Adipose-derived mesenchymal stem/stromal cells: from the lab bench to the basic concepts for clinical translation

In the last years, much work has shown that the most effective repair system of the body is represented by stem cells, which are defined as undifferentiated precursors that own unlimited or prolonged self-renewal ability, which also have the potential to transform themselves into various cell types through differentiation.All tissues that form the body contain many different types of somatic cells, along with stem cells that are called ‘mesenchymal stem (or stromal) cells’ (MSC). In certain circumstances, some of these MSC migrate to injured tissues to replace dead cells or to undergo differentiation to repair it.The discovery of MSC has been an important step in regenerative medicine because of their high versatility. Moreover, the finding of a method to isolate MSC from adipose tissue, so called ‘adipose-derived mesenchymal stem cells’ (ASC), which share similar differentiation capabilities and isolation yield that is greater than other MSC, and less bioethical concerns compared to embryonic stem cells, have created self-praised publicity to procure almost any treatment with them. Here, we review the current techniques for isolation, culture and differentiation of human ASC (hASC), and describe them in detail. We also compile some advantages of the hASC over other stem cells, and provide some concepts that could help finding strategies to promote their therapeutic efficiency.     

Bones Morphogenic Protein‐4 and retinoic acid combined treatment comparative analysis for in vitro differentiation potential of murine mesenchymal stem cells derived from bone marrow and adipose tissue into germ cells

Nowadays, infertility is no longer considered as an unsolvable disorder due to progresses in germ cells derived from stem lineage with diverse origins. Technical and ethical challenges push researchers to investigate various tissue sources to approach more efficient gametes. The purpose of the current study is to investigate the efficacy of a combined medium, retinoic acid (RA) together with Bone Morphogenic Protein‐4 (BMP4), on differentiation of Bone Marrow Mesenchymal Stem Cells (BMMSCs) and adipose‐derived mesenchymal stem cells (ADMSCs) into germ cells. Murine MSCs were obtained from both Bone Marrow (BM) and Adipose Tissue (AT) samples and were analyzed for surface markers to get further verification of their nature. BMMSCs and ADMSCs were induced into osteogenic and adipogenic lineage cells respectively, to examine their multipotency. They were finally differentiated into germ cells using media enriched with BMP4 for 4 days followed by addition of RA for 7 days (11 days in total). Analyzing of differentiation potential of BMMSCs‐ and ADMSCs were performed via Immunofluorescence, Flowcytometry and Real time‐PCR techniques for germ cell‐specific markers (Mvh, Dazl, Stra8 and Scp3). Mesenchymal surface markers (CD90 and CD44) were expressed on both BMMSCs and ADMSCs, while endothelial and hematopoietic cell markers (CD31 and CD45) had no expression. Finally, all germ‐specific markers were expressed in both BM and AT. Although germ cells differentiated from ADMSCs showed faster growth and proliferation as well as easy collection, they significantly expressed germ‐specific markers lower than BMMSCs. This suggests stronger differentiation potential of murine BMMSCs than ADMSCs.     

Ultrastructural analysis of human bone marrow mesenchymal stem cells during in vitro osteogenesis and chondrogenesis

The main purpose of this article was to describe the morphology of mesenchymal stem cells (MSCs) differentiated in vitro towards osteogenic and chondrogenic lineages and to focus on the ultrastructural features associated with these processes. Human mononuclear cells (hMNC) were isolated, expanded, and analyzed for the expression of specific cell surface markers to demonstrate their stem cell characteristics. Human mononuclear cells were differentiated in vitro in an osteogenic and in a chondrogenic sense for 7, 14, 21, and 28 days. Subsequently, they were processed using electron microscopic analysis (FEISEM). Alizarin red and alcian blue staining were carried out to demonstrate the deposition of mineral salts and proteoglycans in the extracellular matrix. Undifferentiated MSCs showed a cell surface covered by filopodia and ondulopodia. During differentiation, the MSCs changed their shape from a round to a fibroblastic-like shape. At the end of the differentiation, several filaments with a parallel orientation in the osteogenic samples as well as a network organization in the chondrogenic samples were detected in the extracellular spaces. This study demonstrated that there are morphological features associated with the undifferentiated and differentiated states of the MSCs, which could be utilized as new parameters for identifying and classifying these cells.     

Dental pulp stem cells and banking of teeth as a lifesaving therapeutic vista

Exfoliated deciduous or an extracted healthy adult tooth can be used to harvest, process, and cryogenically preserve dental pulp stem cells. Future stem cell-based regenerative medicine methods could benefit significantly from these mesenchymal stem cells. Teeth serve as a substantial source of mesenchymal stem cells, otherwise disposed of as medical waste. Care should be taken to store this treasure trove of stem cells. Collective responsibility of patients, dentists, and physicians is necessary to ensure that this valuable resource is not wasted and that every possible dental pulp stem cell is available for use in the future. The dental pulp stem cells (DPSC) inside teeth represent a significant future source of stem cells for regenerative medicine procedures. This review describes the ontogeny, the laboratory processing and collection, and isolation methods of DPSC. This review also discusses currently available stem cell banking facilities and their potential use in regenerative medicine procedures in dental and general medical applications in the future.     

Astragaloside IV improves melanocyte differentiation from mouse bone marrow mesenchymal stem cells

Vitiligo results in an autoimmune disorder destructing skin pigment cells, melanocytes (Mcs). This study aimedto investigate whether Astragaloside IV (AIV) could efficiently induce differentiation of bone marrow mesenchymal stemcells (BMMSCs) into Mcs. BMMSCs were induced and differentiated into Mcs with 0.1, 0.2, and 0.4 mg/L AIV during150-day. Morphologic changes of differentiated cells were observed. Levels of some melanocytic specific genes (TRP-1,TRP-2, MART-1, Mitf) were measured with quantitative polymerase chain reaction (qPCR) at 90, 120, and 150 daysof induction. After 90-day induction, the differentiated cells with 0.4 mg/L AIV demonstrated the typical morphologyof Mcs, positive 3,4 dihydroxyphenylalanine staining, and positive staining of TRP-1, TRP-2, MART-1, and Mitf.After 90- and 120- days’ induction with 0.4 mg/L AIV, TRP-1 expression was significantly elevated (p < 0.01), andTRP-2 expression was significantly increased in 0.4 mg/L AIV-treated group compared to negative control (p < 0.01),0.1 mg/L (p < 0.01), and 0.2 mg/L (p < 0.01) AIV-treated groups. Moreover, MART-1 expression was significantlyup-regulated in 0.4 mg/L AIV-treated group compared to negative control, but without difference compared to 0.1mg/L (p > 0.05) and 0.2 mg/L (p > 0.05) AIV-treated groups. During 90 to 150- day induction, there were nosignificant differences for Mitf levels between AIV-treated groups and negative control (p > 0.05). In conclusion,90-day induction with 0.4 mg/L AIV up-regulated TRP-1, TRP-2, and MART-1 expression, indicating that AIV canefficiently induce Mcs differentiation from BMMSCs. These results provide experimental and theoretic evidence forAIV application in clinical vitiligo repigmentation treatment.     

Immunophenotypic,immunocytochemistry, ultrastructural,and cytogenetic characterization of mesenchymal stem cells from equine bone marrow

The aim of this study was to isolate, culture, and characterize mesenchymal stem cells (MSCs) from horse bone marrow (BM) using the techniques of flow cytometry, immunocytochemistry, cytogenetics, and electron microscopy. Immunophenotypic analysis revealed the presence of MSCs with high expression of the CD90 marker, lower expression of the CD44 marker, and absent expression of the CD34 marker. In assays of differentiation, the positive response to osteogenic (OST), chondrogenic (CDG), and adipogenic (ADP) differentiation signals was observed and characterized by deposition of calcium‐rich extracellular matrix (OST), proteoglycans and collagen II (CDG) and intracellular deposition of fat drops (ADP). In immunocytochemical characterization, MSCs were immunopositive for CD44, vimentin, and PCNA, and they were negative for CD13. In the ultrastructural analysis of MSCs, the most outstanding characteristic was the presence of rough endoplasmic reticulum with very dilated cisterns filled with a low electrodensity material. Additionally, MSCs had normal karyotypes (2n = 64) as evidenced by cytogenetic analysis, and aneuploidy in metaphase was not observed. The protocols for isolating, culturing, and characterizing equine MSCs used in this study were shown to be appropriate for the production of a cell population with a good potential for differentiation and without aneuploidy that can be used to study future cellular therapies. Microsc. Res. Tech. 76:618–624, 2013. © 2013 Wiley Periodicals, Inc.     

Exosomes derived from circBCRC-3-knockdown mesenchymal stem cells promoted macrophage polarization

Macrophages play an essential role in the myocardial ischemia-reperfusion injury (MIRI), and the macrophageshifting from M1 to M2 phenotypes might be a potential strategy for the treatment of MIRI. It has been reported thatmiR-182 plays an important role in MSC-Exo-associated macrophage polarization. As circBCRC-3 is a newlydiscovered circle RNA that worked as a sponge of miR-182, this research aimed to find if circBCRC-3 plays a role inMSC-Exo-associated macrophage polarization. Firstly, circBCRC-3 was identified by divergent primers inmesenchymal stem cells (MSCs). Secondly, the exosome of MSCs was isolated and identified by transmission electronmicroscopy (TEM), nanoparticle-tracking analysis, and western blotting analysis. The expression level of circBCRC-3in MSCexos was detected by RT-PCR. Finally, the polarization of the RAW264.7 cell phenotype was analyzed by flowcytometry. Moreover, we first identified circBCRC-3 in MSCs. The results further confirmed that MSCexo couldeffectively shift the macrophage polarization state from M1 towards the M2 phenotype, which indicated its rolein MIRI cure.     

Cell-surface ultrastructural changes during the in vitro neuron-like differentiation of rat bone marrow-derived mesenchymal stem cells

The neuron-like differentiation of bone marrow-derived mesenchymal stem cells (BMMSCs) has been extensively studied. However, the alternations of the cell-surface ultrastructures and the membrane tension/reservoir of the cells during this differentiation process are poorly understood. Therefore, atomic force microscopy (AFM) was utilized in this study to observe the cell-surface ultrastructural changes among rat bone marrow-derived mesenchymal stem cells (rBMMSCs), partially differentiated cells, and fully differentiated neuron-like cells. By analyzing the stiffness of plasma membranes, lamellipodial extensions, average heights of small membrane protrusions and relatively larger uplifted structures, and peak-peak spacing among protrusions and/or uplifted structures, we found that the membrane reservoir may potentially decrease upon the differentiation from rBMMSCs to partially differentiated cells and to fully differentiated neuron-like cells. The results may help to better understanding the membrane tension of various types of cells and related biological processes, such as membrane traffic, cell adhesion, motility, differentiation, among others. The data also implies that AFM may be a useful tool for evaluating membrane reservoir by imaging cell-surface ultrastructures.     

Response of donor and recipient cells after transplantation of cells to the ligament and tendon

The mechanical properties of healing ligaments and tendons are not comparable to those of normal tissue. To improve the quality of the ligament healing, therapeutic strategies include gene transfer or placement of mesenchymal stem cells at the healing site. Studies show that marker genes, growth factors, and antisense oligonucleotides can be delivered to both normal and healing ligaments and tendons by gene transfer. Cells with and without genetic modification have been successfully transplanted to ligaments and tendons and remain viable. Tendon healing can be improved using collagen gel implants seeded with autologous mesenchymal stem cells. Even though these early results are encouraging, more work is required regarding the response of the recipient site to donor cells or vectors.     

Phenotypic,morphological, and metabolic characterization of vascular-spheres from human vascular mesenchymal stem cells

The ability to form spheroids under non-adherent conditions is a well-known property of human mesenchymal stem cells (hMSCs), in addition to stemness and multilineage differentiation features. In the present study, we tested the ability of hMSCs isolated from the vascular wall (hVW-MSCs) to grow as spheres, and provide a characterization of this 3D model. hVW-MSCs were isolated from femoral arteries through enzymatic digestion. Spheres were obtained using ultra-low attachment and hanging drop methods. Immunophenotype and pluripotent genes (SOX-2, OCT-4, NANOG) were analyzed by immunocytochemistry and real-time PCR, respectively. Spheres histological and ultrastructural architecture were examined. Cell viability and proliferative capacity were measured using LIVE/DEATH assay and ki-67 proliferation marker. Metabolomic profile was obtained with liquid chromatography–mass spectrometry. In 2D, hVW-MSCs were spindle-shaped, expressed mesenchymal antigens, and displayed mesengenic potential. 3D cultures of hVW-MSCs were CD44⁺, CD105^low, CD90^low, exhibited a low propensity to enter the cell cycle as indicated by low percentage of ki-67 expression and accumulated intermediate metabolites pointing to slowed metabolism. The 3D model of hVW-MSCs exhibits stemness, dormancy and slow metabolism, typically observed in stem cell niches. This culture strategy can represent an accurate model to investigate hMSCs features for future clinical applications in the vascular field.     

Elemental distributions in femoral bone of rat under osteoporosis preventive treatments

One of the abnormalities of bone architecture is osteoporosis as occurring in post‐menopausal women. Especially long bones, such as femur, become more fragile and more prone to fracture. The efficiency of several osteoporosis preventative treatments based on oestrogen and progestin in bone structure and mineral recovery was studied using ovariectomized Wistar rats as an osteoporosis experimental model. Diagonal cross‐sections of the proximal epiphysis of femoral bones were analysed using nuclear microscopy techniques in order to map and determine the concentration profiles of P, Ca, S, Fe and Zn from the epiphysis to diaphysis and across the cortical and trabecular bone structures. In control animals (not ovariectomized), the S and Zn contents significantly characterized differences between cortical and trabecular bone structures, whereas P and Ca showed increased gradients from the epiphyseal region to the diaphysis. After ovariectomy the differences observed were differential according to the type of hormonal supplementation. A significant decrease in P and Ca contents and depletion of minor and trace minerals, such as S, Fe and Zn, were found for both cortical and trabecular bone structures after ovariectomy relative to controls. Bone mineral contents were reversed to control levels by synthetic oestrogen supplementation, and combined oestrogen and progesterone treatment. Recovery was more evident in the femoral epiphysis and neck than in the diaphysis. The use of oestrogen alone did not lead to bone recovery after ovariectomy. Alterations in bone mineral composition observed for animals receiving synthetic oestrogen and combined oestrogen and progesterone supplement might reflect beneficial structural changes in critical regions of long bones, mostly affected in post‐menopausal osteoporosis.     

Mesenchymal stem cells: As a multi-target cell therapy for clearing β-amyloid deposition in Alzheimer’s disease

Extracellular β-amyloid (Aβ) plaques and neurofibrillary tangles (NFTs) are the pathological hallmarks of Alzheimer’s disease (AD). Studies have shown that aggregates of extracellular Aβ can induce neuroinflammation mediated neurotoxic signaling through microglial activation and release of pro-inflammatory factors. Thus, modulation of Aβ might be a potential therapeutic strategy for modifying disease progression. Recently, a large number of reports have confirmed the beneficial effects of mesenchymal stem cells (MSCs) on AD. It is believed to reduce neuroinflammation, reduce Aβ amyloid deposits and NFTs, increase acetylcholine levels, promote neurogenesis, reduce neuronal damage, and improve working memory and cognition. In this review, we focus on the role of MSCs in clearing Aβ deposition. MSCs have the potential to modulate Aβ-related microenvironments via enhancement of autophagy, proteolysis of Aβ aggregates, phagocytic clearance of Aβ by microglial M2 polarization, decrease oxidative stress (OS), and correction of abnormal sphingolipid (SL) metabolism. With advantages in clinical applications, these data suggest that the use of MSCs as a multi-target modulator of Aβ would be an effective therapeutic approach in AD.     

Huge clusters of embryonic stem cells in human embryos: A morphologic study

Background: Nothing is known about huge clusters (HC) of embryonic stem cells (ESC) in human fetal organs (HFO). Aim: To know the status of HC‐ESC in HFO. Methods: Morphology and immunohistochemistry (IHC) in 32 HFO of 7–40 gestational weeks (GW). Results: HC‐ESC were seen in many HFO including central nervous system, spinal cords, spine, soft tissue, bone, skin, thyroid, lung, liver, pancreas, gall bladder, extrahepatic bile duct, adrenal, kidney, bladder, foregut, midgut, hindgut, female and male genital organs, and neurons. HC‐ESC's were composed of two populations depending on constituting cells. One were large cells with ample acidophilic cytoplasms with vesicular nuclei and nucleoli. The other were small cells with scant cytoplasm with hyperchromatic nuclei without nucleoli, resembling lymphocytes. The HC‐ESC were frequently showed neuronal differentiation. HC‐ESC were positive for NCAM, synaptophysin, NSE, chromogranin, PDGFRA, AFP, ErbB2, bcl‐2, KIT, MET. They were negative for CD45, CD3, CD20, EMA, CEA, CA19‐9, cytokeratin (CK) 7, CK8, CK18, CK19, MUC1, MUC2, MUC5AC, and MUC6. The mean Ki‐67 labeling index (LI) was 13% ± 7%. HC‐ESC showed a little glycogen but lacked mucins. These HC‐ESC were seen in 7–25 GW, and they were rarely seen in 26–40 GW. Conclusions: The morphology, IHC, and ontogeny of HC‐ESC were described. Microsc. Res. Tech. 77:825–831, 2014. © 2014 Wiley Periodicals, Inc.     

Exosomes from adipose tissue-derived stem/stromal cells: A key to future regenerative medicine

Advances in regenerative medicine correlate strongly with progress in the use of adipose tissue-derived mesenchymal stem/stromal cells. The range of therapeutic indications has also expanded over recent years. Numerous recent studies have highlighted the primary importance of paracrine secretion by these cells. Though it is interesting to compare the different types of such secretions, we believe that exosomes (extra-cellular vesicles possessing the same properties as their source cells) will likely be the main key in tomorrow’s cell therapy. Exosomes also have many advantages compared to the direct use of cells, making these particles a major target in fundamental and translational research.     

Comparative characterization of human fetal neural stem cells and induced neural stem cells from peripheral blood mononuclear cells

Human-induced neural stem cells (iNSCs) transplantation is a potential treatment of neurodegenerationdiseases. However, whether the reprogrammed cells have the same characterizations as human fetal neural stem cellsneeds further exploration. Here we isolated human fetal neural stem cells from aborted 12-week fetal brains andcompared with iNSCs reprogrammed from human peripheral blood mononuclear cells in gene expression, proliferationability, differentiation capacity, and the responses to tumor necrosis factor-α. We found that iNSCs and NSCs bothexpressed neural stem cell markers Nestin, SOX1, and SOX2. However, only iNSCs can be patterned into dopaminergicneurons and motor neurons. Furthermore, both iNSCs and NSCs can differentiate into oligodendrocyte progenitorcells. In addition, a low dose of tumor necrosis factor-α did not inhibit the proliferation and differentiation of iNSCsand NSCs. In conclusion, iNSCs have properties similar to, and even better than, fetal neural stem cells and may besuitable for disease modeling and transplantation.     

<i>miR-103-3p</i> regulates the differentiation of bone marrow mesenchymal stem cells in myelodysplastic syndrome

The pathogenesis of myelodysplastic syndrome (MDS) may be related to the abnormal expression of microRNAs(miRNAs), which could influence the differentiation capacity of mesenchymal stem cells (MSCs) towards adipogenic andosteogenic lineages. In this study, exosomes from bone marrow plasma were successfully extracted and identified.Assessment of miR-103-3p expression in exosomes isolated from BM in 34 MDS patients and 10 controls revealed its0.52-fold downregulation in patients with MDS compared with controls (NOR) and was downregulated 0.55-fold inMDS-MSCs compared with NOR-MSCs. Transfection of MDS-MSCs with the miR-103-3p mimic improved osteogenicdifferentiation and decreased adipogenic differentiation in vitro, while inhibition of miR-103-3p showed the oppositeresults in NOR-MSCs. Thus, the expression of miR-103-3p decreases in MDS BM plasma and MDS-MSCs, significantlyimpacting MDS-MSCs differentiation. The miR-103-3p mimics may boost MDS-MSCs osteogenic differentiation whileweakening lipid differentiation, thereby providing possible target for the treatment of MDS pathogenesis.     

Microenvironmental regulation of stem cells injected in the area at risk of neurodegenerative diseases

The complex mechanism of degenerative diseases and the non-specific modulation of regenerative targets aretopics that need to be elucidated in order to advance the use of stem cells in improvement of neurodegenerative diseases.From pre-transplantation through post-transplantation, there are many changes in the conditions, both inside andoutside of the stem cells that have not been carefully considered. This has hindered development in the field of celltherapy and regeneration. This viewpoint highlights the potential implications of intracellular and extracellularalterations of stem cells in transplanted areas at risk of neurodegenerative disease.