Standardized in vitro analysis of the degradability of hyaluronic acid fillers by hyaluronidase

Comparison of Hyaluronidase-Mediated Degradation Kinetics of Commercially Available Hyaluronic Acid Fillers In Vitro

BACKGROUND

The ability to degrade hyaluronic acid (HA)-based fillers with hyaluronidase allows for better management of adverse effects and reversal of suboptimal treatment outcomes.

OBJECTIVES

The aim of this study was to compare the enzymatic degradation kinetics of 16 commercially available HA-based fillers, representing 6 manufacturing technologies.

METHODS

In this nonclinical study, a recently developed in vitro multidose hyaluronidase administration protocol was used to induce degradation of HA-based fillers, enabling real-time evaluation of viscoelastic properties under near-static conditions. Each filler was exposed to repeated doses of hyaluronidase at intervals of 5 minutes to reach the degradation threshold of G' ≤ 30 Pa.

RESULTS

Noticeable differences in degradation characteristics were observed based on the design and technology of different filler classes. Vycross fillers were the most difficult to degrade and the Cohesive Polydensified Matrix filler was the least difficult to degrade. Preserved Network Technology products demonstrated proportional increases in gel degradation time and enzyme volume required for degradation across the individual resilient hyaluronic acid (RHA) products and indication categories. No obvious relationship was observed between gel degradation characteristics and the individual parameters of HA concentration, HA chain length, or the degree of modification of each filler when analyzed separately; however, a general correlation was identified with certain physicochemical properties.

CONCLUSIONS

Manufacturing technology was the most important factor influencing the reversibility of an HA product. An understanding of the differential degradation profiles of commercially available fillers will allow clinicians to select products that offer a higher margin of safety due to their preferential reversibility.

LEVEL OF EVIDENCE: 4

High-dose pulsed hyaluronidase for managing nasal skin necrosis following hyaluronic acid treatment in nasolabial folds: A case report

The growing popularity of soft tissue filler injections has brought attention to the associated risks, particularly vascular complications, and their treatments. This case report focuses on a 34-year-old female who developed nasal skin necrosis following hyaluronic acid (HA) filler injection for nasolabial fold (NLF) enhancement. Despite the careful procedure, complications emerged rapidly, emphasizing the critical importance of prompt diagnosis and intervention. A total of 10,000 turbidity reducing units (TRU) of hyaluronidase (HSE) were administered in a high-dose pulsed manner, alongside hyperbaric oxygen therapy. The patient experienced a gradual but significant improvement over 60 days. This case underscores the need for constant vigilance in aesthetic medicine and the potential consequences of even minute HA amounts, exceeding zero, in causing severe vascular events.

Optimizing enzyme-responsive polymersomes for protein-based therapies

Aims: Stimuli-responsive polymersomes are promising tools for protein-based therapies, but require deeper understanding and optimization of their pathology-responsive behavior. Materials & methods: Hyaluronic acid (HA)-poly(b-lactic acid) (PLA) polymersomes self-assembled from block copolymers of varying molecular weights of HA were compared for their physical properties, degradation and intracellular behavior. Results: Major results showed increasing enzyme-responsivity associated with decreasing molecular weight. The major formulation differences were as follows: the HA(5 kDa)-PLA formulation exhibited the most pronounced release of encapsulated proteins, while the HA(7 kDa)-PLA formulation showed the most different release behavior from neutral. Conclusion: We have discovered design rules for HA-PLA polymersomes for protein delivery, with lower molecular weight leading to higher encapsulation efficiency, greater release and greater intracellular uptake.

A Safe-by-Design Approach for the Synthesis of a Novel Cross-Linked Hyaluronic Acid with Improved Biological and Physical Properties

Hyaluronic acid (HA) is a polymer with unique biological properties that has gained in interest over the years, with applications in pharmaceutical, cosmetic, and biomedical fields; however, its widespread use has been limited by its short half-life. Therefore, a new cross-linked hyaluronic acid was designed and characterized using a natural and safe cross-linking agent, such as arginine methyl ester, which provided improved resistance to enzymatic action, as compared to the corresponding linear polymer. The antibacterial profile of the new derivative was shown to be effective against S. aureus and P. acnes, making it a promising candidate for use in cosmetic formulations and skin applications. Its effect on S. pneumoniae, combined with its excellent tolerability profile on lung cells, also makes this new product suitable for applications involving the respiratory tract.

Time- and Dose-Dependent Effects of Hyaluronidase on the Degradation of Different Hyaluronan-Based Fillers In Vitro

BACKGROUND

Hyaluronidase (HYAL) is regarded as the standard for the management of complications associated with hyaluronan (HA)-based fillers. Therefore, the understanding of interactions of HA fillers and HYAL is essential.

METHODS

Nine different commercially available HA fillers (Belotero, Juvéderm, and Restylane) with varying degrees of cross-linking were used for the analysis. Fluorescently dyed HA fillers were individually incubated with varying doses of HYAL [bovine HYAL (Hylase "Dessau"; Riemser Pharma, Germany); 5, 10, and 20 U/mL] or sodium chloride and monitored by time-lapse microscopy. HA filler degradation was assessed as a decrease in fluorescence intensity of HA filler plus HYAL compared to HA filler plus control, quantified by computerized image analysis.

RESULTS

HA fillers show significant differences in their reaction to HYAL. Levels of degradation of HA fillers are positively correlated with increasing concentrations of HYAL. At the highest concentration of HYAL (20 U/mL), all fillers except one (Belotero Volume) reached a significant level of degradation at 5 to 9 hours.

CONCLUSIONS

In this study, the authors show that most HA fillers can be dissolved by HYAL in a dose- and time-dependent manner. Of note, the fillers' technology and degree of cross-linking seem to exert stronger effects on the degradability by HYAL as compared to the concentration of HA.

CLINICAL RELEVANCE STATEMENT

The authors' in vitro analyses support clinical recommendations stating that in the case of a vascular filler incident, HYAL should be applied early and at significant doses ("Time is skin!").

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Multidose Hyaluronidase Administration as an Optimal Procedure to Degrade Resilient Hyaluronic Acid Soft Tissue Fillers

Minimally invasive hyaluronan (HA) tissue fillers are routinely employed to provide tissue projection and correct age-related skin depressions. HA fillers can advantageously be degraded by hyaluronidase (HAase) administration in case of adverse events. However, clear guidelines regarding the optimal dosage and mode of administration of HAase are missing, leaving a scientific gap for practitioners in their daily practice. In this study, we implemented a novel rheological procedure to rationally evaluate soft tissue filler degradability and optimize their degradation kinetics. TEOSYAL RHA^® filler degradation kinetics in contact with HAase was monitored in real-time by rheological time sweeps. Gels were shown to degrade as a function of enzymatic activity, HA concentration, and BDDE content, with a concomitant loss of their viscoelastic properties. We further demonstrated that repeated administration of small HAase doses improved HA degradation kinetics over large single doses. Mathematical analyses were developed to evaluate the degradation potential of an enzyme. Finally, we tuned the optimal time between injections and number of enzymatic units, maximizing degradation kinetics. In this study, we have established a scientific rationale for the degradation of HA fillers by multidose HAase administration that could serve as a basis for future clinical management of adverse events.

Review of Delayed Reactions to 15 Hyaluronic Acid Fillers

BACKGROUND

Delayed-onset reactions are increasingly relevant given the growing use of hyaluronic acid dermal fillers. There is poor understanding of the phenomenon's etiology and incidence.

OBJECTIVE

To highlight differences between the dermal filler products with an emphasis on delayed-onset reaction incidence, pathogenesis, prevention, and treatment.

METHODS

A literature review was performed for delayed-onset reactions following hyaluronic acid dermal filler injection using PubMeb and Embase. Articles were included based on relevance, quality, and the predetermined definition of "delayed-onset reaction" (>30 days post injection). A total of 28 studies were included in the data analysis.

RESULTS

A total of 13,136 subjects from 28 studies treated with 15 filler types were included in the analysis. VYC-15L dermal filler injections carried the highest risk of delayed reaction with a mean incidence of 3.83% ( n = 46/1,202), followed by VYC-20L (0.92%) and VYC-17.5L (0.88%). The mean incidence of delayed reactions among all filler types was 1.13%.

CONCLUSION

Incidence of delayed reaction to hyaluronic fillers ranges from 0% to 3.83% (mean = 1.13%) and varies by filler type. The exact etiology of these delayed reactions remains disputed. Future studies should report reaction description, precise timeline, and posttreatment immunologic history to better delineate the incidence of delayed-onset hypersensitivity reactions.

Hyaluronan Hydrogels: Rheology and Stability in Relation to the Type/Level of Biopolymer Chemical Modification

BDDE (1,4-butanediol-diglycidylether)-crosslinked hyaluronan (HA) hydrogels are widely used for dermo-aesthetic purposes. The rheology and stability of the gels under physiological conditions greatly affect their clinical indications and outcomes. To date, no studies investigating how these features are related to the chemistry of the polymeric network have been reported. Here, four available HA-BDDE hydrogels were studied to determine how and to what extent their rheology and stability with respect to enzymatic hydrolysis relate to the type and degree of HA structural modification. ¹H-/¹³C-NMR analyses were associated for the quantification of the “true” HA chemical derivatization level, discriminating between HA that was effectively crosslinked by BDDE, and branched HA with BDDE that was anchored on one side. The rheology was measured conventionally and during hydration in a physiological medium. Sensitivity to bovine testicular hyaluronidase was quantified. The correlation between NMR data and gel rheology/stability was evaluated. The study indicated that (1) the gels greatly differed in the amounts of branched, crosslinked, and overall modified HA, with most of the HA being branched; (2) unexpectedly, the conventionally measured rheological properties did not correlate with the chemical data; (3) the gels’ ranking in terms of rheology was greatly affected by hydration; (4) the rheology of the hydrated gels was quantitatively correlated with the amount of crosslinked HA, whereas the correlations with the total HA modification level and with the degree of branched HA were less significant; (5) increasing HA derivatization/crosslinking over 9/3 mol% did not enhance the stability with respect to hyaluronidases. These results broaden our knowledge of these gels and provide valuable information for improving their design and characterization.

A Comprehensive Review of Non-Energy-Based Treatments for Atrophic Acne Scarring

Scarring is a dire consequence of acne vulgaris. Particularly, atrophic acne scarring is highly prevalent among young adults, and its physical and psychological effects can persist throughout their lives if left untreated. This literature review will analyze various non-energy-based approaches to treating atrophic acne scarring, emphasizing recent advances within the last 5 to 10 years. To accomplish this, we performed a PubMed search for various acne scar treatments such as chemical peels, dermabrasion, microdermabrasion, subcision, microneedling, punch techniques, dermal fillers, and thread lifting. Our findings and analysis show that there is no panacean solution to treating atrophic acne scars, which explains the evolving trend towards developing unique combinatorial treatments. Although a fair comparison of each treatment approach is difficult to achieve due to the studies’ varying sample sizes, strength of evidence, treatment execution, etc, there still remains a level of consensus on what treatments are well suited for particular scar types.

Hyaluronidases and hyaluronate lyases: From humans to bacteriophages

Hyaluronan is a non-sulfated negatively-charged linear polymer distributed in most parts of the human body, where it is located around cells in the extracellular matrix of connective tissues and plays an essential role in the organization of tissue architecture. Moreover, hyaluronan is involved in many biological processes and used in many clinical, cosmetic, pharmaceutic, and biotechnological applications worldwide. As interest in hyaluronan applications increases, so does interest in hyaluronidases and hyaluronate lyases, as these enzymes play a major part in hyaluronan degradation. Many hyaluronidases and hyaluronate lyases produced by eukaryotic cells, bacteria, and bacteriophages have so far been described and annotated, and their ability to cleave hyaluronan has been experimentally proven. These enzymes belong to several carbohydrate-active enzyme families, share very low sequence identity, and differ in their cleaving mechanisms and in their structural and functional properties. This review presents a summary of annotated and characterized hyaluronidases and hyaluronate lyases isolated from different sources belonging to distinct protein families, with a main focus on the binding and catalytic residues of the discussed enzymes in the context of their biochemical properties. In addition, the application potential of individual groups of hyaluronidases and hyaluronate lyases is evaluated.

The 10-Point Plan 2021: Updated Concepts for Improved Procedural Safety During Facial Filler Treatments

Dermal filler treatments require constant reassessment for improving and safeguarding the rapidly evolving aesthetic field. Suboptimal injection technique, patient selection and product knowledge have touted a concerning increase in filler complications, with new challenges such as the COVID-19 pandemic leading to new paradigms in the understanding, prevention, diagnosis and treatment of complications. The updated 10-point plan has been developed to curtail complications through consideration of causative factors, categorized as patient, product, and procedure-related. Patient-related factors include a preprocedural consultation with careful elucidation of skin conditions (acne, rosacea, dermatitis), systemic disease (allergies, autoimmune disease, underlying bacterial and viral disease (herpes simplex virus, COVID-19 infection), medications (antineoplastic drugs, recreational drugs) and previous cosmetic procedures (including fillers and energy-based devices). Patient assessment should include standardized photography and also evaluate the role of social media, ethnicity, gender, generational, and LGBTQ+ needs. Specified informed consent for both adverse events and their treatment is essential due to the increase in vascular complications, including the risk of blindness. Product-related factors include the powerful advantage of reversibility when using hyaluronic acid (HA) products. Product characteristics such as molecular weight and filler degradation should be understood. Product layering over late or minimally degradable fillers is still inadvisable due to the initial filler being teased into reactivity. Procedural factors such as consistent photographic documentation, procedural planning, aseptic non-touch technique (ANTT), knowledge of topographical anatomy and angiosomes, and technical dexterity including pinch anatomy and needle skills are of pivotal importance. The final section is dedicated to algorithms and checklists for managing and treating complications such as allergic hypersensitivity reactions, vascular events, infection, edema and late-onset adverse events (LOAEs). The updated 10-point plan is a methodical strategy aimed at further minimising the risk of dermal filler complications.

Guideline for the Management of Hyaluronic Acid Filler-induced Vascular Occlusion

Vascular occlusions can occur with injection of dermal fillers causing devastating outcomes for the patient. The occurrence, and subsequent management, of these negative outcomes is a source of significant stress to the aesthetic clinician. Complications management is an essential component of clinical practice and professionals must develop competence and confidence in the identification and effective treatment of a vascular occlusion. The relatively rare occurrence of a vascular occlusion mandates that learning must be largely through the study of theory in addition to the sharing of learning experiences within a collaborative clinical community. The delivery of optimal care begins with an understanding of the underlying pathophysiology and the ability to assess and elicit clinical signs. Establishing a clinical diagnosis, targeted therapy can commence in a timely fashion. This paper provides guidance on how to identify and manage a vascular occlusion caused by cross-linked hyaluronic acid. It provides a detailed description of the pathological process of tissue ischemia, and introduces identifiable stages which will help to determine the extent of ischemia and the time frame since ischemic onset. The stages are particularly important as they highlight when wound support may be needed.

Comparative Analysis of Hyaluronidase-Mediated Degradation Among Seven Hyaluronic Acid Fillers in Hairless Mice

Purpose

Hyaluronic acid (HA) is the most common injectable dermal filler used for soft-tissue augmentation, and can be removed non-surgically by directly injecting hyaluronidase. In this study, the hyaluronidase-mediated degradation of different types of HA fillers implanted subcutaneously at the back of hairless mice having filler residence time of four days or three months were compared.

Methods

Two sites at the back of female hairless mice were subcutaneously implanted with 0.1-mL of one of the seven HA fillers (NLL, NL, NDL, NVL, and ND, JUV_X+, and RES_LYFT) and injected with 30 IU or 60 IU hyaluronidase per 0.1-mL filler after reaching a filler residence time of 4 or 91 days, respectively. Filler bolus projection was measured using three-dimensional optical imaging over a 72 h period, and the implantation sites were histologically examined 2 weeks after hyaluronidase injection.

Results

Following hyaluronidase injection, all seven HA fillers showed a rapid decrease of filler volume within 24 h, and complete degradation was confirmed by histological examination after 2 weeks. There was no significant difference in filler volume reduction rate among the seven HA fillers, and no evidence of macroscopic or microscopic adverse effects were observed at the implantation sites.

Conclusion

All seven HA fillers show comparable susceptibility to hyaluronidase-mediated degradation. HA fillers with prolonged filler residence time may require a higher dose of hyaluronidase to achieve efficient degradation owing to tissue integration.

Prevention and Management of Filler Induced Iatrogenic Stroke of the Eye

In the past few decades, minimally-invasive esthetic treatments and the use of injectable Hyaluronic Acid Gels and other filling agents to treat facial esthetics have increased dramatically. Although extremely rare, a filler can cause ocular and orbital ischemia by retrograde flow from the ophthalmic artery when injected in any of the anastomosis of the face. Once filler reaches the central retinal artery, blindness is inevitable, and no treatment is effective. While the risk of blindness happening with any filler injection is rare, the life-altering irreversible consequence of a procedure that was anticipated to be simple and beautifying is a reality that each injector must be prepared for with every injection. The parameters associated with an iatrogenic stroke of the eye are the site of injection, the injection technique, patient characteristics, and the material injected. Understanding the interplay of each of these variables might help us reduce the possibility of blindness during the injection of a soft-tissue cosmetic filler. Here, we explore the causes of Hyaluronic Acid Gels Filler embolic phenomena, review the natural course of the process, and discuss appropriate immediate interventions. We also (1) propose an education plan for injectors and describe how to carry out a focused ophthalmologic examination and procedural activities for a referral to an ophthalmologist, (2) outline steps to prevent emboli during filler injection, and (3) how to manage and support a patient with a sudden loss of vision during or immediately after a Hyaluronic Acid Gels filler treatment.

Prospective in vivo evaluation of three different hyaluronic acid gels to varying doses of hyaluronidase with long-term follow-up

PURPOSE

Several injectable hyaluronic acid dermal fillers exist in the market, each with different rheologic and cross-linking properties. Their reversibility is useful for managing complications. We sought to determine the response of three different hyaluronic acid gels to varying doses of hyaluronidase.

METHODS

Each of 18 arms of nine subjects were prospectively randomized to receive intradermal injections of hyaluronic acid gel (Restylane-L, Juvéderm Ultra, Juvéderm Voluma). Seven sites on each arm were randomized to receive 0.2 mL of hyaluronic acid gel in anticipation of dissolution 1 week later with varying doses of hyaluronidase (Hylenex), 2.5, 5, 10, or 20 units or to be a control site. The outcome measures of diameter, elevation, and firmness were measured pre-injection and at varying time points to beyond 4 years. Subjects, graders, and injectors were masked.

RESULTS

The most dramatic changes for all fillers occurred starting at the 30-min time point through 3 h time point, with continued gradual degradation through week 2. A mild dose response was found for Juvéderm and Restylane; however, a clear dose response was seen from 2.5 to 10 units for Voluma, with 2.5 units showing features more like those of saline only or no hyaluronidase control. One Restylane arm had controls lasting four years.

CONCLUSIONS

All fillers had a dose response, with Voluma exhibiting it most clearly. Voluma required higher doses of hyaluronidase for dissolution, i.e., more than 20 units per 0.2 mL of filler. Restylane appeared to respond most readily to hyaluronidase, at the dose of even 2.5 units, but it also was fastest to dissolve on its own.

Evaluation of the Rheologic and Physicochemical Properties of a Novel Hyaluronic Acid Filler Range with eXcellent Three-Dimensional Reticulation (XTR™) Technology

Soft-tissue fillers made of hyaluronic acid and combined with lidocaine have recently become a popular tool in aesthetic medicine. Several manufacturers have developed their own proprietary formulae with varying manufacturing tools, concentrations, crosslinked three-dimensional network structures, pore size distributions of the fibrous networks, as well as cohesivity levels and rheological properties, lending fillers and filler ranges their unique properties and degradability profiles. One such range of hyaluronic acid fillers manufactured using the novel eXcellent three-dimensional reticulation (XTR™) technology was evaluated in comparison with other HA fillers and filler ranges by an independent research laboratory. Fillers manufactured with the XTR™ technology were shown to have characteristic rheological, crosslinking and biophysical factors that support the suitability of this filler range for certain patient profiles.

The "ART" of facial filler injections: Avoid, recognize, and treat hyaluronic acid-induced complications

BACKGROUND

Hyaluronic acid (HA) fillers are frequently used for cosmetic purposes as volumizers or as wrinkle fillers. One of the major advantages of hyaluronic acid use is the possibility to neutralize it by using hyaluronidase should complications occur.

PATIENT

A case of a 21-year-old female patient is presented, in whom a hyaluronic acid injection-induced vascular occlusion was seen four days after the initial injection, with increasing pain and severe signs of ischemia.

METHOD

Treatment consisted of an immediate hyaluronidase injection, supplemented with administration of acetylsalicylic acid, piracetam, low molecular weight heparin (LMWH), corticosteroids, analgesics, prophylactic antibiotics, application of topical nitroglycerin and warmth, smoking cessation, and hyperbaric oxygen therapy.

RESULTS

The initial progress and evolution of the deformity with possible therapeutic options are being discussed.

CONCLUSION

The "ART" (avoid, recognize, and treat) in handling filler complications is presented, as a new universal guideline for clinical aesthetic practitioners and injectors.

Cross-linked hyaluronic acid filler hydrolysis with hyaluronidase: Different settings to reproduce different clinical scenarios

Skin necrosis is the most severe complication arising from hyaluronic acid (HA) injection. To avoid skin necrosis, hyaluronidase should be injected along the course of the involved artery, to allow blood flow restoration. We evaluated the ability of hyaluronidase to degrade a HA filler in two simulated clinical situations-a compression case and an embolization case-to identify differences in the hyaluronidase injection. In the compression case, a bolus of HA filler was directly soaked in hyaluronidase solution; in the embolization case, a vein harvested from a living patient was filled with the same HA filler and then soaked in hyaluronidase. We then evaluated the quantity of HA remaining after 2 hr. While we found hydrolysis of HA in both cases, in the compression case, we detected almost complete hydrolysis, whereas in the embolization case we observed a reduction of the 60%. Our results support the hypothesis that vessel compression can be resolved with only one injection of hyaluronidase, while in the case of vascular embolization, repeated perivascular injections should be performed owing to the reduction of hyaluronidase activity.

Clinical Applications of Hyaluronidase

Hyaluronidases are enzymes that degrade hyaluronic acid, which constitutes an essential part of the extracellular matrix. Initially discovered in bacteria, hyaluronidases are known to be widely distributed in nature and have been found in many classes including insects, snakes, fish and mammals. In the human, six different hyaluronidases, HYAL1-4, HYAL-P1 and PH-20, have been identified. PH-20 exerts the strongest biologic activity, is found in high concentrations in the testicles and can be localized on the head and the acrosome of human spermatozoa. Today, animal-derived bovine or ovine testicular hyaluronidases as well as synthetic hyaluronidases are clinically applied as adjuncts to increase the bioavailability of drugs, for the therapy of extravasations, or for the management of complications associated with the aesthetic injection of hyaluronic acid-based fillers. Further applications in the fields of surgery, aesthetic medicine, immunology, oncology, and many others can be expected for years to come. Here, we give an overview over the molecular and cellular mode of action of hyaluronidase and the hyaluronic acid metabolism, as well as over current and potential future clinical applications of hyaluronidase.

In Vitro Evaluation of the Biological Availability of Hyaluronic Acid Polyethylene Glycols-Cross-Linked Hydrogels to Bovine Testes Hyaluronidase

During last years, hyaluronic acid- (HA-) based dermal fillers have grown rapidly and continuously, as reported by the American Society of Aesthetic Plastic Surgery (ASAPS). In fact, HA fillers are considered the gold standard technique for soft tissue augmentation, deep skin hydration, and facial recontouring, playing a key role as an alternative to plastic surgery. HA fillers are less invasive, more biocompatible, and safer and with a more natural and immediate result if compared to plastic surgery. Hence, the safety of HA-based dermal fillers plays a crucial role, mostly in terms of biocompatibility and adjustability in case of unpleasant results and side effects such as, tyndall effect, edema, or granulomas. Hyaluronidase is a naturally occurring enzyme, present in the human body, and can degrade HA fillers avoiding more severe complications. In this article, we analyzed the bioavailability of hyaluronidase degradation of five fillers of Neauvia® hydrogels line (MatexLab SA, Lugano, CH), composed of pure hyaluronic acid and based on PEGDE cross-linking (polyethylene glycol) technology that guarantees a higher biocompatibility and an optimal biointegration and rheological characteristics. The performed in vitro testing is based on the colorimetric determination of the N-acetyl-D-glucosamine (NAG) present in solution after incubation with hyaluronidase, determined at different time points in order to assess the kinetic of each product degradation (1h, 3h, 6h, 24h, 48h, 72h, 120h, and 168h). The aim of this study was to assess, in vitro, how the difference in HA content and PEGDE concentration of the analyzed fillers can influence the product biocompatibility, intended as product enzymatic clearance and duration in time. The results demonstrated that the method was reproducible and easy to perform and that all the analyzed fillers are naturally immediately available for hyaluronidase-mediated degradation.