Therapeutic potentials of mesenchymal stem cells in the treatment of inflammatory bowel disease in rats

Interleukin-1beta (IL-1β) and interleukin-17A (IL-17A) have strong pro-inflammatory activities that are involved in inflammatory bowel diseases (IBDs). Mesenchymal stem cell (MSC) therapy is considered a promising treatment for IBD. This study was performed to understand the role of rat Nlrp3 inflammasome, Hmgb1, and pro-inflammatory cytokines (IL-1β and IL-17a) in the pathogenesis of IBD. Also, to evaluate the role of human umbilical cord blood-MSCs (hUCB-MSCs) in the management of IBD. The rats were in four groups: normal controls, indomethacin-induced IBD group, indomethacin-induced IBD rats that received phosphate-buffered saline (PBS), and the IBD group that received hUCB-MSCs as a treatment. The messenger RNA (mRNA) expression levels of rat Nlrp3, Hmgb1, IL-1β, and IL-17a were evaluated by quantitative real-time polymerase chain reaction. Histopathological examination of the small intestinal tissues of the studied rats was performed. There was a significant upregulation of the rat Nlrp3, IL-1β, IL-17a mRNA expression (p < 0.001 for the three parameters), and Hmgb1 (p < 0.05) in the untreated IBD group compared to the normal control group. In the MSC-treated group, IL-1β, IL-17a, and rat Nlrp3 mRNA expression significantly decreased compared to both the untreated IBD group and PBS group (p < 0.05 for all). hUCB-MSCs ameliorated IBD in rats by downregulating the pro-inflammatory cytokines (IL-1β and IL-17a) and other inflammatory mediators such as Hmgb1 and rat Nlrp3.

Optimisation of a Method for the Differentiation of Human Umbilical Cord-derived Mesenchymal Stem Cells Toward Renal Epithelial-like Cells

Human umbilical cord-derived mesenchymal stem cells (hucMSCs) can differentiate into multiple cell lineages, but few methods have been developed to generate kidney lineage cells. Due to their human origin, pluripotent nature and immunomodulatory properties, these stem cells are attractive candidates for clinical applications such as the repair or regeneration of damaged organs. This study evaluated the renal differentiation potential of hucMSCs, when exposed for 10 days to optimised concentrations of retinoic acid, activin-A and bone morphogenetic protein-7 (BMP-7) in various combinations, with and without the priming of the cells with a Wnt signalling pathway activator (CHIR99021). The hucMSCs were isolated and characterised according to surface marker expression (CD73, CD90, CD44, CD146 and CD8) and tri-lineage differentiation potential. The expression of key marker genes (OSR1, TBXT, HOXA13, SIX2, PAX2, KRT18 and ZO1) was examined by qRT-PCR. Specific marker protein expression (E-cadherin, cytokeratin-8 and cytokeratin-19) was analysed by immunocytochemistry. CHIR99021-primed cells treated with the retinoic acid, activin-A and BMP-7 cocktail showed epithelial cell-like differentiation - i.e. distinct phenotypic changes, as well as upregulated gene and protein expression, were observed that were consistent with an epithelial cell phenotype. Thus, our results showed that hucMSCs can efficiently differentiate into renal epithelial-like cells. This work may help in the development of focused therapeutic strategies, in which lineage-defined human stem cells can be used for renal regeneration.

Mesenchymal Stem Cells and Their Exocytotic Vesicles

Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.

Enhancing the Therapeutic Potential of Mesenchymal Stromal Cell-Based Therapies with an Anti-Fibrotic Agent for the Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) affects 1 in 10 members of the general population, placing these patients at an increasingly high risk of kidney failure. Despite the significant burden of CKD on various healthcare systems, there are no effective cures that reverse or even halt its progression. In recent years, human bone-marrow-derived mesenchymal stromal cells (BM-MSCs) have been recognised as a novel therapy for CKDs, owing to their well-established immunomodulatory and tissue-reparative properties in preclinical settings, and their promising safety profile that has been demonstrated in patients with CKDs from several clinical trials. However, renal fibrosis (scarring), a hallmark of CKD, has been shown to impair the viability and functionality of BM-MSCs post-transplantation. This has suggested that BM-MSCs might require a pre-treatment or adjunct therapy that can enhance the viability and therapeutic efficacy of these stromal cells in chronic disease settings. To address this, recent studies that have combined BM-MSCs with the anti-fibrotic drug serelaxin (RLX), have demonstrated the enhanced therapeutic potential of this combination therapy in normotensive and hypertensive preclinical models of CKD. In this review, a critical appraisal of the preclinical data available on the anti-fibrotic and renoprotective actions of BM-MSCs or RLX alone and when combined, as a treatment option for normotensive vs. hypertensive CKD, is discussed.

Stem Cell-Derived Extracellular Vesicles as Potential Therapeutic Approach for Acute Kidney Injury

Acute kidney injury is a frequent complication of hospitalized patients and significantly increases morbidity and mortality, worsening costs and length of hospital stay. Despite this impact on healthcare system, treatment still remains only supportive (dialysis). Stem cell-derived extracellular vesicles are a promising option as they recapitulate stem cells properties, overcoming safety issues related to risks or rejection or aberrant differentiation. A growing body of evidence based on pre-clinical studies suggests that extracellular vesicles may be effective to treat acute kidney injury and to limit fibrosis through direct interference with pathogenic mechanisms of vascular and tubular epithelial cell damage. We herein analyze the state-of-the-art knowledge of therapeutic approaches with stem cell-derived extracellular vesicles for different forms of acute kidney injury (toxic, ischemic or septic) dissecting their cytoprotective, regenerative and immunomodulatory properties. We also analyze the potential impact of extracellular vesicles on the mechanisms of transition from acute kidney injury to chronic kidney disease, with a focus on the pivotal role of the inhibition of complement cascade in this setting. Despite some technical limits, nowadays the development of therapies based on stem cell-derived extracellular vesicles holds promise as a new frontier to limit acute kidney injury onset and progression.

Development of a decellularized hypopharynx with vascular pedicle scaffold for use in reconstructing hypopharynx

BACKGROUND

Hypopharynx reconstruction after hypopharyngectomy is still a great challenge. Perfusion decellularization is for extracellular matrix (ECM) scaffolding and had been used in organ reconstruction. Our study aimed to prepare an acellular, natural, three-dimensional biological hypopharynx with vascular pedicle scaffold as the substitute materials to reconstruct hypopharynx.

RESULT

Scanning electron microscope and histology staining showed that the decellularized hypopharynx with vascular pedicle scaffold retained intact native anatomical ECM structure. Myoblasts were observed on the recellularized scaffolds with bone marrow mesenchymal stem cells induced by 5-azacytidine implanted in the rabbit greater omentum by immunohistochemical analysis.

CONCLUSION

The decellularized hypopharynx with vascular pedicle scaffold prepared by detergent perfusion in our study has a potential to be an alternative material to pharynx reconstruction.

Kidney Microcirculation as a Target for Innovative Therapies in AKI

Acute kidney injury (AKI) is a serious multifactorial conditions accompanied by the loss of function and damage. The renal microcirculation plays a crucial role in maintaining the kidney’s functional and structural integrity for oxygen and nutrient supply and waste product removal. However, alterations in microcirculation and oxygenation due to renal perfusion defects, hypoxia, renal tubular, and endothelial damage can result in AKI and the loss of renal function regardless of systemic hemodynamic changes. The unique structural organization of the renal microvasculature and the presence of autoregulation make it difficult to understand the mechanisms and the occurrence of AKI following disorders such as septic, hemorrhagic, or cardiogenic shock; ischemia/reperfusion; chronic heart failure; cardiorenal syndrome; and hemodilution. In this review, we describe the organization of microcirculation, autoregulation, and pathophysiological alterations leading to AKI. We then suggest innovative therapies focused on the protection of the renal microcirculation and oxygenation to prevent AKI.

Mesenchymal stromal cell treatment of donor kidneys during ex vivo normothermic machine perfusion: A porcine renal autotransplantation study

Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine autotransplantation model, and examine potential MSC treatment-associated kidney improvements up to 14 days posttransplant. After 75 min of kidney warm ischemia, four experimental groups of n = 7 underwent 14 h of oxygenated hypothermic machine perfusion. In three groups this was followed by 240 min of NMP with infusion of vehicle, 10 million porcine, or 10 million human adipose-derived MSCs. All kidneys were autotransplanted after contralateral nephrectomy. MSC treatment did not affect perfusion hemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14 days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short posttransplant follow-up period, no beneficial effects of ex vivo MSC therapy could be demonstrated.

Mesenchymal Stem Cells Attenuates TGF-β1-Induced EMT by Increasing HGF Expression in HK-2 Cells

Background:

Mesenchymal stem cells (MSCs) have recently shown promise for the treatment of various types of chronic kidney disease models. However, the mechanism of this effect is still not well understood. Our study is aimed to investigate the effect of MSCs on transforming growth factor beta 1 (TGF-β1)-induced epithelial mesenchymal transition (EMT) in renal tubular epithelial cells (HK-2 cells) and the underlying mechanism related to the reciprocal balance between hepatocyte growth factor (HGF) and TGF-β1.

Methods:

Our study was performed at Ningbo University, Ningbo, Zhejiang, China between Mar 2017 and Jun 2018. HK-2 cells were initially treated with TGF-β1, then co-cultured with MSCs. The induced EMT was assessed by cellular morphology and the expressions of alpha-smooth muscle actin (α-SMA) and EMT-related proteins. MTS assay and flow cytometry were employed to detect the effect of TGF-β1 and MSCs on HK-2 cell proliferation and apoptosis. SiRNA against hepatocyte growth factor (siHGF) was transfected to decrease the expression of HGF to identify the role of HGF in MSCs inhibiting HK-2 cells EMT.

Results:

Overexpressing TGF-β1 decreased HGF expression, induced EMT, suppressed proliferation and promoted apoptosis in HK-2 cells; but when co-cultured with MSCs all the outcomes were reversed. However, after treated with siHGF, all the benefits taken from MSCs vanished.

Conclusion:

TGF-β1 was a motivating factor of kidney cell EMT and it suppressed the HGF expression. However, MSCs provided protection against EMT by increasing HGF level and decreasing TGF-β1 level. Our results also demonstrated HGF is one of the critical factor in MSCs anti- fibrosis.

Human umbilical cord MSC-derived hepatocyte growth factor enhances autophagy in AOPP-treated HK-2 cells

Mesenchymal stem cell (MSC) transplantation may serve as an important treatment modality in chronic kidney disease (CKD); however, the underlying mechanisms remain unclear. Advanced oxidation protein products (AOPP) have been demonstrated to induce renal tubular epithelial cell (RTEC) injury via autophagy inhibition. Therefore, the present study was performed to investigate the role of human umbilical cord-derived MSCs (hUC-MSCs) in RTEC autophagy. AOPP-treated HK-2 cells were co-cultured with hUC-MSCs or treated with recombinant humanized hepatocyte growth factor (HGF). Western blotting was used to detect the levels of autophagy-and PI3K/AKT/mTOR signaling pathway-related proteins, and immunofluorescence staining was used to detect the levels of autophagy-related proteins. The HGF protein levels in HK-2 cells and the hUC-MSC co-culture system were measured. The cells were subsequently treated with tivantinib, an HGF competitive inhibitor, and the levels of autophagy-related proteins were detected. Microtubule-associated protein 1 light chain 3B (LC3B) II/LC3B I (LC3II/LC3I) and beclin 1 protein levels were increased, while p62, PI3K, phosphorylated (p)-AKT and the p-mTOR protein levels were decreased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP only. Furthermore, HGF expression was increased in AOPP-treated HK-2 cells co-cultured with hUC-MSC, compared with the group treated with AOPP alone. When HGF activity was inhibited using tivantinib, these effects on LC3II/LC3I, beclin 1, p62, PI3K, p-AKT, and p-mTOR expression were partially reversed. Furthermore, the effects of tivantinib were reversed by Ly294002. In conclusion, the present study revealed that hUC-MSCs partially reversed AOPP-mediated inhibition of autophagy in HK-2 cells via secretion of HGF, indicating that hUC-MSCs may serve as a potential therapy for preventing the progression of CKD.

Mesenchymal stem cells and mesenchymal stem cell-derived extracellular vesicles: Potential roles in rheumatic diseases

BACKGROUND

Mesenchymal stem cells (MSCs) have been widely investigated in rheumatic disease due to their immunomodulatory and regenerative properties. Recently, mounting studies have implicated the therapeutic potency of MSCs mostly due to the bioactive factors they produce. Extracellular vesicles (EVs) derived from MSCs have been identified as a promising cell-free therapy due to low immunogenicity. Rheumatic disease, primarily including rheumatoid arthritis and osteoarthritis, is a group of diseases in which immune dysregulation and chronic progressive inflammation lead to irreversible joint damage. Targeting MSCs and MSC-derived EVs may be a more effective and promising therapeutic strategy for rheumatic diseases.

AIM

To evaluate the potential therapeutic effectiveness of MSCs and EVs generated from MSCs in rheumatic diseases.

METHODS

PubMed was searched for the relevant literature using corresponding search terms alone or in combination. Papers published in English language from January 1999 to February 2020 were considered. Preliminary screening of papers concerning analysis of "immunomodulatory function" or "regenerative function" by scrutinizing the titles and abstracts of the literature, excluded the papers not related to the subject of the article. Some other related studies were obtained by manually retrieving the reference lists of papers that comply with the selection criteria, and these studies were screened to meet the final selection and exclusion criteria.

RESULTS

Eighty-six papers were ultimately selected for analysis. After analysis of the literature, it was found that both MSCs and EVs generated from MSCs have great potential in multiple rheumatic diseases, such as rheumatoid arthritis and osteoarthritis, in repair and regeneration of tissues, inhibition of inflammatory response, and regulation of body immunity via promoting chondrogenesis, regulating innate and adaptive immune cells, and regulating the secretion of inflammatory factors. But EVs from MSCs exhibit much more advantages over MSCs, which may represent another promising cell-free restorative strategy. Targeting MSCs and MSC-derived EVs may be a more efficient treatment for patients with rheumatic diseases.

CONCLUSION

The enormous potential of MSCs and EVs from MSCs in immunomodulation and tissue regeneration offers a new idea for the treatment of rheumatism. However, more in-depth exploration is needed before their clinical application.

Emerging Role of Mesenchymal Stem Cell-derived Exosomes in Regenerative Medicine

BACKGROUND

Recent studies have shown the great value of cell therapy over the past few decades. Mesenchymal stem cells (MSCs) have been reported to treat various degenerative diseases not through their differentiation potential but through their paracrine factors of the extracellular vesicle (EV) including exosomes. Exosomes are nanosized (70~150 nm) membrane-bound extracellular vesicles, not only involved in cell-to-cell communication but also in the development of tissue injury repair.

OBJECTIVE

As more researchers proved the enormous potential of exosomes in the field of repairing damaged tissue currently, it is urgent to explore the concrete mechanism and make exosomes to be a practical treatment tool in clinical medicine. In our study, we analyzed and summarized the work on tissue repair via exosomes in order to give some suggestions about the application of exosomes in clinical reality in the future.

RESULTS

MSC-derived exosomes (MSC-Ex) contain a wide variety of functional proteins, mRNAs, miRNAs and signaling lipids. Compared with their parent cells, MSC-Ex are more stable and can reduce the inherent safety risks in administering viable cells such as the risk of occlusion in microvasculature. MSC-Ex can be used to develop a cell-free exosome-based therapy for regenerative medicine, and may provide an alternative to MSC-based therapy.

CONCLUSION

This review summarizes the most recent knowledge of therapeutic potential of MSC-Ex in the liver, heart, kidney, bone, brain diseases and cancer, as well as their associated challenges and opportunities.

Recent Updates on Mesenchymal Stem Cell Based Therapy for Acute Renal Failure

Acute kidney injury, formerly known as acute renal failure, is a pathological condition in which ischemia or toxic damage contributes to the loss of renal proximal tubule epithelial cells. Pathophysiological events such as oxidative stress, mitochondrial dysfunction, and direct renal tubular epithelial cells toxicity are responsible for the progression of the disease. This devastating decline in renal function affects mostly patients in the intensive care units and requires costly and invasive treatments such as dialysis and organ transplant. Fortunately, recent therapies such as the use of mesenchymal stem cells (MSCs) were proven to be effective in ameliorating renal failure via paracrine and immunomodulatory mechanisms. These fibroblast-like adult stem cells that differentiate multilineagely can be isolated from dental pulps, umbilical cords, amniotic fluids, adipose tissues, and bone marrows. Depending on their sources, the therapeutical application of each MSC type has its own capacities, advantages, and drawbacks. The review discusses and compares the latest research studies on the use of different MSCs sources to treat renal failure. Concerns about the future clinical application of MSCs such as homing, toxicity, and the risk of immune rejection are also highlighted.

Substrate Stiffness Modulates Renal Progenitor Cell Properties via a ROCK-Mediated Mechanotransduction Mechanism

Stem cell (SC)-based tissue engineering and regenerative medicine (RM) approaches may provide alternative therapeutic strategies for the rising number of patients suffering from chronic kidney disease. Embryonic SCs and inducible pluripotent SCs are the most frequently used cell types, but autologous patient-derived renal SCs, such as human CD133+CD24+ renal progenitor cells (RPCs), represent a preferable option. RPCs are of interest also for the RM approaches based on the pharmacological encouragement of in situ regeneration by endogenous SCs. An understanding of the biochemical and biophysical factors that influence RPC behavior is essential for improving their applicability. We investigated how the mechanical properties of the substrate modulate RPC behavior in vitro. We employed collagen I-coated hydrogels with variable stiffness to modulate the mechanical environment of RPCs and found that their morphology, proliferation, migration, and differentiation toward the podocyte lineage were highly dependent on mechanical stiffness. Indeed, a stiff matrix induced cell spreading and focal adhesion assembly trough a Rho kinase (ROCK)-mediated mechanism. Similarly, the proliferative and migratory capacity of RPCs increased as stiffness increased and ROCK inhibition, by either Y27632 or antisense LNA-GapmeRs, abolished these effects. The acquisition of podocyte markers was also modulated, in a narrow range, by the elastic modulus and involved ROCK activity. Our findings may aid in 1) the optimization of RPC culture conditions to favor cell expansion or to induce efficient differentiation with important implication for RPC bioprocessing, and in 2) understanding how alterations of the physical properties of the renal tissue associated with diseases could influenced the regenerative response of RPCs.

Biological functions of mesenchymal stem cells and clinical implications

Mesenchymal stem cells (MSCs) are isolated from multiple biological tissues-adult bone marrow and adipose tissues and neonatal tissues such as umbilical cord and placenta. In vitro, MSCs show biological features of extensive proliferation ability and multipotency. Moreover, MSCs have trophic, homing/migration and immunosuppression functions that have been demonstrated both in vitro and in vivo. A number of clinical trials are using MSCs for therapeutic interventions in severe degenerative and/or inflammatory diseases, including Crohn's disease and graft-versus-host disease, alone or in combination with other drugs. MSCs are promising for therapeutic applications given the ease in obtaining them, their genetic stability, their poor immunogenicity and their curative properties for tissue repair and immunomodulation. The success of MSC therapy in degenerative and/or inflammatory diseases might depend on the robustness of the biological functions of MSCs, which should be linked to their therapeutic potency. Here, we outline the fundamental and advanced concepts of MSC biological features and underline the biological functions of MSCs in their basic and translational aspects in therapy for degenerative and/or inflammatory diseases.

Stem Cell Therapies in Kidney Diseases: Progress and Challenges

The prevalence of renal diseases is emerging as a public health problem. Despite major progress in supportive therapy, mortality rates among patients remain high. In an attempt to find innovative treatments to stimulate kidney regeneration, stem cell-based technology has been proposed as a potentially promising strategy. Here, we summarise the renoprotective potential of pluripotent and adult stem cell therapy in experimental models of acute and chronic kidney injury and we explore the different mechanisms at the basis of stem cell-induced kidney regeneration. Specifically, cell engraftment, incorporation into renal structures, or paracrine activities of embryonic or induced pluripotent stem cells as well as mesenchymal stem cells and renal precursors are analysed. We also discuss the relevance of stem cell secretome-derived bioproducts, including soluble factors and extracellular vesicles, and the option of using them as cell-free therapy to induce reparative processes. The translation of the experimental results into clinical trials is also addressed, highlighting the safety and feasibility of stem cell treatments in patients with kidney injury.

Mesenchymal Stem Cells: a Promising Therapeutic Tool for Acute Kidney Injury

Acute kidney injury (AKI) is a rapid loss of renal function. It has high mortality rates. Still, renal replacement therapy is considered the best solution for recovering AKI. This opens a line of thought to develop an alternative therapy for it without complications. Mesenchymal stem cells are considered a new therapy for treating kidney diseases. The aim of this work was to address the anti-apoptotic, antioxidative, and pro-angiogenic effects of adipose tissue-derived MSCs (AD-MSCs) and bone marrow-MSCs (BM-MSCs) for treating AKI. Adult male Wistar rats were assigned into nine groups (n = 10): (1) the control group; (2) the AKI group, receiving cisplatin; (3) the AKI group treated with AD-MSCs (1 × 10⁶); (4) the AKI group treated with AD-MSCs (2 × 10⁶); (5) the AKI group treated with AD-MSCs (4 × 10⁶); (6) the AKI group treated with losartan; (7) the AKI group treated with BM-MSCs (1 × 10⁶); (8) the AKI group treated with BM-MSCs (2 × 10⁶); and (9) the AKI group treated with BM-MSCs (4 × 10⁶). The results showed a significant rise in creatinine, urea, and cystatin C (cys C) levels and upregulation of p38 mRNA, whereas a significant decline in NAD(P)H quinone oxidoreductase 1 (NQO-1) protein and downregulation of B-cell lymphoma-2 (Bcl-2) mRNA and vascular endothelial growth factor (VEGF) mRNA were recorded in AKI. MSCs could improve renal functions manifested by decreased urea, creatinine, and cys C levels; downregulation of p38; and upregulation of Bcl-2 and VEGF. Moreover, MSC therapy could induce NQO-1 in the treated rats relative to the untreated rats. So, cell-based therapy can reduce AKI through the antioxidative, anti-apoptotic, and pro-angiogenic properties of MSCs. Therefore, the findings received in this attempt create a fertile base for the setup of cell therapy in patients with AKI.

Preconditioning strategies for improving the survival rate and paracrine ability of mesenchymal stem cells in acute kidney injury

Acute kidney injury (AKI) is a common, severe emergency case in clinics, with high incidence, significant mortality and increased costs. Despite development in the understanding of its pathophysiology, the therapeutic choices are still confined to dialysis and renal transplantation. Considering their antiapoptotic, immunomodulatory, antioxidative and pro‐angiogenic effects, mesenchymal stem cells (MSCs) may be a promising candidate for AKI management. Based on these findings, some clinical trials have been performed, but the results are contradictory (NCT00733876, NCT01602328). The low engraftment, poor survival rate, impaired paracrine ability and delayed administration of MSCs are the four main reasons for the limited clinical efficacy. Investigators have developed a series of preconditioning strategies to improve MSC survival rates and paracrine ability. In this review, by summarizing these encouraging studies, we intend to provide a comprehensive understanding of various preconditioning strategies on AKI therapy and improve the prognosis of AKI patients by regenerative medicine.

Tracking of Adipose-Derived Mesenchymal Stromal/Stem Cells in a Model of Cisplatin-Induced Acute Kidney Injury: Comparison of Bioluminescence Imaging versus qRT-PCR

Determining the cell fate and the distribution of mesenchymal stromal/stem cells (MSCs) after transplantation are essential parts of characterizing the mechanisms of action and biosafety profile of stem cell therapy. Many recent studies have shown that MSCs migrate into injured tissues, but are only detectable at extremely low frequencies. We investigated the cell fate of MSCs after transplantation in an acute kidney injury (AKI) mouse model using in vivo bioluminescence imaging (BLI) and subsequent verification of cell migration using quantitative real-time polymerase chain reaction (qRT-PCR). The AKI was induced by a single injection of cisplatin (8 or 12 mg/kg). One day later, adipose-derived mesenchymal stromal/stem cells isolated from luciferase transgenic mice (Luc⁺-mASCs, 5 × 10⁵) were intravenously transplanted. Migration kinetics of the cells was monitored using BLI on day 1, 3, and 6, and finally via quantitative real-time PCR at the endpoint on day 6. Using BLI, infused Luc⁺-mASCs could only be detected in the lungs, but not in the kidneys. In contrast, PCR endpoint analysis revealed that Luc-specific mRNA could be detected in injured renal tissue; compared to the control group, the induction was 2.2-fold higher for the 8 mg/kg cisplatin group (p < 0.05), respectively 6.1-fold for the 12 mg/kg cisplatin group (p < 0.001). In conclusion, our study demonstrated that Luc-based real-time PCR rather than BLI is likely to be a better tool for cell tracking after transplantation in models such as cisplatin-induced AKI.

Bone marrow-mesenchymal stromal cell infusion in patients with chronic kidney disease: A safety study with 18 months of follow-up

BACKGROUND

Chronic kidney disease (CKD) is a progressive loss of kidney function and structure that affects approximately 13% of the population worldwide. A recent meta-analysis revealed that cell-based therapies improve impaired renal function and structure in preclinical models of CKD. We assessed the safety and tolerability of bone marrow-mesenchymal stromal cell (MSC) infusion in patients with CKD.

METHODS

A single-arm study was carried out at one center with 18-month follow-up in seven eligible patients with CKD due to different etiologies such as hypertension, nephrotic syndrome (NS) and unknown etiology. We administered an intravenous infusion (1-2 × 10⁶ cells/kg) of autologous cultured MSCs. The primary endpoint was safety, which was measured by number and severity of adverse events. The secondary endpoint was decrease in the rate of decrease in estimated glomerular filtration rate (eGFR). We compared kidney function during the follow-up visits to baseline and 18 months prior to the intervention.

RESULTS

Follow-up visits of all seven patients were completed; however, we have not observed any cell-related adverse events during the trial. Changes in eGFR (P = 0.10) and serum creatinine (P = 0.24) from 18 months before cell infusion to baseline in comparison with baseline to 18 months were not statistically significant.

CONCLUSIONS

We showed safety and tolerability of a single-dose infusion of autologous MSCs in patients with CKD.

Immunomodulatory effects of mesenchymal stromal cells-derived exosome

The mechanisms underlying immunomodulatory ability of mesenchymal stromal cells (MSCs) remain unknown. Recently, studies suggested that the immunomodulatory activity of MSCs is largely mediated by paracrine factors. Among which, exosome is considered to play a major role in the communication between MSCs and target tissue. The aim of our study is to investigate the effect of MSCs-derived exosome on peripheral blood mononuclear cells (PBMCs), especially T cells. We find that the MSCs-derived exosome extracted from healthy donors' bone marrow suppressed the secretion of pro-inflammatory factor TNF-α and IL-1β, but increased the concentration of anti-inflammatory factor TGF-β during in vitro culture. In addition, exosome may induce conversion of T helper type 1 (Th1) into T helper type 2 (Th2) cells and reduced potential of T cells to differentiate into interleukin 17-producing effector T cells (Th17). Moreover, the level of regulatory T cells (Treg) and cytotoxic T lymphocyte-associated protein 4 were also increased. These results suggested that MSC-derived exosome possesses the immunomodulatory properties. However, it showed no effects on the proliferation of PBMCs or CD3+ T cells, but increases the apoptosis of them. In addition, indoleamine 2, 3-dioxygenase (IDO) was previously shown to mediate the immunoregulation of MSCs, which was increased in PBMCs co-cultured with MSCs. In our study, IDO showed no significant changes in PBMCs exposed to MSCs-derived exosome. We conclude that exosome and MSCs might differ in their immune-modulating activities and mechanisms.

Clinical Translation of Mesenchymal Stromal Cell Therapies in Nephrology

Mesenchymal stromal cells have emerged as potential candidates for cell-based therapies to modulate the immune response in organ transplantation and repair tissues after acute or chronic injury. Preclinical studies have shown convincingly in rodent models that mesenchymal stromal cells can prolong solid organ graft survival and that they can induce immune tolerance, accelerate recovery from AKI, and promote functional improvement in chronic nephropathies. Multiple complex properties of the cells, including immunomodulatory, anti-inflammatory, and proregenerative effects, seem to contribute. The promising preclinical studies have encouraged investigators to explore the safety, tolerability, and efficacy of mesenchymal stromal cell-based therapy in pilot clinical trials, including those for bone marrow and solid organ transplantation, autoimmune diseases, and tissue and organ repair. Here, we review the available data on culture-expanded mesenchymal stromal cells tested in renal transplantation, AKI, and CKD. We also briefly discuss the relevant issues that must be addressed to ensure rigorous assessment of the safety and efficacy of mesenchymal stromal cell therapies to allow the translation of this research into the practice of clinical nephrology.

Effect of adipose-derived mesenchymal stem cell transplantation on vascular calcification in rats with adenine-induced kidney disease

Previous studies have investigated the use of mesenchymal stem cells (MSCs) to treat damaged kidneys. However, the effect of adipose-derived MSCs (ASCs) on vascular calcification in chronic kidney disease (CKD) is still poorly understood. In the present study, we explored the potential of ASCs for the treatment of CKD and vascular calcification. CKD was induced in male Sprague-Dawley rats by feeding them a diet containing 0.75% adenine for 4 weeks. ASCs transplantation significantly reduced serum inorganic phosphorus (Pi) as compared to that in the control. The histopathology of the kidneys showed a greater dilation of tubular lumens and interstitial fibrosis in the control group. Calcium and Pi contents of the aorta in the ASCs transplantation group were lower than those in the control group. Von Kossa staining of the thoracic aorta media revealed that ASCs transplantation suppressed vascular calcification. Thus, this study revealed that autogenic ASCs transplantation inhibits kidney damage and suppresses the progression of vascular calcification in the CKD rat model, suggesting that autogenic ASCs transplantation is a novel approach for preventing the progression of CKD and vascular calcification.

Human mesenchymal stromal cells transplanted into mice stimulate renal tubular cells and enhance mitochondrial function

Mesenchymal stromal cells (MSCs) are renoprotective and drive regeneration following injury, although cellular targets of such an effect are still ill-defined. Here, we show that human umbilical cord (UC)-MSCs transplanted into mice stimulate tubular cells to regain mitochondrial mass and function, associated with enhanced microtubule-rich projections that appear to mediate mitochondrial trafficking to create a reparative dialogue among adjacent tubular cells. Treatment with UC-MSCs in mice with cisplatin-induced acute kidney injury (AKI) regulates mitochondrial biogenesis in proximal tubuli by enhancing PGC1α expression, NAD⁺ biosynthesis and Sirtuin 3 (SIRT3) activity, thus fostering antioxidant defenses and ATP production. The functional role of SIRT3 in tubular recovery is highlighted by data that in SIRT3-deficient mice with AKI, UC-MSC treatment fails to induce renoprotection. These data document a previously unrecognized mechanism through which UC-MSCs facilitate renal repair, so as to induce global metabolic reprogramming of damaged tubular cells to sustain energy supply.

Mesenchymal stromal cells drive renal regeneration following injury. Here, the authors show that human mesenchymal stromal cells, when transplanted into mice with acute kidney injury, stimulate renal tubular cell growth and enhance mitochondrial function via SIRT3.

Umbilical cord extracts improve diabetic abnormalities in bone marrow-derived mesenchymal stem cells and increase their therapeutic effects on diabetic nephropathy

Bone marrow-derived mesenchymal stem cells (BM-MSC) has been applied as the most valuable source of autologous cell transplantation for various diseases including diabetic complications. However, hyperglycemia may cause abnormalities in intrinsic BM-MSC which might lose sufficient therapeutic effects in diabetic patients. We demonstrated the functional abnormalities in BM-MSC derived from both type 1 and type 2 diabetes models in vitro, which resulted in loss of therapeutic effects in vivo in diabetic nephropathy (DN). Then, we developed a novel method to improve abnormalities in BM-MSC using human umbilical cord extracts, namely Wharton’s jelly extract supernatant (WJs). WJs is a cocktail of growth factors, extracellular matrixes and exosomes, which ameliorates proliferative capacity, motility, mitochondrial degeneration, endoplasmic reticular functions and exosome secretions in both type 1 and type 2 diabetes-derived BM-MSC (DM-MSC). Exosomes contained in WJs were a key factor for this activation, which exerted similar effects to complete WJs. DM-MSC activated by WJs ameliorated renal injury in both type 1 and type 2 DN. In this study, we developed a novel activating method using WJs to significantly increase the therapeutic effect of BM-MSC, which may allow effective autologous cell transplantation.

Mesenchymal Stromal Cells Accelerate Epithelial Tight Junction Assembly via the AMP-Activated Protein Kinase Pathway, Independently of Liver Kinase B1

BACKGROUND

Mesenchymal stromal cells (MSC) are fibroblast-like multipotent cells capable of tissue-repair properties. Given the essentiality of tight junctions (TJ) in epithelial integrity, we hypothesized that MSC modulate TJ formation, via the AMP-activated kinase (AMPK) pathway. Liver kinase-β1 (LKB1) and Ca²⁺-calmodulin-dependent protein kinase kinase (CaMKK) represent the main kinases that activate AMPK.

METHODS

The in vitro Ca²⁺ switch from 5 μM to 1.8 mM was performed using epithelial Madin-Darby canine kidney (MDCK) cells cultured alone or cocultured with rat bone marrow-derived MSC or preexposed to MSC-conditioned medium. TJ assembly was measured by assessing ZO-1 relocation to cell-cell contacts. Experiments were conducted using MDCK stably expressing short-hairpin-RNA (shRNA) against LKB1 or luciferase (LUC, as controls). Compound STO-609 (50 μM) was used as CaMKK inhibitor.

RESULTS

Following Ca²⁺ switch, ZO-1 relocation and phosphorylation/activation of AMPK were significantly higher in MDCK/MSC compared to MDCK. No difference in AMPK phosphorylation was observed between LKB1-shRNA and Luc-shRNA MDCK following Ca²⁺ switch. Conversely, incubation with STO-609 prior to Ca²⁺ switch prevented AMPK phosphorylation and ZO-1 relocation. MSC-conditioned medium slightly but significantly increased AMPK activation and accelerated TJ-associated distribution of ZO-1 post Ca²⁺ switch in comparison to regular medium.

CONCLUSIONS

MSC modulate the assembly of epithelial TJ, via the CaMKK/AMPK pathway independently of LKB1.

Immunomodulatory oligonucleotide IMT504: Effects on mesenchymal stem cells as a first-in-class immunoprotective/immunoregenerative therapy

The immune responses of humans and animals to insults (i.e., infections, traumas, tumoral transformation and radiation) are based on an intricate network of cells and chemical messengers. Abnormally high inflammation immediately after insult or abnormally prolonged pro-inflammatory stimuli bringing about chronic inflammation can lead to life-threatening or severely debilitating diseases. Mesenchymal stem cell (MSC) transplant has proved to be an effective therapy in preclinical studies which evaluated a vast diversity of inflammatory conditions. MSCs lead to resolution of inflammation, preparation for regeneration and actual regeneration, and then ultimate return to normal baseline or homeostasis. However, in clinical trials of transplanted MSCs, the expectations of great medical benefit have not yet been fulfilled. As a practical alternative to MSC transplant, a synthetic drug with the capacity to boost endogenous MSC expansion and/or activation may also be effective. Regarding this, IMT504, the prototype of a major class of immunomodulatory oligonucleotides, induces in vivo expansion of MSCs, resulting in a marked improvement in preclinical models of neuropathic pain, osteoporosis, diabetes and sepsis. IMT504 is easily manufactured and has an excellent preclinical safety record. In the small number of patients studied thus far, IMT504 has been well-tolerated, even at very high dosage. Further clinical investigation is necessary to demonstrate the utility of IMT504 for resolution of inflammation and regeneration in a broad array of human diseases that would likely benefit from an immunoprotective/immunoregenerative therapy.

Extracellular Vesicle-Shuttled mRNA in Mesenchymal Stem Cell Communication

Mesenchymal stem cells (MSC) are multipotent cells able to differentiate into several cell types, hence providing cell reservoirs for therapeutic applications. The absence of detectable MSC homing at injury sites suggests that paracrine functions could, at least in part, be mediated by extracellular vesicles (EVs); EVs are newly identified players that are studied mainly as predictive or diagnostic biomarkers. Together with their clinical interests, EVs have recently come to the fore for their role in cell-to-cell communication. In this context, we investigated gene-based communication mechanisms in EVs generated by bone marrow and umbilical cord blood MSC (BMMSC and CBMSC, respectively). Both MSC types released vesicles with similar physical properties, although CBMSC were able to secrete EVs with faster kinetics. A pattern of preferentially incorporated EV transcripts was detected with respect to random internalization from the cytosol, after a validated normalization procedure was established. In the paradigm where EVs act as bioeffectors educating target cells, we demonstrated that kidney tubular cells lacking IL-10 expression and exposed to BMMSC-EVs and CBMSC-EVs acquired the IL-10 mRNA, which was efficiently translated into the corresponding protein. These findings suggest that horizontal mRNA transfer through EVs is a new mechanism in the MSC restoring ability observed in vivo that is here further demonstrated in an in vitro rescue model after acute cisplatin injury of tubular cells. Stem Cells 2017;35:1093-1105.

Embryonic Stem Cells-loaded Gelatin Microcryogels Slow Progression of Chronic Kidney Disease

Background:

Chronic kidney disease (CKD) has become a public health problem. New interventions to slow or prevent disease progression are urgently needed. In this setting, cell therapies associated with regenerative effects are attracting increasing interest. We evaluated the effect of embryonic stem cells (ESCs) on the progression of CKD.

Methods:

Adult male Sprague–Dawley rats were subjected to 5/6 nephrectomy. We used pedicled greater omentum flaps packing ESC-loaded gelatin microcryogels (GMs) on the 5/6 nephrectomized kidney. The viability of ESCs within the GMs was detected using in vitro two-photon fluorescence confocal imaging. Rats were sacrificed after 12 weeks. Renal injury was evaluated using serum creatinine, urea nitrogen, 24 h protein, renal pathology, and tubular injury score results. Structural damage was evaluated by periodic acid-Schiff and Masson trichrome staining.

Results:

In vitro, ESCs could be automatically loaded into the GMs. Uniform cell distribution, good cell attachment, and viability were achieved from day 1 to 7 in vitro. After 12 weeks, in the pedicled greater omentum flaps packing ESC-loaded GMs on 5/6 nephrectomized rats group, the plasma urea nitrogen levels were 26% lower than in the right nephrectomy group, glomerulosclerosis index was 62% lower and tubular injury index was 40% lower than in the 5/6 nephrectomized rats group without GMs.

Conclusions:

In a rat model of established CKD, we demonstrated that the pedicled greater omentum flaps packing ESC-loaded GMs on the 5/6 nephrectomized kidney have a long-lasting therapeutic rescue function, as shown by the decreased progression of CKD and reduced glomerular injury.

Effect of Hypoxia on the Differentiation and the Self-Renewal of Metanephrogenic Mesenchymal Stem Cells

Hypoxia is an important and influential factor in development. The embryonic kidney is exposed to a hypoxic environment throughout its development. The Wnt/β-catenin pathway plays vital roles in the differentiation and self-renewal of metanephrogenic mesenchymal stem cells (MMSCs) from which the kidney is derived. Thus, we hypothesized that hypoxia can regulate the differentiation and pluripotency of MMSCs through the Wnt/β-catenin pathway. To test this hypothesis, MMSCs from rats at embryonic day 18.5 were cultured in normoxic (21% O₂) and hypoxic (1% O₂) conditions. The effects of hypoxia on differentiation, stemness, proliferation, and apoptosis of cultured MMSCs and on the activity of the Wnt/β-catenin pathway were tested. Our results revealed that the hypoxic condition increased the number of epithelial cells (E-cadherin⁺ or CK18⁺) as well the expression of markers of renal tubule epithelia cells (CDH6, Aqp1, and OPN), decreased the number and proliferation of stem cells (SIX-2⁺ or CITED1⁺), and induced apoptosis. Additionally, hypoxia reduced the expression of Wnt4 as well as its downstream molecules β-catenin, LEF-1, and Axin2. Activation of the Wnt/β-catenin pathway by LiCl or BIO modified the effects of hypoxia on the differentiation and self-renewal of MMSCs. Thus, we concluded that hypoxia induces the differentiation and inhibits the self-renewal of MMSCs by inhibiting the Wnt/β-catenin pathway. The observations further our understanding of the effects of hypoxia on kidney.

Mesenchymal stem cell therapy ameliorates diabetic nephropathy via the paracrine effect of renal trophic factors including exosomes

Bone marrow-derived mesenchymal stem cells (MSCs) have contributed to the improvement of diabetic nephropathy (DN); however, the actual mediator of this effect and its role has not been characterized thoroughly. We investigated the effects of MSC therapy on DN, focusing on the paracrine effect of renal trophic factors, including exosomes secreted by MSCs. MSCs and MSC-conditioned medium (MSC-CM) as renal trophic factors were administered in parallel to high-fat diet (HFD)-induced type 2 diabetic mice and streptozotocin (STZ)-induced insulin-deficient diabetic mice. Both therapies showed approximately equivalent curative effects, as each inhibited the exacerbation of albuminuria. They also suppressed the excessive infiltration of BMDCs into the kidney by regulating the expression of the adhesion molecule ICAM-1. Proinflammatory cytokine expression (e.g., TNF-α) and fibrosis in tubular interstitium were inhibited. TGF-β1 expression was down-regulated and tight junction protein expression (e.g., ZO-1) was maintained, which sequentially suppressed the epithelial-to-mesenchymal transition of tubular epithelial cells (TECs). Exosomes purified from MSC-CM exerted an anti-apoptotic effect and protected tight junction structure in TECs. The increase of glomerular mesangium substrate was inhibited in HFD-diabetic mice. MSC therapy is a promising tool to prevent DN via the paracrine effect of renal trophic factors including exosomes due to its multifactorial action.

Novel surgical techniques, regenerative medicine, tissue engineering and innovative immunosuppression in kidney transplantation

On the 60th anniversary of the first successfully performed renal transplantation, we summarize the historical, current and potential future status of kidney transplantation. We discuss three different aspects with a potential significant influence on kidney transplantation progress: the development of surgical techniques, the influence of regenerative medicine and tissue engineering, and changes in immunosuppression. We evaluate the standard open surgical procedures with modern techniques and compare them to less invasive videoscopic as well as robotic techniques. The role of tissue engineering and regenerative medicine as a potential method for future kidney regeneration or replacement and the interesting search for novel solutions in the field of immunosuppression will be discussed. After 60 years since the first successfully performed kidney transplantation, we can conclude that the greatest achievements are associated with the development of surgical techniques and with planned systemic immunosuppression.

Mesenchymal Stem Cell-Based Therapy for Kidney Disease: A Review of Clinical Evidence

Mesenchymal stem cells form a population of self-renewing, multipotent cells that can be isolated from several tissues. Multiple preclinical studies have demonstrated that the administration of exogenous MSC could prevent renal injury and could promote renal recovery through a series of complex mechanisms, in particular via immunomodulation of the immune system and release of paracrine factors and microvesicles. Due to their therapeutic potentials, MSC are being evaluated as a possible player in treatment of human kidney disease, and an increasing number of clinical trials to assess the safety, feasibility, and efficacy of MSC-based therapy in various kidney diseases have been proposed. In the present review, we will summarize the current knowledge on MSC infusion to treat acute kidney injury, chronic kidney disease, diabetic nephropathy, focal segmental glomerulosclerosis, systemic lupus erythematosus, and kidney transplantation. The data obtained from these clinical trials will provide further insight into safety, feasibility, and efficacy of MSC-based therapy in renal pathologies and allow the design of consensus protocol for clinical purpose.

Microvesicles as Vehicles for Tissue Regeneration: Changing of the Guards

PURPOSE OF REVIEW

Microvesicles (MVs) have been recognised as mediators of stem cell function, enabling and guiding their regenerative effects.

RECENT FINDINGS

MVs constitute one unique size class of extracellular vesicles (EVs) directly shed from the cell plasma membrane. They facilitate cell-to-cell communication via intercellular transfer of proteins, mRNA and microRNA (miRNA). MVs derived from stem cells, or stem cell regulatory cell types, have proven roles in tissue regeneration and repair processes. Their role in the maintenance of healthy tissue function throughout the life course and thus in age related health span remains to be elucidated.

SUMMARY

Understanding the biogenesis and mechanisms of action of MVs may enable the development of cell-free therapeutics capable of assisting in tissue maintenance and repair for a variety of age-related degenerative diseases. This review critically evaluates recent work published in this area and highlights important new findings demonstrating the use of MVs in tissue regeneration.

Preserved Nephrogenesis Following Partial Nephrectomy in Early Neonates

Reconstitution of total nephron segments after resection in the adult kidney has not been achieved; however, whether the neonatal kidney can maintain the capacity for neo-nephrogenesis after resection is unknown. We performed partial resection of the kidney in neonatal rats on postnatal days 1 (P1x kidney) and 4 (P4x kidney) and examined morphological changes and relevant factors. The P1x kidney bulged into the newly formed cortex from the wound edge, while nephrogenesis failure was prominent in the P4x kidney. Twenty-eight days post-resection, the glomerular number, cortex area, and collecting duct were preserved in the P1x kidney, whereas these parameters were markedly decreased in the P4x kidney. During normal development, Six2 expression and Six2+ nephron progenitor cells in the cap mesenchyme both rapidly disappear after birth. However, time course analysis for the P1x kidney showed that Six2 expression and Six2+ cells were well preserved in the tissue surrounding the resected area even 2 days after resection. In conclusion, our results indicate that kidneys in early neonate rats retain the capability for neo-nephrogenesis after resection; however, this ability is lost soon after birth, which may be attributed to a declining amount of Six2+ cells.

Human embryonic mesenchymal stem cells participate in differentiation of renal tubular cells in newborn mice

Stem cells are used with increasing success in the treatment of renal tubular injury. However, whether mesenchymal stem cells (MSC) differentiate into renal tubular epithelial cells remains controversial. The aims of the present study were to observe the localization of human embryonic MSCs (hMSCs) in the kidneys of newborn mice, and to investigate hMSC differentiation into tubular epithelium. Primary culture hMSCs were derived from 4–7-week-old embryos and labeled with the cell membrane fluorescent dye PKH-26. The degree of apoptosis, cell growth, differentiation and localization of hMSCs with and without this label were then determined using immunohistochemical methods and flow cytometry. hMSCs and PKH26-labeled hMSCs were revealed to differentiate into chondrocytes and adipocytes, and were demonstrated to have similar proliferative capability. In the two cell types, the antigens CD34 and CD45, indicative of hematopoietic lineages, were not expressed; however, the expression of the mesenchymal markers CD29 and CD90 in MSCs, was significantly increased. During a 4-week culture period, laser confocal microscopy revealed that PKH26-labeled hMSCs in the kidneys of newborn mice gradually dispersed. Two weeks after the injection of the PKH26-labeled cells, the percentage of PKH26-labeled hMSCs localized to the renal tubules was 10±2.1%. In conclusion, PKH26 labeling has no effect on hMSC differentiation, proliferation and mesenchymal cell surface features, and hMSCs injected into the kidneys of newborn mice may transform to renal tubule epithelium.

Renoprotective approaches and strategies in acute kidney injury

Acute kidney injury (AKI) is a major renal disease associated with high mortality rate and increasing prevalence. Decades of research have suggested numerous chemical and biological agents with beneficial effects in AKI. In addition, cell therapy and molecular targeting have been explored for reducing kidney tissue damage and promoting kidney repair or recovery from AKI. Mechanistically, these approaches may mitigate oxidative stress, inflammation, cell death, and mitochondrial and other organellar damage, or activate cytoprotective mechanisms such as autophagy and pro-survival factors. However, none of these findings has been successfully translated into clinical treatment of AKI. In this review, we analyze these findings and propose experimental strategies for the identification of renoprotective agents or methods with clinical potential. Moreover, we propose the consideration of combination therapy by targeting multiple targets in AKI.

Mesenchymal stem cell derived secretome and extracellular vesicles for acute lung injury and other inflammatory lung diseases

INTRODUCTION

Acute respiratory distress syndrome is a major cause of respiratory failure in critically ill patients. Despite extensive research into its pathophysiology, mortality remains high. No effective pharmacotherapy exists. Based largely on numerous preclinical studies, administration of mesenchymal stem or stromal cell (MSC) as a therapeutic for acute lung injury holds great promise, and clinical trials are currently underway. However, concern for the use of stem cells, specifically the risk of iatrogenic tumor formation, remains unresolved. Accumulating evidence now suggest that novel cell-free therapies including MSC-derived conditioned medium and extracellular vesicles released from MSCs might constitute compelling alternatives.

AREAS COVERED

The current review summarizes the preclinical studies testing MSC conditioned medium and/or MSC extracellular vesicles as treatment for acute lung injury and other inflammatory lung diseases.

EXPERT OPINION

While certain logistical obstacles limit the clinical applications of MSC conditioned medium such as the volume required for treatment, the therapeutic application of MSC extracellular vesicles remains promising, primarily due to ability of extracellular vesicles to maintain the functional phenotype of the parent cell. However, utilization of MSC extracellular vesicles will require large-scale production and standardization concerning identification, characterization and quantification.

Special Morphological Features at the Interface of the Renal Stem/Progenitor Cell Niche Force to Reinvestigate Transport of Morphogens During Nephron Induction

Formation of a nephron depends on reciprocal signaling of different morphogens between epithelial and mesenchymal cells within the renal stem/progenitor cell niche. Previously, it has been surmised that a close proximity exists between both involved cell types and that morphogens are transported between them by diffusion. However, actual morphological data illustrate that mesenchymal and epithelial stem/progenitor cell bodies are separated by a striking interface. Special fixation of specimens by glutaraldehyde (GA) solution including cupromeronic blue, ruthenium red, or tannic acid for electron microscopy depicts that the interface is not void but filled in extended areas by textured extracellular matrix. Surprisingly, projections of mesenchymal cells cross the interface to contact epithelial cells. At those sites the plasma membranes of a mesenchymal and an epithelial cell are connected via tunneling nanotubes. Regarding detected morphological features in combination with involved morphogens, their transport cannot longer be explained solely by diffusion. Instead, it has to be sorted according to biophysical properties of morphogens and to detected environment. Thus, the new working hypothesis is that morphogens with good solubility such as glial cell line-derived neurotrophic factor (GDNF) or fibroblast growth factors (FGFs) are transported by diffusion. Morphogens with minor solubility such as bone morphogenetic proteins (BMPs) are secreted and stored for delivery on demand in illustrated extracellular matrix. In contrast, morphogens with poor solubility such as Wnts are transported in mesenchymal cell projections along the plasma membrane or via illustrated tunneling nanotubes. However, the presence of an intercellular route between mesenchymal and epithelial stem/progenitor cells by tunneling nanotubes also makes it possible that all morphogens are transported this way.

Expression of CD24 in Human Bone Marrow-Derived Mesenchymal Stromal Cells Is Regulated by TGFβ3 and Induces a Myofibroblast-Like Genotype

Human bone marrow-derived stromal cells (hBMSCs) derived from the adult organism hold great promise for diverse settings in regenerative medicine. Therefore a more complete understanding of hBMSC biology to fully exploit the cells' potential for clinical settings is important. The protein CD24 has been reported to be involved in a diverse range of processes such as cancer, adaptive immunity, inflammation, and autoimmune diseases in other cell types. Its expression in hBMSCs, which has not yet been analyzed, may add an important aspect in the understanding of hBMSC biology. The present study therefore analyzes the expression, regulation, and functional implication of the surface protein CD24 in hBMSCs. Methods used are stimulation studies with TGF beta as well as shRNA-mediated knockdown and overexpression of CD24 followed by microarray, immunocytochemistry, and flow cytometric analyses. To our knowledge, we demonstrate for the first time that the expression of CD24 is an inherent property of hBMSCs. Importantly, the data links the upregulation of CD24 to the adoption of a myofibroblast-like gene expression pattern in hBMSCs. We demonstrate that CD24 is an important modulator in transforming growth factor beta 3 (TGFβ3) signaling with a reciprocal regulatory relationship between these two proteins.

Icariin protects rats against 5/6 nephrectomy-induced chronic kidney failure by increasing the number of renal stem cells

Background

Chronic kidney disease poses a serious health problem worldwide with increasing prevalence and lack of effective treatment. This study aimed to investigate the mechanism of icariin in alleviating chronic renal failure induced by 5/6 nephrectomy in rats.

Methods

The chronic renal failure model was established by a two-phased 5/6 nephrectomy procedure. The model rats were given daily doses of water or icariin for 8 weeks. The kidney morphology was checked by HE staining. The levels of blood urea nitrogen, serum creatinine, and serum uric acid were measured by colometric methods. The expression of specified genes was analyzed by quantitative real-time PCR and immunohistochemical staining. The number of renal stem/progenitor cells was analyzed by CD133 and CD24 immunohistochemical staining.

Results

Icariin protected against CDK-caused damages to kidney histology and improved renal function, significantly reduced levels of BUN, creatinine, and uric acid. Icariin inhibited the expression level of TGF-β1 whereas upregulated HGF, BMP-7, WT-1, and Pax2 expression. Moreover, ccariin significantly increased the expression of CD24, CD133, Osr1, and Nanog in remnant kidney and the numbers of CD133⁺/CD24⁺ renal stem/progenitor cells.

Conclusions

These data demonstrated that icariin effectively alleviated 5/6 nephrectomy induced chronic renal failure through increasing renal stem/progenitor cells.

Hyperglycemic Stress Impairs the Stemness Capacity of Kidney Stem Cells in Rats

The incidence of acute kidney injury in patients with diabetes is significantly higher than that of patients without diabetes, and may be associated with the poor stemness capacity of kidney stem cells (KSCs) and limited recovery of injured renal tubules. To investigate the effects of hyperglycemic stress on KSC stemness, KSCs were isolated from the rat renal papilla and analyzed for their self-renewal and differentiation abilities. Our results showed that isolated KSCs expressed the mesenchymal stem cell markers N-cadherin, Nestin, CD133, CD29, CD90, and CD73. Moreover, KSCs co-cultured with hypoxia-injured renal tubular epithelial cell (RTECs) induced the expression of the mature epithelial cell marker CK18, suggesting that the KSCs could differentiate into RTECs in vitro. However, KSC proliferation, differentiation ability and tolerance to hypoxia were decreased in high-glucose cultures. Taken together, these results suggest the high-glucose microenvironment can damage the reparative ability of KSCs. It may result in a decreased of recovery capability of renal tubules from injury.