Application of Nonsurgical Modalities in Improving Facial Aging

A Computational Study on Effects of PID Temperature Target and RF Frequency for PID-Controlled Nonablative RF Cosmetic Systems

BACKGROUND AND OBJECTIVES

Commonly adopted in cosmetic dermatology, nonablative radiofrequency (RF) devices convert high-frequency electromagnetic energy into thermal energy to induce a wound-healing response in skin tissue. However, differences in the electrical properties of different skin layers raise questions about the impact of different RF frequencies and target temperatures on treatment effectiveness. This paper presents a finite element analysis (FEA)-based computational study aimed at simulating and optimizing the effects of a proportional integral derivative (PID)-controlled RF cosmetic devices under different combinations of these two parameters during treatment.

STUDY DESIGN/MATERIALS AND METHODS

A 3D physical model for the application of a nonablative RF device was constructed using COMSOL, which included the human tissue and RF electrodes, electromagnetic and thermal boundary conditions, as well as the PID controller. FEA was performed for each of the twelve models with parameter combinations of three RF frequencies (0.1, 0.5, and 1 MHz) and three PID-controlled target temperatures (60°C, 65°C, and 70°C) plus one group without PID control. Treatment effectiveness was quantitatively assessed using the integration of tissue thermal damage fraction, i.e., thermal damage volume.

RESULTS

In the earlier stage of heating (0-10 s), higher RF frequency resulted in a larger thermal damage volume. At 10 s, among models with a temperature target of 70°C, there is a 6.04% difference between the thermal damage volume at RF frequencies of 1.0 and 0.1 MHz. In the later stage of heating(11-80 s), the impact of RF frequency decreases. The difference in thermal damage volume caused by higher temperature targets is more significant, at 80 s, among models with an RF frequency of 1.0 MHz, the 70°C model produces 1.15 and 1.36 times more tissue thermal damage than the 65°C and 60°C models.

CONCLUSION

PID controller has ensured treatment safety and uniformity, in exchange for some efficiency. Among 12 parameter combinations, the one with a temperature of 70°C and RF frequency of 1.0 MHz achieved the highest thermal damage volume, which could potentially result in the best esthetic effect. Considering users' different susceptibility to heat, engineers or physicians can select better temperature targets and RF frequencies to bring the desired cosmetic results based on thermal damage volume curves from this study.

A clinical study on the efficacy of high frequency therapy on nasolabial and periorbital wrinkles

The high-frequency generator is considered a collagen stimulator and skin revitalizer, however there are few studies exploring its effects in the field of rejuvenation and aesthetics. Thus, this study aimed to investigate the impact of high frequency generator therapy on facial aging. A total of 26 participants aged between 50 and 60 years were selected and received high frequency generator treatment for eight weeks. The evaluation was conducted using a combination of photographic records and assessment tools, including Rosenberg scale, perception and satisfaction with treatment evaluation, overall aesthetic improvement scale, and modified Fitzpatrick scale. The analysis conducted by the Global Aesthetic Improvement Scale yielded significant results. The Modified Fitzpatrick Wrinkle Scale showed that high frequency therapy led to statistically significant improvements in the appearance of nasolabial wrinkles (right T0: 1.48, T8: 0.87; left T0: 1.51, T8: 1.05) and periorbital wrinkles (right T0: 1.69, T8: 1.05; left T0: 1.71, T8: 1.08). In conclusion, high frequency generator therapy can be a highly effective tool for treating skin aging on the face, however, we recommend that future research includes control groups, and adopts objective measures to expand knowledge about the effects of high frequency.

Clinical applications of a novel poly-L-lactic acid microsphere and hyaluronic acid suspension for facial depression filling and rejuvenation

BACKGROUND

Poly L-lactic acid (PLLA) can stimulate fibrous tissue regeneration to exert a filling effect. However, severe inflammatory reactions and unsatisfactory effects remain a concern.

OBJECTIVE

Herein, we describe the mechanism of action, efficacy, and safety of PLLA microspheres in suspension (PLLA-b-PEG/HA) for facial contouring and soft tissue augmentation.

METHODS

PLLA-b-PEG/HA, ssynthesized by copolymerization with ethylene glycol, were suspended in hyaluronic acid (HA). Physiological verification was performed using scanning electron microscopy and X-ray computed tomography. PLLA-b-PEG/HA were subcutaneously injected into the dorsal region of 4-month-old rabbits. Ultrasound assessed volumetric capacity at 3 days and 1, 2, 4, and 12 weeks. The inflammatory response, collagen production, and HA degradation were evaluated. A retrospective case series of 10 patients who received PLLA-b-PEG/HA injections was conducted to assess long-term efficacy and safety.

RESULTS

PLLA-b-PEG exhibited a spherical structure with a smooth surface (20-45 μm diameter). In rabbits, implant site volume increased within 4 weeks, gradually decreasing thereafter. Fibrous capsules, microvessel density, and new collagen fiber formation progressively increased at 4, 12, and 26 weeks after injection. Clinical data demonstrated significant improvements in face contouring at months 3 and 12 after injection. All patients showed improved internal contours based on the Global Aesthetic Improvement Scale. After 12 months, 90% of the patients retained good shaping and support effects with minimal adverse reactions.

CONCLUSIONS

PLLA-b-PEG/HA demonstrated superior biocompatibility and facial regeneration potential, with outstanding dual collagen-stimulating properties. The clinical efficacy and safety of PLLA-b-PEG/HA have been validated and established as a promising therapeutic option.

Investigation of Appearance Anxiety Levels and Influencing Factors in Patients Undergoing Minimally Invasive Facial Cosmetic Procedures

OBJECTIVE

This study aimed to investigate appearance anxiety and its influencing factors in patients undergoing minimally invasive facial cosmetic procedures.

METHODS

A convenience sampling method was used to select 351 patients who attended the outpatient clinic of the Plastic Surgery Hospital, Chinese Academy of Medical Sciences from January to August 2023. Patients completed self-administered and social appearance anxiety questionnaires before treatment.

RESULTS

The mean appearance anxiety score was 2.49±0.85, indicating a moderate level of anxiety. Significant differences in appearance anxiety levels were observed based on age (p = 0.010), gender (p = 0.026), marital status (p = 0.032), number of children (p = 0.019), facial wrinkle removal procedures (p = 0.023), self-pleasure (p = 0.043), and special attention to the treatment area (p = 0.042). Multiple linear regression analysis identified facial wrinkle removal (p = 0.018), facial depression filling (p = 0.049), and special attention to the treatment area (p = 0.034) as significant factors.

CONCLUSION

Younger populations are more likely to seek improved appearance for better opportunities. The uncertainty of treatment outcomes may also increase social appearance anxiety in patients. Patients can reduce this anxiety by increasing their self-efficacy and self-confidence.

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 .

The application of basic SMAS rhytidectomy and comprehensive SMAS rhytidectomy

Rhytidectomy has made great progress in the past 50 years, especially after the proposition of the concept of superficial musculoaponeurotic system (SMAS). Our previous research had classified SMAS rhytidectomy into basic SMAS rhytidectomy (B-SMAS) and comprehensive SMAS rhytidectomy (C-SMAS) according to whether the treatment of SMAS aponeurosis is combined with retaining ligament, fat pad, mimetic muscles, etc. The purpose of this paper is to compare the outcomes of the 2 methods. Through multicenter collaborative research, 21 cases of B-SMAS and 18 cases of C-SMAS were collected. Photographs were taken pre- and post-operation for each patient, and the facial width of the lateral canthus level (upper face), the alar base level (middle face), and the oral commissure level (lower face) were measured. We compared the statistics of upper, middle, and lower face pre- and post-B-SMAS and C-SMAS to assess the ramifications of each operation. We used preoperative measurements minus corresponding postoperative measurements of specific operation to assess which position would acquire superior improvements. We also recruited 3 professional plastic clinicians to rate the ramifications of specific positions and approaches after pre- and post-photo comparing. Through comprehensive analyzing, we compared the improvements between B-SMAS and C-SMAS to assess which method is more beneficial concerning facial rejuvenation. Both B-SMAS and C-SMAS would acquire optimal changing concerning facial width in middle and lower face after operation (P < .05). Two methods all harvested better width changing effects in middle and lower face than upper face (P < .05). However, C-SMAS acquired better effects in middle and lower face than B-SMAS (P < .05). Both B-SMAS and C-SMAS are beneficial to facial rejuvenation. The effects in middle and lower face are better than upper face. In addition, C-SMAS may be more effective than B-SMAS.

Clinical and Histological Effects of Calcium Hydroxyapatite Filler in the Orofacial Region: A Study in Rats

BACKGROUND

Calcium hydroxyapatite (CaHA) dermal filler has been increasingly used in facial aesthetic procedures.

OBJECTIVE

To investigate clinical and histological changes associated with calcium hydroxyapatite (CaHA) dermal filler in the orofacial region.

MATERIALS AND METHODS

Forty-eight female Wistar rats were divided into CaHA and control groups. The material was applied in the ventral tongue and the submandibular region; the animals were euthanized after 7, 30, and 90 days.

RESULTS

After 7 days, yellowish nodules with a firm consistency were observed on the tongue. In 2 animals, the material migrated to the base of the tongue. Histopathological examination revealed CaHA spheres surrounded by an infiltrate, predominantly composed of macrophages. In the CaHA group, the percentage of collagen in the tongue and dermis was higher compared with the control group ( p < .05) at both 30 and 90 days. The thickness of the epidermis/dermis was also higher in the CaHA group ( p < .05). In 5 submandibular glands containing material, areas of edema and hyperemia were observed, along with infiltrates of neutrophils, lymphocytes, and plasma cells. Changes in the morphology of ducts and acini in adjacent regions were evident.

CONCLUSION

CaHA exhibits satisfactory properties for filling and collagen biostimulation in the tested regions. Further studies are required to explore the potential for migration and the glandular alterations.

The Redefinition and Volumization of the Lip Area with Hyaluronic Acid: A Case Series

Background: The increasing popularity of non-surgical cosmetic enhancements for the lower face and perioral area, particularly through hyaluronic acid (HA) fillers, reflects the growing desire for improved lip volume and definition. This study showcases the effects of a specific HA filler on lip fullness, shape, and overall perioral rejuvenation. Methods: We conducted a retrospective single-site observational analysis of adult female patients treated with Genefill Soft Fill HA injections in the lips and perioral areas. Both patient and physician satisfaction were evaluated using the Likert scale and Global Aesthetic Improvement Scale (GAIS), respectively. The outcomes for natural appearance, volume, and durability were assessed using a five-point scale. The patients were followed up with for up to six months to monitor any adverse events. Results: The cohort included thirteen female patients with an average age of 55.3 ± 8.3 years. Approximately 1.2 ± 0.4 mL of filler was used per patient. The results indicate high satisfaction, with scores above 4 for naturalness, volume, and durability. Over 92% of patients reported a significant improvement in appearance. No moderate or severe adverse events were reported. Conclusions: Genefill Soft Fill HA filler is both effective and safe for enhancing lip esthetics, with high satisfaction rates among recipients and no significant adverse events observed.

Facial Rejuvenation: A Global Trend of Dermatological Procedures in the Last Decade

Background

We aimed to track the global trend of cosmetic treatment outcomes for facial rejuvenation and the differences in modalities used in East Asian and Western populations.

Methods

Articles reporting on facial rejuvenation procedures (invasive/noninvasive) were identified in PubMed from 2013 to March 2023 and bibliometrically analyzed for type of published document, citation frequency, authors with most articles, author's affiliation, and frequency distribution of keywords.

Results

From 553 articles, most were published in 2021 (n = 86, 15.6%). Western countries (n = 323, 58.4%) contributed more than East Asian (n = 230, 41.6%), with more invasive interventions (n = 355, 64.2%) than noninvasive techniques (n = 198, 35.8%). Numbers of invasive techniques in West versus East Asian countries were 225 (40.7%) versus 135 (24.4%). Main indications were the reduction of facial wrinkles and antiageing treatments. Hyaluronic acid, fillers, and botulinum toxin were the main hotspots for invasive treatments, whereas laser, platelet-rich plasma, and radiofrequency were for noninvasive treatments. Nasolabial folds (13.4%) and glabellar lines (12.4%) were the top research hotspots in the East Asian and Western regions. Common adverse events were pain, erythema, swelling, and bruising. Approximately, 89.3% of publications were from single countries, whereas 10.7% of publications were from international collaborations. Most articles (n = 387; 69.95%) presented their findings using level II evidence. Dermatological surgery (IF = 2.914) had the greatest number of publications (n = 109; 19.71%).

Conclusions

The main hotspots were antiaging and youthfulness. This study provides a trend and a new perspective on the future research directions in the field of facial rejuvenation.

Potential benefits of adipose–derived SVF and MSCs to regenerate damaged tissues from alloplastic synthetic materials

Recent advancements in Plastic Surgery and Regenerative MedicineQuery have revolutionized tissue repair, remodeling, and regeneration. A promising approach involves Mesenchymal Stem cells and from the adipose–derived Stromal Vascular Fraction, aimed at improving tissue healing post the use of synthetic materials. This integration shows potential in mitigating adverse effects of synthetic materials like dermal fillers, offering new clinical interventions for tissue repair and regeneration. This article explores the benefits, complications, and applications of these technologies in Plastic Surgery and Cosmetic Medicine, focusing on their mechanisms of action and future perspectives.

 Level of evidence: Not ratable

An evaluation of the effectiveness of 'ULTRACOL 200' in enhancing nasolabial fold wrinkles through cutaneous repair

BACKGROUND

Injectable filler, a nonsurgical beauty method, has gained popularity in rejuvenating sagging skin. In this study, polydioxanone (PDO) was utilized as the main component of the ULTRACOL200 filler that helps stimulate collagenesis and provide skin radiant effects. The study aimed to evaluate and compare the effectiveness of ULTRACOL200 with other commercialized products in visually improving dermatological problems.

METHODS

Herein, 31 participants aged between 20 and 59 years were enrolled in the study. 1 mL of the testing product, as well as the quantity for the compared groups was injected into each participants face side individually. Subsequently, skin texture and sunken volume of skin were measured using ANTERA 3D CS imaging technology at three periods: before the application, 4 weeks after the initial application, and 4 weeks after the 2nd application of ULTRACOL200.

RESULTS

The final results of skin texture and wrinkle volume evaluation consistently demonstrated significant enhancement. Consequently, subjective questionnaires were provided to the participants to evaluate the efficacy of the testing product, illustrating satisfactory responses after the twice applications.

CONCLUSION

The investigation has contributed substantially to the comprehension of a PDO-based filler (ULTRACOL200) for skin enhancement and provided profound insight for future clinical trials.

Remodeling of facial soft tissue induced by simultaneous application of HIFES and synchronized radiofrequency provides nonsurgical lift of facial soft tissues

BACKGROUND

The application of radiofrequency (RF) and HIFES on the body provides improvement in skeletal muscle tissue, reduction in fatty tissue, reorganization of connective tissue, and skin texture improvement. However, overall facial appearance relies on both skin and underlying structures, specifically muscles and connective tissue which have to be treated as one unit to achieve proper care while preserving fatty layers that define youth facial appearance.

AIMS

The aim of this study is to find whether the effect of novel RF + HIFES is safe and can induce the lifting of soft tissue and overall improvement in facial appearance.

METHODS

In this study, 21 subjects were enrolled. The therapy was administered in four 20-min treatments on the forehead and cheeks. Photographs were evaluated by a Global Aesthetic Improvement Score (GAIS) and linear measurements of facial tissue lifting at 1- and 3-month follow-ups. Volumetric changes in the cheek area were investigated as well. The patients' satisfaction, safety, and comfort were documented throughout the study.

RESULTS

The data indicated improvement in overall facial appearance, and 23% of average lifting was found in brows (p = 3.14 × 10-12 ) and cheeks (p = 6.00 × 10-15 ). The assessment of digital photographs showed an improvement in 100% of patients at 3-month follow-up. The treatments were safe, accompanied by high therapy comfort and subject satisfaction of 98%.

CONCLUSIONS

The treatment by simultaneous RF and HIFES technology produces significant changes to the overall facial appearance, characterized by the lifting of facial tissues.

Subcutaneous injection of hyaluronic acid leading to emboliom and recanalization process monitored in real time by three-dimensional photoacoustic imaging

This study describes a method for real-time examination of the microvascular system based on the three-dimensional photoacoustic imaging system to prevent arterial complications, especially vascular embolism, during hyaluronic acid (HA) injections. Chicken embryos were used to simulate the superficial blood vessels of human skin, and then the target area was imaged by the photoacoustic imaging system for three-dimensional vascular imaging, and then the syringe and blood vessels were monitored, and the syringe angle and penetration depth were adjusted in time using an injection device to avoid puncturing the arterial vasculature and clogging the blood vessels. HA was then injected into smaller vessels on the dorsum of the tongue in mice and into thicker vessels on the dorsal portion of the tongue in rats to mimic embolization, and the post-operative recovery was reflected by the changes in the pixel dots of the extracted part of the blocked blood vessels, and it was observed that the blood flow in the area of the fine vessels was restored in about 3 days, whereas blood flow in the area of the large vessels was restored in only about 1 h. The method presented in this paper allows precise guidance of injectable filler HA, which has good application prospects in improving the safety of injection micro-plastic surgery and reducing the experience requirements for medical personnel.

Safety and efficacy of hyaluronic acid injectable filler in the treatment of nasolabial fold wrinkle: a randomized, double-blind, self-controlled clinical trial

INTRODUCTION

The injectable skin fillers available for soft tissue augmentation are constantly growing, providing esthetic surgeons with more options in the treatment of scars, lines, and wrinkles. Hyaluronic acid (HA)-derived injectable fillers are ideal to reduce the appearance of nasolabial folding. This study investigated the efficacy and safety of the commercially available HA filler from Maxigen Biotech Inc. (MBI-FD) in the treatment of nasolabial folds (NLFs).

METHODS

We analyzed 1,4-butanediol diglycidyl ether (BDDE) residues and injection force test and observed the protein content in MBI-FD, and then was cultured in fibroblast L929 cells and examined for cytotoxicity. Finally, 95 healthy participants underwent dermal filler injection therapy to evaluate the efficacy and safety for 24 and 52 weeks, respectively.

RESULTS

BDDE residues in MBI-FD was <0.125 µg/mL. MBI-FD was fitted using 27- and 30-G injection needles with an average pushing force of 14.30 ± 2.07 and 36.43 ± 3.11 N, respectively. Sodium hyaluronate protein in MBI-FD was 7.19 µg/g. The cell viabilities of 1× and 0.5× MBI-FD were 83.25% ± 3.58% and 82.23% ± 1.85%, respectively, indicating MBI-FD had no cytotoxicity, and decreased NLF wrinkles with no serious adverse events.

CONCLUSION

MBI-FD is an effective filler for tissue augmentation of the NLFs and may be a suitable candidate as an injectable dermal filler for tissue augmentation in humans in the future.

Imaging Features and Complications of Facial Cosmetic Procedures

Facial aesthetic procedures have become increasingly popular and complex, making knowledge of facial anatomy crucial for achieving desired outcomes without complications. Some of the most common procedures include blepharoplasty, bichectomy, face-lifts, facial implants, thread lifting, and fillers. Blepharoplasty and bichectomy are surgical procedures that respectively aim to restore youthful contours to the periorbita and create a slimmer lower face by removing Bichat fat from the maxillofacial region. Facial implants are used for aesthetic augmentation of the skeletal structure and restoration of facial contour by using biomaterials or autogenous bone grafts. Face-lift surgeries involve incisions and removal of excess skin, and thread lifts involve less invasive procedures performed by inserting threads beneath the skin, with the aim to lift the skin and thus reduce wrinkles and sagging. Fillers improve wrinkles and loss of facial volume, with biologic types made from animal, human, or bacterial sources (such as hyaluronic acid), while synthetic fillers include substances such as paraffin, silicone, calcium hydroxyapatite, polymethylmethacrylate microspheres, polyacrylamide hydrogel, hydroxyethyl-ethyl methacrylate, and poly-l-lactic acid. Synthetic fillers can be classified as rapidly resorbable (<12 months), slowly resorbable (<24 months), or permanent. Imaging modalities such as US, CT, and MRI can help identify and analyze each type of facial aesthetic procedure or filler, as well as their possible complications such as foreign-body granuloma, noninflammatory nodule, late intermittent persistent edema, filler migration, infection, or complications after removal of the buccal fat pad. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center The online slide presentation from the RSNA Annual Meeting is available for this article.

Poly-L-Lactic acid increases collagen gene expression and synthesis in cultured dermal fibroblast (Hs68) through the TGF-β/Smad pathway

OBJECTIVE

Poly-L-Lactic Acid (PLLA) is a synthetic polymer which possesses biocompatible and biodegradable properties, and is widely used in the clinical filler material. This study focuses on the potential role of PLLA on the collagen production of dermal fibroblasts and its mechanism.

METHODS

The dermal fibroblast Hs60 was treated with different concentration of PLLA. RT-qPCR was conducted for the determination of mRNA levels of collagen type I (COL1) alpha 1 (COL1A1), COL1 alpha 2 (COL1A2), elastin, matrix metalloproteinase 1 (MMP-1), tissue inhibitor of metalloproteinase 1 (TIMP-1), and TIMP-2. Procollagen Type I C-peptide (PIP) enzyme immunoassay (EIA) Kit assay was carried out to analyze procollagen production. Western Blot was employed to examine the effect of PLLA and transforming frown factor (TGF-β) receptor-specific inhibitor (SB431542) on protein levels of COL1A1 and TGF-β/Smad signaling pathway related proteins.

RESULTS

With the increase of PLLA concentration, the production of procollagen gradually increased, and both protein and mRNA levels of COL1A1 and COL1A2 gradually increased (p < 0.001). Elevated PLLA concentrations increased elastin, TIMP-1, and TIMP-2 levels and attenuated MMP-1 expression. PLLA increased TGF-β levels in a dose-dependently manner. p-Smad2 and p-Smad3 protein levels were also increased by PLLA, but the influences were reversed by SB431542 (p < 0.001). Similarly, increased levels of COL1A1, COL1A2, TIMP-1, and TIMP-2 caused by PLLA were significantly inhibited by SB431542, whereas MMP-1 was typically elevated (p < 0.001).

CONCLUSION

Poly-L-Lactic Acid promotes the collagen production of dermal fibroblasts by activating the TGF-β/Smad signaling pathway. The findings may lay a foundation for clinical material applications of PLLA.

Morpho-Functional Effect of a New Collagen-Based Medical Device on Human Gingival Fibroblasts: An In Vitro Study

Maintaining periodontal and peri-implant soft tissues health is crucial for the long-term health of teeth and dental implants. New biomedical strategies aimed at avoiding connective tissue alterations and related diseases (e.g., periodontitis and peri-implantitis) are constantly evolving. Among these, collagen-based medical products have proven to be safe and effective. Accordingly, the aim of the present study was to evaluate the effects of Dental SKIN BioRegulation (Guna S.p.a., Milan, Italy), a new injectable medical device composed of type I collagen of porcine origin, on primary cultures of human gingival fibroblasts (hGF). To this end, hGF were cultured on collagen-coated (COL, 100 µg/2 mL) or uncoated plates (CTRL) before evaluating cell viability (24 h, 48 h, 72 h, and 7 d), wound healing properties (3 h, 6 h, 12 h, 24 h, and 48 h), and the activation of mechanotransduction markers, such as FAK, YAP, and TAZ (48 h). The results proved a significant increase in cell viability at 48 h (p < 0.05) and wound closure at 24 h (p < 0.001) of hGF grown on COL, with an increasing trend at all time-points. Furthermore, COL significantly induced the expression of FAK and YAP/TAZ (p < 0.05), thereby promoting the activation of mechanotransduction signaling pathways. Overall, these data suggest that COL, acting as a mechanical bio-scaffold, could represent a useful treatment for gingival rejuvenation and may possibly help in the resolution of oral pathologies.

Expert Opinion on Non-Surgical Eyebrow Lifting and Shaping Procedures

Eyebrow elevation and reshaping are common concerns that we handle in everyday practice, and we have noticed that the trend is shifting from a medical concern to a cosmetic one. Several eyebrow lift methods are available, both invasive and non-surgical. The method of choice depends on several factors, such as patient expectations and beliefs, financial budget, acceptance of downtime and the available tools in the practice. In this article, we review the recent literature on non-surgical eyebrow lift methods to provide an overview of the current state of this field. We discuss seven different methods for eyebrow lift and reshaping, including botulinum toxin, dermal fillers, fractional radiofrequency, high-intensity focused ultrasound, thermo-mechanical ablation, lasers, and threads. Moreover, we provide practical insight into the procedure, injection techniques, expected results, and patient satisfaction rate.

Prospective bacterial and fungal sources of hyaluronic acid: A review

The unique biological and rheological properties make hyaluronic acid a sought-after material for medicine and cosmetology. Due to very high purity requirements for hyaluronic acid in medical applications, the profitability of streptococcal fermentation is reduced. Production of hyaluronic acid by recombinant systems is considered a promising alternative. Variations in combinations of expressed genes and fermentation conditions alter the yield and molecular weight of produced hyaluronic acid. This review is devoted to the current state of hyaluronic acid production by recombinant bacterial and fungal organisms.