Urine exosomal ceruloplasmin: a potential early biomarker of underlying kidney disease.

Background: Previously we found that kidney tissue and urinary exosomes from patients of diabetic kidney disease showed high levels of ceruloplasmin (CP). Because CP is an acute-phase protein of kidney origin, it could be an early marker of many other kidney diseases. To investigate this hypothesis, we first measured urine exosomal and kidney expression of CP in non-diabetic chronic kidney disease (CKD) patients (membranous nephropathy, focal segmental glomerulosclerosis, lupus nephritis and IgA nephropathy) followed by a longitudinal study in rat passive Heymann nephritis (PHN), a model of human membranous nephropathy.

Peptiduria: a potential early predictor of diabetic kidney disease.

Background: To protect the kidney effectively with medication in type 2 diabetics, it is crucial to identify such at-risk patients early for treatment. We investigated whether peptiduria precedes proteinuria (the earliest urinary marker in our model), and thereby serve as an early predictor of diabetic nephropathy.

Methods: A longitudinal study was performed in a rat model of diabetic nephropathy.

Progressive glomerular and tubular damage in sickle cell trait and sickle cell anemia mouse models.

Homozygosity for the hemoglobin (Hb) S mutation (HbSS, sickle cell anemia) results in hemoglobin polymerization under hypoxic conditions leading to vaso-occlusion and hemolysis. Sickle cell anemia affects 1:500 African Americans and is a strong risk factor for kidney disease, although the mechanisms are not well understood. Heterozygous inheritance (HbAS; sickle cell trait) affects 1:10 African Americans and is associated with an increased risk for kidney disease in some reports.

Bitter Melon Extract Promotes Granulation Tissue Growth and Angiogenesis in the Diabetic Wound.

Objective: Bitter melon is a plant fruit that has been shown to exert a hypoglycemic effect when used systemically in patients with diabetes. This study was designed to investigate the topical effect of bitter melon on diabetic wounds using the wound chamber model in rats.

Design: Two bilateral wound chambers were implanted subcutaneously in the thoracic-lumbar region of male Sprague-Dawley rats.

In Diabetic Kidney Disease Urinary Exosomes Better Represent Kidney Specific Protein Alterations Than Whole Urine.

Background: Predicting or diagnosing underlying kidney disease by analyzing whole urine remains the mainstay of nephrology practice. However, whole urine is a poor compartment to assess many structural changes in the kidney because whole urine contains only a few proteins derived from the kidney itself. Urinary exosomes, on the other hand, which are derived from the kidney, contain proteins secreted by the kidney.

Autologous tissue patch rich in stem cells created in the subcutaneous tissue.

Aim: To investigate whether we could create natural autologous tissue patches in the subcutaneous space for organ repair.

Methods: We implanted the following three types of inert foreign bodies in the subcutaneous tissue of rats to produce autologous tissue patches of different geometries: (1) a large-sized polyvinyl tube (L = 25 mm, internal diameter = 7 mm) sealed at both ends by heat application for obtaining a large flat piece of tissue patch for organ repair; (2) a fine polyvinyl tubing (L = 25 mm, internal diameter = 3 mm) for creating cylindrically shaped grafts for vascular or nerve repair; and (3) a slurry of polydextran particle gel for inducing a bladder-like tissue. Implantation of inert materials was carried out by making a small incision on one or either side of the thoracic-lumbar region of rats.

Genetic variants and cell-free hemoglobin processing in sickle cell nephropathy.

Intravascular hemolysis and hemoglobinuria are associated with sickle cell nephropathy. ApoL1 is involved in cell-free hemoglobin scavenging through association with haptoglobin-related protein. APOL1 G1/G2 variants are the strongest genetic predictors of kidney disease in the general African-American population.

Activated omentum slows progression of CKD.

Stem cells show promise in the treatment of AKI but do not survive long term after injection. However, organ repair has been achieved by extending and attaching the omentum, a fatty tissue lying above the stomach containing stem cells, to various organs. To examine whether fusing the omentum to a subtotally nephrectomized kidney could slow the progression of CKD, we used two groups of rats: an experimental group undergoing 5/6 nephrectomy only and a control group undergoing 5/6 nephrectomy and complete omentectomy.

Stem cells from foreign body granulation tissue accelerate recovery from acute kidney injury.

Background: In previous studies, we obtained mesenchymal stem cells called granulation tissue stem cells (GTSC) from a regenerating granulation tissue created by placing a foreign body in the subcutaneous tissue of rats. Here, we used GTSC to ameliorate ischemia/reperfusion-induced acute kidney injury (AKI) in rats.

Methods: In two groups of Fischer rats, we induced ischemia/reperfusion injury.

Culture of omentum-induced regenerating liver yielded hepatocyte-committed stem cells.

Earlier we showed that when omentum, activated by inert particles, is allowed to fuse to a wedge cut in the liver, it induces stem cell proliferation in the liver resulting in massive liver regeneration. Here, we attempt to culture stem cells from the omentum-induced regenerating liver tissue. Cells from regenerating liver tissue were harvested and cultured.

Foreign body-induced granulation tissue is a source of adult stem cells.

In the current study, we have cultured and propagated the cells obtained from the granulation tissue that forms around perforated polyvinyl tubes placed in the subcutaneous space of normal rats. We found that these cells (called granulation tissue-derived stem cells [GTSCs]) expressed markers of embryonic pluripotent cells (Oct-4 and Nanog) and of adult stem cells (CXCR4 and Thy1.1) as well as produced high levels of vascular endothelial growth factor (VEGF) for up to 10 passages.

Omentum facilitates liver regeneration.

Aim: To investigate the mechanism of liver regeneration induced by fusing the omentum to a small traumatic injury created in the liver. We studied three groups of rats. In one group the rats were omentectomized; in another group the omentum was left in situ and was not activated, and in the third group the omentum was activated by polydextran particles.

Stromal cells cultured from omentum express pluripotent markers, produce high amounts of VEGF, and engraft to injured sites.

When rat omentum becomes activated by intraperitoneal injection of inert polydextran particles, these particles are rapidly surrounded by cells that express markers of adult stem cells (SDF-1alpha, CXCR4, WT-1) and of embryonic pluripotent cells (Oct-4, Nanog, SSEA-1). We have cultured such cells, because they may offer a convenient source of adult stem cells, and have found that they retain stem cell markers and produce high levels of vascular endothelial growth factor for up to ten passages. After systemic or local injection of these cultured cells into rats with acute injury of various organs, the cells specifically engraft at the injured sites.

Activated omentum becomes rich in factors that promote healing and tissue regeneration.

In order to study the mechanism by which an omental pedicle promotes healing when applied to an injured site, we injected a foreign body into the abdominal cavity to activate the omentum. One week after the injection, we isolated the omentum and measured blood vessel density, blood content, growth and angiogenesis factors (VEGF and others), chemotactic factors (SDF-1 alpha), and progenitor cells (CXCR-4, WT-1). We found that the native omentum, which consisted mostly of adipose tissue, expanded the mass of its non-adipose part (milky spots) 15- to 20-fold.

Impaired integration of endothelial progenitor cells in capillaries of diabetic wounds is reversible with vascular endothelial growth factor infusion.

To understand impaired angiogenesis in diabetic wounds, polyvinyl tubes were implanted subcutaneously in rats to form a granulation tissue for 2 weeks and the granulation tissue was studied after inducing diabetes with streptozotocin. By 1 week of diabetes, the granulation tissue was bloody and thinner than controls, its medial layer was depleted of microvessels, and the surviving vessels appeared dehisced. Vascular endothelial growth factor (VEGF) in the diabetic granulation tissue was reduced by 50% compared with control granulation tissue.

Transplanting fragments of diabetic pancreas into activated omentum gives rise to new insulin producing cells.

To determine if pancreatic progenitor cells can be induced to form insulin producing cells in vivo, we auto-transplanted fragments of streptozotocin-induced diabetic pancreas into omentum pre-injected with a foreign material. As shown previously, omentum pre-activated in this manner becomes rich in growth factors and progenitor cells. After auto-transplanting diabetic pancreas in the activated omentum, new insulin secreting cells appeared in the omentum in niches surrounding the foreign particles--a site previously shown to harbor progenitor cells.

Glomerular epithelial cells transform to myofibroblasts: early but not late removal of TGF-beta1 reverses transformation.

Studies were carried out to determine whether epithelial-mesenchymal transformation (EMT), well described in renal tubular epithelial cells, also occurs in glomerular epithelial cells and whether it is reversible. To this effect, cultured glomerular epithelial cells were incubated with TGF-beta(1) and their transformation into myofibroblasts was studied. At 4 days, the cells altered their phenotype, as shown by a change in shape, an increase in intracellular staining for alpha-smooth muscle actin (alpha-SMA), a decrease in membrane staining for cytokeratin, and an increase in matrix deposition.

Antagonism of vascular endothelial growth factor results in microvessel attrition and disorganization of wound tissue.

Vascular endothelial growth factor (VEGF) is a potent growth factor that is indispensable for the development of blood vessels in the fetus and for wound healing in adults. VEGF likely plays a role in maintaining the blood vessels once they have been formed. It is not clear, however, whether a low tissue VEGF (caused either by disease or by systemic administration of VEGF antagonists) can cause abnormalities in preexisting blood vessels, especially of wound tissue that requires high local levels of VEGF for healing.

Decreased urinary peptide excretion in patients with renal disease.

Background: Normal urine contains low-molecular-weight peptides or protein fragments that have been poorly studied, primarily because of the technical difficulty of measuring peptides in the presence of proteins. We studied these substances in healthy subjects and patients with renal disease and varying degrees of proteinuria to understand the factors that determine their excretion.

Methods: We estimated these substances as the difference between results using the Lowry method (which detects both proteins and peptides) and those obtained using the dye-binding Bradford (Biorad) method (Biorad Laboratories Inc, Hercules, CA; which detects only proteins).

Degradation of albumin by the renal proximal tubule cells and the subsequent fate of its fragments.

Background: In view of recent reports of large amounts of albumin fragments present in normal urine we investigated the mechanism of albumin handling by the proximal tubule.

Methods: We injected (125)I-albumin intravenously in rats and measured the excretion of intact and degraded (125)I-albumin in the urine by trichloroacetic acid (TCA) precipitation. The excretion rate of intact (125)I-albumin was compared to that obtained by routine radioimmunoassay (RIA).

Vascular factors altered in glucose-treated mesangial cells and diabetic glomeruli. Changes in vascular factors impair endothelial cell growth and matrix.

We studied the effect of a high glucose (HG) environment on the vascular factors that are secreted by mesangial cells, and regulate endothelial growth and mesangial matrix deposition. To this effect, we measured the vascular factors in the glomeruli of streptozotocin-induced diabetic kidneys and in mesangial cells exposed to a HG concentration. We then transferred the media of mesangial cells previously exposed to high glucose to cultured endothelial cells to study the effects on endothelial growth, matrix formation, and in vitro capillary proliferation.

Handling of low-density lipoprotein by the renal tubule: release of fragments due to incomplete degradation.

Because the mechanism by which lipoproteins are processed and modified in the renal tubule in patients with nephrosis is not completely understood, we studied the handling of low-density lipoprotein (LDL) in perfused rat kidneys made permeable by protamine. Protamine pretreatment increased the clearance of 125(I) LDL 25-fold compared to controls, thereby simulating a proteinuric kidney. Similar studies were also conducted in kidneys of rats made proteinuric by the induction of passive Heymann nephritis.