Exogenous mesenchymal stem cells localize to the kidney by means of CD44 following acute tubular injury

Human amniotic fluid stem cell preconditioning improves their regenerative potential

Human amniotic fluid stem (hAFS) cells, a novel class of broadly multipotent stem cells that share characteristics of both embryonic and adult stem cells, have been regarded as promising candidate for cell therapy. Taking advantage by the well-established murine model of acute kidney injury (AKI), we studied the proregenerative effect of hAFS cells in immunodeficient mice injected with the nephrotoxic drug cisplatin. Infusion of hAFS cells in cisplatin mice improved renal function and limited tubular damage, although not to control level, and prolonged animal survival. Human AFS cells engrafted injured kidney predominantly in peritubular region without acquiring tubular epithelial markers. Human AFS cells exerted antiapoptotic effect, activated Akt, and stimulated proliferation of tubular cells possibly via local release of factors, including interleukin-6, vascular endothelial growth factor, and stromal cell-derived factor-1, which we documented in vitro to be produced by hAFS cells. The therapeutic potential of hAFS cells was enhanced by cell pretreatment with glial cell line-derived neurotrophic factor (GDNF), which markedly ameliorated renal function and tubular injury by increasing stem cell homing to the tubulointerstitial compartment. By in vitro studies, GDNF increased hAFS cell production of growth factors, motility, and expression of receptors involved in cell homing and survival. These findings indicate that hAFS cells can promote functional recovery and contribute to renal regeneration in AKI mice via local production of mitogenic and prosurvival factors. The effects of hAFS cells can be remarkably enhanced by GDNF preconditioning.

Mesenchymal stem cell injection ameliorates chronic renal failure in a rat model

CKD (chronic kidney disease) has become a public health problem. The therapeutic approaches have been able to reduce proteinuria, but have not been successful in limiting disease progression. In this setting, cell therapies associated with regenerative effects are attracting increasing interest. We evaluated the effect of MSC (mesenchymal stem cells) on the progression of CKD and the expression of molecular biomarkers associated with regenerative effects. Adult male Sprague-Dawley rats subjected to 5/6 NPX (nephrectomy) received a single intravenous infusion of 0.5×106 MSC or culture medium. A sham group subjected to the same injection was used as the control. Rats were killed 5 weeks after MSC infusion. Dye tracking of MSC was followed by immunofluorescence analysis. Kidney function was evaluated using plasma creatinine. Structural damage was evaluated by H&E (haematoxylin and eosin) staining, ED-1 abundance (macrophages) and interstitial α-SMA (α-smooth muscle actin). Repairing processes were evaluated by functional and structural analyses and angiogenic/epitheliogenic protein expression. MSC could be detected in kidney tissues from NPX animals treated with intravenous cell infusion. This group presented a marked reduction in plasma creatinine levels and damage markers ED-1 and α-SMA (P<0.05). In addition, treated rats exhibited a significant induction in epitheliogenic [Pax-2, bFGF (basic fibroblast growth factor) and BMP-7 (bone morphogenetic protein-7)] and angiogenic [VEGF (vascular endothelial growth factor) and Tie-2] proteins. The expression of these biomarkers of regeneration was significantly related to the increase in renal function. Many aspects of the cell therapy in CKD remain to be investigated in more detail: for example, its safety, low cost and the possible need for repeated cell injections over time. Beyond the undeniable importance of these issues, what still needs to be clarified is whether MSC administration has a real effect on the treatment of this pathology. It is precisely to this point that the present study aims to contribute.

Original article anti-oxidant pathways are stimulated by mesenchymal stromal cells in renal repair after ischemic injury

BACKGROUND AIMS

Ischemia-reperfusion (IR) injury is a common cause of acute renal failure. Bone marrow (BM)-derived mesenchymal stromal cells (MSC) delivered after renal IR are renoprotective, but knowledge of the protective mechanism is still in development. This investigation analyzed the protective molecular mechanisms of MSC, in particular relating to modulated oxidative stress.

METHODS

In vivo and in vitro models of renal IR were analyzed with and without MSC. In vivo, adult male Sprague-Dawley rats were subjected to 40-min unilateral renal IR. Rat BM-derived MSC were administered at 24 h post-IR (IR + MSC). Other groups had IR but no MSC, or MSC but no ischemia (all groups n = 4). Apoptosis, inflammation, oxidative stress and reparative signal transduction molecules or growth factors were studied 4 days post-IR. In vitro, protection by MSC against oxidative stress (0.4 mm hydrogen peroxide) was investigated using rat renal tubular epithelial cells (NRK52E) with or without MSC in co-culture (tissue culture trans-well inserts), followed by similar analyses to the in vivo investigation.

RESULTS

In vivo, kidneys of IR + MSC animals had significantly increased cell proliferation/regeneration (cells positive for proliferating cell nuclear antigen, expression of epidermal growth factor), increased heme-oxygenase-1 (improved cell survival, anti-oxidant) and decreased 8-OHdG (decreased oxidative stress). In vitro, MSC delivered with oxidative stress significantly decreased apoptosis and Bax (pro-apoptotic protein), and increased mitosis and phospho-ERK1/2, thereby minimizing the damaging outcome and maximizing the regenerative effect after oxidative stress.

CONCLUSIONS

The benefits of MSC, in IR, were primarily pro-regenerative, sometimes anti-apoptotic, and novel anti-oxidant mechanisms were identified.

[Preclinical experience in stem cell therapy for digestive tract diseases]

Adult stem cells are multipotent and self-renewing cells that contain several functions; i) migration and homing potential: stem cells can migrate to injured and inflamed tissues. ii) differentiation potential: stem cells which migrated to injured tissues can be differentiated into multiple cell types for repairing and regenerating the tissues. iii) immunomodulatory properties: stem cells, especially mesenchymal stem cells can suppress immune system such as inflammation. All those characteristics might be useful for the treatment of the digestive tract diseases which are complex and encompass a broad spectrum of different pathogenesis. Preclinical stem cell therapy showed some promising results, especially in liver failure, pancreatitis, sepsis, and inflammatory bowel disease. If we can understand more about the mechanism of stem cell action, stem cell therapy can become a promising alternative treatment for refractory digestive disease in the near future. In this review, we summarized current preclinical experiences in diseases of the digestive tract using stem cells. (Korean J Gastroenterol 2011;58:133-138).

Damage-associated molecular patterns (DAMPs) and mesenchymal stem cells: a matter of attraction and excitement

Necrotic cell death is a typical feature of solid tumors leading to the release of necrotic products, also known as damage-associated molecular patterns (DAMPs), that enhance angiogenesis and prime the immune response. Among the DAMPs, particular attention has been focused on the DNA-binding molecule high-mobility group box 1 (HMGB-1) that can act as a chemoattractant and activator of granulocytes. Here, we discuss an article in this issue of the European Journal of Immunology that demonstrates that DAMPs promote both proliferation and trafficking of mesenchymal stem cells (MSCs), identifying HMGB-1 as a key factor in the regulation of these processes. Moreover, the study shows that DAMPs interfere with the expression of the immunosuppressive molecule indoleamine-2,3-dioxygenase in MSCs, and that the biological activity of HMGB-1 toward MSCs is abolished when HMGB-1 is oxidized. Based on the data from this, and other studies, we depict a model in which DAMPs released from necrotic tumor cells attract and stimulate local proliferation of MSCs that differentiate into tumor-associated fibroblasts promoting tumor growth and angiogenesis. Importantly, the hypoxic conditions of the tumor microenvironment may protect DAMPs from oxidation and thereby preserve their functionality.

Mesenchymal stem cells as a therapeutic approach to glomerular diseases: benefits and risks

Most studies using adult stem cells (ASCs) and progenitor cells as potential therapeutics for kidney disorders have been conducted in models of acute kidney injury, where the damage mainly affects the tubulointerstitium. The results are promising, whereas the underlying mechanisms are still being discussed controversially. Glomerular diseases have not received as much attention. Likely reasons include the often insidious onset, rendering the choice of optimal treatment timing difficult, and the fact that chronic diseases may require long-term therapy. In this mini review, we summarize current strategies in adult stem cell-based therapies for glomerular diseases. In addition, we focus on possible side effects of stem cell administration that have been reported recently, that is, profibrotic actions and maldifferentiation of mesenchymal stem cells.

The effects of covalently immobilized hyaluronic acid substrates on the adhesion, expansion, and differentiation of embryonic stem cells for in vitro tissue engineering

We investigated the in vitro effects of the molecular weight (MW) of hyaluronic acid (HA) on the maintenance of the pluripotency and proliferation of murine embryonic stem (ES) cells. High (1000 kDa) or low (4-8 kDa) MW HA was derivatized using an ultraviolet-reactive compound, 4-azidoaniline, and the derivative was immobilized onto cell culture cover slips. Murine ES cells were cultured on these HA surfaces for 5 days. High-MW HA interacted with murine ES cells via CD44, whereas low-MW HA interacted with these cells mostly via CD168. ES cells grown on both high- and low-MW HA appeared undifferentiated after 3 days. However, more cells adhered, proliferated, and exhibited greater amounts of phospho-p42/44 mitogen-activated-protein-kinase on low- compared with high-MW HA. Expression of Oct-3/4 and phosphorylation of STAT3 were enhanced by ES cells on low-MW HA, not on high-MW HA. After release from HA, cells cultured on low-MW HA in the presence of differentiating medium showed enhanced expression of α-SMA or CD31 compared with cells cultured on high-MW HA. It was concluded that low-MW HA substrates were effective in maintaining murine ES cells in a viable and undifferentiated state, which favors their use in the propagation of ES cells for tissue engineering.

Erythropoietin gene-enhanced marrow mesenchymal stromal cells decrease cisplatin-induced kidney injury and improve survival of allogeneic mice

Bone marrow-derived mesenchymal stromal cells (MSCs) are promising for regenerative medicine applications, such as for renoprotection and repair in acute kidney injury (AKI). Erythropoietin (Epo) can also exert cytoprotective effects on various tissues including the kidney. We hypothesized that MSCs gene-enhanced to secrete Epo may produce a significant beneficial effect in AKI. Mouse Epo-secreting MSCs were generated, tested in vitro, and then implanted by intraperitoneal injection in allogeneic mice previously administered cisplatin to induce AKI. Epo-MSCs significantly improved survival of implanted mice as compared to controls (67% survival versus 33% with Vehicle only). Also, Epo-MSCs led to significantly better kidney function as shown by lower levels of blood urea nitrogen (72 ± 9.5 mg/dl versus 131 ± 9.20 mg/dl) and creatinine (74 ± 17 µmol/l versus 148±19.4 µmol/l). Recipient mice also showed significantly decreased amylase and alanine aminotransferase blood concentrations. Kidney sections revealed significantly less apoptotic cells and more proliferating cells. Furthermore, PCR revealed the presence of implanted cells in recipient kidneys, with Epo-MSCs leading to significantly increased expression of Epo and of phosphorylated-Akt (Ser473) (P-Akt) in these kidneys. In conclusion, our study demonstrates that Epo gene-enhanced MSCs exert significant tissue protective effects in allogeneic mice with AKI, and supports the potential use of gene-enhanced cells as universal donors in acute injury.

Differential effects of kidney-lung cross-talk during acute kidney injury and bacterial pneumonia

Acute injuries of the kidney or lung each represent serious, complex clinical problems, and their combination drastically decreases patient survival. However, detailed understanding of interactions between these two organs is scarce. To evaluate this further, we used the folic acid (FA) and myohemoglobinuria models of acute kidney injury (AKI) together with Pseudomonas aeruginosa inhalation to study kidney-lung cross-talk in mice during acute kidney and lung injury. Subgroups of mice received antineutrophil antibody or platelet-depleting serum to assess the role of neutrophil and platelets, respectively. AKI by itself did not cause clinically relevant acute lung injury. Pneumonia was neutrophil dependent, whereas pneumonia-induced AKI was platelet dependent. AKI attenuated pulmonary neutrophil recruitment and worsened pneumonia. Mice with AKI had lower oxygen saturations and greater bacterial load than mice without. Neutrophils isolated from mice with FA-induced AKI also had impaired transmigration and F-actin polymerization in vitro. Thus, during acute kidney and pneumonia-induced lung injury, clinically relevant kidney-lung interactions are both neutrophil and platelet dependent.

Hyaluronan-CD44 interactions as potential targets for cancer therapy

It is becoming increasingly clear that signals generated in tumor microenvironments are crucial to tumor cell behavior, such as survival, progression and metastasis. The establishment of these malignant behaviors requires that tumor cells acquire novel adhesion and migration properties to detach from their original sites and to localize to distant organs. CD44, an adhesion/homing molecule, is a major receptor for the glycosaminoglycan hyaluronan, which is one of the major components of the tumor extracellular matrix. CD44, a multistructural and multifunctional molecule, detects changes in extracellular matrix components, and thus is well positioned to provide appropriate responses to changes in the microenvironment, i.e. engagement in cell-cell and cell-extracellular matrix interactions, cell trafficking, lymph node homing and the presentation of growth factors/cytokines/chemokines to co-ordinate signaling events that enable the cell responses that change in the tissue environment. The potential involvement of CD44 variants (CD44v), especially CD44v4-v7 and CD44v6-v9, in tumor progression has been confirmed for many tumor types in numerous clinical studies. The downregulation of the standard CD44 isoform (CD44s) in colon cancer is postulated to result in increased tumorigenicity. CD44v-specific functions could be caused by their higher binding affinity than CD44s for hyaluronan. Alternatively, CD44v-specific functions could be caused by differences in associating molecules, which may bind selectively to the CD44v exon. This minireview summarizes how the interaction between hyaluronan and CD44v can serve as a potential target for cancer therapy, in particular how silencing CD44v can target multiple metastatic tumors.

Regenerative medicine of the kidney

End stage renal disease is a major health problem in this country and worldwide. Although dialysis and kidney transplantation are currently used to treat this condition, kidney regeneration resulting in complete healing would be a desirable alternative. In this review we focus our attention on current therapeutic approaches used clinically to delay the onset of kidney failure. In addition we describe novel approaches, like Tissue Engineering, Stem cell Applications, Gene Therapy, and Renal Replacement Therapy that may one day be possible alternative therapies for patients with the hope of delaying kidney failure or even stopping the progression of renal disease.

The role of microvesicles in tissue repair

Microvesicles (MVs) are released by almost all cells in resting and activated conditions. First described several years ago, it is only recently that their mechanisms of action are being elucidated, and their potential role in health and disease is drawing increasing attention. The main function of MVs is signaling through specific interactions with target cells and the transferring of gene products. Gaining further insights into the molecular specificity of MVs has allowed identification of the cellular source and may provide new diagnostic tools in the future. Indeed, an increasing body of evidence indicates that MVs are capable of mediating tissue repair in models of acute kidney and liver injury. In this review, we will discuss the mechanisms through which MVs from stem cells may act on target cells and may modify the response to injury. Furthermore, MVs from inflammatory cells are suspected to be involved in various diseases, such as cardiovascular and renal diseases, pathological pregnancy, tumors and sepsis. MVs are no doubt also involved in modulating immunity, and future studies will clarify their functional role in negatively modulating the cell response. Their role in physiological and pathological processes is increasingly appreciated. Depending on the cell source and the condition, MVs may be either beneficial or detrimental to the host. The recognition of their pathogenetic role may suggest new approaches to future therapies.

Peptide nanofibers preconditioned with stem cell secretome are renoprotective

Stem cells may contribute to renal recovery following acute kidney injury, and this may occur through their secretion of cytokines, chemokines, and growth factors. Here, we developed an acellular, nanofiber-based preparation of self-assembled peptides to deliver the secretome of embryonic stem cells (ESCs). Using an integrated in vitro and in vivo approach, we found that nanofibers preconditioned with ESCs could reverse cell hyperpermeability and apoptosis in vitro and protect against lipopolysaccharide-induced acute kidney injury in vivo. The renoprotective effect of preconditioned nanofibers associated with an attenuation of Rho kinase activation. We also observed that the combined presence of follistatin, adiponectin, and secretory leukoprotease during preconditioning was essential to the renoprotective properties of the nanofibers. In summary, we developed a designer-peptide nanofiber that can serve as a delivery platform for the beneficial effects of stem cells without the problems of teratoma formation or limited cell engraftment and viability.

Hyaluronic acid and chondrogenesis of murine bone marrow mesenchymal stem cells in chitosan sponges

OBJECTIVE

To establish the dose-dependent effects of high-molecular-weight hyaluronic acid (HA) supplementation on chondrogenesis by mesenchymal stem cells (MSCs) cultured on chitosan sponges and to determine the extent to which MSC matrix production (chondrogenesis) can be influenced by incorporation of high-molecular-weight HA into chitosan scaffolds.

SAMPLE POPULATION

Murine MSCs derived from a multipotent bone marrow stromal precursor.

PROCEDURES

MSCs were seeded on chitosan and chitosan-HA scaffolds in chondrogenic medium with various HA concentrations. Scanning electron microscopy, fluorescence microscopy (viability assay), and DNA quantification were used to assess cell attachment, distribution, and viability 48 hours after seeding. Constructs were cultured for 3 weeks prior to evaluation of cell distribution and chondrogenic differentiation via histologic evaluation and quantification of DNA, glycosaminoglycan, and collagen II.

RESULTS

48 hours after MSC seeding, cell viability and DNA content were similar among groups. Three weeks after seeding, HA supplementation of the culture medium improved matrix production in a dose-dependent manner, as indicated by matrix glycosaminoglycan and collagen II concentrations. The scaffold composition, however, had no significant effect on matrix production.

CONCLUSIONS AND CLINICAL RELEVANCE

High-molecular-weight HA supplementation in culture medium had a dose-dependent effect on matrix production and thus chondrogenic differentiation of MSCs cultured on chitosan sponges. The addition of HA in the surrounding fluid during chondrogenesis should improve cartilage production and may be useful for producing engineered cartilage tissues.

Homing pathways of mesenchymal stromal cells (MSCs) and their role in clinical applications

Mesenchymal stromal cells (MSCs) have come into focus for an increasing number of cellular therapies. Since most clinical protocols use intravenous application of MSCs, it has become important to understand their trafficking in the bloodstream. Moreover, since relatively little is known where the transplanted MSCs might locate, a better understanding of involved homing mechanisms will likely shed light on how MSCs exert their therapeutic effects. This review focuses on the current knowledge of homing pathways of transplanted MSCs. We describe regulatory signalling molecules and receptors involved. An outlook is given on significance of these findings for the future use of MSCs as a cellular therapeutic.

Hyaluronan as an immune regulator in human diseases

Accumulation and turnover of extracellular matrix components are the hallmarks of tissue injury. Fragmented hyaluronan stimulates the expression of inflammatory genes by a variety of immune cells at the injury site. Hyaluronan binds to a number of cell surface proteins on various cell types. Hyaluronan fragments signal through both Toll-like receptor (TLR) 4 and TLR2 as well as CD44 to stimulate inflammatory genes in inflammatory cells. Hyaluronan is also present on the cell surface of epithelial cells and provides protection against tissue damage from the environment by interacting with TLR2 and TLR4. Hyaluronan and hyaluronan-binding proteins regulate inflammation, tissue injury, and repair through regulating inflammatory cell recruitment, release of inflammatory cytokines, and cell migration. This review focuses on the role of hyaluronan as an immune regulator in human diseases.

Enforced hematopoietic cell E- and L-selectin ligand (HCELL) expression primes transendothelial migration of human mesenchymal stem cells

According to the multistep model of cell migration, chemokine receptor engagement (step 2) triggers conversion of rolling interactions (step 1) into firm adhesion (step 3), yielding transendothelial migration. We recently reported that glycosyltransferase-programmed stereosubstitution (GPS) of CD44 on human mesenchymal stem cells (hMSCs) creates the E-selectin ligand HCELL (hematopoietic cell E-selectin/L-selectin ligand) and, despite absence of CXCR4, systemically administered HCELL(+)hMSCs display robust osteotropism visualized by intravital microscopy. Here we performed studies to define the molecular effectors of this process. We observed that engagement of hMSC HCELL with E-selectin triggers VLA-4 adhesiveness, resulting in shear-resistant adhesion to ligand VCAM-1. This VLA-4 activation is mediated via a Rac1/Rap1 GTPase signaling pathway, resulting in transendothelial migration on stimulated human umbilical vein endothelial cells without chemokine input. These findings indicate that hMSCs coordinately integrate CD44 ligation and integrin activation, circumventing chemokine-mediated signaling, yielding a step 2-bypass pathway of the canonical multistep paradigm of cell migration.

Human marrow-derived mesenchymal stromal cells decrease cisplatin renotoxicity in vitro and in vivo and enhance survival of mice post-intraperitoneal injection

Acute kidney injury (AKI) can occur from the toxic side-effects of chemotherapeutic agents such as cisplatin. Bone marrow-derived mesenchymal stromal cells (MSCs) have demonstrated wide therapeutic potential often due to beneficial factors they secrete. The goal of this investigation was to evaluate in vitro the effect of human MSCs (hMSCs) secretome on cisplatin-treated human kidney cells, and in vivo the consequence of hMSCs intraperitoneal (ip) implantation in mice with AKI. Our results revealed that hMSCs-conditioned media improved survival of HK-2 human proximal tubular cells exposed to cisplatin in vitro. This enhanced survival was linked to increased expression of phosphorylated Akt (Ser473) and was reduced by a VEGF-neutralizing antibody. In vivo testing of these hMSCs established that ip administration in NOD-SCID mice decreased cisplatin-induced kidney function impairment, as demonstrated by lower blood urea nitrogen levels and higher survival. In addition, blood phosphorous and amylase levels were also significantly decreased. Moreover, hMSCs reduced the plasma levels of several inflammatory cytokines/chemokines. Immunohistochemical examination of kidneys showed less apoptotic and more proliferating cells. Furthermore, PCR indicated the presence of hMSCs in mouse kidneys, which also showed enhanced expression of phosphorylated Akt. In conclusion, our study reveals that hMSCs can exert prosurvival effects on renal cells in vitro and in vivo, suggests a paracrine contribution for kidney protective abilities of hMSCs delivered ip, and supports their clinical potential in AKI.

Mesenchymal stem cells in renal function recovery after acute kidney injury: use of a differentiating agent in a rat model

Acute kidney injury (AKI) is a major health care condition with limited current treatment options. Within this context, stem cells may provide a clinical approach for AKI. Moreover, a synthetic compound previously developed, hyaluronan monoesters with butyric acid (HB), able to induce metanephric differentiation, formation of capillary-like structures, and secretion of angiogenic cytokines, was tested in vitro. Thereafter, we investigated the effects of human mesenchymal stem cells from fetal membranes (FMhMSCs), both treated and untreated with HB, after induction of ischemic AKI in a rat model. At reperfusion following 45-min clamping of renal pedicles, each rat was randomly assigned to one of four groups: CTR, PBS, MSC, and MSC-HB. Renal function at 1, 3, 5, and 7 days was assessed. Histological samples were analyzed by light and electron microscopy and renal injury was graded. Cytokine analysis on serum samples was performed. FMhMSCs induced an accelerated renal functional recovery, demonstrated by biochemical parameters and confirmed by histology showing that histopathological alterations associated with ischemic injury were less severe in cell-treated kidneys. HB-treated rats showed a minor degree of inflammation, both at cytokine and TEM analyses. Better functional and morphological recovery were not associated to stem cells' regenerative processes, but possibly suggest paracrine effects on microenvironment that induce retrieval of renal damaged tissues. These results suggest that FMhMSCs could be useful in the treatment of AKI and the utilization of synthetic compounds could enhance the recovery induction ability of cells.

In vivo cell tracking of canine allogenic mesenchymal stem cells administration via renal arterial catheterization and physiopathological effects on the kidney in two healthy dogs

Stem cell therapy is being special premise for various renal diseases. However, there is limited literature on localization and pathologic and functional effects of allogenic mesenchymal stem cells (MSCs) in healthy dogs. Two healthy dogs were included in this study. Canine MSCs (cMSCs) were cultured from canine bone marrow and incubated with superparamagnetic iron oxide (SPIO) for in vivo cell tracking via MR imaging. The dogs were given the MSC (3 × 10(6) cells) into a renal artery via femoral artery catheterization. Follow-up serial renal assessments included ultrasonography and MRI, serum chemistry, urine analysis, and renal clearance tests. The dogs were euthanized at days 8 and 35 respectively for histopathologic evaluation of kidney. Strong hypointensity in MRI was detected in the treated renal cortex the day after cMSCs infusion. However they disappeared from MR image by the 8th day. Of the serum chemistry tests, serum hepatic enzymes (ALT, AST) were significantly elevated for one week after cMSCs treatment. Histopathological findings also revealed infiltration of SPIO-containing cells into the parenchyma of kidney. On 35th day, histopathology, glomerular atrophy, tubular necrosis, and mineralization were found in the subcapsular cortex, with fibrosis of the interstitial tissues. In vivo MRI studies of stem cells were useful in determining the sequential location of stem cells in the renal parenchyma of healthy dogs. Allogenic stem cells administered via renal artery caused inflammation, tubular necrosis, mineralization, and fibrosis without functional complications.

Hepatocyte growth factor modification promotes the amelioration effects of human umbilical cord mesenchymal stem cells on rat acute kidney injury

Human umbilical cord-derived mesenchymal stem cells (hucMSCs) are particularly attractive cells for cellular and gene therapy in acute kidney injury (AKI). Adenovirus-mediated gene therapy has been limited by immune reaction and target genes selection. However, in the present study, we investigated the therapeutic effects of hepatocyte growth factor modified hucMSCs (HGF-hucMSCs) in ischemia/reperfusion-induced AKI rat models. In vivo animal models were generated by subjecting to 60 min of bilateral renal injury by clamping the renal pedicles and then introduced HGF-hucMSCs via the left carotid artery. Our results revealed that serum creatinine and urea nitrogen levels decreased to the baseline more quickly in HGF-hucMSCs-treated group than that in hucMSCs- or green fluorescent protein-hucMSCs-treated groups at 72 h after injury. The percent of proliferating cell nuclear antigen-positive cells in HGF-hucMSCs-treated group was higher than that in the hucMSCs or green fluorescent protein-hucMSCs-treated groups. Moreover, injured renal tissues treated with HGF-hucMSCs also exhibited less hyperemia and renal tubule cast during the recovery process. Immunohistochemistry and living body imaging confirmed that HGF-hucMSCs localize to areas of renal injury. Real-time polymerase chain reaction result showed that HGF-hucMSCs also inhibited caspase-3 and interleukin-1β mRNA expression in injured renal tissues. Western blot also showed HGF-hucMSCs-treated groups had lower expression of interleukin-1β. Terminal deoxynucleotidyl transferase biotin-deoxyuridine triphosphate (dUTP) nick end labeling method indicated that HGF-hucMSCs-treated group had the least apoptosis cells. In conclusion, our findings suggest that HGF modification promotes the amelioration of ischemia/reperfusion-induced rat renal injury via antiapoptotic and antiinflammatory mechanisms; thus, providing a novel therapeutic application for hucMSCs in AKI.

Stem cells derived from human amniotic fluid contribute to acute kidney injury recovery

Stem cells isolated from human amniotic fluid are gaining attention with regard to their therapeutic potential. In this work, we investigated whether these cells contribute to tubular regeneration after experimental acute kidney injury. Cells expressing stem cell markers with multidifferentiative potential were isolated from human amniotic fluid. The regenerative potential of human amniotic fluid stem cells was compared with that of bone marrow-derived human mesenchymal stem cells. We found that the intravenous injection of 3.5 × 10(5) human amniotic fluid stem cells into nonimmune-competent mice with glycerol-induced acute kidney injury was followed by rapid normalization of renal function compared with injection of mesenchymal stem cells. Both stem cell types showed enhanced tubular cell proliferation and reduced apoptosis. Mesenchymal stem cells were more efficient in inducing proliferation than amniotic fluid-derived stem cells, which, in contrast, were more antiapoptotic. Both cell types were found to accumulate within the peritubular capillaries and the interstitium, but amniotic fluid stem cells were more persistent than mesenchymal stem cells. In vitro experiments demonstrated that the two cell types produced different cytokines and growth factors, suggesting that a combination of different mediators is involved in their biological actions. These results suggest that the amniotic fluid-derived stem cells may improve renal regeneration in acute kidney injury, but they are not more effective than mesenchymal stem cells.

Human mesenchymal stem cells modulate cellular immune response to islet antigen glutamic acid decarboxylase in type 1 diabetes

CONTEXT

Mesenchymal stem cells (MSCs) exert an immunosuppressive effect on the immune system. However, studies on the immunomodulatory potential of MSCs in type 1 diabetes are lacking.

OBJECTIVE

We aimed to evaluate whether human MSCs may inhibit in vitro pancreatic islet antigen-specific T cell activation in type 1 diabetes.

DESIGN

Human MSCs were isolated and characterized. Peripheral blood mononuclear cells (PBMCs) were obtained from nine type 1 diabetic patients at disease onset and 13 healthy control subjects. IFN-gamma, IL-10, and IL-4 enzyme-linked immunospot responses of lymphocytes incubated with glutamic acid decarboxylase 65 (GAD65) were investigated in PBMC cultures and PBMC/MSC cocultures. Levels of prostaglandin E2 (PGE2), IFN-gamma, IL-4, and IL-10 in supernatants were measured by ELISA. PGE2 inhibition experiments with NS-398 and indomethacin were also performed.

RESULTS

Five diabetic patients were identified with a positive PBMC IFN-gamma response to GAD65 and negative IL-10 and IL-4 response. PBMC/MSC cocultures resulted in a significant decrease in the number of spots and in detection of IL-4-secreting cells. PGE2 inhibitors abrogated the immune-suppressive effect, indicating an involvement of PGE2 production, and the constitutive production of PGE2 by MSCs was enhanced in PBMC/MSC coculture. Moreover, in GAD-responder patients, GAD-stimulated PBMC/MSC cocultures significantly decreased secretion of IFN-gamma and IL-10 and increased secretion of IL-4.

CONCLUSIONS

These results provide evidence that human MSCs abrogate in vitro a proinflammatory T helper type 1 response to an islet antigenic stimulus in type 1 diabetes. MSCs induce IL-4-producing cells, suggesting a possible switch to an antiinflammatory T helper type 2 signaling of T cells.

Arterially delivered mesenchymal stem cells prevent obstruction-induced renal fibrosis

BACKGROUND

Mesenchymal stem cells (MSCs) hold promise for the treatment of renal disease. While MSCs have been shown to accelerate recovery and prevent acute renal failure in multiple disease models, the effect of MSC therapy on chronic obstruction-induced renal fibrosis has not previously been evaluated.

MATERIALS AND METHODS

Male Sprague-Dawley rats underwent renal artery injection of vehicle or fluorescent-labeled human bone marrow-derived MSCs immediately prior to sham operation or induction of left ureteral obstruction (UUO). One or 4 wk later, the kidneys were harvested and the renal cortex analyzed for evidence of stem cell infiltration, epithelial-mesenchymal transition (EMT) as evidenced by E-cadherin/α-smooth muscle actin (α-SMA) expression and fibroblast specific protein (FSP+) staining, renal fibrosis (collagen content, Masson's trichrome staining), and cytokine and growth factor activity (ELISA and real time RT-PCR).

RESULTS

Fluorescent-labeled MSCs were detected in the interstitium of the kidney up to 4 wk post-obstruction. Arterially delivered MSCs significantly reduced obstruction-induced α-SMA expression, FSP+ cell accumulation, total collagen content, and tubulointerstitial fibrosis, while simultaneously preserving E-cadherin expression, suggesting that MSCs prevent obstruction-induced EMT and renal fibrosis. Exogenous MSCs reduced obstruction-induced tumor necrosis factor-α (TNF-α) levels, but did not alter transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), interleukin-10 (IL-10), fibroblast growth factor (FGF), or hepatocyte growth factor (HGF) expression.

CONCLUSIONS

Human bone marrow-derived MSCs remain viable several weeks after delivery into the kidney and provide protection against obstruction-induced EMT and chronic renal fibrosis. While the mechanism of MSCs-induced renal protection during obstruction remains unclear, our results demonstrate that alterations in TNF-α production may be involved.

Expression of nestin, vimentin, and NCAM by renal interstitial cells after ischemic tubular injury

This work explores the distribution of various markers expressed by interstitial cells in rat kidneys after ischemic injury (35 minutes) during regeneration of S3 tubules of outer stripe of outer medulla (OSOM). Groups of experimental animals (n = 4) were sacrificed every two hours during the first 24 hours post-ischemia as well as 2, 3, 7, 14 days post-ischemia. The occurrence of lineage markers was analyzed on kidney sections by immunohistochemistry and morphometry during the process of tubular regeneration. In postischemic kidneys, interstitial cell proliferation, assessed by 5-bromo-2'-deoxyuridine (BrdU) and Proliferating Cell Nuclear Antigen (PCNA) labeling, was prominent in outer medulla and reach a maximum between 24 and 72 hours after reperfusion. This population was characterized by the coexpression of vimentin and nestin. The density of -Neural Cell Adhesion Molecule (NCAM) positive interstitial cells increased transiently (18-72 hours) in the vicinity of altered tubules. We have also localized a small population of alpha-Smooth Muscle Actin (SMA)-positive cells confined to chronically altered areas and characterized by a small proliferative index. In conclusion, we observed in the postischemic kidney a marked proliferation of interstitial cells that underwent transient phenotypical modifications. These interstitial cells could be implicated in processes leading to renal fibrosis.

Combination stem cell therapy for heart failure

Patients with congestive heart failure (CHF) that are not eligible for transplantation have limited therapeutic options. Stem cell therapy such as autologous bone marrow, mobilized peripheral blood, or purified cells thereof has been used clinically since 2001. To date over 1000 patients have received cellular therapy as part of randomized trials, with the general consensus being that a moderate but statistically significant benefit occurs. Therefore, one of the important next steps in the field is optimization. In this paper we discuss three ways to approach this issue: a) increasing stem cell migration to the heart; b) augmenting stem cell activity; and c) combining existing stem cell therapies to recapitulate a "therapeutic niche". We conclude by describing a case report of a heart failure patient treated with a combination stem cell protocol in an attempt to augment beneficial aspects of cord blood CD34 cells and mesenchymal-like stem cells.

Mesenchymal stem cells as therapeutic tools and gene carriers in liver fibrosis and hepatocellular carcinoma

Mesenchymal stem (stromal) cells (MSCs) are a source of circulating progenitors that are able to generate cells of all mesenchymal lineages and to cover cellular demands of injured tissues. The extent of their transdifferentiation plasticity remains controversial. Cells with MSC properties have been obtained from diverse tissues after purification and expansion in vitro. These cellular populations are heterogeneous and under certain conditions show pluripotent-like properties. MSCs present immunosuppressive and anti-inflammatory features and high migratory capacity toward inflamed or remodeling tissues. In this study we review available data regarding factors and signaling axes involved in the chemoattraction and engraftment of MSCs to an injured tissue or to a tissue undergoing active remodeling. Moreover, experimental evidence in support of uses of MSCs as vehicles of therapeutic genes is discussed. Because of its regenerative capacity and its particular immune properties, the liver is a good model to analyze the potential of MSC-based therapies. Finally, the potential application of MSCs and genetically modified MSCs in liver fibrosis and hepatocellular carcinoma (HCC) is proposed in view of available evidence.

Paracrine/endocrine mechanism of stem cells on kidney repair: role of microvesicle-mediated transfer of genetic information

PURPOSE OF REVIEW

The mechanism of stem cell-induced kidney repair remains controversial. Engraftment of bone marrow-derived stem cells is considered a rare event and several studies point to paracrine/endocrine processes. This review focuses on microvesicle-mediated transfer of genetic information between stem cells and injured tissue as a paracrine/endocrine mechanism.

RECENT FINDINGS

The following findings support a bidirectional exchange of genetic information between stem and injured cells: microvesicles shuttle defined patterns of mRNA and microRNA, are actively released from embryonic and adult stem cells and are internalized by a receptor-mediated mechanism in target cells; transcripts delivered by microvesicles from injured cells may reprogram the phenotype of stem cells to acquire specific features of the tissue; transcripts delivered by microvesicles from stem cells may induce dedifferentiation of cells surviving injury with cell cycle reentry and tissue self-repair.

SUMMARY

Transfer of genetic information from injured cells may explain stem cell functional and phenotypic changes without the need for transdifferentiation into tissue cells. On the contrary, transfer of genetic information from stem cells may redirect altered functions in target cells suggesting that stem cells may repair damaged tissues without directly replacing parenchymal cells.

Activation of CD74 inhibits migration of human mesenchymal stem cells

Therapeutic administration of mesenchymal stem cells (MSCs) by systemic delivery utilizes the innate ability of the cells to home to damaged tissues, but it can be an inefficient process due to a limited knowledge of cellular cues that regulate migration and homing. Our lab recently discovered that a potent pro-inflammatory cytokine, macrophage migration inhibitory factor (MIF), inhibits MSC migration. Because MIF may act on multiple cellular targets, an activating antibody (CD74Ab) was employed in this study to examine the effect of one MIF receptor, CD74 (major histocompatibility complex class II-associated invariant chain), on MSC motility. CD74 activation inhibits in a dose-dependent manner up to 90% of in vitro migration of MSCs at 40 mug/ml CD74Ab (p < 0.001), with consistent effects observed among three MSC donor preparations. A blocking peptide from the C-terminus of CD74 eliminates the effect of CD74Ab on MSCs. This suggests that MIF may act on MSCs, at least in part, through CD74. Late-passage MSCs exhibit less chemokinesis than those at passage 2. However, MSCs remain responsive to CD74 activation during ex vivo expansion: MSC migration is inhibited approximately 2-fold in the presence of 5 microg/ml CD74Ab at passage 9 vs. approximately 3-fold at passage 2 (p < 0.001). Consistent with this result, there were no significant differences in CD74 expression at all tested passages or after CD74Ab exposure. Targeting CD74 to regulate migration and homing potentially may be a useful strategy to improve the efficacy of a variety of MSC therapies, including those that require ex vivo expansion.

Mesenchymal stem cells derived from human umbilical cord ameliorate ischemia/reperfusion-induced acute renal failure in rats

Mesenchymal stem cells (MSCs) are candidates for cell therapy of kidney diseases. However, the application of MSC derived from human umbilical cord (UC-MSC) in treating acute renal failure (ARF) has not been reported. UC-MSCs, 10(6), were transplantated via the left carotid artery into ARF rats which was established by clamping bilateral pedicles for 60 min and reperfusing. Serum creatinine and urea nitrogen decreased 4.8 times and 3.6 times as well as caspase-3 and IL-1beta decreased 5.8 times and 9 times compared to control groups, respectively. The percent of proliferative cell nuclear antigen (PCNA)-positive cells (53% +/- 7.5%) was higher than that in the control groups (17% +/- 4.5%). In addition, the transplanted UC-MSCs could reside in local injury sites, leading to the relief of hyperemia and inflammation, but no obvious transdifferentiation into renal-like cells. The results lay the foundation for further study on the potential application of UC-MSC in human disease.

In vitro differentiation of MSC into cells with a renal tubular epithelial-like phenotype

Bone marrow mesenchymal stem (stromal) cells (MSCs) are shown to differentiate into different renal lineages in in vivo injury models. Nevertheless, the in vitro differentiation of MSCs into a renal tubular epithelial lineage has not been investigated. We hypothesize that the injured renal epithelial cells express renotypic factors that may influence the differentiation of MSCs into a renal tubular epithelial lineage. MSCs were cocultured for up to seven days with injured or uninjured murine cortical tubular renal epithelial cells (MCTs), which are separated by a physical barrier; following the coculture, MSCs were examined for the expression of two renal tubular epithelial-specific markers, kidney-specific cadherin (Ksp-cadherin) and aquaporin-1 (AQP1). MSCs differentiated into a tubular epithelial-like phenotype, as shown by the appearance of Ksp-cadherin and AQP1 by day 7 when cocultured with injured MCTs. Further, MSCs showed tubulogenic characteristics when cocultured in a three-dimensional matrix. Nonetheless, MSCs cultured with the conditioned medium from injured MCTs, cocultured with ureteric bud cells, or treated with nephrogenic factors did not differentiate into renal epithelial cells. Based on our findings, we conclude that MSCs can differentiate into a renal epithelial lineage independent of cell fusion when cocultured with injured renal cells.

Hepatocyte growth factor-mediated attraction of mesenchymal stem cells for apoptotic neuronal and cardiomyocytic cells

Human bone marrow-derived mesenchymal stem cells (MSC) home to injured tissues and have regenerative capacity. In this study, we have investigated in vitro the influence of apoptotic and necrotic cell death, thus distinct types of tissue damage, on MSC migration. Concordant with an increased overall motility, MSC migrated towards apoptotic, but not vital or necrotic neuronal and cardiac cells. Hepatocyte growth factor (HGF) was expressed by the apoptotic cells only. MSC, in contrast, revealed expression of the HGF-receptor, c-Met. Blocking HGF bioactivity resulted in significant reduction of MSC migration. Moreover, recombinant HGF attracted MSC in a dose-dependent manner. Thus, apoptosis initiates chemoattraction of MSC via the HGF/c-Met axis, thereby linking tissue damage to the recruitment of cells with regenerative potential.

Review article: Potential cellular therapies for renal disease: can we translate results from animal studies to the human condition?

The incidence of chronic kidney disease is increasing worldwide, prompting considerable research into potential regenerative therapies. These have included studies to determine whether an endogenous renal stem cell exists in the postnatal kidney and whether non-renal adult stem cells, such as mesenchymal stem cell, can ameliorate renal damage. Such stem cells will either need to be recruited to the damaged kidney to repair the damage in situ or be differentiated into the desired cell type and delivered into the damaged kidney to subsequently elicit repair without maldifferentiation. To date, these studies have largely been performed using experimental and genetic models of renal damage in rodents. The translation of such research into a therapy applicable to human disease faces many challenges. In this review, we examine which animal models have been used to evaluate potential cellular therapies and how valid these are to human chronic kidney disease.

Mechanisms involved in the therapeutic properties of mesenchymal stem cells

Mesenchymal stem cells (MSCs) have been described as being able to give rise to several quite different mesenchymal cell phenotypes. However, the ability to differentiate is not the only characteristic that makes these cells attractive for therapeutic purposes. The secretion of a broad range of bioactive molecules by MSCs, such as growth factors, cytokines and chemokines, constitutes their most biologically significant role under injury conditions. Understanding this intricate secretory activity as well as the properties of MSCs in vivo is central to harnessing their clinical potential. Herein, we identify some of the molecules involved in the paracrine effects of MSCs with a perspective that these cells intrinsically belong to a perivascular niche in vivo, and discuss how this knowledge could be advantageously used in clinical applications.

Application of mesenchymal stromal cells in urological diseases

The application of stem cells and their use in tissue-engineering approaches is emerging in clinical therapeutic intervention strategies. The use of adult stem cells, either autologous or allogenic, does not raise ethical concerns, in contrast to embryonic stem cells. Mesenchymal stromal cells (MSCs) can be easily obtained from bone marrow or from adipose tissue and further expanded in vitro. Due to their differentiation capacity, MSCs are very attractive for tissue engineering purposes. Furthermore, MSCs secrete a variety of mediators that have beneficial effects on the regenerating tissue. In this review we give an insight into stem cell hierarchy, define the properties of MSCs and summarize recent reports of their administration in urological diseases.

Multipotent mesenchymal stromal cell therapy in renal disease and kidney transplantation

Cell therapies aim at differentiation of stem cells into the specific cell type required to repair damaged or destroyed cells or tissues. Over recent years, cell therapy has been introduced in a variety of application areas, including cardiovascular repair, diabetes, musculoskeletal disorders and renal repair. Multipotent mesenchymal stromal cells (MSCs), often referred to as mesenchymal stem cells, are of particular interest as a cell therapy model, as this is one of the few cell types that are on the brink of entering the clinical arena in different areas of application. MSCs can be differentiated in vitro and in vivo into various cell types of mesenchymal origin such as bone, fat and cartilage. They have important effects on the innate and adaptive immune system and possess striking anti-inflammatory properties that make them attractive for potential use in diseases characterized by autoimmunity and inflammation. In addition, MSCs have been shown to migrate to sites of tissue injury and to enhance repair by secreting anti-fibrotic and pro-angiogenic factors. In this review, evidence for the renoprotective mechanisms of MSCs as well as their therapeutic possibilities and potential hazards in acute and chronic renal disease and allograft rejection is summarized.

Molecular mechanisms involved in mesenchymal stem cell migration to the site of acute myocardial infarction

Mesenchymal stem cells or multipotent mesenchymal stromal cells (both referred to as MSC) have been shown in some studies to have a beneficial effect on myocardial recovery after infarct. Current strategies for MSC delivery to heart involve intravenous, intraarterial, and intramuscular delivery. Different routes of MSC delivery and a lack of knowledge of the mechanisms that MSC utilise to migrate in vivo has most likely led to the marked variations in results that have been found. This review aims to summarise the current knowledge of MSC migratory mechanisms and looks to future methods of MSC manipulation prior to delivery in order to enhance MSC migration and engraftment.

Mesenchymal stem cell-based therapy: a new paradigm in regenerative medicine

Mesenchymal stem cells (MSCs), adherent fibroblastoid cells, present in bone marrow and many other tissues can be easily isolated and expanded in vitro. They are capable of differentiating into different cell types such as osteoblasts, chondrocytes, adipocytes, cardiomyocytes, hepatocytes, endothelial cells and neuronal cells. Such immense plasticity coupled with their ability to modulate the activity of immune cells makes them attractive for stem cell-based therapy aimed at treating previously incurable disorders. Preclinical studies have reported successful use of MSCs for delivering therapeutic proteins and repairing defects in a variety of disease models. These studies highlighted the in vivo potential of MSCs and their ability to home to injury sites and modify the microenvironment by secreting paracrine factors to augment tissue repair. Their therapeutic applicability has been widened by genetic modification to enhance differentiation and tissue targeting, and use in tissue engineering. Clinical trials for diseases such as osteogenesis imperfecta, graft-versus-host disease and myocardial infarction have shown some promise, demonstrating the safe use of both allogeneic and autologous cells. However, lack of knowledge of MSC behaviour and responses in vitro and in vivo force the need for basic and animal studies before heading to the clinic. Contrasting reports on immunomodulatory functions and tumorigenicity along with issues such as mode of cell delivery, lack of specific marker, low survival and engraftment require urgent attention to harness the potential of MSC-based therapy in the near future.

Influence of adult mesenchymal stem cells on in vitro vascular formation

The effective delivery of bioactive molecules to wound sites hasten repair. Cellular therapies provide a means for the targeted delivery of a complex, multiple arrays of bioactive factors to wound sites. Thus, the identification of ideal therapeutic populations is an essential aspect of this approach. In vitro assays can provide an important first step toward this goal by selecting populations that are likely suitable for more expensive and time-consuming in vivo assays. In this study, bone marrow-derived mesenchymal stem cells (BM-MSCs) were integrated into a three-dimensional coculture system that supports the development and stabilization of vascular tube-like structures. The presence of a limited number of BM-MSCs resulted in their coalignment with vascular structures, and it further resulted in increased tubule numbers and complexity. Thus, these studies suggest that BM-MSCs functionally interacted with and were attracted to in vitro formed vascular structures. Further, these cells also provided sufficient bioactive factors and matrix molecules to support the formation of tubular arrays and the stabilization of these arrays. This in vitro system provides a means for assessing the function of BM-MSCs in aspects of the angiogenic component of wound repair.

Possible mechanisms of kidney repair

In most adult epithelia the process of replacing damaged or dead cells is maintained through the presence of stem/progenitor cells, which allow epithelial tissues to be repaired following injury. Existing evidence strongly supports the presence of stem cells in the adult kidney. Indeed, recent findings provide evidence in favour of a role for intrinsic renal cells and against a physiological role for bone marrow-derived stem cells in the regeneration of renal epithelial cells. In addition, recent studies have identified a subset of CD24⁺CD133⁺ renal progenitors within the Bowman's capsule of adult human kidney, which provides regenerative potential for injured renal epithelial cells. Intriguingly, CD24⁺CD133⁺ renal progenitors also represent common progenitors of tubular cells and podocytes during renal development. Chronic injury causes dysfunction of the tubular epithelial cells, which triggers the release of fibrogenic cytokines and recruitment of inflammatory cells to injured kidneys. The rapid interposition of scar tissue probably confers a survival advantage by preventing infectious microorganisms from invading the wound, but prevents subsequent tissue regeneration. However, the existence of renal epithelial progenitors in the kidney suggests a possible explanation for the regression of renal lesions which has been observed in experimental animals and even in humans. Thus, manipulation of the wound repair process in order to shift it towards regeneration will probably require the ability to slow the rapid fibrotic response so that renal progenitor cells can allow tissue regeneration rather than scar formation.

Mesenchymal stem cell-derived microvesicles protect against acute tubular injury

Administration of mesenchymal stem cells (MSCs) improves the recovery from acute kidney injury (AKI). The mechanism may involve paracrine factors promoting proliferation of surviving intrinsic epithelial cells, but these factors remain unknown. In the current study, we found that microvesicles derived from human bone marrow MSCs stimulated proliferation in vitro and conferred resistance of tubular epithelial cells to apoptosis. The biologic action of microvesicles required their CD44- and beta1-integrin-dependent incorporation into tubular cells. In vivo, microvesicles accelerated the morphologic and functional recovery of glycerol-induced AKI in SCID mice by inducing proliferation of tubular cells. The effect of microvesicles on the recovery of AKI was similar to the effect of human MSCs. RNase abolished the aforementioned effects of microvesicles in vitro and in vivo, suggesting RNA-dependent biologic effects. Microarray analysis and quantitative real time PCR of microvesicle-RNA extracts indicate that microvesicles shuttle a specific subset of cellular mRNA, such as mRNAs associated with the mesenchymal phenotype and with control of transcription, proliferation, and immunoregulation. These results suggest that microvesicles derived from MSCs may activate a proliferative program in surviving tubular cells after injury via a horizontal transfer of mRNA.

New trends in face rejuvenation by hyaluronic acid injections

BACKGROUND

Injection techniques are growing, thanks to safer and more suitable filling agents. Hyaluronic acid (HA), a biodegradable product, has become the "gold standard" for fillers. With its wide range, it not only improves wrinkles but also restores volume.

METHODS

Since 1996, many patients have been injected for wrinkles, fine lines, and nasolabial folds. For 3 years, more viscous HAs have been launched, allowing us to restore volumes. Some new procedures are described. These can correct anomalies of the chin and of the nose, and allow a betterment of the periocular area by correcting hollow and falling eyebrows.

RESULTS

The use of different HAs for each area and indication is suitable and offers real possibilities to rejuvenate the skin without downtime. Longevity of the correction depends on treated areas, HA used, and on the individual.

CONCLUSION

HAs are safe and suitable for wrinkles and volume restoration, but besides their mechanical properties, they have numerous physiological functions. With the analysis of literature about the action mechanism of HA and its receptors, it is evident that HA also has a stimulating action on different physiological process.

Evaluation of the effect of autologous mesenchymal stem cell injection in a large-animal model of bilateral kidney ischaemia reperfusion injury

OBJECTIVES

Adult mesenchymal stem cells (MSC) have been proven to be of benefit to the kidney in different experimental models of renal injuries. All studies have been performed in valuable rodent models, but the relevance of these results to large mammals and ultimately, to humans remains unknown. Therefore, the aim of this study was to investigate the effect of MSC transplantation in an alternative ovine large-animal model of bilateral kidney ischaemia reperfusion injury.

MATERIAL AND METHODS

Sheep were divided into three groups: one sham-operated group and two groups submitted to renal bilateral ischaemia for 60 min. Animals with ischaemia reperfusion injury were treated with injection of autologous MSCs or with vehicle medium.

RESULTS

The model sheep presented with renal histological manefestations that closely resembled lesions seen in patients. Transplanted MSCs were found in glomeruli but not in tubules and did not express glomerular cell markers (podocin, von Willebrand factor), but functional evaluation showed no beneficial effect of MSC infusion. Morphological and molecular analyses corroborated the functional results. MSCs did not repair kidney parenchyma and failed to modulate cell death and proliferation or cytokine release (tumour necrosis factor-alpha, vascular endothelial growth factor alpha (VEGF-alpha), Bcl-2, caspase).

CONCLUSION

In this unique autologous large-animal model, MSCs did not exhibit reparative or paracrine protective properties.

Stem cell options for kidney disease

Chronic kidney disease (CKD) is increasing at the rate of 6-8% per annum in the US alone. At present, dialysis and transplantation remain the only treatment options. However, there is hope that stem cells and regenerative medicine may provide additional regenerative options for kidney disease. Such new treatments might involve induction of repair using endogenous or exogenous stem cells or the reprogramming of the organ to reinitiate development. This review addresses the current state of understanding with respect to the ability of non-renal stem cell sources to influence renal repair, the existence of endogenous renal stem cells and the biology of normal renal repair in response to damage. It also examines the remaining challenges and asks the question of whether there is one solution for all forms of renal disease.