Fischer S, Cassivi S D, Xavier A M, Cardella J A, Cutz E, Edwards V, Liu M, Keshavjee S
Division of Thoracic Surgery, Toronto General Hospital, Ontario, Canada.
Ann Surg. 2000 Mar;231(3):424-31. doi: 10.1097/00000658-200003000-00016.
To examine the presence and extent of apoptosis as well as the affected cell types in human lung tissue before, during, and after transplantation.
Apoptosis has been described in various human and animal models of ischemia-reperfusion injury, including heart, liver, and kidney, but not in lungs. Therefore, the presence of apoptosis and its role in human lungs after transplantation is not clear.
Lung tissue biopsies were obtained from 20 consecutive human lungs for transplantation after cold ischemic preservation (1-5 hours), after warm ischemia time (during implantation), and 30, 60, and 120 minutes after graft reperfusion. To detect and quantify apoptosis, fluorescent in situ end labeling of DNA fragments (TUNEL assay) was used. Electron microscopy was performed to verify the morphologic changes consistent with apoptosis and to identify the cell types, which were lost by apoptosis.
Almost no evidence of apoptosis was found in specimens after immediate cold and warm ischemic periods. Significant increases in the numbers of cells undergoing apoptosis were observed after graft reperfusion in a time-dependent manner. The mean fraction of apoptotic cells at 30, 60, and 120 minutes after graft reperfusion were 16.6%, 22.1%, and 34.9% of total cells, respectively. Most of the apoptotic cells appeared to be alveolar type II pneumocytes, as confirmed by electron microscopy.
Programmed cell death (apoptosis) appears to be a significant type of cell loss in human lungs after transplantation, and this may contribute to ischemia-reperfusion injury during the early phase of graft reperfusion. This cell loss might be responsible for severe organ dysfunction, which is seen in 20% of patients after lung transplantation. Therefore, this work is of importance to surgeons for the future development of interventions to prevent cell death in transplantation.
研究人类肺组织在移植前、移植过程中及移植后凋亡的存在情况、程度以及受影响的细胞类型。
凋亡已在各种人类和动物的缺血再灌注损伤模型中被描述，包括心脏、肝脏和肾脏，但在肺中尚未见报道。因此，移植后人肺中凋亡的存在及其作用尚不清楚。
从20例连续的用于移植的人类肺组织中获取活检标本，分别在冷缺血保存（1 - 5小时）后、热缺血期（植入过程中）以及移植肺再灌注后30、60和120分钟时获取。为检测和定量凋亡，采用DNA片段荧光原位末端标记法（TUNEL检测）。进行电子显微镜检查以验证与凋亡一致的形态学变化并识别因凋亡而丢失的细胞类型。
在即刻冷缺血和热缺血期后的标本中几乎未发现凋亡迹象。移植肺再灌注后，凋亡细胞数量呈时间依赖性显著增加。移植肺再灌注后30、60和120分钟时凋亡细胞的平均比例分别为总细胞数的16.6%、22.1%和34.9%。电子显微镜检查证实，大多数凋亡细胞似乎是Ⅱ型肺泡上皮细胞。
程序性细胞死亡（凋亡）似乎是人类肺移植后细胞丢失的一种重要类型，这可能导致移植肺再灌注早期的缺血再灌注损伤。这种细胞丢失可能是导致20%的肺移植患者出现严重器官功能障碍的原因。因此，这项工作对外科医生未来开发预防移植中细胞死亡的干预措施具有重要意义。
