An Overview of Soft Tissue Fillers for Cosmetic Dermatology: From Filling to Regenerative Medicine

Energy-based devices and hyaluronic acid filler, polymer filler, and threads: Cadaveric study

INTRODUCTION

The objective of this experiment was to investigate the thermal effects on hyaluronic acid fillers, PCL fillers, and PDO threads when exposed to controlled heat. This study aims to provide insights into how these materials respond to thermal energy, which is crucial for safe and effective cosmetic procedures involving combined modalities.

MATERIALS AND METHODS

Cadaveric tissue was utilized to simulate clinical conditions. Hyaluronic acid fillers were injected at approximately 1 mm and 5 mm thicknesses, with variations in G' value (high and low). PCL fillers were similarly injected in 1 mm and 5 mm thicknesses. PDO threads were also inserted. All materials were injected at a depth of 2 cm. A thermometer was used to measure heat penetration, and a multi-wavelength laser was applied to the tissue. The temperature was maintained at 60°C for 5 min to assess whether heat penetrated more than 3 cm in thickness. Observations were made regarding the heat distribution and any physical changes in the fillers and threads.

RESULTS

In thick layers, heat accumulated above the PCL filler without penetrating deeper layers. In thin layers, heat penetration was observed. For the HA fillers, heat energy was not blocked, regardless of the G' value or thickness. For the threads, no significant heat blockage effect was observed. For all materials, no visual changes were detected in any of the materials due to temperature exposure.

DISCUSSION

The findings suggest that the thickness and composition of fillers significantly influence heat penetration. Thick PCL fillers act as a thermal barrier, whereas thin PCL fillers allow deeper heat penetration. Hyaluronic acid fillers do not impede heat transfer, regardless of their physical properties. PDO threads do not exhibit any notable thermal resistance. These insights are essential for optimizing the safety and efficacy of combined filler and energy-based device treatments in esthetic medicine.

Aesthetic lip filler augmentation is not free of adverse reactions: lack of evidence-based practice from a systematic review

Introduction

In the last decades, dermal fillers have gained widespread acceptance for cosmetic purposes since their approval for different health conditions, including lip augmentation and aesthetic intervention of the face. Unfortunately, while filler lip procedures are performed using biomaterials with improved physical characteristics, they are not devoid of adverse drug reactions (ADRs), including those with late-onset.

Methods

This systematic aims to investigate the ADRs associated with lip augmentation procedures using dermal fillers. A systematic review search was conducted in Medline/PubMed, Scopus, Web of Science to answer the PEO question: What are the ADRs in patients undergoing lip augmentation procedures with dermal fillers, and how frequent are they?

Results

The risk of bias was assessed, and a systematic review was conducted. Nineteen studies were included. In total, 30 patients affected by filler lip ADRs were analyzed, of which 29 were females and only 1 was male with a mean age of 50.9 ± 12.8 years. Hyaluronic acid was the most commonly dermal filler used and granulomatous foreign body reaction was the most common filler lip reaction reported. The mean time between filler lip injection and granulomatous foreign body reaction onset was 57.9 ± 54 months (median 24 months).

Discussion

No study reported ADRs to regulatory authorities. Our results indicate that adverse reactions can occur even long-term after the aesthetic procedure. Therefore, ongoing short-term and long-term follow-up visits are essential, as biocompatible materials are not free from ADRs. Additionally, a lack of reporting ADRs to regulatory authorities has emerged, which is crucial for patient safety.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=534656, identifier: CRD42024534656.

A Personalized Protocol for Facial Rejuvenation Using Two Soft Hyaluronic Acid Fillers With High Cohesivity

Minimally invasive injectable dermal fillers are one of the most commonly used aesthetic treatments for facial soft tissue restoration. Different formulations may be used simultaneously to target multiple areas of concern. Due to differences in their rheological properties that directly impact the recommended injection technique and overall result, the formulations in the Aliaxin® line are each designed to target different soft facial tissues. This case series addresses two potential treatment approaches and a combination approach specifically developed to achieve harmony and promote a full but soft facial appearance. To reach this goal, we used two different formulations: Aliaxin® Shape and Restore (ASR) and Aliaxin® Global Performance (AGP). Four patients, 35-55 years received treatments with ASR, AGP, or both products. Utilizing the two protocols simultaneously achieved targeted support, lift, and volume, along with effective full facial softening and an authentic aesthetic outcome.

Manufacturing Process of Hyaluronic Acid Dermal Fillers

Hyaluronic acid (HA) fillers are extensively utilized in aesthetic medicine due to their biocompatibility, reversibility, and effectiveness in enhancing skin hydration, volume, and overall appearance. These fillers are predominantly produced through microbial fermentation, followed by a critical cross-linking process that enhances their longevity by resisting enzymatic degradation. This review provides a thorough examination of the manufacturing processes that differentiate HA fillers, with particular attention to the distinctions between biphasic and monophasic variants. Unlike previous studies, this review emphasizes the specific cross-linking techniques and their substantial impact on the fillers' rheological properties, such as elasticity and cohesiveness, which are crucial to their clinical performance and patient outcomes. Additionally, the review offers a comprehensive comparison of HA fillers with non-HA alternatives, including calcium hydroxylapatite, poly-l-lactic acid, and polymethyl methacrylate, highlighting the unique advantages and potential complications associated with each type. By presenting novel insights into the latest advancements and challenges in filler technology, this review aims to provide clinicians with a deeper understanding of filler properties, thereby guiding them in making informed decisions to optimize patient safety and aesthetic results.

Real-World Clinical Experience With an Allograft Adipose Matrix for Replacing Volume Loss in Face, Hands, and Body

INTRODUCTION

Real-world experience using an allograft adipose matrix (AAM) (Renuva) is presented as a series of seven cases demonstrating successful use of the matrix by nine expert cosmetic physicians across the United States. AAM is donated tissue that is aseptically processed without terminal irradiation into a transplantable adipose matrix that functions as a natural, versatile, and nonimmunogenic cushioning and volume-restoring tissue. When injected, the adipose matrix is replaced with the body's own fat cells and provides the cellular scaffold required for volume restoration and retention.

METHODS

Nine expert dermatologists were selected to share and discuss real-world patient cases using AAM. The experts discussed a variety of cases and selected 7 cases that demonstrated successful, novel use of AAM to present in this manuscript.

RESULTS

Experts agreed that the novel AAM is an easy-to-use, effective, and safe alternative to traditional fillers and fat grafting.

CONCLUSION

The use of the AAM is recommended for the face, hands, and other adipose tissue-containing parts of the body. The presented real-world cases provide guidance on how to identify ideal candidates to ensure optimal volume restoration results.

Are We Overlooking Harms of BDDE-Cross-Linked Dermal Fillers? A Scoping Review

1,4-Butanediol ether (BDDE) is widely used as a cross-linker for hyaluronic acid in dermal fillers. The purpose of this scoping review was to determine the state of knowledge about the behaviour of cross-linked substances and safety of BDDE application. The rationale behind the review came from the clinical experience of one of the authors (KS), who noticed adverse reactions after BDDE-linked hyaluronan application. The scoping review was conducted according to PRISMA-ScR guidelines. Out of 399 articles, 52 met the inclusion criteria. Data on study design, sample/population, aims, methodology, outcomes and funding were extracted. Results were charted according to 6 subtopics: rheological properties, hydrogel stability, BDDE toxicity, immunogenicity, tissue interactions and clinical studies. In vitro, cross-linked hydrogels were characterized as effective fillers in terms of viscosity and elasticity; however, previously uncharacterized by-products of the cross-linking reaction were found. Most in vivo studies reported increased dermis regeneration, vascularization and anti-inflammatory cytokine release after implantation of BDDE-cross-linked substances. In clinical studies, BDDE was shown to sensitize subjects to 1,6-hexanediol ether and other substances found in epoxy resin systems. Occupational dermatitis and hypersensitivity reactions were documented. Our review shows that BDDE may have long-term adverse effects, which are overlooked in the safety assessment of fillers. Reviews on BDDE conducted so far have mostly been sponsored by the industry, potentially leading to incomplete reporting of adverse effects. A review of the occurrence of allergic reactions after commercial dermal filler use and analysis of possibly harmful by-products of BDDE hyaluronan degradation are needed.Level of Evidence III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Investigating Facial Muscle Physiology Following Soft Tissue Filler Injections-A Surface-derived Electromyographic and Skin Vector Displacement Analytic Study

The use of hyaluronic acid-based soft tissue fillers has often been reported to modulate the muscle, that is, to cause myomodulation. To our knowledge, there has been so far no scientific study investigating the potential of hyaluronic acid-based soft tissue fillers to modulate or actually alter the function of facial muscles. To further assess this three-dimensional (3D) surface imaging and electromyography (EMG)-based prospective study investigated the changes of facial muscle contraction after injection of strategically placed hyaluronic acid-based soft tissue fillers to assess the actual validity of the term myomodulation. A total of 13 subjects with a mean age of 37.8 years (12 females, 1 male) were injected according to a predefined injection protocol. Surface EMG and 3D surface imaging were performed prior to the injection and 5 days after the injection. The results showed no significant change in the strength of the muscles (measured in μV) after injection of hyaluronic acid-based soft tissue fillers. However, horizontal and vertical skin displacement upon contraction of the zygomaticus major muscle changed significantly between baseline and follow-up, with a mean horizontal skin displacement increase from 3.2 to 4.1 mm. Upon contraction of the depressor anguli oris muscle, the horizontal skin displacement did not change significantly (2.15 vs. 2.05 mm), while vertical skin displacement increased significantly from 2.9 to 4.3 mm. The modification of the surrounding tissue caused an alteration of the vectorial skin displacement upon contraction of the muscle. A potential explanation could be the increased distance between the origin and insertion of the muscle due to the material deposition in the proximity of the relevant facial muscles, leading to a change of contraction vector.

Subcutaneous Application of a Gelatin/Hyaluronic Acid Hydrogel Induces the Production of Skin Extracellular Matrix

The development of injectable hydrogels with natural biopolymers such as gelatin (Ge) and hyaluronic acid (Ha) is widely performed due to their biocompatibility and biodegradability. The combination of both polymers crosslinked with N-Ethyl-N'-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) can be used as an innovative dermal filler that stimulates fibroblast activity and increases skin elasticity and tightness. Thus, crosslinked Ge/Ha hydrogels with different concentrations of EDC were administered subcutaneously to test their efficacy in young and old rats. At higher EDC concentrations, the viscosity decreases while the particle size of the hydrogels increases. At all concentrations of EDC, amino and carboxyl groups are present. The histological analysis shows an acute inflammatory response, which disappears seven days after application. At one and three months post-treatment, no remains of the hydrogels are found, and the number of fibroblasts increases in all groups in comparison with the control. In addition, the elastic modulus of the skin increases after three months of treatment. Because EDC-crosslinked Ge/Ha hydrogels are biocompatible and induce increased skin tension, fibroblast proliferation, and de novo extracellular matrix production, we propose their use as a treatment to attenuate wrinkles and expression lines.

Polynucleotides HPT for Asian Skin Regeneration and Rejuvenation

Introduction

Even lightly compromised skin may impact self-esteem and social behaviour. After intradermal infiltration, natural-origin Polynucleotides High Purification Technology (PN HPT) promote new collagen and extracellular matrix production, translating into a physiological correction of the ageing skin. The study aimed to explore the benefits of intradermal PN HPT on the four perceptual skin quality categories "Skin Tone Evenness", "Skin Surface Evenness", "Skin Firmness", and "Skin Glow" in a representative sample of 30 Asian subjects (mean age 40.2± 11.4 years old).

Methods

Study protocol: three intradermal injections of a PN HPT-based Class III CE-marked medical device at T0 (baseline assessment and first treatment session), T1 (four weeks after baseline), and T2 (eight weeks after baseline), with efficacy and safety evaluations at T1, T2, T3 (four months after baseline) and T4 (six months after baseline). Quantitative and qualitative assessments: 3D skin analysis system QuantifiCare and Global Aesthetic Improvement Scale (GAIS, Investigator and Patient subscales).

Results

PN HPT treatment led to a meaningful and statistically significant improvement of the skin surface, firmness, pigmentation, and radiance, with no early- or late-onset adverse events and benefits persisting up to the sixth-month visit in all subjects. At T4, 33% and 43% of treated subjects felt "Much Improved" and "Very Much Improved" (optimal result); 56% and 44% of treated subjects felt "Satisfied" or "Very Satisfied". At T4, the mean Investigator GAIS scores were 3.33 out of 5.0 for the "Skin Tone Evenness" skin quality perceptual category, 3.46 for the "Skin Surface Evenness" category, 3.61 for "Skin Firmness", and 3.45 per for the radiance determinant of the "Skin Glow" category.

Conclusion

Intradermal treatment with the PN HPT-based medical device led to a meaningful improvement of the skin surface, firmness, pigmentation, and radiance with complete safety. The aesthetic benefits persisted up to the sixth-month visit in all subjects.

A Covalently Cross-Linked Hyaluronic Acid/Carboxymethyl Cellulose Composite Hydrogel as a Potential Filler for Soft Tissue Augmentation

The use of fillers for soft tissue augmentation is an approach to restore the structure in surgically or traumatically created tissue voids. Hyaluronic acid (HA), is one of the main components of the extracellular matrix, and it is widely employed in the design of materials with features similar to human tissues. HA-based fillers already find extensive use in soft tissue applications, but are burdened with inherent drawbacks, such as poor thermal stability. A well-known strategy to improve the HA properties is to reticulate it with 1,4-Butanediol diglycidyl ether (BDDE). The aim of this work was to improve the design of HA hydrogels as fillers, by developing a crosslinking HA method with carboxymethyl cellulose (CMC) by means of BDDE. CMC is a water soluble cellulose ether, whose insertion into the hydrogel can lead to increased thermal stability. HA/CMC hydrogels at different ratios were prepared, and their rheological properties and thermal stability were investigated. The hydrogel with an HA/CMC ratio of 1/1 resulted in the highest values of viscoelastic moduli before and after thermal treatment. The morphology of the hydrogel was examined via SEM. Biocompatibility response, performed with the Alamar blue assay on fibroblast cells, showed a safety percentage of around 90% until 72 h.

Treating facial overfilled syndrome with impaired facial expression-Presenting clinical experience with ultrasound imaging

BACKGROUND

Facial overfilled syndrome is an adverse event following minimally invasive soft tissue filler injections. It presents in most cases as excess midfacial volume and/or as unnatural smile which is difficult to detect due to the absence of standardized evaluation methods.

OBJECTIVE

To showcase how to identify, evaluate, and treat facial overfilled syndrome by utilizing facial ultrasound and simultaneous hyaluronidase injections.

METHODS

Twenty-eight consecutive patients (26 females, 2 males) were enrolled in this study in which facial ultrasound was performed to evaluate the location previously implanted filler material. The position of the oral commissure was objectively measured in relation to bony landmarks, and the severity of lateral canthal lines was assessed by independent and blinded raters.

RESULTS

The material was identified in 35.7% inside the subdermal fatty layer, in 28.6% inside the deep supra-periosteal fatty layer, in 10.7% inside the fibrous layer deep to the subdermal fatty layer, whereas in 25.0%, the product was not possible to locate clearly inside one specific layer. On average, 81.6 I.U. [range: 75-150] of hyaluronidase were injected. Lateral canthal line severity was before the treatment 2.28 (1.4) and was after the hyaluronidase treatment 2.02 (1.3) with p = 0.578. The position of the oral commissure increased by 0.60 cm in vertical and by 0.30 cm in horizontal directions (both p < 0.001).

CONCLUSION

Facial overfilled syndrome following aesthetic soft tissue filler injections can present as excess midfacial volume but also as unnatural smile. Targeted hyaluronidase injections into the culprit pockets inside the midfacial soft tissues have shown to re-establish a natural smile, to reduce excess midfacial volume, and to decrease lateral canthal line severity.

Mesenchymal stem cells-based drug delivery systems for diabetic foot ulcer: A review

The complication of diabetes, which is known as diabetic foot ulcer (DFU), is a significant concern due to its association with high rates of disability and mortality. It not only severely affects patients’ quality of life, but also imposes a substantial burden on the healthcare system. In spite of efforts made in clinical practice, treating DFU remains a challenging task. While mesenchymal stem cell (MSC) therapy has been extensively studied in treating DFU, the current efficacy of DFU healing using this method is still inadequate. However, in recent years, several MSCs-based drug delivery systems have emerged, which have shown to increase the efficacy of MSC therapy, especially in treating DFU. This review summarized the application of diverse MSCs-based drug delivery systems in treating DFU and suggested potential prospects for the future research.

Injectable fillers: current status, physicochemical properties, function mechanism, and perspectives

With the increasing understanding of the aging process and growing desire for minimally invasive treatments, injectable fillers have great potential for correcting and rejuvenating facial wrinkles/folds and contouring the face. However, considering the increasing availability of multiple soft tissue fillers, it is important to understand their inherent biophysical features and specific mechanism. Thus, in this review, we aim to provide an update on the current injectable filler products and analyze and compare their critical physicochemical properties and function mechanisms for volume-filling. Additionally, future trends and development processes for injectable fillers are also proposed.

The effect of combined hyaluronic acid filler injection and radiofrequency treatment: A clinic histological analysis

BACKGROUND

Hyaluronic acid (HA) filler injections have increased in popularity. They are usually performed in combination with other treatment modalities, including lasers and energy-based devices, to enhance cosmetic results. Theoretically, HA and other filler injections should be performed after laser- or energy-based device treatments. In some instances, however, practitioners are asked to administer laser- or energy-based device treatment after HA dermal filler injection. There is a concerning possibility of HA filler degradation as a result of bulk heating generated by lasers or energy-based devices, especially radiofrequency (RF).

AIM

To evaluate the effect of RF treatment at different time points on HA degradation in vivo, using clinicohistological analysis.

PATIENTS/METHODS

Fourteen volunteers were recruited and received intradermal HA filler injections in four sites on the abdomen. One site served as the control, and the other three sites were treated with monopolar RF on the same day after injection, at 14 and 28 days post-injection. Skin biopsies were performed at baseline and 56 days after HA injection. Histopathological sections were reviewed for residual filler in the tissue.

RESULTS

The results showed that HA grading scores decreased in five (35.71%), one (7.14%), and one (7.14%) participants when RF was performed immediately, 14 and 28 days after injection, respectively.

CONCLUSION

In conclusion, RF treatment after HA filler injection may affect the integrity of the HA filler in the tissue, especially if RF treatment was performed on the same day after HA injection.

Human dermal fibroblast response to hyaluronic acid-based injectable dermal fillers: an in vitro study

Introduction

Hyaluronic acid (HA)-based injectable dermal fillers (IDFs) used in aesthetic procedures may increase fibroblast activity and ultimately improve subcutaneous tissue quality.

Aim

To further our understanding of fibroblast response to different commercial HA-based IDFs.

Material and methods

Normal human dermal fibroblasts (NHDFs) were cultured with four different commercially available HA-based IDFs to assess their effects on the synthesis of extracellular matrix components and regulators (type I collagen, type III collagen, elastin, and transforming growth factor (TGF)-β1) as well as pro-inflammatory and oxidative DNA damage markers (interleukin (IL)-1β and 8-hydroxy-2'-deoxyguanosine (8-OHdG)). The six biomarkers were measured in supernatants from NHDF cultures after 24 h, 48 h, and 72 h of exposure to HA-based IDFs.

Results

All tested IDFs elicited a higher release of type I collagen in NHDF culture supernatants, although Juvederm Voluma was found to induce the most pronounced increase. Agex Fill Ultra induced the highest production of type III collagen and elastin. Levels of TGF-β1 and type I collagen in cell culture supernatants were positively correlated to each other (r = 0.57, p < 0.05). Conversely, 8-OHdG concentrations were inversely associated with both type III collagen (r = -0.41, p < 0.05) and elastin (r = -0.46, p < 0.05).

Conclusions

Commercially available HA-based IDFs may elicit different in vitro fibroblast responses - a finding with potential implications in the prediction of their effects in aesthetic procedures. Our results also confirm that in vitro experiments may be viable tools for testing the effects of HA-based IDFs without resorting to animal studies.

Commentary: Facial Aesthetic Dermatological Procedures and Photoprotection in Chinese Populations

The medical literature on aesthetic dermatology has primarily focused on a light-skinned patient population, yet patients of darker skin types have different needs and priorities. In Chinese individuals, key concerns include altered pigmentation, which is perceived to age the individual, and also relates to the Chinese cultural standard of beauty of fair skin; many seek aesthetic treatment for this. Non-invasive cosmetic procedures such as lasers and injections are also gaining in popularity in the Chinese market, but this population is prone to hyperpigmentation as an adverse effect of such procedures. Considered and tailored approaches, both to primary concerns of photoaging and the side effects of cosmetic treatments, are warranted.

NOT SO "HAPPY BUMP": A complication due to hyaluronic acid

INTRODUCTION

The use of hyaluronic acid (HA) as a dermal filler is considered safe. However, as new brands come to the market, reports of adverse events are becoming more and more common.

OBJECTIVE

To describe a particular type of adverse effect that, unlike the erythematous, indurated, and painful nodules described in the literature as "angry red bumps," is characterized by noninflammatory, stony-like nodules that appear in sites previously treated with HA.

METHODS

The report of four patients who presented this complication, and the occurrence of two HA syringes from the same batch that had hardened the product inside at the time of filling.

CONCLUSION

The authors propose the nomenclature "happy bump" to group adverse reactions to HA that translate into noninflammatory nodules, with a stony consistency, appearing up to 4 weeks (recent) or after one month (late) in sites previously treated with AH.

Bioinspired Hydrogels as Platforms for Life-Science Applications: Challenges and Opportunities

Hydrogels, as interconnected networks (polymer mesh; physically, chemically, or dynamic crosslinked networks) incorporating a high amount of water, present structural characteristics similar to soft natural tissue. They enable the diffusion of different molecules (ions, drugs, and grow factors) and have the ability to take over the action of external factors. Their nature provides a wide variety of raw materials and inspiration for functional soft matter obtained by complex mechanisms and hierarchical self-assembly. Over the last decade, many studies focused on developing innovative and high-performance materials, with new or improved functions, by mimicking biological structures at different length scales. Hydrogels with natural or synthetic origin can be engineered as bulk materials, micro- or nanoparticles, patches, membranes, supramolecular pathways, bio-inks, etc. The specific features of hydrogels make them suitable for a wide variety of applications, including tissue engineering scaffolds (repair/regeneration), wound healing, drug delivery carriers, bio-inks, soft robotics, sensors, actuators, catalysis, food safety, and hygiene products. This review is focused on recent advances in the field of bioinspired hydrogels that can serve as platforms for life-science applications. A brief outlook on the actual trends and future directions is also presented.