Poly-D,L-Lactic Acid Filler Increases Extracellular Matrix by Modulating Macrophages and Adipose-Derived Stem Cells in Aged Animal Skin

Fibroblast growth factor signaling in macrophage polarization: impact on health and diseases

Fibroblast growth factors (FGFs) are a versatile family of peptide growth factors that are involved in various biological functions, including cell growth and differentiation, embryonic development, angiogenesis, and metabolism. Abnormal FGF/FGF receptor (FGFR) signaling has been implicated in the pathogenesis of multiple diseases such as cancer, metabolic diseases, and inflammatory diseases. It is worth noting that macrophage polarization, which involves distinct functional phenotypes, plays a crucial role in tissue repair, homeostasis maintenance, and immune responses. Recent evidence suggests that FGF/FGFR signaling closely participates in the polarization of macrophages, indicating that they could be potential targets for therapeutic manipulation of diseases associated with dysfunctional macrophages. In this article, we provide an overview of the structure, function, and downstream regulatory pathways of FGFs, as well as crosstalk between FGF signaling and macrophage polarization. Additionally, we summarize the potential application of harnessing FGF signaling to modulate macrophage polarization.

Poly‐d,l‐lactic acid‐enhanced atrophic scar treatment via transdermal microjet drug delivery in Asians

BACKGROUND

Acne vulgaris often results in permanent scars, with atrophic scars being the most common type and posing a significant therapeutic challenge due to their prevalence and impact on patients' quality of life. Various treatment options exist, including the use of poly-d,l-lactic acid delivered via different methods.

OBJECTIVE

This study aimed to assess the efficacy and safety of poly-d,l-lactic acid delivered via laser-assisted needle-free microjet injection for treating atrophic scars.

METHODS

Five Korean participants with atrophic facial scars were recruited. Poly-d,l-lactic acid solution was administered via the Mirajet system in five sessions, with clinical assessments conducted at baseline, before each session, and at 12-week and 22-week follow-ups. Outcome measures included the Global Aesthetic Improvement Scale and patient satisfaction scores.

RESULTS

Positive results were observed at the 12-week and 22-week follow-ups, with high patient satisfaction and improvements in atrophic scars and skin texture. Mild discomfort and transient side effects were reported, with no adverse events observed during the follow-up period.

CONCLUSION

Poly-d,l-lactic acid delivered by a laser-assisted needle-free microjet injector was judged to be effective for improving atrophic the facial area. Further research, particularly through randomized controlled trials, is needed to validate these findings and assess the longer-term safety and sustainability of outcomes.

Radiofrequency Treatment Attenuates Age-Related Changes in Dermal-Epidermal Junctions of Animal Skin

The dermal-epidermal junction (DEJ) is essential for maintaining skin structural integrity and regulating cell survival and proliferation. Thus, DEJ rejuvenation is key for skin revitalization, particularly in age-related DEJ deterioration. Radiofrequency (RF) treatment, known for its ability to enhance collagen fiber production through thermal mechanisms and increase heat shock protein (HSP) expression, has emerged as a promising method for skin rejuvenation. Additionally, RF activates Piezo1, an ion channel implicated in macrophage polarization toward an M2 phenotype and enhanced TGF-β production. This study investigated the impact of RF treatment on HSP47 and HSP90 expression, known stimulators of DEJ protein expression. Furthermore, using in vitro and aged animal skin models, we assessed whether RF-induced Piezo1 activation and the subsequent M2 polarization could counter age-related DEJ changes. The RF treatment of H2O2-induced senescent keratinocytes upregulated the expression of HSP47, HSP90, TGF-β, and DEJ proteins, including collagen XVII. Similarly, the RF treatment of senescent macrophages increased Piezo1 and CD206 (M2 marker) expression. Conditioned media from RF-treated senescent macrophages enhanced the expression of TGF-β and DEJ proteins, such as nidogen and collagen IV, in senescent fibroblasts. In aged animal skin, RF treatment increased the expression of HSP47, HSP90, Piezo1, markers associated with M2 polarization, IL-10, and TGF-β. Additionally, RF treatment enhanced DEJ protein expression. Moreover, RF reduced lamina densa replication, disrupted lesions, promoted hemidesmosome formation, and increased epidermal thickness. Overall, RF treatment effectively enhanced DEJ protein expression and mitigated age-related DEJ structural changes by increasing HSP levels and activating Piezo1.

Facial Skin Rejuvenation Using Poly-dl-Lactic Acid Injected With a Laser-Generated Needle-Free Microjet Injector

BACKGROUND

A laser-induced needle-free microjet injector was developed for rapid, high-speed drug delivery of microliters into the skin.

OBJECTIVE

This study evaluated the clinical rejuvenation effect of repeated dermal injections of the collagen simulator poly-dl-lactic acid (PDLA) using a laser-induced needle-free microjet injector.

METHODS

Five PDLA injection sessions using a laser-induced needle-free microjet injector were conducted in patients concerned about aging skin. Facial uplifting, darkness, redness, roughness, pore size, subjective satisfaction, and side effects were evaluated before each session and 4 weeks after treatment completion. Histological evaluation was also performed with immunohistochemical staining of collagen and elastic fibers.

RESULTS

The clinical results of 27 female patients were evaluated. The treatment resulted in a noticeable skin surface uplifting (0.711 ± 0.42 mm) and significant improvements in darkness (p = .013), redness (p = .009), and roughness (p = .036), with no significant difference in the pore size (p = .770). Patients were reported being satisfied with the overall therapeutic effects, despite mild and tolerable adverse effects. Histological findings revealed growth and thickening of collagen and elastic fibers, with marked increase in collagen I and III levels.

CONCLUSION

Repeated dermal injections of PDLA using a laser-induced microjet injector offer excellent drug delivery, achieving high efficacy in skin rejuvenation, patient satisfaction, and safety.

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.

Needle-Free Jet Injection of Poly-(Lactic Acid) for Atrophic Acne Scars: Literature Review and Report of Clinical Cases

Acne scars, particularly atrophic ones, present a persistent challenge in cosmetic medicine and surgery, requiring extended and multifaceted treatment approaches. Poly-(lactic acid) injectable fillers show promise in managing atrophic acne scars by stimulating collagen synthesis. However, the utilization of needle-free injectors for delivering poly-(lactic acid) into scars remains an area requiring further exploration. In this article, a summary of the latest advancements in needle-free jet injectors is provided, specifically highlighting the variations in jet-producing mechanisms. This summary emphasizes the differences in how these mechanisms operate, offering insights into the evolving technology behind needle-free injection systems. The literature review revealed documented cases focusing on treating atrophic acne scars using intralesional poly-(lactic acid) injections. The results of these clinical studies could be supported by separate in vitro and animal studies, elucidating the feasible pathways through which this treatment operates. However, there is limited information on the use of needle-free jet injectors for the intradermal delivery of poly-(lactic acid). Clinical cases of atrophic acne scar treatment are presented to explore this novel treatment concept, the needle-free delivery of poly-(lactic acid) using a jet pressure-based injector. The treatment demonstrated efficacy with minimal adverse effects, suggesting its potential for scar treatment. The clinical efficacy was supported by histological evidence obtained from cadaver skin, demonstrating an even distribution of injected particles in all layers of the dermis. In conclusion, we suggest that novel needle-free injectors offer advantages in precision and reduce patient discomfort, contributing to scar improvement and skin rejuvenation. Further comprehensive studies are warranted to substantiate these findings and ascertain the efficacy of this approach in scar treatment on a larger scale.