Racusen L C, Fivush B A, Li Y L, Slatnik I, Solez K
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Lab Invest. 1991 Apr;64(4):546-56.
"Acute tubular necrosis" in humans is often characterized histologically by tubular cell loss and nonreplacement rather than by frank cellular necrosis. It has been assumed that tubular cells detach from the tubular basement membrane after the occurrence of irreversible cell injury and/or cell death. We examined voided urine from patients with native kidney and transplant kidney "acute tubular necrosis" and found significant tubular cell shedding with up to 100% viability of voided tubular cells, as determined by exclusion of trypan blue. Histochemical stains for the brush border enzyme gamma-glutamyl transpeptidase and electron microscopy of cell isolates demonstrated that 30 to 100% of the voided cells were of proximal tubule origin. Moreover, epithelial cell cultures were readily established from noncontaminated voided specimens, and more than 80% of the cells in monolayers expressed gamma-glutamyl transpeptidase activity in vitro. Electron microscopy of cell monolayers confirmed proximal tubular differentiation in the majority of cells in the monolayer, with the remainder having an appearance more consistent with distal origin. In rabbit models of acute ischemic (pedicle clamp) and toxic (HgCl2 and glycerol-induced) injury, tubular cell shedding was also significant, with a mean of 25 to 30% of the voided cells viable. Epithelial cells were successfully cultured and passed from animals with ischemic renal injury. In vitro studies were carried out in cultured human proximal tubular cells to assess suitability of this system for more direct study of the phenomenon of cell detachment in response to injury. We found significant changes in cell shape in response to exposure to anoxia and HgCl2 in these cultures, with extensive cell rounding and retraction at times when cell viability remained high. This in vitro system could prove useful for defining mechanisms of renal tubular cell detachment in response to injury and for examining potential interventions to prevent epithelial disruption and loss of functional integrity. These strategies may ultimately have clinical relevance in patients with "acute tubular necrosis".
人类的“急性肾小管坏死”在组织学上通常表现为肾小管细胞丢失且无细胞替代，而非明显的细胞坏死。一直以来人们认为，在发生不可逆性细胞损伤和/或细胞死亡后，肾小管细胞会从肾小管基底膜脱落。我们检测了患有天然肾和移植肾“急性肾小管坏死”患者的晨尿，发现有大量肾小管细胞脱落，通过台盼蓝排斥试验测定，排出的肾小管细胞活力高达100%。对刷状缘酶γ-谷氨酰转肽酶进行组织化学染色以及对分离出的细胞进行电子显微镜检查表明，排出的细胞中有30%至100%源自近端小管。此外，从无污染的排出标本中很容易建立上皮细胞培养物，单层培养物中超过80%的细胞在体外表达γ-谷氨酰转肽酶活性。对细胞单层进行电子显微镜检查证实，单层中的大多数细胞呈现近端小管分化特征，其余细胞的外观更符合远端小管来源。在急性缺血（肾蒂钳夹）和中毒（氯化汞和甘油诱导）损伤的兔模型中，肾小管细胞脱落也很显著，排出细胞的平均活力为25%至30%。成功培养了患有缺血性肾损伤动物的上皮细胞并进行传代。在培养的人近端肾小管细胞中进行了体外研究，以评估该系统是否适合更直接地研究细胞对损伤的脱离现象。我们发现，在这些培养物中，细胞暴露于缺氧和氯化汞后，细胞形态发生了显著变化，在细胞活力仍然很高的时候，细胞会大量变圆并回缩。这个体外系统可能有助于确定肾小管细胞对损伤的脱离机制，并研究预防上皮破坏和功能完整性丧失的潜在干预措施。这些策略最终可能对患有“急性肾小管坏死”的患者具有临床意义。
