A barrier that cannot be crossed

Cellulite is a morphologically complex condition rooted in the structural characteristics of subcutaneous adipose tissue in women: lobules of adipocytes oriented perpendicular to the skin surface and surrounded by vertical fibrous septa create the hallmark uneven relief. Its pathogenesis involves microcirculatory dysfunction, an inflammatory component, and extracellular matrix remodeling. Despite the wide range of available approaches — from mechanical techniques to energy-based technologies — none guarantees a lasting result in all patients, which sustains ongoing interest in new and combination treatment strategies [1].

Enzymes as a tool for targeting adipose tissue have long been used in medicine — most notably in injectable form for submental fat reduction. Topical lipolytic enzymes — lipase and collagenase — are appealing precisely because they are non-injectable: lipase catalyzes the hydrolysis of triglycerides, while collagenase breaks down the collagen fibers of the fibrous septa, which theoretically addresses key links in the pathogenesis of cellulite. However, realizing this potential is blocked by a fundamental barrier — the stratum corneum.

According to the 500 Da rule, only molecules with a molecular weight below ~500 Da can diffuse through intact skin. Enzymes are vastly larger and physically incapable of penetrating the subcutaneous tissue on their own [2]. This limitation has long prevented topical lipolytic agents from establishing a meaningful place in the evidence base for cellulite correction. The question was straightforward: how do you deliver the active compound where it is needed, without a needle?

RF as a "carrier": the scientific rationale for the combination

One possible answer is to use RF not only as a standalone therapeutic modality but also to modify the biophysical properties of tissue, thereby enhancing the permeability of topically applied compounds. Experimental data suggest that an alternating electric field at approximately 1 MHz — within the radiofrequency range — may increase the deformability of cell membranes, potentially facilitating the diffusion of compounds through tissue [3]. At the same time, the controlled hyperthermia generated by RF activates fibroblasts, triggers extracellular matrix remodeling, and may induce adipocyte apoptosis via calcium-dependent pathways.

The logic of the combined approach thus operates on two levels: RF acts directly on adipose tissue and connective structures, while the enzymes potentially augment and complement this effect — provided sufficient penetration occurs. It was precisely this hypothesis that a team of Spanish researchers set out to test in a pilot randomized study published in 2026 [1].

Study design

The study was designed as an exploratory randomized parallel-group trial. Twenty women with thigh cellulite graded I–IV on the Nürnberger–Müller scale were enrolled. Mean age was 51.5 ± 12.1 years in the monotherapy group and 44.3 ± 13.4 years in the combination group; baseline BMI did not differ significantly between groups. Participants were randomized 1:1: an RF monotherapy group (n = 10) and a combination therapy group — the same RF device plus topical enzymes (n = 10).

A multichannel RF device in a four-channel configuration was used: each channel consisted of an active–passive plate pair, with two pairs operating simultaneously on each side of the thigh. Each active plate had a surface area of 200 cm². The protocol comprised two sequential phases. In the first phase (20 minutes), high-power RF energy was delivered via active plates positioned over the cellulite zone. In the second phase (10 minutes), RF was applied in two modes — capacitive (energy concentrated predominantly in the superficial tissue layers) and resistive (penetrating deeper, reaching the musculofascial structures) [5] — using a cross-fire configuration: transmitting plates were placed on the soles of the feet and receiving plates on the lower dorsal region, directing the energy flow upward through the tissue while simultaneously performing lymphatic drainage. Total session duration was approximately 30 minutes. The course consisted of 10 sessions administered twice weekly over 5 weeks. In the monotherapy group, a neutral hydrating serum was applied to facilitate plate gliding.

The enzyme formulation was prepared ex tempore: lyophilized lipase (3,700 U/vial) and collagenase (850 U/vial) were reconstituted in 10 mL of physiological saline. 2.5 mL of the resulting solution was applied to each trochanteric area during the active plate phase, and an additional 2.5 mL during the cross-fire phase [4]. Enzyme application thus occurred in real time during RF delivery — not before or after.

Efficacy was assessed across three parameters: thigh circumference (anthropometry); subcutaneous tissue thickness by ultrasound (5–18 MHz linear probe; three measurements per site, averaged); and photographic evaluation using the Cohen et al. cellulite severity scale under standardized imaging conditions. Statistical analysis included repeated-measures ANOVA for within-group dynamics and one-way ANOVA for between-group comparisons; significance threshold was set at α = 0.05.

Results

Both groups showed improvement across all assessed parameters; however, between-group differences were statistically significant. Mean thigh circumference decreased by 6.1 cm in the monotherapy group and by 14.8 cm in the combination group (p = 0.020). Ultrasound-measured subcutaneous tissue thickness decreased by 8.77 mm and 14.64 mm, respectively (p = 0.019). Photographic evaluation likewise recorded more pronounced improvements in participants who received enzymes alongside RF.

Safety and adverse events

No serious adverse events were recorded. Participants reported a mild, subjectively tolerable sensation of warmth during sessions, as well as transient erythema that resolved spontaneously within 20 minutes after each session. The publication contains no reports of allergic reactions or other complications related to the enzyme formulation.

Limitations

The authors openly enumerate the limitations of their work. The primary concern is the small sample size: 10 participants per group does not allow for broad generalizations, and the study was not adequately powered from the outset. A further issue is baseline imbalance: Grade IV cellulite was present exclusively in the combination group, which may have influenced the observed outcomes; no adjustments for BMI or baseline cellulite grade were incorporated into the analysis. Participant blinding was not performed, and no long-term follow-up was planned. These factors mean that the results should be regarded as preliminary and require confirmation in larger, adequately powered randomized trials.

Practical implications and conclusions

Despite its methodological limitations, this study addresses a practically relevant question: how to improve the efficacy of RF-based cellulite treatment without injectable interventions. Both components of the combination already have a well-characterized safety profile — RF devices are widely used in aesthetic medicine, and topical enzymes produce no systemic effects. The potential synergistic interaction — simultaneous thermal action of RF and enzymatic lipolysis with degradation of fibrous septa — appears biologically plausible.

A key mechanistic question remains open: to what extent does RF genuinely enhance transdermal enzyme delivery, versus the two modalities working independently and simply adding their effects together? Answering this requires purpose-designed studies with pharmacokinetic data. For now, the takeaway from Rodriguez Lastra and Kouser's pilot work is this: adding topical enzymes to a standardized multichannel RF protocol is associated with statistically significantly greater reductions in thigh circumference and subcutaneous tissue thickness compared with RF monotherapy, with good tolerability and minimal reversible adverse events. The findings are preliminary and cannot support definitive clinical conclusions — larger, adequately designed trials that control for key confounders and include long-term follow-up are needed. Nevertheless, the direction is clear: using RF devices as "carriers" for topical enzymatic agents is a promising avenue for improving the efficacy of non-invasive cellulite correction.

References

1. Rodriguez Lastra J., Kouser S. Topical lipolytic enzymes combined with a multichannel energy-based device for cellulite treatment. Health Sci Rep 2026; 9: e72583.
2. Bos J.D., Meinardi M.H.M. The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Exp Dermatol 2000; 9(3): 165–169.
3. Dastani K., Moghimi Zand M., Kavand H. et al. Effect of input voltage frequency on the distribution of electrical stresses on the cell surface based on single-cell dielectrophoresis analysis. Sci Rep 2020; 10: 68.
4. Mecott-Rivera G.A., Canseco-Cavazos J.C., Richer-Peña J.A. et al. Effect of exogenous lipase on subcutaneous adipose tissue in a porcine animal model. J Cosmet Dermatol. 2022; 21(10): 4990–4998.
5. Belenky I., Margulis A., Elman M. et al. Exploring channeling optimized radiofrequency energy: a review of radiofrequency history and applications in esthetic fields. Adv Ther 2012; 29(3): 249–266.