Genome-wide association studies in the Japanese population identified genetic loci and target gene associated with epidermal turnover

The epidermis is an essential organ for life by retaining water and as a protective barrier. The epidermis is maintained through metabolism, in which basal cells produced from epidermal stem cells differentiate into spinous cells, granular cells and corneocytes, and are finally shed from the epidermal surface. This is epidermal turnover, and with aging, there is a decline in epidermis function. Other factors that may affect epidermal turnover include ultraviolet damage and genetic factors. These genetic factors are of particular interest as little is known. Although recent skin-focused genome-wide association studies (GWAS) have been conducted, the genetic regions associated with epidermal turnover are almost uninvestigated. Therefore, we conducted a GWAS on epidermal turnover in the Japanese population, using the corneocyte area, which correlates to the rate of epidermal turnover, as an indicator. As a result, rs2278431 (p = 1.29 × 10-7 ) in 19q13.2 was associated with corneocyte size. Furthermore, eQTL analysis suggested that rs2278431 was related to the SPINT2 gene. In addition, SPINT2 knockdown studies using epidermal keratinocytes revealed that SPINT2 is involved in keratinocyte proliferation and in corneocyte size regulation in reconstructed epidermis. These results suggest that rs2278431 is involved in the expression of SPINT2 and affects epidermal turnover.

Melanin accumulation in dermal stem cells deteriorates their exosome-mediated skin basement membrane construction in solar lentigo

Solar lentigo (SL) is a hyperpigmented macule that occurs in sun-exposed areas and is characterized by the accumulation of melanin pigment in the epidermis. On the contrary, melanin-incorporated macrophages have also been identified in the dermis, which is thought to be caused by melanin transfer due to disruption of the basement membrane, but the detailed mechanism remains unclear. In this study, we analysed SL lesions by pathological methods and examined the mechanism of melanin accumulation in the dermis using cultured skin models in vitro. First, we observed a significant decrease in type IV collagen (COL4), a major component of the basement membrane, in SL lesions. The basement membrane is known to be formed by the interaction of keratinocytes and dermal cells. Therefore, we constructed skin models containing fibroblasts or dermal stem cells and examined their effects on basement membrane formation. The results showed a markedly enhanced production of COL4 mediated by dermal stem cell-derived exosomes. The analysis of melanin localization in the SL dermis revealed that CD163-positive macrophages and CD271-positive dermal stem cells both took up melanin pigment. Exosomes of dermal stem cells incorporating melanosomes were less effective in promoting COL4 expression. These findings suggest that while the promotion of COL4 production in keratinocytes by dermal stem cell-derived exosomes is important for maintaining basement membrane homeostasis, this mechanism is disrupted in SL lesions, leading to chronic melanin accumulation in the dermis.

Identification of mitochondrial genetic variants associated with human corneocyte size in Japanese women

Mitochondria have their own DNA (mtDNA). Genetic variants are likely to accumulate in mtDNA, and its base substitution rate is known to be very fast, 10-20 times faster than that of nuclear DNA. For this reason, mtSNPs (mitochondrial genome single nucleotide polymorphisms) are frequently detected in mtDNA. Several thousands of copies of mtDNA are considered to be present in a cell, and variants that have occurred in mtDNA are expected to markedly affect the intracellular energy production system and ROS (reactive oxygen species) kinetics. Therefore, recently, mtSNPs have come to be considered very important as a determinant of the individual constitution such as the life-span and disease susceptibility. In this study, we searched for mtSNPs that affect the individual corneocyte size using samples from 358 Japanese women. As a result, mtSNPs 10609C and 12406A were found to be significantly related to the corneocyte size in the outermost layer of the epidermis. There have been a large number of reports concerning the association between mtSNPs and individual constitution, but little evaluation of their relationships with epidermal properties has been made. The results of the present study first suggested that mtSNPs may affect the epidermal properties in Japanese women.

Analysis of the effect of daily stress on the skin and search for genetic loci involved in the perceived stress of an individual

Background

Stress may have various effects on our bodies. In particular, the skin may be readily influenced by stress. In addition, there are individual differences in the way we feel stress, suggesting the involvement of genetic factors in such individual differences.

Objectives

In this study, we analysed the influence of stress on skin condition and ageing involving Japanese females, and investigated single nucleotide polymorphisms (SNPs) that influence perceived stress of an individual.

Methods

We collected genotype data from 1200 Japanese females. At the same time, a questionnaire was conducted on the degree of stress that each subject feels on a daily basis and the current skin condition. We analysed the effects of stress on skin condition and searched for SNPs related to individual stress susceptibility by genome‐wide association studies.

Results

Our data suggested that stress influences skin condition and ageing, as previously reported. And, we found rs74548608 as a SNP that affects perceived stress of an individual. This SNP is located on the upstream of Patched‐1, which is a gene that functions as a sonic hedgehog receptor.

Conclusions

Our study has identified new genetic factors for perceived stress of an individual in the Japanese female. The SNP found in this study may be a candidate factor important for understanding the perceived stress of an individual of Japanese.

Enhanced Type I Collagen Synthesis in Fibroblasts by Dermal Stem/Progenitor Cell-Derived Exosomes

The self-duplication and differentiation of dermal stem cells are essential for the maintenance of dermal homeostasis. Fibroblasts are derived from dermal stem cells and produce components of connective tissue, such as collagen, which maintains the structure of the dermis. Cell-cell communication is required for the maintenance of tissue homeostasis, and the role of exosomes in this process has recently been attracting increasing attention. Dermal stem cells and fibroblasts have been suggested to communicate with each other in the dermis; however, the underlying mechanisms remain unclear. In the present study, we investigated communication between dermal stem/progenitor cells (DSPCs) and fibroblasts via exosomes. We collected exosomes from DSPCs and added them to a culture of fibroblasts. With the exosomes, COL1A1 mRNA expression was up-regulated and dependent on the Akt phosphorylation. Exosomes collected from fibroblasts did not show the significant up-regulation of COL1A1 mRNA expression. We then performed a proteomic analysis and detected 74 proteins specific to DSPC-derived exosomes, including ANP32B related to Akt phosphorylation. We added exosomes in which ANP32B was knocked down to a fibroblast culture and observed neither Akt phosphorylation nor enhanced type I collagen synthesis. Additionally, an immunohistochemical analysis of skin tissues revealed that ANP32B expression levels in CD271-positive dermal stem cells were lower in old subjects than in young subjects. These results suggest that DSPCs promote type I collagen synthesis in fibroblasts by secreting exosomes containing ANP32B, which may contribute to the maintenance of skin homeostasis; however, this function of DSPCs may decrease with aging.

Genome-wide association studies in Japanese women identified genetic loci associated with wrinkles and sagging

Wrinkles and sagging are caused by various factors, such as ultraviolet rays; however, recent findings demonstrated that some individuals are genetically predisposed to these phenotypes of skin aging. The contribution of single nucleotide polymorphisms (SNPs) to the development of wrinkles and sagging has been demonstrated in genome-wide association studies (GWAS). However, these findings were mainly obtained from European and Chinese populations. Limited information is currently available on the involvement of SNPs in the development of wrinkles and sagging in a Japanese population. Therefore, we herein performed GWAS on wrinkles at the outer corners of the eyes and nasolabial folds in 1041 Japanese women. The results obtained revealed that 5 SNPs (19p13.2: rs2303098 (p = 3.39×10^-8 ), rs56391955 (p = 3.39×10^-8 ), rs67560822 (p = 3.50×10^-8 ), rs889126 (p = 3.78×10^-8 ), rs57490083 (p = 3.99×10^-8 )) located within the COL5A3 gene associated with wrinkles at the outer corners of the eyes. Regarding nasolabial folds, 8q24.11 (rs4876369; p = 1.05×10^-7 , rs6980503; p = 1.25×10^-7 , rs61027543; p = 1.25×10^-7 , rs16889363; p = 1.38×10^-7 ) was suggested to be associated with RAD21 gene expression. These SNPs have not been reported in other populations, and were first found in Japanese women population. These SNPs may be used as markers to examine the genetic predisposition of individuals to wrinkles and sagging.

Gremlin 2 suppresses differentiation of stem/progenitor cells in the human skin

INTRODUCTION

The skin is comprised of various kinds of cells and has three layers, the epidermis, dermis and subcutaneous adipose tissue. Stem cells in each tissue duplicate themselves and differentiate to supply new cells that function in the tissue, and thereby maintain the tissue homeostasis. In contrast, senescent cells accumulate with age and secrete senescence-associated secretory phenotype (SASP) factors that impair surrounding cells and tissues, which lowers the capacity to maintain homeostasis in each tissue. Previously, we found Gremlin 2 (GREM2) as a novel SASP factor in the skin and reported that GREM2 suppressed the differentiation of adipose-derived stromal/stem cells. In the present study, we investigated the effects of GREM2 on stem cells in the epidermis and dermis.

METHODS

To examine whether GREM2 expression and the differentiation levels in the epidermis and dermis are correlated, the expressions of GREM2, stem cell markers, an epidermal differentiation marker Keratin 10 (KRT10) and a dermal differentiation marker type 3 procollagen were examined in the skin samples (n = 14) randomly chosen from the elderly where GREM2 expression level is high and the individual differences of its expression are prominent. Next, to test whether GREM2 affects the differentiation of skin stem cells, cells from two established lines (an epidermal and a dermal stem/progenitor cell model) were cultured and induced to differentiate, and recombinant GREM2 protein was added.

RESULTS

In the human skin, the expression levels of GREM2 varied among individuals both in the epidermis and dermis. The expression level of GREM2 was not correlated with the number of stem cells, but negatively correlated with those of both an epidermal and a dermal differentiation markers. The expression levels of epidermal differentiation markers were significantly suppressed by the addition of GREM2 in the three-dimensional (3D) epidermis generated with an epidermal stem/progenitor cell model. In addition, by differentiation induction, the expressions of dermal differentiation markers were induced in cells from a dermal stem/progenitor cell model, and the addition of GREM2 significantly suppressed the expressions of the dermal differentiation markers.

CONCLUSIONS

GREM2 expression level did not affect the numbers of stem cells in the epidermis and dermis but affects the differentiation and maturation levels of the tissues, and GREM2 suppressed the differentiation of stem/progenitor cells in vitro. These findings suggest that GREM2 may contribute to the age-related reduction in the capacity to maintain skin homeostasis by suppressing the differentiation of epidermal and dermal stem/progenitor cells.

Predictive value of QRS duration normalized to left ventricular volume for responding to cardiac resynchronization therapy in patients with mid-QRS duration enrolled in the multicenter registry

Background

For cardiac resynchronization therapy (CRT), patients with chronic heart failure (HF) and wide (>150msec) QRS duration (QRSd) received class I/A indication. However, its beneficial effect seemed to be limited for those with mid- (120–150msec) QRSd. Recent studies demonstrated that QRSd normalized to left ventricular end-diastolic volume (QRSd/ LVEDV) improved prediction of clinical outcome in patients with CRT. Therefore, we sought to investigate predictive value of QRSd/LVEDV for responding to CRT in patients with mid-QRSd.

Methods

This was retrospective multi-center observational cohort study. A total 506 consecutive patients who underwent CRT implantation in Tohoku University Hospital and National Cerebral and Cardiovascular Center were evaluated. Exclusion criteria were QRSd less than 120ms, upgrade procedures from other implanted non-CRT devices and bradycardia requiring pacing. We evaluated clinical variables, data of electrocardiogram and transthoracic echocardiography at baseline and 6 months after CRT implantation. Primary endpoint was a HF hospitalization after CRT implantation. Distribution of free from HF hospitalization during follow-up was calculated using Kaplan-Meier curves, and the effects of covariate on the time to endpoint were investigated using a Cox proportional hazards model.

Results

After 199 patients were excluded based on exclusion criterion, remaining 307 patients were included for the analysis. Mean age was 62±14 [SD] years, and 238 (77%) were male. Mean LVEF and LVEDV were 25±9% and 234±82ml, respectively, and 24% of patients had ischemic etiology of HF. During the median 948 days of follow-up, CRT patients with mid QRSd (n=126; 136±10msec), as compared with those with wide QRSd (n=181; 174±17msec), tended to have higher incidence of HF hospitalization (Wilcoxon p=0.03). Multivariate analysis showed that QRSd and QRSd/LVEDV were significant predictors for HF hospitalization in CRT patients with mid QRSd, and cut-off values (137msec of QRSd and 0.65 of QRSd/LVEDV), which was calculated by receiver operative curve analysis, was used for risk stratification. QRSd<137msec was significant negative predictors for HF hospitalization (p=0.005), and Mid-QRSd patients with QRSd≥137msec demonstrated equivalent clinical outcome with those with wide QRSd. Moreover, patients with QRSd/LVEDV≥0.65 tended to have lower incidence of HF hospitalization as compared with those without it among patients with QRSd<137msec (n=64, Figure).

Conclusion

The present study demonstrates that QRSd normalized to left ventricular end-diastolic volume (QRSd/ LVEDV) could be clinical value in predicting outcome in CRT patients with mid-QRSd. These findings indicate normalized QRSd reflects myocardial conduction properties and contribute to risk stratification.

Funding Acknowledgement

Type of funding sources: None.

Establishment of Three Types of Immortalized Human Skin Stem Cell Lines Derived from the Single Donor

Currently, human-skin derived cell culture is a basic technique essential for dermatological research, cellular engineering research, drug development, and cosmetic development. But the number of donors is limited, and primary cell function reduces through cell passage. In particular, since adult stem cells are present in a small amount in living tissues, it has been difficult to obtain a large amount of stem cells and to stably culture them. In this study, skin derived cells were isolated from the epidermis, dermis, and adipose tissue collected from single donor, and immortalization was induced through gene transfer. Subsequently, cell lines that could be used as stem cell models were selected using the differentiation potential and the expression of stem cell markers as indices, and it was confirmed that these could be stably cultured. The immortalized cell lines established in this study have the potential to be applied not only to basic dermatological research but also to a wide range of fields such as drug screening and cell engineering.

Search for genetic loci involved in the constitution and skin type of a Japanese women using a genome-wide association study

The constitution and skin type of individuals are influenced by various factors. Recently, the influence of genetic predispositions on these has been emphasized. To date, genome-wide association studies (GWAS) have shown several single nucleotide polymorphisms (SNPs) that affect individual's constitution and skin type. However, these studies have mainly focused on the Caucasian population, and only a few association analyses with the constitution and skin type of individuals involving a Japanese population have been conducted. In this study, we conducted a GWAS analysis of 9 phenotypes regarding the constitution or skin type of 1108 Japanese women based on a questionnaire. As a result, in addition to SNPs known to be involved in phenotypes in the past, we discovered new SNPs and genetic regions related to darkness of pigmented spots, skin flushing, frequency of rough skin and responsiveness to cosmetics.

Senescent cell removal via JAG1-NOTCH1 signalling in the epidermis

Emerging evidence has pointed to the noxious effects of senescent cells in various tissues, and senescent cells in the epidermis are known to accumulate with age. We hypothesized that there is a mechanism by which senescent cells in the epidermis are preferentially removed and that the function of such removal mechanism declines as age increases. In this study, we investigated whether Notch signalling is involved in such senescent cell removal. We found that Notch1 receptor was expressed more highly in p16INK4a-positive senescent cells than in surrounding cells in human epidermis both in young and old subjects. On the other hand, the expression of its ligand JAG1 was decreased in the epidermis of aged subjects. When normal epidermal cells and UVB-irradiated senescent cells were mixed and three-dimensional reconstructed epidermis was developed in vitro, the senescent cells were preferentially removed from the basal layer and located in the upper layer. We also found that the depletion of senescent cells from the basal layer was suppressed by JAG1 knockdown in normal cells or using a Notch signalling inhibitor. From these results, Notch signalling may be involved in senescent cell removal in the epidermis and the age-related decrease of JAG1 expression in the basal layer may lead to accumulation of senescent cells owing to reduced activation of Notch signalling.

Increase of gremlin 2 with age in human adipose-derived stromal/stem cells and its inhibitory effect on adipogenesis

Introduction

Adipose-derived stromal/stem cells (ASCs) have attracted attention as a promising material for regenerative medicine. Previously, we reported an age-related decrease in the adipogenic potential of ASCs from human subjects and found that the individual difference in this potential increased with age, although the mechanisms remain unclear. Recently, other groups demonstrated that a secreted antagonist of bone morphogenetic protein (BMP) signaling, Gremlin 2 (GREM2), inhibits the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) into osteoblasts and the adipogenesis of 3T3-L1 cell. Here, we examined the effects of GREM2 on the differentiation of ASCs into adipocytes.

Methods

To examine changes in GREM2 expression levels with age, immunohistochemistry was performed on subcutaneous adipose tissues from subjects 12–97 years of age. Next, GREM2 gene expression levels in ASCs collected from subjects 5–90 years of age were examined by RT-PCR, and the change with age and correlation between the expression level and the adipogenic potential of ASCs were analyzed. In addition, to assess whether GREM2 affects adipogenesis, ASCs (purchased from a vendor) were cultured to induce adipogenesis with recombinant GREM2 protein, and siRNA-induced GREM2 knockdown experiment was also performed using aged ASCs.

Results

In adipose tissues, GREM2 expression was observed in cells, including ASCs, but not in mature adipocytes, and the expression level per cell increased with age. GREM2 expression levels in ASCs cultured in vitro also increased with age, and the individual differences in the level increased with age. Of note, partial correlation analysis controlled for age revealed that the adipogenic potential of ASCs and the GREM2 gene expression level were negatively correlated. Furthermore, based on a GREM2 addition experiment, GREM2 has inhibitory effects on the adipogenesis of ASCs through activation of Wnt/β-catenin signaling. On the other hand, GREM2 knockdown in aged ASCs promoted adipogenesis.

Conclusions

The GREM2 expression level was confirmed to play a role in the age-related decrease in adipogenic potential observed in ASCs isolated from adipose tissues as well as in the enhancement of the individual difference, which increased with age. GREM2 in adipose tissues increased with age, which suggested that GREM2 functions as an inhibitory factor of adipogenesis in ASCs.

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GREM2 in human adipose tissues increase with age.

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GREM2 expression in adipose-derived stromal/stem cells (ASCs) increased with age.

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In ASCs, adipogenic potential and GREM2 expression showed a negative correlation.

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Recombinant GREM2 inhibited the adipogenesis of ASCs.

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GREM2 knockdown in aged ASCs restored adipogenesis.

Extracellular proteoglycan decorin maintains human hair follicle stem cells

Hair follicle stem cells (HFSC) are localized in the bulge region of the hair follicle and play a role in producing hair. Recently, it has been shown that the number of HFSC decreases with age, which is thought to be a cause of senile alopecia. Therefore, maintaining HFSC may be key for the prevention of age-related hair loss, but the regulatory mechanisms of HFSC and the effects of aging on them are largely unknown. In general, stem cells are known to require regulatory factors in the pericellular microenvironment, termed the stem cell niche, to maintain their cell function. In this study, we focused on the extracellular matrix proteoglycan decorin (DCN) as a candidate factor for maintaining the human HFSC niche. Gene expression analysis showed that DCN was highly expressed in the bulge region. We observed decreases in DCN expression as well as the number of KRT15-positive HFSC with age. In vitro experiments with human plucked hair-derived HFSC revealed that HFSC lost their undifferentiated state with increasing passages, and prior to this change a decrease in DCN expression was observed. Furthermore, knockdown of DCN promoted HFSC differentiation. In contrast, when HFSC were cultured on DCN-coated plates, they showed an even more undifferentiated state. From these results, as a novel mechanism for maintaining HFSC, it was suggested that DCN functions as a stem cell niche component, and that the deficit of HFSC maintenance caused by a reduction in DCN expression could be a cause of age-related hair loss.

Dermal CD271+ Cells are Closely Associated with Regeneration of the Dermis in the Wound Healing Process

Stem cells have recently been shown to play important roles in wound healing. The aim of this study was to investigate the role of dermal CD271+ cells in wound healing. Full-thickness wounds were produced on the backs of 5-year-old and 24-week-old mice, and time-course of wound closure, CD271+ cell counts, and gene expression levels were compared. Delayed wound healing was observed in 24-week-old mice. The peak of CD271+ cell increase was delayed in 24-week-old mice, and gene expression levels of growth factors in wounded tissue were significantly increased in 5-year-old mice. Dermal CD271+ cells purified by fluorescence-activated cell sorting (FACS) expressed higher growth factors than CD271- cells, suggesting that CD271+ cells play important roles by producing growth factors. This study also investigated dermal CD271+ cells in patients with chronic skin ulcers. Dermal CD271+ cells in patients were significantly reduced compared with in healthy controls. Thus, dermal CD271+ cells are closely associated with wound healing.

Skin-resident stem cells and wound healing

CD271 is common stem cell marker for the epidermis and dermis. We assessed a kinetic movement of epidermal and dermal CD271+ cells in the wound healing process to elucidate the possible involvement with chronic skin ulcers. Epidermal CD271+ cells were proliferated and migrated from 3 days after wounding. Purified epidermal CD271+ cells expressed higher TGFβ2 and VEGFα transcripts than CD271- cells. Delayed wound healing was observed in the aged mice compared with young mice. During the wound healing process, the peak of dermal CD271+ cell accumulation was delayed in aged mice compared with young mice. The expression levels of collagen-1, -3, -5, F4-80, EGF, FGF2, TGFβ1, and IL-1α were significantly increased in young mice compared with aged mice. Furthermore, purified dermal CD271+ cells expressed higher FGF2, EGF, PDGFB, and TGFβ1 gene transcripts than CD271- cells. These results suggested that epidermal and dermal CD271+ cells were closely associated with wound healing process by producing various growth factors. Epidermal and dermal CD271+ cells in chronic skin ulcer patients were significantly reduced compared with healthy controls. Thus, both epidermal and dermal stem cells can play an important role in wound healing process.

Senescent dermal fibroblasts enhance stem cell migration through CCL2/CCR2 axis

During aging, increases in the number of senescent cells are seen in various tissues. On the other hand, stem cells play crucial roles in tissue repair and homeostasis. Therefore, it is likely that stem cells give rise to new cells that replace senescent cells. However, how stem cells contribute to homeostasis in the dermis has not been elucidated. Here, we investigated the effects of factors secreted from senescent fibroblasts on stem cells. We found that senescent human dermal fibroblast (HDF) conditioned medium (CM) significantly enhanced stem cell migration compared with young HDF CM. The senescent HDF CM strongly secreted chemokine ligand 2 (CCL2). Furthermore, CCL2 was found to enhance stem cell migration, and the inhibition of CCR2, a receptor for CCL2, reduced stem cell migration. These results suggest that senescent fibroblasts recruit stem cells by secreting various factors and that the CCL2/CCR2 axis is one of the mechanisms underlying this phenomenon.

Bleomycin inhibits adipogenesis and accelerates fibrosis in the subcutaneous adipose layer through TGF-β1

Systemic sclerosis [scleroderma (SSc)]-associated skin fibrosis is characterized by increased fibrosis in the dermis and a reduction in the thickness of the subcutaneous adipose tissue layer. Although many studies have examined fibrosis in SSc, only a few studies have focused on the associated reduction in the thickness of the subcutaneous adipose tissue layer. In this study, we investigated the effects of SSc-induced fibrosis on adipose tissue. We found that bleomycin suppresses adipogenesis in adipose-derived stem cells (ASCs) and stimulates ASCs to express transforming growth factor β1 (TGF-β1), which suppresses adipogenesis and promotes fibrosis. Furthermore, we found that adipocyte-conditioned medium suppressed collagen synthesis by fibroblasts in fibrosis-like conditions. We concluded that in the skin affected by bleomycin-induced fibrosis, increased TGF-β1 expression suppresses adipogenesis and promotes adipocyte fibrosis. It was also suggested that adipocytes have an inhibitory effect on the progression of fibrosis.

Age-related changes of p75 neurotrophin receptor-positive adipose-derived stem cells

BACKGROUND

The existence of multipotent stem cells in subcutaneous adipose tissue has been reported. We previously confirmed that p75 neurotrophin receptor (p75NTR; CD271)-positive cells in subcutaneous adipose tissue possessed multipotency, although changes of the characteristics in p75NTR-positive adipose-derived stem cells (ASCs) with aging remain unclear.

OBJECTIVE

To investigate the effect of aging on p75NTR-positive ASCs.

METHODS

The number of p75NTR-positive ASCs in subcutaneous adipose tissue of ICR mice aged 3-24 weeks was analyzed by immunostaining and flow cytometry. Subsequently, the cells were isolated and their ability to attach to the cell culture dish, proliferation rate (doubling time) and the expression of senescence-associated beta-galactosidase (SA-beta gal), a cellular senescence marker, were assessed. Age-related changes in the differentiation potential of p75NTR-positive cells in adipogenic, osteogenic, chondrogenic and myogenic lineage were also investigated.

RESULTS

The number of ASCs per unit of tissue weight in adipose tissue and the attachment rate of isolated cells decreased with aging. No difference in the cell proliferation rate and the percentage of SA-beta gal-positive cells was detected. Although the efficacy of differentiation into adipogenic and osteogenic lineages slightly decreased with aging, the differentiation potential into chondrogenic and myogenic lineages was not changed.

CONCLUSION

The number of ASCs per unit of tissue weight decreased in aged mice. However, the cells possessed proliferation and differentiation potentials almost equal to those of young mice even though the differentiation potentials showed a tendency of decrease. These results raise the possibility that stem cell functions, self-renewal and multipotency, are maintained regardless of aging.

A novel function of thrombin-activatable fibrinolysis inhibitor during rat liver regeneration and in growth-promoted hepatocytes in primary culture

Thrombin-activatable fibrinolysis inhibitor (TAFI) exhibits anti-fibrinolytic activity by removing C-terminal lysine residues from fibrin or plasminogen receptor proteins on the cellular surface, and plays an important role in the regulation of fibrinolysis. In this study, we examined the regulation of TAFI in hepatocytes during liver regeneration, and revealed its pivotal role in hepatocyte proliferation. In rat models, partial hepatectomy or carbon tetrachloride (CCl4)-induced acute liver injury suppressed the levels of plasma TAFI activity and hepatic TAFI mRNA, whereas this operation markedly increased both the hepatic plasmin activity and the level of proliferating cell nuclear antigen. In primary cultures of rat hepatocytes, the TAFI mRNA level was decreased under growth-promoting culture conditions. Treatment of the hepatocytes with TAFI siRNA increased the amount of plasmin on the hepatocytes and promoted hepatocyte proliferation. We concluded that TAFI regulates plasmin activity through its enzymatic activity whereby it reduces the plasminogen-binding capacity of the hepatocytes. The TAFI gene expression is down-regulated in hepatocyte proliferation for producing a fibrinolytic microenvironment suitable for cell growth. This is the first report on the role of TAFI in the pericellular fibrinolysis necessary for cellular proliferation.

Caregiver psychological characteristics predict discontinuation of care for disabled elderly at home

OBJECTIVE

This study sought to determine the predictors of discontinuation of care for the disabled elderly at home using multivariate regression analysis.

METHODS

In January to February 2005, using a self-administered questionnaire, data were collected from 193 caregivers of frail elderly listed on a roster for utilization of day service or short stay service from two Home Visit Nursing Care Stations. Family caregivers were defined as co-resident family members who provided a minimum of 1 h of daily care for at least 3 months. Multiple stepwise logistic regression analysis was performed to detect predictors of a discontinuation for the disabled elderly at home.

RESULTS

The mean age of caregivers was around 59.0 years, accounting for about 80% of the women among caregivers. Of those caregivers, the proportion of desire to institutionalization (high DI) (56.8%) was higher than that of desire to care at home (low DI) (43.2%). Among the following three factors selected by multivariate stepwise logistic regression analysis, the strength of the relationship was stronger in frequent mood swings and irritability as carerecipient characteristic (adjusted OR = 5.93; 95% CI, 2.09-16.8) than in no advanced or skilled care (adjusted OR = 3.13; 95% CI, 1.41-7.14) and a high caregiver burden (adjusted OR = 1.12; 95% CI, 1.03-1.23) as caregiver's one.

CONCLUSIONS

Our results suggest that the carerecipients' psychological characteristics may be more strongly related to the decision to continue care for disabled elderly at home than that of the caregivers'.

Formation of rat hepatocyte spheroids on agarose

The hepatocyte spheroid formation on the Primariatrade mark dish (PM) occurred as a result of cell migration, adhesion, and shape changes. On the other hand, hepatocytes plated on 1.5% agarose-coated dishes did not attach to the dishes. The formation of spheroids on the agarose-coated dishes was significantly more rapid than that on the PM ones. The PA/plasmin system plays an important role in the process of hepatocyte spheroid formation on PM dishes, and thus the spheroid formation on PM is inhibited by plasmin inhibitors. Nevertheless, these inhibitors did not show any effect on the spheroid formation on agarose-coated dishes. PA activities could be detected in the conditioned medium harvested from the cells cultured on PM dishes, but not in that from those cultured on the agarose-coated dishes. In summary, we have established a novel method to form hepatocyte spheroids by using agarose-coated dishes, in which some mechanism(s) independent of the PA/plasmin system is involved in their formation. The differentiated hepatocyte-specific functions of the spheroids formed on the agarose-coated dishes were expressed to a quite lesser degree than those formed on the PM ones, suggesting that the processes involved in spheroid formation are important for the expression of spheroid functions.

Plasminogen activator/plasmin system regulates formation of the hepatocyte spheroids

The isolated rat hepatocytes inoculated onto the surface of positively charged culture dishes are anchored initially and then begin to migrate and aggregate gradually to form multicellular spheroids detached from the dish. We studied the roles of fibrinolytic factors in the spheroid formation. The fibrinolytic factors, tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA), were increased in the course of spheroid formation. Then, we introduced fibrinolytic inhibitors into the spheroid cultures to determine functions of fibrinolytic factors. Plasmin inhibitor inhibited markedly the spheroid formation. Interestingly, the anti-plasmin antibody showed different effect depending on the timing of its administration. In summary, we demonstrated for the first time that induction of PAs and ensuing plasmin generation on the cell surface play important roles in hepatocyte spheroid formation, and that plasmin is involved in the different processes such as cell migration and cell detachment in the formation of hepatocyte spheroid.

Plasminogen activator-plasmin system potentiates the proliferation of hepatocytes in primary culture

BACKGROUND/AIMS

Liver regeneration after partial hepatectomy is thought to be regulated by various molecules including the components of the plasminogen activator (PA)-plasmin system. We have examined the role of fibrinolytic factors, i.e., tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), and their substrate, plasminogen, in the proliferation of hepatocytes in primary culture.

METHODS

Hepatocyte and nonparenchymal liver cells were isolated from Wistar strain rat by a method perfusing the liver with collagenase. DNA synthesis was assessed by measuring the incorporation of [3H]-thymidine into cellular DNA fraction. tPA, uPA and type-1 plasminogen activator inhibitor (PAI-1) gene expressions were measured by Northern blotting. PA activity was measured by fibrin/agarose plate method.

RESULTS

Cellular density-dependent DNA synthesis was observed in the primary cultured hepatocytes; DNA synthesis was lower at high cell density (1.0 x 10(5) cells/cm(2)) than that at low cell density (0.2 x 10(5) cells/cm(2)). DNA synthesis in the hepatocytes cultured at a low cell density was increased by co-culture with nonparenchymal liver cells. Under these growth-stimulated culture conditions, tPA and uPA mRNAs were induced and up-regulated. On the contrary, the PAI-1 mRNA level was decreased under these conditions, and total PA activity was augmented accordingly. The synthetic plasmin inhibitor tranexamic acid, a competitive inhibitor for the plasmin molecule, and PASI-535, a plasmin active center-directed inhibitor, both suppressed hepatocyte proliferation in a dose-dependent fashion. Anti-plasmin antibody also suppressed hepatocyte proliferation.

CONCLUSIONS

The up-regulation of PA activity for ensuring plasmin activity should be an important mechanism in the proliferation of hepatocytes.

Initial fermentation of sea sludge using aerobic and thermophilic microorganisms in a mangrove soil

As sea sludge has the potential to cause eutrophication and red tide resulting in the death of shellfish and offensive odors, an effective method to treat it is needed. It was found that adding soil taken from a mangrove swamp to sea sludge promoted an initial fermentation of the sludge constituents. The result suggested that certain microorganisms that were thought to inhabit the sub-tropical mangrove soil had the potential to play a significant role in the fermentation and that the use of the microorganisms in the mangrove soil might be useful for composting sea sludge.

[Percutaneous cryosurgery for liver tumors]

A new cryoprobe developed in our department makes it possible to perform percutaneous cryoablation for small liver tumors. This cryoprobe is placed into each lesion using an ultrasonic guidance technique. In this study there were 10 patients with hepatocellular carcinoma and 5 patients with liver metastases from colorectal carcinoma. In 6 cases the tumor size was below 2 cm, in 6 cases between 2 and 3 cm, and in 3 cases over 3 cm. Using a cryoprobe of 3 mm in diameter, each lesion was frozen using liquid nitrogen for 15 or 20 minutes then thawed for 10 minutes, and repeated. The ice ball was found to enlarge to 3 cm in 20 minutes and 5 cm in 60 minutes experimentally. Six cases were CR, 5 PR, 2 NC and 2 PD. After cryoablation, liver function did not change and there were no complications. However, as the size of the ice ball was small (about 3 cm), this method was insufficiently effective in some cases. Percutaneous cryoablation using this probe should be performed for tumors smaller than 3 cm.

Pleasant odors attenuate the blood pressure increase during rhythmic handgrip in humans

We have investigated the effects of inhaling odors of preference on physiological responses to physical exercise in college students. Rhythmic handgrip, maintaining a mercurial pressure by repetitive compression, increased blood pressure. In the participants exercised with inhaling odors of their choice, such as rose, jasmine and lavender, the increase in diastolic blood pressure during exercise was reduced by 24%. In contrast, the blood pressure increase during static handgrip, maintaining the power 30-40% of maximum, was not affected by the existence of favorite odors. Since the blood pressure increase during static handgrip is a lower brainstem reflex, the present result shows that the inhalation of favorite odors suppresses the muscle sympathetic vasoconstrictor activity and attenuates the blood pressure increase by affecting the central nervous system higher than the midbrain.

Pentoxifylline inhibition of vasculogenesis in the neonatal rat retina

PURPOSE

The zeta isozyme of protein kinase C (PKC) is essential for activation of the transcription factor nuclear factor (NF)kappaB and transcription of vascular endothelial growth factor (VEGF). This study examined the antiangiogenic potential of an existing drug, pentoxifylline (PTX), which inhibits PKC-dependent activation of NFkappaB and is reported to prevent hypoxia-induced expression of VEGF.

METHODS

Neovascularization was induced by maintaining neonatal rats for 10 full days in 80% oxygen, interrupted daily by 30 minutes in room air followed by a progressive return to 80% oxygen. On experimental day 11, they were placed in room air until they were killed on day 17. Daily intraperitoneal injections of PTX in saline (25 or 75 mg/kg per day), or saline alone, were administered from day 6 through day 16. Retinal neovascularization was scored, and avascular areas (AVAs) were measured in ADPase stained retinas.

RESULTS

PTX inhibited radial extension of retinal vessels, causing increases in AVA of 65% (P < 0.01) and 33% (P < 0.15) at the lower and upper doses, respectively. A significant increase in mean neovascular score was seen at the lower dose (P < 0.0001), but analysis of variance indicated that neovascularization was strongly and positively influenced by the AVA (P < 0.0001) and only weakly stimulated by PTX (P < 0.05).

CONCLUSIONS

Systemic PTX significantly inhibited VEGF-mediated retinal vasculogenesis, but was not effective in reducing neovascularization in the oxygen-exposed neonatal rat.

A comparison of distilled water and normal saline as diluents for endobronchial administration of epinephrine in the dog

We compared the effects of distilled water and normal saline as diluents for the endobronchial administration of epinephrine in anesthetized dogs by using a cross-over design. Six dogs received 2 mL of either normal saline or distilled water into the bronchus, and the other solution was administered 1 wk later. Eight dogs received 0.02 mg/kg epinephrine diluted in either distilled water (E + water) or normal saline (E + saline) to a total volume of 2 mL into the bronchus, and the other solution was administered 1 wk later. Normal saline or distilled water without epinephrine did not affect the plasma epinephrine concentration, mean arterial pressure (MAP), and PaO(2). The peak plasma epinephrine concentration was significantly larger after treatment with E + water (26.5 +/- 7.9 ng/mL) than after E + saline (2.1 +/- 0.7 ng/mL). E + water caused an increase in MAP of 91 +/- 24 mm Hg, whereas E + saline did not affect MAP. The maximal decrease in PaO(2) after the administration of E + water (14 +/- 5 mm Hg) was significantly greater than after E + saline (7 +/- 2 mm Hg). In conclusion, distilled water as the diluent for endobronchially administered epinephrine to a total volume of 2 mL allowed better absorption of epinephrine compared with normal saline without a serious detrimental effect on PaO(2).

IMPLICATIONS

Using a small volume of distilled water as the diluent for endobronchial epinephrine administration significantly increased epinephrine absorption and arterial pressure in comparison with normal saline, without having a serious detrimental effect on PaO(2), in an anesthetized, noncardiopulmonary, resuscitation dog model.