Functionally modified gelatin microspheres impregnated collagen scaffold as novel wound dressing to attenuate the proteases and bacterial growth.

An attempt was made to develop a new therapeutic delivery system which would play a dual role of attenuating MMP activity in the wounds and also prevent infection by controlled delivery of antimicrobials. A catechol type MMP inhibitor 2,3-dihydroxybenzoic acid (DHBA) was conjugated to gelatin microspheres using EDC/NHS as coupling agents. The potential of the modified gelatin microspheres (DHB-MS) to attenuate the proteases such as MMP 2 and MMP 9 in the diabetic wound tissues was investigated by gelatin zymography. Further the modified microspheres were loaded with doxycycline and impregnated in a reconstituted collagen scaffold as novel wound dressing. The in vitro release behavior of doxycycline from both DHB-MS and DHB-MS impregnated collagen scaffold was investigated. DHB-MS when incubated with the tissue lysate for 6h displayed the complete inhibition of the MMPs in the tissue lysate. The in vitro drug release studies from the collagen scaffold exhibited the burst release of 44%, exerted immediate chemo prophylaxis and sustained delivery for 72 h. The MTT assay and fluorescent labeling with calcein AM indicated that the DHB-MS is biocompatible to human foreskin fibroblasts. Thus the system developed provides wider scope to control the pathogens involved in infection and also the excess matrix degradation.

Diseño de una matriz de soporte compuesta de colágeno de piel de tiburón-aloe para ingeniería tisular / 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 fisicoquímicas y por la evaluación de biocompatibilidad para facilitar el crecimiento de fibroblastos dérmicos humanos in vitro. La incorporación de extracto de aloe influyó enormemente en la morfología y las propiedades fisicoquímicas de la matriz de soporte. Se observó in vitro que los fibroblastos 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 (AU)

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 fibroblasts in vitro. The incorporation of aloe extract highly influenced the morphology and physicochemical properties of the scaffold. It was observed in vitro that the fibroblasts 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 (AU)

Gelatin microspheres cross-linked with EDC as a drug delivery system for doxycyline: development and characterization.

Chronic wounds express elevated levels of proteases, in particular matrix metalloproteinases (MMPs), which degrades de novo granulation tissue and endogenous biologically active proteins. An effective therapeutic approach for chronic wounds would be to modify this hostile environment and reduce the proteolytic imbalance. Doxycycline has been proved recently to inhibit MMPs and used topically for chronic wound ulcers, beyond their antimicrobial profile. To this end, a carrier system for controlled release of doxycycline, suitable for incorporation into various wound dressings like membranes and sponges was developed. In the present study gelatin microspheres, cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) was proposed. The cross-linking was carried out with different concentrations of EDC (10 mM, 50 mM and 100 mM) and for different time periods (3-24 h). The cross-linked microspheres were characterized by evaluating the extent of cross-linking, the morphology, swelling behaviour and drug loading and in vitro studies of drug release, enzymatic degradation and biocompatibility. The extent of cross-linking increased as a function of both EDC concentration and the cross-linking time periods. It is found that the extent of cross-linking greatly influences the swelling and drug release behaviour of the microspheres. The cross-linked microspheres were found to be biocompatible to NIH 3T3 mouse embryonic fibroblast. The overall study indicates that the zero length cross-linker EDC can be considered as a potential alternative for cross-linking the gelatin microspheres.

In vivo and in vitro evaluation of hair growth potential of Hibiscus rosa-sinensis Linn.

Petroleum ether extract of leaves and flowers of Hibiscus rosa-sinensis was evaluated for its potential on hair growth by in vivo and in vitro methods. In vivo, 1% extract of leaves and flowers in liquid paraffin was applied topically over the shaved skin of albino rats and monitored and assessed for 30 days. The length of hair and the different cyclic phases of hair follicles, like anagen and telogen phases, were determined at different time periods. In vitro, the hair follicles from albino rat neonates were isolated and cultured in DMEM supplemented with 0.01 mg/ml petroleum ether extract of leaves and flowers. From the study it is concluded that the leaf extract, when compared to flower extract, exhibits more potency on hair growth.