Life-sparing effect of human cord blood-mesenchymal stem cells in experimental acute kidney injury

Human umbilical cord blood-derived mesenchymal stem cells prevent diabetic renal injury through paracrine action

AIMS

The present study examined renoprotective effect of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSC) in diabetes. NRK-52E cells were utilized to determine the paracrine effect of hUCB-MSC.

METHODS

hUCB was harvested with the mother's consent. MSC obtained from the hUCB were injected through the tail vein. Growth arrested and synchronized NRK-52E cells were stimulated with transforming growth factor-β1 (TGF-β1) in the presence of hUCB-MSC conditioned media.

RESULTS

At 4 weeks after the streptozotocin (STZ) injection, diabetic rats showed significantly increased urinary protein excretion, renal and glomerular hypertrophy, fractional mesangial area, renal expression of TGF-β1 and α-smooth muscle actin, and collagen accumulation but decreased renal E-cadherin and bone morphogenic protein-7 expression, confirming diabetic renal injury. hUCB-MSC effectively prevented diabetic renal injury except renal and glomerular hypertrophy without a significant effect on blood glucose. CM-DiI-labeled hUCB-MSC and immunostaining of PKcs, a human nuclei antigen, confirmed a few engraftment of hUCB-MSC in diabetic kidneys. hUCB-MSC conditioned media inhibited TGF-β1-induced extracellular matrix upregulation and epithelial-to-mesenchymal transition in NRK-52E cells in a concentration-dependent manner.

CONCLUSIONS

These results demonstrate the renoprotective effect of hUCB-MSC in STZ-induced diabetic rats possibly through secretion of humoral factors and suggest hUCB-MSC as a possible treatment modality for diabetic renal injury.

Kidney protection and regeneration following acute injury: progress through stem cell therapy

Acute kidney injury (AKI) is a common clinical entity with high morbidity and mortality rates and ever increasing medical costs. A large number of patients who are hospitalized with morbidities such as diabetes, vascular disease, or chronic kidney disease are at high risk to develop AKI due to ischemic and nephrotoxic insults. The pathophysiology of ischemic and toxic forms of AKI is complex and includes tubular and vascular cell damage and inflammation. Given the seriousness of this essentially therapy-resistant complication, treatment beyond supportive measures and renal replacement therapy is urgently needed. Recent stem cell research has shown promising results, and cell therapy-based interventions are advancing into clinical trials. An example is our phase 1 clinical trial (NCT00733876) in which cardiac surgery patients at high risk of postoperative AKI were treated safely with allogeneic mesenchymal stem cells. Together with the introduction of biomarkers for an earlier and specific AKI diagnosis, currently tested stem cell-based therapies are expected to provide an entirely new class of diagnostic and therapeutic tools.

Renoprotective effect of human umbilical cord-derived mesenchymal stem cells in immunodeficient mice suffering from acute kidney injury

It is unknown whether human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) can improve the renal function of patients suffering from acute kidney injury. Moreover, before beginning clinical trials, it is necessary to investigate this renoprotective effect of hUC-MSCs in a xenogeneic model of acute kidney injury. However, no previous studies have examined the application of hUC-MSCs to immunodeficient mice suffering from acute kidney injury. The objectives of this study were to examine whether hUC-MSCs could improve renal function in nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice suffering from acute kidney injury, and to investigate the mechanism(s) for hUC-MSCs to improve renal function in this xenogeneic model. Early (3 hr) and late (12 hr) administrations of hUC-MSCs (10⁶ cells) were performed via the external jugular vein into NOD-SCID mice suffering from either folic acid (FA) (250 mg/kg body weight) or vehicle. The results showed that early administration of hUC-MSCs improved the renal function of NOD-SCID mice suffering from FA-induced acute kidney injury, as evidenced by decreased serum urea nitrogen and serum creatinine levels, as well as a reduced tubular injury score. The beneficial effects of hUC-MSCs were through reducing apoptosis and promoting proliferation of renal tubular cells. These benefits were independent of inflammatory cytokine effects and transdifferentiation. Furthermore, this study is the first one to show that the reduced apoptosis of renal tubular cells by hUC-MSCs in this xenogeneic model is mediated through the mitochondrial pathway, and through the increase of Akt phosphorylation.

Stem cells for reprogramming: could hUMSCs be a better choice?

Human umbilical cord mesenchymal stem cells (hUMSC) are primitive multipotent cells capable of differentiating into cells of different lineages. They can be an alternative source of pluripotent cells since they are ethically and regulatory approved, are easily obtained and have low immunogenicity compared to embryonic stem cells which are dogged with numerous controversies. hUMSC can be a great source for cell and transplantation therapy.

The alleviation of acute and chronic kidney injury by human Wharton's jelly-derived mesenchymal stromal cells triggered by ischemia-reperfusion injury via an endocrine mechanism

BACKGROUND AIMS

The effects of human Wharton's jelly-derived mesenchymal stromal cells (WJ-MSC) on acute and chronic kidney injury induced by ischemia-reperfusion injury (IRI) were assessed.

METHODS

WJ-MSC were injected intravenously immediately after solitary kidney ischemia for 45 min. Cells were labeled with 5-bromo-2'deoxy-uridine (BrdU) for tracing in vivo. At 48 h post-IRI, serum creatinine and blood urea nitrogen (BUN) were measured. Tubular cell proliferation and apoptosis as well as activation of the Akt signal were identified by immunostaining. Real-time polymerase chain reaction (PCR) was employed to determine gene expression of inflammation-related cytokines and hepatocyte growth factor (HGF). Levels of human HGF were assayed by enzyme-linked immunosorbant assay (ELISA). Twenty-two weeks later, renal fibrosis was assessed by Masson's tri-chrome staining, collagen content and α-smooth muscle actin (α-SMA) staining.

RESULTS

There was no sign of labeled cells residing in the damaged kidney. Acute renal dysfunction elicited by IRI was considerably improved by WJ-MSC, in parallel with a stronger proliferative response and less apoptotic events. Additionally, phosphoAkt staining in injured tubular cells was substantially intensified. Cell treatment also caused a remarkable up-regulation of kidney interleukin (IL)-10, heme oxygenase (HO)-1 and HGF expression. Human HGF was detected in cell supernatants and the serum of cell-infused rats. Moreover, IRI-initiated fibrosis was abrogated by cell therapy, coincident with function amelioration.

CONCLUSIONS

WJ-MSC alleviate acute kidney injury, thereby rescuing the ensuing fibrotic lesions in an endocrine manner. The Akt signal in impaired tubular cells is reinforced by WJ-MSC, facilitating cell resistance to apoptosis and cell proliferation. HGF, either delivered or induced by WJ-MSC, is an important contributor.

A novel strategy to enhance mesenchymal stem cell migration capacity and promote tissue repair in an injury specific fashion

Mesenchymal stem cells (MSCs) of bone marrow origin appear to be an attractive candidate for cell-based therapies. However, the major barrier to the effective implementation of MSC-based therapies is the lack of specific homing of exogenously infused cells and overall the inability to drive them to the diseased or damaged tissue. In order to circumvent these limitations, we developed a preconditioning strategy to optimize MSC migration efficiency and potentiate their beneficial effect at the site of injury. Initially, we screened different molecules by using an in vitro injury-migration setting, and subsequently, we evaluated the effectiveness of the different strategies in mice with acute kidney injury (AKI). Our results showed that preconditioning of MSCs with IGF-1 before infusion improved cell migration capacity and restored normal renal function after AKI. The present study demonstrates that promoting migration of MSCs could increase their therapeutic potential and indicates a new therapeutic paradigm for organ repair.

Detrimental effects of rat mesenchymal stromal cell pre-treatment in a model of acute kidney rejection

Mesenchymal stromal cells (MSC) have shown immunomodulatory and tissue repair potential including partial tolerance induction by pre-treatment of donor-specific cells in a rat heart transplantation model. Very recently, we could show that autologous MSC attenuated ischemia reperfusion injury in a highly mismatched donor–recipient rat kidney transplant model. Therefore, we investigated donor-specific MSC pre-treatment in this rat kidney transplantation model to study whether graft function could be improved, or if tolerance could be induced. Donor- and recipient-type MSC or phosphate buffered saline (PBS) as a control was injected i.v. 4 days before kidney transplantation. Mycophenolate mofetil immunosuppression (20mg/kg body weight) was applied for 7 days. Kidney grafts and spleens were harvested between days 8 and 10 and analyzed by quantitative RT-PCR and immunohistology. In addition, creatinine levels in the blood were measured and serum was screened for the presence of donor-specific antibodies. Surprisingly, application of both donor- and recipient-specific MSC resulted in enhanced humoral immune responses verified by intragraft B cell infiltration and complement factor C4d deposits. Moreover, signs of inflammation and rejection were generally enhanced in both MSC-treated groups relative to PBS control group. Additionally, pre-treatment with donor-specific MSC significantly enhanced the level of donor-specific antibody formation when compared with PBS- or recipient MSC-treated groups. Pre-treatment with both MSC types resulted in a higher degree of kidney cortex tissue damage and elevated creatinine levels at the time point of rejection. Thus, MSC pre-sensitization in this model impairs the allograft outcome. Our data from this pre-clinical kidney transplantation model indicate that pre-operative MSC administration may not be optimal in kidney transplantation and caution must be exerted before moving forward with clinical studies in order to avoid adverse effects.

Mesenchymal stromal cells in renal ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is an inevitable consequence of organ transplantation and a major determinant of patient and graft survival in kidney transplantation. Renal I/R injury can lead to fibrosis and graft failure. Although the exact sequence of events in the pathophysiology of I/R injury remains unknown, the role of inflammation has become increasingly clear. In this perspective, mesenchymal stromal cells (MSCs) are under extensive investigation as potential therapy for I/R injury, since MSCs are able to exert immune regulatory and reparative effects. Various preclinical studies indicate the beneficial effects of MSCs in ameliorating renal injury and accelerating tissue repair. These versatile cells have been shown to migrate to sites of injury and to enhance repair by paracrine mechanisms instead of by differentiating and replacing the injured cells. The first phase I studies of MSCs in human renal I/R injury and kidney transplantation have been started, and results are awaited soon. In this review, preliminary results and opportunities of MSCs in human renal I/R injury are summarized. We might be heading towards a cell-based paradigm shift in the treatment of renal I/R injury.

CD117(+) amniotic fluid stem cells: state of the art and future perspectives

Broadly multipotent stem cells can be isolated from amniotic fluid by selection for the expression of the membrane stem cell factor receptor c-Kit, a common marker for multipotential stem cells. They have clonogenic capability and can be directed into a wide range of cell types representing the three primary embryonic lineages. Amniotic fluid stem cells maintained for over 250 population doublings retained long telomeres and a normal karyotype. Clonal human lines verified by retroviral marking were induced to differentiate into cell types representing each embryonic germ layer, including cells of adipogenic, osteogenic, myogenic, endothelial, neuronal and hepatic lineages. AFS cells could be differentiate toward cardiomyogenic lineages, when co-cultured with neonatal cardiomyocytes, and have the potential to generate myogenic and hematopoietic lineages both in vitro and in vivo. Very recently first trimester AFS cells could be reprogrammed without any genetic manipulation opening new possibilities in the field of fetal/neonatal therapy and disease modeling. In this review we are aiming to summarize the knowledge on amniotic fluid stem cells and highlight the most promising results.

Regenerative medicine as applied to general surgery

The present review illustrates the state of the art of regenerative medicine (RM) as applied to surgical diseases and demonstrates that this field has the potential to address some of the unmet needs in surgery. RM is a multidisciplinary field whose purpose is to regenerate in vivo or ex vivo human cells, tissues, or organs to restore or establish normal function through exploitation of the potential to regenerate, which is intrinsic to human cells, tissues, and organs. RM uses cells and/or specially designed biomaterials to reach its goals and RM-based therapies are already in use in several clinical trials in most fields of surgery. The main challenges for investigators are threefold: Creation of an appropriate microenvironment ex vivo that is able to sustain cell physiology and function in order to generate the desired cells or body parts; identification and appropriate manipulation of cells that have the potential to generate parenchymal, stromal and vascular components on demand, both in vivo and ex vivo; and production of smart materials that are able to drive cell fate.

Pathophysiology of acute kidney injury

Acute kidney injury (AKI) is the leading cause of nephrology consultation and is associated with high mortality rates. The primary causes of AKI include ischemia, hypoxia, or nephrotoxicity. An underlying feature is a rapid decline in glomerular filtration rate (GFR) usually associated with decreases in renal blood flow. Inflammation represents an important additional component of AKI leading to the extension phase of injury, which may be associated with insensitivity to vasodilator therapy. It is suggested that targeting the extension phase represents an area potential of treatment with the greatest possible impact. The underlying basis of renal injury appears to be impaired energetics of the highly metabolically active nephron segments (i.e., proximal tubules and thick ascending limb) in the renal outer medulla, which can trigger conversion from transient hypoxia to intrinsic renal failure. Injury to kidney cells can be lethal or sublethal. Sublethal injury represents an important component in AKI, as it may profoundly influence GFR and renal blood flow. The nature of the recovery response is mediated by the degree to which sublethal cells can restore normal function and promote regeneration. The successful recovery from AKI depends on the degree to which these repair processes ensue and these may be compromised in elderly or chronic kidney disease (CKD) patients. Recent data suggest that AKI represents a potential link to CKD in surviving patients. Finally, earlier diagnosis of AKI represents an important area in treating patients with AKI that has spawned increased awareness of the potential that biomarkers of AKI may play in the future.

Engineered whole organs and complex tissues

End-stage organ failure is a key challenge for the medical community because of the ageing population and the severe shortage of suitable donor organs available. Equally, injuries to or congenital absence of complex tissues such as the trachea, oesophagus, or skeletal muscle have few therapeutic options. A new approach to treatment involves the use of three-dimensional biological scaffolds made of allogeneic or xenogeneic extracellular matrix derived from non-autologous sources. These scaffolds can act as an inductive template for functional tissue and organ reconstruction after recellularisation with autologous stem cells or differentiated cells. Such an approach has been used successfully for the repair and reconstruction of several complex tissues such as trachea, oesophagus, and skeletal muscle in animal models and human beings, and, guided by appropriate scientific and ethical oversight, could serve as a platform for the engineering of whole organs and other tissues.

Human adipose tissue-derived mesenchymal stem cells protect kidneys from cisplatin nephrotoxicity in rats

Cisplatin has multiple cellular targets and modes of action that lead to nephrotoxicity. This suggests novel therapies that act at multiple cisplatin target sites may be effective. We tested whether human adipose tissue-derived mesenchymal stem cells (Ad-MSCs) can affect multiple target sites and protect against cisplatin-induced kidney damage. Rats were divided into four groups: control, infused with Ad-MSCs, injected with cisplatin, and cisplatin followed by infusion of Ad-MSCs. Animal survival and renal function were decreased and histological damage was increased in cisplatin-treated rats at day 3. Infusion of Ad-MSCs ameliorated renal dysfunction and tissue injury caused by cisplatin, leading to increased survival. Apoptotic cell death in the kidney was significantly reduced by infusion of Ad-MSCs. Activation of p53, JNK, and ERK and the expression of inflammation-related molecules were also decreased in the kidney that received Ad-MSCs. Very few Ad-MSCs were detected in the kidney. Conditioned medium from cultured Ad-MSCs had renal-protective functions in vivo and in vitro. Renal dysfunction and tissue damage caused by cisplatin were significantly reduced in rats treated with Ad-MSCs-conditioned medium. The viability of cultured renal proximal tubular cells exposed to cisplatin was also improved by coculture with Ad-MSCs or with conditioned medium. Release of proinflammatory mediators induced by cisplatin was inhibited in coculture with Ad-MSCs. Our results show that human Ad-MSCs exert a paracrine-protective effect on cisplatin nephrotoxicity at multiple target sites and suggest that human Ad-MSCs might be a new therapeutic approach for patients with acute kidney 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.

Human umbilical cord blood mesenchymal stem cells protect mice brain after trauma

OBJECTIVE

To investigate whether human umbilical cord blood mesenchymal stem cells, a novel source of progenitors with multilineage potential: 1) decrease traumatic brain injury sequelae and restore brain function; 2) are able to survive and home to the lesioned region; and 3) induce relevant changes in the environment in which they are infused.

DESIGN

Prospective experimental study.

SETTING

Research laboratory.

SUBJECTS

Male C57Bl/6 mice.

INTERVENTIONS

Mice were subjected to controlled cortical impact/sham brain injury. At 24 hrs postinjury, human umbilical cord blood mesenchymal stem cells (150,000/5 μL) or phosphate-buffered saline (control group) were infused intracerebroventricularly contralateral to the injured side. Immunosuppression was achieved by cyclosporine A (10 mg/kg intraperitoneally).

MEASUREMENTS AND MAIN RESULTS

After controlled cortical impact, human umbilical cord blood mesenchymal stem cell transplantation induced an early and long-lasting improvement in sensorimotor functions assessed by neuroscore and beam walk tests. One month postinjury, human umbilical cord blood mesenchymal stem cell mice showed attenuated learning dysfunction at the Morris water maze and reduced contusion volume compared with controls. Hoechst positive human umbilical cord blood mesenchymal stem cells homed to lesioned tissue as early as 1 wk after injury in 67% of mice and survived in the injured brain up to 5 wks. By 3 days postinjury, cell infusion significantly increased brain-derived neurotrophic factor concentration into the lesioned tissue, restoring its expression close to the levels observed in sham operated mice. By 7 days postinjury, controlled cortical impact human umbilical cord blood mesenchymal stem cell mice showed a nonphagocytic activation of microglia/macrophages as shown by a selective rise (260%) in CD11b staining (a marker of microglia/macrophage activation/recruitment) associated with a decrease (58%) in CD68 (a marker of active phagocytosis). Thirty-five days postinjury, controlled cortical impact human umbilical cord blood mesenchymal stem cell mice showed a decrease of glial fibrillary acidic protein positivity in the scar region compared with control mice.

CONCLUSIONS

These findings indicate that human umbilical cord blood mesenchymal stem cells stimulate the injured brain and evoke trophic events, microglia/macrophage phenotypical switch, and glial scar inhibitory effects that remodel the brain and lead to significant improvement of neurologic outcome.

Integration potential of mouse and human bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a multipotent cell population which has been described to exert renoprotective and regenerative effects in experimental models of kidney injury. Several lines of evidence indicate that MSCs also have the ability to contribute to nephrogenesis, suggesting that the cells can be employed in stem cell-based applications aimed at de novo renal tissue generation. In this study we re-evaluate the capacity of mouse and human bone marrow-derived MSCs to contribute to the development of renal tissue using a novel method of embryonic kidney culture. Although MSCs show expression of some genes involved in renal development, their contribution to nephrogenesis is very limited in comparison to other stem cell types tested. Furthermore, we found that both mouse and human MSCs have a detrimental effect on the ex vivo development of mouse embryonic kidney, this effect being mediated through a paracrine action. Stimulation with conditioned medium from a mouse renal progenitor population increases the ability of mouse MSCs to integrate into developing renal tissue and prevents the negative effects on kidney development, but does not appear to enhance their ability to undergo nephrogenesis.

Potential of mesenchymal stem cells in the repair of tubular injury

Current interventions for the treatment of acute kidney injury (AKI) are not satisfactory, and it is time to approach new strategies in order to definitely take a step forward. At its beginning, cell therapy was innovative and promising. We have shown that mesenchymal stem cells (MSCs), isolated from human and murine bone marrow (BM), behave as an efficacious tool for the treatment of cisplatin-induced AKI in mice in terms of amelioration of renal function and structure, and animal survival. Although the mechanism has not been completely elucidated, we have provided data showing that BM-MSC-mediated renal recovery involves the release at the site of injury of the growth factor, insulin-like growth factor-1. Several biological effects have been observed in renal tissues of mice treated with BM-MSCs, including increased cell proliferation, hemodynamic changes, and cell apoptosis reduction. In the same experimental model, we have tested the effect of MSCs isolated from cord blood (CB-MSCs), which, similar to BM-MSCs, not only ameliorated renal function but also protected animals from death to a remarkably higher extent. Animals receiving CB-MSCs showed reduction of oxidative stress and activation of AKT prosurvival pathway in tubular cells. These results hold great promise for future studies in patients with AKI.

The role of multipotent marrow stromal cells (MSCs) in tissue regeneration

An extensive body of preclinical and clinical data has shown that administration of adult multipotent marrow stromal cells (MSCs) effectively ameliorates experimental and clinical conditions of many different organ systems. Differentiation into organ parenchymal cells, however, is very rare, and the main mechanism for organ protection and regeneration from different types of injury is the exertion of paracrine effects and stimulation of tissue repair. A large number of clinical trials have been conducted and are ongoing to investigate the safety and efficacy of MSCs in different organs after various types of organ injury. This article intends to give a brief overview about current applications of MSCs and mechanisms involved in organ protection and regeneration.

Stem cell update: highlights from the 2010 Lugano Stem Cell Meeting

The 2010 edition of the Lugano Stem Cell Meeting, under the auspices of the Swiss center of excellence in cardiovascular diseases "Cardiocentro Ticino" and the Swiss Stem Cell Foundation, offered an update on clinical, translational, and biotechnological advances in regenerative science and medicine pertinent to cardiovascular applications. Highlights from the international forum ranged from innate mechanisms of heart repair, safety, and efficacy of ongoing and completed clinical trials, novel generations of stem cell biologics, bioengineered platforms, and regulatory processes. In the emerging era of regenerative medicine, accelerating the critical path from discovery to product development will require integrated multidisciplinary teams to ensure timely translation of new knowledge into validated algorithms for practice adoption.

Perivascular ancestors of adult multipotent stem cells

Independent studies by numerous investigators have shown that it is possible to harvest multipotent progenitor cells from diverse dissociated and cultured fetal, perinatal, and principally adult developed tissues. Despite the increasingly recognized medical value of these progenitor cells, the archetype of which remains the mesenchymal stem cell, this indirect extraction method has precluded the understanding of their native identity, tissue distribution, and frequency. Consistent with other researchers, we have hypothesized that blood vessels in virtually all organs harbor ubiquitous stem cells. We have identified, marked, and sorted to homogeneity by flow cytometry endothelial and perivascular cells in a large selection of human fetal, perinatal, and adult organs. Perivascular cells, including pericytes in the smallest blood vessels and adventitial cells around larger ones, natively express mesenchymal stem cell markers and produce in culture a long-lasting progeny of multilineage mesodermal progenitor cells. Herein, we review results from our and other laboratories that suggest a perivascular origin for mesenchymal stem cells and other adult progenitor cells. Recent experiments illustrate the therapeutic potential of human pericytes to regenerate skeletal muscle and promote functional recovery in the diseased heart and kidney.