Umegaki Ryota, Murai Koji, Kino-Oka Masahiro, Taya Masahito
Department of Chemical Science and Engineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan.
J Biosci Bioeng. 2002;94(3):231-6. doi: 10.1263/jbb.94.231.
In serial cultures of keratinocytes isolated from human neonatal foreskin, the potential for cell attachment and cell division decreased with an increase in the number of culture passages. The specific growth rate of the cells (mu) reduced gradually with elapsed culture time and an appreciable drop in the rate was observed below mu=0.02 h(-1) owing to cellular senescence. Then, a critical point in the serial cultures was determined as the last data point keeping the mu value at more than 0.02 h(-1). In serial cultures of keratinocytes isolated from the breast skin of 22 and 70-year-old individuals, the time profiles of the mu value displayed critical points, as observed in the neonatal foreskin cultures. Plots of the mu value and average cell area against the remaining numbers of population doublings (N(dF)/t-N(d)) were found to give a relationship which overlapped irrespective of the three kinds of keratinocytes, and the propensity for a depression of growth potential [estimated as a ratio of differential value of mu to that of (N(dF)-N(d))] was much higher after the critical point than before. In addition, a data map in terms of the specific growth rate and average cell area, which could be classified into proliferative, senescent and transitional phases, was proposed for the discrimination of cellular senescence in serial cultures for the production of epithelial sheets.
在从人新生儿包皮分离的角质形成细胞的连续培养中，细胞附着和细胞分裂的潜能随着传代次数的增加而降低。细胞的比生长速率（μ）随着培养时间的推移逐渐降低，并且由于细胞衰老，在μ = 0.02 h⁻¹以下观察到速率明显下降。然后，将连续培养中的临界点确定为使μ值保持在0.02 h⁻¹以上的最后一个数据点。在从22岁和70岁个体的乳房皮肤分离的角质形成细胞的连续培养中，μ值的时间曲线显示出临界点，如在新生儿包皮培养中所观察到的。发现μ值和平均细胞面积相对于剩余群体倍增数（N(dF)/t - N(d)）的图给出了一种与三种角质形成细胞无关的重叠关系，并且在临界点之后生长潜能降低的倾向[估计为μ的差值与（N(dF) - N(d)）的差值之比]比之前高得多。此外，提出了一个根据比生长速率和平均细胞面积的数据图，该图可分为增殖期、衰老期和过渡期，用于在连续培养中生产上皮片时鉴别细胞衰老。
