| Backgroud and objective: The diagnostic rate of acute kidney injury increases everyyear and the incidence increases with age.Renal tubular epithelia cells(TECs) injured isa physiopathological mechanism. The role of stem cells in the maintenance and repairrenal TECs damage became the focus of attention in recent years, but its mechanism isunclear. In this study, first, we investigated the incidence, risk factors and outcome ofAKI in the elderly. Second, we isolated, cultured and identified the kidney stem cellsfrom rat kidney in vitro. Third, we investigated the repair roles of the kidney stem cellsin the regeneration of injured tubular epithelial cell. The aim is to provide a evidence forthe role of stem cell in the elderly with AKI.Methods: The clinical data of the patients older than65admitted in the Chinese PLAGeneral Hospital from June1,2008to December31,2009were collected. Multivariatelogistic regression was performed to analyze the possible risk factors for the endpoint in90days post-AKI. Cox proportional hazard models were used to estimate HR fordeveloping death in one year. Kidney stem cells(KSC) were isolated from rat renalpapilla. The cells growth pattern was detected by MTT assay. The different differentialmedium was used to detect its multi-directional differentiation ability. Cell-surfacemarkers were analyzed by flow cytometry. Human renal tubular epithelia cells(HKC)were treated with0.1%μmol/L antimycin A for30minutes and with non-glucosemedium for one hour to induce anoxyaemia and reperfusion evironment. Then, the HKCwere treated with the supernatant of KSC, and co-cultrure with KSC using transwell.Cellular ATP and the supernatant of MDA, SOD and LDH were detected at1h,4h,24hafter reperfusion. Stem cells wre detected with electron microscopy and apoptosis ratesof HKC were measured by flow cytometry.Results: The overall incidence of AKI in the hospitalized elderly patients was10.8%.The incidence of AKI increased with the growth of age. A single and multifactorialanalysis of etiologies all showed that infections were the major causes of AKI in those patients. Multivariate analysis of logistic and Cox proportional hazard models showedthe following variables as of independent risk factors: multiple organ dysfunctionsyndrome, gastrointestinal bleeding, mechanical ventilation and malnutrition. In vitrostudy, the cells from the renal papilla could be induced to differentiate into adipocytesand osteblasts. The flow cytometer analysis showed that these cells wereCD29,CD44,CD90positive, and CD45negative. Hypoxia and reoxygenation cell modelwas induced by0.1μmol/L antimycin A. In the study of intervention with the stem cellsupernatant, ATP content of cells and total SOD value of supernatant were graduallyincreased over time, MDA and LDH values decreased gradually over time, thisphenomenon in the group of stem cell supernatant is more pronounced. The study ofco-culture showed that KSC was less capable to migrate through the micropores oftranswell to the lower compartment than BMSCs.Conlusion: The incidence of AKI in the very elderly hospitalized patients was high.Infections, hypovolemia, nephrotoxic drugs and cardiovascular diseases were among thecommon causes. Renal papilla was a niche of kidney stem cells, these cells had thebiological characteristics of stem cells. These kidney stem cells may protect andparticipate in the repair of ischemic reperfusion injury of HKC through the excretion ofcytokine. |
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