Cell Cycle Kinetics of Human Anagen Scalp Hair Bulbs in Thyroid Disorders Determined by DNA Flow Cytometry

Abstract

In both, 6 hyperthyroid and 6 hypothyroid patients as well as 10 healthy volunteers, cell cycle kinetics of dissected anagen scalp hair bulbs were determined by means of DNA flow cytometry (DNA-FCM). Compared with the healthy control group in patients with thyroid disorders striking differences of cell kinetic data were evaluated. In hyperthyroidism a significant increase (30%) and in hypothyroidism a significant decrease (15%) of S and G₂ + M phase cell percentages was found. The proliferation index (S + G₂ + M%) calculated revealed similar results. A correlation between the height of S phase percentages and plasma T₃ levels was recognizable but could not be proved statistically. By means of DNA-FCM the study demonstrates for the first time the influence of thyroid hormones on in vivo cell cycle kinetics of human scalp hair bulbs.

Thyroid Hormones Directly Alter Human Hair Follicle Functions: Anagen Prolongation and Stimulation of Both Hair Matrix Keratinocyte Proliferation and Hair Pigmentation

“…Our demonstration that addition of exogenous TH to human HFs cultured in the absence of systemic TH prolongs anagen and stimulates hair matrix keratinocyte proliferation and inhibits their apoptosis provides the first direct evidence for the validity of this old postulate. Our findings also fit well with the reportedly increased hair matrix proliferation in hyperthyroid patients in vivo (3). Unfortunately, amputated, organcultured human scalp anagen VI hair bulbs do not run through full cycles in vitro and decay shortly after catagen development (30,(37)(38)(39).…”

“…HFs were washed several times and cultured for 48 h. Serum-free supernatant was collected for the analysis. The sensitivity of the assays was 0.260 pg/ml (0.400 pmol/liter) for fT 3 and 0.23 pg/ml (0.30 pmol/liter) for fT 4 .…”

Thyroid Autoimmunity in Patients with Skin Disorders

“…Massive telogen effluvium may occur when there is abrupt onset of hypothyroidism, and the percentage of scalp hairs in telogen is generally increased in hypothyroid states [10]. Using DNA flow cytometry, Schell et al observed that cell proliferation indices were reduced in hair bulbs of hypothyroid subjects and increased in hyperthyroidism compared with normal values [13]. Hypothyroid patients, especially children, frequently develop long, lanugo-type hair on the back, shoulders, and extremities [10].…”

Thyroid hormone action on skin

“…DNA flow cytometry studies of dissected anagen hairs from thyrotoxic patients (compared with follicles taken from euthyroid controls) demonstrated a 30% increase in the S and G 2 + M phases of the cell cycle. 52 However, like with epidermal proliferation, hair changes with thyrotoxicosis are different than what can be effected with topically administered thyroid hormone. Mice and rats treated daily for 1-2 weeks with topical T 3 had increased hair counts but mice made thyrotoxic with daily intraperitoneal T 3 for 1-2 weeks had decreased hair counts.…”