Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone,
cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue
regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial
for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and
photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by
developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the
nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and
correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force
Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive
manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin
fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and
image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells
behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better
understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing
biomaterials.
In this paper the cytotoxic effect of m-THPC, Foscan®, as well as of the liposomal formulation of m-THPC, Fospeg®,(kind offer of Biolitec) were studied post PDT in the human prostate cancer cell line LNCaP. The cells were incubated for 24h with 0.15 μg/ml and 1.2 μg/ml Foscan® and Fospeg®. Irradiation was performed with a 652nm laser and energy doses 180, 360 and 540mJ/cm2. The effect was assessed by the MTT viability test 24h after irradiation. Also the intracellular localization of Foscan® and Fospeg® was monitored by using Laser Scanning Confocal Microscopy Imaging. The results showed no dark toxicity either with Foscan® or
Fospeg® at any concentration. Also irradiation at each energy dose in the absence of any photosensitizer, did not affect cellular
viability. The cellular death caused after Photodynamic Treatment was dependent on m-THPC concentration and formulation, as well as the delivered energy dose. Fospeg® was more effective as LD50 was achieved with 0.15μg/ml at 180mJ/cm2 while for the same cytotoxic result 1.2μg/ml Foscan® was needed. Images from confocal microscopy revealed higher fluorescence intensity in the cytoplasm after incubation with Fospeg®, than upon incubation with Foscan® under the same experimental conditions.
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