The Characteristics of Proliferation and Differentiation of Psoriatic Keratinocytes in Culture

Kim, Hyun Seok; Shin, Dong Hoon; Choi, Jong Soo; Kim, Ki Hong; Kim, Mi Jin; Kim, Seong Yong; Sung, Eon Ki

Abstract

BACKGROUND: Psoriasis is a common, scaly erythematous disease of unknown etiology, marked by remissions and exacerbations of unpredictable onset and duration. Among many etiologic factors, psoriatic keratinocyte is found to play the most important role.
OBJECTIVE
The purpose of this study is to evaluate the hypothesis that the mechanism(s) responsible for the abnormal proliferation of psoriatic keratinocytes may be located within the cell themselves.
METHODS
Human epidermal keratinocytes were isolated from lesion(PL) and from uninvolved skin (PN) with chronic plaque-like psoriasis and from the normal skin(NN). Keratinocytes were passaged onto culture vessels without the feeder layer and maintained with serum free medium. Growth rates were measured in secondary cultures by MTT assay and ultrastructural findings of cell differentiation were evaluated with a transmission electron microscope.
Results
: 1 Keratinocytes from PL reached 50% confluency in one week compared to two weeks of PN and NN in primary cultures. 2. By the MTT assay, keratinocyte proliferation from PL showed a significantly faster rate than those from PN and NN(p<0.01). But there was no significant difference of keratinocyte proliferation rate between PN and NN(p>0.05). 3. All of the three cell populations(PL, PN, NN) showed variable degrees of cell differentiation during secondary culturing in a serum-free medium. In the PL, however, small, compact basal cells were more prevalent than PN and NN. 4. When keratinocytes underwent differentiation by culturing in DMEM with serum, keratinocytes from PL formed more cell layers with incomplete formation of cornified envelopes suggests the presence of some unknown factors that induce or promote psoriasis. While keratinocytes from PN and NN were characterized by a complete codified layer as in normal skin.
Conclusion
: These results indicated that the characteristic hyperproliferation and the defective terminal differentiation of keratinocytes of PL were maintained throughout the culture period.