Hypoxic preconditioning enhances mesenchymal stromal cell lung repair capacity

Cell-Based Biomaterials for Coronavirus Disease 2019 Prevention and Therapy

Coronavirus disease 2019 (COVID-19) continues to threaten human health, economic development, and national security. Although many vaccines and drugs have been explored to fight against the major pandemic, their efficacy and safety still need to be improved. Cell-based biomaterials, especially living cells, extracellular vesicles, and cell membranes, offer great potential in preventing and treating COVID-19 owing to their versatility and unique biological functions. In this review, the characteristics and functions of cell-based biomaterials and their biological applications in COVID-19 prevention and therapy are described. First the pathological features of COVID-19 are summarized, providing enlightenment on how to fight against COVID-19. Next, the classification, organization structure, characteristics, and functions of cell-based biomaterials are focused on. Finally, the progress of cell-based biomaterials in overcoming COVID-19 in different aspects, including the prevention of viral infection, inhibition of viral proliferation, anti-inflammation, tissue repair, and alleviation of lymphopenia are comprehensively described. At the end of this review, a look forward to the challenges of this aspect is presented.

Tissue-Oxygen-Adaptation of Bone Marrow-Derived Mesenchymal Stromal Cells Enhances Their Immunomodulatory and Pro-Angiogenic Capacity, Resulting in Accelerated Healing of Chemical Burns

Transplantation of mesenchymal stromal cells (MSCs) provides a powerful tool for the management of multiple tissue injuries. However, poor survival of exogenous cells at the site of injury is a major complication that impairs MSC therapeutic efficacy. It has been found that tissue-oxygen adaptation or hypoxic pre-conditioning of MSCs could improve the healing process. Here, we investigated the effect of low oxygen tension on the regenerative potential of bone-marrow MSCs. It turned out that incubation of MSCs under a 5% oxygen atmosphere resulted in increased proliferative activity and enhanced expression of multiple cytokines and growth factors. Conditioned growth medium from low-oxygen-adapted MSCs modulated the pro-inflammatory activity of LPS-activated macrophages and stimulated tube formation by endotheliocytes to a much higher extent than conditioned medium from MSCs cultured in a 21% oxygen atmosphere. Moreover, we examined the regenerative potential of tissue-oxygen-adapted and normoxic MSCs in an alkali-burn injury model on mice. It has been revealed that tissue-oxygen adaptation of MSCs accelerated wound re-epithelialization and improved the tissue histology of the healed wounds in comparison with normoxic MSC-treated and non-treated wounds. Overall, this study suggests that MSC adaptation to 'physiological hypoxia' could be a promising approach for facilitating skin injuries, including chemical burns.

Fenoldopam Mesylate Enhances the Survival of Mesenchymal Stem Cells Under Oxidative Stress and Increases the Therapeutic Function in Acute Kidney Injury

Mesenchymal stem cells (MSCs) have gained interest as an alternative therapeutic option for renal diseases, including acute kidney injury (AKI). However, their use is often limited owing to low survival rates in vivo. Fenoldopam mesylate (FD) is a selective dopamine D1 receptor agonist with antioxidative and anti-apoptotic roles. Herein, we investigated whether FD can enhance the survival of MSCs undergoing oxidative stress in vitro. In addition, the therapeutic effect of MSCs and FD-treated MSCs (FD-MSCs) was compared in a mouse model of AKI induced by cisplatin. The survival of MSCs under oxidative stress was augmented by FD treatment. FD induced the phosphorylation of cAMP response element-binding protein and AKT, contributing to enhanced growth compared with untreated MSCs. The expression of nuclear factor erythroid-2-related factor 2 (NRF2) and heme oxygenase-1 was increased by FD treatment, and nuclear translocation of NRF2 was found exclusively in FD-MSCs. FD downregulated BAX expression, increased the mitochondrial membrane potential, reduced reactive oxygen species generation, and decreased the apoptotic death of MSCs induced by oxidative stress. Moreover, renal function and tubular injury were improved in FD-MSCs compared with non-treated MSCs. Furthermore, tubular injury, apoptosis, and macrophage infiltration, as well as the serum level of tumor necrosis factor-α were reduced, while tubular cell proliferation was markedly increased in FD-MSCs compared with MSCs. Our study demonstrated that FD increases the survivability of MSCs in an oxidative environment, and its use may be effective in preparing robust therapeutic MSCs.

Proteomics profile of mesenchymal stromal cells and extracellular vesicles in normoxic and hypoxic conditions

BACKGROUND AIMS

Although bone marrow-derived mesenchymal stromal cells (MSCs) have demonstrated success in pre-clinical studies, they have shown only mild therapeutic effects in clinical trials. Hypoxia pre-conditioning may optimize the performance of bone marrow-derived MSCs because it better reflects the physiological conditions of their origin. It is not known whether changes in the protein profile caused by hypoxia in MSCs can be extended to the extracellular vesicles (EVs) released from them. The aim of this study was to evaluate the proteomics profile of MSCs and their EVs under normoxic and hypoxic conditions.

METHODS

Bone marrow-derived MSCs were isolated from six healthy male Wistar rats. After achieving 80% confluence, MSCs were subjected to normoxia (MSC-Norm) (21% oxygen, 5% carbon dioxide, 74% nitrogen) or hypoxia (MSC-Hyp) (1% oxygen, 5% carbon dioxide, 94% nitrogen) for 48 h. Cell viability and oxygen consumption rate were assessed. EVs were extracted from MSCs for each condition (EV-Norm and EV-Hyp) by ultracentrifugation. Total proteins were isolated from MSCs and EVs and prepared for mass spectrometry. EVs were characterized by nanoparticle tracking analysis. Proteomics data were analyzed by PatternLab 4.0, Search Tool for the Retrieval of Interacting Genes/Proteins, Gene Ontology, MetaboAnalyst and Reactome software.

RESULTS

Cell viability was higher in MSC-Hyp than MSC-Norm (P = 0.007). Basal respiration (P = 0.001), proton leak (P = 0.004) and maximal respiration (P = 0.014) were lower in MSC-Hyp than MSC-Norm, and no changes in adenosine triphosphate-linked and residual respiration were observed. The authors detected 2177 proteins in MSC-Hyp and MSC-Norm, of which 147 were identified in only MSC-Hyp and 512 were identified in only MSC-Norm. Furthermore, 718 proteins were identified in EV-Hyp and EV-Norm, of which 293 were detected in only EV-Hyp and 30 were detected in only EV-Norm. Both MSC-Hyp and EV-Hyp showed enrichment of pathways and biological processes related to glycolysis, the immune system and extracellular matrix organization.

CONCLUSIONS

MSCs subjected to hypoxia showed changes in their survival and metabolic activity. In addition, MSCs under hypoxia released more EVs, and their content was related to expression of regulatory proteins of the immune system and extracellular matrix organization. Because of the upregulation of proteins involved in glycolysis, gluconeogenesis and glucose uptake during hypoxia, production of reactive oxygen species and expression of immunosuppressive properties may be affected.

Characterization of Extracellular Vesicles from Preconditioned Human Adipose-Derived Stromal/Stem Cells

Cell-free therapy using extracellular vesicles (EVs) from adipose-derived mesenchymal stromal/stem cells (ASCs) seems to be a safe and effective therapeutic option to support tissue and organ regeneration. The application of EVs requires particles with a maximum regenerative capability and hypoxic culture conditions as an in vitro preconditioning regimen has been shown to alter the molecular composition of released EVs. Nevertheless, the EV cargo after hypoxic preconditioning has not yet been comprehensively examined. The aim of the present study was the characterization of EVs from hypoxic preconditioned ASCs. We investigated the EV proteome and their effects on renal tubular epithelial cells in vitro. While no effect of hypoxia was observed on the number of released EVs and their protein content, the cargo of the proteins was altered. Proteomic analysis showed 41 increased or decreased proteins, 11 in a statistically significant manner. Furthermore, the uptake of EVs in epithelial cells and a positive effect on oxidative stress in vitro were observed. In conclusion, culture of ASCs under hypoxic conditions was demonstrated to be a promising in vitro preconditioning regimen, which alters the protein cargo and increases the anti-oxidative potential of EVs. These properties may provide new potential therapeutic options for regenerative medicine.

Effects of mesenchymal stromal cell-conditioned media on measures of lung structure and function: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Lung disease is a leading cause of morbidity and mortality. A breach in the lung alveolar-epithelial barrier and impairment in lung function are hallmarks of acute and chronic pulmonary illness. This review is part two of our previous work. In part 1, we demonstrated that CdM is as effective as MSCs in modulating inflammation. Herein, we investigated the effects of mesenchymal stromal cell (MSC)-conditioned media (CdM) on (i) lung architecture/function in animal models mimicking human lung disease, and (ii) performed a head-to-head comparison of CdM to MSCs.

METHODS

Adhering to the animal Systematic Review Centre for Laboratory animal Experimentation protocol, we conducted a search of English articles in five medical databases. Two independent investigators collected information regarding lung: alveolarization, vasculogenesis, permeability, histologic injury, compliance, and measures of right ventricular hypertrophy and right pulmonary pressure. Meta-analysis was performed to generate random effect size using standardized mean difference with 95% confidence interval.

RESULTS

A total of 29 studies met inclusion. Lung diseases included bronchopulmonary dysplasia, asthma, pulmonary hypertension, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis. CdM improved all measures of lung structure and function. Moreover, no statistical difference was observed in any of the lung measures between MSCs and CdM.

CONCLUSIONS

In this meta-analysis of animal models recapitulating human lung disease, CdM improved lung structure and function and had an effect size comparable to MSCs.

Natural Compounds as a Strategy to Optimize "In Vitro" Expansion of Stem Cells

The efficient use of stem cells for transplantation is often limited by the relatively low number of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, which is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different types of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro.

Mesenchymal stem cell therapy for the treatment of inflammatory diseases: Challenges, opportunities, and future perspectives

Mesenchymal stem cells (MSCs) are promising alternative agents for the treatment of inflammatory disorders due to their immunomodulatory functions, and several clinical trials on MSC-based products are currently being conducted. In this review, we discuss recent progress made on the use of MSCs as immunomodulatory agents, developmental challenges posed by MSC-based therapy, and the strategies being used to overcome these challenges. In this context, current understanding of the mechanisms responsible for MSC interactions with the immune system and the molecular responses of MSCs to inflammatory signals are discussed. The immunosuppressive activities of MSCs are initiated by cell-to-cell contact and the release of immuno-regulatory molecules. By doing so, MSCs can inhibit the proliferation and function of T cells, natural killer cells, B cells, and dendritic cells, and can also increase the proliferation of regulatory T cells. However, various problems, such as low transplanted cell viability, poor homing and engraftment into injured tissues, MSC heterogeneity, and lack of adequate information on optimum MSC doses impede clinical applications. On the other hand, it has been shown that the immunomodulatory activities and viabilities of MSCs might be enhanced by 3D-cultured systems, genetic modifications, preconditioning, and targeted-delivery.

Comparison of Preterm and Term Wharton's Jelly-Derived Mesenchymal Stem Cell Properties in Different Oxygen Tensions

Mesenchymal stem cells (MSCs) have shown promise as therapeutic agents in treating morbidities associated with premature birth. MSCs derived from the human umbilical cord are easy to isolate and have low immunogenicity and a robust ability to secrete paracrine factors. To date, there are no studies evaluating preterm versus term umbilical cord tissue-derived MSCs. Therefore, our aim was twofold: (1) to compare stem cell properties in preterm versus term MSCs and (2) to examine the impact of oxygen tension on stem cell behavior. Umbilical cord tissue was obtained from 5 preterm and 5 term neonates. The cells were isolated and characterized as MSCs in accordance with the International Society for Cellular Therapy. We exposed MSCs to different oxygen tensions to examine the impact of environmental factors on cell performance. We studied the following stem cell properties: (i) motility, (ii) proliferation, (iii) senescence, (iv) cell viability, (v) colony-forming unit efficiency, and (vi) inflammatory cytokine expression. Under normoxia (21% O2), cells from preterm and term infants had similar properties. Under hypoxic conditions (1% O2), term MSCs had better cell proliferation; however, cells exposed to hyperoxia (90% O2) had the slowest motility and lowest cell viability (p < 0.05). There was no difference in the expression of senescence or cytokine expression between the groups. The term cells demonstrated more colony-forming efficiency than the preterm cells. In sum, our preliminary findings suggest that MSCs derived from term and preterm umbilical cords have similar characteristics, offering the potential of future autologous/allogeneic MSC transplants in neonates.

Hypoxic conditioning in blood vessels and smooth muscle tissues: effects on function, mechanisms, and unknowns

Hypoxic preconditioning, the protective effect of brief, intermittent hypoxic or ischemic episodes on subsequent more severe hypoxic episodes, has been known for 30 yr from studies on cardiac muscle. The concept of hypoxic preconditioning has expanded; excitingly, organs beyond the heart, including the brain, liver, and kidney, also benefit. Preconditioning of vascular and visceral smooth muscles has received less attention despite their obvious importance to health. In addition, there has been no attempt to synthesize the literature in this field. Therefore, in addition to overviewing the current understanding of hypoxic conditioning, in the present review, we consider the role of blood vessels in conditioning and explore evidence for conditioning in other smooth muscles. Where possible, we have distinguished effects on myocytes from other cell types in the visceral organs. We found evidence of a pivotal role for blood vessels in conditioning and for conditioning in other smooth muscle, including the bladder, vascular myocytes, and gastrointestinal tract, and a novel response in the uterus of a hypoxic-induced force increase, which helps maintain contractions during labor. To date, however, there are insufficient data to provide a comprehensive or unifying mechanism for smooth muscles or visceral organs and the effects of conditioning on their function. This also means that no firm conclusions can be drawn as to how differences between smooth muscles in metabolic and contractile activity may contribute to conditioning. Therefore, we have suggested what may be general mechanisms of conditioning occurring in all smooth muscles and tabulated tissue-specific mechanistic findings and suggested ideas for further progress.

Preconditioning influences mesenchymal stem cell properties in vitro and in vivo

Various diseases and toxic factors easily impair cellular and organic functions in mammals. Organ transplantation is used to rescue organ function, but is limited by scarce resources. Mesenchymal stem cell (MSC)-based therapy carries promising potential in regenerative medicine because of the self-renewal and multilineage potency of MSCs; however, MSCs may lose biological functions after isolation and cultivation for a long time in vitro. Moreover, after they are injected in vivo and migrate into the damaged tissues or organs, they encounter a harsh environment coupled with death signals due to the inadequate tensegrity structure between the cells and matrix. Preconditioning, genetic modification and optimization of MSC culture conditions are key strategies to improve MSC functions in vitro and in vivo, and all of these procedures will contribute to improving MSC transplantation efficacy in tissue engineering and regenerative medicine. Preconditioning with various physical, chemical and biological factors is possible to preserve the stemness of MSCs for further application in studies and clinical tests. In this review, we mainly focus on preconditioning and the corresponding mechanisms for improving MSC activities in vitro and in vivo; we provide a glimpse into the promotion of MSC-based cell therapy development for regenerative medicine. As a promising consequence, MSC transplantation can be applied for the treatment of some terminal diseases and can prolong the survival time of patients in the near future.

Hypoxia-Preconditioned Human Umbilical Vein Endothelial Cells Protect Against Neurovascular Damage After Hypoxic Ischemia in Neonatal Brain

Therapy targeting the neurovascular unit may provide effective neuroprotection against neonatal hypoxia-ischemia (HI). We hypothesized that the peripheral injection of hypoxia-preconditioned human umbilical vein endothelial cells (HUVECs) following HI protects against neurovascular damage and provides long-term neuroprotection in a postpartum (P) day-7 rat pup model. Compared with normoxic HUVECs, hypoxic HUVECs showed enhanced migration and angiogenesis in vitro and had augmented migration effects into the brain when administered intraperitoneally in vivo after HI. Moreover, 24 and 72 h post-HI, the hypoxic HUVECs group but not the normoxic HUVECs or culture-medium groups had significantly higher preservation of microvessels and neurons, and attenuation of blood-brain barrier damage than the normal-saline group. Compared to control or normal-saline groups, only the hypoxic HUVECs group had no impaired foot steps and showed a significant reduction of brain area loss at P42. Next-generation sequencing showed hypoxia-induced upregulation and downregulation of 209 and 215 genes in HUVECs, respectively. Upstream regulator analysis by ingenuity pathway analysis (IPA) identified hypoxia-inducible factor 1-alpha as the key predicted activated transcription regulator. After hypoxia, 12 genes (ADAMTS1, EFNA1, HIF1A, LOX, MEOX2, SELE, VEGFA, VEGFC, CX3CL1, HMMR, SDC, and SERPINE) associated with migration and/or angiogenesis were regulated in HUVECs. In addition, 6 genes (VEGFA, VEGFC, NTN4, TGFA, SERPINE1, and CX3CL1) involved in the survival of endothelial and neuronal cells were also markedly altered in hypoxic HUVECs. Thus, cell therapy by using hypoxic HUVECs that enhance migration and neurovascular protection may provide an effective therapeutic strategy for treating neonatal asphyxia.

Into the eyes of bone marrow-derived mesenchymal stem cells therapy for myocardial infarction and other diseases

Applications of bone marrow-derived mesenchymal stem cells (BM-MSCs) have been documented for diseases occur in the sports system, the central nervous system, the cardiovascular system etc. However, poor viability of donor stem cells after transplantation limits their therapeutic efficiency. Although the autophagy theory has been reported, the underlying mechanisms are still poorly understood. Isolation and culture methods of mesenchymal stem cells are currently concentrate on four ways. Overall, BM-MSCs have both important research significance and clinical application value in cell replacement therapy, gene therapy and reconstruction of tissues as well as organs especially for myocardial infarction (MI). In this article, we review the biological characteristics of BM-MSCs and its research progress especially in MI.

Formation of spheroids by dental pulp cells in the presence of hypoxia and hypoxia mimetic agents

AIM

To evaluate the impact of hypoxia and hypoxia mimetic agents (HMA) on the formation and activity of spheroids by dental pulp cells (DPC).

METHODOLOGY

DPC on agarose-coated plates were treated with hypoxia and the HMA dimethyloxallyl glycine (DMOG), desferrioxamine (DFO) and L-mimosine (L-MIM). Images of spheroids were taken directly after seeding and at 6 h and 24 h. Spheroid sizes were quantified by area measurement with ImageJ software. Viability was assessed with Live-Dead staining, MTT and resazurin-based toxicity assay. Production of VEGF, IL-8 and SDF-1 was evaluated using immunoassays. Data were analysed using Kruskal-Wallis test and post hoc Mann-Whitney U-test.

RESULTS

DPC formed spheroids in the presence of hypoxia, HMA and combined treatment with hypoxia and HMA. No pronounced difference in spheroid size was found in the groups treated with hypoxia, DMOG, DFO, L-MIM and the combination of hypoxia and the HMA relative to their normoxic controls (P > 0.05). Spheroids appeared vital in Live-Dead and MTT staining and the resazurin-based toxicity assay. Evaluation of protein production with immunoassays revealed significantly enhanced levels of VEGF and IL-8 (P < 0.05), but there was no significant effect on SDF-1 production (P > 0.05). Treatment with a combination of hypoxia and HMA did not further boost VEGF and IL-8 production (P > 0.05).

CONCLUSIONS

Pre-conditioning with hypoxia and HMA increased the pro-angiogenic capacity of spheroids whilst not interfering with their formation. Pre-clinical studies will reveal whether pre-conditioning of spheroids with hypoxia and HMA can effectively improve the efficiency of cell transplantation approaches for regenerative endodontics.

Autophagy mediates the beneficial effect of hypoxic preconditioning on bone marrow mesenchymal stem cells for the therapy of myocardial infarction

Background

Stem cell therapy has emerged as a promising therapeutic strategy for myocardial infarction (MI). However, the poor viability of transplanted stem cells hampers their therapeutic efficacy. Hypoxic preconditioning (HPC) can effectively promote the survival of stem cells. The aim of this study was to investigate whether HPC improved the functional survival of bone marrow mesenchymal stem cells (BM-MSCs) and increased their cardiac protective effect.

Methods

BM-MSCs, isolated from Tg(Fluc-egfp) mice which constitutively express both firefly luciferase (Fluc) and enhanced green fluorescent protein (eGFP), were preconditioned with HPC (1% O₂) for 12 h, 24 h, 36 h, and 48 h, respectively, followed by 24 h of hypoxia and serum deprivation (H/SD) injury.

Results

HPC dose-dependently increased the autophagy in BM-MSCs. However, the protective effects of HPC for 24 h are most pronounced. Moreover, hypoxic preconditioned BM-MSCs (^HPCMSCs) and nonhypoxic preconditioned BM-MSCs (^NPCMSCs) were transplanted into infarcted hearts. Longitudinal in vivo bioluminescence imaging (BLI) and immunofluorescent staining revealed that HPC enhanced the survival of engrafted BM-MSCs. Furthermore, ^HPCMSCs significantly reduced fibrosis, decreased apoptotic cardiomyocytes, and preserved heart function. However, the beneficial effect of HPC was abolished by autophagy inhibition with 3-methyladenine (3-MA) and Atg7siRNA.

Conclusion

This study demonstrates that HPC may improve the functional survival and the therapeutic efficiencies of engrafted BM-MSCs, at least in part through autophagy regulation. Hypoxic preconditioning may serve as a promising strategy for optimizing cell-based cardiac regenerative therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0543-0) contains supplementary material, which is available to authorized users.

Bone marrow mesenchymal stem cells inhibited bleomycin-induced lung fibrosis

The present study was performed to evaluate the protective effect of bone marrow mesenchymal stem cells (BMSCs), TLR2-silencing BMSCs (BMSC^TLR2−/−), on bleomycin (BLM)-induced lung fibrosis and elucidate the critical role of TLR2 during the process.