Electrophoretic mobility of corneocytes measured by laser Doppler spectroscopy

A new approach studying the characteristics of the stratum corneum is presented: the electrophoretic mobility of corneocytes by laser Doppler spectroscopy. The detergent scrub technique was used for harvesting corneocytes from three body regions (forehead, palm, and sole) of normal persons (n = 20) under casual conditions and after thorough defattening of the skin with 70% isopropyl alcohol or petrol. Similarly, cells from the forehead, shoulder, and palm were obtained from 22 acne patients treated with isotretinoin (13-cis retinoic acid) 0.5-0.7 mg/kg body weight (b.wt.)/day for 12-16 weeks, and in patients receiving arotinoid (Ro 15-0778) 192 mg (n = 5) or 500 mg (n = 5) per kg/b.wt./day for 6 weeks (forehead and shoulder). In another experiment, cell suspensions with a pH ranging from 5.0-7.3 were evaluated. Measurements were performed by dynamic laser light scattering. This laser application allows exact electrophoretic mobility measurements in a short time (3 min). When cells pass the laser beam, the scattered light is frequency-shifted due to the optical Doppler effect. These frequency shifts are analyzed by the heterodyne light beating technique. The analog signal of the photodetector is converted into a power spectrum by Fourier analysis. This power spectrum represents the spectrum of electrophoretic cell mobility distribution. Results showed different electrophoretic mobility values for corneocytes dependent on the topographic region: forehead 1.18 +/- 0.16, palm 1.10 +/- 0.14, and sole 0.83 +/- 0.10 (means +/- SEM) micron cm/Vs. Defattening with isopropyl alcohol decreased the mobility values to 0.90 +/- 0.09 (p less than or equal to 0.01), 0.95 +/- 0.10, and 0.77 +/- 0.10 micron cm/Vs respectively.(ABSTRACT TRUNCATED AT 250 WORDS)