Soft tissue fillers as non-specific modulators of adipogenesis: change of the paradigm?

Development of a PLA Polymer-Based Liquid Filler for Next-Generation Aesthetics

In regard to both natural aging and photoaging caused by UV radiation, a decrease in skin collagen and elastin fibers results in the loss of soft tissue volume. Biodegradable polymer fillers have been used to overcome this problem, but the slow rate of reconstruction and particle agglomeration has limited this approach. The DMSB01 filler, which consists of poly d-l-lactic acid (PDLLA) with a methoxy polyethylene glycol (mPEG) initiator, was created to address this issue. In this study, we assessed the reconstruction and dispersion of the DMSB01 filler in vitro, as well as its effect on collagen expression in rats. DMSB01 showed rapid reconstruction and excellent dispersion stability; gelation occurred within 5 min at 37 °C and remained stable. In an animal model, DMSB01 induced M2 macrophages, Transforming growth factor beta (TGF-β) expression, and significantly increased collagens I and III. Collagen recovery and wrinkle improvement were confirmed by the aging and photoaging models, and hematoxylin and eosin (H&E) staining was used to demonstrate the safety and biodegradability of DMSB01. DMSB01 was effective in terms of inducing collagen production and improving skin aging, and shows promise as an innovative ingredient to overcome the limitations of existing fillers.

Poly-D,L-Lactic Acid Fillers Increase Subcutaneous Adipose Tissue Volume by Promoting Adipogenesis in Aged Animal Skin

During aging, subcutaneous white adipose tissue (sWAT) thickness and the adipogenic potential of adipose-derived stem cells (ASCs) decline. Poly-D,L-lactic acid (PDLLA) fillers are commonly used to restore diminished facial volume. Piezo1 increases polarizing macrophages towards the M2 phenotype, which promotes the secretion of fibroblast growth factor 2 (FGF2), thereby increasing ASC survival. This study evaluated whether PDLLA enhances adipogenesis in ASCs by modulating M2 polarization in an in vitro senescence model and in aged animals. Lipopolysaccharide (LPS)-induced senescent macrophages showed decreased Piezo1, which was upregulated by PDLLA. CD163 (an M2 marker) and FGF2 were downregulated in senescent macrophages but were upregulated by PDLLA. We evaluated whether reduced FGF2 secretion from senescent macrophages affects ASCs by applying conditioned media (CM) from macrophage cultures to ASCs. CM from senescent macrophages decreased ERK1/2 and proliferation in ASCs, both of which were restored by CM from PDLLA-stimulated senescent macrophages. Adipogenesis inducers (PPAR-γ and C/EBP-α) were downregulated by CM from senescent macrophages but upregulated by CM from PDLLA-stimulated senescent macrophages in ASCs. Similar patterns were observed in aged animal adipose tissue. PDLLA increased Piezo1 activity, M2 polarization, and FGF2 levels. PDLLA also enhanced ERK1/2, cell proliferation, PPAR-γ, and C/EBP-α expression, leading to increased adipose tissue thickness. In conclusion, our study showed that PDLLA increased adipose tissue thickness by modulating adipogenesis.

Adipose Tissue, Regeneration, and Skin Health: The Next Regenerative Frontier

Adipose tissue, or fat compartments, has long been considered a storage depot and an energy source. However, a large part of new research, starting with the discovery of adipose-derived stem cells, has redirected this thinking toward the tremendous regenerative capacity that adipose tissue possesses when it is healthy. This has resulted in multiple technologies being explored with fat as a basis or with fat as a target aiming at the stimulation of new small hyperplastic adipose cells exuding adipokines and encouraging the proliferation of a whole host of progenitor cells that can have positive effects on many organ systems. One of these organ systems is skin, and there is a direct correlation with various fat compartments and skin health. Dermal fat tissue, also known as dermal white adipose tissue, is one such compartment that originates from dermal preadipocytes transdifferentiating into adipocytes and progenitor adipose cells under the right cues. The author of this paper discusses these potential cues, including injectable fillers, fat grafts, and topical formulations, and their capacity to impact skin health through the generation of healthy fat tissue. In addition, small molecules such as glucagon-like peptide-1 peptides and their impact on fat tissue are discussed. Adipose tissue is being recognized as the next regenerative frontier with exciting prospects ahead.

Level of Evidence 5 Therapeutic

Comparative Bulk RNA-Seq Analysis of Poly-l-Lactic Acid Versus Calcium Hydroxylapatite Reveals a Novel, Adipocyte-Mediated Regenerative Mechanism of Action Unique to PLLA

BACKGROUND

Injectable biostimulators are widely used to improve facial aging signs. This study was performed to compare the genetic pathways affected by 2 different injectable biostimulators.

METHODS

Randomized 13-week study (n = 21) comparing gene expression after poly l-lactic acid (PLLA-SCA) and calcium hydroxylapatite (CaHA-R) injections (baseline [BL] and Day 28) as treatment of nasolabial fold wrinkles. Punch biopsy was performed at BL and day 90; RNA was isolated, gene expression was analyzed, and bulk RNA sequencing performed. Data from both pathways were studied using the Search Tool for Retrieval of Interacting Genes/Proteins and Reactome databases.

RESULTS

Analysis at Day 0 and Day 90 showed differing gene regulation for PLLA-SCA and CaHA-R (after accounting for minor differences at BL, p < .05 at Day 90 for 9-12 genes). PLLA-SCA uniquely correlates with genes involved in adipocyte regeneration, while CaHA-R did not affect these genes. Clinically, this could translate to healthy fat replacement with an enhanced effect beyond the improvement of the collagen structure and a longer-lasting effect with PLLA-SCA. Furthermore, the adipokines that appear to be upregulated are regenerative with a positive impact on skin health.

CONCLUSION

PLLA-SCA has a novel and unique signature, which supports a potential regenerative mechanism of action through its role in the modulation of adipocyte function.

Decoding the Implications of Glucagon-like Peptide-1 Receptor Agonists on Accelerated Facial and Skin Aging

Following the advent of glucagon-like peptide-1 receptor agonists (GLP-1RAs), subsequent unintended effects such as accelerated facial aging and altered skin health have been noted. This review delves deeper into the causative underlying mechanisms and provides insights into the intricate relationship between GLP-1RAs, adipose tissue, and premature facial aging, thereby highlighting the need for a nuanced understanding of their effects on facial alterations and skin health. Studies exploring the potential effects of GLP-1RAs on facial alterations and offering insights into the possible underlying mechanisms, causes, and clinical implications were included. The accelerated facial aging and altered skin health observed in GLP-1RA patients appears to be multifactorial, involving loss of dermal and subcutaneous white adipose tissue, and altered proliferation and differentiation of adipose-derived stem cells (ADSCs), and impacts on the production and secretion of hormonal and metabolic factors. These changes compromise the structural integrity and barrier function of the skin and may lead to diminished facial muscle mass, further exacerbating the appearance of aging. The insights presented call for a paradigm shift in the clinical management of facial changes induced by GLP-1RAs, with a focus on treatment strategies aimed at targeting ADSC stimulation. These include autologous fat transfers to reintroduce cells rich in ADSCs for rejuvenation, composite fat grafting combining autologous fat with/without stromal vascular fraction, and the strategic use of soft tissue fillers for volume restoration and biostimulation. This review highlights the potential role of GLP-1RAs in modulating adipose tissue dynamics, thereby contributing to accelerated aging through metabolic, structural, and hormonal pathways.

LEVEL OF EVIDENCE: 5

Skin rejuvenation effect of the combined PDLLA and non cross-linked hyaluronic acid: A preliminary study

BACKGROUND

Skin aging is characterized by wrinkles, rough skin texture, pigmentation, facial erythema, and telangiectasia through structural and functional changes in the epidermis and dermis. Recently, injectable poly(D, L-lactic acid), a biodegradable polymer, has been used widely for skin rejuvenation.

AIMS

This study aims to assess the efficacy and safety of injectable dermal poly D, L-lactic acid) for skin rejuvenation.

PATIENTS/METHODS

A total of 16 patients who desired skin rejuvenation were included. All participants received two or three procedure sessions with a 4 weeks interval between sessions. Clinical and three-dimensional images at baseline, before each procedural session, and follow-up visits were obtained. Therapeutic effects were assessed by evaluating signs of aging skin and overall improvement by dermatologists and patients. Histologic examinations with special stains were performed on the posterior auricular areas of consenting patients at baseline and follow-up visits after injecting poly D L-lactic acid into the postauricular area as in the face.

RESULTS

Overall, statistically significant differences were observed in all signs of aging skin, such as fine wrinkles, skin texture, irregular pigmentation, telangiectasia, and facial erythema before and after treatments. Half (50%) of patients responded that there was more than 50% overall improvement. There were no severe adverse events. Histologic examination demonstrated increases in collagen and elastic fibers in the dermis.

CONCLUSIONS

Results of this preliminary study suggest that injectable dermal poly D, L-lactic acid can significantly affect skin rejuvenation without causing any serious adverse events.

Poly-L-Lactic Acid Fillers Improved Dermal Collagen Synthesis by Modulating M2 Macrophage Polarization in Aged Animal Skin

Poly-L-lactic acid (PLLA) fillers correct cutaneous volume loss by stimulating fibroblasts to synthesize collagen and by augmenting the volume. PLLA triggers the macrophage-induced activation of fibroblasts that secrete transforming growth factor-β (TGF-β). However, whether M2 macrophage polarization is involved in PLLA-induced collagen synthesis via fibroblast activation in aged skin is not known. Therefore, we evaluated the effect of PLLA on dermal collagen synthesis via M2 polarization in an H₂O₂-induced cellular senescence model and aged animal skin. H₂O₂-treated macrophages had increased expression levels of the M1 marker CD80 and decreased expression levels of the M2 marker CD163, which were reversed by PLLA. The expression levels of interleukin (IL)-4 and IL-13, which mediate M2 polarization, were decreased in H₂O₂-treated macrophages and increased upon the PLLA treatment. CD163, IL-4, and IL-13 expression levels were decreased in aged skin, but increased after the PLLA treatment. The expression levels of TGF-β, pSMAD2/SMAD2, connective tissue growth factor (CTGF), alpha-smooth muscle actin (α-SMA), collagen type 1A1 (COL1A1), and COL3A1 were also decreased in aged skin, but increased after the PLLA treatment. Moreover, PLLA upregulated phosphatidylinositol 3-kinase p85α (PI3-kinase p85α)/protein kinase B (AKT) signaling, leading to fibroblast proliferation. PLLA decreased the expression of matrix metalloproteinase (MMP) 2 and MMP3, which destroy collagen and elastin fibers in aged skin. The amount of collagen and elastin fibers in aged skin increased following the PLLA treatment. In conclusion, PLLA causes M2 polarization by increasing IL-4 and IL-13 levels and upregulating TGF-β expression and collagen synthesis in aged skin.

Effects of Polynucleotide Dermal Filler in the Correction of Crow's Feet Using an Antera Three-Dimensional Camera

BACKGROUND

Dermal fillers are gaining interest for tissue enlargement and skin improvement. Among them, polynucleotides have demonstrated multiple skin beneficial effects. The effects of polynucleotide fillers were objectively evaluated using an Antera 3D camera, subjectively evaluated by participants and investigators.

METHODS

Thirty subjects with crow's feet were enrolled in the study. The subjects received polynucleotide filler for crow's feet. Crow's feet grading score (CFGS), global esthetic improvement scale (GAIS), and Antera 3D imaging results were evaluated.

RESULTS

Twenty-eight subjects (93.3%) completed the study. An improvement in CFGS compared with that at baseline (p < 0.001) was observed 18 weeks after the first injection of polynucleotides. Additionally, at the final visit, there were improvements in wrinkle, texture, pore, depression, and Hb values compared with those at baseline (p < 0.05). However, no significant difference in melanin level was detected between the initial and final visits.

CONCLUSIONS

Improvements in wrinkles, pores, texture, depression, and Hb level after polynucleotide filler injection were verified by objective and subjective evaluations. To the best of our knowledge, this is the first report on the objective evaluation of polynucleotide fillers in crow's feet using the Antera 3D camera.

LEVEL OF EVIDENCE IV

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 .

Comparative Evaluation of Safety and Efficacy of a Novel Hyaluronic Acid-polynucleotide/Poly-L-lactic Acid Composite Dermal Filler

BACKGROUND

Poly-L-lactic acid (PLLA) is widely used in tissue engineering. The natural polymer hyaluronic acid (HA) shows excellent biocompatibility and affects cell signaling, proliferation, and differentiation. In addition, a polynucleotide (PN) induces cell growth of human skin fibroblasts and osteoblasts.

OBJECTIVE

In this study, we evaluated the properties, safety, and efficacy of a novel composite filler consisting of cross-linked HA with PN in combination with monodisperse PLLA microspheres manufactured using Inventage Lab Precision Particle Fabrication method.

MATERIALS AND METHODS

The composition of the filler and characteristics of the microspheres were examined via scanning electron microscopy, particle size analysis, gel permeation chromatography, and rheology and osmolality measurement. Additionally, safety and efficacy of HA-PN/PLLA composite filler were conducted in in vitro and in vivo.

RESULTS

Analysis of PLLA microspheres revealed spherical surfaces and a narrower particle size distribution than that in PLLA filler. HA-PN/PLLA composite filler had higher viscosity and elasticity values and similar osmolality as compared to those of HA and PN fillers. The nontoxicity in in vitro and in vivo tests reflected that the composite filler may be safe for human use. In addition, the composite filler maintained a more stable volume than did HA filler for 24 weeks after administration in HWY/Slc hairless rats. Furthermore, the results support the effect of HA-PN/PLLA in restoring skin structure.

CONCLUSION

Altogether, these data suggest that the novel composite filler might be a safe and effective option in terms of tissue integration, clinical management during delivery and high esthetic durability.

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 .

A new phytocosmetic preparation from Thymus vulgaris stimulates adipogenesis and controls skin aging process: In vitro studies and topical effects in a double-blind placebo-controlled clinical trial

BACKGROUND

The use of the injectable products for soft tissue augmentation and treatment of skin aging is an uncomfortable, invasive and related to several complications, and chronic reactions, mainly after long-term application. Efforts to develop new topically active anti-aging products with fewer adverse effects are a huge challenge that should be faced.

AIMS

We evaluated the anti-aging effects of a phytocosmetic preparation containing Thymus vulgaris associated with lecithin (ThymLec) on the facial wrinkles, expression lines, and face oval remodeling using a double-blind placebo-controlled clinical trial and in vitro cell culture assays.

METHODS

A clinical trial was conducted to evaluate the effects of ThymLec 2% on the area, length, and depth of the perioral and crow's feet wrinkles, nasolabial and smile lines, as well as face oval remodeling in female volunteers using a sophisticated Bio3D Structured-light Scanner. In the in vitro studies using 3T3-L1 mouse embryonic fibroblasts, adiponectin was measured by immunoenzymatic assay, adipogenesis by the AdipoRed reagent method, and the PPAR-γ expression by RT-PCR analysis.

RESULTS

Topical treatment with ThymLec 2% reduced facial wrinkles and expression lines promoting a face oval remodeling. In the in vitro studies, ThymLec upregulated the PPAR-γ expression increasing adiponectin production and stimulating the adipogenesis process.

CONCLUSIONS

The phytocosmetic preparation containing Thymus vulgaris and lecithin is an innovative and safe topical anti-aging product promoting fat tissue augmentation by adipogenesis stimulation via the upregulation of PPAR-γ expression and adiponectin production.

[Paradigm shift in understanding hyaluronic acid filler effects]

Hyaluronic acid (hyaluron; HA) is an important constituent of the extracellular matrix and has an age-dependent decrease in tissue concentration. While natural HA is rapidly degraded, filler cross-linked HA achieve a half-life of 6-12 months. Such fillers enjoy increasing popularity in esthetic medicine and are versatile tools. Although HA fillers can activate fibroblasts it is of minor importance for long-term results. Fillers are injected into subcutaneous adipose tissue. Their interaction with somatic stem cells and mature adipocytes has gained increasing interest. Cross-linked HA can indeed support proliferation of pre-adipocytes, stimulate their differentiation into mature adipocytes and protect the mature cells from senescence, apoptosis and lipolysis. This view offers a new perspective on the development of future fillers for esthetic medicine.

Tissue Mechanics in Haired Murine Skin: Potential Implications for Skin Aging

During aging, the skin undergoes changes in architecture and composition. Skin aging phenotypes occur due to accumulated changes in the genome/epigenome, cytokine/cell adhesion, cell distribution/extracellular matrix (ECM), etc. Here we review data suggesting that tissue mechanics also plays a role in skin aging. While mouse and human skin share some similarities, their skin architectures differ in some respects. However, we use recent research in haired murine skin because of the available experimental data. Skin suffers from changes in both its appendages and inter-appendage regions. The elderly exhibit wrinkles and loose dermis and are more likely to suffer from wounds and superficial abrasions with poor healing. They also have a reduction in the number of skin appendages. While telogen is prolonged in aging murine skin, hair follicle stem cells can be rejuvenated to enter anagen if transplanted to a young skin environment. We highlight recent single-cell analyses performed on epidermis and aging human skin which identified new basal cell subpopulations that shift in response to wounding. This may be due to alterations of basement membrane stiffness which would change tissue mechanics in aging skin, leading to altered homeostatic dynamics. We propose that the extracellular matrix (ECM) may play a key role as a chemo-mechanical integrator of the multi-layered senescence-associated signaling pathways, dictating the tissue mechanical landscape of niche microenvironments in aging phenotypes. We show examples where failed chemo-mechanical signaling leads to deteriorating homeostasis during skin aging and suggest potential therapeutic strategies to guide future research to delay the aging processes.

Comparative Evaluation of the Effectiveness of Novel Hyaluronic Acid-Polynucleotide Complex Dermal Filler

HA (Hyaluronic acid) filler, the most commonly used dermal filler, causes several side effects. HA-PN (Hyaluronic acid-Polynucleotide), a new composite filler, has excellent biocompatibility and induces tissue regeneration. In this study, we compare the efficacies and safety profiles of these fillers. The characteristics of HA and HA-PN fillers were compared using scanning electron microscopy and rheometry. No morphological difference was noted between the fillers. However, the latter had higher viscosity and elasticity values. The HA-PN filler induced higher cell migration than the HA filler in a wound healing assay. It was also found to stimulate better collagen synthesis in human and mouse fibroblasts. The HA and HA-PN fillers were injected into SKH1 hairless mice to determine changes in their volume for up to 24 weeks. Increased cell migration and collagen synthesis were observed in mice injected with the HA-PN complex filler. Although the safety and durability of the HA and HA-PN fillers were similar, the latter induced a lower transient receptor potential vanilloid 4 expression and caused less stimulation upon injection. In conclusion, HA-PN complex fillers can stimulate fibroblast growth and facilitate volume growth and skin regeneration.

Hydrogels in adipose tissue engineering-Potential application in post-mastectomy breast regeneration

Current methods of breast reconstruction are associated with significant shortcomings, including capsular contracture, infection, rupture, the need for reoperation in implant-based reconstruction, and donor site morbidity in autologous reconstruction. These limitations result in severe physical and psychological issues for breast cancer patients. Recently, research has moved into the field of adipose tissue engineering to overcome these limitations. A wide range of regenerative strategies has been devised utilising various scaffold designs and biomaterials. A scaffold capable of providing appropriate biochemical and biomechanical cues for adipogenesis is required. Hydrogels have been widely studied for their suitability for adipose tissue regeneration and are advantageous secondary to their ability to accurately imitate the native extracellular matrix. The aim of this review was to analyse the use of hydrogel scaffolds in the field of adipose tissue engineering.

Aesthetic dermatology: What's new, what's true?

Aesthetic dermatology (AD) is a rapidly growing subspecialty of dermatology. The acceptance of AD in scientific community and the society is associated with its competence, efficiency, and seriousness. This review highlights some recent developments toward new tools, techniques, and understanding in the field of AD. Analyzing the specific needs of patients and assessing the effect by objective measurements is important for further progress. For long time ignored, white adipose tissue has gained increasing interest in biology and rejuvenation. Characterization of dermal and subcutaneous white adipose tissue has made progress. The interaction of hyaluronic acid and calcium hydroxyl apatite (CaHA) fillers with adipocytes could be responsible for clinical efficacy. New developments of oral collagen treatment and highly diluted CaHA to contour the body outside the face will be discussed. Submental contouring using purified desoxycholic acid is another new development.

Adipose tissue, fillers, and skin tightening

The role of adipose tissue has long been underestimated in esthetic dermatology. With the development of liposculpture and lipolysis, subcutaneous adipose tissue has gained an increasing interest. Harvested tissue has been used for lipofilling. In recent years, a better understanding of adipocyte physiology and its role in aging opened a new road for targeted treatments. Subcutaneous adipose tissue is no longer an innocent bystander in the combat of aging and the correction in esthetics. Adipose tissue is of importance for metabolic function and thermoregulation. Adipose tissue is involved in inflammation. Adipose tissue is heterogeneous in sense of function, color and size of adipocytes. The tissue is an important source of somatic stem cells.

An in vitro and in vivo study on the properties of hollow polycaprolactone cell-delivery particles

The field of dermal fillers is evolving rapidly and numerous products are currently on the market. Biodegradable polymers such as polycaprolactone (PCL) have been found to be compatible with several body tissues, and this makes them an ideal material for dermal filling purposes. Hollow PCL spheres were developed by the Council for Scientific and Industrial Research (CSIR) to serve both as an anchor point and a "tissue harbour" for cells. Particles were tested for cytotoxicity and cell adherence using mouse embryo fibroblasts (MEF). MEFs adhered to the particles and no significant toxic effects were observed based on morphology, cell growth, cell viability and cell cycle analysis, suggesting that the particles are suitable candidates for cell delivery systems in an in vivo setting. The objective of providing a "tissue harbour" was however not realized, as cells did not preferentially migrate into the ported particles. In vivo studies were conducted in BALB/c mice into whom particles were introduced at the level of the hypodermis. Mice injected with PCL particles (ported and non-ported; with or without MEFs) showed evidence of local inflammation and increased adipogenesis at the site of injection, as well as a systemic inflammatory response. These effects were also observed in mice that received apparently inert (polystyrene) particles. Ported PCL particles can therefore act as a cell delivery system and through their ability to induce adipogenesis, may also serve as a dermal bulking agent.

Hyaluronan in adipogenesis, adipose tissue physiology and systemic metabolism

Hyaluronic acid (HA, also known as hyaluronan), is a non-sulfated linear glycosaminoglycan polymer consisting of repeating disaccharide units of d-glucuronic acid and N-acetyl-d-glucosamine abundantly present in the extracellular matrix. The sizes of hyaluronic acid polymers range from 5000 to 20,000,000 Da in vivo, and the functions of HA are largely dictated by its size. Due to its high biocompatibility, HA has been commonly used as soft tissue filler as well as a major component of biomaterial scaffolds in tissue engineering. Several studies have implicated that HA may promote differentiation of adipose tissue derived stem cells in vitro or in vivo when used as a supporting scaffold. However, whether HA actually promotes adipogenesis in vivo and the subsequent metabolic effects of this process are unclear. This review summarizes some recent publications in the field and discusses the possible directions and approaches for future studies, focusing on the role of HA in the adipose tissue.

Fillers and Facial Fat Pads

Fillers are used for facial sculpturing and anti-ageing treatments with increasing popularity. The optimal outcome of any filler treatment depends upon different factors: exact indication, known limitations, filler product, and filler placement. For volumizing effect and longevity of procedures, however, the interaction of fillers and facial fat pads seems to be crucial. Here, we will review the optimum filler injections for facial applications in relationship to new data and concepts concerning facial fat pads anatomy and physiology. Such a view will us enable to provide optimum results in aesthetic procedures.

Consensus Recommendations for Combined Aesthetic Interventions in the Face Using Botulinum Toxin, Fillers, and Energy-Based Devices

BACKGROUND

The aging process is a complex interplay of intrinsic and extrinsic factors across multiple layers of the face. Accordingly, combining aesthetic interventions targeting different manifestations of aging often leads to better results than single modalities alone. However, no guidelines for a pan-facial approach using multiple interventions have been published to date.

OBJECTIVE

To develop consensus recommendations for the optimal combination and ideal sequence of botulinum toxin (BoNT), hyaluronic acid, calcium hydroxylapatite, and microfocused ultrasound with visualization (MFU-V) in persons of all Fitzpatrick skin types.

METHODS AND MATERIALS

Fifteen specialists convened under the guidance of a certified moderator. Consensus was defined as approval from 75% to 94% of all participants, whereas agreement of ≥95% denoted a strong consensus.

RESULTS

Optimal aesthetic treatment of the face begins with a thorough patient assessment and an individualized treatment plan. Spacing consecutive treatments 1 to 2 weeks apart allows for resolution of side effects and/or to assess results. For same-day treatments, BoNT and fillers may be performed together in either sequence, whereas MFU-V is recommended before injectable agents.

CONCLUSION

Expert consensus supports a combination approach using multiple modalities in specific sequence for the safe and effective treatment of the aging face.

Influence of the Dermis Thickness on the Results of the Skin Treatment with Monopolar and Bipolar Radiofrequency Currents

Electrically layered tissue structure significantly modifies distribution of radiofrequency (RF) current in the dermis and in the subcutaneous adipose tissue comparing to that in a homogeneous medium. On the basis of the simple model of RF current distribution in a two-layer skin containing dermis and subcutis, we assess the influence of the dermal thickness on the current density in different skin layers. Under other equal conditions, current density in the dermis is higher for the skin having thinner dermis. This contradicts the main paradigm of the RF theory stating that treatment results are mainly dependent on the maximal temperature reached in a target tissue, since the best short- and long-term clinical results of RF application to the skin were reported in the areas having thicker dermis. To resolve this contradiction, it is proposed that the long-term effect of RF can be realized through a structural modification of the subcutaneous fat depot adjacent to the treated skin area. Stimulation of these cells located near the interface dermis/subcutis will demand the concentration of applied RF energy in this area and will require the optimal arrangement of RF electrodes on the skin surface.

Skin aging: are adipocytes the next target?

Dermal white adipose tissue (dWAT) is increasingly appreciated as a special fat depot. The adipocytes in this depot exert a variety of unique effects on their surrounding cells and can undergo massive phenotypic changes. Significant modulation of dWAT content can be observed both in intrinsically and extrinsically aged skin. Specifically, skin that has been chronically photo-damaged displays a reduction of the dWAT volume, caused by the replacement of adipocytes by fibrotic structures. This is likely to be caused by the recently uncovered process described as "adipocyte-myofibroblast transition" (AMT). In addition, contributions of dermal adipocytes to the skin aging processes are also indirectly supported by spatial correlations between the prevalence of hypertrophic scarring and the appearance of signs of skin aging in different ethnic groups. These observations could elevate dermal adipocytes to prime targets in strategies aimed at counteracting skin aging.

Dermal adipocytes and hair cycling: is spatial heterogeneity a characteristic feature of the dermal adipose tissue depot?

Adipocytes are widely distributed in the dermis, in a unique fat depot referred to as dermal white adipose tissue (dWAT). In rodents, dWAT is present as widespread thin layers, whereas in pigs and humans, it is present in clusters referred to as 'dermal cones' around the pilosebaceous units. This distinct layer of fat cells located above the subcutaneous white adipose tissue is important for proper hair follicle (HF) cycling in rodents. Murine HFs produce spatially restricted synchronous patches after their second postnatal cycle which correlates with the spatial heterogeneity of murine dWAT. Similarly, the cycling of HFs in humans may also be related to the spatial distribution of dWAT, making the difference between murine and human HF cycling of more quantitative than of qualitative nature. This should allow the production of small spatially correlated HF patches in human skin, and we propose that this process can be regulated by paracrine signalling involving a number of signalling modules, including the hedgehog pathway. This pathway is an established player in HF cycling, but is also involved in the regulation of adipogenesis and may therefore be a key regulator of the process across species. We also suggest that the spatial heterogeneity of dWAT is connected not only to HF cycling, but may also be related to other physiological and pathological processes in the skin.