Improving the Stability of Astaxanthin by Microencapsulation in Calcium Alginate Beads.

There has been considerable interest in the biological functions of astaxanthin and its potential applications in the nutraceutical, cosmetics, food, and feed industries in recent years. However, the unstable structure of astaxanthin considerably limits its application. Therefore, this study reports the encapsulation of astaxanthin in calcium alginate beads using the extrusion method to improve its stability. This study also evaluates the stability of the encapsulated astaxanthin under different storage conditions. The evaluation of astaxanthin stability under various environmental factors reveals that temperature is the most influential environmental factor in astaxanthin degradation. Stability analysis shows that, regardless of the formulation used, the content of astaxanthin encapsulated in alginate beads remains above 90% of the original amount after 21 days of storage at 25°C. These results suggest that the proposed technique is a promising way to enhance the stability of other sensitive compounds.

Rapid-Onset Sildenafil Sublingual Drug Delivery Systems: In Vitro Evaluation and In Vivo Pharmacokinetic Studies in Rabbits.

The aim of the present study was to prepare sublingual delivery systems for sildenafil and evaluate its relative bioavailability after sublingual administration in rabbits to attain a rapid onset of action with good efficacy at lower doses. For sublingual application, sildenafil and its citrate were formulated in 2 different dosage forms: the first was a sublingual spray consisting of sildenafil in 2 microemulsion systems, oleic acid or propylene glycol (PG), and the second was sublingual tablets prepared with various granulated sublingual sprays adsorbed onto a silicate adsorbant (Florite(®) R), binders (Cyclocel(®) or EMDEX(®)), and disintegrants (Ac-Di-Sol(®) or Kollidon(®) CL). Results showed that sublingual absorption of sildenafil spray prepared with PG was fairly rapid. At a 0.5-mg dose, the mean onset of action was 1.3 ± 0.6 min and lasted for about 1.5 h according to the pharmacokinetic studies. In vivo studies also showed that for sublingual tablets formulated with sildenafil in PG adsorbed onto Florite(®) R at a 1:1 weight ratio then mixed with Cycloel(®) and Ac-Di-Sol(®), the onset action was fast at 1.9 ± 0.4 min and lasted for about 1 h at 0.5 mg. These findings suggest the potential for the sublingual delivery of sildenafil instead of the conventional oral administration.

Development and Characterization of Acellular Extracellular Matrix Scaffolds from Porcine Menisci for Use in Cartilage Tissue Engineering.

Given the growing number of arthritis patients and the limitations of current treatments, there is great urgency to explore cartilage substitutes by tissue engineering. In this study, we developed a novel decellularization method for menisci to prepare acellular extracellular matrix (ECM) scaffolds with minimal adverse effects on the ECM. Among all the acid treatments, formic acid treatment removed most of the cellular contents and preserved the highest ECM contents in the decellularized porcine menisci. Compared with fresh porcine menisci, the content of DNA decreased to 4.10%±0.03%, and there was no significant damage to glycosaminoglycan (GAG) or collagen. Histological staining also confirmed the presence of ECM and the absence of cellularity. In addition, a highly hydrophilic scaffold with three-dimensional interconnected porous structure was fabricated from decellularized menisci tissue. Human chondrocytes showed enhanced cell proliferation and synthesis of chondrocyte ECM including type II collagen and GAG when cultured in this acellular scaffold. Moreover, the scaffold effectively supported chondrogenesis of human bone marrow-derived mesenchymal stem cells. Finally, in vivo implantation was conducted in rats to assess the biocompatibility of the scaffolds. No significant inflammatory response was observed. The acellular ECM scaffold provided a native environment for cells with diverse physiological functions to promote cell proliferation and new tissue formation. This study reported a novel way to prepare decellularized meniscus tissue and demonstrated the potential as scaffolds to support cartilage repair.

Wound-healing effect of micronized sacchachitin (mSC) nanogel on corneal epithelium.

The extraction residue of the Ganoderma fruiting body, named sacchachitin, has been demonstrated to have the potential to enhance cutaneous wound healing by inducing cell proliferation. In this study, a nanogel formed from micronized sacchachitin (mSC) was investigated for the potential treatment of superficial chemical corneal burns. Reportedly, mSC has been produced successfully and its chemical properties confirmed, and physical and rheological properties characterized. An in vitro cell proliferation study has revealed that at the concentrations of 200, 300, and 400 microg/mL, mSC nanogel significantly increased Statens Seruminstitut rabbit corneal (SIRC) cell proliferation after 24 hours of incubation. In cell migration assay, migration of SIRC cell to wound closure was observed after 24 hours of incubation with the addition of 200 microg/mL mSC of nanogel. In an animal study, acceleration of corneal wound healing was probably due to the inhibition of proteolysis. In conclusion, the findings of this study substantiate the potential application of sacchachitin in the form of mSC nanogel for the treatment of superficial corneal injuries.

Rapid-onset sildenafil nasal spray carried by microemulsion systems: in vitro evaluation and in vivo pharmacokinetic studies in rabbits.

An oleic acid-based microemulsion system with a member of the Tween series or Cremophor EL as the surfactant and a short-chain alcohol as the cosolvent was developed for rapid-onset intranasal delivery of sildenafil. The phase behaviour and solubilization capacity of the microemulsion system were characterized, and nasal absorption of sildenafil from the microemulsion formulations was investigated in rabbits. Sildenafil displayed a high solubility of 124 mg/mL in the microemulsion consisting of 40% oleic acid, 10% H(2)O, and 50% Tween 80:ethanol (EA) (at a 1:4 weight ratio). Nasal absorption of sildenafil from this microemulsion was found to be fairly rapid. With a 10-mg dose, the onset of action was arrived instantly following intranasal administration and the duration was over 3 h using an in vivo rabbit studies. In addition, nasal ciliotoxicity studies were carried out using in vivo rat nasal mucosa model and showed no ciliotoxicity. Therefore, the prepared systems are no serious nasal ciliotoxicity for intranasal administration. The microemulsion system composed of oleic acid, Tween 80, EA, and water may be a practical approach for the rapid-onset delivery of sildenafil for the treatment of erectile dysfunction.

Development of swelling/floating gastroretentive drug delivery system based on a combination of hydroxyethyl cellulose and sodium carboxymethyl cellulose for Losartan and its clinical relevance in healthy volunteers with CYP2C9 polymorphism.

The aim of this study was to develop an optimal gastroretentive drug delivery system (GRDDS) for administering Losartan. Additionally, the influence of optimized GRDDS on the bioavailability of Losartan and the formation extent of active metabolite E3174 by CYP2C9 polymorphism was investigated. Swellable and floatable GRDDS tablets combining hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (NaCMC), and sodium bicarbonate were prepared at various compression pressures for evaluating swelling characteristics and floating capacity. Then Losartan was incorporated into optimized formulations for in vitro and in vivo characterizations. An appropriate ratio of HEC to NaCMC, addition of sodium bicarbonate, and compression at lower pressures resulted in the tablets floating over SGF for more than 16 h and swelling to 2 cm in diameter within 3h. The release patterns of Losartan from these tablets were pH-dependent. Results of the clinical trials showed that the mean bioavailability from GRD-A (HEC 91.67%, sodium bicarbonate 3.33% and Losartan 8.33%) was approximately 164%, relative to the immediate-release product (Cozaar). MRT and t(max) values were greater and C(max) values were lower for the GRDDS tablets compared with Cozaa. The lower bioavailability of Losartan in the CYP2C9*1/*1 subjects than CYP2C9*1/*3 subjects was found and could be due to the variety of enzymatic activity.

Development of N,O-(carboxymethyl)chitosan/collagen matrixes as a wound dressing.

In an attempt to accelerate wound healing by stimulating the recruitment of fibroblasts and improve the mechanical properties of collagen matrixes, N,O-(carboxymethyl)chitosan (NOCC) was incorporated into the backbone of a collagen (COL) matrix without or with chondroitin sulfate (CS) or an acellular dermal matrix (ADM). The result of a cell migration study demonstrated that the migration of fibroblasts was significantly enhanced by NOCC in a concentration-dependent manner. In the analysis with a dynamic mechanical analyzer, NOCC/CS/COL matrixes presented higher tensile strengths than did NOCC/ADM/COL matrixes. Skin fibroblasts cultured on the matrixes containing NOCC showed increased proliferation and secretion of three kinds of cytokines compared with the control. Results of the in vivo wound healing study showed that matrixes incorporating NOCC showed markedly enhanced wound healing compared with the control. Therefore, the above results clearly suggest that NOCC/COL matrixes containing CS or ADM can be potential wound dressings for clinical applications.

Characterization of collagen matrices crosslinked using microbial transglutaminase.

In search of a new approach for crosslinking collagen-based biomaterials, we examined the effect of microbial transglutaminase (MTGases) as a crosslinking reagent on collagenous matrices made from porcine type I collagen. As the results revealed, MTGase exhibited a crosslinking action that raised the viscosity of the collagen solution. Matrices crosslinked with MTGase at the low pH values of pH 3 and 4 exhibited higher tensile strengths than those at high pH values. In comparison with untreated matrices, the denaturation temperatures of the corresponding matrices shifted toward higher temperatures. These enzyme-catalyzed crosslinked matrices were proven by MTT assay to be non-cytotoxic. In conclusion, this enzymatic method of using MTGase provides an alternative potential way for crosslinking collagen-based matrices.

Viscoelastic characterizations of acellular dermal matrix (ADM) preparations for use as injectable implants.

Viscoelastic characteristics of acellular dermal matrix (ADM) preparations with various additives were analyzed with creep curves, stress-strain relationships, and the storage modulus with reference to those of ADM preparations crosslinked with glutaraldehyde. Creep curves for all ADM preparations were determined to comply with the Kelvin-Voigt model. The stress-strain plots of all ADM preparations compared were described as linear. The storage modulus of all ADM preparations was maintained at a nearly constant level throughout the range of oscillating frequencies applied. ADM preparations crosslinked with glutaraldehyde showed that both Young's modulus (E) for the spring part and retardation time (tau) in the Kelvin-Voigt model, and hence viscosity (eta) for the liquid part, increased with an increasing concentration of glutaraldehyde. Higher Young's modulus and viscosity and a greater extent of the "solid" response of ADM preparations crosslinked with glutaraldehyde might have been responsible for the longer persistence that was demonstrated after implantation. The increase in ADM concentration and the addition of various additives to ADM preparations, including alpha-hydroxy acid (citric acid, lactic acid, and glycolic acid) and hyaluronic acid, resulted in similar effects on the viscoelastic characteristics of the ADM preparations, but they were less efficacious than those crosslinked with glutaraldehyde. Among them, increasing ADM concentration to >200 mg/mL and addition of glycolic acid at a concentration of >2% improved the viscoelastic characteristics of the resulting ADM preparations so that their level of persistence was closer to that of material crosslinked with glutaraldehyde. On the contrary, the influence on viscoelastic characteristics of adding PVP greatly differed from that of hyaluronic acid and was only apparent when adding concentrations of PVP of >10%. Similarly, viscoelastic characteristics of the ADM preparations examined were also so sensitive to temperature that the persistence of ADM preparations after implantation at body temperature would deteriorate.

Process development of an acellular dermal matrix (ADM) for biomedical applications.

The object of this study was to compare the extent of decellularization at each critical step of processing porcine skin to produce an acellular dermal matrix (ADM) for biomedical applications. The results demonstrated that the removal of epidermis using treatment with 0.25% trypsin for 18 h and 0.1% sodium dodecyl sulfate (SDS) for 12 h at room temperature was beneficial for the subsequent treatment to remove cells in the dermal structure. Lengthy incubation in 0.25% trypsin (12 h) and then 560 units/l Dispase (12 h) at 25 degrees C of small pieces of porcine skin from which the epidermis had been removed efficiently removed cells and cellular components from the skin. Histological examinations revealed that the epidermis, dermal fibroblasts, and epidermal appendages were completely removed by these treatments, and the basic dermal architecture of collagen bundles was that of a loose meshwork. Examinations by TEM showed that the characteristics of collagen fibers in the ADM were retained after complete removal of cells present under optimal conditions defined in this study. SDS-PAGE and size-exclusion HPLC revealed that collagen fibers in the ADM were mostly type I and showed two typical component peaks identified as oligomers and monomers, respectively.