Microneedle-mediated intradermal delivery of 5-aminolevulinic acid: potential for enhanced topical photodynamic therapy

Photodynamic therapy of deep or nodular skin tumours is currently limited by the poor tissue penetration of the porphyrin precursor 5-aminolevulinic acid (ALA). In this study, silicon microneedle arrays were used, for the first time, to enhance skin penetration of ALA in vitro and in vivo. Puncturing excised murine skin with 6x7 arrays of microneedles 270 mum in height, with a diameter of 240 mum at the base and an interspacing of 750 mum led to a significant increase in transdermal delivery of ALA released from a bioadhesive patch containing 19 mg ALA cm(-2). Microneedle puncture enhanced ALA delivery to the upper regions of excised porcine skin but, at mean depths of 1.875 mm, ALA concentrations were similar to control values, possibly reflecting binding of ALA by tissue components. However, and importantly, in vivo experiments using nude mice showed that microneedle puncture could reduce application time and ALA dose required to induce high levels of the photosensitiser protoporphyrin IX in skin. This clearly has implications for clinical practice, as shorter application times would mean improved patient and clinician convenience and also that more patients could be treated in the same session. As ALA is expensive and degrades rapidly via a second order reaction, reducing the required dose is also a notable advantage.

The tissue plasminogen activator gene promoter: a novel tool for radiogenic gene therapy of the prostate?

Radiation therapy is a treatment modality routinely used in cancer management so it is not unexpected that radiation-inducible promoters have emerged as an attractive tool for controlled gene therapy. The human tissue plasminogen activator gene promoter (t-PA) has been proposed as a candidate for radiogenic gene therapy, but has not been exploited to date. The purpose of this study was to evaluate the potential of this promoter to drive the expression of a reporter gene, the green fluorescent protein (GFP), in response to radiation exposure. METHODS: To investigate whether the promoter could be used for prostate cancer gene therapy, we initially transfected normal and malignant prostate cells. We then transfected HMEC-1 endothelial cells and ex vivo rat tail artery and monitored GFP levels using Western blotting following the delivery of single doses of ionizing radiation (2, 4, 6 Gy) to test whether the promoter could be used for vascular targeted gene therapy. RESULTS: The t-PA promoter induced GFP expression up to 6-fold in all cell types tested in response to radiation doses within the clinical range. CONCLUSIONS: These results suggest that the t-PA promoter may be incorporated into gene therapy strategies driving therapeutic transgenes in conjunction with radiation therapy.

Compression therapy in leg ulcer management

Led ulcer management is an important consideration for all nurses involved in the care of older people. Non-specialists in tissue viability might not always be aware of the evidence base for best practice. The authors examine the effectiveness of multi-layer and single-layer long or short stretch bandage systems in leg ulcer management.