• Adipose
• Bone marrow
• Chemotherapy
• Hematopoiesis
• Mesenchymal stem cells (MSCs)

• Humans
• Mesenchymal Stem Cells/metabolism
• Mesenchymal Stem Cells/cytology
• Animals
• Mice
• Adipose Tissue/metabolism
• Adipose Tissue/cytology
• Hematopoiesis
• Umbilical Cord/cytology
• Umbilical Cord/metabolism
• Bone Marrow/metabolism
• Adipocytes/metabolism
• Adipocytes/cytology
• 3T3-L1 Cells
• STAT3 Transcription Factor/metabolism
• Mesenchymal Stem Cell Transplantation
• Coculture Techniques
• Janus Kinase 2/metabolism
• Hematopoietic Stem Cells/metabolism
• Hematopoietic Stem Cells/cytology

• YDZJSX2021B009 Science and Technology Department of Shanxi Province
• 2021XM07 Health Commission of Shanxi Province

• Glycolysis
• Mesenchymal stem cells
• PFK-158
• PFKFB3
• Pentose-phosphate pathway
• Polydatin metabolism

• Aging
• Hematopoietic stem cells
• Hormesis
• Mesenchymal stem cells
• Muscular stem cells
• Physical exercises
• Stem cell

• Humans
• Exercise/physiology
• Aging/physiology
• Cellular Senescence/physiology
• Animals
• Stem Cells/physiology

• Heart tissue
• Oxygen-releasing biomacromolecules
• Skin
• Tissue engineering
• Tumor therapy

• Tissue Engineering/methods
• Humans
• Tissue Scaffolds/chemistry
• Oxygen/chemistry
• Oxygen/metabolism
• Polymers/chemistry
• Regenerative Medicine/methods
• Animals
• Biocompatible Materials/chemistry
• Chitosan/chemistry

• axotomy
• cell-free therapy
• conditioned medium
• extracellular vesicles
• hypoxic preconditioning
• microrna
• oxygen-glucose deprivation
• peripheral nerve injury
• schwann cell precursors

• mesenchymal stem cells
• hypoxia
• osteoarthritis
• mesenchymal stem cells (mscs)
• chondrocytes
• mice model
• transplantations
• mmp-13
• apoptosis
• osteoarthritis (oa)
• cartilage damage
• swelling

• advanced therapy medicinal product (ATMP)
• cell therapy
• equipotency
• heterogeneity
• mesenchymal stromal (stem) cell
• pooling

• Adaptation
• Evolution
• HIF-1
• Hypoxia
• Metastasis

• Humans
• Neoplasms/pathology
• Neoplasms/genetics
• Neoplasms/metabolism
• Animals
• Neoplasm Metastasis
• Carcinogenesis/genetics
• Carcinogenesis/pathology
• Hypoxia-Inducible Factor 1/metabolism
• Hypoxia-Inducible Factor 1/genetics
• Neovascularization, Pathologic/genetics
• Neovascularization, Pathologic/pathology
• Neovascularization, Pathologic/metabolism
• Epithelial-Mesenchymal Transition/genetics
• Tumor Microenvironment/genetics
• Epigenesis, Genetic
• Gene Expression Regulation, Neoplastic

• R01 CA239219 NCI NIH HHS
• R21 CA269415 NCI NIH HHS
• R01 CA258089 NCI NIH HHS
• U54 CA274507 NCI NIH HHS

• adult cerebrospinal fluid
• artificial cerebrospinal fluid
• cell therapy
• cerebrospinal fluid
• embryonic cerebrospinal fluid
• neural stem cell
• neurological disorders

• BBB
• CNS
• Stem cells
• engineered
• exosomes

• Humans
• Exosomes
• Brain
• Blood-Brain Barrier
• Stem Cells
• Nervous System Diseases/therapy
• Brain Diseases

• WJ-MSCs
• differentiation
• epigenetic modifications
• signaling pathways
• transcriptional regulation

• Epigenesis, Genetic
• Wharton Jelly
• Cell Differentiation/genetics
• Mesenchymal Stem Cells
• Germ Layers

• 3D culture
• Wharton’s jelly
• amniotic epithelial cells
• amniotic membrane
• cell therapy
• co-culture spheroids
• perinatal cells
• placenta stem cells
• regenerative medicine
• type 1 diabetes
• umbilical cord

• cell manufacturing
• mesenchymal progenitor cells
• mesenchymal stromal cells
• proteomics
• stem cell metabolism

• biomaterials
• bone tissue engineering
• in vitro studies
• mesenchymal stem cells
• poly(3-hydroxybutyrate)
• polyhydroxyalkanoates
• scaffolds
• β tricalcium phosphate

Regenerating brain defects after traumatic brain injury (TBI) still remains a significant difficulty, which has motivated interest in 3D printing to design superior replacements for brain implantation. Collagen has been applied to deliver cells or certain neurotrophic factors for neuroregeneration. However, its fast degradation rate and poor mechanical strength prevent it from being an excellent implant material after TBI. In the present study, we prepared 3D-printed collagen/silk fibroin/hypoxia-pretreated human umbilical cord mesenchymal stem cells (HUCMSCs)-derived exosomes scaffolds (3D-CS-HMExos), which possessed favorable physical properties suitable biocompatibility and biodegradability and were attractive candidates for TBI treatment. Furthermore, inspired by exosomal alterations resulting from cells in different external microenvironments, exosomes were engineered through hypoxia stimulation of mesenchymal stem cells and were proposed as an alternative therapy for promoting neuroregeneration after TBI. We designed hypoxia-preconditioned (Hypo) exosomes derived from HUCMSCs (Hypo-MExos) and proposed them as a selective therapy to promote neuroregeneration after TBI. For the current study, 3D-CS-HMExos were prepared for implantation into the injured brains of beagle dogs. The addition of hypoxia-induced exosomes further exhibited better biocompatibility and neuroregeneration ability. Our results revealed that 3D-CS-HMExos could significantly promote neuroregeneration and angiogenesis due to the doping of hypoxia-induced exosomes. In addition, the 3D-CS-HMExos further inhibited nerve cell apoptosis and proinflammatory factor (TNF-α and IL-6) expression and promoted the expression of an anti-inflammatory factor (IL-10), ultimately enhancing the motor functional recovery of TBI. We proposed that the 3D-CS-loaded encapsulated hypoxia-induced exosomes allowed an adaptable environment for neuroregeneration, inhibition of inflammatory factors and promotion of motor function recovery in TBI beagle dogs. These beneficial effects implied that 3D-CS-HMExos implants could serve as a favorable strategy for defect cavity repair after TBI.

Rapid developments in stem cell research in recent years have provided a solid foundation for their use in medicine. Over the last few years, hundreds of clinical trials have been initiated in a wide panel of indications. Disorders and injuries of the nervous system still remain a challenge for the regenerative medicine. Neural stem cells (NSCs) are the optimal cells for the central nervous system restoration as they can differentiate into mature cells and, most importantly, functional neurons and glial cells. However, their application is limited by multiple factors such as difficult access to source material, limited cells number, problematic, long and expensive cultivation in vitro, and ethical considerations. On the other hand, according to the available clinical databases, most of the registered clinical trials involving cell therapies were carried out with the use of mesenchymal stem/stromal/signalling cells (MSCs) obtained from afterbirth or adult human somatic tissues. MSCs are the multipotent cells which can also differentiate into neuron-like and glia-like cells under proper conditions in vitro; however, their main therapeutic effect is more associated with secretory and supportive properties. MSCs, as a natural component of cell niche, affect the environment through immunomodulation as well as through the secretion of the trophic factors. In this review, we discuss various therapeutic strategies and activated mechanisms related to bilateral MSC–NSC interactions, differentiation of MSCs towards the neural cells (subpopulation of crest-derived cells) under the environmental conditions, bioscaffolds, or co-culture with NSCs by recreating the conditions of the neural cell niche.

• Adult
• Brain
• Cell Differentiation/physiology
• Humans
• Mesenchymal Stem Cells
• Nerve Regeneration
• Neural Stem Cells

The application of mesenchymal stem/stromal cells (MSC) in regenerative medicine offers hope for the effective treatment of incurable or difficult‐to‐heal diseases. However, it requires the development of unified protocols for both safe and efficient cell acquisition and clinical usage. The therapeutic effect of fat grafts (containing stem cells) in non‐healing wounds has been discussed in previous studies, although the application requires local or general anaesthesia. The treatment of MSC derived from adipose tissue (ASC) could be a less invasive method, and efficient delivery could lead to more favourable outcomes, which should encourage clinicians to use such therapeutic approaches more frequently. Therefore, the aim of this study was to optimise the methods of ASC isolation, culture and administration while maintaining their high survival, proliferation and colonisation potential. The ASC were isolated by an enzymatic method and were characterised according to International Society for Cellular Therapy and International Federation for Adipose Therapeutics and Science guidelines. To assess the opportunity to obtain a sufficient number of cells for transplantation, long‐term cell cultures in two oxygen concentrations (5% vs. 21%) were conducted. For these cultures, the population doubling time, the cumulative time for cell population doublings and the rate of cell senescence were estimated. In a developed and pre‐defined protocol, ASC can be efficiently cultured at physiological oxygen concentrations (5%), which leads to faster proliferation and slower cell senescence. Subsequently, to select the optimal and minimally invasive methods of ASC transplantation, direct cell application with an irrigator or with skin dressings was analysed. Our results confirmed that both the presented methods of cell application allow for the safe delivery of isolated ASC into wounds without losing their vitality. Cells propagated in the described conditions and applied in non‐invasive cell application (with an irrigation system and dressings) to treat chronic wounds can be a potential alternative or supplement to more invasive clinical approaches.

• cobalt chloride
• hypoxia
• mTOR
• mesenchymal stem cells
• metabolism

• Cell Differentiation
• Cell Hypoxia
• Cell Proliferation
• Cells, Cultured
• Humans
• Hypoxia/metabolism
• Mesenchymal Stem Cells/metabolism
• Oxygen/metabolism
• TOR Serine-Threonine Kinases/metabolism

• O2 tension
• hypoxia
• hypoxia in vitro models
• hypoxia inducible factors
• intracellular signaling
• metabolism
• stemness

• Animals
• Cell Differentiation/genetics
• Cell Differentiation/physiology
• Cell Hypoxia/genetics
• Cell Hypoxia/physiology
• Humans
• Oxygen/metabolism
• Stem Cells/metabolism

Stem/progenitor cells are usually cultured at atmospheric O₂ tension (21%); however, since physiologic O₂ tension in the heart is ∼5%, using 21% O₂ may cause oxidative stress and toxicity. Cardiac mesenchymal cells (CMCs), a newly discovered and promising type of progenitor cells, are effective in improving left ventricle (LV) function after myocardial infarction (MI). We have previously shown that, compared with 21% O₂, culture at 5% O₂ increases CMC proliferation, telomerase activity, telomere length, and resistance to severe hypoxia in vitro. However, it is unknown whether these beneficial effects of 5% O₂in vitro translate into greater therapeutic efficacy in vivo in the treatment of heart failure. Thus, murine CMCs were cultured at 21% or 5% O₂. Mice with heart failure caused by a 60-min coronary occlusion followed by 30 days of reperfusion received vehicle, 21% or 5% O₂ CMCs via echocardiography-guided intraventricular injection. After 35 days, the improvement in LV ejection fraction effected by 5% O₂ CMCs was > 3 times greater than that afforded by 21% O₂ CMCs (5.2 vs. 1.5 units, P < 0.01). Hemodynamic studies (Millar catheter) yielded similar results both for load-dependent (LV dP/dt) and load-independent (end-systolic elastance) indices. Thus, two independent approaches (echo and hemodynamics) demonstrated the therapeutic superiority of 5% O₂ CMCs. Further, 5% O₂ CMCs, but not 21% O₂ CMCs, significantly decreased scar size, increased viable myocardium, reduced LV hypertrophy and dilatation, and limited myocardial fibrosis both in the risk and non-infarcted regions. Taken together, these results show, for the first time, that culturing CMCs at physiologic (5%) O₂ tension provides superior therapeutic efficacy in promoting cardiac repair in vivo. This concept may enhance the therapeutic potential of CMCs. Further, culture at 5% O₂ enables greater numbers of cells to be produced in a shorter time, thereby reducing costs and effort and limiting cell senescence. Thus, the present study has potentially vast implications for the field of cell therapy.

• cardiac function
• cardiac mesenchymal cells
• cardiac repair
• heart failure
• myocardial infarction
• physiologic oxygen tension
• stem cells

• WJ-MSCs
• acute infection
• inflammation
• mesenchymal stem cells
• paracrine activity

• 2018/31/B/NZ4/03172 Narodowe Centrum Nauki

• Wharton’s jelly mesenchymal stem cells
• neuroprotection
• oxygen conditions
• secretory profile
• umbilical cord

• Cell Differentiation/drug effects
• Cell Lineage/drug effects
• Cell Proliferation/drug effects
• Cell Shape/drug effects
• Cells, Cultured
• Cellular Senescence/drug effects
• Clone Cells
• Humans
• Immunophenotyping
• Mesenchymal Stem Cells/cytology
• Mesenchymal Stem Cells/drug effects
• Mesenchymal Stem Cells/metabolism
• Neurons/cytology
• Neurons/drug effects
• Neurons/metabolism
• Neuroprotection
• Neuroprotective Agents
• Oxygen/pharmacology
• Wharton Jelly/cytology

• No. POIR.01.02.00-00-00024/17-00 Narodowe Centrum Badań i Rozwoju
• DWD/3/27/2019 Ministerstwo Nauki i Szkolnictwa Wyższego
• Statutury funds MMRI PAS

• 3D culture
• mesenchymal stem cells
• mesenchymal stromal cells
• neural
• neurospheres
• pluripotency
• quiescence
• spheroids

• Brainbow
• RNA sequencing
• fibrosis
• hindlimb ischemia
• platelet-derived growth factor receptor α
• regeneration
• revascularization

• angiogenesis
• dimethyloxalylglycine
• hypoxia
• mesenchymal stromal cells
• spheroids

Tuning stem cells microenvironment in vitro may influence their regenerative properties. In this study Wharton's Jelly-derived mesenchymal stem cells (WJ-MSCs) were encapsulated in 3D hydrogels derived from human fibrin (FB) or platelet lysate (PL) and the oxygen level was adjusted to physiological normoxia (5% O₂). The influence of the type of the scaffold and physiological normoxia conditions was tested on the WJ-MSCs' survivability, proliferation, migratory potential, the level of expression of selected trophic factors, cytokines, and neural markers. Encapsulated WJ-MSCs revealed high survivability, stable proliferation rate, and ability to migrate out of the hydrogel and the up-regulated expression of all tested factors, as well as the increased expression of neural differentiation markers. Physiological normoxia stimulated proliferation of encapsulated WJ-MSCs and significantly enhanced their neuronal, but not glial, differentiation. Ex vivo studies with indirect co-culture of organotypic hippocampal slices and cell-hydrogel bio-constructs revealed strong neuroprotective effect of WJ-MSCs against neuronal death in the CA1 region of the rat hippocampus. This effect was potentiated further by FB scaffolds under 5% O₂ conditions. Our results indicating significant effect of oxygen and 3D cytoarchitecture suggest the urgent need for further optimization of the microenvironmental conditions to improve therapeutical competence of the WJ-MSCs population.

Mesenchymal stem cells (MSC)-spheroid models favor maintenance of stemness, ex vivo expansion and transplantation efficacy. Spheroids may also be considered as useful surrogate models of the hematopoietic niche. However, accessibility to primary cells, from bone marrow (BM) or adipose tissues, may limit their experimental use and the lack of consistency in methods to form spheroids may affect data interpretation. In this study, we aimed to create a simple model by examining the ability of cell lines, from human (HS-27a and HS-5) and murine (MS-5) BM origins, to form spheroids, compared to primary human MSCs (hMSCs). Our protocol efficiently allowed the spheroid formation from all cell types within 24 hours. Whilst hMSC-spheroids began to shrink after 24 hours, the size of spheroids from cell lines remained constant during three weeks. The difference was partially explained by the balance between proliferation and cell death, which could be triggered by hypoxia and induced oxidative stress. Our results demonstrate that, like hMSCs, MSC cell lines make reproductible spheroids that are easily handled. Thus, this model could help in understanding mechanisms involved in MSC functions and may provide a simple model by which to study cell interactions in the BM niche.

• Animals
• Cell Aggregation
• Cell Death
• Cell Dedifferentiation
• Cell Hypoxia
• Cell Line
• Cell Proliferation
• Humans
• Mesenchymal Stem Cells/cytology
• Mice
• Oxidative Stress
• Spheroids, Cellular/cytology

• Ligue Contre le Cancer
• Ministère de l’Enseignement Supérieur, de la Recherche Scientifique et des Technologies de l'Information et de la Communication
• Fondation ARC
• Société Française d'Hématologie
• Lebanese south governate
• Ligue Contre le Cancer Grand-Ouest [16 (Charente), 36 (Indre), 37 (Indre-et-Loire), 41 (Loire et Cher), and 86 (Vendée)]
• Région Centre Val de Loire

Bone defects or atrophy may arise as a consequence of injury, inflammation of various etiologies, and neoplastic or traumatic processes or as a result of surgical procedures. Sometimes the regeneration process of bone loss is impaired, significantly slowed down, or does not occur, e.g., in congenital defects. For the bone defect reconstruction, a piece of the removed bone from ala of ilium or bone transplantation from a decedent is used. Replacement of the autologous or allogenic source of the bone-by-bone substitute could reduce the number of surgeries and time in the pharmacological coma during the reconstruction of the bone defect. Application of mesenchymal stem cells in the reconstruction surgery may have positive influence on tissue regeneration by secretion of angiogenic factors, recruitment of other MSCs, or differentiation into osteoblasts. Materials and Methods. Mesenchymal stem cells derived from the umbilical cord (Wharton's jelly (WJ-MSC)) were cultured in GMP-grade DMEM low glucose supplemented with heparin, 10% platelet lysate, glucose, and antibiotics. In vitro WJ-MSCs were seeded on the bone substitute Bio-Oss Collagen® and cultured in the StemPro® Osteogenesis Differentiation Kit. During the culture on the 1st, 7th, 14th, and 21st day (day in vitro (DIV)), we analyzed viability (confocal microscopy) and adhesion capability (electron microscopy) of WJ-MSC on Bio-Oss scaffolds, gene expression (qPCR), and secretion of proteins (Luminex). In vivo Bio-Oss® scaffolds with WJ-MSC were transplanted to trepanation holes in the cranium to obtain their overgrowth. The computed tomography was performed 7, 14, and 21 days after surgery to assess the regeneration.

The Bio-Oss® scaffold provides a favourable environment for WJ-MSC survival. WJ-MSCs in osteodifferentiation medium are able to attach and proliferate on Bio-Oss® scaffolds. Results obtained from qPCR and Luminex® indicate that WJ-MSCs possess the ability to differentiate into osteoblast-like cells and may induce osteoclastogenesis, angiogenesis, and mobilization of host MSCs. In animal studies, WJ-MSCs seeded on Bio-Oss® increased the scaffold integration with host bone and changed their morphology to osteoblast-like cells.

The presented construct consisted of Bio-Oss®, the scaffold with high flexibility and plasticity, approved for clinical use with seeded immunologically privileged WJ-MSC which may be considered reconstructive therapy in bone defects.

• gene regulation
• hypoxia
• mesenchymal stem cells
• transcription factors

There have been contradictory reports on the pro-cancer or anti-cancer effects of mesenchymal stem cells. In this study, we investigated whether conditioned medium (CM) from hypoxic human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) (H-CM) showed enhanced anti-cancer effects compared with CM from normoxic hUC-MSCs (N-CM).

Compared with N-CM, H-CM not only strongly reduced cell viability and increased apoptosis of human cervical cancer cells (HeLa cells), but also increased caspase-3/7 activity, decreased mitochondrial membrane potential (MMP), and induced cell cycle arrest. In contrast, cell viability, apoptosis, MMP, and cell cycle of human dermal fibroblast (hDFs) were not significantly changed by either CM whereas caspase-3/7 activity was decreased by H-CM. Protein antibody array showed that activin A, Beta IG-H3, TIMP-2, RET, and IGFBP-3 were upregulated in H-CM compared with N-CM. Intracellular proteins that were upregulated by H-CM in HeLa cells were represented by apoptosis and cell cycle arrest terms of biological processes of Gene Ontology (GO), and by cell cycle of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. In hDFs, negative regulation of apoptosis in biological process of GO and PI3K-Akt signaling pathway of KEGG pathways were represented.

H-CM showed enhanced anti-cancer effects on HeLa cells but did not influence cell viability or apoptosis of hDFs and these different effects were supported by profiling of secretory proteins in both kinds of CM and intracellular signaling of HeLa cells and hDFs.

• Anti-cancer
• Conditioned medium
• Fibroblasts
• Hypoxia
• Mesenchymal stem cells

• Hypoxia
• Mesenchymal stem cells (MSC)
• Migration
• Stemness
• Wharton's jelly

The results from our recent study showed the presence of two distinct spheroid-forming mechanisms, i.e., spontaneous and mechanical. In this study, we focused on the spontaneously formed spheroids, and the character of spontaneously formed spheroids from mouse compact bone-derived cells (CBDCs) was explored. Cells from (C57BL/6J) mouse leg bones were isolated, and compact bone-derived cells were cultured after enzymatic digestion. Spontaneous spheroid formation was achieved on a culture plate with specific water contact angle as reported. The expression levels of embryonic stem cell markers were analyzed using immunofluorescence and quantitative reverse transcription polymerase chain reaction. Then, the cells from spheroids were induced into osteogenic and neurogenic lineages. The spontaneously formed spheroids from CBDCs were positive for ES cell markers such as SSEA1, Sox2, Oct4, and Nanog. Additionally, the expressions of fucosyltransferase 4/FUT4 (SSEA1), Sox2, and Nanog were significantly higher than those in monolayer cultured cells. The gene expression of mesenchymal stem cell markers was almost identical in both spheroids and monolayer-cultured cells, but the expression of Sca-1 was higher in spheroids. Spheroid-derived cells showed significantly higher osteogenic and neurogenic marker expression than monolayer-cultured cells after induction. Spontaneously formed spheroids expressed stem cell markers and showed enhanced osteogenic and neurogenic differentiation capabilities than cells from the conventional monolayer culture, which supports the superior stemness.

• Nanog
• OCT-4
• SSEA-4
• WJ-MSC
• iPS
• mesenchymal stem cells
• pluripotency

Variability among donors, non-standardized methods for isolation, and characterization contribute to mesenchymal stem/stromal cell (MSC) heterogeneity. Induced pluripotent stem cell (iPSCs)-derived MSCs would circumvent many of current issues and enable large-scale production of standardized cellular therapy. To explore differences between native MSCs (nMSCs) and iPSC-derived MSCs (iMSCs), we developed isogeneic lines from Wharton’s jelly (WJ) from the umbilical cords of two donors (#12 and #13) under xeno-free conditions. Next, we reprogrammed them into iPSCs (iPSC12 and iPSC13) and subsequently differentiated them back into iMSCs (iMSC12 and iMSC13) using two different protocols, which we named ARG and TEX. We assessed their differentiation capability, transcriptome, immunomodulatory potential, and interferon-γ (IFNG)-induced changes in metabolome. Our data demonstrated that although both differentiation protocols yield iMSCs similar to their parental nMSCs, there are substantial differences. The ARG protocol resulted in iMSCs with a strong immunomodulatory potential and lower plasticity and proliferation rate, whereas the TEX protocol raised iMSCs with a higher proliferation rate, better differentiation potential, though weak immunomodulatory response. Our data suggest that, following a careful selection and screening of donors, nMSCs from umbilical’s cord WJ can be easily reprogrammed into iPSCs, providing an unlimited source of material for differentiation into iMSCs. However, the differentiation protocol should be chosen depending on their clinical use.

The key hallmark of stem cells is their ability to self-renew while keeping a differentiation potential. Intrinsic and extrinsic cell factors may contribute to a decline in these stem cell properties, and this is of the most importance when culturing them. One of these factors is oxygen concentration, which has been closely linked to the maintenance of stemness. The widely used environmental 21% O₂ concentration represents a hyperoxic non-physiological condition, which can impair stem cell behaviour by many mechanisms. The goal of this review is to understand these mechanisms underlying the oxygen signalling pathways and their negatively-associated consequences. This may provide a rationale for culturing stem cells under physiological oxygen concentration for stem cell therapy success, in the field of tissue engineering and regenerative medicine.

• aging
• environmental oxygen concentration
• physiological oxygen concentration
• physioxia
• redox
• senescence

• Adult mesenchymal stem cells
• Experimental cancer cytotherapy
• Gene delivery vehicles
• Tumor microenvironment
• Umbilical cord matrix stem cells
• Wharton’s jelly

• Notch
• Notch1
• Notch2
• Sox2
• cellular therapy
• flow cytometry
• neural stem cell
• neurosphere

• Animals
• Biomarkers/metabolism
• Cell Differentiation/physiology
• Cells, Cultured
• Flow Cytometry
• Gene Expression Regulation
• Green Fluorescent Proteins/genetics
• Humans
• Mice
• Mice, Transgenic
• Neural Stem Cells/cytology
• Neural Stem Cells/metabolism
• Receptor, Notch1/genetics
• Receptor, Notch1/metabolism
• Receptor, Notch2/genetics
• Receptor, Notch2/metabolism
• SOXB1 Transcription Factors/genetics
• SOXB1 Transcription Factors/metabolism

• Hypoxia
• Mesenchymal stem cell
• Proliferation
• Rat

Existing experimental data have shown hypoxia to be an important factor affecting the proliferation of mesenchymal stromal cells (MSCs), but the contrasting observations made at various hypoxic levels raise the questions of whether hypoxia accelerates proliferation, and how. On the other hand, in order to meet the increasing demand of MSCs, an optimised bioreactor control strategy is needed to enhance in vitro production.

A comprehensive, single-cell mathematical model has been constructed in this work, which combines cellular oxygen sensing with hypoxia-mediated cell cycle progression to predict cell cycle commitment as a proxy to proliferation rate. With oxygen levels defined for in vitro cell culture, the model predicts enhanced proliferation under intermediate (2–8%) and mild (8–15%) hypoxia and cell quiescence under severe (< 2%) hypoxia. Global sensitivity analysis and quasi-Monte Carlo simulation revealed that within a certain range (+/− 100%), model parameters affect (with varying significance) the minimum commitment time, but the existence of a range of optimal oxygen tension could be preserved with the hypothesized effects of Hif2α and reactive oxygen species (ROS). It appears that Hif2α counteracts Hif1α and ROS-mediated protein deactivation under intermediate hypoxia and normoxia (20%), respectively, to regulate the response of cell cycle commitment to oxygen tension.

Overall, this modelling study offered an integrative framework to capture several interacting mechanisms and allowed in silico analysis of their individual and collective roles in shaping the hypoxia-mediated commitment to cell cycle. The model offers a starting point to the establishment of a suitable mechanism that can satisfactorily explain the different existing experimental observations from different studies, and warrants future extension and dedicated experimental validation to eventually support bioreactor optimisation.

The online version of this article (10.1186/s12918-018-0560-3) contains supplementary material, which is available to authorized users.

• Cell cycle commitment
• Global sensitivity analysis
• HIF
• Hypoxia
• Intracellular modelling
• Mesenchymal stromal cells
• ROS

Adult stem cell-based therapeutic approaches for tissue regeneration have been proposed for several years. However, adult stem cells are usually limited in number and difficult to be expanded in vitro, and they usually tend to quickly lose their potency with passages, as they differentiate and become senescent. Culturing stem cells under reduced oxygen tensions (below 21%) has been proposed as a tool to increase cell proliferation, but many studies reported opposite effects. In particular, cell response to hypoxia seems to be very stem cell type specific. Nonetheless, it is clear that a major role in this process is played by the hypoxia inducible factor (HIF), the master regulator of cell response to oxygen deprivation, which affects cell metabolism and differentiation. Herein, we report that a chemical activation of HIF in human tendon stem cells reduces their proliferation and inhibits their differentiation in a reversible and dose-dependent manner. These results support the notion that hypoxia, by activating HIF, plays a crucial role in preserving stem cells in an undifferentiated state in the “hypoxic niches” present in the tissue in which they reside before migrating in more oxygenated areas to heal a damaged tissue.

Regardless of enormous translational progress in stem cell clinical application, our knowledge about biological determinants of transplantation-related protection is still limited. In addition to adequate selection of the cell source well dedicated to a specific disease and optimal standardization of all other pre-transplant procedures, we have decided to focus more attention to the impact of culture time and environment itself on molecular properties and regenerative capacity of cell cultured in vitro. The aim of this investigation was to determine neuroprotection-linked cell phenotypic and functional changes that could spontaneously take place when freshly isolated Wharton’s jelly mesenchymal stem cell (WJ-MSC) undergo standard selection, growth, and spontaneous differentiation throughout passaging in vitro. For determining their neuroprotective potential, we used experimental model of human WJ-MSC co-culture with intact or oxygen-glucose-deprived (OGD) rat organotypic hippocampal culture (OHC). It has been shown that putative molecular mechanisms mediating regenerative interactions between WJ-MSC and OHC slices relies mainly on mesenchymal cell paracrine activity. Interestingly, it has been also found that the strongest protective effect is exerted by the co-culture with freshly isolated umbilical cord tissue fragments and by the first cohort of human mesenchymal stem cells (hMSCs) migrating out of these fragments (passage 0). Culturing of WJ-derived hMSC in well-controlled standard conditions under air atmosphere up to fourth passage caused unexpected decline of neuroprotective cell effectiveness toward OGD-OHC in the co-culture model. This further correlated with substantial changes in the WJ-MSC phenotype, profile of their paracrine activities as well as with the recipient tissue reaction evaluated by changes in the rat-specific neuroprotection-linked gene expression.

• Hippocampal organotypic slice culture
• Neuroprotection
• Secretom
• Stem cells
• Stromal cells
• Wharton jelly