Department of Oncology, University of Oxford, Oxford, UK.
Gut. 2012 Oct;61(10):1380-9. doi: 10.1136/gutjnl-2011-301174. Epub 2011 Dec 26.
Little is known about the stem cell organisation of the normal oesophagus or Barrett's metaplastic oesophagus. Using non-pathogenic mitochondrial DNA mutations as clonal markers, the authors reveal the stem cell organisation of the human squamous oesophagus and of Barrett's metaplasia and determine the mechanism of clonal expansion of mutations.
Mutated cells were identified using enzyme histochemistry to detect activity of cytochrome c oxidase (CCO). CCO-deficient cells were laser-captured and mutations confirmed by PCR sequencing. Cell lineages were identified using immunohistochemistry.
The normal squamous oesophagus contained CCO-deficient patches varying in size from around 30 μm up to about 1 mm. These patches were clonal as each area within a CCO-deficient patch contained an identical mitochondrial DNA mutation. In Barrett's metaplasia partially CCO-deficient glands indicate that glands are maintained by multiple stem cells. Wholly mutated Barrett's metaplasia glands containing all the expected differentiated cell lineages were seen, demonstrating multilineage differentiation from a clonal population of Barrett's metaplasia stem cells. Patches of clonally mutated Barrett's metaplasia glands were observed, indicating glands can divide to form patches. In one patient, both the regenerating squamous epithelium and the underlying glandular tissue shared a clonal mutation, indicating that they are derived from a common progenitor cell.
In normal oesophageal squamous epithelium, a single stem cell clone can populate large areas of epithelium. Barrett's metaplasia glands are clonal units, contain multiple multipotential stem cells and most likely divide by fission. Furthermore, a single cell of origin can give rise to both squamous and glandular epithelium suggesting oesophageal plasticity.
人们对正常食管或 Barrett 化生食管的干细胞组织知之甚少。作者使用非致病性线粒体 DNA 突变作为克隆标记，揭示了人鳞状食管和 Barrett 化生的干细胞组织，并确定了突变克隆扩展的机制。
通过酶组织化学检测细胞色素 c 氧化酶（CCO）活性来鉴定突变细胞。用激光捕获 CCO 缺陷细胞，并通过 PCR 测序确认突变。用免疫组织化学鉴定细胞谱系。
正常鳞状食管中存在大小从约 30μm 到约 1mm 不等的 CCO 缺陷斑块。这些斑块是克隆的，因为 CCO 缺陷斑块内的每个区域都包含相同的线粒体 DNA 突变。在 Barrett 化生中，部分 CCO 缺陷的腺体表明腺体由多个干细胞维持。完全突变的 Barrett 化生腺体含有所有预期的分化细胞谱系，证明从克隆的 Barrett 化生干细胞群体中具有多谱系分化能力。观察到克隆性突变的 Barrett 化生腺体的斑块，表明腺体可以分裂形成斑块。在一名患者中，再生的鳞状上皮和其下方的腺组织共享一个克隆突变，表明它们来自共同的祖细胞。
在正常食管鳞状上皮中，单个干细胞克隆可以覆盖大片上皮。Barrett 化生的腺体是克隆单位，包含多个多能干细胞，最有可能通过裂殖分裂。此外，单个起始细胞可以产生鳞状和腺状上皮，提示食管可塑性。
