Hallmarks of Skin Aging: Update

Aging-Associated Mitochondrial Decline Accelerates Skin Aging and Obesity

Skin tissue, which consists of epidermal, dermal, and hypodermal cells, plays an important role in biological defense and physical appearance. External and internal stresses occurring with aging disrupt skin homeostasis, promoting the development of phenotypes associated with aging. Although many studies of skin aging focus on the dermis, potential epidermal changes have largely remained uncharacterized. In this study, we demonstrate that epidermal cells do not exhibit cellular senescence phenotypes with aging but instead show age-related decreases in mitochondrial number. We also found that mice lacking TFAM in epidermal cells exhibit delayed hair regrowth and impaired wound healing by middle age, resembling changes seen in skin of aged mice. Furthermore, middle-aged epidermis-specific TFAM-deficient mice exhibited obesity, suggesting that impaired fatty acid metabolism in epidermal cells resulting from mitochondrial decline may lead to obesity. These findings overall suggest that mitochondrial decline occurs as a primary event in epidermal aging and that antiaging strategies to enhance activity or number of epidermal mitochondria could antagonize both skin-aging phenotypes and age-related metabolic disease.

Telomeres in skin aging

Skin aging is influenced by both intrinsic and extrinsic factors. The gradual manifestation of changes in telomere length and telomerase activity, as crucial indicators of aging, elucidates the underlying mechanism of skin aging. This review aims to comprehensively analyze the association between telomeres and aging, along with their impact on skin biological function. Firstly, we summarize the structure and function of telomeres and their role in cell division. Subsequently, we discuss the mechanisms through which telomere regulation contributes to aging processes while analyzing its involvement in skin aging by elaborating on biological markers. Furthermore, this paper presents a summary of recent research progress that reveals the correlation between telomere length and skin aging as well as model building methods; it also proposes telomere length as a potential indicator for predicting skin aging. Finally, anti-aging strategies based on telomere protection are discussed including drug therapy and lifestyle adjustments. This paper provides a systematic overview of the role played by telomeres in the field of skin aging for the first time, offering new perspectives and ideas for future prevention and treatment.

A nanochitin-drived natural biological adhesive with high cohesive for wound healing

The weak cohesive strength of tissue adhesives hinders their practical applications. To overcome this challenge, we develop a green bio-adhesive that balances both cohesion and adhesion, drawing inspiration from the natural adhesion mechanisms of mussels. This bio-adhesive, referred to as OTS, was ingeniously crafted through the co-assembly of multi-surface-charged chitin nanofibers (OAChN) and tannic acid (TA), integrated with silk fibroin (SF), resulting in a material with enhanced cohesive strength and robust adhesive properties. The adhesive achieved significant cohesion through hydrogen-bonded crosslinking among OAChN, SF, and TA, boasting a tensile strength of 24.53 KPa and allowing for 150 % elastic deformation. OTS adheres effectively to diverse complex surfaces, with adhesive strengths of 14.55 MPa underwater and 8.83 MPa in air, demonstrating excellent versatility. The biocompatibility and degradability of OTS were confirmed by a wound healing model in SD rats, showing no nanotoxicity and effectively promoting wound healing, rapid hemostasis, and sealing. This green adhesive strategy offers a novel approach to augmenting the cohesive strength of tissue adhesives suitable for complex conditions and has potential medical applications ranging from rapid hemostasis to wound healing enhancement.

Anti-ageing mechanism of topical bioactive ingredient composition on skin based on network pharmacology

OBJECTIVE

To elucidate the anti-ageing mechanism of the combination of eight ingredients on the skin from a multidimensional view of the skin.

METHODS

The target pathway mechanisms of composition to delay skin ageing were investigated by a network pharmacology approach and experimentally validated at three levels: epidermal, dermal, and tissue.

RESULTS

We identified 24 statistically significant skin ageing-related pathways, encompassing crucial processes such as epidermal barrier repair, dermal collagen and elastin production, inhibition of reactive oxygen species (ROS), as well as modulation of acetylcholine and acetylcholine receptor binding. Furthermore, our in vitro experimental findings exhibited the following outcomes: the composition promotes fibroblast proliferation and the expression of barrier-related genes in the epidermis; it also stimulated the expression of collagen I, collagen III, and elastic fibre while inhibiting ROS and β-Gal levels in HDF cells within the dermis. Additionally, Spilanthol in the Acmella oleracea extract contained in the composition demonstrated neuro-relaxing activity in Zebrafish embryo, suggesting its potential as an anti-wrinkle ingredient at the hypodermis level.

CONCLUSIONS

In vitro experiments validated the anti-ageing mechanism of composition at multiple skin levels. This framework can be extended to unravel the functional mechanisms of other clinically validated compositions, including traditional folk recipes utilized in cosmeceuticals.

Holistic investigation of the anti-wrinkle and repair efficacy of a facial cream enriched with C-xyloside

OBJECTIVE

To investigate the repairing and anti-wrinkle efficacy of the facial cream enriched with C-xyloside, aiming at comprehensively evaluating its skin anti- aging effect and clarify its potential mechanism of action.

METHODS

The repairing efficacy was studied on 3D epidermis skin model and the antiaging efficacy was studied on ex-vivo human skin. Two clinical studies were conducted with Chinese females. In the first study, 49 subjects aged between 30 and 50 with wrinkle concerns were recruited and instructed to apply the investigational cream containing C-xyloside for 8 weeks. Wrinkles attributes were assessed by dermatologist. Instrumental measurements on skin hydration, trans-epidermal water loss (TEWL), and skin elasticity were also conducted. In the second study, 30 subjects aged between 25 and 60 with self-declared sensitive skin and facial redness were recruited and instructed to apply the cream for 4 weeks. Biomarker analysis of the stratum corneum was conducted through facial tape strips.

RESULTS

The cream improved the histomorphology of the 3D epidermis skin model after SLS stimulation, and significantly increase the expression of LOR and FLG. On human skin, the cream improved the histopathology induced by UV, and significantly increased the protein content of COL I and COL III, collagen density and the number of Ki-67 positive cell of skin compared with model group (n = 3, p < 0.01). The results from the first clinical study demonstrate a significant increased the skin hydration and elasticity by 21.90%, 13.08% (R2) and 12.30% (R5), respectively (n = 49, p < 0.05), and the TEWL values decreased by 33.94% (n = 49, p < 0.05), after 8 weeks application of the cream. In addition, the scores for nasolabial folds, glabellar wrinkle, underneath eye wrinkles, crow's feet wrinkle and forehead wrinkle in the volunteers exhibited a significant reduction of 34.02%, 43.34%, 50.03%, 33.64% and 55.81% respectively (n = 49, p < 0.05). The (rCE)/(fCE) ratio of volunteers based on tape stripping significant increased after using the sample cream (n = 30, p < 0.05).

CONCLUSION

The cream containing C-xyloside showed improvement of skin wrinkles and enhancement of skin barrier function. These efficacies may be attributed to the fact that the sample cream can increase the expression of skin barrier related proteins LOR and FLG, promote the maturation of cornified envelope, enhance collagen I and III protein expression and stimulate skin cell proliferation, to provide sufficient evidence supporting its antiaging efficacy of skin.

Uncovering key mechanisms and intervention therapies in aging skin

Advancements in understanding skin aging mechanisms, which encompass both external and internal aging processes, have spurred the development of innovative treatments primarily aimed at improving cosmetic appearance. These findings offer the potential for the development of novel therapeutic strategies aimed at achieving long-term, non-therapy-dependent clinical benefits, including the reversal of aging and the mitigation of associated health conditions. Realizing this goal requires further research to establish the safety and efficacy of targeting aging-related skin changes, such as pigmentation, wrinkling, and collagen loss. Systematic investigation is needed to identify the most effective interventions and determine optimal anti-aging treatment strategies. These reviews highlight the features and possible mechanisms of skin aging, as well as the latest progress and future direction of skin aging research, to provide a theoretical basis for new practical anti-skin aging strategies.

The Characteristics and Inheriting Pattern of Skin Aging in Chinese Women: An Intergenerational Study of Mothers and Daughters

Introduction

The aging of the skin, which is affected by both external and internal causes, can reflect the external age and the internal health status. While the aging characteristics differ across ethnic groups, the specific changes in skin aging within the Chinese population have been underexplored. Moreover, investigating the similarity of aging skin characteristics between parent-offspring pairs remains uncharted territory. This study aims to fill these gaps by examining the skin aging features of Chinese women and assessing the similarity in aging skin characteristics between mother-daughter pairs.

Methods

A total of 40 mother-daughter pairs were recruited and analyzed. The perceived ages of the participants were evaluated, and their aging skin traits were systematically graded. Statistical methods were employed to discern the trends of the aging skin characteristics. By introducing a novel similarity parameter, we compared whether various skin aging characteristics have similar patterns between mothers and daughters.

Results

Our findings indicate that age 50 represents a pivotal point in skin aging. Beyond this age, the increase in rhytides and laxity scores accelerated noticeably, whereas the escalation in dyschromia scores became less marked. By introducing similar parameters between mother-daughter pairs and the radar map, we discovered that the skin aging characteristics are remarkably consistent between mother-daughter pairs.

Conclusion

Understanding the main aging skin characteristics of different age groups can allow caregivers to devise treatments for preventing skin aging in women of various ages. The mother's skin aging trend is also significant for the daughter's skin aging prevention.

Role of epigenetics in the regulation of skin aging and geroprotective intervention: A new sight

Multiple epigenetic factors play a regulatory role in maintaining the homeostasis of cutaneous components and are implicated in the aging process of the skin. They have been associated with the activation of the senescence program, which is the primary contributor to age-related decline in the skin. Senescent species drive a series of interconnected processes that impact the immediate surroundings, leading to structural changes, diminished functionality, and heightened vulnerability to infections. Geroprotective medicines that may restore the epigenetic balance represent valid therapeutic alliances against skin aging. Most of them are well-known Western medications such as metformin, nicotinamide adenine dinucleotide (NAD+), rapamycin, and histone deacetylase inhibitors, while others belong to Traditional Chinese Medicine (TCM) remedies for which the scientific literature provides limited information. With the help of the Geroprotectors.org database and a comprehensive analysis of the referenced literature, we have compiled data on compounds and formulae that have shown potential in preventing skin aging and have been identified as epigenetic modulators.

Dermatologic Manifestations of Mitochondrial Dysfunction: A Review of the Literature

Mitochondria are eukaryotic cellular organelles that function in energy metabolism, ROS production, and programmed cell death. Cutaneous epithelial and hair follicle dermal papilla cells are energy-rich cells that thereby may be affected by mitochondrial dysfunction and DNA mutation accumulation. In this review, we aimed to summarize the medical literature assessing dermatologic conditions and outcomes associated with mitochondrial dysfunction. A search of PubMed and Embase was performed with subsequent handsearching to retrieve additional relevant articles. Mitochondrial DNA (mtDNA) deletions, mutation accumulation, and damage are associated with phenotypic signs of cutaneous aging, hair loss, and impaired wound healing. In addition, several dermatologic conditions are associated with aberrant mitochondrial activity, such as systemic lupus erythematosus, psoriasis, vitiligo, and atopic dermatitis. Mouse model studies have better established causality between mitochondrial damage and dermatologic outcomes, with some depicting reversibility upon restoration of mitochondrial function. Mitochondrial function mediates a variety of dermatologic conditions, and mitochondrial components may be a promising target for therapeutic strategies.

Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners

In this narrative review, we sought to provide a comprehensive overview of the mechanisms underlying cutaneous senescence, framed by the twelve traditional hallmarks of aging. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. We also examined how topical interventions targeting these hallmarks can be integrated with conventional aesthetic medicine techniques to enhance skin rejuvenation. The potential of combining targeted topical therapies against the aging hallmarks with minimally invasive procedures represents a significant advancement in aesthetic medicine, offering personalized and effective strategies to combat skin aging. The reviewed evidence paves the way for future advancements and underscores the transformative potential of integrating scientifically validated interventions targeted against aging hallmarks into traditional aesthetic practices.