Acne scars are the result of the resolution of inflammatory lesions (papules, pustules, and nodules) and non-inflammatory lesions (comedones). They are classified as atrophic, hypertrophic, or keloid.

It is estimated that acne scars affect approximately 95% of individuals, significantly impacting their quality of life.^1-3

Atrophic scars result from collagen loss following inflammation of the pilosebaceous unit⁴ and, according to the classification by Jacob et al, are categorized into rolling, boxcar, and icepick scars.⁵

There are multiple therapeutic alternatives for improving the appearance of atrophic acne scars, including dermal fillers with hyaluronic acid (HA), poly-L-lactic acid, and calcium hydroxyapatite, as well as subcision, punch excision, chemical peels, microneedling, dermabrasion, and laser therapy, among others.⁶ Most treatments aim to break fibrotic bands beneath the scars and induce new collagen and connective tissue formation.

The combination of high- and low-molecular-weight ultrapure hyaluronic acid—known as hybrid cooperative complexes (HCCs)—has shown significant efficacy in activating fibroblasts and reducing the appearance of acne scars.⁷ These complexes create a space that prevents reattachment of fibrotic strands in the dermis and encourages new connective tissue formation above the product application, leading to aesthetic improvement.^8,9

During wound healing, the hygroscopic properties of hyaluronic acid support hydration and the structural integrity of the extracellular matrix, promoting cell migration, adhesion, and proliferation within granulation tissue.

HA also plays a role in reorganizing the extracellular matrix, collagen deposition, cytokine binding, and the recruitment of matrix metalloproteinases. Therefore, exogenous HA supplementation may benefit the management of aberrant scarring.

Profhilo is a high- and low-molecular-weight HA formulation based on HCCs, developed using patented NAHYCO Hybrid Technology. It is produced by thermally stabilizing a blend of high (1100-1400 kDa) and low (80-100 kDa) molecular weight HA, without the use of chemical crosslinkers like BDDE. The resulting hybrid complexes offer high HA concentration (64 mg/2 mL), low viscosity, high tissue diffusion, and minimal inflammatory response.

An essential feature of HCCs is their ability to integrate into tissue, due to their high cohesivity. They distribute uniformly across anatomical units and exhibit fluidity rather than elasticity—unlike crosslinked HA gels.⁹

The objective of this study was to retrospectively evaluate a pilot series of patients with atrophic acne scars treated identically with HCCs using a dual-plane injection technique in a Mexican population, in order to assess clinical evolution and improvement.

This was a retrospective, multicenter pilot study involving nine volunteer patients with post-acne scars graded ≥2 according to the Goodman and Baron qualitative global acne scar grading system (Table 1).

Treatments were administered at private dermatology clinics in Mexico by trained physicians, following a standardized technique.

The first treatment was administered at baseline (T0), the second after 30 days (T1), and the final evaluation was at 60 days (T2). Standardized photographs (frontal, oblique, and profile) were taken using a Canon EOS Rebel T7 digital camera at each time point (T0, T1, T2).

The principal investigator assessed scar severity using the Goodman and Baron scale at T0, T1, and T2. The final results were also evaluated by a blinded, independent physician using clinical images from T0 and T2.

Both treating physicians and patients rated aesthetic improvement at T2 using a 6-point Likert scale: -1: worsening of acne scars; 0: no change; 1: 1-25% improvement; 2: 25-50% improvement; 3: 50-75% improvement; 4: 75-99% improvement.

Patient satisfaction was measured at T2 using the 5-point Global Aesthetic Improvement Scale (GAIS): 1 = much improved; 2 = very improved; 3 = improved; 4 = no change; 5 = worse. Adverse events were documented at each visit (T0 and T2).

Inclusion criteria: adults >18 years with rolling, boxcar, or icepick facial scars; Goodman and Baron score ≥2; Fitzpatrick skin types III-IV.

Exclusion criteria: age <18, history of keloids, active inflammatory acne, scars outside the face, previous treatments (injectables, peels, lasers, biostimulators) within 6 months, immunosuppression, active infections (e.g., herpes), isotretinoin therapy, or facial plastic surgery within 12 months.

All patients signed informed consent and completed medical history forms. The study was conducted across multiple private clinics in Mexico by different physicians following standardized protocols.

Before treatment, the face was cleansed with dermo-cleansing foam, and topical anesthetic cream (5% lidocaine, EMLA^®; AstraZeneca^®) was applied 20 minutes before injection. Aseptic preparation was performed, and patients were placed in a 45° semi-Fowler position.

The injection protocol involved dividing the scarred area into 4x4 cm quadrants, injecting 0.01-0.2 mL of Profhilo^® per lesion, depending on severity, using a 29 Gx13mm needle into the deep dermis.

Then, a subdermal application was performed using a 23Gx50mm cannula with subcision and a linear retrograde technique, delivering 0.1-0.2 mL per vector. The same procedure was repeated at T1. After each session, patients were instructed to use only daily sunscreen.

Nine patients were recruited between March and November 2024, including five men and four women. The mean age was 35.3 years.

All patients entered the study with a Goodman and Baron score of 4 and completed it with an average score of 2.25, as evaluated by the principal investigator (Graphic 1).

At the end of treatment, all patients rated the outcome as positive, with improvement greater than 25%, and the majority (45%) rated their improvement as greater than 75% (Graphic 2).

At the end of the treatment, the attending physicians also rated the outcome as positive, with an improvement greater than 15%. In 22% of cases, the result was rated as greater than 75% (Graphic 3).

The GAIS scale for treatment satisfaction at the end of the study was rated by patients within the range of Much improved to Very much improved (Graphic 4).

A clinical photograph showing the before-and-after results of the treatment is presented in Photograph 1. No adverse events were reported.

The treatment of acne scars represents a clinical challenge due to the complex factors that contribute to their formation and persistence. In this study, a dual-plane injection technique was employed with Profhilo^®, a hyaluronic acid-based complex, yielding significant reductions in the severity of atrophic scars. The observed outcomes reflect the unique ability of HCCs to activate fibroblasts and stimulate collagen production, thereby promoting dermal regeneration and enhancing the overall appearance of scars.

Compared to other acne scar treatments—such as chemical peels, laser therapies, and other dermal fillers—, the HCC-based approach offers specific advantages:

• low viscosity,
• high tissue diffusion,
• and minimal inflammatory response.

The dual-plane technique effectively targets both the dermal surface and deeper layers, achieving better product integration and preventing the reattachment of scar fibers.

It is well established that HCCs of hyaluronic acid exhibit longer-lasting, fully reversible effects, with high biocompatibility and minimal immunogenicity.

Beyond their dermal effects, HCCs promote adipogenic differentiation and proliferation by upregulating adipogenic genes and associated proteins, leading to tissue bioremodeling across the skin layers. This mechanism is particularly relevant in atrophic acne scars, where subcutaneous fat loss and structural collapse contribute.

In contrast, linear and cross-linked HA formulations primarily exert a volumizing effect, without significantly affecting collagen- or adipocyte-related pathways. Therefore, the observed improvement in fat tissue renewal with HCCs may offer a novel approach to scar correction at deeper planes.

It is important to note that although the results of this study are promising, the relatively small sample size and the absence of a control group limit the generalizability of the findings. Future studies with a randomized, controlled design and larger sample sizes are needed to validate these results and explore long-term efficacy.

Lastly, the standardization of the application technique and the evaluation by an investigator independent from the treating physicians represent a strength of the study, providing reproducible results that can be applied in similar clinical settings.