van den Aardweg G J, Morris G M, Bywaters A, Bakker E J, Mooi W J
Department of Radiation Oncology, University Hospital Rotterdam-Daniel den Hoed Cancer Center/Dijkzigt Hospital, Josephine Nefkens Institute, PO Box 1738, 3000 DR Rotterdam, The Netherlands.
Br J Radiol. 2001 May;74(881):434-44. doi: 10.1259/bjr.74.881.740434.
Epidermal clonogenic cell survival and colony formation following irradiation were investigated and related to radiosensitivity. A rapid in vivo/in vitro assay was developed for the quantification of colonies arising from surviving clonogenic cells in pig epidermis after irradiation. Bromodeoxyuridine (BrdU)-labelled cells in full thickness epidermal sheets were visualized using standard immunohistochemistry. In unirradiated skin, approximately 900 BrdU-positive cells mm(-2) were counted. In a time sequence experiment, BrdU-positive cell numbers increased from an average of 900 cells mm(-2) to approximately 1400 cells mm(-2) after BrdU-labelling for 2-24 h. In irradiated skin, colonies containing >/=16 BrdU-positive cells were seen for the first time at days 14/15 after irradiation. The number of these colonies per cm(2) as a function of skin surface dose yielded a cell survival curve with a D(0)-value (+/-SE) of 3.9+/-0.6 Gy. This relatively high D(0)-value is possibly due to a rapid fall off in depth dose distribution for the iridium-192 source and consequently a substantial contribution of hair follicular epithelium to colony formation. At 14/15 days after irradiation, the ED(50) level of 33.6 Gy for the in vivo response of moist desquamation corresponded with 2.7 colonies cm(-2). Surprisingly, the number of colonies increased with time after irradiation with an estimated doubling time of approximately 4 days, while the D(0)-value remained virtually unchanged. This increase in colony numbers could be due to migration of clonogenic cells, to the recruitment of dormant clonogenic cell survivors by elevated levels of cytokines, or to both. Although frequent biopsying caused increased cytokine levels, which had a systemic effect on unirradiated skin, it had no influence on colony formation in irradiated skin. Smaller colonies, containing 4-8 cells or 9-15 cells, were abundant, particularly after higher doses, which resulted in higher D(0)-values. The majority of these small colonies were abortive and did not progress to larger colonies. There was no statistical evidence for significant variations in the interanimal responses.
研究了照射后表皮克隆原性细胞的存活及集落形成情况，并将其与放射敏感性相关联。开发了一种快速的体内/体外试验，用于定量照射后猪表皮中存活的克隆原性细胞产生的集落。使用标准免疫组织化学方法对全层表皮片中用溴脱氧尿苷（BrdU）标记的细胞进行可视化。在未照射的皮肤中，每平方毫米计数约900个BrdU阳性细胞。在一个时间序列实验中，BrdU标记2 - 24小时后，BrdU阳性细胞数量从平均每平方毫米900个细胞增加到约1400个细胞。在照射后的皮肤中，首次在照射后第14/15天观察到含有≥16个BrdU阳性细胞的集落。每平方厘米这些集落的数量作为皮肤表面剂量的函数产生了一条细胞存活曲线，其D(0)值（±标准误差）为3.9±0.6 Gy。这个相对较高的D(0)值可能是由于铱 - 192源的深度剂量分布迅速下降，因此毛囊上皮对集落形成有很大贡献。在照射后第14/15天，湿性脱屑的体内反应的ED(50)水平为33.6 Gy，对应于每平方厘米2.7个集落。令人惊讶的是，照射后集落数量随时间增加，估计倍增时间约为4天，而D(0)值几乎保持不变。集落数量的增加可能是由于克隆原性细胞的迁移、细胞因子水平升高对休眠克隆原性细胞幸存者的招募，或两者兼而有之。尽管频繁活检导致细胞因子水平升高，对未照射的皮肤有全身影响，但对照射皮肤中的集落形成没有影响。较小的集落，含有4 - 8个细胞或9 - 15个细胞，数量众多，特别是在较高剂量后，这导致了较高的D(0)值。这些小集落中的大多数是发育不全的，没有发展成更大的集落。没有统计学证据表明动物间反应存在显著差异。
