Mauro Gacci

Isolation and Characterization of Multipotent Progenitor Cells from the Bowman’s Capsule of Adult Human Kidneys

Regenerative medicine represents a critical clinical goal for patients with ESRD, but the identification of renal adult multipotent progenitor cells has remained elusive. It is demonstrated that in human adult kidneys, a subset of parietal epithelial cells (PEC) in the Bowmans capsule exhibit coexpression of the stem cell markers CD24 and CD133 and of the stem cell-specific transcription factors Oct-4 and BmI-1, in the absence of lineage-specific markers. This CD24+CD133+ PEC population, which could be purified from cultured capsulated glomeruli, revealed self-renewal potential and a high cloning efficiency. Under appropriate culture conditions, individual clones of CD24+CD133+ PEC could be induced to generate mature, functional, tubular cells with phenotypic features of proximal and/or distal tubules, osteogenic cells, adipocytes, and cells that exhibited phenotypic and functional features of neuronal cells. The injection of CD24+CD133+ PEC but not of CD24-CD133- renal cells into SCID mice that had acute renal failure resulted in the regeneration of tubular structures of different portions of the nephron. More important, treatment of acute renal failure with CD24+CD133+ PEC significantly ameliorated the morphologic and functional kidney damage. This study demonstrates the existence and provides the characterization of a population of resident multipotent progenitor cells in adult human glomeruli, potentially opening new avenues for the development of regenerative medicine in patients who have renal diseases.

Regeneration of Glomerular Podocytes by Human Renal Progenitors

Depletion of podocytes, common to glomerular diseases in general, plays a role in the pathogenesis of glomerulosclerosis. Whether podocyte injury in adulthood can be repaired has not been established. Here, we demonstrate that in the adult human kidney, CD133+CD24+ cells consist of a hierarchical population of progenitors that are arranged in a precise sequence within Bowmans capsule and exhibit heterogeneous potential for differentiation and regeneration. Cells localized to the urinary pole that expressed CD133 and CD24, but not podocyte markers (CD133+CD24+PDX- cells), could regenerate both tubular cells and podocytes. In contrast, cells localized between the urinary pole and vascular pole that expressed both progenitor and podocytes markers (CD133+CD24+PDX+) could regenerate only podocytes. Finally, cells localized to the vascular pole did not exhibit progenitor markers, but displayed phenotypic features of differentiated podocytes (CD133-CD24-PDX+ cells). Injection of CD133+CD24+PDX- cells, but not CD133+CD24+PDX+ or CD133-CD24- cells, into mice with adriamycin-induced nephropathy reduced proteinuria and improved chronic glomerular damage, suggesting that CD133+CD24+PDX- cells could potentially treat glomerular disorders characterized by podocyte injury, proteinuria, and progressive glomerulosclerosis.

Essential but differential role for CXCR4 and CXCR7 in the therapeutic homingof human renal progenitor cells

Recently, we have identified a population of renal progenitor cells in human kidneys showing regenerative potential for injured renal tissue of SCID mice. We demonstrate here that among all known chemokine receptors, human renal progenitor cells exhibit high expression of both stromal-derived factor-1 (SDF-1) receptors, CXCR4 and CXCR7. In SCID mice with acute renal failure (ARF), SDF-1 was strongly up-regulated in resident cells surrounding necrotic areas. In the same mice, intravenously injected renal stem/progenitor cells engrafted into injured renal tissue decreased the severity of ARF and prevented renal fibrosis. These beneficial effects were abolished by blocking either CXCR4 or CXCR7, which dramatically reduced the number of engrafting renal progenitor cells. However, although SDF-1–induced migration of renal progenitor cells was only abolished by an anti-CXCR4 antibody, transendothelial migration required the activity of both CXCR4 and CXCR7, with CXCR7 being essential for renal progenitor cell adhesion to endothelial cells. Moreover, CXCR7 but not CXCR4 was responsible for the SDF-1–induced renal progenitor cell survival. Collectively, these findings suggest that CXCR4 and CXCR7 play an essential, but differential, role in the therapeutic homing of human renal progenitor cells in ARF, with important implications for the development of stem cell–based therapies.

A systematic review and meta-analysis on the use of phosphodiesterase 5 inhibitors alone or in combination with α-blockers for lower urinary tract symptoms due to benign prostatic hyperplasia

CONTEXT Several randomized controlled trials (RCTs) on phosphodiesterase type 5 inhibitors (PDE5-Is) have showed significant improvements in both lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) in men affected by one or both conditions, without a significant increase in adverse events. However, the results are inconsistent. OBJECTIVE Perform a systematic review and meta-analysis of available prospective and cross-sectional studies on the use of PDE5-Is alone or in combination with α1-adrenergic blockers in patients with LUTS/benign prostatic hyperplasia (BPH). EVIDENCE ACQUISITION A systematic search was performed using the Medline, Embase, and Cochrane Library databases through September 2011 including the combination of the following terms: LUTS, BPH, PDE5-Is, sildenafil, tadalafil, vardenafil, udenafil, α-blockers, and α1-adrenergic blocker. The meta-analysis was conducted according to the guidelines for observational studies in epidemiology. EVIDENCE SYNTHESIS Of 107 retrieved articles, 12 were included in the present meta-analysis: 7 on PDE5-Is versus placebo, with 3214 men, and 5 on the combination of PDE5-Is with α1-adrenergic blockers versus α1-adrenergic blockers alone, with 216 men. Median follow-up of all RCTs was 12 wk. Combining the results of those trials, the use of PDE5-Is alone was associated with a significant improvement of the International Index of Erectile Function (IIEF) score (+5.5; p<0.0001) and International Prostate Symptom Score (IPSS) (-2.8; p<0.0001) but not the maximum flow rate (Q(max)) (-0.00; p=not significant) at the end of the study as compared with placebo. The association of PDE5-Is and α1-adrenergic blockers improved the IIEF score (+3.6; p<0.0001), IPSS score (-1.8; p = 0.05), and Q(max) (+1.5; p<0.0001) at the end of the study as compared with α-blockers alone. CONCLUSIONS The meta-analysis of the available cross-sectional data suggests that PDE5-Is can significantly improve LUTS and erectile function in men with BPH. PDE5-Is seem to be a promising treatment option for patients with LUTS secondary to BPH with or without ED.

Characterization of Renal Progenitors Committed Toward Tubular Lineage and Their Regenerative Potential in Renal Tubular Injury

Recent studies implicated the existence in adult human kidney of a population of renal progenitors with the potential to regenerate glomerular as well as tubular epithelial cells and characterized by coexpression of surface markers CD133 and CD24. Here, we demonstrate that CD133+CD24+ renal progenitors can be distinguished in distinct subpopulations from normal human kidneys based on the surface expression of vascular cell adhesion molecule 1, also known as CD106. CD133+CD24+CD106+ cells were localized at the urinary pole of Bowmans capsule, while a distinct population of scattered CD133+CD24+CD106− cells was localized in the proximal tubule as well as in the distal convoluted tubule. CD133+CD24+CD106+ cells exhibited a high proliferative rate and could differentiate toward the podocyte as well as the tubular lineage. By contrast, CD133+CD24+CD106− cells showed a lower proliferative capacity and displayed a committed phenotype toward the tubular lineage. Both CD133+CD24+CD106+ and CD133+CD24+CD106− cells showed higher resistance to injurious agents in comparison to all other differentiated cells of the kidney. Once injected in SCID mice affected by acute tubular injury, both of these populations displayed the capacity to engraft within the kidney, generate novel tubular cells, and improve renal function. These properties were not shared by other tubular cells of the adult kidney. Finally, CD133+CD24+CD106− cells proliferated upon tubular injury, becoming the predominating part of the regenerating epithelium in patients with acute or chronic tubular damage. These data suggest that CD133+CD24+CD106− cells represent tubular‐committed progenitors that display resistance to apoptotic stimuli and exert regenerative potential for injured tubular tissue. STEM CELLS2012;30:1714–1725

Critical analysis of the relationship between sexual dysfunctions and lower urinary tract symptoms due to benign prostatic hyperplasia

CONTEXT This review focuses on the relationship among sexual dysfunction (SD), lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH), and related therapies. OBJECTIVE We reviewed the current literature to provide an overview of current data regarding epidemiology and pathophysiology of SD and LUTS. Moreover, we analysed the impact of currently available therapies of LUTS/BPH on both erectile dysfunction (ED) and ejaculatory dysfunction and the effect of phosphodiesterase type 5 inhibitors (PDE5-Is) in patients with ED and LUTS. EVIDENCE ACQUISITION We conducted a Medline search to identify original articles, reviews, editorials, and international scientific congress abstracts by combining the following terms: benign prostatic hyperplasia, lower urinary tract symptoms, sexual dysfunction, erectile dysfunction, and ejaculatory dysfunction. EVIDENCE SYNTHESIS We conducted a comprehensive analysis of more relevant general population-based and BPH/LUTS or SD clinic-based trials and evaluated the common pathophysiologic mechanisms related to both conditions. In a further step, the overall impact of current BPH/LUTS therapies on sexual life, including phytotherapies, novel drugs, and surgical procedures, was scrutinized. Finally, the usefulness of PDE5-Is in LUTS/BPH was critically analysed, including preclinical and clinical research data as well as possible mechanisms of action that may contribute to the efficacy of PDE5-Is with LUTS/BPH. CONCLUSIONS Community-based and clinical data demonstrate a strong and consistent association between LUTS and ED, suggesting that elderly men with LUTS should be evaluated for SD and vice versa. Pathophysiologic hypotheses regarding common basics of LUTS and SD as discussed in the literature are (1) alteration of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway, (2) enhancement of RhoA-Rho-kinase (ROCK) contractile signalling, (3) autonomic adrenergic hyperactivity, and (4) pelvic atherosclerosis. The most important sexual adverse effects of medical therapies are ejaculation disorders after the use of some α-blockers and sexual desire impairment, ED, and ejaculatory disorders after the use of α-reductase inhibitors. Minimally invasive, conventional, and innovative surgical treatments for BPH may induce both retrograde ejaculation and ED. PDE5-Is have demonstrated significant improvements in both LUTS and ED in men with BPH; combination therapy with PDE5-Is and α1-adrenergic blockers seems superior to PDE5-I monotherapy.

Testosterone protects from metabolic syndrome-associated prostate inflammation: an experimental study in rabbit.

Metabolic syndrome (MetS) and benign prostatic hyperplasia (BPH)/lower urinary tract symptoms (LUTS) are often associated. One of their common denominators is hypogonadism. However, testosterone supplementation is limited by concerns for potential prostatic side effects. The objective was to determine whether MetS-associated prostate alterations are prevented by testosterone supplementation. We used a previously described animal model of MetS, obtained by feeding male rabbits a high-fat diet (HFD) for 12 weeks. Subsets of HFD rabbits were treated with testosterone or with the farnesoid X receptor agonist INT-747. Rabbits fed a standard diet were used as controls. HFD-animals develop hypogonadism and all the MetS features: hyperglycemia, glucose intolerance, dyslipidemia, hypertension, and visceral obesity. In addition, HFD-animals show a prostate inflammation. Immunohistochemical analysis demonstrated that HFD-induced prostate fibrosis, hypoxia, and inflammation. The mRNA expression of several proinflammatory (IL8, IL6, IL1β, and TNFα), T lymphocyte (CD4, CD8, Tbet, Gata3, and ROR γt), macrophage (TLR2, TLR4, and STAMP2), neutrophil (lactoferrin), inflammation (COX2 and RAGE), and fibrosis/myofibroblast activation (TGFβ, SM22α, αSMA, RhoA, and ROCK1/ROCK2) markers was significantly increased in HFD prostate. Testosterone, as well as INT-747, treatment prevented some MetS features, although only testosterone normalized all the HFD-induced prostate alterations. Interestingly, the ratio between testosterone and estradiol plasma level retains a significant, negative, association with all the fibrosis and the majority of inflammatory markers analyzed. These data highlight that testosterone protects rabbit prostate from MetS-induced prostatic hypoxia, fibrosis, and inflammation, which can play a role toward the development/progression of BPH/LUTS.

Notch Activation Differentially Regulates Renal Progenitors Proliferation and Differentiation Toward the Podocyte Lineage in Glomerular Disorders

Glomerular diseases account for 90% of end‐stage kidney disease. Podocyte loss is a common determining factor for the progression toward glomerulosclerosis. Mature podocytes cannot proliferate, but recent evidence suggests that they can be replaced by renal progenitors localized within the Bowmans capsule. Here, we demonstrate that Notch activation in human renal progenitors stimulates entry into the S‐phase of the cell cycle and cell division, whereas its downregulation is required for differentiation toward the podocyte lineage. Indeed, a persistent activation of the Notch pathway induced podocytes to cross the G2/M checkpoint, resulting in cytoskeleton disruption and death by mitotic catastrophe. Notch expression was virtually absent in the glomeruli of healthy adult kidneys, while a strong upregulation was observed in renal progenitors and podocytes in patients affected by glomerular disorders. Accordingly, inhibition of the Notch pathway in mouse models of focal segmental glomerulosclerosis ameliorated proteinuria and reduced podocyte loss during the initial phases of glomerular injury, while inducing reduction of progenitor proliferation during the regenerative phases of glomerular injury with worsening of proteinuria and glomerulosclerosis. Taken altogether, these results suggest that the severity of glomerular disorders depends on the Notch‐regulated balance between podocyte death and regeneration provided by renal progenitors. STEM CELLS 2010; 28:1674–1685.

Human Benign Prostatic Hyperplasia Stromal Cells As Inducers and Targets of Chronic Immuno-Mediated Inflammation

Benign prostatic hyperplasia (BPH), a highly prevalent prostatic condition, could involve an inflammatory component in disease pathogenesis. In this study, we show that human stromal prostate cells obtained from BPH tissue can actively contribute to the inflammatory process by secreting proinflammatory cytokines as well as chemokines able to recruit lymphomonuclear cells and by acting as APCs. BPH cells express all of the TLRs and their ligation leads to the secretion of CXCL8/IL-8, CXCL10, and IL-6. In addition, BPH cells express costimulatory as well as class I and class II MHC molecules, which activate alloreactive CD4+ cells that in turn markedly up-regulate IL-12/IL-23p40 and IL-12p75 secretion by BPH cells. Alloreactive CD4+ cells activated by BPH cells secrete IFN-γ and IL-17. These cytokines up-regulate IL-6, IL-8, and CXCL10 production by BPH cells, creating a positive feedback loop that can amplify inflammation. IL-8 induces autocrine/paracrine proliferation of BPH cells, indicating also a growth-promoting activity of this chemokine in disease pathogenesis. These results show that human BPH cells represent nonprofessional APCs able to induce and sustain chronic inflammatory processes, supporting the relevance of inflammation in BPH pathogenesis.

Phosphodiesterase Type 5 Expression in Human and Rat Lower Urinary Tract Tissues and the Effect of Tadalafil on Prostate Gland Oxygenation in Spontaneously Hypertensive Rats

INTRODUCTION In humans, prostate phosphodiesterase type 5 inhibitors (PDE5) expression was prominently localized in the endothelial and smooth muscle cells of the vascular bed, suggesting a possible action of PDE5 inhibitors (PDE5i) on prostate blood flow. AIM To investigate PDE5 expression in human and rat lower urinary tract (LUT) tissues, including vasculature, and determine the effects of PDE5 inhibition with tadalafil on prostatic blood perfusion. MAIN OUTCOME MEASURES Human vesicular-deferential arteries (which originate from the inferior vesical artery, the main arterial source of blood supply to the bladder and prostate) were analyzed for PDE5 expression and activity. The effects of tadalafil on prostate oxygenation were studied in spontaneously hypertensive rats (SHR), characterized by ischemia/hypoxia of the genitourinary tract. METHODS PDE5 expression was evaluated by quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. SHR were treated with tadalafil (2 mg/kg/day) for 1, 7, or 28 days and compared with untreated SHR and the unaffected counterpart Wistar-Kyoto (WKY) rats. Prostate oxygenation was detected by Hypoxyprobe-1 and hypoxia markers (hypoxia-inducible factor-1α[HIF-1α] and endothelin-1 type B [ETB]) immunostaining. RESULTS Human vesicular-deferential artery expressed high levels of PDE5, similar to corpora cavernosa, immunolocalized in the endothelial and smooth muscle layer. In these arteries, tadalafil inhibited cyclic guanosine monophosphate breakdown (half maximal inhibitory concentration (IC(50) ) in the low nanomolar range, as in corpora cavernosa) and increased the relaxant response to sodium nitroprusside. SHR prostate resulted markedly hypoxic (hypoxyprobe immunopositivity) and positive for HIF-1α and ETB, while tadalafil treatment restored oxygenation to WKY level at each time point. The mRNA expression of the HIF-1α target gene, BCL2/adenovirus E1B 19 kDa interacting protein 3, was significantly increased in SHR prostate and partially restored to WKY level by tadalafil. CONCLUSION Human vesicular-deferential artery is characterized by a high expression and activity of PDE5, which was inhibited by tadalafil in vitro. In SHR, tadalafil increases prostate tissue oxygenation, thus suggesting a possible mechanism through which PDE5i exert beneficial effects on LUT symptoms.