the material you actually received are easily out of step. What to establish first at the consultation is not the name but whether what is needed now is a regeneration signal, or a supporting role on top of it.

What you can expect in acne scarring

The pathway running from the A2A receptor through to PKA is, in the end, a signal that intervenes in the process by which tissue heals. So the scars where PN and PDRN have the most room to work are not scars that are already finished and hardened, but immature scars still in the process of becoming scars.

• Acne scars where redness remains
• Red scars following an injury
• Scars where the healing process is still under way, such as burn scars

What separates an immature scar from a mature one

The first thing we look at when dividing the two in clinic is colour. Redness remaining means the vessels at that site are still dilated and the healing response is still running. At this stage, how the tissue will settle is not yet decided, so there is still room for adding a regeneration signal to influence the outcome.

A scar whose redness has drained and settled to the same colour as the surrounding skin, by contrast, is closer to a structure that has already set. Adding more signal at that point does not loosen an arrangement that has hardened. It is why the plan changes according to the stage you are at, even when patients arrive under the same name of acne scarring.

The reported cases cluster in this range too. PDRN was originally used for wound healing, so reports of its use on scars are not numerous in themselves, but there is a case report of PDRN used on a hypertrophic scar that had progressed as far as contracture after a skin graft. At 12 months from the start of treatment, the report describes improvement in the texture of the scarred area and substantial resolution of the redness (Belmontesi M, J Cosmet Dermatol, 2020). That case too falls under an immature scar with a red look still present, and it is noted alongside that the result would likely have been better had treatments such as fractional laser or pinhole been carried out with it.

On the PN side, reports relating to scars are comparatively more numerous. A study gathering cases in which a PN preparation was applied two or three times, or several times over, to a range of scars — facial trauma scars, scars after breast surgery, dog-bite scars — observed change in the direction of improvement in scar texture and erythema in most of them (Kim MJ et al., J Dermatolog Treat, 2024). A randomised, double-blind controlled study has also been published comparing a PN-treated group and an untreated group over 16 weeks in thyroid surgery scars, using 3D imaging (Kim JH et al., Lasers Surg Med, 2018).

A scar in the making, rather than one already there

What is interesting about that thyroid surgery scar study is that it was designed from the standpoint of prevention rather than treatment. Not reversing a scar that is already finished, but intervening during the period in which the scar is being made, to reduce how much is left behind. The place where the PN and PDRN family is at its most convincing is close to this.

Moved across to acne, this becomes quite concrete. The red mark left just after inflammatory acne settles is an undecided window: it may harden into a scar, or it may pass as a mark. Clear the inflammation in that window and add a healing signal, and there is room for it to work in the direction of minimising scar formation. Come in after that period has been let go, by contrast, and the range the same materials can cover narrows noticeably.

This too varies from person to person, and if acne keeps coming up repeatedly, treatment to reduce the inflammation comes before dealing with the marks. However much healing signal you add, results do not accumulate at a site where new inflammation keeps appearing.

In atrophic acne scars — that is, depressed ones — the grounds for actively considering PN come from one more thing attaching here. On top of the general wound-regeneration effect PDRN has, PN adds the property of staying at the injection site for a period. While the material remains in a sunken site, that space becomes easier for tissue to fill, and being a large polymer, that state tends to hold for longer. This is not the same purpose as a volumising filler. It is the same reason that, when PDRN is used on a scar that needs filling up, it is sometimes mixed with hyaluronic acid to make up for the scaffolding role.

On nodule formation, concern around the PN and PDRN group is understood to be comparatively lower than with the other collagen-stimulating materials used on scars. PDRN goes through extraction and purification at very high temperatures, which inactivates proteins and peptides. That does not mean no reaction at all occurs, however: temporary swelling or bruising can appear depending on the depth and the site of injection, and the course varies from person to person.

What is harder to expect — the scars injection alone does not reach

Read this far and it can feel as though several rounds of Rejuran will sort acne scarring out. That is not the case. The evidence above sits mostly with immature scars where redness remains, with prevention and minimisation during the process in which a scar is made, and with shallow, gentle depressions. Scars whose shape has already set are a different story.

• Icepick scars — the structure drives in narrow and deep, so an injected material does not reverse that shape. Approaching the structure itself with dot peel (TCA CROSS) or a CO2 laser comes first.
• Boxcar scars with sharp borders — the walls stand vertically, so the work of bringing the height into line with the surrounding tissue is needed. Treatments that address the edges, such as fractional CO2 or pinhole, form the axis.
• Rolling scars with firm tethering — the floor is held down by the tissue beneath, so unless that tethering is released first, whatever you put in gets pressed down again. Subcision takes this role.
• Old, mature scars — the room left to respond to a regeneration signal has narrowed, so the degree of change expected in an immature scar is hard to expect on the same terms.

So in scar treatment, the place of PN and PDRN is generally not the lead role on its own but a place paired with treatments that address structure. Potenza (microneedle RF) delivers radiofrequency to a target depth from fine needles without passing through the surface, and works on the fibrous tissue under the scar. Fractional CO2 creates fine thermal injury from the surface down into the dermis and drives remodeling. Subcision physically releases a floor that is stuck down. PN and PDRN add a regeneration signal on top of the healing process these treatments have opened up, work in the direction of reducing redness, and hold a depressed site up for a period.

Conversely, a plan that repeats only one side tends to satisfy less. Repeat only the treatments that address structure and healing cannot keep pace, so redness lingers; repeat only the injections and the hardened structure stays as it is. What divides the outcome is setting the sessions, the intervals, and which treatment to place first, to match the shape and the maturity of the scar. Results vary from person to person.

It is better to align expectations first

Acne scarring, in most cases, means several types mixed together on one face. A red mark, a shallow dip, a boxcar with a standing edge and a narrow, deep icepick sit together on one cheek. Of these, the share PN and PDRN can take on is part of the whole, and the rest belongs to other treatments.

So at the consultation we first set out separately which scars this plan can change, and which move on to the next stage. Start without that distinction and it is easy to be left with the feeling that things fell short of expectation, even though the plan was in fact followed. In scar treatment, aligning expectations affects the outcome as much as the procedure itself.

How we divide their use at ABLE Dermatology

We look at the maturity of the scar first. Whether redness remains, whether the floor follows when the skin is stretched, what shape the border takes — the plan differs on these points even for the same acne scarring. The order is not to pick a material first and then fit the scar to it.

There are four things we check in clinic. Whether redness remains in the scar; whether the floor follows when the skin is pulled sideways (if it does not, that is a sign of tethering); whether the border stands or slopes; and whether inflammatory acne is still coming up. If the fourth is still there, treatment to reduce the inflammation comes before the scar plan.

• Rejuran Healer (PN) — used when regeneration and skin texture are the goal, and when the material needs to stay in a depressed area for a period.
• Rejuran HB+ (PN+HA) — with half the PN content, and hyaluronic acid and an anaesthetic included instead, it is chosen when the weight is on hydration and on comfort during the procedure.
• Rejuran I — a formulation for areas where the skin is thin and the surface small, such as under the eyes.
• PDRN regenerative injection — used when recovery over a broad area and barrier stability are the goal, or when the burden of the injection has to be kept low.
• Synerjet (needle-free injection) — considered as a delivery method when needle injection is difficult, or when a wide area needs a shallow, even layer.

The same dose is not the same, depending on where it was placed

We do not divide the injection up evenly either. Rather than placing the same amount over the whole face at set intervals, we take the order of injecting first into the areas that are depressed or need volume restored, and then laying a thin layer over the whole. The same holds when scar treatment is not the goal, because the same dose gives a different result depending on where and how much was placed.

People sometimes judge Rejuran by how densely the injection marks were laid down. But an injection mark is only a trace showing, briefly, where the material went in, and it settles within a few hours to a day. What remains is not the number of marks but at what depth, in what place, and how much went in. Divide the same dose evenly across the whole face and the amount going back to the site that actually needs supporting goes down.

Depth changes with the goal as well. If hydration of the skin texture is the goal, we lay a thin layer in the shallow plane; if supporting a depressed site is the goal, we place it so it sits beneath that. The same product at the same dose gives a different result if this design differs, so it is worth looking at how it was placed as much as at what you had.

When the scar is the main goal, we do not build the plan on injection alone. Depending on the shape and depth of the scar, we set Potenza, fractional CO2, pinhole, dot peel (TCA CROSS) and subcision as the axis, and if redness remains alongside, include V-Beam as well before deciding the order, then place PN or PDRN in between. How to arrange the treatments that need recovery time against those that do not becomes the frame of the whole schedule.

Recovery time is what we use as the basis for setting the order of treatments. Treatments that crust the surface, such as fractional CO2 or pinhole, need recovery time, and we do not overlay injections during that period. Place PN or PDRN once recovery has progressed to a degree, by contrast, and the regeneration signal lands on top of that process. More often than which treatment comes first, the practical issue in scheduling is how much interval to leave between the two.

To add, PDRN is known for improvement in skin texture, for wound healing and regeneration through increased DNA synthesis, for pigment improvement in the direction of interfering with tyrosinase, and for hair improvement. These items, though, are a different matter from scar treatment, and it does not mean one injection resolves every concern together. How the same material is used changes according to what you set as the goal.

From consultation to procedure

A board-certified dermatologist examines you directly, identifies the layer the cause sits in, decides the device and the parameters, and the same dermatologist carries on to perform the procedure. This is not a structure in which a consultant recommends the treatment.

Sessions, intervals, maintenance timing and cost are agreed together before the first procedure.