Brown R, Gray R H, Bernstein I A
Differentiation. 1985;28(3):268-78. doi: 10.1111/j.1432-0436.1985.tb00835.x.
The effects of vitamin A on the morphological expression of differentiation were studied in cell cultures of cutaneous keratinocytes from the newborn rat. The cells were first cultivated in a medium containing 0.11 mM calcium until a confluent monolayer had been formed. Stratification and terminal differentiation were then triggered by raising the calcium concentration of the medium to 1.96 mM ('normal' culture). The rise in the concentration of calcium was coupled with the addition of retinol (RL) of retinoic acid (RAC) to the medium to produce an excess of vitamin A (high-retinoid culture). Delipidized serum was used to produce a deficiency of vitamin A (low-retinoid culture). The tissue organization and the ultrastructure of the keratinocytes in the stratified culture were the same as those seen in conventional cultures and skin explants. These stratified cultures expressed the morphological features of the epidermis of intact skin. The addition of RL or RAC to the medium enhanced features characteristic of the secretory epithelium, such as the formation of an extensive endoplasmic reticulum, an enlargement of the Golgi zone, and an increase in the number of vacuoles. At the same time, the addition of retinoids diminished features characteristic of the terminal differentiation of the stratified squamous epithelium, such as stratification and keratinization. Deficiency of vitamin A in the medium resulted in a culture with many differentiated layers. The differentiated cells of the low-retinoid cultures contained densely packed tonofilaments and synthesized products that reacted with the monoclonal antibody AE2 that is specific for keratin peptides which are markers of epidermal differentiation. In the cell culture system that is presented here, an excess of retinoids redirected epithelial differentiation from a stratifying and keratinizing epithelium towards a secretory epithelium. This system is a useful tool for elucidating the mechanisms responsible for the effect of vitamin A on the differentiation of epithelial cells.
在新生大鼠皮肤角质形成细胞的细胞培养中，研究了维生素A对分化形态学表达的影响。细胞首先在含有0.11 mM钙的培养基中培养，直至形成汇合的单层。然后通过将培养基中的钙浓度提高到1.96 mM（“正常”培养）来引发分层和终末分化。钙浓度的升高伴随着向培养基中添加视黄醇（RL）或视黄酸（RAC），以产生过量的维生素A（高类维生素A培养）。使用脱脂血清来产生维生素A缺乏（低类维生素A培养）。分层培养的角质形成细胞的组织结构和超微结构与传统培养和皮肤外植体中所见的相同。这些分层培养物表达了完整皮肤表皮的形态特征。向培养基中添加RL或RAC增强了分泌上皮的特征，如广泛内质网的形成、高尔基体区域的扩大和液泡数量的增加。同时，添加类维生素A减少了分层鳞状上皮终末分化的特征，如分层和角化。培养基中维生素A的缺乏导致形成具有许多分化层的培养物。低类维生素A培养物的分化细胞含有密集堆积的张力丝，并合成了与单克隆抗体AE2反应的产物，AE2对角蛋白肽具有特异性，角蛋白肽是表皮分化的标志物。在此呈现的细胞培养系统中，过量的类维生素A将上皮分化从分层和角化上皮转向分泌上皮。该系统是阐明维生素A对上皮细胞分化作用机制的有用工具。
