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sh-Polypeptide-1 for Hair Regrowth

Evidence Review created on 09/27/2026 using AI4L / Opus 5.5

Also known as: Basic Fibroblast Growth Factor, bFGF, Fibroblast Growth Factor 2, FGF2, FGF-2, Recombinant Human Basic Fibroblast Growth Factor, rh-bFGF, Trafermin, Fiblast

Motivation

The cosmetic ingredient sh-Polypeptide-1 (basic fibroblast growth factor) is a lab-made copy of a human signaling protein that helps repair skin and grow new blood vessels. It now appears in scalp serums and clinic treatments marketed for thinning hair, based on the idea that it can nudge resting hair follicles back into their growth phase.

Thinning hair affects many men and women from midlife onward, and the standard medicines require daily, open-ended use that many people want to strengthen or supplement. The same protein has been sold as a prescription wound-healing medicine in Japan and China for over two decades, and small clinical studies from Asia report denser hair when it is added to standard hair-loss treatments.

This review examines what the evidence shows about sh-Polypeptide-1 for hair regrowth: how it acts on the hair follicle, how strong and how applicable the human data are, whether a large protein applied to the scalp reaches its target, what risks it carries, and how it is used in practice.

Benefits - Risks - Protocol - Conclusion

This section lists expert commentary and primary research on growth-factor approaches to hair regrowth relevant to sh-Polypeptide-1, which is recombinant human basic fibroblast growth factor (bFGF).

Content from Rhonda Patrick (FoundMyFitness), Chris Kresser and Lifespan.io is not included: web and on-site searches found no material from them discussing sh-Polypeptide-1, bFGF, or growth-factor scalp treatments. Peter Attia’s member-only AMA #63 on hair loss is not included because its full content is available only to paying members; his freely accessible hair-restoration episode is listed instead.

Grokipedia

  • Fibroblast growth factor 2

    Dedicated article on FGF2 (bFGF), the protein sold as sh-Polypeptide-1, covering its structure, receptor binding, roles in wound healing and blood-vessel growth, and context-dependent involvement in cancers such as melanoma.

Examine

No Examine article on sh-Polypeptide-1 or basic fibroblast growth factor exists.

ConsumerLab

No ConsumerLab article on sh-Polypeptide-1 or basic fibroblast growth factor exists.

Systematic Reviews

This section lists systematic reviews and meta-analyses covering bFGF within hair-loss regimens and the safety of topical FGF2 and other growth factors.

No systematic review evaluates sh-Polypeptide-1 as a leave-on cosmetic serum: the benefit evidence comes from reviews of combination regimens, and the risk evidence from topical FGF2 and growth-factor use on wounds.

Mechanism of Action

sh-Polypeptide-1 is the INCI (International Nomenclature of Cosmetic Ingredients) name for recombinant human bFGF (FGF2), an 18 kDa (kilodalton, a unit of molecular mass) protein made in Escherichia coli.

  • Receptor signaling: bFGF binds fibroblast growth factor receptors (FGFRs, cell-surface receptors triggering growth signals), mainly FGFR1, with heparan sulfate (cell-surface sugar chains) as co-receptor, activating MAPK/ERK (a cell-division signaling chain) and PI3K/AKT (a cell-survival pathway).
  • Follicle effects: It stimulates dermal papilla cells (the signaling cluster at the follicle base that directs hair growth) and preserves their follicle-inducing capacity in culture (Kiso et al., 2015). In mice, it moves telogen (resting) follicles into anagen (growth) via Wnt/β-catenin (the main switch that starts a new hair cycle) (Lin et al., 2015).
  • Blood supply: It drives angiogenesis (new blood-vessel growth) around follicles.
  • Competing evidence: Injected bFGF delayed follicle development in newborn mice (du Cros, 1993), so effects may depend on dose and timing.
  • Tissue distribution: At 18 kDa it far exceeds the roughly 500-dalton ceiling for passive skin penetration (Bos & Meinardi, 2000); serums likely reach follicles only via follicle openings or microneedling, with negligible blood levels.
  • Half-life and metabolism: After intravenous dosing, distribution half-life is 21 minutes and terminal half-life 7.6 hours (manufacturer Chiron data) (Bush et al., 2001). Proteases (protein-cutting enzymes), not cytochrome P450 (CYP, the main drug-metabolizing liver enzymes), degrade it; it loses activity at body temperature without a carrier (Takabayashi et al., 2016).

Historical Context & Evolution

  • Discovery: Basic fibroblast growth factor was isolated from bovine pituitary tissue in the 1970s as a factor that made fibroblasts (connective-tissue cells) divide; the human gene was cloned in the mid-1980s.
  • Original intended use: Wound healing. Recombinant bovine bFGF was approved in China in the late 1990s for burns and wounds, and recombinant human bFGF (trafermin, Fiblast Spray) in Japan in 2001 for pressure and skin ulcers. A 600-patient burn trial found faster healing (Fu et al., 1998).
  • Cardiovascular and stroke trials: Around 2000, intravenous and intra-arterial bFGF was tested to grow heart blood vessels and aid stroke recovery; benefits were not confirmed, and blood-pressure drops appeared (Bogousslavsky et al., 2002).
  • Hair research: Early mouse work found injected bFGF delayed hair follicle development (du Cros, 1993); later mouse studies found topical FGFs triggered the growth phase, and bFGF became standard for keeping dermal papilla cells functional in culture (Osada et al., 2007).
  • Move into hair care: From the 2010s, Asian clinics combined bFGF with microneedling, PRP, and minoxidil, reporting denser hair in small trials, while cosmetics makers added sh-Polypeptide-1 to scalp serums.
  • Current standing: Neither the early negative mouse finding nor the later positive trials settles the question. What changed was delivery (needling, carriers) and combination use; controlled trials of cosmetic serums remain absent.

Expected Benefits

High 🟩 🟩 🟩

Denser hair in pattern hair loss when added to standard treatment

In androgenetic alopecia (AGA, hereditary pattern hair loss), adding bFGF to minoxidil (a topical hair-growth drug) or PRP improved hair counts or photographic ratings beyond the comparator in three randomized controlled trials (RCTs, trials assigning treatment by chance) (Liu et al., 2022; Yu et al., 2020; Qu et al., 2023); a fourth found PRP-plus-bFGF with minoxidil beat either alone (Wu et al., 2023). Microneedle-delivered bFGF alone raised density; saline did not. Trials were small, short, Chinese, inconsistently blinded, and used pharmaceutical bFGF by needling, injection, or spray, not cosmetic serums.

Magnitude: Microneedle bFGF plus minoxidil raised density from 101 to 155 hairs/cm² over 16 weeks versus 104 to 129 with minoxidil alone (Yu et al., 2020); a network meta-analysis (pooled comparison of many treatments across trials) estimated +35 hairs/cm² for PRP plus bFGF plus minoxidil over minoxidil alone (Xia et al., 2025).

Faster healing of scalp and skin wounds ⭕️ Not Central to Hair Regrowth

Topical bFGF speeds skin-wound closure, which bears on recovery after microneedling, hair transplant surgery, or scalp injury rather than on regrowth itself. A 600-patient placebo-controlled RCT in second-degree burns (Fu et al., 1998) and a controlled burn study (Akita et al., 2008) showed faster healing and softer scars. The Fu trial used bovine bFGF, which differs from human bFGF at two amino-acid positions.

Magnitude: Superficial burns healed in 9.9 versus 12.4 days and deep second-degree burns in 17.0 versus 21.2 days with bFGF versus placebo (Fu et al., 1998).

Medium 🟩 🟩

Better graft survival after hair transplantation

In one RCT of 60 patients with moderate-to-severe AGA, holding harvested follicles in recombinant bovine bFGF solution during surgery and applying bFGF gel for three weeks afterward improved graft survival and reduced early shedding versus saline storage (Lei et al., 2025). Outcome assessors were blinded, but the product was bovine rather than human-sequence bFGF, so transfer to sh-Polypeptide-1 is inferred.

Magnitude: 12-month graft survival 91.1% versus 81.0%; postoperative hair-loss rate 11.6% versus 22.7%; complications 20.0% versus 85.3% (Lei et al., 2025).

Low 🟩

Thicker hair shafts ⚠️ Conflicted

In an uncontrolled study, 12 adults applying FGF-2 in a nanoparticle carrier for six months grew thicker hairs (Takabayashi et al., 2016). In an RCT, microneedle-delivered bFGF alone did not thicken hair, whereas minoxidil did (Yu et al., 2020). Net reading: a thickening effect of bFGF itself is unproven.

Magnitude: Mean hair diameter rose from 0.0290 to 0.0324 mm (about 12%) and the share of terminal (thick, pigmented) hairs from 21.5% to 26.4% in the uncontrolled study (Takabayashi et al., 2016).

Speculative 🟨

Earlier and longer hair-growth phase ⚠️ Conflicted

Topical FGF-2 started and prolonged anagen in mice (Lin et al., 2015), whereas injected bFGF delayed newborn mouse follicles (du Cros, 1993). Animal data only. Net reading: direction depends on dose and timing.

Preserved hair-inducing capacity of dermal papilla cells

In cell culture, FGF2 keeps dermal papilla cells dividing and, combined with platelet-derived growth factor, preserves their ability to form new follicles (Kiso et al., 2015). Basis is laboratory-only; no human outcome data exist.

Benefit-Modifying Factors

  • Genetic background: Variants in the androgen receptor gene (encoding the receptor for male hormones) set the pace of AGA and may limit how far any add-on offsets hormone-driven follicle shrinkage. No gene variant is known to alter bFGF response or breakdown.
  • Baseline biomarkers: Low ferritin (iron stores), thyroid imbalance, or low vitamin D cause shedding that bFGF does not correct; addressing these lets any growth-factor effect show and prevents misattributing results.
  • Sex: Most bFGF hair trials enrolled men; one PRP-plus-bFGF trial included 33 women among 80 participants (Qu et al., 2023). Female pattern hair loss, driven partly by different hormonal factors, lacks enough data for a separate judgment.
  • Pre-existing conditions: Trials enrolled mainly AGA; one observational transplant study included scarring alopecia (follicles replaced by scar tissue) (Yang et al., 2021), while alopecia areata (immune-driven patchy loss) went unstudied. Diabetes and smoking impair skin blood flow and may blunt growth-factor responses.
  • Age: Participants were mostly 21–55 years old. Long-standing bald areas in older adults hold fewer living follicles to respond; benefit was reported in earlier-stage thinning (Norwood-Hamilton II–IV, a standard male balding scale) (Liu et al., 2022).
  • Delivery method: Clinical benefits came with microneedling, injection, or protective carriers. Plain leave-on serums face the skin’s size barrier for large proteins and have no controlled hair data.

Potential Risks & Side Effects

High 🟥 🟥 🟥

No risk reaches High: controlled trials document no adverse event attributable to bFGF itself above its control arm, and the local reactions recorded come from a single trial of the needling procedure (Yu et al., 2020).

Medium 🟥 🟥

Transient scalp redness, itching, and procedure pain

Redness, itching, stinging, or pain occur mainly when bFGF is delivered by microneedling or injection. In one RCT of 40 men, 3 participants had mild erythema (skin redness) that cleared within 24 hours, and needle pain was well tolerated (Yu et al., 2020); adding topical bFGF to minoxidil did not raise adverse-reaction rates (Liu et al., 2022). Trafermin drug summaries list transient local redness and itching. Needling also carries small infection and bruising risks.

Magnitude: Mild erythema in 7.5% (3 of 40) of participants, resolving within 24 hours, with no serious adverse events (Yu et al., 2020).

Low 🟥

Blood-pressure drop with systemic exposure

Recombinant bFGF administered intravenously or intra-arterially lowered blood pressure in heart-disease and stroke trials (Bush et al., 2001, manufacturer-authored; Bogousslavsky et al., 2002). Scalp application produces negligible blood levels, so this evidence is indirect for topical use.

Magnitude: A 24-hour intravenous infusion of 5–10 mg trafermin lowered systolic (upper-number) blood pressure by 19–22 mm Hg versus 8 mm Hg with placebo (Bogousslavsky et al., 2002); scalp doses are thousands of times smaller.

Speculative 🟨

Growth stimulation of existing skin cancers

Melanoma cells produce bFGF as a self-sustaining growth signal (Halaban et al., 1988), and bFGF drives tumor blood-vessel growth. Basis is mechanistic; no cancer has been linked to topical bFGF.

Allergic sensitization to the recombinant protein

Recombinant proteins and residual E. coli components could provoke allergy, and trafermin lists hypersensitivity as a contraindication. Basis is mechanistic and label-based; no allergic reactions were reported in the scalp trials reviewed.

Risk-Modifying Factors

  • Genetic polymorphisms: No known variants alter bFGF handling. Inherited melanoma risk, such as CDKN2A mutations (a gene that normally restrains cell division), heightens the theoretical concern about applying a melanoma growth signal to sun-exposed scalp.
  • Baseline biomarkers: Low platelet count or prolonged clotting times raise bleeding and bruising with microneedling or PRP-based delivery; no blood marker predicts reactions to bFGF itself.
  • Sex: No sex differences in adverse events were reported. Pregnancy and breastfeeding lack any safety data for topical bFGF.
  • Pre-existing conditions: Scalp psoriasis, eczema, active infection, or prior scalp skin cancer increase irritation, infection, or theoretical tumor concerns; people prone to keloids (overgrown raised scars) face scarring risk from needling.
  • Age: Older adults have thinner, more sun-damaged scalps with more actinic keratoses (rough precancerous patches) and slower wound healing, raising the value of skin checks and gentler needling.

Key Interactions & Contraindications

Prescription drugs

  • FGFR inhibitors (cancer drugs that block FGF receptors: erdafitinib, pemigatinib, futibatinib): Caution. They block the receptors bFGF acts through, likely cancelling any hair effect, and users have active cancer. Mitigation: concurrent use only with the treating oncologist’s agreement.
  • Anticoagulants and antiplatelet drugs (blood thinners: warfarin, apixaban, clopidogrel): Monitor. No interaction with bFGF itself, but microneedling or injections cause more bleeding and bruising. Mitigation: shallow needles (0.5 mm or less); any pause only with the prescriber.
  • Topical minoxidil: Monitor; potentiating (additive). Combined use increased hair density in trials; minoxidil adds scalp irritation and, rarely, fluid retention. Mitigation: applying bFGF and minoxidil at different times of day if irritation occurs.
  • Retinoids (vitamin A–derived skin drugs: oral isotretinoin, topical tretinoin): Caution. Fragile, dry skin raises irritation and scarring risk with needling delivery. Mitigation: no microneedling within 6 months of isotretinoin; topical retinoids paused 3–5 days around sessions.
  • Immunosuppressants (drugs that dampen immunity: methotrexate, tacrolimus, prednisone): Monitor. Higher infection risk after needling and possibly slower wound repair. Mitigation: sterile single-use needles and no needling during flares.
  • Heparins (injectable blood thinners: heparin, enoxaparin, dalteparin): Monitor. Heparin binds bFGF and slowed its clearance after intravenous dosing, raising systemic exposure (Bush et al., 2001). Mitigation: relevant mainly to injected bFGF; intact-skin topical use yields negligible exposure.

Over-the-counter medications

  • Nonsteroidal anti-inflammatory drugs (NSAIDs, common pain relievers: aspirin, ibuprofen, naproxen): Monitor. More bruising and bleeding with microneedling. Mitigation: avoiding non-essential doses for 3 days before sessions.
  • Acidic or oxidizing scalp products (glycolic acid, salicylic acid, benzoyl peroxide): Caution. Low pH and oxidants can denature the protein, inactivating it, and add irritation. Mitigation: applying these at a different time of day from bFGF.

Supplements

  • Bleeding-prone supplements (fish oil, vitamin E, ginkgo): Monitor. Additive bleeding and bruising with needling. Mitigation: pausing 3–7 days before microneedling sessions.
  • Additive topical hair actives (caffeine, rosemary oil, copper tripeptide GHK-Cu, sh-Oligopeptide-1 epidermal growth factor): Monitor; potentiating in theory through overlapping follicle-stimulating mechanisms; no combined trials exist, and stacked products raise irritation. Mitigation: introducing one product at a time.

Other interventions

  • Platelet-rich plasma and microneedling: Monitor; potentiating. PRP plus bFGF outperformed PRP alone (Qu et al., 2023), and needling increases penetration; both add procedural bleeding and infection risk. Mitigation: sessions spaced 2–4 weeks apart, with bFGF applied immediately after needling under sterile conditions.

Populations who should avoid Sh-Polypeptide-1:

  • Active skin cancer on the scalp or face, or melanoma diagnosed within the past 5 years
  • People receiving active cancer treatment, including FGFR inhibitors
  • Pregnancy and breastfeeding (no safety data)
  • Known hypersensitivity to the product or any component
  • Active scalp infection, open wounds, or flaring psoriasis or eczema at the application site (for needling-assisted use)
  • Platelet count below 50,000/µL, or INR (international normalized ratio, a clotting-time measure) above 3.0 on anticoagulants (for needling- or injection-assisted use)
  • History of keloids (for needling-assisted use)

Risk Mitigation Strategies

  • Patch test before scalp use: Applying the product daily to a 2 cm area behind the ear for 3–5 days identifies allergic or irritant reactions before whole-scalp exposure.
  • Conservative microneedling parameters: Depths of 0.5–1.0 mm, sessions every 1–4 weeks, and sterile single-use tips limit the redness, pain, bleeding, and infection seen with needling delivery.
  • Scalp skin checks: A dermatologist’s scalp examination at baseline and every 12 months, with stopping and biopsy for any new or changing pigmented spot, addresses the theoretical tumor-growth concern.
  • No injection of cosmetic serums: Cosmetic sh-Polypeptide-1 products are not sterile injectables; injecting them risks infection and granulomas (inflammatory nodules). Injected protocols use clinic-prepared sterile products.
  • Topical-only amounts: Keeping to scalp doses of about 1–2 mL daily keeps blood levels negligible, avoiding the blood-pressure drops seen with intravenous doses.
  • Single-product introduction: Starting sh-Polypeptide-1 alone for 2 weeks before adding other scalp actives isolates the cause of any redness, itching, or allergic reaction.

Therapeutic Protocol

  • Clinical topical protocol (Shanghai trial): 3,500 international units (IU) of bFGF plus 1 mL 5% minoxidil applied twice daily for 6 months in men with early AGA (Liu et al., 2022).
  • Microneedle-assisted protocol (China Medical University, Shenyang): 1 mL bFGF solution sprayed on the balding area, then nano-microneedle passes once weekly for 16 weeks, with twice-daily 5% minoxidil (Yu et al., 2020).
  • PRP plus bFGF injections (Nanfang Hospital, Guangzhou): bFGF-enriched PRP injected into the skin, three sessions one month apart, alone (Qu et al., 2023) or with minoxidil (Wu et al., 2023); developed by the Hu Zhiqi and Miao Yong group.
  • Nanoparticle carrier approach (National Defense Medical College, Japan): 1 mL of 100 ng/mL FGF-2 bound to dalteparin/protamine nanoparticles massaged into the scalp twice daily for 6 months (Takabayashi et al., 2016).
  • Hair-transplant adjunct (Xijing Hospital, Xi’an): Grafts held in bFGF solution during surgery, then bFGF gel applied to the scalp for 3 weeks (Lei et al., 2025).
  • Cosmetic leave-on serums: Commercial sh-Polypeptide-1 scalp serums and ampoules, largely from Korean and other Asian brands, applied once or twice daily to a dry scalp; concentrations are usually undisclosed, and no controlled hair trial exists.
  • Time of day: No trial compared timings. Evening application after washing allows hours of undisturbed contact; with minoxidil, the two are often applied at opposite times to reduce irritation.
  • Half-life: Terminal half-life is about 7.6 hours after intravenous dosing; on skin, protease breakdown and heat instability limit activity, consistent with the daily or twice-daily topical schedules used.
  • Single or split dosing: Daily topical protocols split the dose twice daily; microneedle and injection protocols use single weekly or monthly sessions.
  • Genetic polymorphisms: No pharmacogenetic variants affect dosing. A strong family history of early balding signals androgen-driven loss, where bFGF has been studied only as an add-on to androgen-targeting or minoxidil therapy.
  • Sex: Trial doses were identical for men and women; women were mainly studied in PRP combinations. No pregnancy safety data exist.
  • Age: Participants were mostly 21–55 years old; one carrier-serum study enrolled ages 41–77 (Takabayashi et al., 2016). Older adults use the same doses in practice, with slower expected response and shallower needling depths given thinner skin.
  • Baseline biomarkers: Low ferritin, thyroid dysfunction, or low vitamin D cause shedding that blunts growth-factor response and confounds assessment; correcting them precedes a fair trial of bFGF.
  • Pre-existing conditions: Protocols were tested mainly in AGA, plus one transplant study in scarring alopecia (Yang et al., 2021); alopecia areata and active scalp dermatitis require diagnosis-specific treatment. Diabetes raises infection risk with needling.

Discontinuation & Cycling

  • Duration: bFGF is used as an ongoing add-on for as long as the effect is wanted; gains from growth-phase stimulation are expected to fade within months of stopping, though no study has followed people after stopping bFGF.
  • Withdrawal effects: None known for bFGF. The well-documented shedding after stopping comes from co-used minoxidil, not the growth factor.
  • Tapering: Not required pharmacologically. Clinics often move from weekly to monthly needling sessions for maintenance, based on practice rather than trials.
  • Cycling: No evidence shows that cycling preserves efficacy, and receptor desensitization has not been demonstrated in hair follicles.

Sourcing and Quality

  • Human versus bovine protein: sh-Polypeptide-1 is the human sequence made in E. coli. Much of the Chinese clinical data used recombinant bovine bFGF medicines (e.g., from Zhuhai Essex Bio-Pharmaceutical), which are distinct products.
  • Concentration disclosure: Cosmetic labels list sh-Polypeptide-1 without an amount, and many products contain trace levels. Brands stating IU or micrograms per mL allow comparison with trial doses in the thousands of IU.
  • Stability and packaging: The protein degrades with heat, time, and air exposure. Airless or single-dose ampoules, refrigeration, stabilizing carriers (liposomes, heparin-like polymers), and a stated use-by period after opening indicate quality.
  • Third-party testing: Independent assays of growth-factor activity in cosmetics are rarely published, and ConsumerLab does not test them. Supplier certificates of analysis showing bioactivity (a cell-proliferation assay) are the best available check.
  • Reputable sources: Trafermin (Fiblast Spray, Kaken Pharmaceutical) is a prescription product in Japan; recombinant bFGF medicines are licensed in China. Ingredient suppliers such as PNP Biopharm provide sh-Polypeptide-1 to cosmetic brands.
  • Sterility for needling: Cosmetic serums are not sterile injectables; products used with microneedling ideally come sterile and single-use.

Practical Considerations

  • Time to effect: Trials assessed benefit at 16 weeks (microneedle protocol; Yu et al., 2020) to 6 months (topical and PRP combinations); transplant graft survival was judged at 12 months (Lei et al., 2025).
  • Common pitfalls: Replacing proven drugs with a cosmetic serum; using products of unknown strength; storing ampoules warm; stopping before 3 months; and crediting co-therapy results to the growth factor.
  • Regulatory status: In the United States and European Union, sh-Polypeptide-1 is a cosmetic ingredient that cannot legally claim to treat hair loss; the U.S. Food and Drug Administration (FDA) has not approved it as a drug. Trafermin is a prescription medicine in Japan.
  • Cost and accessibility: Serums cost more than generic minoxidil, and clinic needling or PRP sessions add substantially. Insurers and national health systems generally exclude cosmetic hair-loss care, so payer incentives do not appear to shape this evidence.
  • Evidence transfer: Clinical results came from pharmaceutical bFGF with needling or injection; applying them to leave-on cosmetics is an extrapolation.

Interaction with Foundational Habits

  • Sleep: No direct interaction; no effect on sleep has been reported. Indirectly, short sleep raises stress hormones linked to telogen effluvium (stress-triggered shedding), which can mask growth-factor benefits. Evening application fits a bedtime routine and keeps the product on the scalp overnight.
  • Nutrition: Indirect. Follicles need adequate protein (about 1.2–1.6 g/kg/day for active adults), iron, zinc, and vitamin D to build hair; deficiencies blunt any signal bFGF provides. No foods interact with topical bFGF.
  • Exercise: Indirect, potentially supportive: exercise improves skin blood flow and insulin sensitivity, both relevant to follicle health. Heavy sweating and swimming pools are usually avoided for 24 hours after microneedling to reduce infection risk; applying bFGF after post-workout washing prevents dilution.
  • Stress management: Indirect. Chronic stress raises cortisol, pushing follicles into the resting phase and causing shedding that bFGF cannot offset. Meditation, breathwork, and consistent sleep support the same hair-cycle goals; no study has tested them alongside bFGF.

Monitoring Protocol & Defining Success

Baseline testing before starting establishes the cause of thinning and a measurable starting point: standardized scalp photographs, trichoscopy (magnified scalp imaging) of hair density and diameter at a marked site, and blood tests for ferritin, thyroid function, vitamin D, and zinc. A dermatologist’s scalp examination also documents any pigmented or precancerous lesions before a growth-promoting protein is applied.

Ongoing monitoring follows this cadence: photographs and trichoscopy at 3 months and 6 months, then every 6 months during use; a scalp skin check every 12 months; and repeat blood tests at 6–12 months if any baseline value was abnormal. Success is a rise in hair density or diameter above the individual’s own baseline at the same site, with stable or reduced shedding.

Biomarker Optimal Functional Range Why Measure It? Context/Notes
Hair density (trichoscopy) No established target; track change from own baseline (hairs/cm²) Primary efficacy readout Same marked site, trimmed hair, identical lighting; trials measured at baseline and 3–6 months
Hair shaft diameter (trichoscopy) No established target; track change from own baseline (µm) Detects thickening of shrunken hairs Measured at the same site as density; average at least 20 hairs
Ferritin 50–150 ng/mL Iron stores for hair growth Conventional range about 15–300 ng/mL (men) and 12–150 ng/mL (women); rises with inflammation, so pair with CRP (C-reactive protein, an inflammation marker); fasting not required
TSH 1.0–2.5 mIU/L Rules out thyroid-driven shedding TSH = thyroid-stimulating hormone; conventional range 0.4–4.5 mIU/L; morning draw; pair with free T4 (main circulating thyroid hormone)
25-hydroxyvitamin D 40–60 ng/mL Low levels are linked to hair loss Conventional sufficiency cutoff 30 ng/mL; lowest in late winter; no fasting needed
Serum zinc 90–120 µg/dL Deficiency causes shedding Conventional range about 60–120 µg/dL; fasting morning draw, as levels fall after meals

Qualitative markers:

  • Daily shedding in the shower or hairbrush
  • Scalp visibility through the part line or crown in consistent lighting
  • Hair volume, texture, and styling ease
  • Scalp comfort: itching, redness, or flaking after application
  • Self-rated satisfaction at 3 and 6 months

Emerging Research

  • No registered sh-Polypeptide-1 hair trials: A ClinicalTrials.gov search (September 2026) found no ongoing trial of sh-Polypeptide-1 or bFGF for hair regrowth, so no NCT ID exists; a placebo-controlled trial of a leave-on serum is the missing study most relevant to this audience.
  • Trafermin spray phase 3 trials: Two completed double-blind, placebo-controlled European trials of trafermin 0.01% spray (recombinant human bFGF) in diabetic foot ulcers enrolled 201 and 207 patients (NCT01217463; NCT01217476); their skin-safety data inform long-term topical exposure.
  • Fibroblast growth-factor mixture (HST 001): Histogen’s phase 1b, double-blind, placebo-controlled trial of injected HST 001, a mix of growth factors secreted by human skin fibroblasts, enrolled 36 men with pattern hair loss and measured target-area hair counts (NCT04435847).
  • Related growth-factor scalp essence: A 60-participant triple-blind, placebo-controlled trial tested a scalp essence containing insulin-like growth factor 1 (IGF-1) and keratinocyte growth factor (FGF7, a related family member) over 56 days (NCT06985121); the design could test sh-Polypeptide-1 serums.
  • Negative serum result: A keratinocyte growth factor hair serum failed to prevent chemotherapy-induced hair loss in 20 evaluable women (Mann et al., 2026; NCT04554732), tempering expectations for leave-on growth-factor serums.
  • Growth-factor injection meta-analysis: A 12-study meta-analysis of growth-factor injections prepared from patients’ own blood reported density gains but high risk of bias (design flaws that can skew results) and heterogeneity (disagreement between study results) above 90% (Alali et al., 2026), showing how weak designs can inflate apparent benefit.
  • Delivery research: A nanoparticle carrier protected FGF-2 from heat, improved rat skin penetration, and accompanied thicker human hair (Takabayashi et al., 2016); with the 500-dalton skin barrier (Bos & Meinardi, 2000), delivery is the decisive open question.

Conclusion

The cosmetic ingredient sh-Polypeptide-1 is a lab-made copy of human basic fibroblast growth factor, a protein that drives skin repair and new blood-vessel growth and, in animal and cell studies, helps restart the hair growth cycle.

For adults already treating thinning hair and open to clinic procedures, the most consistent human signal is modest extra hair density when the protein joins standard treatment and is delivered with fine needles or injections. It also speeds skin healing and may help transplanted hairs survive. Whether a plain leave-on serum works is unshown: the molecule is far too large to pass easily through intact skin, it breaks down quickly when warm, and no properly controlled study has tested a cosmetic product.

The human studies are small, short, and mostly from a few clinics in China, often using a cattle-derived version of the protein. Cosmetic claims come largely from suppliers and brands that profit from sales, one needling review came from a company selling hair-loss education, and early safety data came from a drug maker.

Reported side effects are mild and mostly caused by the needling itself. Drops in blood pressure have occurred only when the protein was administered intravenously. A theoretical concern remains because the same protein feeds some skin cancers, although no such case has been linked to scalp use.

Overall, the evidence points to a possible add-on role within a needle-based routine; the value of cosmetic serums alone is uncertain.

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