Needle-free cutaneous delivery of living human cells by Er:YAG fractional laser ablation

Background: Dermatological diseases, including most skin cancers and rare genetic conditions frequently originate in the epidermis. Targeted, topical cell-based therapy is a promising therapeutic strategy. Here, we present the first report demonstrating that fractional laser ablation enables local needle-free' intraepidermal delivery of living human cells. Methods: The cells penetrated porcine ear skin via microchannels created by Er:YAG fractional laser ablation; cell delivery was quantified using a haemocytometer. Cutaneous distribution was confirmed visually by laser scanning confocal microscopy and histological analysis. Results: Total cell delivery (sum of amounts permeated and deposited) after 24h increased from 5.7 +/- 0.1 x 10(5) to 9.6 +/- 1.6 x 10(5)cells/cm(2) when increasing pore density from 300 to 600pores/cm(2), - corresponding to 19- and 32-fold increases over the control. At 600pores/cm(2), cell deposition was 136-fold greater than cell permeation - the latter most likely due to transport from micropores into appendageal pathways. Production of GFP post-delivery confirmed cell remained viability. Conclusion: The results demonstrate the feasibility of using controlled laser microporation to achieve local needle-free' cutaneous delivery of living human cells to the epidermis and dermis. This raises the possibility of using this technique for targeted new approaches for dermatological therapy in these regions.