Prevention and treatment of skin aging

Potential of bone marrow mesenchymal stem cells in rejuvenation of the aged skin of rats

The aim of the present study was to evaluate the anti-aging effects of bone marrow-mesenchymal stem cells (BM-MSCs) in a D-galactose-induced skin aging rat model. Male Sprague Dawley rats were randomly divided into four groups (n=10/group) as follows: Normal control group; skin aging model group; MSC-treated group by subcutaneous multi-point injection. The skin aging model was established by a daily subcutaneous injection of 15% D-galactose (1,000 mg/kg) for 8 weeks. Rats in the MSC-treated groups were administered 3×10⁶/ml BM-MSCs/green fluorescent protein (GFP) for 4 weeks, administered once per week. Oxidative/antioxidative parameters were evaluated, and morphological and ultrastructure analyses were performed. Rats in the model group exhibited the typical changes of aging skin. Compared with the control group, rats in the model group had significantly increased malondialdehyde (MDA) content (P<0.01), and decreased serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities (P<0.05). MSC treatment markedly ameliorated aging-induced oxidative stress in the skin. Histologically, rats in the model group exhibited loosely arranged epidermal cell layers and disorganized collagen fibers. BM-MSC treatment significantly improved the histological abnormalities, which was similar to those in the control group. In addition, 7 days after the final cell transplantation, GFP-positive cells were observed by fluorescence microscopy to be distributed in the dermis. Injection of BM-MSCs significantly improved the D-galactose-induced histological abnormalities of the skin, by promoting an antioxidant response and ameliorating oxidative stress in aged skin. Thus, BM-MSCs may be beneficial in the rejuvenation of aged skin.

Ultraviolet Photobiology in Dermatology

The effects of ultraviolet radiation on human skin have been studied for years, and both its harmful and therapeutic effects are well known. Exposure to UV light can lead to sunburn, immunosuppression, skin aging, and carcinogenesis, and photoprotection is strongly advocated. However, when used under controlled conditions, UV radiation can also be helpful in the diagnosis and treatment of many skin conditions.

Comparative study of isolation, expansion and characterization of epithelial cells

BACKGROUND AIMS

The human epithelial cells (EPCs) have been identified as the essential element for the regeneration of skin construct for burns, wounds and various tissue engineer-based products.

METHODS

In this study, the isolation, expansion and characterization of EPCs from various sources such as juvenile foreskin (JSK), buccal mucosa (BM), penile skin (PS) and urothelium (UR) in serum-free and xeno-free EpiLife media were evaluated.

RESULTS

The growth kinetics study revealed that EPCs from JSK and BM had notably higher growth rates compared with the others. Overall, the EPCs from all sources retained basic morphological characteristics and the functional characteristics such as Pan Cytokeratin (AE1/AE3). In addition, the cryopreservation stability of EPCs was accessed for post-thaw viability and found to be greater than 80% at 1 year of storage, but demonstrated reduced cell recovery (51%) at the second year in fetal bovine serum-free cryopreservation media.

CONCLUSIONS

Our result suggests that the EPCs from four cell sources can be grown in feeder-free, serum-free and xeno-free systems using commercially available EpiLife medium without losing epithelial cell characteristics even after passage 4. However, its suitability for clinical application must be accessed by preclinical and clinical studies.

Bioactive properties and potentials cosmeceutical applications of phlorotannins isolated from brown seaweeds: A review

Currently, natural ingredients are becoming more attractive for the industries such as functional food, nutraceuticals, cosmeceutical and pharmaceutical industries as people starting to believe naturally occurring compounds are safer to humans than artificial compounds. Seaweeds are one of the most interesting organisms found in oceans around the earth, which are carrying great ecological importance and contribute to increase the biodiversity of ecosystems where they were originated and habitat. Within last few decades, discovery of secondary metabolites with biological activities from seaweeds has been significantly increased. Further, the unique secondary metabolites isolated from seaweeds including polysaccharides, carotenoids and polyphenols possess range of bioactive properties that make them potential ingredient for many industrial applications. Among those groups of compounds phlorotannins isolated from brown seaweeds have shown interesting bioactive properties including anti-cancer, anti-inflammation, anti-oxidant, anti-allergic, anti-wrinkling and hair growth promotion properties. Moreover, these properties associated with phlorotannins make them an ideal compounds to use as a functional ingredient in cosmeceutical products. Up to now no report has been reviewed about discuss properties of phlorotannins related to the cosmeceutical application. In the present review primary attention is given to the collect scientific data published about bioactive properties of brown algal phlorotannins related to the cosmeceutical industry.

Instrumental evaluation of anti-aging effects of cosmetic formulations containing palmitoyl peptides, Silybum marianum seed oil, vitamin E and other functional ingredients on aged human skin

Anti-aging cosmetics are widely used for improving signs of aged skin such as skin wrinkles, decreased elasticity, low dermal density and yellow skin tone. The present study evaluated the effects of cosmetic formulations, eye cream and facial cream, containing palmitoyl peptides, Silybum marianum (S. marianum) seed oil, vitamin E and other functional ingredients on the improvement of facial wrinkles, elasticity, dermal density and skin tone after 4 weeks period of application on aged human skin. Healthy volunteers (n=20) with aged skin were recruited to apply the test materials facially twice per day for 4 weeks. Skin wrinkles, elasticity, dermal density and skin tone were measured instrumentally for assessing the improvement of skin aging. All the measurements were conducted prior to the application of test materials and at 2 and 4 weeks of treatment. Crow's feet wrinkles were decreased 5.97% after 2 weeks of test material application and 14.07% after 4 weeks of application in comparison of pre-application. Skin elasticity was increased 6.81% after 2 weeks and 8.79% after 4 weeks. Dermal density was increased 16.74% after 2 weeks and 27.63% after 4 weeks. With the L* value indicating skin brightness and the a* value indicating erythema (redness), the results showed that brightness was increased 1.70% after 2 weeks and 2.14% after 4 weeks, and erythema was decreased 10.45% after 2 weeks and 22.39% after 4 weeks. Hence, the test materials appear to exert some degree of anti-aging effects on aged human skin. There were no abnormal skin responses from the participants during the trial period. We conclude that the facial and eye cream containing palmitoyl peptides and S. marianum seed oil, vitamin E and other ingredients have effects on the improvement of facial wrinkles, elasticity, dermal density and skin tone.

Needle-free jet injection of hyaluronic acid improves skin remodeling in a mouse model

PURPOSE

The purpose of this study was to improve methods of jet injection using a mouse model. We investigated the mechanism of action, efficacy, and safety of the pneumatic device using injection of hyaluronic acid (HA) solution into a mouse model.

METHODS

We evaluated the efficacy and safety of an INNOJECTOR™ pneumatic device that pneumatically accelerates a jet of HA solution under high pressure into the dermis of mouse skin. We examined the treatment effects using skin hybrid model jet dispersion experiments, photographic images, microscopy, and histological analyses.

RESULTS

Use of the INNOJECTOR™ successfully increased dermal thickness and collagen synthesis in our mouse model. Jet dispersion experiments were performed using agarose gels and a polyacrylamide gel model to understand the dependence of jet penetration on jet power. The mechanisms by which pneumatic injection using HA solution exerts its effects may involve increased dermal thickening, triggering of a wound healing process, and activation of vimentin and collagen synthesis.

CONCLUSIONS

Collagen synthesis and increased dermal thickening were successfully achieved in our mouse model using the INNOJECTOR™. Pneumatic injection of HA under high pressure provides a safe and effective method for improving the appearance of mouse skin. Our findings indicate that use of the INNOJECTOR™ may induce efficient collagen remodeling with subsequent marked dermal layer thickening by targeting vimentin.

Topical Products for the Aging Face

This article focuses on nonprescription home-use topical treatment technologies for the aging face and is intended to serve as a guide for the core cosmeceutical technologies currently used and to help educate and assist the selection of topical antiaging products by the professional staff and their patients. Antiaging topical treatments for patient home use should be nonirritating, compatible with the patient skin type, effective, and complementary to surgical and minimally invasive office procedures, and aesthetically elegant. New topical antiaging technologies, formulated as monotherapy or as combinations with well-known cosmeceuticals, should present adequate clinical studies to support their selection for use.

Mimicking the topography of the epidermal-dermal interface with elastomer substrates

In human skin the interface between the epidermis and dermis is not flat, but undulates. The dimensions of the undulations change as a function of age and disease. Epidermal stem cell clusters lie in specific locations relative to the undulations; however, whether their location affects their properties is unknown. To explore this, we developed a two-step protocol to create patterned substrates that mimic the topographical features of the human epidermal-dermal interface. Substrates with negative patterns were first fabricated by exposing a photocurable formulation to light, controlling the topographical features (such as diameter, height and center-to-center distance) by the photomask pattern dimensions and UV crosslinking time. The negative pattern was then translated to PDMS elastomer to fabricate substrates with 8 unique surface topographies on which primary human keratinocytes were cultured. We found that cells were patterned according to topography, and that separate cues determined the locations of stem cells, differentiated cells and proliferating cells. The biomimetic platform we have developed will be useful for probing the effect of topography on stem cell behaviour.

Broadband Direct UVA irradiance measurement for clear skies evaluated using a smartphone

UVA wavelengths (320-400 nm) have been implicated in recent studies to contribute to melanoma induction and skin photoaging in humans and damage to plants. The use of smartphones in UVA observations is a way to supplement measurements made by traditional radiometric and spectroradiometric technology. Although the smartphone image sensor is not capable of determining broadband UVA irradiances, these can be reconstructed from narrowband irradiances, which the smartphone, with narrowband and neutral density filters, can quantify with discrepancies not exceeding 5 %. Three models that reconstruct direct broadband clear sky UVA were developed from narrowband irradiances derived from smartphone image sensor pixel data with coefficients of determination of between 0.97 and 0.99. Reasonable accuracy and precision in determining the direct broadband UVA was maintained for observations made with solar zenith angles as high as 70°. The developed method has the potential to increase the uptake of the measurement of broadband UVA irradiances.

New insights into skin stem cell aging and cancer

Adult tissue homoeostasis requires continual replacement of cells that are lost due to normal turnover, injury and disease. However, aging is associated with an overall decline in tissue function and homoeostasis, suggesting that the normal regulatory processes that govern self-renewal and regeneration may become impaired with age. Tissue-specific SCs (stem cells) lie at the apex of organismal conservation and regeneration, ultimately being responsible for continued tissue maintenance. In many tissues, there are changes in SC numbers, or alteration of their growth properties during aging, often involving imbalances in tumour-suppressor- and oncogene-mediated pathways. Uncovering the molecular mechanisms leading to changes in SC function during aging will provide an essential tool to address tissue-specific age-related pathologies. In the present review, we summarize the age-related alterations found in different tissue SC populations, highlighting recently identified changes in aged HFSCs (hair-follicle SCs) in the skin.

Stem cells and aberrant signaling of molecular systems in skin aging

The skin is the body's largest organ and it is able to self-repair throughout an individual's life. With advanced age, skin is prone to degenerate in response to damage. Although cosmetic surgery has been widely adopted to rejuvinate skin, we are far from a clear understanding of the mechanisms responsible for skin aging. Recently, adult skin-resident stem/progenitor cells, growth arrest, senescence or apoptotic death and dysfunction caused by alterations in key signaling genes, such as Ras/Raf/MEK/ERK, PI3K/Akt-kinases, Wnt, p21 and p53, have been shown to play a vital role in skin regeneration. Simultaneously, enhanced telomere attrition, hormone exhaustion, oxidative stress, genetic events and ultraviolet radiation exposure that result in severe DNA damage, genomic instability and epigenetic mutations also contribute to skin aging. Therefore, cell replacement and targeting of the molecular systems found in skin hold great promise for controlling or even curing skin aging.

Evaluation of the cloudy sky solar UVA radiation exposures

The influence of cloud on the solar UVA (320-400 nm) exposures over five minute periods on a horizontal plane has been investigated. The first approach used cloud modification factors that were evaluated using the influence of clouds on the global solar exposures (310-2800 nm) and a model developed to apply these to the clear sky UVA exposures to allow calculation of the five minute UVA exposures for any cloud conditions. The second approach established a relationship between the UVA and the global solar exposures. The models were developed using the first six months of data in 2012 for SZA less than or equal to 70° and were applied and evaluated for the exposures in the second half of 2012. This comparison of the modelled exposures for all cloud conditions to the measured data provided an R(2) of 0.8 for the cloud modification model, compared to an R(2) of 0.7 for the UVA/global model. The cloud modification model provided 73% of the five minute exposures within 20% of the measured UVA exposures. This was improved to 89% of the exposures within 20% of the measured UVA exposures for the cases of cloud with the sun not obscured.

Skin health in older age

As people age, their skin undergoes changes which result in reduced elasticity, increased fragility and an altered immune response; in essence it becomes frail. As life expectancy is increasing the health of older skin is becoming a progressively more important facet of overall care. In addition to the consequences of ageing for otherwise healthy skin, the relative incidence of some dermatological conditions is age-dependent. In particular, xerosis (dry skin), cutaneous malignancies and skin injuries are more common in older people. In this review we describe the functional consequences of skin ageing and discuss the current evidence on how skin health may be maintained and dermatological conditions prevented in an ageing population. The future of dermatological health-care provision in the older population relies on the development of coordinated pathways of care, which start from a young age. Better quality research coordinated by the establishment of institutions dealing with skin health and ageing would be a method of addressing these needs.

Decreased proliferative capacity of aged dermal fibroblasts in a three dimensional matrix is associated with reduced IGF1R expression and activation

Skin aging results in increased susceptibility to injury and impaired wound healing. Proliferation of fibroblasts is reduced in aged dermis, which contributes to delays in wound closure. Age-associated differences are regulated, in part, by local or systemic factors such as the IGF-1/IGF1R system. The aim of this study was to determine if expression and activation of IGF1R in aged human dermal fibroblasts, when compared to young fibroblasts, is associated with altered proliferative capacity in a 3D collagen matrix that better simulates the dermal extracellular matrix in vivo. The proliferation of young and aged human dermal fibroblasts in 3D collagen and its association with baseline levels of IGF1R expression were measured. The effect of stimulation and inhibition of Erk phosphorylation on the proliferative capacity of fibroblasts in a 3D collagen matrix was defined. Our results show that proliferation and Erk phosphorylation is reduced in aged dermal fibroblasts relative to young fibroblasts. Activation of Erk phosphorylation in aged fibroblasts is associated with a significant increase in fibroblast proliferation in 3D collagen.

The development of hyperbaric oxygen therapy for skin rejuvenation and treatment of photoaging

Hyperbaric oxygen therapy (HBOT), a therapy that have patients breath in pure oxygen in a pressurized chamber, has been long used as a treatment for conditions such as decompression sickness and carbon monoxide poisoning. Oxygen recently has been found to be an important component in skin rejuvenation, treatment of photoaging skin, and improvement in skin complexions. The interest in the use of HBOT for this purpose is continually growing and becoming more widespread. In addition to aging and genetic makeup, chronic UV radiation due to everyday exposure, especially UV-B, can greatly increase the rate of wrinkle formation through increasing skin angiogenesis and degradation of extracellular matrix molecules. The use of HBOT and hyperoxia conditions has been found to attenuate the formation of wrinkles from UV irradiation. It accomplishes the task by possibly inhibiting various processes and pathways involved such as the HIF1-α, VEGF, neutrophil infiltrations, and MMP-2 & MMP-9, which are directly involved with promoting skin angiogenesis in its active state. There are currently medical aesthetic clinics that are using oxygen therapy under high pressure applied directly to skin to reduce visible wrinkles but this procedure is not widespread yet due to more research that needs to be done on this topic. However, this treatment for wrinkles is definitely growing due to recent studies done showing the effectiveness of oxygen therapy on wrinkles. This review article will explore and summarize researches done on possible mechanisms dealing with the use of oxygen therapy for reduction of UVB-caused wrinkles, its side effects, and its possible future improvement and use in medicine.

Clinical and biometrological efficacy of a hyaluronic acid-based mesotherapy product: a randomised controlled study

Data demonstrating the efficacy of hyaluronic acid (HA)-based mesotherapy for skin rejuvenation are scarce. The aim of the study is to assess the efficacy of non-reticulated HA-based mesotherapy on skin elasticity and complexion radiance. 55 women with cutaneous ageing signs included in the Full Analysis Set (FAS) population blindly received intradermal micro-injections (50 × 0.02 mL) of non-cross-linked HA filler with mannitol (Glytone 1, HA concentration: 14 mg/g) in one cheek and saline physiological solution in the other according to hemifacial randomisation in 3 monthly sessions. Elasticity (E1 and E2 stiffness parameters) and dermis thickness were measured by cutometry and 20 MHz echography, before (D0) treatment and 1 (1M) and 3 months (3M) after the last injection. A trained panel blindly scored skin complexion radiance from standardised and calibrated photographs, using 100 mm analogue scales. In the FAS population, only HA filler significantly decreased E1 at 1M (−10.9 %, p = 0.026) and 3M (−10.5 %, p = 0.035) compared with D0; its effect versus the control tended to be more persistent, with a difference between treatments at 3M close to significance (p = 0.063). E2 also decreased at 1M (−8.2 %, p = 0.027 in the per protocol population, n = 53) and 3M after HA-treatment only. Dermis thickness significantly increased after HA-treatment at 1M (+3.4 %, p = 0.028) and 3M (+4 %, p = 0.008), and after control-treatment at 1M only (+2.5 %, p = 0.015). The HA filler significantly improved complexion radiance at 3M compared with the control (p = 0.012) and for 51 % of subjects, their skin status. Non-reticulated HA-based mesotherapy significantly and sustainably improves skin elasticity and complexion radiance.

Antiphotoaging effects of light-emitting diode irradiation on narrow-band ultraviolet B-exposed cultured human skin cells

BACKGROUND

Antiaging effects of light-emitting diodes (LEDs) have been clinically demonstrated using one or two wavelengths. The mechanism is unclear.

OBJECTIVE

To examine direct and indirect photobiomodulation effects of LEDs on narrow-band ultraviolet B (NB-UVB)-induced photoaging using seven different wavelengths alone or in combination.

MATERIALS AND METHODS

Four LED wavelengths were chosen based on type I collagen and metalloproteinase (MMP)-1 expression. NB-UVB-irradiated fibroblasts or keratinocytes were irradiated using these four wavelengths. The expression of collagen and MMP-1 in fibroblasts with or without conditioned medium from LED-irradiated keratinocytes and the expression of proinflammatory cytokines in the LED-irradiated keratinocytes were examined.

RESULTS

Irradiation with four wavelengths (630, 660, 830, and 850 nm) significantly increased the number of viable fibroblasts. These four wavelengths also increased type I collagen expression, particularly four combinations (630/830, 660/850, 630/850, and 660/830 nm). The fibroblasts cultured with the keratinocyte conditioned medium, particularly with a combination of 630/850 or 660/830 nm, increased collagen levels. Low tumor necrosis factor alpha (TNF-α) and high transforming growth factor beta 1 (TGF-β1) expression was detected in the LED-irradiated keratinocytes.

CONCLUSION

The combination of 630/850- or 660/830-nm irradiation led to better direct and indirect antiphotoaging outcomes than single LED wavelengths in NB-UVB-irradiated cultured normal human skin cells.

Royal jelly increases collagen production in rat skin after ovariectomy

Royal jelly (RJ) is a honeybee product that contains proteins, carbohydrates, fats, free amino acids, vitamins, and minerals. RJ has been reported to have antitumor, antibacterial, and wound-healing activities. We previously reported that RJ enhanced the migration of human dermal fibroblasts and altered the levels of cholesterol and sphinganine in an in vitro wound-healing model in addition to regulating skin photoaging following exposure to ultraviolet-B radiation. We established an animal model of skin aging in the context of estrogen deficiency and assessed the antiaging effects of RJ on skin. To establish an in vivo model of skin aging, bilateral ovariectomies were performed in 12-week-old virgin female Sprague-Dawley rats. Induction of osteoporosis was confirmed through two-dimensional images of the trabecular bone in the left femoral necks using microcomputed tomography. The protective effects of RJ ovariectomy-induced skin aging were examined by determining the protein expression of type I procollagen and matrix metalloproteinase (MMP)-1. The collagen content and epidermal thickness of skin tissue were measured by staining techniques. There was a significant difference in weight between sham-operated and ovariectomized groups. Food efficiency ratio did not differ significantly among the groups. The level of procollagen type I protein was increased in the dorsal skin of ovariectomized rats fed with a dietary supplement containing 1% RJ extract, but the level of MMP-1 was not altered. In particular, the amount of collagen recovered was close to the normal level. RJ may protect against skin aging by enhancing collagen production in rats with ovariectomy-induced estrogen deficiency.

Topically applied KTTKS: a review

Skin ageing is an irreversible process that is caused by both intrinsic and extrinsic factors. The possibility of arresting or delaying skin ageing represents a large research area and has a big potential in the cosmetics sector. Recently, the polypeptide lysine-threonine-threonine-lysine-serine (KTTKS) has attracted a lot of attention and it features in numerous up-market cosmetic products where it has become erroneously associated with the term 'pentapeptide'. In this study, we review in detail KTTKS and its major derivatives, in terms of the limited information in the literature and an appraisal of its physicochemical and theoretical skin permeation properties. There appears to be a sound in vitro basis for its action on fibroblasts due to its stimulatory effect on extracellular matrix synthesis, where the stimulatory effect of KTTKS is specific to collagen types I and III and fibronectin expression. However, there is a surprising absence of in vitro skin penetration data in the literature, and there are relatively few clinical studies using these materials.

Effect of aging on cellular mechanotransduction

Aging is becoming a critical heath care issue and a burgeoning economic burden on society. Mechanotransduction is the ability of the cell to sense, process, and respond to mechanical stimuli and is an important regulator of physiologic function that has been found to play a role in regulating gene expression, protein synthesis, cell differentiation, tissue growth, and most recently, the pathophysiology of disease. Here we will review some of the recent findings of this field and attempt, where possible, to present changes in mechanotransduction that are associated with the aging process in several selected physiological systems, including musculoskeletal, cardiovascular, neuronal, respiratory systems and skin.

The elderly as a sensitive population in environmental exposures: making the case

The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.

Recent advances on skin-resident stem/progenitor cell functions in skin regeneration, aging and cancers and novel anti-aging and cancer therapies

Recent advances in skin-resident adult stem/progenitor cell research have revealed that these immature and regenerative cells with a high longevity provide critical functions in maintaining skin homeostasis and repair after severe injuries along the lifespan of individuals. The establishment of the functional properties of distinct adult stem/progenitor cells found in skin epidermis and hair follicles and extrinsic signals from their niches, which are deregulated during their aging and malignant transformation, has significantly improved our understanding on the etiopathogenesis of diverse human skin disorders and cancers. Particularly, enhanced ultraviolet radiation exposure, inflammation and oxidative stress and telomere attrition during chronological aging may induce severe DNA damages and genomic instability in the skin-resident stem/progenitor cells and their progenies. These molecular events may result in the alterations in key signalling components controlling their self-renewal and/or regenerative capacities as well as the activation of tumour suppressor gene products that trigger their growth arrest and senescence or apoptotic death. The progressive decline in the regenerative functions and/or number of skin-resident adult stem/progenitor cells may cause diverse skin diseases with advancing age. Moreover, the photoaging, telomerase re-activation and occurrence of different oncogenic events in skin-resident adult stem/progenitor cells may also culminate in their malignant transformation into cancer stem/progenitor cells and skin cancer initiation and progression. Therefore, the anti-inflammatory and anti-oxidant treatments and stem cell-replacement and gene therapies as well as the molecular targeting of their malignant counterpart, skin cancer-initiating cells offer great promise to treat diverse skin disorders and cancers.

Profilometric and morphometric response of murine skin to cosmeceutical agents

OBJECTIVE

To investigate whether topical antiaging compounds can reduce wrinkle depth as noted at replica profilometry with comparable changes in histologic findings in hairless mice.

METHODS

Commercial retinoic acid cream, a peptide lotion, and a soy cream were applied to the dorsal skin for 4 weeks. Silicone-negative replicas of treated and untreated skin surface were photographed and evaluated for traditional features of surface roughness. Skin samples were processed using histomorphometry and immunohistochemistry of proliferating cell nuclear antigen. Quantitative light microscopic data were acquired for estimating replication of epidermal keratinocytes, epidermal thickness, and depth of dermal collagen bundles.

RESULTS

Data were analyzed by comparing means with 1-way analysis of variance, and significant changes in all measurements were noted. Augmented keratinocyte proliferation and thickening of viable epidermis were observed with all 3 compounds, although a greater effect was found in the retinoic acid and peptide treatment groups. A similar trend was noted with respect to widening of the collagen layer. Epidermal surface roughness manifested maximum smoothing after treatment with the peptide compound.

CONCLUSION

The pronounced effects noted with all 3 compounds indicate that topical agents other than retinoic acid may have comparative stimulating effects on the skin in nonirradiated mice.

Novel effects of diosgenin on skin aging

Extracts of Dioscorea coomposita or Dioscorea villosa are consumed as supplemental health foods at the time of climacteric. The extracts contain large amounts of the plant steroid, diosgenin. Here, we studied the safety and efficacy of diosgenin against skin aging at the time of climacteric. In vitro, diosgenin enhanced DNA synthesis in a human 3D skin equivalent model, and increased bromodeoxyuridine uptake and intracellular cAMP level in adult human keratinocytes. The increase of bromodeoxyuridine uptake by diosgenin was blocked by an adenylate cyclase inhibitor, but not by antisense oligonucleotides against estrogen receptor alpha, estrogen receptor beta or an orphan G-protein-coupled receptor, GPR30, indicating the involvement of cAMP but not estrogen receptor alpha, estrogen receptor beta or GPR30. In vivo, administration of diosgenin improved the epidermal thickness in the ovariectomized mice, a climacteric model, without altering the degree of fat accumulation. In order to examine the safety of diosgenin, diosgenin and 17beta-estradiol were administered to breast cancer-burdened mice. The results revealed that while 17beta-estradiol accelerated the tumor growth, diosgenin did not show this effect. Our finding, a restoration of keratinocyte proliferation in aged skin, suggests that diosgenin may have potential as a safe health food for climacteric.

From the rarest to the most common: insights from progeroid syndromes into skin cancer and aging

Despite their rarity, diseases of premature aging, or "progeroid" syndromes, have provided important insights into basic mechanisms that may underlie cancer and normal aging. In this review, we highlight these recent developments in Hutchinson-Gilford progeria syndrome (HGPS), Werner syndrome, Bloom syndrome, Cockayne syndrome, trichothiodystrophy, ataxia-telangiectasia, Rothmund-Thomson syndrome, and xeroderma pigmentosum. Though they are caused by different mutations in various genes and often result in quite disparate phenotypes, deciphering the molecular bases of these conditions has served to highlight their underlying basic similarities. Studies of progeroid syndromes, particularly HGPS, the most dramatic form of premature aging, have contributed to our knowledge of fundamental processes of importance to skin biology, including DNA transcription, replication, and repair, genome instability, cellular senescence, and stem-cell differentiation.

Recent insights into the molecular mechanisms involved in aging and the malignant transformation of adult stem/progenitor cells and their therapeutic implications

Recent advancements in tissue-resident adult stem/progenitor cell research have revealed that enhanced telomere attrition, oxidative stress, ultraviolet radiation exposure and oncogenic events leading to severe DNA damages and genomic instability may occur in these immature and regenerative cells during chronological aging. Particularly, the alterations in key signaling components controlling their self-renewal capacity and an up-regulation of tumor suppressor gene products such as p16(INK4A), p19(ARF), ataxia-telangiectasia mutated (ATM) kinase, p53 and/or the forkhead box O (FOXOs) family of transcription factors may result in their dysfunctions, growth arrest and senescence or apoptotic death during the aging process. These molecular events may culminate in a progressive decline in the regenerative functions and the number of tissue-resident adult stem/progenitor cells, and age-related disease development. Conversely, the telomerase re-activation and accumulation of numerous genetic and/or epigenetic alterations in adult stem/progenitor cells with advancing age may result in their immortalization and malignant transformation into highly leukemic or tumorigenic cancer-initiating cells and cancer initiation. Therefore, the cell-replacement and gene therapies and molecular targeting of aged and dysfunctional adult stem/progenitor cells including their malignant counterpart, cancer-initiating cells, hold great promise for treating and even curing diverse devastating human diseases. These diseases include premature aging diseases, hematopoietic, cardiovascular, musculoskeletal, pulmonary, ocular, urogenital, neurodegenerative and skin disorders and aggressive and recurrent cancers.

Survey on skin aging status and related influential factors in Southeast China

OBJECTIVE

To investigate cutaneous aging patterns of residents in Hangzhou, Zhejiang, China, and their contributing factors.

METHODS

Eight hundred and forty-eight Hangzhou residents received the survey between March 2004 and September 2004.

RESULTS

Facial wrinkling first occurred at 21 years of age and skin elasticity began to lose at 22 years of age. In middle-aged and old people, facial wrinkling and looseness escalated with the increase of ultraviolet (UV)-exposure time, indicating the accelerating effect of a higher accumulative dose of UV radiation on skin aging. Only Fitzpatrick types II, III and IV were found in the skin phototypes of residents in Hangzhou area, and Fitzpatrick type II seemed to be much more subject to severe wrinkling, elasticity destruction and skin tumors than types III and IV. The oily skin was more protected against wrinkling and facial looseness than dry skin. However, as to concomitant cutaneous diseases, no difference was found among different skin types.

CONCLUSION

Age, solar-exposure time, Fitzpatrick type and skin type are the associated forces in promoting skin aging, and emotional factor seems to be another independent risk factor. The age of 49 years and 2 h/d of solar-exposure time seem to be the turning points responsible for dramatic changes of cutaneous appearance in the process of skin aging in Southeast China.

Human skin stem cells and the ageing process

In healthy individuals, skin integrity is maintained by epidermal stem cells which self-renew and generate daughter cells that undergo terminal differentiation. Despite accumulation of senescence markers in aged skin, epidermal stem cells are maintained at normal levels throughout life. Therefore, skin ageing is induced by impaired stem cell mobilisation or reduced number of stem cells able to respond to proliferative signals. In the skin, existence of several distinct stem cell populations has been reported. Genetic labelling studies detected multipotent stem cells of the hair follicle bulge to support regeneration of hair follicles but not been responsible for maintaining interfollicular epidermis, which exhibits a distinct stem cell population. Hair follicle epithelial stem cells have at least a dual function: hair follicle remodelling in daily life and epidermal regeneration whenever skin integrity is severely compromised, e.g. after burns. Bulge cells, the first adult stem cells of the hair follicle been identified, are capable of forming hair follicles, interfollicular epidermis and sebaceous glands. In addition, -- at least in murine hair follicles -- they can also give rise to non-epithelial cells, indicating a lineage-independent pluripotent character. Multipotent cells (skin-derived precursor cells) are present in human dermis; dermal stem cells represent 0.3% among human dermal foreskin fibroblasts. A resident pool of progenitor cells exists within the sebaceous gland, which is able to differentiate into both sebocytes and interfollicular epidermis. The self-renewal and multi-lineage differentiation of skin stem cells make these cells attractive for ageing process studies but also for regenerative medicine, tissue repair, gene therapy and cell-based therapy with autologous adult stem cells not only in dermatology. In addition, they provide in vitro models to study epidermal lineage selection and its role in the ageing process.