Design of shark skin collagen-aloe composite scaffold for tissue engineering

Se ha demostrado que el colágeno es un nuevo biomaterial utilizado para la administración de fármacos, la fabricación de apósitos o como sustrato para ingeniería tisular cuya biocompatibilidad y propiedades biodegradables son únicas. El colágeno bovino y porcino tipo I constituyen una fuente fácilmente disponible de material de soporte para diversas aplicaciones biomédicas. Sin embargo, estas fuentes conllevan cierto riesgo potencial de enfermedades infecciosas como la encefalopatía espongiforme bovina o la encefalopatía espongiforme transmisible. Por esta razón, existe una demanda de colágeno tipo I procedente de otras fuentes. En el presente estudio, se utilizan animales acuáticos y, en concreto, especies de tiburón en las que el colágeno tipo I es una proteína principal de la piel y la estructura tiene similitud con la de las especies mamíferas. Se ha intentado utilizar colágeno de piel de tiburón como matriz de soporte con extracto de aloe para mejorar la estabilidad. Estas matrices de soporte se caracterizaron por varias propiedades fi sicoquímicas y por la evaluación de biocompatibilidad para facilitar el crecimiento de fi broblastos dérmicos humanos in vitro. La incorporación de extracto de aloe infl uyó enormemente en la morfología y las propiedades fi sicoquímicas de la matriz de soporte. Se observó in vitro que los fi broblastos conservaban la orientación organizada en forma de huso al cultivarse sobre la matriz de soporte de colágeno. Así, la matriz de soporte de colágeno desarrollada con una proporción de 10:1 de colágeno de piel de tiburón y extracto de aloe, respectivamente, sirvió como material biocompatible con una resistencia a la tracción apreciable. La investigación anterior sugiere que la matriz de soporte de colágeno de piel de tiburón desarrollada puede ser una alternativa efectiva al colágeno de mamífero en el campo de la ingeniería tisular y para diversas aplicaciones en la curación de heridas.Collagen has proven to be a novel biomaterial used for drug delivery, wound cover dressings or as a substrate for tissue engineering with unique biocompatibility and biodegradable properties. Bovine and porcine Type I collagen provide a readily available source of scaffold material for various biomedical applications. However these sources have some potential risk of infectious diseases such as bovine spongiform encephalopathy or transmissible spongiform encephalopathy. Hence there is demand for an alternative Type I collagen from various other sources. The present study utilizes the aquatic animals particularly the shark species in which collagen Type I is a major protein in the skin and the structure has similarity to that of mammalian species. An attempt was made to use shark skin collagen as scaffold with the extract of aloe to improve the stability. These scaffolds were characterized for various physicochemical properties and biocompatibility assessment to support the growth of human dermal fi broblasts in vitro. The incorporation of aloe extract highly infl uenced the morphology and physicochemical properties of the scaffold. It was observed in vitro that the fi broblasts retained the spindle shape, organized orientation when cultured over collagen scaffold. Thus the developed collagen scaffold at 10: 1 ratio of shark skin collagen and aloe extract respectively served as a biocompatible material with appreciable tensile strength. The above investigation suggests that the developed shark skin collagen scaffold could be an effective alternative for the mammalian collagen for tissue engineering and various wound healing applications

Wound dressings for a proteolytic-rich environment

Wound dressings have experienced continuous and significant changes over the years based on the knowledge of the biochemical events associated with chronic wounds. The development goes from natural materials used to just cover and conceal the wound to interactive materials that can facilitate the healing process, addressing specific issues in non-healing wounds. These new types of dressings often relate with the proteolytic wound environment and the bacteria load to enhance the healing. Recently, the wound dressing research is focusing on the replacement of synthetic polymers by natural protein materials to delivery bioactive agents to the wounds. This article provides an overview on the novel protein-based wound dressings such as silk fibroin keratin and elastin. The improved properties of these dressings, like the release of antibiotics and growth factors, are discussed. The different types of wounds and the effective parameters of healing process will be reviewed

Macrophage-Specific Targeting of Isoniazid Through Mannosylated Gelatin Microspheres

Active targeting of drug molecules can be achieved by effective attachment of suitable ligands to the surface of carriers. The present work was attempted to prepare mannosylated gelatin microspheres (m-GMs) so as to achieve targeted delivery of isoniazid (INH) to alveolar macrophages (AMs) and maintain its therapeutic concentration for prolonged period of time. Microspheres were prepared by emulsification solvent extraction method and evaluated for physicochemical characteristics, drug release, ex vivo drug uptake by AMs and pharmacokinetic characteristics. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectral analysis confirmed that mannosylation took place through Schiff base formation between aldehyde and amino groups of mannose and gelatin, respectively. Prepared microspheres offered suitable physicochemical characteristics for their delivery to AMs. Their average size was about 4 μm and drug entrapment efficiency of 56% was achieved with them. Ex vivo uptake results indicated that in comparison to plain microspheres, m-GMs were selectively uptaken and were found to be associated with phago-lysosomal vesicles of AMs. Pharmacokinetic studies showed the formulation could maintain the therapeutic concentration of INH for prolonged period of time even with a reduced clinical dose. m-GMs were found to be stable in broncheo-alveolar lavage fluid. The study concluded that ligand decorated carriers could be a potential strategy to improve the therapeutic properties of INH