Human heart, spleen, and perirenal fat-derived mesenchymal stem cells have immunomodulatory capacities

The potential mechanisms underlying the modulating effect of perirenal adipose tissue on hypertension: Physical compression, paracrine, and neurogenic regulation

Hypertension, a prevalent global cardiovascular disease, affects approximately 45.4 % of adults worldwide. Despite advances in therapy, hypertension continues to pose a significant health risk due to inadequate management. It has been established that excessive adiposity contributes majorly to hypertension, accounting for 65 to 75 % of primary cases. Fat depots can be categorised into subcutaneous and visceral adipose tissue based on anatomical and physiological characteristics. The metabolic impact and the risk of hypertension are determined more significantly by visceral fat. Perirenal adipose tissue (PRAT), a viscera enveloping the kidney, is known for its superior vascularisation and abundant innervation. Although traditionally deemed as a mechanical support tissue, recent studies have indicated its contributing potential to hypertension. Hypertensive patients tend to have increased PRAT thickness compared to those without, and there is a positive correlation between PRAT thickness and elevated systolic blood pressure. This review encapsulates the anatomical characteristics and biogenesis of PRAT. We provide an overview of the potential mechanisms where PRAT may modulate blood pressure, including physical compression, paracrine effects, and neurogenic regulation. PRAT has become a promising target for hypertension management, and continuous effort is required to further explore the underlying mechanisms.

Hematopoietic cell-based and non-hematopoietic cell-based strategies for immune tolerance induction in living-donor renal transplantation: A systematic review

INTRODUCTION

Despite its use to prevent acute rejection, lifelong immunosuppression can adversely impact long-term patient and graft outcomes. In theory, immunosuppression withdrawal is the ultimate goal of kidney transplantation, and is made possible by the induction of immunological tolerance. The purpose of this paper is to review the safety and efficacy of immune tolerance induction strategies in living-donor kidney transplantation, both chimerism-based and non-chimerism-based. The impact of these strategies on transplant outcomes, including acute rejection, allograft function and survival, cost, and immune monitoring, will also be discussed.

MATERIALS AND METHODS

Databases such as PubMed, Scopus, and Web of Science, as well as additional online resources such as EBSCO, were exhaustively searched. Adult living-donor kidney transplant recipients who developed chimerism-based tolerance after concurrent bone marrow or hematopoietic stem cell transplantation or those who received non-chimerism-based, non-hematopoietic cell therapy using mesenchymal stromal cells, dendritic cells, or regulatory T cells were studied between 2000 and 2021. Individual sources of evidence were evaluated critically, and the strength of evidence and risk of bias for each outcome of the transplant tolerance study were assessed.

RESULTS

From 28,173 citations, 245 studies were retrieved after suitable exclusion and duplicate removal. Of these, 22 studies (2 RCTs, 11 cohort studies, 6 case-control studies, and 3 case reports) explicitly related to both interventions (chimerism- and non-chimerism-based immune tolerance) were used in the final review process and were critically appraised. According to the findings, chimerism-based strategies fostered immunotolerance, allowing for the safe withdrawal of immunosuppressive medications. Cell-based therapy, on the other hand, frequently did not induce tolerance except for minimising immunosuppression. As a result, the rejection rates, renal allograft function, and survival rates could not be directly compared between these two groups. While chimerism-based tolerance protocols posed safety concerns due to myelosuppression, including infections and graft-versus-host disease, cell-based strategies lacked these adverse effects and were largely safe. There was a lack of direct comparisons between HLA-identical and HLA-disparate recipients, and the cost implications were not examined in several of the retrieved studies. Most studies reported successful immunosuppressive weaning lasting at least 3 years (ranging up to 11.4 years in some studies), particularly with chimerism-based therapy, while only a few investigators used immune surveillance techniques. The studies reviewed were often limited by selection, classification, ascertainment, performance, and attrition bias.

CONCLUSIONS

This review demonstrates that chimerism-based hematopoietic strategies induce immune tolerance, and a substantial number of patients are successfully weaned off immunosuppression. Despite the risk of complications associated with myelosuppression. Non-chimerism-based, non-hematopoietic cell protocols, on the other hand, have been proven to facilitate immunosuppression minimization but seldom elicit immunological tolerance. However, the results of this review must be interpreted with caution because of the non-randomised study design, potential confounding, and small sample size of the included studies. Further validation and refinement of tolerogenic protocols in accordance with local practice preferences is also warranted, with an emphasis on patient selection, cost ramifications, and immunological surveillance based on reliable tolerance assays.

Perirenal fat thickness as a superior obesity-related marker of subclinical carotid atherosclerosis in type 2 diabetes mellitus

Objective

Emerging evidence highlighted that perirenal adipose tissue might regulate the cardiovascular and metabolism system through several pathways. This study aimed to assess the association between perirenal fat thickness (PrFT) and subclinical carotid atherosclerosis (SCCA) in type 2 diabetes mellitus (T2DM).

Method

A total of 670 participants with complete data were included in this study. The trained reviewer collected demographic and anthropometric information. Laboratory assessments were determined by standard methods. PrFT and SCCA were evaluated by computed tomography and ultrasound. Binomial logistic regression analysis was conducted to assess the association between PrFT and SCCA. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the identifying value of PrFT for SCCA.

Results

Overall, the prevalence of SCCA was 61.8% in T2DM. PrFT was significantly increased in the SCCA group. Growing trends were observed in the prevalence of hypertension, carotid intima-media thickness (cIMT) > 1, plaque, and SCCA across the PrFT quartiles. Spearman correlation analysis revealed that PrFT was positively associated with cIMT (r = 0.401, p < 0.001). This correlation remained significant after adjustment for visceral fat area (VFA), subcutaneous fat area (SFA), and traditional metabolic risk factors (β = 0.184, p < 0.001). Meanwhile, PrFT was independently correlated with plaque, cIMT > 1 mm, and SCCA. The ORs (95% CI) were 1.072 (1.014-1.135), 1.319 (1.195-1.455), and 1.216 (1.119-1.322). Furthermore, PrFT remained correlated considerably with SCCA in subgroup analysis after stratification for age, sex, smoking, hypertension, and body mass index. From the ROC curve analysis, the AUCs (95% CI) of PrFT, VFA, and SFA identifying SCCA were 0.794 (0.760-0.828), 0.760 (0.724-0.796), and 0.697 (0.656-0.737), respectively. The AUC of PrFT was significantly higher than VFA (p = 0.028) and SFA (p < 0.001). The optimal cutoff values of PrFT were 14.0 mm, with a sensitivity of 66.7% and a specificity of 76.2%.

Conclusion

PrFT was independently associated with cIMT, plaque, cIMT > 1 mm, and SCCA as a superior obesity-related marker of SCCA in T2DM.

Clinical trial registration

Clinical Trials.Gov, identifier ChiCTR2100052032.

Perirenal Fat Thickness is Associated with Metabolic Dysfunction-Associated Fatty Liver Disease in Type 2 Diabetes Mellitus

Objective

Recent advances in perirenal adipose tissue (PAT) highlighted that PAT might involve in the pathogenesis of chronic inflammatory and dysfunctional metabolic diseases. This study assessed the association between perirenal fat thickness (PrFT) and metabolic dysfunction-associated fatty liver disease (MALFD) in type 2 diabetes mellitus (T2DM).

Methods

This study comprised 867 eligible participants with T2DM. Trained reviewers collected anthropometric and biochemical measurements. The diagnosis of MAFLD was based on the latest international expert consensus statement. PrFT and fatty liver were evaluated by computed tomography. The visceral fat area (VFA) and subcutaneous fat area (SFA) were measured by bioelectrical impedance analysis. The non-alcoholic fatty liver disease fibrosis score (NFS) and fibrosis-4 (FIB-4) index were used to assess progressive liver fibrosis in MAFLD.

Results

Overall, the prevalence of MAFLD was 62.3% in T2DM. The PrFT in the MAFLD group was statistically increased than in the non-MAFLD group (P < 0.05). Correlation analysis showed that PrFT was significantly correlated with dysfunctional metabolic factors like body mass index, waist circumference, triglycerides, high-density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, uric acid, and insulin resistance. Multiple regression analysis revealed that PrFT was positively correlated with NFS (β=0.146, P<0.001) and FIB-4 (β=0.082, P=0.025) in the MAFLD. In contrast, PrFT was negatively correlated with CT_L-S (β=-0.188, P<0.001). Furthermore, PrFT was also significantly associated with MAFLD independent of VFA and SFA, the OR (95% CI) was 1.279 (1.191-1.374). Meanwhile, PrFT also had a good identifying value for MAFLD as VFA. The area under the curve (95% CI) value of PrFT identifying MAFLD was 0.782 (0.751-0.812). The optimal cut-off value of PrFT was 12.6mm, with a sensitivity of 77.8% and specificity of 70.8%.

Conclusion

PrFT was independently associated with MAFLD, NFS, and FIB-4 and showed a similar identifying value for MAFLD as VFA, which suggested that PrFT can be used as an alternative index to VFA.

Preliminary Characterization of the Epigenetic Modulation in the Human Mesenchymal Stem Cells during Chondrogenic Process

Regenerative medicine represents a growing hot topic in biomedical sciences, aiming at setting out novel therapeutic strategies to repair or regenerate damaged tissues and organs. For this perspective, human mesenchymal stem cells (hMSCs) play a key role in tissue regeneration, having the potential to differentiate into many cell types, including chondrocytes. Accordingly, in the last few years, researchers have focused on several in vitro strategies to optimize hMSC differentiation protocols, including those relying on epigenetic manipulations that, in turn, lead to the modulation of gene expression patterns. Therefore, in the present study, we investigated the role of the class II histone deacetylase (HDAC) inhibitor, MC1568, in the hMSCs-derived chondrogenesis. The hMSCs we used for this work were the hMSCs obtained from the amniotic fluid, given their greater differentiation capacity. Our preliminary data documented that MC1568 drove both the improvement and acceleration of hMSCs chondrogenic differentiation in vitro, since the differentiation process in MC1568-treated cells took place in about seven days, much less than that normally observed, namely 21 days. Collectively, these preliminary data might shed light on the validity of such a new differentiative protocol, in order to better assess the potential role of the epigenetic modulation in the process of the hypertrophic cartilage formation, which represents the starting point for endochondral ossification.

Evaluation of the Therapeutic Potential of Mesenchymal Stem Cells (MSCs) in Preclinical Models of Autoimmune Diseases

Autoimmune diseases, chronic in nature, are generally hard to alleviate. Present long-term treatments with available drugs such as steroids, immune-suppressive drugs, or antibodies have several debilitating side effects. Therefore, new treatment options are urgently needed. Stem cells, in general, have the potential to reduce immune-mediated damage through immunomodulation and T cell regulation (T regs) by inhibiting the proliferation of dendritic cells and T and B cells and reducing inflammation through the generation of immunosuppressive biomolecules like interleukin 10 (IL-10), transforming growth factor-β (TGF-β), nitric oxide (NO), indoleamine 2,3-dioxygenase (IDO), and prostaglandin E2 (PGE2). Many stem cell-based therapeutics have been evaluated in the clinic, but the overall clinical outcomes in terms of efficacy and the longevity of therapeutic benefits seem to be variable and inconsistent with the postulated benefits. This emphasizes a greater need for building robust preclinical models and models that can better predict the clinical translation of stem cell-based therapeutics. Stem cell therapy based on MSCs having the definitive potential to regulate the immune system and control inflammation is emerging as a promising tool for the treatment of autoimmune disorders while promoting tissue regeneration. MSCs, derived from bone marrow, umbilical cord, and adipose tissue, have been shown to be highly immunomodulatory and anti-inflammatory and shown to enhance tissue repair and regeneration in preclinical models as well as in clinical settings. In this article, a review on the status of MSC-based preclinical disease models with emphasis on understanding disease mechanisms in chronic inflammatory disorders caused by exaggerated host immune response in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) was carried out. We also emphasized various factors that better predict the translation of stem cell therapeutic outcomes from preclinical disease models to human patients.

Human Umbilical Cord Mesenchymal Stem Cells to Treat Neuromyelitis Optica Spectrum Disorder (hUC-MSC-NMOSD): A Study Protocol for a Prospective, Multicenter, Randomized, Placebo-Controlled Clinical Trial

Background

Neuromyelitis Optica spectrum disorder (NMOSD) is severe relapsing and disabling autoimmune disease of the central nervous system. Its optimal first-line treatment to reduce relapse rate and ameliorate neurological disability remains unclear. We will conduct a prospective, multicenter, randomized, placebo-controlled clinical trial to study the safety and effectiveness of human umbilical cord mesenchymal stem cells (hUC-MSCs) in treating NMOSD.

Methods

The trial is planned to recruit 430 AQP4-IgG seropositive NMOSD patients. It consists of three consecutive stages. The first stage will be carried out in the leading center only and aims to evaluate the safety of hUC-MSCs. Patients will be treated with three different doses of hUC-MSCs: 1, 2, or 5 × 10⁶ MSC/kg·weight for the low-, medium-, and high-dose group, respectively. The second and third stages will be carried out in six centers. The second stage aims to find the optimal dosage. Patients will be 1:1:1:1 randomized into the low-, medium-, high-dose group and the controlled group. The third stage aims to evaluate the effectiveness. Patients will be 1:1 randomized into the optimal dose and the controlled group. The primary endpoint is the first recurrent time and secondary endpoints are the recurrent times, EDSS scores, MRI lesion numbers, OSIS scores, Hauser walking index, and SF-36 scores. Endpoint events and side effects will be evaluated every 3 months for 2 years.

Discussion

Although hUC-MSC has shown promising treatment effects of NMOSD in preclinical studies, there is still a lack of well-designed clinical trials to evaluate the safety and effectiveness of hUC-MSC among NMOSD patients. As far as we know, this trial will be the first one to systematically demonstrate the clinical safety and efficacy of hUC-MSC in treating NMOSD and might be able to determine the optimal dose of hUC-MSC for NMOSD patients.

Trial registration

The study was registered with the Chinese Clinical Trial Registry (CHICTR.org.cn) on 2 March 2016 (registration No. ChiCTR-INR-16008037), and the revised trial protocol (Protocol version 1.2.1) was released on 16 March 2020.

Optimization of adipose tissue-derived mesenchymal stromal cells transplantation for bone marrow repopulation following irradiation

BACKGROUND

Bone marrow (BM) suppression is one of the most common side effects of radiotherapy and the primary cause of death following exposure to irradiation. Despite concerted efforts, there is no definitive treatment method available. Recent studies have reported using mesenchymal stromal cells (MSCs), but their therapeutic effects are contested.

AIM

We administered and examined the effects of various amounts of adipose-derived MSCs (ADSCs) in mice with radiation-induced BM suppression.

METHODS

Mice were divided into three groups: Normal control group, irradiated (RT) group, and stem cell-treated group following whole-body irradiation (WBI). Mouse ADSCs (mADSCs) were transplanted into the peritoneal cavity either once or three times at 5 × 10⁵ cells/200 μL. The white blood cell count and the levels of, plasma cytokines, BM mRNA, and BM surface markers were compared between the three groups. Human BM-derived CD34⁺ hematopoietic progenitor cells were co-cultured with human ADSCs (hADSCs) or incubated in the presence of hADSCs conditioned media to investigate the effect on human cells in vitro.

RESULTS

The survival rate of mice that received one transplant of mADSCs was higher than that of mice that received three transplants. Multiple transplantations of ADSCs delayed the repopulation of BM hematopoietic stem cells. Anti-inflammatory effects and M2 polarization by intraperitoneal ADSCs might suppress erythropoiesis and induce myelopoiesis in sub-lethally RT mice.

CONCLUSION

The results suggested that an optimal amount of MSCs could improve survival rates post-WBI.

Characterization and differentiation potential of mesenchymal stem cells isolated from multiple canine adipose tissue sources

Background

Mesenchymal stem cells (MSCs) are undifferentiated cells that can give rise to a mesoderm lineage. Adipose-derived MSCs are an easy and accessible source for MSCs isolation, although each source of MSC has its own advantages and disadvantages. Our study identifies a promising source for the isolation and differentiation of canines MSCs. For this purpose, adipose tissue from inguinal subcutaneous (SC), perirenal (PR), omental (OM), and infrapatellar fat pad (IPFP) was isolated and processed for MSCs isolation. In the third passage, MSCs proliferation/metabolism, surface markers expression, in vitro differentiation potential and quantitative reverse transcription PCR (CD73, CD90, CD105, PPARγ, FabP4, FAS, SP7, Osteopontin, and Osteocalcin) were evaluated.

Results

Our results showed that MSCs derived from IPFP have a higher proliferation rate, while OM-derived MSCs have higher cell metabolism. In addition, MSCs from all adipose tissue sources showed positive expression of CD73 (NT5E), CD90 (THY1), CD105 (ENDOGLIN), and very low expression of CD45. The isolated canine MSCs were successfully differentiated into adipogenic and osteogenic lineages. The oil-red-O quantification and adipogenic gene expression (FAS, FabP4, and PPARγ) were higher in OM-derived cells, followed by IPFP-MSCs. Similarly, in osteogenic differentiation, alkaline phosphatase activity and osteogenic gene (SP7 and Osteocalcin) expression were higher in OM-derived MSCs, while osteopontin expression was higher in PR-derived MSCs.

Conclusion

In summary, among all four adipose tissue sources, OM-derived MSCs have better differentiation potential toward adipo- and osteogenic lineages, followed by IPFP-MSCs. Interestingly, among all adipose tissue sources, MSCs derived from IPFP have the maximum proliferation potential. The characterization and differentiation potential of canine MSCs isolated from four different adipose tissue sources are useful to assess their potential for application in regenerative medicine.

Surface stiffness depended gingival mesenchymal stem cell sensitivity to oxidative stress

Mesenchymal stem cells (MSCs) are widely used in the fields of cell therapy and tissue engineering, due to their wide spectrum of differentiation potential, immunomodulation function and ongoing oxidative stress (OS) reduction. Nevertheless, OS impact is often overlooked in these research fields. It is not only responsible for the induction and development of many ailments, e.g., diabetes, lung fibrosis, and cancer, moreover, OS causes stem cell death and senescence during cell therapy and tissue engineering practices. As MSCs are used to treat various tissues, they interact with different tissue-specific mechanical environments, thus it is important to understand how the mechanical environment impacts MSC sensitivity to OS. In this work, for the first time, as known to the authors, it was shown that gingival MSCs (GMSCs) sensitivity to OS depends on the stiffness of the surface, on which the cells are grown. Furthermore, the activity and expression of mitogen activated protein kinases ERK, JNK, and p38 were surface stiffness dependent. GMSCs isolated from intermediate/stiff gingiva tissue (~20 kPa) have shown the best proliferative and survival properties, then grown on the stiffest tissues mimicking polyacrylamide hydrogels (40 kPa). Therefore, MSC source might determine their sensitivity to OS in different stiffness environments and should be accounted when developing a treatment strategy.

Safety and therapeutic potential of human bone marrow-derived mesenchymal stromal cells in regenerative medicine

Regenerative medicine is considered as an alternative approach to healthcare. Owing to their pluripotent abilities and their relative lack of ethical and legal issues, adult stem cells are considered as optimal candidates for use in the treatment of various diseases. Bone marrow-derived mesenchymal stem cells are among the most promising candidates for clinical applications as they have expressed a higher degree of plasticity in vitro. Many investigators have begun to examine how bone marrow stem cells might be used to rebuild damaged tissues. The systemic administration of cells for therapeutic applications requires efficient migration and homing of cells to the target site. Cell adhesion molecules and their ligands, chemokines, extracellular matrix components and specialized bone marrow niches all participate in the proper regulation of this process. MSCs suppress the pathophysiological process that is mediated by chronic inflammation and contributes to a modification of the microenvironment and tissue regeneration. Due to the intricacy of the mesenchymal stem cell, there is ever-increasing amount of data emerging about their migration and regenerative mechanisms. Many factors influence MSC mobilization and their homing to injured tissues. This review summarizes the current clinical and pre-clinical data available in literature regarding the use of MSC in tissue repair and their prospective therapeutic role in various diseases and the underlying repair mechanisms will be discussed.

Mesenchymal stem cells enhance the impact of KIR receptor-ligand mismatching on acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation in patients with acute myeloid leukemia but not in those with acute lymphocytic leukemia

Killer cell immunoglobulin-like receptor (KIR) receptor-ligand mismatch has been shown to be protective for acute and chronic graft-versus-host disease (aGVHD, cGVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute leukemia. Mesenchymal stem cells (MSC) have been considered as one of the most promising prophylaxis for severe GVHD. However, there are no prospective or retrospective studies determining whether they can work synergistically on GVHD. To investigate the potential influence of KIR matching and MSCs, and their synergism on aGVHD and cGVHD after allo-HSCT in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) patients. Data from 104 patients with AML and 50 patients with ALL treated with allo-HSCT in the transplantation unit were retrospectively analyzed. KIR genotyping was performed by the PCR-SSO method. The amplicons were quantified on the Luminex 200 flow analyzer and analyzed using the Quick-Type for Lifecodes software to generate KIR data. Cox proportional hazards models were used in multivariate analyses. KIR receptor-ligand matching was associated with an increased risk of grade II-IV aGVHD compared to KIR receptor-ligand mismatching (p < 0.001) in AML patients, but KIR ligand-mismatching had no significant effect on aGVHD or cGVHD in ALL patients. In contrast, MSCs reduced the incidence of grade II-IV aGVHD in both AML and ALL patients (AML: p = 0.006; ALL: p = 0.008) regardless of KIR mismatching. The combination of KIR receptor-ligand mismatch and MSC transplantation significantly suppressed grade II-IV aGVHD occurrence in AML patients (p = 0.039). In the KIR mismatch group, the incidence of aGVHD was 2.8% in patients receiving MSC compared to 14.6% in those who did not (p = 0.047). KIR receptor-ligand mismatch, MSC transplantation and their combined use significantly reduced the risk of aGVHD after allo-HSCT. These data provide a clinically applicable strategy to reduce aGVHD, thus improving allo-HSCT outcome.

Harnessing adipose stem cell diversity in regenerative medicine

Since the first isolation of mesenchymal stem cells from lipoaspirate in the early 2000s, adipose tissue has been a darling of regenerative medicine. It is abundant, easy to access, and contains high concentrations of stem cells (ADSCs) exhibiting multipotency, proregenerative paracrine signaling, and immunomodulation—a winning combination for stem cell-based therapeutics. While basic science, preclinical and clinical findings back up the translational potential of ADSCs, the vast majority of these used cells from a single location—subcutaneous abdominal fat. New data highlight incredible diversity in the adipose morphology and function in different anatomical locations or depots. Even in isolation, ADSCs retain a memory of this diversity, suggesting that the optimal adipose source material for ADSC isolation may be application specific. This review discusses our current understanding of the heterogeneity in the adipose organ, how that heterogeneity translates into depot-specific ADSC characteristics, and how atypical ADSC populations might be harnessed for regenerative medicine applications. While our understanding of the breadth of ADSC heterogeneity is still in its infancy, clear trends are emerging for application-specific sourcing to improve regenerative outcomes.

Topical cell-free conditioned media harvested from adipose tissue-derived stem cells promote recovery from corneal epithelial defects caused by chemical burns

Corneal chemical burns can lead to blindness following serious complications. As most of these complications are caused by failure of reepithelization during the acute phase, treatment at this stage is critical. Although there have been some studies on corneal injury recovery using adipose tissue-derived stem cells (ADSCs), none has reported the effect of topical cell-free conditioned culture media (CM) derived from ADSCs on corneal epithelial regeneration. Here, the best conditions for CM were selected and used for in vitro and in vivo experiments. Corneal burn in rats was induced using 100% alcohol. The chosen CM was administered to corneal burn rats (CM-treated [CT] group) four times a day for three days and this group was compared with the normal control and corneal burn (CB) groups. Biomicroscopic fluorescence images and the actual physical corneas were taken over time and used for analysis. mRNA levels of hepatocyte growth factor and epidermal growth factor (EGF) were significantly increased, whereas those of vascular endothelial growth factor, interleukin (IL)-1β, IL-6, IL-10, and matrix metalloproteinase-9 were significantly decreased in the CT group compared with those in the CB group. The numbers of proliferating cell nuclear antigen- and zonular occludens-1-positive cells in the CT group were significantly higher than those in the CB group. The macrophage-infiltrating corneas in the CT group expressed significantly more of the M2 marker arginase than corneas in the CB group. Optimal CM (× 0.5 concentration) treatment significantly accelerated the migration of corneal epithelial cells and induced upregulation of the expression of IL-6, EGF, and C-X-C chemokine receptor type 4 mRNAs. Overall, in this study, topical administration of cell-free CM promoted regeneration of the corneal epithelium after induction of chemical burns.

Evaluation of Porcine Versus Human Mesenchymal Stromal Cells From Three Distinct Donor Locations for Cytotherapy

Background: Mesenchymal stromal cell (MSC)-based cytotherapies fuel the hope for reduction of chronic systemic immunosuppression in allotransplantation, and our group has previously shown this capability for both swine and human cells. MSCs harvested from distinct anatomical locations may have different behavior and lead to different outcomes in both preclinical research and human trials. To provide an effective reference for cell therapy studies, we compared human and porcine MSCs from omental fat (O-ASC), subcutaneous fat (SC-ASC) and bone marrow (BM-MSC) under rapid culture expansion with endothelial growth medium (EGM).

Methods: MSCs isolated from pigs and deceased human organ donors were compared for yield, viability, cell size, population doubling times (PDT), surface marker expression and differentiation potential after rapid expansion with EGM. Immunosuppressant toxicity on MSCs was investigated in vitro for four different standard immunosuppressive drugs. Immunomodulatory function was compared in mixed lymphocyte reaction assays (MLR) with/without immunosuppressive drug influence.

Results: Human and porcine omental fat yielded significantly higher cell numbers than subcutaneous fat. Initial PDT was significantly shorter in ASCs than BM-MSCs and similar thereafter. Viability was reduced in BM-MSCs. Porcine MSCs were positive for CD29, CD44, CD90, while human MSCs expressed CD73, CD90 and CD105. All demonstrated confirmed adipogenic differentiation capacity. Cell sizes were comparable between groups and were slightly larger in human cells. Rapamycin revealed slight, mycophenolic acid strong and significant dose-dependent toxicity on viability/proliferation of almost all MSCs at therapeutic concentrations. No relevant toxicity was found for Tacrolimus and Cyclosporin A. Immunomodulatory function was dose-dependent and similar between groups. Immunosuppressants had no significant adverse effect on MSC immunomodulatory function.

Discussion: MSCs from different harvest locations and donor species differ in terms of isolation yields, viability, PDT, and size. We did not detect relevant differences in immunomodulatory function with or without the presence of immunosuppressants. Human and pig O-ASC, SC-ASC and BM-MSC share similar immunomodulatory function in vitro and warrant confirmation in large animal studies. These findings should be considered in preclinical and clinical MSC applications.

Associations of Perirenal Fat Thickness with Renal and Systemic Calcified Atherosclerosis

BACKGROUND

We investigated associations between perirenal fat thickness and atherosclerotic calcification in six different vascular beds.

METHODS

Using a community-based cohort (n=3,919), perirenal fat thickness was estimated from computed tomography scans. It was classified as Q1 (the lowest quartile) to Q4 (the highest quartile) in each sex. Calcification in the carotid arteries, coronary arteries, thoracic aorta, abdominal aorta, iliac arteries, and renal arteries was evaluated.

RESULTS

Perirenal fat thickness was associated with older age (P<0.01) and a higher prevalence of obesity, hypertension, and dyslipidemia (P<0.01 for all). Perirenal fat thickness was independently associated with renal arterial calcification even after adjustment for age, sex, body mass index, hypertension, dyslipidemia, smoking history, and family history of heart diseases in first-degree relatives (odds ratio [OR] per quartile of perirenal fat thickness, 1.25; 95% confidence interval [CI], 1.09 to 1.44). Compared to Q1, the odds of renal arterial calcification in Q4 was about two times higher (OR, 2.05; 95% CI, 1.29 to 3.25). After adjustment for renal arterial calcification and atherosclerotic risk factors, the only other vascular bed where perirenal fat thickness showed a significant association with calcification was the abdominal aorta (OR, 1.11; 95% CI, 1.00 to 1.23; P=0.045).

CONCLUSION

Perirenal fat thickness was independently associated with vascular calcification in the renal artery and abdominal aorta.

Hypoxic Preconditioning Enhances Survival and Proangiogenic Capacity of Human First Trimester Chorionic Villus-Derived Mesenchymal Stem Cells for Fetal Tissue Engineering

Prenatal stem cell-based regenerative therapies have progressed substantially and have been demonstrated as effective treatment options for fetal diseases that were previously deemed untreatable. Due to immunoregulatory properties, self-renewal capacity, and multilineage potential, autologous human placental chorionic villus-derived mesenchymal stromal cells (CV-MSCs) are an attractive cell source for fetal regenerative therapies. However, as a general issue for MSC transplantation, the poor survival and engraftment is a major challenge of the application of MSCs. Particularly for the fetal transplantation of CV-MSCs in the naturally hypoxic fetal environment, improving the survival and engraftment of CV-MSCs is critically important. Hypoxic preconditioning (HP) is an effective priming approach to protect stem cells from ischemic damage. In this study, we developed an optimal HP protocol to enhance the survival and proangiogenic capacity of CV-MSCs for improving clinical outcomes in fetal applications. Total cell number, DNA quantification, nuclear area test, and cell viability test showed HP significantly protected CV-MSCs from ischemic damage. Flow cytometry analysis confirmed HP did not alter the immunophenotype of CV-MSCs. Caspase-3, MTS, and Western blot analysis showed HP significantly reduced the apoptosis of CV-MSCs under ischemic stimulus via the activation of the AKT signaling pathway that was related to cell survival. ELISA results showed HP significantly enhanced the secretion of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) by CV-MSCs under an ischemic stimulus. We also found that the environmental nutrition level was critical for the release of brain-derived neurotrophic factor (BDNF). The angiogenesis assay results showed HP-primed CV-MSCs could significantly enhance endothelial cell (EC) proliferation, migration, and tube formation. Consequently, HP is a promising strategy to increase the tolerance of CV-MSCs to ischemia and improve their therapeutic efficacy in fetal clinical applications.

Isolation, Characterization, Differentiation and Immunomodulatory Capacity of Mesenchymal Stromal/Stem Cells from Human Perirenal Adipose Tissue

Mesenchymal stromal/stem cells (MSCs) are immature multipotent cells, which represent a rare population in the perivascular niche within nearly all tissues. The most abundant source to isolate MSCs is adipose tissue. Currently, perirenal adipose tissue is rarely described as the source of MSCs. MSCs were isolated from perirenal adipose tissue (prASCs) from patients undergoing tumor nephrectomies, cultured and characterized by flow cytometry and their differentiation potential into adipocytes, chondrocytes, osteoblasts and epithelial cells. Furthermore, prASCs were stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA) or a mixture of cytokines (cytomix). In addition, prASC susceptibility to human cytomegalovirus (HCMV) was investigated. The expression of inflammatory readouts was estimated by qPCR and immunoassay. HCMV infection was analyzed by qPCR and immunostaining. Characterization of cultured prASCs shows the cells meet the criteria of MSCs and prASCs can undergo trilineage differentiation. Cultured prASCs can be induced to differentiate into epithelial cells, shown by cytokeratin 18 expression. Stimulation of prASCs with LPS or cytomix suggests the cells are capable of initiating an inflammation-like response upon stimulation with LPS or cytokines, whereas, LTA did not induce a significant effect on the readouts (ICAM-1, IL-6, TNFα, MCP-1 mRNA and IL-6 protein). HCMV broadly infects prASCs, showing a viral load dependent cytopathological effect (CPE). Our current study summarizes the isolation and culture of prASCs, clearly characterizes the cells, and demonstrates their immunomodulatory potential and high permissiveness for HCMV.

Mesenchymal Stromal Cells Anno 2019: Dawn of the Therapeutic Era? Concise Review

2018 was the year of the first marketing authorization of an allogeneic stem cell therapy by the European Medicines Agency. The authorization concerns the use of allogeneic adipose tissue-derived mesenchymal stromal cells (MSCs) for treatment of complex perianal fistulas in Crohn's disease. This is a breakthrough in the field of MSC therapy. The last few years have, furthermore, seen some breakthroughs in the investigations into the mechanisms of action of MSC therapy. Although the therapeutic effects of MSCs have largely been attributed to their secretion of immunomodulatory and regenerative factors, it has now become clear that some of the effects are mediated through host phagocytic cells that clear administered MSCs and in the process adapt an immunoregulatory and regeneration supporting function. The increased interest in therapeutic use of MSCs and the ongoing elucidation of the mechanisms of action of MSCs are promising indicators that 2019 may be the dawn of the therapeutic era of MSCs and that there will be revived interest in research to more efficient, practical, and sustainable MSC-based therapies. Stem Cells Translational Medicine 2019;8:1126-1134.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Mesenchymal stem cells overexpressing hepatocyte nuclear factor-4 alpha alleviate liver injury by modulating anti-inflammatory functions in mice

Background

Mesenchymal stem cells (MSCs) can migrate to tissue injury sites where they can induce multipotential differentiation and anti-inflammation effects to treat tissue injury. When traditional therapeutic methods do not work, MSCs are considered to be one of the best candidates for cell therapy. MSCs have been used for treating several injury- and inflammation-associated diseases, including liver cirrhosis. However, the therapeutic effect of MSCs is limited. In some cases, the anti-inflammatory function of naïve MSCs is not enough to rescue tissue injury.

Methods

Carbon tetrachloride (CCl₄) was used to establish a mouse liver cirrhosis model. Enhanced green fluorescence protein (EGFP) and hepatocyte nuclear factor-4α (HNF-4α) overexpression adenoviruses were used to modify MSCs. Three weeks after liver injury induction, mice were injected with bone marrow MSCs via their tail vein. The mice were then sacrificed 3 weeks after MSC injection. Liver injury was evaluated by measuring glutamic-pyruvic transaminase (ALT) and glutamic oxalacetic transaminase (AST) levels. Histological and molecular evaluations were performed to study the mechanisms.

Results

We found that HNF-4α-overexpressing MSCs had a better treatment effect than unmodified MSCs on liver cirrhosis. In the CCl₄-induced mouse liver injury model, we found that HNF-4α-MSCs reduced inflammation in the liver and alleviated liver injury. In addition, we found that HNF-4α promoted the anti-inflammatory effect of MSCs by enhancing nitric oxide synthase (iNOS) expression, which was dependent on the nuclear factor kappa B (NF-κB) signalling pathway.

Conclusions

MSCs overexpressing HNF-4α exerted good therapeutic effects against mouse liver cirrhosis due to an enhanced anti-inflammatory effect. Gene modification is likely a promising method for improving the effects of cell therapy.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1260-7) contains supplementary material, which is available to authorized users.

Effects of Normothermic Machine Perfusion Conditions on Mesenchymal Stromal Cells

Ex-situ normothermic machine perfusion (NMP) of transplant kidneys allows assessment of kidney quality and targeted intervention to initiate repair processes prior to transplantation. Mesenchymal stromal cells (MSC) have been shown to possess the capacity to stimulate kidney repair. Therefore, the combination of NMP and MSC therapy offers potential to repair transplant kidneys. It is however unknown how NMP conditions affect MSC. In this study the effect of NMP perfusion fluid on survival, metabolism and function of thawed cryopreserved human (h)MSC and porcine (p)MSC in suspension conditions was studied. Suspension conditions reduced the viability of pMSC by 40% in both perfusion fluid and culture medium. Viability of hMSC was reduced by suspension conditions by 15% in perfusion fluid, whilst no differences were found in survival in culture medium. Under adherent conditions, survival of the cells was not affected by perfusion fluid. The perfusion fluid did not affect survival of fresh MSC in suspension compared to the control culture medium. The freeze-thawing process impaired the survival of hMSC; 95% survival of fresh hMSC compared to 70% survival of thawed hMSC. Moreover, thawed MSC showed increased levels of reactive oxygen species, which indicates elevated levels of oxidative stress, and reduced mitochondrial activity, which implies reduced metabolism. The adherence of pMSC and hMSC to endothelial cells was reduced after the thawing process, effect which was particularly profound in in the perfusion fluid. To summarize, we observed that conditions required for machine perfusion are influencing the behavior of MSC. The freeze-thawing process reduces survival and metabolism and increases oxidative stress, and diminishes their ability to adhere to endothelial cells. In addition, we found that hMSC and pMSC behaved differently, which has to be taken into consideration when translating results from animal experiments to clinical studies.

Perirenal Fat: A Unique Fat Pad and Potential Target for Cardiovascular Disease

Although visceral obesity is recognized as a risk factor for cardiovascular diseases (CVDs), the efficacy of omental fat removal in CVD treatment is still controversial. There is a need to identify other visceral fat depots for CVD management. This review aims to provide a summary on perirenal fat as an important risk factor for CVD. Studies on epidemiology, anatomy, and function of perirenal fat were reviewed. Observational studies in humans suggest that excessive perirenal fat increases the risk of hypertension and coronary heart disease. Anatomy studies prove that perirenal fat is unique compared to other connective tissues in that it is well vascularized, innervated, and drains into the lymphatic system. Other special morphological features include a complete fascia border, sympathetic-independent development of architecture, and proximity to the kidneys. Based on these anatomical features, perirenal fat regulates the cardiovascular system presumably via neural reflex, adipokine secretion, and fat-kidney interaction. These new insights suggest that perirenal fat may constitute a promising target for CVD management.

Fibroblasts as a practical alternative to mesenchymal stem cells

Mesenchymal stem cell (MSC) therapy offers great potential for treatment of disease through the multifunctional and responsive ability of these cells. In numerous contexts, MSC have been shown to reduce inflammation, modulate immune responses, and provide trophic factor support for regeneration. While the most commonly used MSC source, the bone marrow provides relatively little starting material for cellular expansion, and requires invasive extraction means, fibroblasts are easily harvested in large numbers from various biological wastes. Additionally, in vitro expansion of fibroblasts is significantly easier given the robustness of these cells in tissue culture and shorter doubling time compared to typical MSC. In this paper we put forward the concept that in some cases, fibroblasts may be utilized as a more practical, and potentially more effective cell therapy than mesenchymal stem cells. Anti-inflammatory, immune modulatory, and regenerative properties of fibroblasts will be discussed in the context of regenerative medicine.

Enhancement of Immunoregulatory Function of Modified Bone Marrow Mesenchymal Stem Cells by Targeting SOCS1

Objective

The study aim to investigate the role of microRNA-155 (miR-155) on the immunoregulatory function of bone marrow mesenchymal stem cells (MSCs).

Methods

MSCs were isolated from 2-week-old Sprague-Dawley rats and identified by flow cytometry using anti-CD29, anti-CD44, anti-CD34, and anti-CD45 antibodies. MSCs were transfected with miR155-mimics, miR155-inhibitor, and control oligos, respectively, and then cocultured with spleen mononuclear cells (SMCs). The mRNA levels of Th1, Th2, Th17, and Treg cell-specific transcription factors (Tbx21, Gata3, Rorc, and Foxp3, resp.) and the miR-155 target gene SOCS1 were detected by quantitative real-time PCR (qPCR) in SMCs. The proportion of CD4⁺ FOXP3⁺ Treg cells was detected by flow cytometry. In addition, the effects of MSCs transfected with miR-155 on the migration of rat SMCs were investigated by transwell chamber.

Results

CD29 and CD44 were expressed in MSCs, while CD34 and CD45 were negative. The percentage of CD4⁺ FOXP3⁺ Treg cells in the SMC population was significantly higher compared with that noted in SMCs control group (p < 0.001) following 72 hours of coculture with miR155-mimics-transfected SMCs. In contrast, the percentage of CD4⁺ FOXP3⁺ Treg cells in the SMCs cocultured with miR155-inhibitor-transfected MSCs was significantly lower compared with that noted in SMCs control group (p < 0.001). MiR155-mimics-transfected MSCs inhibited the expression of Tbx21, Rorc, and SOCS1, while the expression of Gata3 and Foxp3 was increased. In contrast to the downregulation of the aforementioned genes, miR155-inhibitor-transfected MSCs resulted in upregulation of Tbx21, Rorc, and SOCS1 expression levels and inhibition of Gata3 and Foxp3. In the transwell assay, miR155-mimics-transfected MSCs exhibited lower levels of SMCs migration, while the miR155-inhibitor-transfected MSCs demonstrated significantly higher levels of migration, compared with the blank control group (p < 0.01, resp.).

Conclusion

miR-155 favors the differentiation of T cells into Th2 and Treg cells in MSCs, while it inhibits the differentiation to Th1 and Th17 cells.

Clinical feasibility of umbilical cord tissue-derived mesenchymal stem cells in the treatment of multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a progressively debilitating neurological condition in which the immune system abnormally erodes the myelin sheath insulating the nerves. Mesenchymal stem cells (MSC) have been used in the last decade to safely treat certain immune and inflammatory conditions.

METHODS

A safety and feasibility study was completed on the use of umbilical cord MSC (UCMSC) as a treatment for MS. In this 1-year study, consenting subjects received seven intravenous infusions of 20 × 10⁶ UCMSC over 7 days. Efficacy was assessed at baseline, 1 month and 1 year after treatment, including magnetic resonance imaging (MRI) scans, Kurtzke Expanded Disability Status Scale (EDSS), Scripps Neurological Rating Scale, Nine-Hole Peg Test, 25-Foot Walk Test, and RAND Short Form-36 quality of life questionnaire.

RESULTS

Twenty subjects were enrolled in this study. No serious adverse events were reported. Of the mild AEs denoted as possibly related to treatment, most were headache or fatigue. Symptom improvements were most notable 1 month after treatment. Improvements were seen in EDSS scores (p < 0.03), as well as in bladder, bowel, and sexual dysfunction (p < 0.01), in non-dominant hand average scores (p < 0.01), in walk times (p < 0.02) and general perspective of a positive health change and improved quality of life. MRI scans of the brain and the cervical spinal cord showed inactive lesions in 15/18 (83.3%) subjects after 1 year.

CONCLUSIONS

Treatment with UCMSC intravenous infusions for subjects with MS is safe, and potential therapeutic benefits should be further investigated. Trial registration ClinicalTrials.gov NCT02034188. Registered Jan 13, 2014. https://clinicaltrials.gov/ct2/show/NCT02034188.

Isolation and characterization of mesenchymal stem cells from human fetus heart

Background

Mesenchymal stem cells (MSCs) are promising cells for cardiovascular regenerative medicine. However, their potential may be limited, because of their restricted cardiovascular differentiation potential and decline in their number and functional characteristics with increasing donor age. We have previously shown that rat fetus heart harbors primitive MSCs and administration of these cells improved left ventricular (LV) function after ischemia/reperfusion injury in rats. To evaluate their potential as a new cell type for clinical cardiovascular cell therapy, we have undertaken this study on the isolation and characterization of human fetal cardiac MSCs (hfC-MSCs).

Methods

MSCs were isolated from the heart of five 14-16-week-old aborted human fetuses and studied for their growth characteristics, karyotypic stability and senescence over successive passages, expression of mesenchymal and embryonal markers by flow cytometry and immunocytochemistry, constitutive expression of cardiovascular genes by RT-PCR, differentiation into cells of the cardiovascular lineage and their immunomodulatory properties.

Results

The hfC-MSCs grew as adherent monolayer with spindle shaped morphology and exhibited rapid proliferation with an average population doubling time of 34 hours and expansion to up to more than 80 population doublings with maintenance of a normal karyotype and without senescence. Immunophenotyping showed that they had similar phenotype as human bone marrow mesenchymal stem cells (hBM-MSCs) expressing CD73, CD90, CD105 and lacking expression of CD31, CD34, CD45, HLA-DR. However, hfC-MSCs expressed significantly higher levels of CD117 and SSEA-4 compared to hBM-MSCs. In addition, hfC-MSCs expressed the embryonal markers Oct-4, Nanog and Sox-2 as compared to hBM-MSCs. Further, hfC-MSCs had significantly higher expression of the cardiovascular genes viz. ISL-1, flk-1, GATA-4, NKX2.5 and MDR-1 as compared to hBM-MSCs, and could be differentiated into major cardiovascular cells (cardiomyocytes, endothelial cells, smooth muscle cells). Interestingly, hfC-MSCs markedly reduced T-lymphocyte proliferation with an increased secretion of TGF-β and IL-10.

Conclusions

Our results show that human fetus heart is a novel source of primitive MSCs with cardiovascular commitment which may have a potential therapeutic application in cardiovascular regenerative medicine.

Comparable osteogenic capacity of mesenchymal stem or stromal cells derived from human amnion membrane and bone marrow

So far, substantial attentions have been attracted to the application of mesenchymal stem or stromal cells (MSCs) in different therapeutic approaches. Although human bone marrow is commonly considered as a major source for MSCs, having an invasive collection method, ethical consideration and donor availability create a challenge for scientists, leading them to explore better alternative sources for MSCs. The study presented here aimed to characterize and compare osteogenic capacity of MSCs obtained from the amnion membrane (AM) with those originated from BM. Cells isolated from AMs and BMs were cultured in DMEM-low glucose supplemented with FBS, penicillin and streptomycin. After 24 h of incubation, cells adhered to the plastic surface of the flasks were allowed to proliferate for more days. A sub-confluent culture of cells was trypsinized and re-cultured. The MSCs were characterized by the expression of specific markers with flow cytometry. The osteogenic differentiation of MSCs was also validated by alkaline phosphatase and alizarian red S staining. Our results showed comparable expression of MSCs specific markers for both MSC sources (AM and BM). We also showed the optimum osteogenic differentiation of MSCs from both sources whereas hAM-MSCs revealed higher proliferation rate. We found no essential immunophenotypic differences between MSCs originated from bone marrow and amnion membrane while their differentiations into osteoblastic linage were also comparable. This was in addition to the higher proliferation rate observed for hAM-MSCs which suggests hAM as an easily accessible and reliable source of MSCs applicable for bone engineering, regenerative medicine or other therapeutic approaches.

Cellular Therapeutics for Heart Failure: Focus on Mesenchymal Stem Cells

Resulting from a various etiologies, the most notable remains ischemia; heart failure (HF) manifests as the common end pathway of many cardiovascular processes and remains among the top causes for hospitalization and a major cause of morbidity and mortality worldwide. Current pharmacologic treatment for HF utilizes pharmacologic agents to control symptoms and slow further deterioration; however, on a cellular level, in a patient with progressive disease, fibrosis and cardiac remodeling can continue leading to end-stage heart failure. Cellular therapeutics have risen as the new hope for an improvement in the treatment of HF. Mesenchymal stem cells (MSCs) have gained popularity given their propensity of promoting endogenous cellular repair of a myriad of disease processes via paracrine signaling through expression of various cytokines, chemokines, and adhesion molecules resulting in activation of signal transduction pathways. While the exact mechanism remains to be completely elucidated, this remains the primary mechanism identified to date. Recently, MSCs have been incorporated as the central focus in clinical trials investigating the role how MSCs can play in the treatment of HF. In this review, we focus on the characteristics of MSCs that give them a distinct edge as cellular therapeutics and present results of clinical trials investigating MSCs in the setting of ischemic HF.

Biological properties of cardiac mesenchymal stem cells in rats with diabetic cardiomyopathy

Cardiomyopathy is a major outcome in patients with diabetes mellitus (DM) and contributes to the high morbidity/mortality observed in this disease.

AIMS

To evaluate several biological properties of cardiac mesenchymal stem cells (cMSCs) in a rat model of streptozotocin-induced DM with concomitant diabetic cardiomyopathy.

MAIN METHODS

After 10weeks of DM induction, diabetic and control rats were assessed using ECG and ventricular hemodynamics monitoring. Then, the hearts were excised and processed for histology and for extracting non-cardiomyocytic cells. A pool of these cells was plated for a colony forming units-fibroblasts (CFU-F) assay in order to estimate the number of cMSCs. The remaining cells were expanded to assess their proliferation rate as well as their osteogenic and adipogenic differentiation ability.

KEY FINDINGS

DM rats presented intense hyperglycemia and changes in ECG, LV hemodynamic, cardiac mass index and fibrosis, indicating presence of DCM. The CFU-F assay revealed a higher number of cardiac CFU-Fs in DM rats (10.4±1.1CFU-F/10⁵ total cells versus 7.6±0.7CFU-F/10⁵ total cells in control rats, p<0.05), which was associated with a significantly higher proliferative rate of cMSCs in DM rats. In contrast, cMSCs from DM rats presented a lower capacity to differentiate into both osteogenic (20.8±4.2% versus 10.1±1.0% in control rats, p<0.05) and adipogenic lineages (4.6±1.0% versus 1.3±0.5% in control rats, p<0.05).

SIGNIFICANCE

The findings suggest, for the first time, that in chronic DM rats with overt DCM, cMSCs increase in number and exhibit changes in several functional properties, which could be implicated in the pathogenesis of diabetic cardiomyopathy.

Inflammatory Conditions Dictate the Effect of Mesenchymal Stem or Stromal Cells on B Cell Function

The immunomodulatory capacity of mesenchymal stem or stromal cells (MSC) makes them a promising tool for treatment of immune disease and organ transplantation. The effects of MSC on B cells are characterized by an abrogation of plasmablast formation and induction of regulatory B cells (Bregs). It is, however, unknown how MSC interact with B cells under inflammatory conditions. In this study, adipose tissue-derived MSC were pretreated with 50 ng/ml IFN-γ for 96 h (MSC–IFN-γ) to simulate inflammatory conditions. Mature B cells were obtained from spleens by CD43⁻ selection. B cells were co-cultured with MSC and stimulated with anti-IgM, anti-CD40, and IL-2; and after 7 days, B cell proliferation, phenotype, Immunoglobulin-G (IgG), and IL-10 production were analyzed. MSC did not inhibit B cell proliferation but increased the percentage of CD38^high CD24^high B cells (Bregs) and IL-10 production, while MSC–IFN-γ significantly reduced B cell proliferation and inhibited IgG production by B cells in a more potent fashion but did not induce Bregs or IL-10 production. Both MSC and MSC–IFN-γ required proximity to target cells and being metabolically active to exert their effects. Indoleamine 2,3 dioxygenase expression was highly induced in MSC–IFN-γ and was responsible of the anti-proliferative and Breg reduction since addition of tryptophan (TRP) restored MSC properties. Immunological conditions dictate the effect of MSC on B cell function. Under immunological quiescent conditions, MSC stimulate Breg induction; whereas, under inflammatory conditions, MSC inhibit B cell proliferation and maturation through depletion of TRP. This knowledge is useful for customizing MSC therapy for specific purposes by appropriate pretreatment of MSC.

Determination of optimized oxygen partial pressure to maximize the liver regenerative potential of the secretome obtained from adipose-derived stem cells

BACKGROUND

A hypoxic-preconditioned secretome from stem cells reportedly promotes the functional and regenerative capacity of the liver more effectively than a control secretome. However, the optimum oxygen partial pressure (pO₂) in the cell culture system that maximizes the therapeutic potential of the secretome has not yet been determined.

METHODS

We first determined the cellular alterations in adipose tissue-derived stem cells (ASCs) cultured under different pO₂ (21%, 10%, 5%, and 1%). Subsequently, partially hepatectomized mice were injected with the secretome of ASCs cultured under different pO₂, and then sera and liver specimens were obtained for analyses.

RESULTS

Of all AML12 cells cultured under different pO₂, the AML12 cells cultured under 1% pO₂ showed the highest mRNA expression of proliferation-associated markers (IL-6, HGF, and VEGF). In the cell proliferation assay, the AML12 cells cultured with the secretome of 1% pO₂ showed the highest cell proliferation, followed by the cells cultured with the secretome of 21%, 10%, and 5% pO₂, in that order. When injected into the partially hepatectomized mice, the 1% pO₂ secretome most significantly increased the number of Ki67-positive cells, reduced serum levels of proinflammatory mediators (IL-6 and TNF-α), and reduced serum levels of liver transaminases. In addition, analysis of the liver specimens indicated that injection with the 1% pO₂ secretome maximized the expression of the intermediate molecules of the PIP3/Akt and IL-6/STAT3 signaling pathways, all of which are known to promote liver regeneration.

CONCLUSIONS

The data of this study suggest that the secretome of ASCs cultured under 1% pO₂ has the highest liver reparative and regenerative potential of all the secretomes tested here.

Mesenchymal Stromal Cells as Anti-Inflammatory and Regenerative Mediators for Donor Kidneys During Normothermic Machine Perfusion

There is great demand for transplant kidneys for the treatment of end-stage kidney disease patients. To expand the donor pool, organs from older and comorbid brain death donors, so-called expanded criteria donors (ECD), as well as donation after circulatory death donors, are considered for transplantation. However, the quality of these organs may be inferior to standard donor organs. A major issue affecting graft function and survival is ischemia/reperfusion injury, which particularly affects kidneys from deceased donors. The development of hypothermic machine perfusion has been introduced in kidney transplantation as a preservation technique and has improved outcomes in ECD and marginal organs compared to static cold storage. Normothermic machine perfusion (NMP) is the most recent evolution of perfusion technology and allows assessment of the donor organ before transplantation. The possibility to control the content of the perfusion fluid offers opportunities for damage control and reparative therapies during machine perfusion. Mesenchymal stromal cells (MSC) have been demonstrated to possess potent regenerative properties via the release of paracrine effectors. The combination of NMP and MSC administration at the same time is a promising procedure in the field of transplantation. Therefore, the MePEP consortium has been created to study this novel modality of treatment in preparation for human trials. MePEP aims to assess the therapeutic effects of MSC administered ex vivo by NMP in the mechanisms of injury and repair in a porcine kidney autotransplantation model.

Preconditioning of adipose tissue-derived mesenchymal stem cells with deferoxamine increases the production of pro-angiogenic, neuroprotective and anti-inflammatory factors: Potential application in the treatment of diabetic neuropathy

Diabetic neuropathy (DN) is one of the most frequent and troublesome complications of diabetes mellitus. Evidence from diabetic animal models and diabetic patients suggests that reduced availability of neuroprotective and pro-angiogenic factors in the nerves in combination with a chronic pro-inflammatory microenvironment and high level of oxidative stress, contribute to the pathogenesis of DN. Mesenchymal stem cells (MSCs) are of great interest as therapeutic agents for regenerative purposes, since they can secrete a broad range of cytoprotective and anti-inflammatory factors. Therefore, the use of the MSC secretome may represent a promising approach for DN treatment. Recent data indicate that the paracrine potential of MSCs could be boosted by preconditioning these cells with an environmental or pharmacological stimulus, enhancing their therapeutic efficacy. In the present study, we observed that the preconditioning of human adipose tissue-derived MSCs (AD-MSCs) with 150μM or 400μM of the iron chelator deferoxamine (DFX) for 48 hours, increased the abundance of the hypoxia inducible factor 1 alpha (HIF-1α) in a concentration dependent manner, without affecting MSC morphology and survival. Activation of HIF-1α led to the up-regulation of the mRNA levels of pro-angiogenic factors like vascular endothelial growth factor alpha and angiopoietin 1. Furthermore this preconditioning increased the expression of potent neuroprotective factors, including nerve growth factor, glial cell-derived neurotrophic factor and neurotrophin-3, and cytokines with anti-inflammatory activity like IL4 and IL5. Additionally, we observed that these molecules, which could also be used as therapeutics, were also increased in the secretome of MSCs preconditioned with DFX compared to the secretome obtained from non-preconditioned cells. Moreover, DFX preconditioning significantly increased the total antioxidant capacity of the MSC secretome and they showed neuroprotective effects when evaluated in an in vitro model of DN. Altogether, our findings suggest that DFX preconditioning of AD-MSCs improves their therapeutic potential and should be considered as a potential strategy for the generation of new alternatives for DN treatment.

Adipose derived stem cells for regenerative therapy in osteoarticular diseases

In the recent years, adipose derived stem cells (ASCs) led to significant findings in the field of regenerative therapy. ASCs have various biological properties and capacity as differentiation in three lineages (chondrocytes, osteocytes and adipocytes) or immunomodulation by releasing paracrine factors. Osteoarthritis (OA) is the most frequent osteoarticular disease characterized by none curative treatment. We reviewed all current data on the proof of concept of ASCs in OA pathophysiology as well as an inventory of ASC promising cell therapy in OA.

Mesenchymal Stem Cells Transplantation following Partial Hepatectomy: A New Concept to Promote Liver Regeneration-Systematic Review of the Literature Focused on Experimental Studies in Rodent Models

Mesenchymal stem cells (MSCs) are an attractive source for regenerative medicine because they are easily accessible through minimally invasive methods and have the potential to enhance liver regeneration (LG) and improve liver function, following partial hepatectomy (PH) and acute or chronic liver injury. A systematic review of the literature was conducted for articles published up to September 1st, 2016, using the MEDLINE database. The keywords that were used in various combinations were as follows: “Mesenchymal stem cells”, “transplantation”, “stem cells”, “adipose tissue derived stem cells”, “bone marrow-derived stem cells”, “partial hepatectomy”, “acute liver failure”, “chronic liver failure”, “liver fibrosis”, “liver cirrhosis”, “rats”, “mice”, and “liver regeneration”. All introduced keywords were searched for separately in MeSH Database to control relevance and terminological accuracy and validity. A total of 41 articles were identified for potential inclusion and reviewed in detail. After a strict selection process, a total of 28 articles were excluded, leaving 13 articles to form the basis of this systematic review. MSCs transplantation promoted LG and improved liver function. Furthermore, MSCs had the ability to differentiate in hepatocyte-like cells, increase survival, and protect hepatocytes by paracrine mechanisms. MSCs transplantation may provide beneficial effects in the process of LG after PH and acute or chronic liver injury. They may represent a new therapeutic option to treat posthepatectomy acute liver failure.

Comparative analysis of human mesenchymal stem cells from fetal-bone marrow, adipose tissue, and Warton's jelly as sources of cell immunomodulatory therapy

To characterize different tissue MSCs as sources of cell immunomodulatory therapy. Examined the effects of IFN-γ on WJ-MSC and their immunomodulatory function characteristics. We compared human fetal bone marrow (F-BM), adipose tissue (AT), and Warton's Jelly-derived MSCs (WJ-MSCs) for surface antigen expression, differentiation ability, proliferation capacity, clonality, tolerance for aging, gene expression, and whether IFN-γ affected WJ-MSC gene expression, as determined by real time quantitative PCR. Fifteen geneswere examined. We further assess WJ-MSCs-mediated immunomodulatory on peripheral blood mononuclear, stimulated by PHA, IL-2 and CD3Ab after 5 days of co-cultured in a 5:1 ratio (PBMC:MSCs). Examined the effect of WJ-MSCs on the Th1, Th2, Th17 cytokines production and Treg augument. MSCs from different tissues have similar levels of cell surface antigen expression and differentiation ability, while F-BM-MSCs and WJ-MSC had higher rates of cell proliferation and clonality than AD-MSCs. All 15 genes were expressed at similar levels in WJ-MSCs and AD-MSCs (P > 0.05). 9 genes were upregulated in WJ-MSCFor F-MSC, including IL-6, CXCL9, CXCL10, CXCL11, ICAM-1, IDO1, HLA-G5, SDF1A, and NOTCH were down expression, but VCAM-1 was lower expressionin WJ-MSCS. After IFN-γ treatment, 7 genes were upregulated in WJ-MSC, including chemokine ligands CXCL9, CXCL10 and CXCL11, and the adhesion protein VCAM1and ICAM1. Additionally, immunosuppressive factors, such as HLA-G and IDO were both increased. When cocultured with peripheral blood mononuclear, WJ-MSCs showed an immunosuppressive function by inhibit the proliferative response of Th1 and Th17 but augment Th2 and Treg. Primed WJ-MSCs by IFNγ caused a greater reduction in IFNγ and TNFα than untreated WJ-MSCs, also the effect on augument in Treg and inhibit Th17 (P < 0.01). Our results demonstrate that primitive F-BM-MSCs and WJ-MSCs have biological advantages as compared to adult cells, WJ-MSCs have a gene expression pattern similar to AT-MSCs but not F-BM MSCs, and that inflammatory stimuli regulate gene expression in WJ-MSCs. WJ-MSC showed the immunosuppressive function in co-cultured system with PBMC, and IFNγ can promoted the immunosuppressive function.

Mesenchymal Stem Cells Reversed Morphine Tolerance and Opioid-induced Hyperalgesia

More than 240 million opioid prescriptions are dispensed annually to treat pain in the US. The use of opioids is commonly associated with opioid tolerance (OT) and opioid-induced hyperalgesia (OIH), which limit efficacy and compromise safety. The dearth of effective way to prevent or treat OT and OIH is a major medical challenge. We hypothesized that mesenchymal stem cells (MSCs) attenuate OT and OIH in rats and mice based on the understanding that MSCs possess remarkable anti-inflammatory properties and that both OT and chronic pain are associated with neuroinflammation in the spinal cord. We found that the development of OT and OIH was effectively prevented by either intravenous or intrathecal MSC transplantation (MSC-TP), which was performed before morphine treatment. Remarkably, established OT and OIH were significantly reversed by either intravenous or intrathecal MSCs when cells were transplanted after repeated morphine injections. The animals did not show any abnormality in vital organs or functions. Immunohistochemistry revealed that the treatments significantly reduced activation level of microglia and astrocytes in the spinal cord. We have thus demonstrated that MSC-TP promises to be a potentially safe and effective way to prevent and reverse two of the major problems of opioid therapy.

Stem Cell Therapy for the Heart: Blind Alley or Magic Bullet?

When stressed by ageing or disease, the adult human heart is unable to regenerate, leading to scarring and hypertrophy and eventually heart failure. As a result, stem cell therapy has been proposed as an ultimate therapeutic strategy, as stem cells could limit adverse remodelling and give rise to new cardiomyocytes and vasculature. Unfortunately, the results from clinical trials to date have been largely disappointing. In this review, we discuss the current status of the field and describe various limitations and how future work may attempt to resolve these to make way to successful clinical translation.

Inactivated Mesenchymal Stem Cells Maintain Immunomodulatory Capacity

Mesenchymal stem cells (MSC) are studied as a cell therapeutic agent for treatment of various immune diseases. However, therapy with living culture-expanded cells comes with safety concerns. Furthermore, development of effective MSC immunotherapy is hampered by lack of knowledge of the mechanisms of action and the therapeutic components of MSC. Such knowledge allows better identification of diseases that are responsive to MSC treatment, optimization of the MSC product, and development of therapy based on functional components of MSC. To close in on the components that carry the therapeutic immunomodulatory activity of MSC, we generated MSC that were unable to respond to inflammatory signals or secrete immunomodulatory factors, but preserved their cellular integrity [heat-inactivated MSC (HI-MSC)]. Secretome-deficient HI-MSC and control MSC showed the same biodistribution and persistence after infusion in mice with ischemic kidney injury. Both control and HI-MSC induced mild inflammatory responses in healthy mice and dramatic increases in interleukin-10, and reductions in interferon gamma levels in sepsis mice. In vitro experiments showed that opposite to control MSC, HI-MSC lacked the capability to suppress T-cell proliferation or induce regulatory B-cell formation. However, both HI-MSC and control MSC modulated monocyte function in response to lipopolysaccharides. The results of this study demonstrate that, in particular disease models, the immunomodulatory effect of MSC does not depend on their secretome or active cross-talk with immune cells, but on recognition of MSC by monocytic cells. These findings provide a new view on MSC-induced immunomodulation and help identify key components of the therapeutic effects of MSC.

Adipose Mesenchymal Stromal Cell-Based Therapy for Severe Osteoarthritis of the Knee: A Phase I Dose-Escalation Trial

: Osteoarthritis (OA) is the most widespread musculoskeletal disorder in adults. It leads to cartilage damage associated with subchondral bone changes and synovial inflammation, causing pain and disability. The present study aimed at evaluating the safety of a dose-escalation protocol of intra-articular injected adipose-derived stromal cells (ASCs) in patients with knee OA, as well as clinical efficacy as secondary endpoint. A bicentric, uncontrolled, open phase I clinical trial was conducted in France and Germany with regulatory agency approval for ASC expansion procedure in both countries. From April 2012 to December 2013, 18 consecutive patients with symptomatic and severe knee OA were treated with a single intra-articular injection of autologous ASCs. The study design consisted of three consecutive cohorts (six patients each) with dose escalation: low dose (2 × 10(6) cells), medium dose (10 × 10(6)), and high dose (50 × 10(6)). The primary outcome parameter was safety evaluated by recording adverse events throughout the trial, and secondary parameters were pain and function subscales of the Western Ontario and McMaster Universities Arthritis Index. After 6 months of follow-up, the procedure was found to be safe, and no serious adverse events were reported. Four patients experienced transient knee joint pain and swelling after local injection. Interestingly, patients treated with low-dose ASCs experienced significant improvements in pain levels and function compared with baseline. Our data suggest that the intra-articular injection of ASCs is a safe therapeutic alternative to treat severe knee OA patients. A placebo-controlled double-blind phase IIb study is being initiated to assess clinical and structural efficacy.

SIGNIFICANCE

Although this phase I study included a limited number of patients without a placebo arm, it showed that local injection of autologous adipose-derived stem cells was safe and well tolerated in patients with knee osteoarthritis. This study also provides encouraging preliminary evidence of efficacy. Larger and controlled long-term studies are now mandatory to confirm whether this new strategy of cell therapy can improve pain and induce structural benefit in osteoarthritis.

Mitochondrial Transfer via Tunneling Nanotubes is an Important Mechanism by Which Mesenchymal Stem Cells Enhance Macrophage Phagocytosis in the In Vitro and In Vivo Models of ARDS

Mesenchymal stromal cells (MSC) have been reported to improve bacterial clearance in preclinical models of Acute Respiratory Distress Syndrome (ARDS) and sepsis. The mechanism of this effect is not fully elucidated yet. The primary objective of this study was to investigate the hypothesis that the antimicrobial effect of MSC in vivo depends on their modulation of macrophage phagocytic activity which occurs through mitochondrial transfer. We established that selective depletion of alveolar macrophages (AM) with intranasal (IN) administration of liposomal clodronate resulted in complete abrogation of MSC antimicrobial effect in the in vivo model of Escherichia coli pneumonia. Furthermore, we showed that MSC administration was associated with enhanced AM phagocytosis in vivo. We showed that direct coculture of MSC with monocyte‐derived macrophages enhanced their phagocytic capacity. By fluorescent imaging and flow cytometry we demonstrated extensive mitochondrial transfer from MSC to macrophages which occurred at least partially through tunneling nanotubes (TNT)‐like structures. We also detected that lung macrophages readily acquire MSC mitochondria in vivo, and macrophages which are positive for MSC mitochondria display more pronounced phagocytic activity. Finally, partial inhibition of mitochondrial transfer through blockage of TNT formation by MSC resulted in failure to improve macrophage bioenergetics and complete abrogation of the MSC effect on macrophage phagocytosis in vitro and the antimicrobial effect of MSC in vivo. Collectively, this work for the first time demonstrates that mitochondrial transfer from MSC to innate immune cells leads to enhancement in phagocytic activity and reveals an important novel mechanism for the antimicrobial effect of MSC in ARDS. Stem Cells2016;34:2210–2223

Optimized Cryopreservation and Banking of Human Bone-Marrow Fragments and Stem Cells

Adult mesenchymal stem cells are a promising source for cell therapies and tissue engineering applications. Current procedures for banking of human bone-marrow mesenchymal stem cells (hBM-MSCs) require cell isolation and expansion, and thus the use of large amounts of animal sera. However, animal-derived culture supplements have the potential to trigger infections and severe immune reactions. The aim of this study was to investigate an optimized method for cryopreservation of human bone-marrow fragments for application in cell banking procedures where stem-cell expansion and use are not immediately needed. Whole trabecular fragments enclosing the bone marrow were stored in liquid nitrogen for 1 year in a cryoprotective solution containing a low concentration of dimethyl sulfoxide and a high concentration of human serum (HuS). After thawing, the isolation, colony-forming-unit ability, proliferation, morphology, stemness-related marker expression, cell senescence, apoptosis, and multi-lineage differentiation potential of hBM-MSCs were tested in media containing HuS compared with hBM-MSCs isolated from fresh fragments. Human BM-MSCs isolated from cryopreserved fragments expressed MSC markers until later passages, had a good proliferation rate, and exhibited the capacity to differentiate toward osteogenic, adipogenic, and myogenic lineages similar to hBM-MSCs isolated from fresh fragments. Moreover, the cryopreservation method did not induce cell senescence or cell death. These results imply that minimal processing may be adequate for the banking of tissue samples with no requirement for the immediate isolation and use of hBM-MSCs, thus limiting cost and the risk of contamination, and facilitating banking for clinical use. Furthermore, the use of HuS for cryopreservation and expansion/differentiation has the potential for clinical application in compliance with good manufacturing practice standards.