Promises and challenges of senolytics in skin regeneration, pathology and ageing

Poly-l-lactic acid microspheres delay aging of epidermal stem cells in rat skin

Objective

Injectable skin fillers offer a wider range of options for cutaneous anti-aging and facial rejuvenation. PLLA microspheres are increasingly favored as degradable and long-lasting fillers. The present study focused solely on the effect of PLLA on dermal collagen, without investigating its impact on the epidermis. In this study, we investigated the effects of PLLA microspheres on epidermal stem cells (EpiSCs).

Methods

Different concentrations of PLLA microspheres on epidermal stem cells (EpiSCs) in vitro through culture, and identification of primary rat EpiSCs. CCK-8 detection, apoptosis staining, flow cytometry, Transwell assay, wound healing assay, q-PCR analysis, and immunofluorescence staining were used to detect the effects of PLLA on EpiSCs. Furthermore, we observed the effect on the epidermis by injecting PLLA into the dermis of the rat skin in vivo.

Results

PLLA microspheres promote cell proliferation and migration while delaying cell senescence and maintaining its stemness. In vitro, Intradermal injection of PLLA microspheres in the rat back skin resulted in delayed aging, as evidenced by histological and immunohistochemical staining of the skin at 2, 4, and 12 weeks of follow-up.

Conclusion

This study showed the positive effects of PLLA on rat epidermis and EpiSCs, while providing novel insights into the anti-aging mechanism of PLLA.

Adipose Tissue in Cardiovascular Disease: From Basic Science to Clinical Translation

The perception of adipose tissue as a metabolically quiescent tissue, primarily responsible for lipid storage and energy balance (with some endocrine, thermogenic, and insulation functions), has changed. It is now accepted that adipose tissue is a crucial regulator of metabolic health, maintaining bidirectional communication with other organs including the cardiovascular system. Additionally, adipose tissue depots are functionally and morphologically heterogeneous, acting not only as sources of bioactive molecules that regulate the physiological functioning of the vasculature and myocardium but also as biosensors of the paracrine and endocrine signals arising from these tissues. In this way, adipose tissue undergoes phenotypic switching in response to vascular and/or myocardial signals (proinflammatory, profibrotic, prolipolytic), a process that novel imaging technologies are able to visualize and quantify with implications for clinical prognosis. Furthermore, a range of therapeutic modalities have emerged targeting adipose tissue metabolism and altering its secretome, potentially benefiting those at risk of cardiovascular disease.

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.

Senescence-associated alterations in the extracellular matrix: deciphering their role in the regulation of cellular function

The extracellular matrix (ECM) is a dynamic structural network that provides a physical scaffolding, as well as biochemical factors that maintain normal tissue homeostasis and thus its disruption is implicated in many pathological conditions. On the other hand, senescent cells express a particular secretory phenotype, affecting the composition and organization of the surrounding ECM and modulating their microenvironment. As accumulation of senescent cells may be linked to the manifestation of several age-related conditions, senescence-associated ECM alterations may serve as targets for novel anti-aging treatment modalities. Here, we will review characteristic changes in the ECM elicited by cellular senescence and we will discuss the complex interplay between ECM and senescent cells, in relation to normal aging and selected age-associated pathologies.

The meaning of adaptation in aging: insights from cellular senescence, epigenetic clocks and stem cell alterations

With recent rapid progress in research on aging, there is increasing evidence that many features commonly considered to be mechanisms or drivers of aging in fact represent adaptations. Here, we examine several such features, including cellular senescence, epigenetic aging and stem cell alterations. We draw a distinction between the causes and consequences of aging and define short-term consequences as 'responses' and long-term ones as 'adaptations'. We also discuss 'damaging adaptations', which despite having beneficial effects in the short term, lead to exacerbation of the initial insult and acceleration of aging. Features commonly recognized as 'basic mechanisms of the aging process' are critically examined for the possibility of their adaptation-driven emergence from processes such as cell competition and the wound-like features of the aging body. Finally, we speculate on the meaning of these interactions for the aging process and their relevance for the development of antiaging interventions.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

Oral Supplementation and Systemic Drugs for Skin Aging: A Narrative Review

Skin aging is influenced by intrinsic and extrinsic factors and involves multiple pathogenic mechanisms. The most widely used treatments are topical products and minimally invasive procedures. Evidence on the benefits of systemic therapy is limited for several reasons: Reliance on mostly small and predominantly female samples, short study durations, methodologic heterogeneity, and a lack of consensus on which outcome measures are clinically relevant. Furthermore, systemic drugs and oral supplements are not without adverse effects. Oral hydrolyzed collagen and oral hyaluronic acid are well tolerated, and numerous clinical trials show they can mitigate some signs of skin aging. Low-dose oral isotretinoin is another option, but it has a higher risk of adverse effects. Evidence is lacking on the effects of the many dietary supplements on offer, such as vitamins, flavonoids, plant extracts, and trace elements. The future of skin aging management would appear to lie in the use of senolytic and senomorphic agents targeting senescent cells in the skin.

Efficacy and Safety of Topical or Oral Hydrolyzed Collagen in Women with Dermatoporosis: A Randomized, Double-Blind, Factorial Design Study

BACKGROUND

Dermatoporosis defines the progressive chronic cutaneous insufficiency syndrome. Stage I is characterized by cutaneous atrophy, senile purpura, and stellate pseudoscars.

OBJECTIVE

To assess clinical, histologic, quality of life, and biophysical effects of oral and/or topical hydrolyzed collagen (HC) on forearm skin of postmenopausal women with Dermatoporosis stage I.

METHODS

Double-blind randomized placebo-controlled factorial design study. Two groups of menopausal women with stage I dermatoporosis on forearms were randomized to oral HC 5 g/day or matching placebo, and also to topical serum 2.5% HC or matching placebo once a day, for 6 months.

RESULTS

A total of 56 women, age range 60-93 years (mean 69.5 ± 7.3 years) were included. Comparing data from baseline and after 6 months, no significant difference was observed for each intervention nor their comparison, for all efficacy parameters: clinical and quality of life scores, dermal elasticity, thickness and echogenicity, and histologic and immunohistochemical markers (p > 0.1).

LIMITATIONS

Larger studies to confirm our findings are warranted.

CONCLUSIONS

In menopausal women with stage I dermatoporosis, oral or topical collagen peptides used alone or in combination do not have benefits on forearm skin after 6 months of intervention, and therefore should not be used routinely in this population. CONSORT flow chart.

[Translated article] Oral Supplementation and Systemic Drugs for Skin Aging: A Narrative Review

Skin aging is influenced by intrinsic and extrinsic factors and involves multiple pathogenic mechanisms. The most widely used treatments are topical products and minimally invasive procedures. Evidence on the benefits of systemic therapy is limited for several reasons: reliance on mostly small and predominantly female samples, short study durations, methodologic heterogeneity, and a lack of consensus on which outcome measures are clinically relevant. Furthermore, systemic drugs and oral supplements are not without adverse effects. Oral hydrolyzed collagen and oral hyaluronic acid are well tolerated, and numerous clinical trials show they can mitigate some signs of skin aging. Low-dose oral isotretinoin is another option, but it has a higher risk of adverse effects. Evidence is lacking on the effects of the many dietary supplements on offer, such as vitamins, flavonoids, plant extracts, and trace elements. The future of skin aging management would appear to lie in the use of senolytic and senomorphic agents targeting senescent cells in the skin.

Role of Senescent Cells in Cutaneous Wound Healing

Cellular senescence has gained increasing attention in the field of aging research. Senescent cells have been implicated in biological aging processes, tumorigenesis, development, and wound repair amongst other processes and pathologies. Recent findings reveal that senescent cells can both promote and inhibit cutaneous wound healing processes. Relating senescent cells in acute and chronic wounds will help to clarify their role in wound healing processes and inform our understanding of senescent cell heterogeneity. To clarify this apparent contradiction and guide future research and therapeutic development, we will review the rapidly growing field of cellular senescence and its role in wound healing biology.

Targeting Cellular Senescence with Senotherapeutics: Development of New Approaches for Skin Care

SUMMARY

Aging of the skin is evidenced by increased wrinkles, age spots, dryness, and thinning with decreased elasticity. Extrinsic and intrinsic factors including UV, pollution, and inflammation lead to an increase in senescent cells (SnCs) in skin with age that contribute to these observed pathological changes. Cellular senescence is induced by multiple types of damage and stress and is characterized by the irreversible exit from the cell cycle with upregulation of cell cycle-dependent kinase inhibitors p16INK4a and p21CIP1. Most SnCs also developed an inflammatory senescence-associated secretory phenotype (SASP) that drives further pathology through paracrine effects on neighboring cells and endocrine effects on cells at a distance. Recently, compounds able to kill senescent cells specifically, termed senolytics, or suppress the SASP, termed senomorphics, have been developed that have the potential to improve skin aging as well as systemic aging in general. Here, we provide a summary of the evidence for a key role in cellular senescence in driving skin aging. In addition, the evidence for the potential application of senotherapeutics for skin treatments is presented. Overall, topical, and possibly oral senotherapeutic treatments have tremendous potential to eventually become a standard of care for skin aging and related skin disorders.

Metformina en el tratamiento de enfermedades dermatológicas: una revisión narrativa

Objetivo

Revisar y discutir la evidencia actual del uso de la metformina como herramienta terapéutica en enfermedades cutáneas.

Diseño

Artículo original. Investigación cualitativa. Revisión narrativa.

Emplazamiento

Aragón y Murcia, España.

Participantes

Médicos Internos Residentes de Dermatología Médico-Quirúrgica y Venereología y de Atención Primaria y Comunitaria.

Métodos

Se ha realizado una revisión narrativa utilizando la base de datos bibliográfica PubMed con fecha de búsqueda el 27 de enero de 2022.

Resultados

La metformina ha demostrado ser efectiva en el tratamiento de dermatosis inflamatorias tales como el acné, hidrosadenitis supurativa, psoriasis y dermatitis de contacto alérgica. También ha demostrado propiedades antitumorales frente al carcinoma basocelular, carcinoma espinocelular y melanoma. De forma adicional, se ha descrito efectos beneficiosos del tratamiento adyuvante con metformina en pacientes con carcinoma basocelular que reciben terapia fotodinámica. En pacientes con dermatosis relacionadas con endocrinopatías tales como el hirsutismo, la acantosis nigricans y los xantomas eruptivos, el tratamiento con metformina ha demostrado efectividad terapéutica. El tratamiento tópico con metformina ha demostrado ser eficaz en el tratamiento del melasma. Finalmente se ha propuesto como un fármaco con propiedades antienvejecimiento cutáneo y favorecedoras de la cicatrización. Para ninguna de las indicaciones previamente descritas se han objetivado efectos adversos graves.

Conclusiones

La metformina es un tratamiento efectivo y seguro en el esquema terapéutico de dermatosis inflamatorias, neoplasias cutáneas, dermatosis relacionadas con endocrinopatías, melasma, envejecimiento cutáneo y cicatrización.

Emerging cellular senescence-centric understanding of immunological aging and its potential modulation through dietary bioactive components

Immunological aging is strongly associated with the observable deleterious effects of human aging. Our understanding of the causes, effects, and therapeutics of aging immune cells has long been considered within the sole purview of immunosenescence. However, it is being progressively realized that immunosenescence may not be the only determinant of immunological aging. The cellular senescence-centric theory of aging proposes a more fundamental and specific role of immune cells in regulating senescent cell (SC) burden in aging tissues that has augmented the notion of senescence immunotherapy. Now, in addition, several emerging studies are suggesting that cellular senescence itself may be prevalent in aging immune cells, and that senescent immune cells exhibiting characteristic markers of cellular senescence, similar to non-leucocyte cells, could be among the key drivers of various facets of physiological aging. The present review integrates the current knowledge related to immunosenescence and cellular senescence in immune cells per se, and aims at providing a cohesive overview of these two phenomena and their significance in immunity and aging. We present evidence and rationalize that understanding the extent and impact of cellular senescence in immune cells vis-à-vis immunosenescence is necessary for truly comprehending the notion of an 'aged immune cell'. In addition, we also discuss the emerging significance of dietary factors such as phytochemicals, probiotic bacteria, fatty acids, and micronutrients as possible modulators of immunosenescence and cellular senescence. Evidence and opportunities related to nutritional bioactive components and immunological aging have been deliberated to augment potential nutrition-oriented immunotherapy during aging.