Skin Of Sprague-Dawley Rats Research Articles

Liposomes and transferosomes in the delivery of papain for the treatment of keloids and hypertrophic scars

Hypertrophic scars and keloids are characterized by an excessive collagen deposition. The available treatment options are invasive and can result in recurrence of scar formation. Using liposomes and transferosomes for the topical delivery of papain, a proteolytic enzyme, can be effective treatment. The objective of the study is to formulate papain-loaded liposomes and transferosomes, characterize the formulations, and study in vitro permeation using shed snake skin and Sprague-Dawley rat skin as models for stratum corneum and full thickness skin. Papain-loaded liposomes and transferosomes were formulated using the thin-film hydration method for the delivery of papain across the stratum corneum barrier. An in vitro permeation study carried out using shed-snake skin and Sprague-Dawley rat skin models showed that transferosomes were able to deliver papain across the stratum corneum barrier, while papain solution and papain liposomes were not able to cross the barrier. However, transferosomes were not able to deliver papain across the full thickness rat skin model suggesting the deposition of papain loaded transferosomes in the epidermal or dermal layer of skin. In addition, an ex-vivo model was used to analyze the effect of papain exposure on the morphology of the epidermis taken from rat skin exposed to papain solution, papain in transferosomes and papain in liposomes. Papain in solution resulted in a noticeable degradation of the epidermis, but when embedded in either transferosomes or liposomes there was no noticeable change when compared to control animals. The cytotoxicity study performed using HeLa cells showed that the cells were viable at papain concentrations lower than 0.01 mg/ml.

Long-term antibacterial activity of silver-containing hydroxyapatite coatings against Staphylococcus aureus in vitro and invivo

BackgroundThe potential of silver-containing hydroxyapatite (Ag-HA) coatings to prevent orthopaedic implant-associated infection was explored previously; however, the resistance of Ag-HA coatings to late-onset orthopaedic infections is unknown. This study aimed to evaluate the long-term Ag+ elution and antibacterial properties of the Ag-HA coatings through in vitro and in vivo experiments. MethodsAg-HA-coated disc specimens were immersed in fetal bovine serum (FBS) for six months. Ag concentration was measured over time using inductively coupled plasma-mass spectrometry to evaluate Ag release. The hydroxyapatite (HA)- or Ag-HA-coated disc specimens were immersed in FBS for 3 months to elute Ag+ for in vitro experiments. Methicillin-resistant Staphylococcus aureus (MRSA) suspensions were inoculated onto each disc; after 48 h, the number of colonies and the biofilm volume were measured. HA- or Ag-HA-coated disc specimens were inserted under the skin of Sprague-Dawley rats for three months for in vivo experiments. In in vivo experiment 1, specimens were inoculated with MRSA and the number of colonies was counted after 48 h. In in vivo experiment 2, the specimens were inoculated with bioluminescent S. aureus Xen36 cells, and bioluminescence was measured using an in vivo imaging system. ResultsThe Ag-HA-coated disc specimens continued to elute Ag+ after six months. The biofilm volume in the Ag-HA group was lower than in the HA group. In in vitro and in vivo experiment 1, the bacterial counts in the Ag-HA group were lower than those in the HA group. In in vivo experiment 2, the bioluminescence in the Ag-HA group was lower than that in the HA group on days 1–7 after inoculation. ConclusionsThe Ag-HA-coated discs continued to elute Ag+ for a long period and exhibited antibacterial activity and inhibition of biofilm formation against S. aureus. The Ag-HA coatings have the potential to reduce late-onset orthopaedic implant-associated infections.

The multiscale characterization and constitutive modeling of healthy and type 2 diabetes mellitus Sprague Dawley rat skin.

In type 2 diabetes mellitus (T2DM), elevated glucose level impairs the biochemistry of the skin which may result in alteration of its mechanical and structural properties. The several aspects of structural and mechanical changes in skin due to T2DM remain poorly understood. To fill these research gaps, we developed a non-obese T2DM rat (Sprague Dawley (SD)) model for investigating the effect of T2DM on the in vivo strain stress state, mechanical and structural properties of skin. In vivo strain and mechanical anisotropy of healthy and T2DM skin were measured using the digital imaging correlation (DIC) technique and DIC coupled bulge experiment, respectively. Fluorescence microscopy and histology were used to assess the collagen and elastin fibers microstructure whereas nanoscale structure was captured through atomic force microscopy (AFM). Based on the microstructural observations, skin was modeled as a multilayer membrane where in and out of plane distribution of collagen fibers and planar distribution of elastin fibers were cast in constitutive model. Further, the state of in vivo stresses of healthy and T2DM were measured using model parameters and in vivo strain in the constitutive model. The results showed that T2DM causes significant loss in in vivo stresses (p < 0.01) and increase in anisotropy (p < 0.001) of skin. These changes were found in good correlation with T2DM associated alteration in skin microstructure. Statistical analysis emphasized that increase in blood glucose concentration (HbA1c) was the main cause of impaired biomechanical properties of skin. The presented data in this study can help to understand the skin pathology and to simulate the skin related clinical procedures. STATEMENT OF SIGNIFICANCE: Our study is significant as it presents findings related to the effect of T2DM on the physiologic stress strain, structural and mechanical response of SD rat skin. In this study, we developed a non-obese T2DM SD rat model which mimics the phenotype of Asian type 2 diabetics (non-obese). Several structural and mechanical characterization techniques were explored for multiscale characterization of healthy and T2DM skin. Further, based on microstructural information, we presented the constitutive models that incorporate the real microstructure of skin. The presented results can be helpful to simulate the realistic mechanical response of skin during various clinical trials.

In vitro and in vivo evaluation of a novel lidocaine-loaded cubosomal gel for prolonged local anesthesia.

Marketed lidocaine dosage forms (such as ointment, gels, and injections) used to manage acute and chronic pain showed a short duration of action (<2 h). In this study, a lidocaine-loaded cubosomal gel was prepared to sustain the release of lidocaine to prolong the local anesthetic effect (high drug retention in the skin). Lidocaine-loaded cubosomal gels were prepared by melt emulsification and sonication using Pluronic F127 and DL-α-monoolein (at different levels). The cubosomal gels were characterized by morphology, size, zeta potential, entrapment efficacy, assay, viscosity, pH, and texture profiles. Ex vivo lidocaine permeation and retention studies were performed using Sprague-Dawley rat skin. Transmission electron microscopy images confirmed the bi-continuous liquid crystalline phase with a honeycomb cubosome structure. The cubosomal particle size (103-227nm), viscosity (13,524-15,627cp), and entrapment efficacy (78.4-94.7%) increase with the level of monoolein. The ex-vivo permeation study showed a biphasic release pattern, with lidocaine cleared from ointment within 4h (97.9% cumulative release), while cubosomal gels showed sustained release up to 24h (53.33-98.86% cumulative release). A skin retention study demonstrated that cubosomes can increase (up to 28-fold) the lidocaine content in the skin (4.56mg) compared to ointment (0.19mg). A rabbit skin irritation study showed no sign of irritation after the application of cubosomal gel. In the radiant heat tail-flick study, the local anesthetic effect of lidocaine from the cubosomal gel was sustained for up to 16h with 1.43-fold higher efficacy than marketed ointment. In conclusion, the study demonstrated the potential of cubosomal nanoparticle-laden gel to sustain the release of lidocaine for prolonging local anesthetic effects for pain management.

The Photocatalytic Effects of Modified Hydrothermal Nanotitania Extraction on the Skin and Behavior of Sprague-Dawley Rats.

Background Potential antibacterial substances, such as titanium dioxide (TiO2), are being extensively studied throughout the research world. A modified hydrothermal nanotitania extraction was shown to inhibit Staphylococcus aureus growth in the laboratory. However, the toxicity effect of the extract on rats is unknown. In this study, we observed the effects of a modified hydrothermal nanotitania extraction on the skin and behavior of Sprague-Dawley rats. Methods Sprague-Dawley (Rattus norvegicus) rats were used as the experimental animals. The skin around the dorsum of the tested animals was shaved and pasted with 0.1 mg and 0.5 mg of the nanotitania extraction. The color and condition of the pasted area and the behavior of the animals were observed. Results 0.1 mg nanotitania extraction application on the dorsum of the rat produced no skin color changes at day 1, day 3, day 5, or day 7 postapplication. There were no changes in their behavior up to day 7 with no skin rashes or skin scratches seen or fur changes. However, 0.5 mg of nanotitania extraction resulted in redness and less fur regrowth at day 7. Conclusions A 0.1 mg modified nanotitania extraction was observed to have no effect on the skin of Sprague-Dawley rats.

Safety of laser-generated shockwave treatment for bacterial biofilms in a cutaneous rodent model.

Bacterial biofilms are often found in chronically infected wounds. Biofilms protect bacteria from antibiotics and impair wound healing. Surgical debridement is often needed to remove the biofilm from an infected wound. Laser-generated shockwave (LGS) treatment is a novel tissue-sparing treatment for biofilm disruption. Previous studies have demonstrated that LGS is effective in disrupting biofilms in vitro. In this study, we aim to determine the safety threshold of the LGS technology in an in vivo rodent model. To understand the in vivo effects of LGS on healthy cutaneous tissue, the de-haired dorsal skin of Sprague-Dawley rats were treated with LGS at three different peak pressures (118, 296, 227 MPa). These pressures were generated using a 1064 nm Nd/YAG laser (pulse duration 5 ns and laser fluence of 777.9 mJ) with laser spot size diameters of 2.2, 3.0, and 4.2 mm, respectively. Following treatment, the animals were observed for 72 h, and a small subset was euthanized at 1-h, 24-h, and 72-h post-treatment and assessed for tissue injury or inflammation under histology. Each treatment group consisted of 9 rats (n = 3/time point for 1-h, 24-h, 72-h post-treatment). An additional 4 control (untreated) rats were included in the analysis, for a total of 31 animals. Gross injuries occurred in 21 (77%) animals and consisted of minor erythema, with prevalence positively correlated with peak pressure (p < 0.05). Of injuries under gross observation, 94% resolved within 24 h. Under histological analysis, the injuries and tissue inflammation were found to be localized to the epidermis and superficial dermis. LGS appears to be well tolerated by cutaneous tissue for the laser energy settings shown to be effective against bacterial biofilm in vitro. All injuries incurred, at even the highest peak pressures, were clinically mild and resolved within 1 day. This lends further support to the overall safety of LGS and serves to translate LGS towards in vivo efficacy studies.

Spironolactone-Loaded LeciPlexes as Potential Topical Delivery Systems for Female Acne: In Vitro Appraisal and Ex Vivo Skin Permeability Studies.

Spironolactone (SP), an aldosterone antagonist with anti-androgen properties, has shown promising results in the treatment of female acne. However, its systemic side effects limit its clinical benefits. This study aimed to prepare and evaluate LeciPlexes for SP topical delivery. LeciPlexes were prepared by a one-step procedure and characterized using various techniques. Optimum LeciPlex preparation was incorporated into 1% methylcellulose gel and SP permeability was tested ex vivo in Sprague-Dawley rat skin. The maximum drug encapsulation efficiency obtained was 93.6 ± 6.9% and was dependent on the drug/phospholipid and surfactant/phospholipid ratios. A zeta potential of +49.3 ± 3.5 to +57.7 ± 3.3 mV and a size of 108 ± 25.3 to 668.5 ± 120.3 nm were observed for the LeciPlexes. FT-IR and DSC studies confirmed the incorporation of SP into the LeciPlexes through hydrophobic and hydrogen bonding interactions. SP release from the LeciPlex formulations was significantly slower than from the drug suspension. Cumulative SP permeated through rat skin from LeciPlex gel was about 2-fold higher than SP control gel. Cumulative SP deposited in the stratum corneum and other skin layers from the LeciPlex gel was about 1.8- and 2.6-fold higher than SP control gel, respectively. This new SP LeciPlex formulation is a promising carrier for the treatment of female acne.

Evaluation of the in vivo wound healing potential of the lipid fraction from activated platelet-rich plasma

Previous in vitro studies suggest a direct relevance for the peptide–free lipid fraction (LF) of platelet-rich plasma (PRP) in biological mechanisms related to wound healing. However, there are no scientific reports to date on the wound healing activities of this lipid component in vivo. Thus, the present study provides a scientific evaluation for the wound healing potential of the lipid portion of the activated PRP. For the wound healing activity assessment, in vivo full‐thickness excisional wounds were created on the dorsal skin of Sprague-Dawley rats. Lipid extract from pooled PRP was applied topically to the wounds on 0, 3, and 7 days after injury. Histological assessment of epidermal and dermal regeneration, granulation tissue thickness and angiogenesis by Sirius red and Masson’s trichrome staining, in addition to immunohistochemical staining for transforming growth factor beta-1 (TGF-β1), collagen type I (COL I), and collagen type III (COL III) were performed on skin biopsies at 3, 7 and 14 days. The total histological scores of the LF group were significantly higher than the 25% dimethylsulfoxide-control group. According to the immunohistochemical staining, the observed expression changes for TGF-β1, COL I and III at 3, 7, and 14 days after wounding were significantly better in the study group than the control group. Furthermore, COL I/III ratio in the lipid extract-treated group at day 14 was much higher than that of the control group. Meanwhile, analysis of the data also indicated that the LF has less positive effects on all evaluated parameters than PRP. From the present data, it could be concluded that the peptide–free LF of PRP has potent wound healing capacity in vivo for cutaneous wounds, although not as much as that of PRP. Strengthening our understanding of the wound healing potential of lipid components of PRP and platelet-derived lipid factors may provide new avenues for improving the healing process of a wound with elevated protease activity.

Response Surface Methodology for Optimization of Ultrasound-Assisted Transdermal Delivery and Skin Retention of Asenapine Maleate

Asenapine maleate (ASP) is an antipsychotic agent used in the treatment of schizophrenia and bipolar disorder. It has extremely low oral bioavailability of < 2%, necessitating the utilization of alternate route of administration. The objective of this work is to study and optimize the sonophoretic transdermal delivery and skin retention of ASP statistically, in Sprague-Dawley rat skin, using response surface methodology in Design of Experiments (DoE). I-optimal design was employed, using the ultrasound (US) parameters viz., duration of US application, amplitude of US, and mode of US application (simultaneous application or pretreatment) as the input variables. Steady-state flux (Jss) of ASP and amount of drug retained in skin after 24 h was taken as the output responses. The model and dependent variables were found to be significant and representative of the data and response surface. While passive diffusion yielded Jss of 2.575 μg/cm2/h, the same values with US application ranged from 8.18 to 127.68 μg/cm2/h. Passive diffusion of drug showed 46.22 ± 5.2 μg/cm2 of ASP retained in 24 h, while US application resulted in 99.07 to 1495.6 μg/cm2 of drug retained in skin in 24 h. Based on the findings from optimization studies, 30 min of US application, with amplitude of 27–28, and simultaneous application mode was found to achieve the optimal transdermal drug flux, with slightly lower retention values in skin. The study found that the sonophoretic transdermal permeation and retention of ASP in vitro could be optimized using response surface methodology.

NOVEL TRANSETHOSOME CONTAINING GREEN TEA (CAMELLIA SINENSIS L. KUNTZE) LEAF EXTRACT FOR ENHANCED SKIN DELIVERY OF EPIGALLOCATECHIN GALLATE: FORMULATION AND IN VITRO PENETRATION TEST

Objective: This study aimed to formulate a transethosome cream (TEC) to increase skin penetration of epigallocatechin gallate (EGCG) in green tealeaf extract and evaluate their physicochemical characteristics and skin penetration capacity.Methods: Transethosomes were prepared through thin-layer hydration method in three formulations (F1−F3) with different Span 80 and ethanol concentrations.Transethosome morphology was characterized using transmission electron microscopy, particle size, polydispersity (PDI), and zeta potential using a particlesize analyzer and entrapment efficiency (EE). Penetration was tested using an in vitro Franz diffusion cell with female Sprague-Dawley rat skin as themembrane.Results: Transethosome F2 containing green tea extract equivalent to 3% EGCG, 4% Lipoid P30, 0.75% Span 80, and 30% ethanol had the bestcharacteristic including spherical shape, smallest particle size (35.35 nm), 0.319 PDI, zeta potential of −29.97±3.05 mV, and highest EE of45.26%±8.15%. TEC permitted greater flux than non-TEC (first phase: 60.56±4.52 vs. 25.69±0.83 μg•cm−2•h−1 and second phase: 23.13±1.38 vs.7.36±1.59 μg•cm−2•h−1).Conclusion: Transethosome can increase the skin penetration of green tea leaf extract.

Formulation and Penetration Enhancement Activity of Sticks Containing Caffeine

Caffeine is a methyl xanthine alkaloid that has been widely used in cosmetic products as anti-cellulite. Caffeine has a hydrophilic character, thus it has difficulty in penetrating the lipid layer of the skin. The aims of this study were to formulate sticks containing emulsion and microemulsion caffeine (control stick), caffeine emulsions (emulsion stick), and caffeine microemulsion (microemulsion stick) and compare the penetration between them. Caffeine was made in the form of water in oil emulsions and microemulsion then form into sticks-shaped with the lipophilic component. All sticks were physically and chemically evaluated. The penetration of caffeine through Sprague-Dawley rat skin using Franz Diffusion Cell were tested for 12 hours. The penetration result of caffeine from control stick, emulsion stick, and microemulsion stick were 306.42 ± 34.92 µg/cm2, 927.75 ± 57.38 µg/cm2, and 2408.68 ± 81.65 µg/cm2 respectively, with percentage 5.90 ± 0.67%, 12.76 ± 0.78%, and 35.23 ± 1.19%. Physical and chemical stability tests were performed for 8 weeks at room temperature (29±2°C), cold temperature (4±2°C), and hot temperature (40±2°C). Microemulsion stick delivered the highest cumulative amount of caffeine in penetration test for 12 hours, followed by emulsion stick and control stick. Also, all sticks showed physical and chemical relatively stable.

Novel Transdermal Ethosomal Gel Containing Green Tea (Camellia sinensis L. Kuntze) Leaves Extract: Formulation and In vitro Penetration Study

Background: One of the natural products that have many benefits is green tea ( Camellia sinensis L.). It can be used to maintain health because of its high antioxidant activity from epigallocatechin gallate (EGCG). However, EGCG has a low ability to penetrate through the skin due to its hydrophilicity. The aim of this study is to improve the penetration of EGCG through the skin by lipid nanovesicle, namely ethosome. Methods: Ethosomes were made using thin layer hydration method. Ethosomes were formulated with different concentration, equal to 1% (F1), 1.5% (F2), and 2% (F3) of EGCG from green tea leaves extract. They were characterized, then a chosen formula would be formulated into a gel dosage form (ethosomal gel). A gel without ethosome (non-ethosomal gel) was prepared as a control. Both of them were evaluated their penetration enhancement ability using Franz diffusion cells with the abdomen skin of Sprague-Dawley rats. Results and Discussion: Based on the results, F1 had a spherical shape, Dv90 129.00 ± 0.00 nm, polydispersity index 0.05 ± 0.00, zeta potential at -62.6 ± 5.05 mV, and the highest entrapment efficiency of 54.39 ± 0.03 %. The cumulative amount of EGCG penetrated from ethosomal and non-ethosmal gel were 1364.28 ± 56.32 μg/cm 2 and 490.17 ± 2.60 μ g/cm 2 , respectively ( p μ g/cm 2 . hour and 31.09 ± 0.29 μ g/cm 2 . hour, respectively. Conclusion: It can be concluded that ethosomal gel can increase the penetration of EGCG from green tea leaves extract. Key words: EGCG, Epigallocatechin Gallate, Ethosomes, Franz Diffusion Cell, Green Tea Leaves Extract, in-vitro Penetration Test.

Effects of different cellulose membranes regenerated from Styela clava tunics on wound healing.

The aim of this study was to investigate the therapeutic effects of three different cellulose membranes (CMs) manufactured from Styela clava tunics (SCTs) on the healing of cutaneous wounds. We examined the physical properties and therapeutic effects of three CMs regenerated from SCTs (referred to as SCT- CMs), including normal CM (SCT-CM), freeze-dried SCT-CM (FSCT-CM) and sodium alginate-supplemented SCT-CM (ASCT-CM) on skin regeneration and angiogenesis using Sprague-Dawley (SD) rats. FSCT-CM exhibited an outstanding interlayered structure, a high tensile strength (1.64 MPa), low elongation (28.59%) and a low water vapor transmission rate (WVTR) compared with the other SCT-CMs, although the fluid uptake rate was maintained at a medium level. In the SD rats with surgically wounded skin, the wound area and score of wound edge were lower in the FSCT-CM-treated group than in the gauze (GZ)-treated group on days 3–6 and 12–14. In addition, a significant attenuation in the histopathological changes was observed in the FSCT-CM-treated group. Furthermore, the expression level of collagen-1 and the signaling pathway of transforming growth factor (TGF)-β1 were significantly stimulated by the topical application of FSCT-CM. However, no signs of toxicity were detected in the livers or kidneys of the three SCT-CM-treated groups. Overall, our data indicate that the FSCT-CM may accelerate the process of wound healing in the surgically wounded skin of SD rats through the regulation of angiogenesis and connective tissue formation without inducing any specific toxicity.

Transdermal iontophoretic delivery of tacrine hydrochloride: Correlation between in vitro permeation and in vivo performance in rats

The aim of present investigation is to evaluate the feasibility of transdermal iontophoretic delivery of tacrine hydrochloride in Sprague Dawley (SD) rats using anodal iontophoretic patches and to correlate plasma tacrine concentration profiles to in vitro tacrine permeation flux. In vitro skin permeation studies were carried out across artificial membrane CELGRAD® 2400, freshly excised SD rat abdominal skin, freshly excised hairless rat abdominal skin, and frozen pig skin to examine the role of permeation membranes. Furthermore, plasma profiles with an application of 0.1–0.3mA current strength and tacrine concentration loading of 5–20mg/ml were obtained in SD rats. The tacrine plasma profiles were fitted to one-compartmental model using WinNonlin and in vivo transdermal absorption rates were then correlated to in vitro permeation profiles using various approaches. Tacrine permeation across membranes revealed current dependent interspecies differences at lower current strength application which diminished at higher current strength application, whereas, no significant difference in tacrine permeation was observed across fresh and frozen SD rat skin under 0.2mA current application. In vivo studies confirmed current and concentration dependent tacrine plasma profiles with possible tacrine depot formation under the skin in-line with earlier in vitro results. Correlation of in vivo transdermal absorption rates to in vitro permeation profiles revealed higher in vitro permeation fluxes compare to in vivo transdermal absorption rates at varied combination of current strength and concentrations. Present in vivo studies support the earlier published in vitro findings and tacrine plasma profiles show a potential to reach therapeutic effective concentration of tacrine hydrochloride to provide a platform for pre-programmed tacrine delivery.

Skin healing and collagen changes of rats after fractional erbium:yttrium aluminum garnet laser: observation by reflectance confocal microscopy with confirmed histological evidence.

The fractional erbium:yttrium aluminum garnet (Er:YAG) laser is widely applied. Microstructural changes after laser treatment have been observed with histopathology. Epidermal and dermal microstructures have also been analyzed using reflectance confocal microscopy (RCM). However, no studies have compared these two types of microstructural changes in the same subject at multiple time points after irradiation, and it is unclear if these two types of changes are consistent. We use RCM to observe the effect of different laser energies on skin healing and collagen changes in the skin of Sprague-Dawley rats that had been irradiated by fractional Er:YAG lasering at different energies. RCM was used to observe skin healing and detect collagen changes at different time points. Collagen changes were observed using hematoxylin and eosin (H&E) staining and quantitatively analyzed by western blot. RCM showed that, irrespective of laser energy, microscopic treatment zones (MTZs) were larger at 1day after irradiation. The MTZs then reduced in size from 3 to 7days after irradiation. The higher the energy, the larger the MTZ area. The amount of collagen also increased with time from 1day to 8weeks. However, the increase in the collagen amount on both RCM and H&E staining was not influenced by the laser energy. Western blotting confirmed that the amount of type I and type III collagens increased over time, but there were no significant differences between the different energy groups (p > 0.05). In conclusion, RCM is a reliable technique for observing and evaluating skin healing and collagen expression after laser irradiation.

Upregulation of Collagen Expression via PPARβ/δ Activation in Aged Skin by Magnesium Lithospermate B from Salvia miltiorrhiza.

This study investigated the agonistic activity of magnesium lithospermate B (1), isolated from Salvia miltiorrhiza, on peroxisome proliferator-activated receptor (PPARβ/δ) and the expressions of collagen genes (COL1A1 and COL3A1) and transforming growth factor-β1 (TGF-β1) in models of skin aging. The action of compound 1 as a PPARβ/δ agonist was determined by reporter gene assay, immunostaining, and Western blotting. To determine the antiaging effects of compound 1 on skin, aged Sprague-Dawley rat skin and ultraviolet B (UVB)-irradiated human skin fibroblasts were used. The results show that 1 presented a marked enhancement of both nuclear protein levels and activity of PPARβ/δ in fibroblasts. In addition, 1 prevented downregulation of PPARβ/δ activity in aged rat skin and UVB-induced fibroblasts. Furthermore, 1 increased the expressions of COL1A1, COL3A1, and TGF-β1 in vivo and in a cell culture system. Therefore, the present study shows that compound 1 prevents collagen degradation in aged rat skin and UVB-exposed fibroblasts through PPARβ/δ activation. The therapeutic and cosmetic applications of compound 1 need further investigation.

Bacterial cellulose membrane produced by Acetobacter sp. A10 for burn wound dressing applications.

Bacteria cellulose membranes (BCM) are used for wound dressings, bone grafts, tissue engineering, artificial vessels, and dental implants because of their high tensile strength, crystallinity and water holding ability. In this study, the effects of BCM application for 15 days on healing of burn wounds were investigated based on evaluation of skin regeneration and angiogenesis in burn injury skin of Sprague-Dawley (SD) rats. BCM showed a randomly organized fibrils network, 12.13 MPa tensile strength, 12.53% strain, 17.63% crystallinity, 90.2% gel fraction and 112.14 g × m(2)/h highest water vapor transmission rate (WVTR) although their swelling ratio was enhanced to 350% within 24h. In SD rats with burned skin, the skin severity score was lower in the BCM treated group than the gauze (GZ) group at all time points, while the epidermis and dermis thickness and number of blood vessels was greater in the BCM treated group. Furthermore, a significant decrease in the number of infiltrated mast cells and in vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) expression was observed in the BCM treated group at day 10 and 15. Moreover, a significant high level in collagen expression was observed in the BCM treated group at day 5 compared with GZ treated group, while low level was detected in the same group at day 10 and 15. However, the level of metabolic enzymes representing liver and kidney toxicity in the serum of BCM treated rats was maintained at levels consistent with GZ treated rats. Overall, BCM may accelerate the process of wound healing in burn injury skin of SD rats through regulation of angiogenesis and connective tissue formation as well as not induce any specific toxicity against the liver and kidney.

Cellulose film regenerated from Styela clava tunics have biodegradability, toxicity and biocompatibility in the skin of SD rats

Cellulose is one of the most widespread biomolecules in nature and has been exploited in various applications including scaffolding, tissue engineering, and tissue formation. To evaluate the biocompatibility of cellulose film manufactured from Styela clava tunics (SCT-CF), these films were implanted in Sprague-Dawley (SD) rats for various lengths of time, after which they were subjected to mechanical and biological analyses. The cellulose powders (12-268 m) obtained from SCT was converted into films via casting methods without adding any additives. SCT-CF contained about 98 % α-cellulose and very low concentrations of ββ-cellulose. Additionally, the crystallinity index (CrI) of SCT-CF was lower (10.71 %) than that of wood pulp-cellulose films (WP-CF) (33.78 %). After implantation for 90 days, the weight loss and formation of surface corrugations were greater in SCT-CF than that of WP-CF, while the surface roughness was significantly higher in WP-CF than SCT-CF. However, there were no differences in the number of white blood cells between SCT-CF implanted rats and vehicle implanted rats. The level of metabolic enzymes representing liver and kidney toxicity in the serum of SCT-CF implanted rats was maintained at levels consistent with vehicle implanted rats. Moreover, no significant alteration of the epidermal hyperplasia, inflammatory cell infiltration, redness, and edema were observed in SD rats implanted with SCT-CF. Taken together, these results indicate that SCT-CF showed good degradability and non-toxicity without inducing an immune response in SD rats. Further, the data presented here constitute strong evidence that SCT-CF has the potential for use as a powerful biomaterial for medical applications including stitching fiber, wound dressing, scaffolding, absorbable hemostats and hemodialysis membrane.

Implications of time‐series gene expression profiles of replicative senescence

Although senescence has long been implicated in aging-associated pathologies, it is not clearly understood how senescent cells are linked to these diseases. To address this knowledge gap, we profiled cellular senescence phenotypes and mRNA expression patterns during replicative senescence in human diploid fibroblasts. We identified a sequential order of gain-of-senescence phenotypes: low levels of reactive oxygen species, cell mass/size increases with delayed cell growth, high levels of reactive oxygen species with increases in senescence-associated β-galactosidase activity (SA-β-gal), and high levels of SA-β-gal activity. Gene expression profiling revealed four distinct modules in which genes were prominently expressed at certain stages of senescence, allowing us to divide the process into four stages: early, middle, advanced, and very advanced. Interestingly, the gene expression modules governing each stage supported the development of the associated senescence phenotypes. Senescence-associated secretory phenotype-related genes also displayed a stage-specific expression pattern with three unique features during senescence: differential expression of interleukin isoforms, differential expression of interleukins and their receptors, and differential expression of matrix metalloproteinases and their inhibitory proteins. We validated these phenomena at the protein level using human diploid fibroblasts and aging Sprague-Dawley rat skin tissues. Finally, disease-association analysis of the modular genes also revealed stage-specific patterns. Taken together, our results reflect a detailed process of cellular senescence and provide diverse genome-wide information of cellular backgrounds for senescence.

Plasma surface chemical treatment of electrospun poly(L-lactide) microfibrous scaffolds for enhanced cell adhesion, growth, and infiltration.

Poly(l-lactide) (PLLA) microfibrous scaffolds produced by electrospinning were treated with mild Ar or Ar-NH3/H2 plasmas to enhance cell attachment, growth, and infiltration. Goniometry, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) measurements were used to evaluate the modification of the scaffold surface chemistry by plasma treatment. AFM and XPS measurements showed that both plasma treatments increased the hydrophilicity without affecting the integrity of the fibrous structure and the fiber roughness, whereas Ar-NH3/H2 plasma treatment also resulted in surface functionalization with amine groups. Culture studies of bovine aorta endothelial cells and bovine smooth muscle cells on the plasma-treated PLLA scaffolds revealed that both Ar and Ar-NH3/H2 plasma treatments promoted cell spreading during the initial stage of cell attachment and, more importantly, increased the cell growth rate, especially for Ar plasma treatment. In vitro cell infiltration studies showed that both plasma treatments effectively enhanced cell migration into the microfibrous scaffolds. In vivo experiments involving the subcutaneous implantation of plasma-treated PLLA scaffolds under the skin of Sprague-Dawley rats also showed increased cell infiltration. The results of this study indicate that surface treatment of PLLA microfibrous scaffolds with mild Ar or Ar-NH3/H2 plasmas may have important implications in tissue engineering. Further modifications with bioactive factors should improve the functions of the scaffolds for specific applications.