Human bone marrow mesenchymal stromal/stem cells: current clinical applications and potential for hematology

Effects of Bone Marrow Mesenchymal Stem Cell-Derived Exosomes in Central Nervous System Diseases

Central nervous system (CNS) diseases are one of the diseases that threaten human health. The delivery of drugs targeting the CNS has always been a significant challenge; the blood-brain barrier (BBB) is the main obstacle that must be overcome. The rise of bone marrow mesenchymal stem cell (BMSC) therapy has brought hope for the treatment of CNS diseases. However, the problems of low homing rate, susceptibility differentiation into astrocytes, immune rejection, and formation of iatrogenic tumors of transplanted BMSCs limit their clinical application. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) have become a hot research topic in the treatment of CNS diseases in recent years because of their excellent histocompatibility, low immunogenicity, ease of crossing the BBB, and their ability to serve as natural carriers for treatment. This article reviews the mechanisms of BMSC-Exos in CNS diseases and provides direction for further research.

Prostate Cancer Stem Cells: Biology and Treatment Implications

Stem cells differentiate into mature organ/tissue-specific cells at a steady pace under normal conditions, but their growth can be accelerated during the process of tissue healing or in the context of certain diseases. It is postulated that the proliferation and growth of carcinomas are sustained by the presence of a vital cellular compartment resembling stem cells residing in normal tissues: 'stem-like cancer cells' or cancer stem cells (CSCs). Mutations in prostate stem cells can lead to the formation of prostate cancer. Prostate CSCs (PCSCs) have been identified and partially characterized. These express surface markers include CD44, CD133, integrin α2β1, and pluripotency factors like OCT4, NANOG, and SOX2. Several signaling pathways are also over-activated, including Notch, PTEN/Akt/PI3K, RAS-RAF-MEK-ERK and HH. Moreover, PCSCs appear to induce resistance to radiotherapy and chemotherapy, while their presence has been linked to aggressive cancer behavior and higher relapse rates. The development of treatment policies to target PCSCs in tumors is appealing as radiotherapy and chemotherapy, through cancer cell killing, trigger tumor repopulation via activated stem cells. Thus, blocking this reactive stem cell mobilization may facilitate a positive outcome through cytotoxic treatment.

Preclinical Research of Stem Cells: Challenges and Progress

In recent years, great breakthroughs have been made in basic research and clinical applications of stem cells in regenerative medicine and other fields, which continue to inspire people to explore the field of stem cells. With nearly unlimited self-renewal ability, stem cells can generate at least one type of highly differentiated daughter cell, which provides broad development prospects for the treatment of human organ damage and other diseases. In the field of stem cell research, related technologies for inducing or isolating stem cells are relatively mature, and a variety of stable stem cell lines have been successfully constructed. To realize the full clinical application of stem cells as soon as possible, it is more and more important to further optimize each stage of stem cell research while conforming to Current Good Manufacture Practices (cGMP) standards. Here, we synthesized recent developments in stem cell research and focus on the introduction of xenogenicity in the preclinical research process and the remaining problems of various cell bioreactors. Our goal is to promote the development of technologies for xeno-free culture and clinical expansion of stem cells through in-depth discussion of current research. This review will provide new insight into stem cell research protocols and will contribute to the creation of efficient and stable stem cell expansion systems.

Genetic profiling of human bone marrow mesenchymal stromal cells after in vitro expansion in clinical grade human platelet lysate

Mesenchymal stromal cells (MSCs) are non-hematopoietic cells that have a broad therapeutic potential. To obtain sufficient cells for clinical application, they must be expanded ex vivo. In the initial expansion protocols described, fetal calf serum (FCS) was used as the reference growth supplement, but more recently different groups started to replace FCS with platelet lysate (PL). We investigated in this study the impact of the culture supplement on gene expression of MSCs. Human bone marrow derived MSCs were expanded in vitro in FCS and PL supplemented medium. We found that MSCs expanded in PL-containing medium (PL-MSCs) express typical MSC immunomorphological features and can migrate, as their counterparts expanded in FCS-containing medium, through a layer of endothelial cells in vitro. Additionally, they show an increased proliferation rate compared to MSCs expanded in FCS medium (FCS-MSCs). RNA sequencing performed for MSCs cultured in both types of expansion medium revealed a large impact of the choice of growth supplement on gene expression: 1974 genes were at least twofold up- or downregulated. We focused on impact of genes involved in apoptosis and senescence. Our data showed that PL-MSCs express more anti-apoptotic genes and FCS-MSCs more pro-apoptotic genes. FCS-MSCs showed upregulation of senescence-related genes after four passages whereas this was rarer in PL-MSCs at the same timepoint. Since PL-MSCs show higher proliferation rates and anti-apoptotic gene expression, they might acquire features that predispose them to malignant transformation. We screened 10 MSC samples expanded in PL-based medium for the presence of tumor-associated genetic variants using a 165 gene panel and detected only 21 different genetic variants. According to our analysis, none of these were established pathogenic mutations. Our data show that differences in culture conditions such as growth supplement have a significant impact on the gene expression profile of MSCs and favor the use of PL over FCS for expansion of MSCs.

Scanning Probe Microscopy Bone Marrow Determination of Steogenic Differentiation of Mesenchymal Stem Cells

To address the question of determining the osteogenic differentiation of mesenchymal stem cells, the bone marrow studies were performed using probe microscopy. All adherent bone marrow was used to isolate the bone marrow mesenchymal stem cells and expanded and purified in vitro. Its morphology under an inverted microscope was observed. We used Zuogui Pills to differentiate the separation methods. Alcian blue staining, modified calcium cobalt alkaline phosphatase staining, and neuron-specific enolase immunohistochemical staining were performed. The experimental results are shown below. The morphology of the isolated and purified cells was analyzed with an inverted microscope, and the isolated and purified cells were analyzed with Zuogui Pill. Alcian blue staining, modified calcium cobalt alkaline phosphatase staining, and neuron-specific enolase immunohistochemical staining confirmed that the cells differentiated into cartilage and osteoblasts, and the cell structure and morphology were similar to those of the bone marrow mesenchymal stem cells. The results showed that the adherent mode of cells obtained from the whole bone marrow was the rat bone marrow mesenchymal stem cells, and the Zuogui Pills could induce multidirectional differences in the bone marrow mesenchymal stem cells.

Phenotypic and Functional Characterizations of Mesenchymal Stem/Stromal Cells Isolated From Human Cranial Bone Marrow

Mesenchymal stem/stromal cells (MSCs) are adult stem cells that were originally isolated from bone marrow. In contrast to long bone-derived MSCs that have been extensively characterized, our knowledge regarding to MSCs isolated from flat bones (e.g., cranial bones) remain less clear. In this study, MSCs were purified from human cranial bone marrow (CB-MSCs) and their transdifferentiation capacity and immunomodulatory functions were further characterized. Phenotypic analysis of CB-MSCs demonstrated high expression of CD73, CD90, and CD105 while negative for CD14, CD34, and HLA-DR. Further in vitro differentiation assay shown that CB-MSCs capable of differentiating into cell types of mesenchymal origin (i.e., adipocytes, osetoblasts, and chondrocytes) and collectively, these results indicated that cells isolated from cranial bone marrow in this study are bona fide MSCs according to the minimal criteria proposed by the International Society for Cellular Therapy. Following in vitro expansion, single colony-derived CB-MSCs (scCB-MSCs) were obtained and confocal microscopy analysis further revealed functional heterogeneity within primary CB-MSCs. Specifically, obtained scCB-MSCs exhibited GABA progenitor features, as determined by olig2 and nestin. As expect, scCB-MSCs were readily induced to differentiate into GABAergic neuron-like cells. Furthermore, immunomodulatory roles of scCB-MSCs were evaluated following co-culture with human peripheral blood lymphocytes and results shown that co-culturing with scCB-MSCs significantly suppressed lymphocyte proliferation and promoted differentiation of lymphocytes into regulatory T cells but not Th1/Th17 phenotype. Overall, our results indicated that CB-MSCs exhibited clonal heterogeneity with marked propensity to differentiate into neural-like cells and this might represent promising candidates for the treatment of neurodegenerative diseases.

Characteristics of Mesenchymal Stem Cells Are Independent of Bone Marrow Storage Temperatures

Mesenchymal stem cells play an important role in regenerative medicine due to their capability of self-renewal and multipotent differentiation. For research or clinical application, bone marrow aspirates are harvested during elective surgeries to isolate MSCs. If an immediate purification of the MSCs is not possible, the bone marrow must be stored. Therefore, the aim of this study was to investigate possible differences of stem cell characteristics regarding the self-renewal capability, the adipogenic, chondrogenic, and osteogenic differentiation, and the expression of surface antigens after different storage conditions of the bone marrow aspirates. Three groups were analysed: the first group was purified immediately after harvesting, the other two groups were processed after they were stored 18 to 24 hours at 22°C (room temperature) or at 4°C. Comparisons between the groups were performed using the Kruskal-Wallis test for nonparametric data. The final results showed no significant difference between the different storage conditions. Therefore, storage of bone marrow aspirates for 18 to 24 hours at room temperature or 4°C is possible without loss of stem cell characteristics.

The red-light emitting diode irradiation increases proliferation of human bone marrow mesenchymal stem cells preserving their immunophenotype

PURPOSE

For effective clinical application of human bone marrow mesenchymal stem cells (hBM-MSCs), the enhancement of their proliferation in vitro together with maintaining the expression of their crucial surface antigens and differentiation potential is necessary. The present study aimed to investigate the effect of light-emitting diode (LED) irradiation on hBM-MSCs proliferation after two, five, or nine days post-irradiation.

MATERIALS AND METHODS

The hBM-MSCs were exposed to the LED light at 630 nm, 4 J/cm2, and power densities of 7, 17, or 30 mW/cm2. To assess the cell proliferation rate in the sham-irradiated and irradiated samples the cells metabolic activity and DNA content were determined. The number of apoptotic and necrotic cells in the samples was also evaluated. The expression of the crucial surface antigens of the hBM-MSCs up to nine days after irradiation at 4 J/cm2 and 17 mW/cm2 was monitored with flow cytometry. Additionally, the potential of hBM-MSCs for induced differentiation was measured.

RESULTS

When the metabolic activity was assayed, the significant increase in the cell proliferation rate by 31 and 50% after the irradiation with 4 J/cm2 and 17 mW/cm2, respectively, was observed at day five and nine when compared to the sham-irradiated cells (p < .05). Similarly, DNA content within the irradiated hBM-MSCs increased by 31 and 41% at day five and nine after the irradiation with 4 J/cm2 and 17 mW/cm2 in comparison to the sham-irradiated cells. LED irradiation did not change the expression of the crucial surface antigens of the hBM-MSCs up to nine days after irradiation at 4 J/cm2 and 17 mW/cm2. At the same experimental conditions, the hBM-MSCs maintain in vitro their capability for multipotential differentiation into osteoblasts, adipocytes, and chondrocytes.

CONCLUSION

Therefore, LED irradiation at a wavelength of 630 nm, energy density 4 J/cm2, and power density 17 mW/cm2 can effectively increase the number of viable hBM-MSCs in vitro.

miR-23a-3p regulated by LncRNA SNHG5 suppresses the chondrogenic differentiation of human adipose-derived stem cells via targeting SOX6/SOX5

Cartilage generation and degradation are controlled by miRNAs. Our previous study showed miR-23a-3p was downregulated during chondrogenic differentiation in chondrogenic human adipose-derived mesenchymal stem cells (hADSCs). In the present study, we explored the function of miR-23a-3p in chondrogenesis differentiation. The role of miR-23a-3p in chondrogenic differentiation potential of hADSCs was assessed by Alcian blue staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. We show that miR-23a-3p suppressed the chondrogenic differentiation of hADSCs. LncRNA SNHG5 interacted with miR-23a-3p, and suppression or overexpression of SNHG5 correlates with inhibition and promotion of hADSC chondrogenic differentiation, respectively. We have determined that SNHG5 can sponge miR-23a-3p to regulate the expression of SOX6/SOX5, transcription factors that play essential roles in chondrocyte differentiation. Furthermore, the overexpression of SNHG5 activates the JNK/MAPK/ERK pathway. In conclusion, miR-23a-3p regulated by lncRNA SNHG5 suppresses the chondrogenic differentiation of human adipose-derived stem cells via targeting SOX6/SOX5.

Role of Stem-Cell Transplantation in Leukemia Treatment

Stem cells (SCs) play a major role in advanced fields of regenerative medicine and other research areas. They are involved in the regeneration of damaged tissue or cells, due to their self-renewal characteristics. Tissue or cells can be damaged through a variety of diseases, including hematologic and nonhematologic malignancies. In regard to this, stem-cell transplantation is a cellular therapeutic approach to restore those impaired cells, tissue, or organs. SCs have a therapeutic potential in the application of stem-cell transplantation. Research has been focused mainly on the application of hematopoietic SCs for transplantation. Cord blood cells and human leukocyte antigen-haploidentical donors are considered optional sources of hematopoietic stem-cell transplantation. On the other hand, pluripotent embryonic SCs and induced pluripotent SCs hold promise for advancement of stem-cell transplantation. In addition, nonhematopoietic mesenchymal SCs play their own significant role as a functional bone-marrow niche and in the management of graft-vs-host disease effects during the posttransplantation process. In this review, the role of different types of SCs is presented with regard to their application in SC transplantation. In addition to this, the therapeutic value of autologous and allogeneic hematopoietic stem-cell transplantation is assessed with respect to different types of leukemia. Highly advanced and progressive scientific research has focused on the application of stem-cell transplantation on specific leukemia types. We evaluated and compared the therapeutic potential of SC transplantation with various forms of leukemia. This review aimed to focus on the application of SCs in the treatment of leukemia.

SIRT7 antagonizes human stem cell aging as a heterochromatin stabilizer

SIRT7, a sirtuin family member implicated in aging and disease, is a regulator of metabolism and stress responses. It remains elusive how human somatic stem cell populations might be impacted by SIRT7. Here, we found that SIRT7 expression declines during human mesenchymal stem cell (hMSC) aging and that SIRT7 deficiency accelerates senescence. Mechanistically, SIRT7 forms a complex with nuclear lamina proteins and heterochromatin proteins, thus maintaining the repressive state of heterochromatin at nuclear periphery. Accordingly, deficiency of SIRT7 results in loss of heterochromatin, de-repression of the LINE1 retrotransposon (LINE1), and activation of innate immune signaling via the cGAS-STING pathway. These aging-associated cellular defects were reversed by overexpression of heterochromatin proteins or treatment with a LINE1 targeted reverse-transcriptase inhibitor. Together, these findings highlight how SIRT7 safeguards chromatin architecture to control innate immune regulation and ensure geroprotection during stem cell aging.

Menatetrenone facilitates hematopoietic cell generation in a manner that is dependent on human bone marrow mesenchymal stromal/stem cells

Vitamin K2 in the form of menatetrenone has clinical benefits for osteoporosis and cytopenia. Given the dominant role of mesenchymal-osteolineage cells in the regulation of hematopoiesis, we investigated whether menatetrenone alters the hematopoiesis-supportive capability of human bone marrow mesenchymal stromal/stem cells (BM-MSCs). Menatetrenone up-regulated fibronectin protein expression in BM-MSCs without affecting their proliferation and differentiation capabilities. In addition, menatetrenone treatment of BM-MSCs enhanced generation of the CD34⁺ cell population in co-cultures through acceleration of the cell cycle. This effect was associated with cell-cell interactions mediated by VLA-4 and fibronectin. This proposal was supported by cytokine array and quantitative real-time PCR analyses, in which there were no significant differences between the expression levels of hematopoiesis-associated soluble factors in naïve and menatetrenone-treated BM-MSCs. Profiling of hematopoietic cells in co-cultures with menatetrenone-treated BM-MSCs demonstrated that they included significantly more CD34⁺CD38⁺ hematopoietic progenitor cells and cells skewed toward myeloid and megakaryocytic lineages than those in co-cultures with untreated BM-MSCs. Notably, myelodysplastic syndrome-derived cells were induced to undergo apoptosis when co-cultured with BM-MSCs, and this effect was enhanced by menatetrenone. Overall, our findings indicate that pharmacological treatment with menatetrenone bestows a unique hematopoiesis-supportive capability on BM-MSCs, which may contribute to the clinical improvement of cytopenia.

Direct differentiation of cord blood derived mesenchymal stem cells into keratinocytes without feeder layers and cAMP inducers

Objectives

The purpose of our study was isolation of umbilical cord blood derived mesenchymal stem (UCB-MSCs), their direct differentiation towards keratinocytes without using feeder layers, cAMP inducers and hormones known for morphological maintenance and proliferation of keratinocytes and characterization of UCB-MSCs through flowcytometry and keratinocytes through immunofluorescence.

Methods

We have isolated and cultured UCB-MSCs (n=4) following critical parameters for successful isolation like sample processing within an hour of collection, gestational age not more than 38 weeks, no co-morbid and blood volume at least 80 ml. Cord blood mononuclear cells were isolated through ficoll based density-gradient centrifugation then cultured to isolate MSCs, defined by minimum criteria of International Society for Cellular Therapy. UCB-MSCs were then differentiated directly into keratinocytes. Differentiation was confirmed by morphology and characterized through immunofluorescence staining. UCB samples were collected from gynae/obstetric ward of OJHA campus under sterile conditions and processed at Stem cells and Regenerative medicine Lab, Dow Research Institute of Biotechnology and Biomedical Sciences, Ojha campus. The total duration of study was approximately 12 months.

Results

We have successfully isolated UCB-MSCs that were plastic adherent, spindle shaped, showed trilineage mesodermal differentiation potential and were positive for CD90, CD73 and CD105 and negative for CD34 markers. UCB-MSCs were directly differentiated towards keratinocytes without using cAMP inducers, hormones or feeder layers. Differentiated keratinocytes attained typical honeycomb morphology and were stained positive on immunofluorescence for anti-pan cytokeratin antibody.

Conclusion

Our study concludes possibility of direct differentiation of isolated and cultured UCB-MSCs into keratinocytes without using feeder layers and conventional keratinocyte culture media.

An Update on the Progress of Isolation, Culture, Storage, and Clinical Application of Human Bone Marrow Mesenchymal Stem/Stromal Cells

Bone marrow mesenchymal stem/stromal cells (BMSCs), which are known as multipotent cells, are widely used in the treatment of various diseases via their self-renewable, differentiation, and immunomodulatory properties. In-vitro and in-vivo studies have supported the understanding mechanisms, safety, and efficacy of BMSCs therapy in clinical applications. The number of clinical trials in phase I/II is accelerating; however, they are limited in the size of subjects, regulations, and standards for the preparation and transportation and administration of BMSCs, leading to inconsistency in the input and outcome of the therapy. Based on the International Society for Cellular Therapy guidelines, the characterization, isolation, cultivation, differentiation, and applications can be optimized and standardized, which are compliant with good manufacturing practice requirements to produce clinical-grade preparation of BMSCs. This review highlights and updates on the progress of production, as well as provides further challenges in the studies of BMSCs, for the approval of BMSCs widely in clinical application.

A simple, efficient and economical method for isolating and culturing human umbilical cord blood‑derived mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) hold broad therapeutic potential in various diseases, however, it is difficult to produce sufficient numbers of MSCs for clinical application, therefore, improved culture systems are required. The present study aimed to develop a novel method for isolating and culturing human umbilical cord blood‑derived mesenchymal stromal cells (hUCB‑MSCs). A sequential culture method was developed that uses two types of culture media to optimize the isolation and culture of hUCB‑MSCs. First, DMEM supplemented with mesenchymal stem cell growth supplement was used to improve the colony formation and primary culture success rates of hUCB‑MSCs. Then, after removing the heterogeneous cell population, ordinary DMEM was used from the fourth passage. This method obtained hUCB‑MSCs with high culture efficiency and at a greatly reduced cost. The optimal culture conditions were determined and the hUCB‑MSCs were phenotypically characterized after passaging. Taken together, this simple, efficient and economical method can produce a large number of high‑quality hUCB‑MSCs in <1 month, therefore facilitating the future clinical applications of hUCB‑MSCs.

Diverse therapeutic efficacies and more diverse mechanisms of nicotinamide

BACKGROUND

Nicotinamide (NAM) is a form of vitamin B3 that, when administered at near-gram doses, has been shown or suggested to be therapeutically effective against many diseases and conditions. The target conditions are incredibly diverse ranging from skin disorders such as bullous pemphigoid to schizophrenia and depression and even AIDS. Similar diversity is expected for the underlying mechanisms. In a large portion of the conditions, NAM conversion to nicotinamide adenine dinucleotide (NAD⁺) may be a major factor in its efficacy. The augmentation of cellular NAD⁺ level not only modulates mitochondrial production of ATP and superoxide, but also activates many enzymes. Activated sirtuin proteins, a family of NAD⁺-dependent deacetylases, play important roles in many of NAM's effects such as an increase in mitochondrial quality and cell viability countering neuronal damages and metabolic diseases. Meanwhile, certain observed effects are mediated by NAM itself. However, our understanding on the mechanisms of NAM's effects is limited to those involving certain key proteins and may even be inaccurate in some proposed cases.

AIM OF REVIEW

This review details the conditions that NAM has been shown to or is expected to effectively treat in humans and animals and evaluates the proposed underlying molecular mechanisms, with the intention of promoting wider, safe therapeutic application of NAM.

KEY SCIENTIFIC CONCEPTS OF REVIEW

NAM, by itself or through altering metabolic balance of NAD⁺ and tryptophan, modulates mitochondrial function and activities of many molecules and thereby positively affects cell viability and metabolic functions. And, NAM administration appears to be quite safe with limited possibility of side effects which are related to NAM's metabolites.

The rate of fluid shear stress is a potent regulator for the differentiation of mesenchymal stem cells

We have previously demonstrated that the rate of fluid shear stress (ΔSS) can manipulate the fate of mesenchymal stem cells (MSCs) to osteogenic or chondrogenic cells. However, whether ΔSS is comparable to other two means of induction medium and substrate stiffness that have been proven to be potent in differentiation control is unknown. In this study, we subjected MSCs to 1-7 days of osteogenic or chondrogenic chemical induction, or 1-4 days of 37 or 86 kPa of substrate stiffness induction, followed by 20 min of Fast ΔSS (0-0') or Slow ΔSS (0-2'), which is a laminar FSS that linearly increased from 0 to 10 dyn/cm ² in 0 (Fast) or 2 min (Slow) and maintained at 10 dyn/cm ² for a total of 20 min. We found that 20 min of ΔSS could compete with 5 days' chemical and 2 days' substrate stiffness inductions. Our study confirmed that ΔSS is a powerful tool to control the differentiation of MSCs, which stressed the possible application in MSCs linage specification.

Up-regulation of FOXD1 by YAP alleviates senescence and osteoarthritis

Cellular senescence is a driver of various aging-associated disorders, including osteoarthritis. Here, we identified a critical role for Yes-associated protein (YAP), a major effector of Hippo signaling, in maintaining a younger state of human mesenchymal stem cells (hMSCs) and ameliorating osteoarthritis in mice. Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR associated protein 9 nuclease (Cas9)-mediated knockout (KO) of YAP in hMSCs resulted in premature cellular senescence. Mechanistically, YAP cooperated with TEA domain transcriptional factor (TEAD) to activate the expression of forkhead box D1 (FOXD1), a geroprotective protein. YAP deficiency led to the down-regulation of FOXD1. In turn, overexpression of YAP or FOXD1 rejuvenated aged hMSCs. Moreover, intra-articular administration of lentiviral vector encoding YAP or FOXD1 attenuated the development of osteoarthritis in mice. Collectively, our findings reveal YAP–FOXD1, a novel aging-associated regulatory axis, as a potential target for gene therapy to alleviate osteoarthritis.

The Hippo signalling effector YAP and the transcription factor FOXD1 play a role in alleviating cellular senescence and osteoarthritis, identifying the YAP-FOXD1 axis as a potential therapeutic target for aging-associated disorders.

Stem cell aging contributes to aging-associated degenerative diseases. Studies aiming to characterize the mechanisms of stem cell aging are critical for obtaining a comprehensive understanding of the aging process and developing novel strategies to treat aging-related diseases. As a prevalent aging-associated chronic joint disorder, osteoarthritis is a leading cause of disability. Senescent mesenchymal stem cells (MSCs) residing in the joint may be a critical target for the prevention of osteoarthritis; however, the key regulators of MSC senescence are little known, and targeting aging regulatory genes for the treatment of osteoarthritis has not yet been reported. Here, we show that Yes-associated protein (YAP), a major effector of Hippo signaling, represses human mesenchymal stem cell (hMSC) senescence through transcriptional up-regulation of forkhead box D1 (FOXD1). Lentiviral gene transfer of YAP or FOXD1 can rejuvenate aged hMSCs and ameliorate osteoarthritis symptoms in mouse models. We propose that the YAP–FOXD1 axis is a novel target for combating aging-associated diseases.

Enhancement of Replication and Differentiation Potential of Human Bone Marrow Stem Cells by Nicotinamide Treatment

Background and Objectives

Therapies using mesenchymal stem cells (MSCs) generally require substantial expansion of cell populations. However, the replicative life span of MSCs is limited and their multipotency declines over continued passages, imposing a limitation on their application especially in aged individuals. In an effort to increase MSC life span, we tested the effects of nicotinamide (NAM), a precursor of NAD⁺ that has been shown to reduce reactive oxygen species generation and delay the onset of replicative senescence in fibroblasts.

Methods

Bone marrow stem cells (BMSCs) from healthy donors were cultivated in the presence of 5 mM NAM until the end of their life span. The levels of proliferation and differentiation to osteogenic, adipogenic, and chondrogenic lineages of BMSCs were compared between populations incubated in the absence or presence of NAM.

Results

The replicative life span was substantially increased with a significant delay in the onset of senescence, and differentiation to all tested lineages was increased. Furthermore, differentiation was sustained and the adipogenic switch from osteogenesis to adipogenesis was attenuated in late-passage BMSCs.

Conclusions

NAM could be considered as an important biological agent to expand and sustain the multipotency of BMSCs and thus broaden the application of stem cells in cell therapies.

Recovery of Donor Hematopoiesis after Graft Failure and Second Hematopoietic Stem Cell Transplantation with Intraosseous Administration of Mesenchymal Stromal Cells

Multipotent mesenchymal stromal cells (MSCs) participate in the formation of bone marrow niches for hematopoietic stem cells. Donor MSCs can serve as a source of recovery for niches in patients with graft failure (GF) after allogeneic bone marrow (BM) transplantation. Since only few MSCs reach the BM after intravenous injection, MSCs were implanted into the iliac spine. For 8 patients with GF after allo-BMT, another hematopoietic stem cell transplantation with simultaneous implantation of MSCs from their respective donors into cancellous bone was performed. BM was aspirated from the iliac crest of these patients at 1-2, 4-5, and 9 months after the intraosseous injection of donor MSCs. Patients' MSCs were cultivated, and chimerism was determined. In 6 out of 8 patients, donor hematopoiesis was restored. Donor cells (9.4 ± 3.3%) were detected among MSCs. Thus, implanted MSCs remain localized at the site of administration and do not lose the ability to proliferate. These results suggest that MSCs could participate in the restoration of niches for donor hematopoietic cells or have an immunomodulatory effect, preventing repeated rejection of the graft. Perhaps, intraosseous implantation of MSCs contributes to the success of the second transplantation of hematopoietic stem cells and patient survival.

Muse Cell: A New Paradigm for Cell Therapy and Regenerative Homeostasis in Ischemic Stroke

Multilineage-differentiating stress enduring (Muse) cells are one of the most promising donor cells for cell therapy against ischemic stroke, because they can differentiate into any type of cells constructing the central nervous system (CNS), including the neurons. They can easily be isolated from the bone marrow stromal cells (BMSCs), which may also contribute to functional recovery after ischemic stroke as donor cells. In this chapter, we concisely review their biological features and then future perspective of Muse cell transplantation for ischemic stroke. In addition, we briefly refer to the surprising role of Muse cells to maintain the homeostasis in the living body under both physiological and pathological conditions.

Effects of Human Fibroblast-Derived Extracellular Matrix on Mesenchymal Stem Cells

Stem cell fate is largely determined by the microenvironment called niche. The extracellular matrix (ECM), as a key component in the niche, is responsible for maintaining structural stability and regulating cell proliferation, differentiation, migration and other cellular activities. Each tissue has a unique ECM composition for its needs. Here we investigated the effect of a bioengineered human dermal fibroblast-derived ECM (hECM) on the regulation of human mesenchymal stem cell (hMSC) proliferation and multilineage differentiation. Human MSCs were maintained on hECM for two passages followed by the analysis of mRNA expression levels of potency- and lineage-specific markers to determine the capacity of MSC stemness and differentiation, respectively. Mesenchymal stem cells pre-cultured with or without hECM were then induced and analyzed for osteogenesis, adipogenesis and chondrogenesis. Our results showed that compared to MSCs maintained on control culture plates without hECM coating, cells on hECM-coated plates proliferated more rapidly with a higher percentage of cells in S phase of the cell cycle, resulting in an increase in the CD90⁺/CD105⁺/CD73⁺/CD45^- subpopulation. In addition, hECM downregulated osteogenesis and adipogenesis of hMSCs but significantly upregulated chondrogenesis with increased production of collagen type 2. In sum, our findings suggest that hECM may be used to culture hMSCs for the application of cartilage tissue engineering.

Chemical and Physical Approaches to Extend the Replicative and Differentiation Potential of Stem Cells

Cell therapies using mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) are increasing in regenerative medicine, with applications to a growing number of aging-associated dysfunctions and degenerations. For successful therapies, a certain mass of cells is needed, requiring extensive ex vivo expansion of the cells. However, the proliferation of both MSCs and EPCs is limited as a result of telomere shortening-induced senescence. As cells approach senescence, their proliferation slows down and differentiation potential decreases. Therefore, ways to delay senescence and extend the replicative lifespan these cells are needed. Certain proteins and pathways play key roles in determining the replicative lifespan by regulating ROS generation, damage accumulation, or telomere shortening. And, their agonists and gene activators exert positive effects on lifespan. In many of the treatments, importantly, the lifespan is extended with the retention of differentiation potential. Furthermore, certain culture conditions, including the use of specific atmospheric conditions and culture substrates, exert positive effects on not only the proliferation rate, but also the extent of proliferation and differentiation potential as well as lineage determination. These strategies and known underlying mechanisms are introduced in this review, with an evaluation of their pros and cons in order to facilitate safe and effective MSC expansion ex vivo.

Effects of acute exposure to low-dose radiation on the characteristics of human bone marrow mesenchymal stromal/stem cells

Background

In recent years, increasing attention has been paid to the effects of low-dose irradiation on human health. We examined whether low-dose irradiation affected the functions of mesenchymal stromal/stem cells (MSCs), which are tissue/organ-supportive stem cells, derived from bone marrow (BM).

Methods

Normal human BM-MSCs from five healthy individuals were used in this study. Culture-expanded BM-MSCs were exposed to 0.1 gray (Gy) of γ-radiation (Cesium-137) at a rate of 0.8 Gy/min (Ir-MSCs), and their expansion, multi-differentiation, and hematopoiesis-supportive capabilities were investigated.

Results

The expansion of BM-MSCs was transiently delayed after low-dose γ-irradiation compared with that of non-irradiated BM-MSCs (non-Ir-MSCs) in two out of five lots. Adipogenic and osteogenic differentiation capabilities were not significantly affected by low-dose irradiation, although one lot of BM-MSCs tended to have transiently reduced differentiation. When human BM hematopoietic stem/progenitor cells (HPCs) were co-cultured with Ir-MSCs, the generation of CD34⁺CD38⁺ cells from HPCs was enhanced compared with that in co-cultures with non-Ir-MSCs in two out of five lots. The mRNA expression level of interleukin (IL)-6 was increased and those of stem cell factor (SCF) and fms-related tyrosine kinase 3 ligand (Flt3L) were decreased in the affected lots of Ir-MSCs. In the other three lots of BM-MSCs, a cell growth delay, enhanced generation of CD34⁺CD38⁺ cells from HPCs in co-culture, and a combination of increased expression of IL-6 and decreased expression of SCF and Flt3L were not observed. Of note, the characteristics of these affected Ir-MSCs recovered to a similar level as those of non-Ir-MSCs following culture for 3 weeks.

Conclusions

Our results suggest that acute exposure to low-dose (0.1 Gy) radiation can transiently affect the functional characteristics of human BM-MSCs.

CTLA4-CD28 chimera gene modification of T cells enhances the therapeutic efficacy of donor lymphocyte infusion for hematological malignancy

Donor lymphocyte infusion (DLI) followed by hematopoietic stem cell transplantation has served as an effective prevention/treatment modality against the relapse of some hematologic tumors, such as chronic myeloid leukemia (CML). However, the therapeutic efficacies of DLI for other types of leukemia, including acute lymphocytic leukemia (ALL), have been limited thus far. Therefore, we examined whether increasing the reactivity of donor T cells by gene modification could enhance the therapeutic efficacy of DLI in a murine model of ALL. When a CTLA4-CD28 chimera gene (CTC28) in which the intracellular signaling domain of CTLA4 was replaced with the CD28 signaling domain was introduced into CD4 and CD8 T cells in DLI, the graft-versus-tumor (GVT) effect was significantly increased. This effect was correlated with an increased expansion of donor CD8 T cells in vivo, and the depletion of CD8 T cells abolished this effect. The CD8 T cell expansion and the enhanced GVT effect were dependent on the transduction of both CD4 and CD8 T cells with CTC28, which emphasizes the role of dual modification in this therapeutic effect. The CTC28-transduced T cells that expanded in vivo also exhibited enhanced functionality. Although the potentiation of the GVT effect mediated by the CTC28 gene modification of T cells was accompanied by an increase of graft-versus-host disease (GVHD), the GVHD was not lethal and was mitigated by treatment with IL-10 gene-modified third-party mesenchymal stem cells. Thus, the combined genetic modification of CD4 and CD8 donor T cells with CTC28 could be a promising strategy for enhancing the therapeutic efficacy of DLI.

Neuron-Specific Fluorescence Reporter-Based Live Cell Tracing for Transdifferentiation of Mesenchymal Stem Cells into Neurons by Chemical Compound

Although transdifferentiation of mesenchymal stem cells (MSCs) into neurons increases the possibility of therapeutic use of MSCs for neurodevelopmental disorders, the use of MSCs has the limitation on differentiation efficiency to neuronal lineage and lack of an easy method to monitor the transdifferentiation. In this study, using time-lapse live cell imaging, we assessed the neuronal differentiation of MSCs induced by a small molecule “NHPDQC (N-hydroxy-2-oxo-3-(3-phenylprophyl)-1,2-dihydroquinoxaline-6-carboxamide, C₁₈H₁₇N₃O₃).” Plasmid vector containing red fluorescence reporter genes under the control of the tubulin α1 (Tα1) promoter (pTα1-DsRed2) traced the neuronal differentiation of MSCs. Two days after NHPDQC treatment, MSCs showed neuron-like phenotype with neurite outgrowth and high expression of neuron-specific markers in more than 95% cells. The fluorescence signals increased in the cytoplasm of pTα1-DsRed2-transfected MSCs after NHPDQC treatment. In vitro monitoring of MSCs along the time courses showed progressive increase of fluorescence till 30 h after treatment, corresponding with the increase in neurite length. We examined an efficient neuronal differentiation of MSCs by NHPDQC alone and monitored the temporal changes of neuronal differentiation by neuron-specific fluorescence reporter along time. This method would help further our understanding of the differentiation of MSCs to produce neurons by simple treatment of small molecule.

miR-301b~miR-130b-PPARγ axis underlies the adipogenic capacity of mesenchymal stem cells with different tissue origins

Mesenchymal stem cells (MSCs) have been widely used in regenerative medicine and cellular therapy due to their multi-lineage differentiation potential and immunomodulatory function. The applicability of MSCs also depends on their cellular sources and in vivo functions. Here in this study, we systematically compared the morphologic characteristics, immunophenotypes and the adipogenic differentiation of MSCs derived from umbilical cord (UC), adipose tissue (Ad) and bone marrow (BM). We found that the three tissues-derived MSCs displayed decreased adipogenic capacity in the order: Ad-MSC > BM-MSC > UC-MSC, and no morphologic and immunophenotypic differences were observed. Mechanistic investigation revealed a miR-301b~miR-130b-PPARγ axis, whose expression pattern in UC-MSC, Ad-MSC and BM-MSC significantly correlates with their adipogenic capacity. Our results come up with a potential mechanism to elucidate the differential adipogenesis of Ad-MSC, BM-MSC and UC-MSC, which would provide instructional advice for which source of MSCs to choose according to a certain clinical purpose. Furthermore, the miR-301b~miR-130b-PPARγ axis may also be used as a potential therapeutic target for the disorders associated with MSCs-mediated abnormal adipogenesis.

Translation, but not transfection limits clinically relevant, exogenous mRNA based induction of alpha-4 integrin expression on human mesenchymal stem cells

Mesenchymal stem cells (MSCs) represent promising resource of cells for regenerative medicine in neurological disorders. However, efficient and minimally invasive methods of MSCs delivery to the brain still have to be developed. Intra-arterial route is very promising, but MSCs are missing machinery for diapedesis through blood-brain barrier. Thus, here we have tested a mRNA-based method to induce transient expression of ITGA4, an adhesion molecule actively involved in cell extravasation. We observed that transfection with an ITGA4-mRNA construct bearing a conventional cap analogue (7-methylguanosine) failed to produce ITGA4 protein, but exogenous ITGA4-mRNA was detected in transfected MSCs. This indicates that not transfection, but rather translation being the major roadblock. Stabilization of ITGA4-mRNA with SSB proteins resulted in ITGA4 protein synthesis in HEK293 cells only, whereas in MSCs, satisfactory results were obtained only after using an anti-reverse-cap-analogue (ARCA). The presence of ITGA4 protein in MSCs was transient and lasted for up to 24 h after transfection. Membranous location was confirmed by flow cytometry of viable non-permeabilized cells using anti-ITGA4 antibody. The mRNA-based expression of itga4 transgene is potentially sufficient for diapedesis after intra-arterial delivery. To conclude, mRNA-based engineering of stem cells is a rapid and integration-free method and attractive from the perspective of potential future clinical application.

Isolation of mesenchymal stromal/stem cells from cryopreserved umbilical cord blood cells

Umbilical cord blood (UCB) has advantages over other tissues because it can be obtained without an invasive procedure and complex processing. We explored the availability of cryopreserved UCB cells as a source of mesenchymal stromal/stem cells (MSCs). MSCs were successfully isolated from six of 30 UCB units (median volume, 34.0 mL; median nucleated cell number, 4.4×10⁸) that were processed and cryopreserved using CP-1/human serum albumin. This isolation rate was lower than that (57%) from non-cryopreserved UCB cells. The number of nucleated cells before and after hydroxyethyl starch separation, UCB unit volume, and cell viability after thawing did not significantly differ between UCB units from which MSCs were successfully isolated and those from which they were not. When CryoSure-DEX40 was used as a cryoprotectant, MSCs were isolated from two of ten UCB units. Logistic regression analysis demonstrated that the cryopreservation method was not significantly associated with the success of MSC isolation. The isolated MSCs had a similar morphology and surface marker expression profile as bone marrow-derived MSCs and were able to differentiate into osteogenic, adipogenic, and chondrogenic cells. In summary, MSCs can be isolated from cryopreserved UCB cells. However, the cryopreservation process reduces the isolation rate; therefore, freshly donated UCB cells are preferable for the isolation of MSCs.

Knockdown of IL-8 Provoked Premature Senescence of Placenta-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have shown promise for use in cell therapy, and due to their tumor tropism can serve as vehicles for delivering therapeutic agents to tumor sites. Because interleukin-8 (IL-8) is known to mediate the protumor effect of MSCs, elimination of IL-8 secretion by MSCs may enhance their safety for use in cancer gene therapy. However, little is known concerning the effect of endogenously secreted IL-8 on MSCs. We performed studies using placenta-derived MSCs (PMSCs) to determine whether knockdown of IL-8 would influence their biological activity. We first verified that IL-8 and its membrane receptor CXCR2, but not CXCR1, were highly expressed in PMSCs. We then employed lentivirus-mediated small hairpin RNA interference to generate stable IL-8-silenced PMSCs, which displayed a variety of characteristic senescent phenotypes. We observed that at day 9 post-transfection, IL-8-silenced PMSCs had become larger and displayed a more flattened appearance when compared with their controls. Moreover, their proliferation, colony forming unit-fibroblast formation, adipogenic and osteogenic differentiation, and immunosuppressive potentials were significantly impaired. Enhanced senescence-associated β-galactosidase (SA-β-gal) activity and specific global gene expression profiles confirmed that IL-8 silencing evoked the senescence process in PMSCs. Increased levels of p-Akt and decreased levels of FOXO3a protein expression suggested that reactive oxygen species played a role in the initiation and maintenance of senescence in IL-8-silenced PMSCs. Notably, the majority of CXCR2 ligands were downregulated in presenescent IL-8-silenced PMSCs but upregulated in senescent cells, indicating an antagonistic pleiotropy of the IL-8/CXCR2 signaling pathway in PMSCs. This effect may promote the proliferation of young cells and accelerate senescence of old cells.

Pharmacological targeting of bone marrow mesenchymal stromal/stem cells for the treatment of hematological disorders

The therapeutic effects of mesenchymal stromal/stem cells (MSCs) are mainly based on three characteristics: immunomodulation, tissue regeneration, and hematopoietic support. Cell therapy using culture-expanded MSCs is effective in some intractable bone and hemato-immune disorders; however, its efficacy is limited. In this article, we review the previous efforts to improve the clinical outcomes of cell therapy using MSCs for such disorders. We describe pharmacological targeting of endogenous bone marrow-derived MSCs as a crucial quality-based intervention to establish more effective MSC-based therapies.

Extracellular vesicles and blood diseases

Extracellular vesicles (EVs) are small membrane vesicles released from many different cell types by the exocytic budding of the plasma membrane in response to cellular activation or apoptosis. EVs disseminate various bioactive effectors originating from the parent cells and transfer functional RNA and protein between cells, enabling them to alter vascular function and induce biological responses involved in vascular homeostasis. Although most EVs in human blood originate from platelets, EVs are also released from leukocytes, erythrocytes, endothelial cells, smooth muscle cells, and cancer cells. EVs were initially thought to be small particles with procoagulant activity; however, they can also evoke cellular responses in the immediate microenvironments and transport microRNAs (miRNA) into target cells. In this review, we summarize the recent literature relevant to EVs, including a growing list of clinical disorders that are associated with elevated EV levels. These studies suggest that EVs play roles in various blood diseases.

Effective tracking of bone mesenchymal stem cells in vivo by magnetic resonance imaging using melanin-based gadolinium3+ nanoparticles

Tracking transplanted stem cells is necessary to clarify cellular properties and improve transplantation success. In this study, we designed and synthesized melanin-based gadolinium³⁺ (Gd³⁺ )-chelate nanoparticles (MNP-Gd³⁺ ) of ∼7 nm for stem cell tracking in vivo. MNP-Gd³⁺ possesses many beneficial properties, such as its high stability and sensitivity, shorter T1 relaxation time, higher cell labeling efficiency, and lower cytotoxicity compared with commercial imaging agents. We found that the T1 relaxivity (r₁ ) of MNP-Gd³⁺ was significantly higher than that of Gd-DTPA; the nanoparticles were taken up by bone mesenchymal stem cells (BMSCs) via endocytosis and were broadly distributed in the cytoplasm. Based on an in vitro MTT assay, no cytotoxicity of labeled stem cells was observed for MNP-Gd³⁺ concentrations of less than 800 µg/mL. Furthermore, we tracked MNP-Gd³⁺ -labeled BMSCs in vivo using 3.0T MRI equipment. After intramuscular injection, MNP-Gd³⁺ -labeled BMSCs were detected, even after four weeks, by 3T MRI. We concluded that MNP-Gd³⁺ nanoparticles at appropriate concentrations can be used to effectively monitor and track BMSCs in vivo. MNP-Gd³⁺ nanoparticles have potential as a new positive MRI contrast agent in clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 131-137, 2017.

Therapeutic targets and emerging treatment options in gastrointestinal acute graft-versus-host disease

Introduction

Graft-versus-host disease (GVHD) continues to be the major lethal complication of allogeneic hematopoietic stem cell transplantation (HCT) but the standard of care, high dose steroids, has not changed in 40 years. Approximately 50% of GVHD patients will develop steroid refractory disease, typically involving the gastrointestinal (GI) tract, which has a very poor prognosis. Newly developed GVHD biomarker-based risk scores provide the first opportunity to treat patients at the onset of symptoms according to risk of steroid failure. Furthermore, improvements in our understanding of the pathobiology of GVHD, its different signaling pathways, involved cytokines, and the role of post-translational and epigenetic modifications, has identified new therapeutic targets for clinical trials.

Areas covered

This manuscript summarizes the pathophysiology, diagnosis, staging, current and new targeted therapies for GVHD, with an emphasis on GI GVHD. A literature search on PubMed was undertaken and the most relevant references included.

Expert Opinion

The standard treatment for GVHD, high dose steroids, offers less than optimal outcomes as well as significant toxicities. Better treatments, especially for GI GVHD, are needed to reduce non-relapse mortality after allogeneic HCT. The identification of high risk patients through a biomarker-defined scoring system offers a personalized approach to a disease that still requires significant research attention.

Current Opinion of Bone Marrow Stromal Cell Transplantation for Ischemic Stroke

This article reviews recent advancement and perspective of bone marrow stromal cell (BMSC) transplantation for ischemic stroke, based on current information of basic and translational research. The author would like to emphasize that scientific approach would enable us to apply BMSC transplantation into clinical situation in near future.