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Ultra-deformable liposomes containing bleomycin: in vitro stability and toxicity on human cutaneous keratinocyte cell lines |
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| Authors: | Lau Kent G Hattori Yoshiyuki Chopra Sunil O'Toole Edel A Storey Alan Nagai Tsuneji Maitani Yoshie |
| Affiliation: | aInstitute of Medicinal Chemistry, Hoshi University, Ebara 2-4-41, Shinagawa-Ku, Tokyo 142-8501, Japan bDepartment of Dermatology, King George Hospital, Barley Lane, Essex IG3 8YB, UK cCentre for Cutaneous Research, Institute of Cell and Molecular Sciences, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, 2 Newark Street, London E1 2AT, UK dCancer Research UK Skin Tumour Laboratory, Institute of Cell and Molecular Sciences, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, 2 Newark Street, London E1 2AT, UK |
| Abstract: | Formulations of ultra-deformable liposomes containing bleomycin (Bleosome™) have previously been described and proposed for topical treatment of skin cancer [Lau, K.G., Chopra, S., Maitani, Y., 2003. Entrapment of bleomycin in ultra-deformable liposomes. S. T. P. Pharm. Sci. 13, 237–239]. In this study, the stability of various Bleosome™ formulations was characterised and a purification process was established to isolate Bleosome™ for testing on cultures of either human cutaneous keratinocytes (NEB-1) immortalised by human papilloma virus (HPV)-type 16, or a spontaneously immortalised human squamous cell carcinoma (SCC) from a primary tumour. Bleosome™ facilitated entrapment of high concentrations of active bleomycin and samples purified by gel-filtration chromatography remained stable during 7 days of storage at 4 °C or at room temperature. Serially-diluted samples of this purified, high-strength product, ‘high dose’ were applied onto keratinocyte cell cultures to elucidate Bleosome™ LD50 profiles. In vitro data revealed that the LD50 of bleomycin encapsulated in Bleosome™ was approximately three-fold higher than free bleomycin solution for SCC cells, and nearly 30 times higher for NEB-1 cells. However, Bleosome™ containing 30 μg/ml of active bleomycin killed more than twice as many SCC cells than NEB-1 cells. At that concentration, the potency of liposomal bleomycin on causing cell death of SCC cells was found to be similar to that of free bleomycin solution. This effect was not seen on NEB-1 cells. It seems that SCC cells were particularly susceptible to Bleosome™ containing high levels of bleomycin. Results from these experiments promote the development of a novel product for the topical treatment of skin cancer. |
| Keywords: | Ultra-deformable liposome Bleomycin Keratinocyte cell Squamous cell carcinoma Toxicity In vitro stability |
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