Sodium-Glucose Linked Cotransporter-2 Inhibition Does Not Attenuate Disease Progression in the Rat Remnant Kidney Model of Chronic Kidney Disease.

Pharmacological inhibition of the proximal tubular sodium-glucose linked cotransporter-2 (SGLT2) leads to glycosuria in both diabetic and non-diabetic settings. As a consequence of their ability to modulate tubuloglomerular feedback, SGLT2 inhibitors, like agents that block the renin-angiotensin system, reduce intraglomerular pressure and single nephron GFR, potentially affording renoprotection. To examine this further we administered the SGLT2 inhibitor, dapagliflozin, to 5/6 (subtotally) nephrectomised rats, a model of progressive chronic kidney disease (CKD) that like CKD in humans is characterised by single nephron hyperfiltration and intraglomerular hypertension and where angiotensin converting enzyme inhibitors and angiotensin receptor blockers are demonstrably beneficial. When compared with untreated rats, both sham surgery and 5/6 nephrectomised rats that had received dapagliflozin experienced substantial glycosuria. Nephrectomised rats developed hypertension, heavy proteinuria and declining GFR that was unaffected by the administration of dapagliflozin. Similarly, SGLT2 inhibition did not attenuate the extent of glomerulosclerosis, tubulointerstitial fibrosis or overexpression of the profibrotic cytokine, transforming growth factor-ß1 mRNA in the kidneys of 5/6 nephrectomised rats. While not precluding beneficial effects in the diabetic setting, these findings indicate that SGLT2 inhibition does not have renoprotective effects in this classical model of progressive non-diabetic CKD

Type I collagen.

<p>Representative sections stained with anti-collagen I antibody revealing minimal immunolablelling in sham rats (A, B) while those from SNX animals (C, D) displayed increased deposition surrounding Bowman’s capsule and in bands of interstitial fibrosis. No difference in immunolabelling was evident between those rats that had or had not received dapagliflozin. Original magnification x 100. Scale bar: 200 μm.</p

Glomerulosclerosis.

<p>Representative glomerular images (A-D) and with quantitative analysis (E) of periodic acid-Schiff stained kidney sections. When compared with animals that had undergone sham surgery (A, B), kidney sections from SNX rats (C, D) show substantial glomerulosclerosis that was similar in vehicle (C) and dapagliflozin-treated rats (D). Original magnification x 400. Scale bars: 50 μm. * p < 0.05 vs. sham-operated animals.</p

Animal characteristic and kidney function parameters.

<p>Animal characteristic and kidney function parameters.</p

Phosphorylated Smad2.

<p>Kidney sections from SNX rats showed abundant nuclear staining for phosphorylated Smad2 in both vehicle and dapagliflozin-treated animals contrasting the dearth of immunopositive cells in sham nephrectomised rats. Original magnification x 160. Scale bar: 100 μm. * p < 0.05 vs. sham-operated animals.</p

Progenitor cell secretory products exert additive renoprotective effects when combined with ace inhibitors in experimental CKD

Hypothesis/introduction: Renal fibrovascular injury often persists in chronic kidney disease patients treated with renin-angiotensin system blockers. Intriguingly, early outgrowth cell-derived factor infusion also inhibits chronic renal injury. We sought to determine whether early outgrowth cell-derived factor administration provides further renoprotection when added to renin-angiotensin system blockade. Materials and methods: Conditioned medium was generated by incubating rat early outgrowth cells with serum-free endothelial basal medium-2 to collect their secreted factors. Subtotal nephrectomy rats received enalapril 0.5 mg/L in drinking water or placebo, beginning 8 weeks post-surgery. Four weeks later, enalapril-treated rats received intravenous injections of either conditioned medium or control endothelial basal medium-2 for 2 weeks. Glomerular filtration rate, urinary protein excretion and renal structure were assessed 4 weeks later at 16 weeks post-surgery. Results: Enalapril-treated subtotal nephrectomy rats receiving control endothelial basal medium-2 injections experienced only partial renoprotection when compared to vehicle-treated subtotal nephrectomy rats. In contrast, conditioned medium infusion, when administered in addition to enalapril, attenuated the progression of renal dysfunction in subtotal nephrectomy rats, improving glomerular filtration rate and reducing proteinuria without affecting blood pressure. Conclusions: Early outgrowth cell-derived factors exert additive renoprotective effects on top of angiotensin-converting enzyme inhibitor therapy in experimental chronic kidney disease, providing the rationale for clinical trials of early outgrowth cell-based therapies for chronic kidney disease

Interstitial fibrosis.

<p>Representative cortical tubulointerstitial images (A-D) and with quantitative analysis (E) of Masson’s trichrome-stained kidney sections. When compared with animals that had undergone sham surgery (A, B), kidney sections from SNX rats (C, D) show substantial interstitial fibrosis (blue) that was similar in vehicle (C) and dapagliflozin-treated rats (D). Original magnification x 100. Scale bar: 200 μm. * p < 0.05 vs. sham-operated animals.</p

Repeated treatment with bone marrow cell secretory products maintains long-term renoprotection in experimental chronic kidney disease: a placebo-controlled trial

Abstract Background Bone marrow-derived early outgrowth cells (EOCs) secrete soluble factors that exert potent renoprotective effects, such that infusion of their conditioned medium recapitulates the affects of the cells themselves. Objectives The objective of this study is to test whether the protective effect of conditioned medium infusion wanes with time and whether tachyphylaxis occurs with repeated administration. Design This is a placebo-controlled animal study. Setting The study was conducted at St. Michael’s Hospital, Toronto, Ontario, Canada. Subjects Fischer 344 (F344) rats were used in this study. Measurements The following were measured: (1) urinary protein:creatinine ratio, (2) glomerular filtration rate, (3) systolic blood pressure, (4) body weight, (5) glomerular endothelial cell density, and (6) glomerular and tubulointerstitial type IV collagen deposition. Methods Subtotally nephrectomized F344 rats, a model of progressive chronic kidney disease, were randomized 4 weeks post-surgery to receive thrice-weekly intravenous injections of concentrated EOC-conditioned medium (EOC CM) or unconditioned medium (UCM) over 2 weeks. Three animal groups were studied, according to whether they were administered conditioned medium: once (Initial Therapy Only group), twice (Repeat Therapy group), or not at all (No Therapy group). Results Following initial therapy, EOC CM-treated animals excreted less urinary protein, a marker of renal injury, than their UCM-treated counterparts. At 10 weeks post-subtotal nephrectomy, however, mean urinary protein excretion in conditioned medium-treated animals was fourfold greater than at the completion of the initial treatment course. At this time point, conditioned medium-treated animals were randomized to receive a second course of either conditioned medium (Repeat Therapy group) or unconditioned medium (Initial Therapy Only group). At study end (14 weeks post-subtotal nephrectomy), Repeat Therapy animals demonstrated higher glomerular filtration rate, less proteinuria, preserved renal microvasculature, and diminished fibrosis when compared with the No Therapy group. Initial Therapy Only animals exhibited an intermediate effect. Limitations Testing the effect of EOC-conditioned medium in a single model of chronic kidney disease (CKD) has limitations. Conclusions These findings suggest that early outgrowth cell-derived factors, while renoprotective, have a limited duration of action. Repeated administration of these factors, however, is able to extend the duration of efficacy and attenuate the progression of experimental chronic kidney disease

Repeated Treatment with Bone Marrow Cell Secretory Products Maintains Long-Term Renoprotection in Experimental Chronic Kidney Disease: A Placebo-Controlled Trial

Background: Bone marrow-derived early outgrowth cells (EOCs) secrete soluble factors that exert potent renoprotective effects, such that infusion of their conditioned medium recapitulates the affects of the cells themselves. Objectives: The objective of this study is to test whether the protective effect of conditioned medium infusion wanes with time and whether tachyphylaxis occurs with repeated administration. Design: This is a placebo-controlled animal study. Setting: The study was conducted at St. Michael's Hospital, Toronto, Ontario, Canada. Subjects: Fischer 344 (F344) rats were used in this study. Measurements: The following were measured: (1) urinary protein:creatinine ratio, (2) glomerular filtration rate, (3) systolic blood pressure, (4) body weight, (5) glomerular endothelial cell density, and (6) glomerular and tubulointerstitial type IV collagen deposition. Methods: Subtotally nephrectomized F344 rats, a model of progressive chronic kidney disease, were randomized 4 weeks post-surgery to receive thrice-weekly intravenous injections of concentrated EOC-conditioned medium (EOC CM) or unconditioned medium (UCM) over 2 weeks. Three animal groups were studied, according to whether they were administered conditioned medium: once (Initial Therapy Only group), twice (Repeat Therapy group), or not at all (No Therapy group). Results: Following initial therapy, EOC CM-treated animals excreted less urinary protein, a marker of renal injury, than their UCM-treated counterparts. At 10 weeks post-subtotal nephrectomy, however, mean urinary protein excretion in conditioned medium-treated animals was fourfold greater than at the completion of the initial treatment course. At this time point, conditioned medium-treated animals were randomized to receive a second course of either conditioned medium (Repeat Therapy group) or unconditioned medium (Initial Therapy Only group). At study end (14 weeks post-subtotal nephrectomy), Repeat Therapy animals demonstrated higher glomerular filtration rate, less proteinuria, preserved renal microvasculature, and diminished fibrosis when compared with the No Therapy group. Initial Therapy Only animals exhibited an intermediate effect. Limitations: Testing the effect of EOC-conditioned medium in a single model of chronic kidney disease (CKD) has limitations. Conclusions: These findings suggest that early outgrowth cell-derived factors, while renoprotective, have a limited duration of action. Repeated administration of these factors, however, is able to extend the duration of efficacy and attenuate the progression of experimental chronic kidney disease