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Poly L-lactic acid (PLLA) fillers stimulate collagen synthesis by activating various immune cells and fibroblasts. Piezo1, an ion channel, responds to mechanical stimuli, including changes in extracellular matrix stiffness, by mediating Ca2+ influx. Given that elevated intracellular Ca2+ levels trigger signaling pathways associated with fibroblast proliferation, Piezo1 is a pivotal regulator of collagen synthesis and tissue fibrosis. The aim of the present study was to investigate the impact of PLLA on dermal collagen synthesis by activating Piezo1 in both an H2O2-induced cellular senescence model in vitro and aged animal skin in vivo. PLLA elevated intracellular Ca2+ levels in senescent fibroblasts, which was attenuated by the Piezo1 inhibitor GsMTx4. Furthermore, PLLA treatment increased the expression of phosphorylated ERK1/2 to total ERK1/2 (pERK1/2/ERK1/2) and phosphorylated AKT to total AKT (pAKT/AKT), indicating enhanced pathway activation. This was accompanied by upregulation of cell cycle-regulating proteins (CDK4 and cyclin D1), promoting the proliferation of senescent fibroblasts. Additionally, PLLA promoted the expression of phosphorylated mTOR/S6K1/4EBP1, TGF-β, and Collagen I/III in senescent fibroblasts, with GsMTx4 treatment mitigating these effects. In aged skin, PLLA treatment similarly upregulated the expression of pERK1/2/ERK1/2, pAKT/AKT, CDK4, cyclin D1, mTOR/S6K1/4EBP1, TGF-β, and Collagen I/III. In summary, our findings suggest Piezo1′s involvement in PLLA-induced collagen synthesis, mediated by heightened activation of cell proliferation signaling pathways such as pERK1/2/ERK1/2, pAKT/AKT, and phosphorylated mTOR/S6K1/4EBP1, underscoring the therapeutic potential of PLLA in tissue regeneration. [ABSTRACT FROM AUTHOR]

Background: Hyaluronic acid filler injection is commonly administered to correct temple hollowness, typically through deep temporal injection. Since the vascular distribution at the injection site can be diverse, studies on avoiding damage to the corresponding blood vessels are needed. Aims: To assess the commonly used hyaluronic acid filler injection site in the temple region, 1cm lateral and 1 cm above from the end of eyebrow, using a Doppler ultrasound to detect any anatomic variations in the blood vessels. Patients/Methods: Thirty patients (60 temples, right and left) were examined using Doppler ultrasonography. An 8‐17 MHz ultrasound probe was used to discriminate between the anatomic layers of the temple. Blood vessels found in each anatomical layer were subsequently investigated. Results: Among the 30 patients included in this study, we found temporal region arteries 1 cm above and 1 cm lateral to the distal end of the eyebrow in 9 patients; However, no arteries were detected in the temples of 21 patients. The presence or absence of arteries was bilateral in all patients. Conclusions: The anatomical layers with blood vessels varied among patients. The variability could give rise to complications. Possible anatomic variations at the temple should be carefully identified using pre‐injection ultrasonography, and harming blood vessels should be avoided while injecting hyaluronic acid filler for temple augmentation. [ABSTRACT FROM AUTHOR]

Background: Deviated noses and asymmetric nostrils can be corrected using corrective rhinoplasty. However, after proper correction, adjacent facial mimetic muscles can cause recurrence of asymmetry because of preoperative habits. Objectives: We performed this study to investigate the effects on botulinum toxin on the prevention of recurrence of asymmetry after corrective rhinoplasty. Methods: From January 2016 to December 2019, 60 patients underwent corrective rhinoplasty and 30 received botulinum toxin type A injection (Botulax; Hugel Co.) at the depressor septi nasi and levator labii superioris alaeque nasi muscles, bilaterally. Vertical and horizontal deviations were compared preoperatively and postoperatively. Results: Postoperative vertical deviation was 0.20° ± 0.65° in the botulinum toxin–injected group and 1.20° ± 0.53° in the control group (P < 0.0001). Horizontal deviation was 0.80° ± 0.52° in the botulinum toxin–injected group and 2.18° ± 0.42° in the control group (P < 0.005). Differences between preoperative and postoperative vertical deviations at 6 months were 2.30° ± 0.03° in patients who received botulinum toxin injection and 1.10° ± 0.22° in controls (P < 0.005). Conclusions: Botulinum toxin effectively restricted the paranasal muscles without any significant adverse events. We recommend injecting botulinum toxin after corrective rhinoplasty to prevent recurrence of deviation by facial mimetic muscles. [ABSTRACT FROM AUTHOR]