Evaluation of the in vivo effects of various laser, light, or ultrasound modalities on human skin treated with a collagen and polymethylmethacrylate microsphere dermal filler product

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.

The Intrinsic Relation between the Hydrogel Structure and In Vivo Performance of Hyaluronic Acid Dermal Fillers: A Comparative Study of Four Typical Dermal Fillers

BACKGROUND

Hyaluronic acid dermal fillers are composed of cross-linked viscoelastic particles with high biocompatibility. The performance of the fillers is determined by the viscoelastic properties of particles and the connecting force between particles. However, the relationships among the properties of fillers, the interaction of the gels and the surrounding tissue are not clear enough.

METHOD

Four kinds of typical dermal filler were selected in this research to reveal the interaction between the gels and cells. A series of analytical tools was applied to characterize the structure and physicochemical properties of the gel, as well as observing their interaction with the surrounding tissues in vivo and discussing their internal mechanism.

RESULT

The large particles internal the gel and the high rheological properties endow the Restylane2 with excellent support. However, these large-size particles have a significant impact on the metabolism of the local tissue surrounding the gel. Juvéderm3 present gel integrity with the high cohesiveness and superior support. The rational matching of large and small particles provides the Juvéderm3 with supporting capacity and excellent biological performance. Ifresh is characterized by small-size particles, moderate cohesiveness, good integrity, lower viscoelasticity and the superior cellular activity located the surrounding tissues. Cryohyaluron has high cohesion and medium particle size and it is prominent in cell behaviors involving localized tissues. Specific macroporous structure in the gel may facilitate the nutrients delivering and removing the waste.

CONCLUSION

It's necessary to make the filler both sufficient support and biocompatibility through the rational matching of particle sizes and rheological properties. Gels with macroporous structured particle showed an advantage in this area by providing a space inside the particle.

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.

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.

Histologic Effects of Fractional Laser and Radiofrequency Devices on Hyaluronic Acid Filler

BACKGROUND

Hyaluronic acid fillers (HAFs) and energy-based devices are frequently used sequentially. However, the effect of using fractional devices directly over HAF is unclear.

OBJECTIVE

To evaluate histologic changes after fractional laser and radiofrequency (RF) therapies applied over preinjected HAF.

MATERIALS AND METHODS

Abdominoplasty skin samples were divided into 8 zones. Intradermal injections of HAF were performed to 7 zones with 1 zone as untreated control. Six of 7 HAF injected zones were then treated with the following devices: 1,540-, 1,550-, 1927-, and 10,600-nm fractional lasers, and fractional bipolar RF delivered through insulated and noninsulated microneedles. After treatment, biopsies were collected for H&E staining.

RESULTS

Histology revealed HAF in the mid to deep dermis. Treatment with 1,540-, 1,550-, 1927-, and 10,600-nm lasers did not result in any morphologic changes of HAF, although thermal changes from 1,540- and 1,550-nm lasers were in very close proximity to the filler. The RF devices demonstrated thermal damage of HAF along the microneedle tracks.

CONCLUSION

Hyaluronic acid filler is unaffected by fractional lasers in this model. Fractional RF devices, which produce deeper dermal penetrations, will cause thermal damage of HAF. Caution is advised in using microneedle RF over recently injected filler. Study limitations include use of nonfacial skin and lack of inflammatory response in an ex-vivo model.

Materials-Directed Differentiation of Mesenchymal Stem Cells for Tissue Engineering and Regeneration

Cell-based therapies are a promising alternative to grafts and organ transplantation for treating tissue loss or damage due to trauma, malfunction, or disease. Over the past two decades, mesenchymal stem cells (MSCs) have attracted much attention as a potential cell population for use in regenerative medicine. While the proliferative capacity and multilineage potential of MSCs provide an opportunity to generate clinically relevant numbers of transplantable cells, their use in tissue regenerative applications has met with relatively limited success to date apart from secreting paracrine-acting factors to modulate the defect microenvironment. Presently, there is significant effort to engineer the biophysical properties of biomaterials to direct MSC differentiation and further expand on the potential of MSCs in tissue engineering, regeneration, and repair. Biomaterials can dictate MSC differentiation by modulating features of the substrate including composition, mechanical properties, porosity, and topography. The purpose of this review is to highlight recent approaches for guiding MSC fate using biomaterials and provide a description of the underlying characteristics that promote differentiation toward a desired phenotype.