Drug permeability in tissue engineered models and cytotoxicity evaluations

This dissertation is a compilation of studies at both the cellular and in vitro tissue levels. It explores the in vitro chemo- and photo-toxicity of compounds - fractionated melanin (Mel-HEV) and chlorpromazine (CPZ) - in two human cell lines – HDF and HEKn and compares the effects to mouse fibroblast cell line ‘Balb/c 3T3’, cell line recommended by the European Center of Validation of Alternative Methods (ECVAM). The cell lines Balb/c 3T3 and HEKn were found sensitive to the phototoxic potential of CPZ. However, HDF showed insensitivity to phototoxic evaluation. The test compound, Mel-HEV, was found to be non-phototoxic. Following the cellular toxicity studies, the dissertation progresses into the understanding the permeation analysis of Naltrexone HCL (NTXHCL) across tissue engineered buccal and skin membranes. The effects of two surfactants (Brij 58® and Tween 80®) and changes in solution pH on in vitro permeation of NTX were observed. It was observed that the flux of 10mg/ml NTX solution (pH 6.8) increased from 1.9 ± 0.6 (×102) to 13.9 ± 2.2 (×102) μg/cm2/h (approximately 6 fold) in presence of 1% Brij 58®. Increasing pH of NTX-HCl solution was found to increase the drug flux from 1.9 ± 0.6 (×102) (pH 6.8) to 3.0 ± 0.6 (×102) (pH 7.4) and 8.0 ± 3.5 (×102) (pH 8.2) μg/cm2/h respectively. In tissue engineered human skin studies, a novel full thickness Human Skin Equivalent (HSE) containing a polymer electrospun mesh in the dermal component was developed and tested for mechanical strength comparative to currently available collagen based HSE, human and porcine skin. A comparison of its morphology and permeability characteristics with ex vivo human and porcine skin was also performed. The mean Young’s modulus of polymeric HSE (0.4 ± 0.3 MPa) was found similar to that of excised human skin (0.5 ± 0.1 MPa), much higher than of collagen HSE (0.009 ± 0.009 MPa). The histological sections of polymeric HSE have been shown to exhibit well-formed dermal and fully differentiated epidermal layers. Polymeric HSE exhibited barrier properties which are comparatively weaker than those of ex vivo human/pig tissues but comparable to the commercially available model (Epiderm FT®).Ph. D.Includes bibliographical referencesIncludes vitaby Vishwas Ra