Efficient Generation of Neural Stem Cell-Like Cells from Rat Adipose Derived Stem Cells After Lentiviral Transduction with Green Fluorescent Protein

Neuroprotective effects of adipose‐derived stem cells on ferrous sulfate‐induced neurotoxicity

Background:

Ferrous ion, a degradation product of hematomas, induces inflammatory reactions and other secondary injuries after intracerebral hemorrhage (ICH). Our study aimed to investigate the specific neuroprotective mechanism of adipose‐derived stem cells (ADSCs) on ferrous ion‐induced neural injury in vitro.

Methods:

ADSCs were co‐cultured with primary cortical neurons in a transwell system treated with ferrous sulfate to generate an in vitro ICH model. ADSCs and cortical neurons were cultured in the upper and lower chambers, respectively. Neuron apoptosis was determined by flow cytometry. The levels of insulin‐like growth factor‐1 (IGF‐1), malondialdehyde (MDA) and nitric oxide synthase (NOS) activity in neuron culture medium were detected with commercial kits. In neurons, protein expression in phosphatidylinositol‐3‐kinase (PI3K)/protein kinase B (Akt) signaling pathway, nuclear factor erythroid 2‐related factor 2 (Nrf2)/heme oxygenase‐1 (HO‐1) signaling pathway and apoptosis‐related proteins were detected by western blot.

Results:

ADSCs attenuated neural apoptosis, reduced MDA levels and NOS activity induced by ferrous sulfate. In neurons, IGF‐1 was increased, as were p‐PI3K, p‐Akt, Nrf2, HO‐1, and Bcl‐2 while cleaved caspase 3 was down‐regulated.

Conclusions:

ADSCs exert neuroprotective effects against ferrous iron‐induced neuronal damage by secreting IGF‐1 and increasing the levels of Akt‐dependent Nrf2/ARE signaling pathway.

Overexpression of CX3CR1 in Adipose-Derived Stem Cells Promotes Cell Migration and Functional Recovery After Experimental Intracerebral Hemorrhage

Stem cell therapy has emerged as a new promising therapeutic strategy for intracerebral hemorrhage (ICH). However, the efficiency of stem cell therapy is partially limited by low retention and engraftment of the delivered cells. Therefore, it’s necessary to improve the migration ability of stem cells to the injured area in order to save the costs and duration of cell preparation. This study aimed to investigate whether overexpression of CX3CR1, the specific receptor of chemokine fractalkine (FKN), in adipose-derived stem cells (ADSCs) can stimulate the cell migration to the injured area in the brain, improve functional recovery and protect against cell death following experimental ICH. ADSCs were isolated from subcutaneous adipose tissues of rats. ICH was induced by means of an injection of collagenase type VII. ELISA showed that the expression levels of fractalkine/FKN were increased at early time points, with a peak at day 3 after ICH. And it was found that different passages of ADSCs could express the chemokine receptor CX3CR1. Besides, the chemotactic movements of ADSCs toward fractalkine have been verified by transwell migration assay. ADSCs overexpressing CX3CR1 were established through lentivirus transfection. We found that after overexpression of CX3CR1 receptor, the migration ability of ADSCs was increased both in vitro and in vivo. In addition, reduced cell death and improved sensory and motor functions were seen in the mice ICH model. Thus, ADSCs overexpression CX3CR1 might be taken as a promising therapeutic strategy for the treatment of ICH.

Adipose-derived mesenchymal stem cells stereotactic transplantation alleviate brain edema from intracerebral hemorrhage

Adipose-derived mesenchymal stromal cells (ADSCs) exhibited high potential in tissue repair and regeneration, and it has been proved that ADSCs could protect brain cells from apoptosis and maintaining blood-brain barrier stability after cerebral vascular disease. In this study, we evaluated the therapeutic potential and mechanism of ADSCs stereotactic transplantation in intracerebral hemorrhage (ICH) mice model and hemin-treated astrocytes. Mice were divided into three groups: sham group, ICH + PBS group, and ICH + ADSC group. Mice in ICH + ADSC group received ADSCs cell suspension stereotactic transplantation into the area beside the bleeding region. Astrocytes were divided into three groups: control group, hemin group, and hemin + ADSC group. Astrocytes in hemin + ADSC group were cultured in ADSCs-astrocyte no-contact coculture system and treated with 30 μM hemin solution. The results showed that ADSCs stereotactic transplantation improved functional outcomes and reduced cell apoptosis after ICH. Moreover, ADSCs stereotactic transplantation could alleviate brain edema and inflammation and AQP4 protein expression contributed to the alleviation of brain edema. In addition, mitogen-activated protein kinase (MAPK) pathways, including p38/MAPK pathway and c-Jun N-terminal kinase pathway, were involved in AQP4 modulation by ADSCs transplantation in ICH. In conclusion, ADSCs transplantation could alleviate the nervous tissue injury, reduce cell apoptosis, and relieve brain edema in ICH. And the edema regulation effect of ADSCs transplantation is associated with inhibition of inflammation and AQP4 protein expression.

Upregulated TSG-6 Expression in ADSCs Inhibits the BV2 Microglia-Mediated Inflammatory Response

Objectives

The microglial cells are immune surveillance cells in the central nervous system and can be activated during neurological disorders. Adipose-derived stem cells (ADSCs) were reported to inhibit the inflammatory response in microglia by secreting proteins like tumor necrosis factor-inducible gene 6 protein (TSG-6). We aim to explore the mechanisms and the associated microRNAs.

Methods

ADSCs were cultured and TSG-6 expression was evaluated. ADSCs were cocultured with lipopolysaccharide- (LPS-) induced BV2 microglia and the supernatant was harvested for detecting cytokines. The total RNA was extracted and sequenced by high-throughput sequencing. MicroRNA profiles were compared between two treatment groups of ADSCs. A comprehensive bioinformatics analysis and confirmation experiments were performed to identify the microRNAs targeting at TSG-6.

Results

We found that ADSCs could secrete TSG-6 to inhibit the proinflammatory cytokines, including interleukin-1 beta and interleukin-6, and tumor necrosis factor alpha (TNFα), produced by LPS-induced microglia-mediated inflammatory response. Bioinformatics analysis showed a total of 35 microRNAs differentially expressed between the two groups of ADSCs, and miR-214-5p was identified as a regulator of TSG-6 mRNA.

Conclusion

Following a treatment with TNFα, ADSCs can regulate the inflammatory response in LPS-activated BV2 microglia by upregulating TSG-6 expression, which itself is under the negative control of miR-214-5p.

Molecular Mechanisms of Transdifferentiation of Adipose-Derived Stem Cells into Neural Cells: Current Status and Perspectives

Neurological diseases can severely compromise both physical and psychological health. Recently, adult mesenchymal stem cell- (MSC-) based cell transplantation has become a potential therapeutic strategy. However, most studies related to the transdifferentiation of MSCs into neural cells have had disappointing outcomes. Better understanding of the mechanisms underlying MSC transdifferentiation is necessary to make adult stem cells more applicable to treating neurological diseases. Several studies have focused on adipose-derived stromal/stem cell (ADSC) transdifferentiation. The purpose of this review is to outline the molecular characterization of ADSCs, to describe the methods for inducing ADSC transdifferentiation, and to examine factors influencing transdifferentiation, including transcription factors, epigenetics, and signaling pathways. Exploring and understanding the mechanisms are a precondition for developing and applying novel cell therapies.

Cell tracking, survival, and differentiation capacity of adipose-derived stem cells after engraftment in rat tissue

Adipose tissue is an important source of adipose derived stem cells (ADSCs). These cells have the potential of being used for certain therapies, in which the main objective is to recover the function of a tissue/organ affected by a disease. In order to contribute to repair of the tissue, these cells should be able to survive and carry out their functions in unfavorable conditions after being transplanted. This process requires a better understanding of the biology involved: such as the time cells remain in the implant site, how long they stay there, and whether or not they differentiate into host tissue cells. This report focuses on these questions. ADSC were injected into three different tissues (substantia nigra, ventricle, liver) and they were tracked in vivo with a dual GFP-Luc reporter system. The results show that ADSCs were able to survive up to 4 months after the engraftment and some of them started showing resident cell tissue phenotype. These results demonstrate their long-term capacity of survival and differentiation when injected in vivo.

Hydrogel scaffolds for differentiation of adipose-derived stem cells

Natural extracellular matrices (ECMs) have been widely used as a support for the adhesion, migration, differentiation, and proliferation of adipose-derived stem cells (ADSCs). However, poor mechanical behavior and unpredictable biodegradation properties of natural ECMs considerably limit their potential for bioapplications and raise the need for different, synthetic scaffolds. Hydrogels are regarded as the most promising alternative materials as a consequence of their excellent swelling properties and their resemblance to soft tissues. A variety of strategies have been applied to create synthetic biomimetic hydrogels, and their biophysical and biochemical properties have been modulated to be suitable for cell differentiation. In this review, we first give an overview of common methods for hydrogel preparation with a focus on those strategies that provide potential advantages for ADSC encapsulation, before summarizing the physical properties of hydrogel scaffolds that can act as biological cues. Finally, the challenges in the preparation and application of hydrogels with ADSCs are explored and the perspectives are proposed for the next generation of scaffolds.

Transplantation of human adipose tissue-derived stem cells for repair of injured spiral ganglion neurons in deaf guinea pigs

Excessive noise, ototoxic drugs, infections, autoimmune diseases, and aging can cause loss of spiral ganglion neurons, leading to permanent sensorineural hearing loss in mammals. Stem cells have been confirmed to be able to differentiate into spiral ganglion neurons. Little has been reported on adipose tissue-derived stem cells (ADSCs) for repair of injured spiral ganglion neurons. In this study, we hypothesized that transplantation of neural induced-human ADSCs (NI-hADSCs) can repair the injured spiral ganglion neurons in guinea pigs with neomycin-induced sensorineural hearing loss. NI-hADSCs were induced with culture medium containing basic fibroblast growth factor and forskolin and then injected to the injured cochleae. Guinea pigs that received injection of Hanks' balanced salt solution into the cochleae were used as controls. Hematoxylin-eosin staining showed that at 8 weeks after cell transplantation, the number of surviving spiral ganglion neurons in the cell transplantation group was significantly increased than that in the control group. Also at 8 weeks after cell transplantation, immunohistochemical staining showed that a greater number of NI-hADSCs in the spiral ganglions were detected in the cell transplantation group than in the control group, and these NI-hADSCs expressed neuronal markers neurofilament protein and microtubule-associated protein 2. Within 8 weeks after cell transplantation, the guinea pigs in the cell transplantation group had a gradually decreased auditory brainstem response threshold, while those in the control group had almost no response to 80 dB of clicks or pure tone burst. These findings suggest that a large amount of NI-hADSCs migrated to the spiral ganglions, survived for a period of time, repaired the injured spiral ganglion cells, and thereby contributed to the recovery of sensorineural hearing loss in guinea pigs.

A Modified Approach to Inducing Bone Marrow Stromal Cells to Differentiate into Cells with Mature Schwann Cell Phenotypes

Marrow stromal cells (MSCs) can be induced to differentiate into Schwann-like cells under classical induction conditions. However, cells derived from this method are unstable, exhibiting a low neurotrophin expression level after the induction conditions are removed. In Schwann cell (SC) culture, progesterone (PROG) enhances neurotrophic synthesis and myelination, specifically regulating the expression of the myelin protein zero (P0)- and peripheral myelin protein 22 (PMP22)-encoding genes by acting in concert or in synergy with insulin and glucocorticoids (GLUCs). In the present study, we investigated whether combined PROG, GLUC, and insulin therapy induced MSCs to differentiate into modified SC-like cells with phenotypes similar to those of mature SCs. After being cultured for 2 weeks in modified differentiation medium, the modified SC-like cells showed increased expression of P0 and PMP22. In addition, morphological and phenotypic characterizations were conducted over a period of over 2 weeks, and functional characteristics persisted for more than 3 weeks after the induction reagents were withdrawn. The transplantation of green fluorescent protein-labeled, modified SC-like cells into transected sciatic nerves with a 10-mm gap significantly increased the proliferation of the original SCs and improved axon regeneration and myelination compared with original BM-SCs. Immunostaining for P0 revealed that more of the transplanted modified SC-like cells retained the phenotypic characteristics of SCs. Taken together, these results reveal that the combined application of PROG, GLUC, and insulin induces MSCs to differentiate into cells with phenotypic, molecular, and functional properties of mature SCs.

Generation of neurospheres from human adipose-derived stem cells

Transplantation of neural stem cells (NSCs) to treat neurodegenerative disease shows promise; however, the clinical application of NSCs is limited by the invasive procurement and ethical concerns. Adipose-derived stem cells (ADSCs) are a source of multipotent stem cells that can self-renew and differentiate into various kinds of cells; this study intends to generate neurospheres from human ADSCs by culturing ADSCs on uncoated culture flasks in serum-free neurobasal medium supplemented with B27, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF); the ADSCs-derived neurospheres were terminally differentiated after growth factor withdrawal. Expression of Nestin, NeuN, MAP2, and GFAP in ADSCs and terminally differentiated neurospheres was shown by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, and immunocytochemistry; cell proliferation in neurospheres was evaluated by cell cycle analyses, immunostaining, and flow cytometry. These data strongly support the conclusion that human ADSCs can successfully differentiate into neurospheres efficiently on uncoated culture flasks, which present similar molecular marker pattern and proliferative ability with NSCs derived from embryonic and adult brain tissues. Therefore, human ADSCs may be an ideal alternative source of stem cells for the treatment of neurodegenerative diseases.

Human adipose-derived stem cells accelerate the restoration of tensile strength of tendon and alleviate the progression of rotator cuff injury in a rat model

Adult stem cell therapy for the treatment of tendon injuries is a growing area of research. This study is aimed to investigate the efficacy of human adipose-derived stem cell (hADSC) injection on the tendon during its healing process in a rat model of rotator cuff injury. hADSCs were injected 3 days after collagenase-induced rotator cuff injuries in experimental groups, while the control group received saline as a placebo. Histological and biomechanical analyses were performed 7, 14, 21, and 28 days after collagenase injection. Compared to the control group, it was found that inflammatory cells were significantly decreased in the hADSC-treated group after collagenase injection for 7 and 14 days. In the hADSC-injected group, the fiber arrangement and tendon organization had also been improved. On the seventh day after collagenase injection, the load to failure of the hADSC-injected group (15.87 ± 2.20 N) was notably higher than that of the saline-injected group (11.20 ± 1.35 N). It is suggested that the tensile strength of the supraspinatus tendon was significantly enhanced. Local administration of hADSCs might have the possibility to restore the tensile strength and attenuate the progression of tendinitis. Taken together, these findings demonstrate that the recovery processes in damaged tendons can be facilitated architecturally and functionally after hADSC injection.

Collagen nanofibers facilitated presynaptic maturation in differentiated neurons from spinal-cord-derived neural stem cells through MAPK/ERK1/2-Synapsin I signaling pathway

Neural stem cells (NSCs) are deemed to be a potential cell therapy for brain and spinal cord reconstruction and regeneration following injury. In this study, we investigated the role of nanofibrous scaffolds on NSCs-derived neurons in the formation of neural networks. Miniature excitatory postsynaptic currents (mEPSCs) were recorded using the whole-cell patch clamp recording method after the spinal cord-derived NSCs were differentiated into neurons and cultured in vitro for 10-14 days. It was observed that the frequency of mEPSCs in the differentiated neurons cultured on both randomly oriented and aligned collagen nanofibrous scaffolds was higher than that on the collagen-coated control and can be inhibited by an ERK inhibitor (PD98059), indicating that the collagen nanofibers affected the maturation of the synapses from presynaptic sites via the MAPK/ERK1/2 pathway. In addition, both of the collagen nanofibers increased the phosphorylation of Synapsin I and facilitated the interaction of p-ERK1/2 and p-Synapsin I. All these results suggested that the collagen nanofibrous scaffolds contributed to the presynaptic maturation via the ERK1/2-Synapsin I signaling pathway.