Randomized pilot trial between prostaglandin I2 analog and anti-platelet drugs on peripheral arterial disease in hemodialysis patients.

The effect of the prostaglandin I2 analog, beraprost sodium (BPS), on hemodialysis (HD) patients with peripheral arterial disease (PAD) has not been fully elucidated. The effect of BPS was compared to that of PAD drugs in HD patients with PAD in a multicenter randomized prospective interventional pilot study (J-PADD). Seventy-two PAD patients on HD were entered and randomly divided into two groups; that is, BPS group (Group A: n = 35) and PAD drug (cilostazol or sarpogrelate) group (Group B: n = 37). Primary endpoint was changes in skin perfusion pressure (SPP). Kidney Disease Quality of Life (KDQOL) score, cardiovascular events, PAD events, and adverse events were also evaluated. SPP increased significantly in both groups at 24 weeks from their basal levels. The absolute increase of SPP in Group A and Group B were 15.4 ± 30.0 mm Hg (P < 0.0001) and 20.2 ± 22.1 mm Hg (P = 0.025) (instep), and 13.8 ± 19.3 mm Hg (P < 0.0001) and 9.2 ± 16.3 mm Hg (P = 0.041) (sole), respectively. Changes of KDQOL score showed significantly better result in the role of physical score in Group A compared with Group B. Although heart rate was unchanged in Group A, 9.3/min increase was seen in Group B patients who received cilostazol. There was no intergroup difference in cardiovascular events and/or PAD events between the two groups during the study period. This exploratory pilot study suggested BPS was as effective as anti-platelet drugs in improving microcirculation in HD patients.

Adjusted Anion Gap Is Associated with Glomerular Filtration Rate Decline in Chronic Kidney Disease.

BACKGROUND: Metabolic acidosis is known to accelerate the progression of chronic kidney disease (CKD). However, whether undetermined anions as indicated by the adjusted anion gap (aAG) are associated with estimated glomerular filtration rate (eGFR) decline in patients with CKD is unclear. METHODS: Data from 42 patients with CKD (baseline eGFR, 7.1-52.0 ml/min/ 1.73 m2) without massive proteinuria (urinary protein-creatinine ratio, UPCR <3.5) were retrospectively analyzed. aAG was calculated from serum sodium, serum chloride, serum bicarbonate, serum albumin, serum potassium, serum calcium and serum phosphate. The association between the percentage of the 6-month change of eGFR (%ΔeGFR/6m) and aAG was examined. RESULTS: The mean baseline eGFR was 27.5 ± 11.1 ml/min/1.73 m2 and the mean %ΔeGFR/6m was 13.8 ± 10.3. UPCR and aAG were 1.13 ± 0.93 and 9.48 ± 1.88, respectively. %ΔeGFR/6m was associated with aAG (r = 0.438, p < 0.005), but not with UPCR (r = 0.194, p = 0.218). In multivariate linear regression analyses, aAG remained significantly associated with %ΔeGFR/6m (ß = 0.45, p < 0.01) after controlling for age, baseline eGFR, UPCR and HCO3- concentration. CONCLUSION: These data suggest that aAG appears to be associated with the progression of CKD. aAG might be an independent predictor of CKD progression.

The dimethylthiourea-induced attenuation of cisplatin nephrotoxicity is associated with the augmented induction of heat shock proteins.

Dimethylthiourea (DMTU), a potent hydroxyl radical scavenger, affords protection against cisplatin (CDDP)-induced acute renal failure (ARF). Since the suppression of oxidative stress and the enhancement of heat shock proteins (HSPs) are both reported to protect against CDDP-induced renal damage, we tested whether increased HSP expression is involved in the underlying mechanisms of the DMTU-induced renal protection. We examined the effect of DMTU treatment on the expression of HSPs in the kidney until day 5 following a single injection of CDDP (5 mg/kg BW). DMTU significantly inhibited the CDDP-induced increments of serum creatinine, the number of 8-hydroxyl-2'-deoxyguanosine (8-OHdG)- and terminal deoxynucleotidyl transferase nick-end labeling (TUNEL)-positive tubular cells, and tubular damage score (p<0.05). CDDP significantly increased renal abundances of HO-1, HSP60, HSP72 and HSP90 at days 1, 3, and 5. DMTU significantly augmented only the expression of HSP60 expression mainly in the cytoplasm of the proximal tubular cells at days 1 and 3 in CDDP-induced ARF. DMTU also inhibited the CDDP-induced increment of Bax, a pro-apoptotic protein, in the fraction of organelles/membranes at day 3. The findings suggest that DMTU may afford protection against CDDP-induced ARF, partially through the early induction of cytoplasmic HSP60, thereby preventing the Bax-mediated apoptosis in renal tubular cells.

Inhibition of p21 modifies the response of cortical proximal tubules to cisplatin in rats.

The purpose of this study was to evaluate whether upregulated p21, a cell cycle-inhibitory protein, contributes to cisplatin (CDDP)-induced acute renal failure (ARF) and to acquired resistance to rechallenge injury with CDDP in rats. ARF was induced in rats by injection of CDDP (5 mg/kg) and rechallenge injury to CDDP by the same dose of CDDP 14 days after the first CDDP injection. Rats were treated with p21 antisense oligodeoxynucleotide (ODN) or its vehicle, p21 sense ODN, every 36 h from days 0 to 5 for single CDDP and from days 13 to 19 for rechallenge injury and killed at day 3, 5, 16, or 19. The uptake of FITC-labeled p21 antisense ODNs by cortical proximal tubule (PT) cells was much greater than by PT cells in the outer stripe of outer medulla (OSOM). Administration of antisense induced partial downregulation of p21 mRNA and protein levels in whole kidneys with single CDDP treatment and its rechallenge injury. Antisense significantly aggravated PT necrosis and decreased the number of p21-positive PT cells in the cortex but not in the OSOM in both CDDP-induced ARF and its rechallenge injury. However, antisense did not alter serum creatinine (Scr) and blood urea nitrogen (BUN) levels. Our findings suggested that p21 plays, at least in part, a cytoprotective role in cortical PTs exposed to CDDP, although this does not contribute to renal dysfunction when judged by Scr and BUN levels. Because antisense may not adequately be taken up and/or function in PTs in the OSOM, the role of p21 in PTs in the OSOM in CDDP-induced ARF remains to be clarified.

Kinetics and characterization of initially regenerating proximal tubules in S3 segment in response to various degrees of acute tubular injury.

BACKGROUND: We examined kinetics and characterization of regenerating proximal tubule (PT) cells after various degrees of tubular injury in S3 segments of PT and assessed label-retaining slow cycling cells in S3. METHODS: PT injury was induced by different doses of uranyl acetate (UA) injection into rats, and initially regenerating PTs were identified by in vivo bromodeoxyuridine (BrdU)-labelling before sacrifice or were examined on vimentin positivity. Next, the 3H-thymidine pulse/chase approach was applied to the early regenerating PTs identified by BrdU-labelling after UA injection. RESULTS: Low-dose UA induced focal PT depletion and initial BrdU positivity in the proximal three-quarters of the S3 segment of PT. Autoradiography showed the increased number of label-retaining and label-diluted cells in the proximal three-quarters of S3 in rats treated with low-dose UA compared to normal rats. High-dose UA induced almost complete PT depletion in the proximal three-quarters of S3 and less PT depletion in the distal quarter of S3 and initial BrdU+ cells were restrictedly found in the distal quarter of S3. Label-retaining and label-diluted cells were increasingly found in the entire S3 at day 7, but only label-retaining cells remained in similar numbers in the distal quarter of S3 until day 42. Initially regenerating PT cells with any doses of UA expressed vimentin, suggesting dedifferentiated PT cells. CONCLUSIONS: Initially regenerating cells after PT injury in S3 are dedifferentiated pre-existing PT cells, which may scatter throughout S3 and be responsible for focal repair of S3. Some initially regenerating PT cells in the distal S3 showed persistent label-retaining cells at day 42 after high-dose UA insult and contributed to renewal of the entire S3, thus they might be slow cycling cells with responsibility for S3 repair.

Urinary marker for oxidative stress in kidneys in cisplatin-induced acute renal failure in rats.

BACKGROUND: Establishment of non-invasive urinary biomarkers for the prediction of acute renal failure (ARF) is important. We evaluated whether urinary oxidative stress markers reflect intrarenal oxidative stress in cisplatin (CDDP)-induced ARF, and whether these markers can be used for the prediction of future ARF. METHODS: Urinary malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured up to day 14 post-CDDP (6 mg/kg) injection in rats. MDA and 8-OHdG expressions were examined in kidneys. RESULTS: CDDP induced an increase in serum creatinine (Scr), blood urea nitrogen (BUN), and tubular damage at day 5, increased urinary MDA excretion and MDA expression in kidneys at day 1 (but returned to basal values by day 3), increased urinary excretion of 8-OHdG at day 5 till day 14 (though the number of 8-OHdG-positive tubular cells increased at day 5 and then gradually decreased). Urinary MDA levels at day 1 correlated significantly with Scr (rho = 0.721, P < 0.01) and tubular damage score (rho = 0.840, P < 0.01) at day 5. CONCLUSION: Our findings demonstrated divergent changes of urinary oxidative stress markers in CDDP-induced ARF, and suggested that urinary MDA may be a useful marker for the prediction of the development of CDDP-induced ARF.

High dose chemotherapy and stem cell support in a patient of light- and heavy-chain deposition disease with abnormal marrow cell surface antigens and no monoclonal protein.

A 53-year-old man with nephrotic syndrome and severe renal failure was diagnosed with light- and heavy-chain deposition disease (LHCDD) by renal biopsy. The patient had no monoclonal protein and mild marrow plasmacytosis (6%), but marrow plasma cells expressed CD19(-)CD56+ and predominant monoclonal kappa-chain, indicating plasma cell dyscrasia. Conventional chemotherapy was ineffective and did not improve renal failure. High dose chemotherapy/peripheral blood stem cell transplantation (HDC/PBSCT) was introduced even after hemodialysis to eliminate aberrant clone and normalization of bone marrow cell surface markers. Immunophenotypic analysis of marrow cells facilitates clinical decision making regarding the use of HDC/PBSCT for LHCDD patients without monoclonal protein.

The induction of cell cycle regulatory and DNA repair proteins in cisplatin-induced acute renal failure.

The purpose of this study was to evaluate the expressions and the roles of proteins involved in cell cycle regulation and DNA repair in cis-diamminedichloroplatinum (II) (cisplatin or CDDP)-induced acute renal failure (ARF). Treatment with CDDP (6 mg/kg, iv) induced tubular damage and increased serum creatinine (Scr) and the number of TUNEL-positive cells in the outer stripe of the outer medulla in rats, which reached peak levels at 5 days after CDDP. The expressions of cyclin-dependent kinase inhibitors (p21 and p27), cyclin B1, cyclin D1, PCNA, GADD 45, and GADD 153 were significantly increased in the outer medulla, reaching peak levels at 3 days after CDDP. Increments of p27 and PCNA were observed in the same nuclei. Sodium arsenite (SA), a heavy metal, attenuated tubular damage and increased Scr- and TUNEL-positive cells at 5 days after CDDP. SA augmented CDDP-induced increment of p27 but suppressed the increased expression of cyclin B1 and cyclin D1 at 3 days after CDDP. SA-induced attenuation of nephrotoxicity was associated with enhanced expression of proliferating cell nuclear antigen (PCNA) and growth-arrest and DNA damage (GADD) 153 in damaged tubular cells. Our findings indicated that (1) proteins related to cell cycle regulation and DNA repair are induced in CDDP nephrotoxicity, (2) the SA-induced attenuation of CDDP nephrotoxicity is associated with increased expression of p27 and decreased expression of cyclin B1 and cyclin D1, they all induce cell cycle arrest at G1/S and G2/M, and (3) enhanced expression of DNA repair-related proteins is also associated with attenuation of CDDP-nephrotoxicity.

Rapid improvement of acute pulmonary edema with angiotensin converting enzyme inhibitor under hemodialysis in a patient with renovascular disease.

A 71-year-old man with bilateral renovascular disease was admitted to Hamamatsu University hospital because of appetite loss and acute shortness of breath due to acute pulmonary edema (APE) with accelerated hypertension and renal failure. Hypertension and APE were controlled by an angiotensin converting enzyme inhibitor (ACEI) and four sessions of hemodialysis with reduction of 1.8 kg bodyweight. Renal function was later stabilized and the patient required no ACEI or hemodialysis. A trial of right renal angioplasty 1 month after admission failed and renal function deteriorated (serum creatinine 7.1 mg/dL) with accelerated hypertension, gain of bodyweight and APE. Even after four sessions of hemodialysis with adequate reduction of bodyweight, APE was not controlled, but it rapidly improved after administration of an ACEI, without major bodyweight change. As no apparent cardiac dysfunction was evident, APE might have been caused by a direct action of angiotensin II on hyperpermeability in pulmonary capillaries. Blocking of angiotensin II should be considered in such patients even after introduction of hemodialysis.

Insulin-like growth factor-I increases p21 expression and attenuates cisplatin-induced acute renal injury in rats.

BACKGROUND: Exogenous insulin-like growth factor-I (IGF-I) promotes recovery from ischemic renal injury, but its effect on cisplatin (CDDP)-induced nephrotoxicity and its mechanisms for the attenuation of renal injury are unknown. METHODS: We administered recombinant human IGF-I (rhIGF-I, 150 micro g/day, i.p.) once a day 24 h prior to and after CDDP (5 mg/kg, i.v.) injection in rats. RESULTS: The rhIGF-I treatment significantly decreased serum creatinine (0.92 +/- 0.11 vs 1.50 +/- 0.15 mg/dl; P < 0.05), the tubular damage score, and the ratio of apoptotic cells to tubular epithelial cells in the outer stripe of the outer medulla on day 5 ( P < 0.05). rhIGF-I significantly increased the numbers of p21-positive nuclei (5.15 +/- 0.19 vs 3.45 +/- 0.42/x400 high-power field (HPF); P < 0.05) and proliferating cell nuclear antigen (PCNA)-positive nuclei (28.61 +/- 1.89 vs 18.26 +/- 2.14/x400 HPF; P < 0.05), but decreased the number of cyclin D1-positive cells (3.3 +/- 0.3 vs 6.3 +/- 1.7/x400 HPF; P < 0.05) on day 3. rhIGF-I did not alter 5-bromo-3-deoxyuridine (BrdU) incorporation. CONCLUSIONS: Our findings suggested that rhIGF-I increased renal p21 and PCNA expression, but reduced cyclin D1 expression in CDDP-treated kidneys. Exogenous rhIGF-I may ameliorate renal damage, in part by stopping the cell cycle at G1/S phase. Exogenous insulin-like growth factor-I (IGF-I) promotes recovery from ischemic renal injury, but its effect on cisplatin (CDDP)-induced nephrotoxicity and its mechanisms for the attenuation of renal injury are unknown.

A simplified method for HPLC determination of creatinine in mouse serum.

Mouse models are frequently used to study renal function. However, mouse serum contains chromagens that interfere with standard picric acid-based assays for serum creatinine. Several alternative methods exist for serum creatinine measurements, including assay by high-performance liquid chromatography (HPLC), but only one has been adapted to mouse serum. Creatinine was measured in serum by acetonitrile deproteinization, followed by isocratic, cation exchange HPLC. The HPLC method was compared with a standard alkaline picrate colorimetric assay, using serum from animals with low-to-moderate renal injury. Acidification of acetonitrile with HCl in the deproteinization step produced variable results, including an extra peak that interfered with integration of the creatinine peak or loss of the creatinine peak. Deproteinizing with acetonitrile alone resulted in a more reliable measurement of serum creatinine, which was validated by a series of known additions of creatinine standard. The HPLC assay was reproducible with coefficients of variation from 1.6 to 5.1%. The picric acid assay overestimated serum creatinine, when directly compared with the HPLC assay. The extent of overestimation, up to sixfold, was greatest at normal (0.1 to 0.2 mg/dl) to moderately elevated (0.5 mg/dl) serum creatinine levels. Mouse serum contains substances that interfere with standard picric acid assays for creatinine. Our new HPLC assay can accurately detect creatinine from 5 microl of mouse serum. These results support the widespread adoption of HPLC to accurately measure serum creatinine in mouse models of renal injury.

Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice.

BACKGROUND: Sepsis is a common cause of acute renal failure (ARF). The incidence of sepsis increases dramatically after 50 years of age; however, most ARF studies are performed in young mice. METHODS: We performed two common sepsis models, lipopolysaccharide (LPS) administration and cecal ligation puncture (CLP) in aged mice. We developed a fully treated CLP model in aged mice by treating mice with fluid resuscitation and antibiotics. RESULTS: LPS induced renal injury in aged but not young mice. However, volume resuscitation starting within 6 hours decreased renal injury. We then used this fluid resuscitation scheme, along with antibiotics, to develop a fully treated CLP model in aged mice. Mice subjected to CLP developed functional and histologic ARF and multiple organ damage. Treatment with ethyl pyruvate, even when started 12 hours after surgery, decreased serum creatinine, tubular damage, and multiple organ injury at 24 hours. Ethyl pyruvate decreased plasma tumor necrosis factor-alpha (TNF-alpha), and kidney mRNA for TNF alpha, tissue factor, and plasminogen activator inhibitor-1 (PAI-1), and increased mRNA for urokinase-like plasminogen activator. CONCLUSION: CLP in aged mice causes functional and histologic changes consistent with human ARF. A single dose of ethyl pyruvate inhibits renal and multiple organ damage, and is still effective when given 12 hours after surgery.

Detection of inflammation following renal ischemia by magnetic resonance imaging.

BACKGROUND: Determining the disease culprits in human acute renal failure (ARF) has been difficult because of the paucity of renal biopsies and the lack of noninvasive methods to determine the location or cause of renal injury. Recently, ultrasmall superparamagnetic iron oxide (USPIO) particles have been used to detect inflammation in animal models. Therefore, we tested if USPIO enhanced magnetic resonance imaging (MRI) could detect inflammation in ischemic ARF in rats. METHODS: Rats were subjected to 40 or 60 minutes of bilateral ischemia or injected with mercuric chloride. MR images were obtained before and 24 hours after USPIO injection, and the signal intensity decrease in the outer medulla was measured. Cells containing iron particles were identified by iron staining and transmission electron microscopy (TEM). Leukocytes were identified by ED-1 and chloracetate esterase staining. RESULTS: Injection of USPIO particles caused a black band to appear in the outer medulla at 48, 72, and 120 hours after ischemia. This band was not detected in normal animals, 24 hours after ischemia, or 48 hours after mercuric chloride injection. The signal intensity change in the outer medulla correlated with serum creatinine and the number of iron particle containing cells. Most infiltrating cells were macrophages, and iron particles were present inside lysosomes of macrophages. USPIO injection did not alter renal function in normal or ischemic animals. CONCLUSION: USPIO-enhanced MRI could detect inflammation noninvasively from 48 hours after 40 or 60 minutes of renal ischemia in rats. This method might be useful to understand the pathogenesis of human ARF and to evaluate the effectiveness of anti-inflammatory agents.

Frozen protein arrays: a new method for arraying and detecting recombinant and native tissue proteins.

DNA microarrays are powerful tools for high throughput analysis of gene expression; however, they do not measure protein expression. Current methods for producing protein arrays require sophisticated equipment or extensive protein modification. We developed a low overhead, customizable assay platform called frozen protein arrays that can detect native proteins in protein lysates. Frozen protein arrays were formed from a block of frozen histologic embedding compound containing an array of wells. The wells were filled with samples, which freeze and bond to the block. Cryosections were cut and transferred to nitrocellulose-coated slides. The reproducibility, linearity, and sensitivity was confirmed using frozen protein arrays filled with prostate specific antigen. Frozen protein arrays could detect native tissue proteins. The alpha1 subunit of NaK-ATPase was detected in rat kidneys with a coefficient of variation of 4.3-6.6%. Frozen protein array analysis indicated that the protein abundance decreased by 48.7% following renal ischemia, similar to the 40% decrease by Western blotting. We conclude that frozen protein arrays are a low cost, moderate size platform for arraying samples including protein lysates. Production of many identical frozen protein arrays is easy, inexpensive, and requires only small sample volumes. The method is gentle on proteins as they remain frozen during production.

alpha-Melanocyte-simulating hormone and interleukin-10 do not protect the kidney against mercuric chloride-induced injury.

The anti-inflammatory cytokines alpha-melanocyte-stimulating hormone (MSH) and interleukin (IL)-10 inhibit acute renal failure (ARF) after ischemia or cisplatin administration; however, these agents have not been tested in a pure nephrotoxic model of ARF. Therefore, we examined the effects of alpha-MSH and IL-10 in HgCl(2)-induced ARF. Mice were injected subcutaneously with HgCl(2) and then given vehicle, alpha-MSH, or IL-10 by intravenous injection. Animals were killed to study serum creatinine, histology, and myeloperoxidase activity. Treatment with either alpha-MSH or IL-10 did not alter the increase in serum creatinine, tubular damage, or leukocyte accumulation at 48 h after HgCl(2) injection. Because alpha-MSH and IL-10 are active in other injury models that involve leukocytes, we studied the time course of tubular damage and leukocyte accumulation to investigate whether leukocytes caused the tubular damage or accumulated in response to the tubular damage. Tubular damage was present in the outer stripe 12 h after HgCl(2) injection. In contrast, the number of leukocytes and renal myleoperoxidase activity were normal at 12 h but were significantly increased at 24 and 48 h after injection. We conclude that neither alpha-MSH nor IL-10 altered the course of HgCl(2)-induced renal injury. Because the tubular damage preceded leukocyte infiltration, the delayed leukocyte accumulation may play a role in the removal of necrotic tissue and/or tissue repair in HgCl(2)-induced ARF.

Role of the increase in p21 in cisplatin-induced acute renal failure in rats.

The goal of this study was to clarify the role of p21, a cyclin-dependent kinase inhibitor, in acute renal failure (ARF). This was accomplished with the examination of the renal expression of p21 in cisplatin (CDDP)-induced ARF and in rechallenge injury with CDDP. The injection of CDDP (5 mg/kg) into rats induced increases in serum creatinine and tubular damage and the number of in situ DNA nick end labeling-positive cells, which peaked at day 5, followed by recovery to control levels by day 14. The rechallenge with the same dose of CDDP 14 d after the first dose of CDDP induced significantly less injury and no significant increase in in situ DNA nick end labeling-positive cells. The first CDDP dose significantly increased p53-positive nuclei at day 1, which disappeared by day 5, and the number of p21-positive nuclei, which had two peaks on days 3 and 9. The number of proliferating cell nuclear antigen (PCNA)-positive nuclei peaked at days 3 and 12. A significant increase in the incorporation of 5-bromo 2'-deoxyuridine (BrdU) was found at day 5 and peaked at day 7. The second injection of CDDP induced significant increases in the number of p21-, p53-, and PCNA-positive nuclei within 2 d but did not affect the incorporation of BRDU: These findings suggested that (1) CDDP induced two peaks of the increase in p21; (2) the first peak occurred shortly after CDDP and was accompanied by overexpression of p53 and PCNA but not with BrdU incorporation, possibly reflecting G1 arrest and DNA repair; (3) the second peak of p21 occurred through an p53-independent pathway and may contribute to cell differentiation; and (4) the overexpression of p21 and PCNA in rechallenge injury may contribute to acquired resistance in CDDP-induced ARF via enhanced DNA repair.

Elevated erythropoietin receptor and transforming growth factor-beta1 expression in stenotic arteriovenous fistulae used for hemodialysis.

The issue of whether recombinant human erythropoietin (rhEPO) increases thrombosis of arteriovenous (AV) fistulae used for hemodialysis remains unclear. Thrombosis often occurs at stenotic segments of fistulae where there is marked intimal hyperplasia and extracellular matrix accumulation. Increased expression of transforming growth factor-beta1 (TGF-beta1) has been shown to be involved in the development of atherosclerotic lesions by promoting intimal hyperplasia and extracellular matrix accumulation. To clarify the role of rhEPO in the development of stenosis of AV fistulae, this study examined expression of the erythropoietin receptor (EPO-R), TGF-beta1, plasminogen activator inhibitor type 1 (PAI-1), cellular fibronectin containing an extra domain A (EDA+), and TGF-beta1 mRNA, and assessed in situ rhEPO binding in tissue specimens from seven cutaneous veins and eight patent and seven stenosed portions of AV fistulae of patients undergoing dialysis. Prominent intimal hyperplasia was evident in the stenosed segments. Significant elevation in expression of EPO-R and TGF-beta1 was noted in patent AV fistulae compared to the cutaneous veins. Significant enhancement of EPO-R and TGF-beta expression was detected in the stenotic fistulae. Fibronectin EDA+ and PAI-1 expression was increased in intimal hyperplasia compared to patent fistulae and cutaneous veins. Elevated EPO-R expression was further confirmed by in situ binding of biotin-labeled rhEPO in stenosed tissue specimens. It is hypothesized that increased rhEPO binding due to elevated EPO-R expression contributes to the development of AV fistula stenosis caused by intimal hyperplasia and extracellular matrix accumulation in response to increased TGF-beta1 expression in patients receiving hemodialysis.