Porcine Ear Research Articles

Modulation of Epidermal Growth Factor Release by Biopolymer-Coated Liposomes

This work describes the development of polysaccharide-coated liposomes to modulate the delivery of epidermal growth factor (EGF), with the aim to produce different EGF release profiles depending on the milieu of infected wounds. For this purpose, cationic liposomes were coated with one layer of sodium alginate (ALG) followed by one layer of chitosan (CHI) using the layer-by-layer (LbL) technique. The coated liposomes exhibited apparent hydrodynamic diameters of 278 ± 36 and 216 ± 96 nm for Lip-ALG and Lip-ALG-CHI, respectively. Thus, it appears that adding the CHI layer compacted the Lip-ALG one. The incorporation efficiency of EGF was a maximum of 55% for liposomes with a polymeric coating. In vitro release experiments showed that Lip-ALG-CHI exhibits a higher release rate constant under acidic pH conditions, resembling those of infected tissue. Using an ex vivo model of EGF release in porcine ear skin, these liposomes were found to accumulate in the epidermis. Thus, coated liposomes could represent a local EGF delivery mechanism to promote healing.

Effect of Different Pressure-Sensitive Adhesives on Performance Parameters of Matrix-Type Transdermal Delivery Systems.

Matrix-type transdermal delivery systems (TDS) are comprised of the drug dissolved or dispersed in a pressure-sensitive adhesive (PSA) matrix and are designed to provide a controlled delivery through the skin and into systemic circulation. PSAs can directly affect the permeation, release, and performance characteristics of the system. In this study we aimed to design and characterize transdermal delivery systems formulated with lidocaine—as the model drug—loaded in different PSAs, including silicone, polyisobutylene (PIB), and acrylate. TDS containing lidocaine at its saturation points were prepared by the solvent casting method. In vitro permeation studies across dermatomed porcine ear skin were performed using Franz diffusion cells. In vitro release studies were carried out using USP apparatus 5 (paddle over disk). The cumulative amount permeated from the acrylate was significantly higher than silicone and PIB. The acrylate TDS contained a ten times higher drug amount than silicone TDS, but the permeation flux was only two folds higher. Results also showed the release of drug does not linearly correlate to saturation, as the silicone TDS comprising of the lowest amount of drug loading, showed the highest percentage release indicating the choice of PSA affected the drug release and permeation profile.

Formulación y permeación cutánea ex vivo de geles tópicos de lidocaína HCl usando goma de fruta dillenia (Dillenia indica L.)

Current work was endeavoured to formulate the topical gels of 4 % lidocaine HCl by employing dillenia (Dillenia indica L.,) fruit gum (DG) extracted from ripen fruits (14.73% yield). Physicochemical properties such as colour, odour, taste, aqueous solubility, pH and viscosity of this extracted DG were evaluated. Occurrence of carbohydrates and mucilage was confirmed by phytochemical identification tests and was characterized by employing FTIR and 1H NMR spectroscopy. Employing extracted DG along with Carbopol 940 (as gel-forming materials), propylene glycol (as plasticizer), methyl paraben (as preservative) and menthol (as permeation enhancer), topical gels containing 4 % lidocaine HCl were formulated. The pH and viscosity of these gels were satisfactory. The ex vivo skin permeation of lidocaine HCl across excised porcine ear skin membrane from formulated and marketed topical gels containing 4 % lidocaine HCl exhibited sustained permeation over 7 h. Highest lidocaine HCl permeation flux (1589.66 ± 13.36 µg/cm2/h) was measured for the gel containing 0.1 % menthol. Korsmeyer-Peppas model was found as the best-fitting drug permeation model (R2 = 0.9944-0.9992) with super case-II transport mechanism (n = 0.97-1.07). These topical gels of lidocaine HCl (4 %) were found physically stable enough without syneresis in the freeze thaw cycling process.

Solvent-Containing Closure Material Can Be Used to Prevent Follicular Penetration of Caffeine and Fluorescein Sodium Salt on Porcine Ear Skin

Aim: The skin represents a drug delivery portal. The establishment of a skin model capable of distinguishing between the follicular and intercellular penetration pathways remains a challenge. The study described herein was aimed at showing the influence of two nail varnishes as closure material and four application techniques to spread the active pharmaceutical ingredient (API) on a successful follicular closure without inducing penetration-enhancing effects. Materials and Methods: For all experiments, ex vivo porcine ear skin was used. In study design A, a standard and a solvent-free nail varnish were compared. It was tested whether the different application techniques (spreading with pipette, careful finger massage, 5-Hz finger massage, 5-Hz automatic massage) potentially destroy an intact follicular closure. Laser scanning microscopy imaging was used to measure if the model drug (fluorescein sodium salt) penetrated into the hair follicles. Study design B investigated how the penetration is affected when applying standard nail varnish containing solvents to skin. It was tested if the varnish blocks the API (caffeine) on completely covered areas and if adjacent areas show increased penetration. Furthermore, lateral diffusion of the API was investigated. After 20 h, the skin layers were separated by tape stripping and heat separation. The tissue samples were homogenized. Caffeine was quantified by chromatography. Results: In study design A, the standard nail varnish showed a secure follicular closure, while the solvent-free nail varnish was not able to prevent follicular penetration. Moreover, rapid application techniques were found to destroy an intact follicular closure. Only the two most gentle application techniques kept the follicular closing intact. In study design B, no caffeine was detected in both skin areas that were completely covered. Since no significant difference in caffeine penetration between the two uncovered groups was found, any influence of the applied closure material on adjacent areas was excluded. Conclusion: This study clearly demonstrates that a standard nail varnish in combination with a gentle application technique of the API provides a secure follicular closure. The presented study only investigated the closure for the substances caffeine and fluorescein sodium salt. The results might not be transferable to all kinds of APIs.

Laser scanning microscopy for control of skin decontamination efficacy from airborne particulates using highly absorbent textile nanofiber material in combination with PEG-12 dimethicone.

The decontamination of the skin is indispensable if airborne particulate contaminants deposit on the skin surface. Skin washing can have adverse effects as by skin rubbing the particles can be transferred deeply into the hair follicles, where they can be entrapped for a period of more than 10days. Thus, alternative skin decontamination strategies are necessary. For imaging the contaminants in the skin, sodium fluorescein-labeled soot particles of submicron size (≈600nm) were visualized using laser scanning microscopy. In the present ex vivo pilot study on porcine ear skin, it was shown that sodium fluorescein-labeled soot particles of submicron size (≈600nm) could be efficiently removed from the skin with highly absorbent textile nanofiber material, whose efficacy could be further increased by spraying the contaminated skin area with the viscous fluid PEG-12 dimethicone before textile application. In case of skin contamination with particulates, the contact washing should be avoided due to rubbing particles deeply into the hair follicles, where they can accumulate for a long time and induce negative consequences. Efficient skin decontamination could include pretreatment of skin surface with the viscous fluid PEG-12 dimethicone and subsequent application of highly absorbent textile nanofiber material.

Formulation of drug-loaded oligodepsipeptide particles with submicron size.

The size of particulate carriers is key to their transport and distribution in biological systems, and needs to be tailored in the higher submicron range to enable follicular uptake for dermal treatment. Oligodepsipeptides are promising nanoparticulate carrier systems as they can be designed to exhibit enhanced interaction with drug molecules. Here, a fabrication scheme for drug-loaded submicron particles from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diol (OBMD) is presented based on an emulsion solvent evaporation method with cosolvent, surfactant, and polymer concentration as variable process parameters. The particle size (300-950 nm) increased with lower surfactant concentration and higher oligomer concentration. The addition of acetone increased the particle size at low surfactant concentration. Particle size remained stable upon the encapsulation of models compounds dexamethasone (DXM) and Nile red (NR), having different physicochemical properties. DXM was released faster compared to NR due to its higher water solubility. Overall, the results indicated that both drug-loading and size control of OBMD submicron particles can be achieved. When applied on porcine ear skin samples, the NR-loaded particles have been shown to allow NR penetration into the hair follicle and the depth reached with the 300 nm particles was comparable to the one reached with the cream formulation. A potential benefit of the particles compared to a cream is their sustained release profile.

Topical nano-encapsulated cyclosporine formulation for atopic dermatitis treatment

Systemic cyclosporine A (CsA) therapy shows efficacy in the treatment of recalcitrant severe atopic dermatitis (AD) but elicits severe side-effects. Thus, a topical formulation of CsA nanocapsules (NCs), able to potentially bypass these drawbacks, was developed. CsA-NCs were shown to enhance drug penetration into the various layers of porcine ear skin. Furthermore, the encapsulated CsA was biologically active, as shown in vitro on mouse splenocytes, reflected by inhibition of both cell proliferation and of interleukin (IL)-2 secretion. Ex-vivo efficacy was demonstrated on human skin organ culture by markedly reducing pro-inflammatory cytokines secretion. Finally, CsA-NCs topical formulation elicited improved efficacy in terms of better preservation of the skin barrier integrity, a decrease of the systemic pro-inflammation markers and reduced skin inflammation. The overall results suggest that this original topical platform may provide a novel therapeutic tool of clinical significance compared to the existing topical therapeutic drugs in AD.

Fabrication and characterization of hyaluronic acid microneedles to enhance delivery of magnesium ascorbyl phosphate into skin.

This study investigated the in vitro transdermal delivery of magnesium ascorbyl phosphate (MAP) through porcine ear skin treated with hyaluronic acid (HA) microneedles (MNs). In this study, the micro-molding method was used to fabricate HA MNs. HA solution (10% w/v) containing 3% of MAP was placed onto a poly(dimethyl siloxane) mold to fill the microchannels under vacuum followed by drying in a desiccator. Scanning electron microscopy was performed to record the dimensions of the MNs. Skin microporation was demonstrated by dye binding. Histological skin sections revealed the shape of microchannels under hematoxylin-eosin staining. The actual depth of the microchannels and drug distribution pathways were studied by confocal microscopy. In vitro permeation on Franz diffusion cells were performed to determine the rate and extent of drug delivery into and across the skin. SEM captured individual MNs from the array, and the length of each MN was found to be ~400μm. The 10 × 10 MN array prepared, resulted in the formation of 95 to 100 microchannels after 2mins of treatment. In addition, the histological evaluations showed the formation of microchannels in the skin, complementary in shape to the MNs. The depths of the formed microchannels amounted to ~125μm as determined by confocal microscopy. The application of the current MN technology enhanced the delivery of MAP into skin (96.8 ± 3.9μg/cm2) compared to the passive delivery strategy of MAP (44.9 ± 16.3μg/cm2). HA MNs markedly enhanced the in vitro transdermal delivery of MAP into and across skin.

Luliconazole vesicular based gel formulations for its enhanced topical delivery

Luliconazole is a new drug candidate for treatment of topical fungal infections. Its present therapy is associated with limitations of very poor and slow skin permeation, leading to required long term repeated administration for complete cure of disease. Lipid nanocarriers based elastic lipogel and ethogel formulations were developed in strength of 1% w/w and extensively characterized in vitro, ex-vivo, and in vivo and compared for their results to the marketed formulation. The prepared formulations were found to have ideal pH, nanometric vesicle size, encapsulation efficiency (92.7% and 91.2%), zeta potential (−17.0 and −32.8 mV), and viscosity (6.6 and 7.8 Pa.s) with no signs of instability on storage. In vitro activity against Candida albicans and dermatophytes demonstrated the prepared formulations to be 3 and 2.5 times more potent than marketed formulation, respectively. Ex vivo skin permeation and deposition studies, performed on various biological membranes and a synthetic membrane, manifest that Strat-M membrane resembles closest to the human skin followed by porcine ear skin, rat, and mice skin. Enhanced skin deposition of elastic lipogel and ethogel as compared to conventional marketed cream is also confirmed by SEM and CLSM analysis of the treated skin. In vivo antifungal activity on albino rats demonstrated vesicle based gel formulations to be safe, non irritant and more effective in topical treatment of fungal infections, with no drug reaching to systemic circulation. Thus, findings of the study demonstrate elastic liposomes and ethosomes, as a carrier are an attractive approach for enhanced topical delivery of Luliconazole.

Tacrolimus-loaded lecithin-based nanostructured lipid carrier and nanoemulsion with propylene glycol monocaprylate as a liquid lipid: Formulation characterization and assessment of dermal delivery compared to referent ointment.

Nanostructured lipid carriers (NLC) and nanoemulsions (NE) are colloid carriers which could improve dermal delivery of tacrolimus. The aims of this study were to evaluate effects of different formulation and process parameters on physicochemical characteristics and stability of lecithin-based NLC with glyceryl palmitostearate as solid and propylene glycol monocaprylate as liquid lipid and to compare the influence of different inner structure of tacrolimus-loaded NLC and corresponding NE on physicochemical characteristics, stability, entrapment efficiency, in vitro drug release and overall skin performance. Solid/liquid lipid ratio, total amount of lipids, homogenization pressure and cooling after the preparation were identified as critical variables in NLC development. Moreover, tacrolimus-loaded NLC emerged as more stabile carrier than NE. Differential stripping performed on porcine ear skin revealed significantly higher tacrolimus amount in stratum corneum from nanocarriers compared to referent ointment (Protopic®). Similarly the highest amount of tacrolimus in hair follicles was obtained using NLC (268.54 ± 92.38 ng/cm2), followed by NE (128.17 ± 48.87 ng/cm2) and Protopic® (77.61 ± 43.25 ng/cm2). Contrary, the highest permeation rate through full-thickness porcine ear skin was observed for Protopic®, implying that the selection of experimental setup is critical for reliable skin performance assessment. Overall, developed NLC could be suggested as promising carrier in a form of lotion for tacrolimus dermal delivery.

Design and Evaluation of a Poly(Lactide-co-Glycolide)-Based In Situ Film-Forming System for Topical Delivery of Trolamine Salicylate.

Trolamine salicylate (TS) is a topical anti-inflammatory analgesic used to treat small joint pain. The topical route is preferred over the oral one owing to gastrointestinal side effects. In this study, a poly(lactide-co-glycolide) (PLGA)-based in situ bio-adhesive film-forming system for the transdermal delivery of TS was designed and evaluated. Therefore, varying amounts (0%, 5%, 10%, 20%, and 25% (w/w)) of PLGA (EXPANSORB® DLG 50-2A, 50-5A, 50-8A, and 75-5A), ethyl 2-cyanoacrylate, poly (ethylene glycol) 400, and 1% of TS were dissolved together in acetone to form the bio-adhesive polymeric solution. In vitro drug permeation studies were performed on a vertical Franz diffusion cell and dermatomed porcine ear skin to evaluate the distinct formulations. The bio-adhesive polymeric solutions were prepared successfully and formed a thin film upon application in situ. A significantly higher amount of TS was delivered from a formulation containing 20% PLGA (45 ± 4 µg/cm2) and compared to PLGA-free counterpart (0.6 ± 0.2 µg/cm2). Furthermore, the addition of PLGA to the polymer film facilitated an early onset of TS delivery across dermatomed porcine skin. The optimized formulation also enhanced the delivery of TS into and across the skin.

Computer-based formulation design and optimization using Hansen solubility parameters to enhance the delivery of ibuprofen through the skin.

Trial-and-error approach to formulation development is long and costly. With growing time and cost pressures in the pharmaceutical industry, the need for computer-based formulation design is greater than ever. In this project, emulgels were designed and optimized using Formulating for Efficacy™ (FFE) for the topical delivery of ibuprofen. FFE helped select penetration enhancers, design and optimize emulgels and simulate skin penetration studies. pH, viscosity, spreadability, droplet size and stability of emulgels were evaluated. Franz cell studies were performed to test in vitro drug release on regenerated cellulose membrane, drug permeation in vitro on Strat-M® membrane and ex vivo on porcine ear skin, a marketed ibuprofen gel served as control. Emulgels had skin compatible pH, viscosity and spreadability comparable to a marketed emulgel, were opaque and stable at 25 °C for 6 months. Oleyl alcohol (OA), combined with either dimethyl isosorbide (DMI) or diethylene glycol monoethyl ether (DGME) provided the highest permeation in 24 h in vitro, which was significantly higher than the marketed product (p < 0.01). OA + DGME significantly outperformed OA ex vivo (p < 0.05). The computer predictions, in vitro and ex vivo penetration results correlated well. FFE was a fast, valuable and reliable tool for aiding in topical product design for ibuprofen.

Effects of Temperature and Humidity on the Skin Permeation of Hydrophilic and Hydrophobic Drugs.

The humidity was a well-known method to hydrate the skin; however, the published data were varied, and systemic experiments in the previous papers were few. Therefore, the in vitro permeation of excised porcine ear skin by drugs with different polarities [aminopyrine (AMP), antipyrine (ANP), methylparaben (MP), and ibuprofen (IP)] was analyzed under a constant skin surface temperature with different temperatures and humidities to reveal the effects of temperature and humidity on the skin permeation enhancement effects. Applied formulations were prepared by mixing the drug and a hydrophilic vehicle containing glycerin. The disposition-distance profiles of water and the humectant glycerin in the stratum corneum were also investigated using confocal Raman microscopy. High absolute humidity (AH) significantly contributed to the high skin penetration of the hydrophilic penetrants AMP, ANP, and MP but not the hydrophobic penetrant IP. An increase in the partition parameter and a decrease in the diffusivity parameter occurred with an increase in AH, independent of drug polarity. Moreover, we found that dew condensation induced by high AH on temperature-controlled skin surface may effectively increase water content and may provide higher glycerin distribution in the skin barrier, the stratum corneum. Increasing the amount of water and hydrophilic vehicles such as glycerin in the stratum corneum may enhance the permeation of hydrophilic penetrants AMP, ANP, and MP. These data suggested a dew condensation on the skin surface induced by high AH at a constant skin surface temperature would be important to enhance hydrophilic penetrants.

Hair removal and bioavailability of chemicals: Effect of physicochemical properties of drugs and surfactants on skin permeation ex vivo.

Cosmetic hair removal procedures are everyday routines in our society. However, it is unclear if such routines lead to increased uptake of applied substances such as drugs or formulation compounds, potentially resulting in skin irritation or sensitization. The aim of this study was to elucidate the effect of common depilation and epilation methods on skin penetration of two surfactants and four model drugs of different physicochemical properties using the porcine ear model. It should be elucidated whether the substances' skin penetration behavior would be affected by hair removal procedures and if potential effects would be related to their polarity. Confocal Raman spectroscopy revealed no effect of hair removal on total penetration depths of SDS and sulfathiazole. Significantly higher relative penetrated amounts within 0-6 µm of stratum corneum depth were found for SDS after dry shaving, depilatory cream and waxing and for sulfathiazole after all depilation methods and partly after epilation. ATR-FTIR spectroscopy revealed no effect of hair removal on the penetration depth of lecithin LPC80, but higher relative amounts at the skin surface after wet shaving and electric epilation. Diffusion cell experiments using a lecithin-based microemulsion as carrier system for fluconazole, fludrocortisone acetate and flufenamic acid showed higher cumulative amounts, higher drug fluxes and shorter lag times for the more lipophilic drugs for some of the methods, but only shorter lag times in some cases for fluconazole. In summary, the observed effects appeared to depend on drug polarity and experimental setup.

Maximum Loaded Amorphous Azithromycin Produced Using the Wetness Impregnation Method with Fractional Steps for Dermal Prophylaxis Against Lyme Disease.

Azithromycin was loaded onto the μm-sized mesoporous silica Davisil® SP53D-11920 using the wetness impregnation method with fractional steps (WIFS) and further incorporated into a 5 % hydroxypropyl cellulose gel to prevent Lyme disease. Maximum loadings (32.0 % w/w and 33.2 % w/w) were produced by different concentrated loading solutions and determined by X-ray diffraction (XRD). A total of 24 months stability of the amorphous azithromycin state in the silica (33.2 % loading) and 18 months stability in the gel (33.2 % loading) at 4 °C were also confirmed by XRD. The higher kinetic solubility at 40 min (1,300 μg/mL versus 93 μg/mL) and higher porcine ear skin penetration compared to the raw drug powder indicated higher dermal bioavailability of the azithromycin-loaded silica (32.0 % loading), even when compared to the "gold standard" nanocrystals and another clinical effective azithromycin formulation with ethanol. In summary, maximum loaded silicas with azithromycin by WIFS is a promising dermal formulation for prophylaxis against Lyme disease.

Azithromycin nanocrystals for dermal prevention of tick bite infections.

Azithromycin was optimized as nanocrystals with a drug content of 10.0 % (w/w) and a surfactant D-α -tocopheryl polyethylenglycol 1000 succinate (TPGS) content of 1.0 % (w/w) using bead milling for 10 min. The photon correlation spectroscopy (PCS) diameter of the bulk population was 189 nm, laser diffraction (LD) diameter 90 % was 370 nm. Spherical morphology of the optimal nanocrystals was observed by transmission electron microscope (TEM). They were stable over 1 year of storage at 4 °C with the particle size within the nanometer range which was confirmed by PCS, LD and light microscope. An acceptable physical stability of 2 years was also obtained when stored at 4 °C. No microbial attack to the nanocrystals was observed before 3 years storage at 4 °C. The saturation solubility of the nanocrystals was up to triple compared to the raw drug powder (RDP) in water. When incorporated into the gel base, highest penetration efficacy was achieved by the optimal nanocrystals compared to 1) the clinically effective ethanol-solution-gel, 2) the gel with propylene glycol and 3) the gel with RDP in the ex vivo porcine ear penetration study. Even though propylene glycol improved saturation solubility of nanocrystals, it could not bring benefit to nanocrystals in the penetration study. Based on these optimized azithromycin nanocrystals, topical administration for enhanced dermal bioavailability of azithromycin seems to be feasible.

Molecular cloning of WIF1 and HMGA2 reveals ear-preferential expression while uncovering a missense mutation associated with porcine ear size in WIF1.

Considerable diversity exists in porcine ear size, which is an important morphological feature of pig breeds. Previously, we localized four crucial candidate genes-high mobility group AT-hook 2 (HMGA2), LEM domain-containing 3 (LEMD3), methionine sulfoxide reductase B3 (MSRB3) and Wnt inhibitory factor 1 (WIF1)-on Sus Scrofa chromosome 5 affecting porcine ear size, then cloned LEMD3 and MSBR3. In this study, we performed rapid amplification of cDNA ends to obtain full-length cDNA sequences of 2338-bp WIF1 and 2998-bp HMGA2. Using quantitative real-time PCR, we revealed that WIF1 expression was highest in ear cartilage of 60-day-old pigs and that this is therefore a better candidate gene for ear size than HMGA2. We further screened coding sequence variants in both genes and identified only one missense mutation (WIF1:c.1167C>G) in a conserved epidermal growth factor-like domain from the mammalian WIF1 protein. The protein-altering mutation was significantly associated with ear size across the Large White×Minzhu hybrid and Beijing Black pig populations. When WIF1:c.1167C>G was included as fixed effect in the model to re-run a genome-wide association study in the Large White×Minzhu intercross population the P-value of the peak SNP on SSC5 from re-running the genome-wide association study dropped from 2.45E-12 to 7.33E-05. Taken together, the WIF1:c.1167C>G could be an important mutation associated with ear size. Our findings provide helpful information for further studies of the molecular mechanisms controlling porcine ear size.

In vitro skin permeation/retention of daidzein, genistein and glycitein from a soybean isoflavone rich fraction-loaded nanoemulsions and derived hydrogels

Positive skin effects have been reported for isoflavones, mainly for their aglycone forms. In this way, the present study addresses the development of products containing isoflavone aglycone-rich fraction (IAF) aimed for dermal application. The formulations investigated were IAF nanoemulsions (NEIAF) and derivative semisolid hydrogels composed of hyaluronic acid (H-NEIAF). The IAF used during this study contained high purity of isoflavone aglycones (IA), obtained after purification of a soybean extract previously hydrolyzed by an enzymatic process. Nanoemulsions (NE) containing 1.0 mg of IA/mL (expressed as sum of genistein, daidzein and glycitein) were prepared, and, in some formulations, hyaluronic acid (3%) was added to obtain hydrogels. Formulations exhibited mean droplet size below to 300 nm and negative ζ-potential. A significant decrease of IA release from formulations was observed when compared to a control (control > NEIAF > HNEIAF). Moreover, after 8 h of permeation/retention in vitro study with porcine ear skin, a significant increase of IA retention was observed from formulations. The distribution of IA in skin layers was evaluated, and the highest IA retention was found in dermis. These results demonstrate the potential of both formulations for topical IA skin applications.

PREPARATION AND CHARACTERIZATION OF GRAPEFRUIT OIL BASE MICROEMULSIONS OF CAFFEINE

Objective: The objective of the present work was to prepare and characterize grapefruit oil base microemulsions loaded with caffeine as a model hydrophilic compound.&#x0D; Methods: The formulation ingredients were selected based on surfactant efficiency and solubility studies. Ternary phase diagrams of grapefruit oil were constructed using the water titration method. Nine O/W microemulsions were constructed and prepared by mixing surfactant system, grapefruit oil, water and caffeine together. The resulting microemulsions were investigated for viscosity using Brookfield viscometer, for pH value using a digital pH meter, and for average particle size and polydispersity index (PDI) using a Zetasizer Nano. Ex vivo skin permeation through porcine ear skin was conducted using a side-by-side diffusion cell. The amount of caffeine was analyzed using HPLC-UV method.&#x0D; Results: Tween 20 yielded the highest emulsification ability for grapefruit oil and the highest caffeine solubility. It was selected as a major surfactant. Caffeine was slightly soluble in ethanol and isopropyl alcohol, but sparingly soluble in propylene glycol (PG). These ingredients were used as the cosurfactants. Nine grapefruit oil base microemulsions were prepared and characterized. The pH of microemulsions was within the range of 4.48-5.96. Particle size was in the range of 10.81±0.03 to 62.18±21.04 µm with the PDI of 0.13±0.02 to 0.64±0.11. Viscosity and particle size of microemulsions increased significantly with increasing grapefruit oil or tween 20 content. Addition of PG as cosurfactant resulted in the increases of viscosity, particle size and PDI. Depending on the formulation parameters, the permeation fluxes of caffeine from grapefruit oil base microemulsions were in the range of 28.4±3.4-361.4±15.2 µg/cm2/h.&#x0D; Conclusion: The grapefruit oil base microemulsions were successfully formulated. The physical properties and caffeine permeation of these microemulsions were found to be dependent on the grapefruit oil content, tween 20 content, cosurfactant type and content, as well as caffeine loading. The optimal formulation of grapefruit oil base microemulsion suggested composition of 5% grapefruit oil, 50% surfactant system (tween 20 and ethanol at the ratio of 9:1), and water.

Experimental studies on the repair and restitution of cartilage by cartilage acellular extracellular matrix and adipose tissue-derived stem cells

Objective: To investigate the effects of the repair and restitution of ear-shaped cartilage by adipose tissue-derived stem cells(ADSC) and cartilage acellular extracellular matrix. Methods: ADSC were extracted by digesting with collagenase type II from the adipose tissue from 32 patients with adiposity whose fats were drawn, and were cultured and subcultured in vitro. The natural biological scaffolds were prepared by acellular method using porcine ear cartilage, and then the second generation ADSC(5.0×10(7)/ml) were inoculated on the preformed natural bio-scaffold scaffold by culturing in vitro for 3 days to form a cell scaffold complex. 32 New Zealand white rabbits were randomly divided into the experimental groups, the control group A, the control group B and the control group C. All New Zealand white rabbits were modeled by ear cartilage defects. The cell scaffolds composite was implanted into the experimental group of the ear cartilage defects of rabbits, the ADSC were implanted into the control group A, the cartilage acellular extracellular matrix scaffold was implanted into the control group B and the control group C was modeled only by ear cartilage defects. After 16 weeks, the animals were sacrificed and the repair effect was observed by gross appearance and histological examinations including HE, Toluidine blue staining, Safranin O and typeⅡ collagen staining. Its were quantitatively analyzed by positive staining results of type Ⅱ collagen. Ear cartilage tissue elasticity was detected. SPSS 17.0 software was used to analyze the data. Results: The cartilage defects in the experimental group were repaired well by general shape observation and those in the control group was filled in with granulation tissue. There were significant differences between the experimental group and the control group in the wet weight(P<0.05). HE staining showed that cartilage cavities formed in articular cartilage defects, and only the fibrous tissue was filled with the ear cartilage defect in the control groups. In the repair area, Toluidine blue staining, Safranin O and type Ⅱ collagen staining were positive in the experimental group, and negative in the control groups. There was no significant difference between the experimental group and the normal ear cartilage in the ear cartilage elastic constant detection(P>0.05). Conclusions: The mechanics and histology of rabbit ear neonatal cartilage constructed by ADSC combined with cartilage acellular matrix are close to normal ear cartilage. Cartilage acellular matrix material combined with adipose-derived stem cells has good repair and reconstruction ability for ear cartilage defects, which possesses potential clinical application value.