bFGF enhances the IGFs-mediated pluripotent and differentiation potentials in multipotent stem cells

CBX7 Rejuvenates Late Passage Dental Pulp Stem Cells by Maintaining Stemness and Pro-angiogenic Ability

BACKGROUND

Ever-growing tissue regeneration causes pressing need for large population of stem cells. However, extensive cell expansion eventually leads to impaired regenerative potentials. In this study, chromobox protein homolog 7 (CBX7) was overexpressed to rejuvenate late passage dental pulp stem cells (DPSCs-P9).

METHODS

The recruitment of copper ions (Cu2+)-activated hypoxia-inducible factor-1α (HIF-1α) to the CBX7 gene promoter was confirmed by chromatin immunoprecipitation assay. Functions subsequent to Cu2+-induced or recombinant overexpression of CBX7 on proliferation, multipotency, odontoblastic differentiation and angiogenesis were investigated in vitro, while murine subcutaneous transplantation model was used to further detect the effects of Cu2+-induced CBX7 overexpression in vivo.

RESULTS

Our data displayed that CBX7 overexpression maintain proliferation and multipotency of DPSCs-P9 almost as strong as those of DPSCs-P3. Both gene level of odontoblast-lineage markers and calcium precipitation were nearly the same between CBX7 overexpressed DPSCs-P9 and normal DPSCs-P3. Moreover, we also found upregulated expression of vascular endothelial growth factor in DPSCs-P9 with CBX7 overexpression, which increased the number of capillary-like structures and migrating co-cultured human umbilical vein endothelial cells as well. These findings indicate CBX7 as an effective factor to rejuvenate late passage stem cells insusceptible to cell expansion. Cu2+ has been proved to achieve CBX7 overexpression in DPSCs through the initiation of HIF-1α-CBX7 cascade. Under Cu2+ stimulation since P3, DPSCs-P9 exhibited ameliorated regenerative potential both in vitro and in vivo.

CONCLUSION

Long-term stimulation of Cu2+ to overexpress CBX7 could be a new strategy to manufacture large population of self-renewing stem cells.

TMEM45A Affects Proliferation, Apoptosis, Epithelial-Mesenchymal Transition, Migration, Invasion and Cisplatin Resistance of HPV-Positive Cervical Cancer Cell Lines

To investigate the effects of transmembrane protein 45A (TMEM45A) on biological characteristics and cisplatin (DDP) resistance of cervical cancer cells. TMEM45A in cervical cancer cells and normal cervical epithelial cells (HCerEpiC) were quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. HPV genotypes were identified by multiplex PCR. SiHa and HeLa cells were divided into Blank, shCTL, shTMEM45A-1, and shTMEM45A-2 groups, followed by Cell Counting Kit-8 (CCK-8), EdU, Annexin V-FITC/PI staining, Wound healing, and Transwell invasion assays, as well as qRT-PCR and Western blotting. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) was employed to evaluate the impact of TMEM45A shRNA on cisplatin-resistant cervical cancer cells (SiHa/DDP and HeLa/DDP). Compared with HcerEpic cell, cervical cancer cells exhibited the upregulation of TMEM45A expression, especially in HPV-positive cell lines (CaSki, SiHa, HeLa). TMEM45A shRNA suppressed the proliferation of SiHa and HeLa cells, arrested cells at the S phase, and promoted cell apoptosis. TMEM45A shRNA inhibited the epithelial-mesenchymal transition (EMT), invasion, migration of SiHa and HeLa cells, accompanying by the downregulated Vimentin and N-cadherin with the upregulated E-cadherin. Moreover, SiHa/DDP and HeLa/DDP had higher TMEM45A expression than their parental SiHa and HeLa cells, respectively. And inhibiting TMEM45A can reduce the IC50 of SiHa/DDP cells and HeLa/DDP cells to cisplatin. Silencing TMEM45A can inhibit cell proliferation, invasion, migration and EMT, regulate cell cycle distribution, promote cell apoptosis, and reverse cisplatin resistance of HPV-positive cervical cancer cells, highlighting that inhibition of TMEM45A may be a therapeutic strategy for HPV-positive cervical cancer.

Identification of a Resistance Mechanism to IGF-IR Targeting in Human Triple Negative MDA-MB-231 Breast Cancer Cells

Triple negative breast cancer (TNBC) is associated with unfavorable prognosis and high relapse rates following chemotherapy. There is an urgent need to develop effective targeted therapy for this BC subtype. The type I insulin-like growth factor receptor (IGF-IR) was identified as a potential target for BC management. We previously reported on the production of the IGF-Trap, a soluble IGF-1R fusion protein that reduces the bioavailability of circulating IGF-1 and IGF-2 to the cognate receptor, impeding signaling. In nude mice xenotransplanted with the human TNBC MDA-MB-231 cells, we found variable responses to this inhibitor. We used this model to investigate potential resistance mechanisms to IGF-targeted therapy. We show here that prolonged exposure of MDA-MB-231 cells to the IGF-Trap in vitro selected a resistant subpopulation that proliferated unhindered in the presence of the IGF-Trap. We identified in these cells increased fibroblast growth factor receptor 1 (FGFR1) activation levels that sensitized them to the FGFR1-specific tyrosine kinase inhibitor PD166866. Treatment with this inhibitor caused cell cycle arrest in both the parental and resistant cells, markedly increasing cell death in the latter. When combined with the IGF-Trap, an increase in cell cycle arrest was observed in the resistant cells. Moreover, FGFR1 silencing increased the sensitivity of these cells to IGF-Trap treatment in vivo. Our data identify increased FGFR1 signaling as a resistance mechanism to targeted inhibition of the IGF-IR and suggest that dual IGF-1R/FGFR1 blockade may be required to overcome TNBC cell resistance to IGF-axis inhibitors.

Niche Modulation of IGF-1R Signaling: Its Role in Stem Cell Pluripotency, Cancer Reprogramming, and Therapeutic Applications

Stem cells work with their niches harmoniously during development. This concept has been extended to cancer pathology for cancer stem cells (CSCs) or cancer reprogramming. IGF-1R, a classical survival signaling, has been shown to regulate stem cell pluripotency, CSCs, or cancer reprogramming. The mechanism underlying such cell fate determination is unclear. We propose the determination is due to different niches in embryo development and tumor malignancy which modulate the consequences of IGF-1R signaling. Here we highlight the modulations of these niche parameters (hypoxia, inflammation, extracellular matrix), and the targeted stem cells (embryonic stem cells, germline stem cells, and mesenchymal stem cells) and CSCs, with relevance to cancer reprogramming. We organize known interaction between IGF-1R signaling and distinct niches in the double-sided cell fate with emerging trends highlighted. Based on these new insights, we propose that, through targeting IGF-1R signaling modulation, stem cell therapy and cancer stemness treatment can be further explored.

Stem cell-secreted 14,15- epoxyeicosatrienoic acid rescues cholesterol homeostasis and autophagic flux in Niemann-Pick-type C disease

We previously demonstrated that the direct transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) into the dentate gyrus ameliorated the neurological symptoms of Niemann–Pick type C1 (NPC1)-mutant mice. However, the clinical presentation of NPC1-mutant mice was not fully understood with a molecular mechanism. Here, we found 14,15-epoxyeicosatrienoic acid (14,15-EET), a cytochrome P450 (CYP) metabolite, from hUCB-MSCs and the cerebella of NPC1-mutant mice and investigated the functional consequence of this metabolite. Our screening of the CYP2J family indicated a dysregulation in the CYP system in a cerebellar-specific manner. Moreover, in Purkinje cells, CYP2J6 showed an elevated expression level compared to that of astrocytes, granule cells, and microglia. In this regard, we found that one CYP metabolite, 14,15-EET, acts as a key mediator in ameliorating cholesterol accumulation. In confirming this hypothesis, 14,15-EET treatment reduced the accumulation of cholesterol in human NPC1 patient-derived fibroblasts in vitro by suppressing cholesterol synthesis and ameliorating the impaired autophagic flux. We show that the reduced activity within the CYP system in the cerebellum could cause the neurological symptoms of NPC1 patients, as 14,15-EET treatment significantly rescued cholesterol accumulation and impaired autophagy. We also provide evidence that the intranasal administration of hUCB-MSCs is a highly promising alternative to traumatic surgical transplantation for NPC1 patients.

An acid secreted by stem cells can reduce the excess cholesterol caused by a genetic metabolic disorder. Niemann–Pick type C disease is a rare, inherited condition that causes defective muscular development and progressive neurological degeneration. A key disease mechanism is the excessive accumulation of cholesterol within cells. Kyung-Sun Kang at Seoul National University, South Korea, and co-workers have demonstrated that a metabolite molecule called 14,15-epoxyeicosatrienoic acid (14,15-EET) derived from stem cells from human umbilical cord blood significantly reduced cholesterol in Neimann-Pick Type C mouse models and human cell samples. The team administered the stem cell therapy non-invasively via the nose, and observed significant improvements in motor function in the mice. Experiments in both animals and cells showed that the treatment resulted in reduced cholesterol levels and the correction of defective signalling within cells.

Inhibition by miR-410 facilitates direct retinal pigment epithelium differentiation of umbilical cord blood-derived mesenchymal stem cells

Retinal pigment epithelium (RPE) is a major component of the eye. This highly specialized cell type facilitates maintenance of the visual system. Because RPE loss induces an irreversible visual impairment, RPE generation techniques have recently been investigated as a potential therapeutic approach to RPE degeneration. A microRNA-based technique is a new strategy for producing RPE cells from adult stem cell sources. Previously, we identified that antisense microRNA-410 (anti-miR-410) induces RPE differentiation from amniotic epithelial stem cells. In this study, we investigated RPE differentiation from umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) via anti-miR-410 treatment. We identified miR-410 as a RPE-relevant microRNA in UCB-MSCs from among 21 putative human RPE-depleted microRNAs. Inhibition of miR-410 induces overexpression of immature and mature RPE-specific factors, including MITF, LRAT, RPE65, Bestrophin, and EMMPRIN. The RPE-induced cells were able to phagocytize microbeads. Results of our microRNA-based strategy demonstrated proof-of-principle for RPE differentiation in UCB-MSCs by using anti-miR-410 treatment without the use of additional factors or exogenous transduction.

The Roles of Insulin-Like Growth Factors in Mesenchymal Stem Cell Niche

Many tissues contain adult mesenchymal stem cells (MSCs), which may be used in tissue regeneration therapies. However, the MSC availability in most tissues is limited which demands expansion in vitro following isolation. Like many developing cells, the state of MSCs is affected by the surrounding microenvironment, and mimicking this natural microenvironment that supports multipotent or differentiated state in vivo is essential to understand for the successful use of MSC in regenerative therapies. Many researchers are, therefore, optimizing cell culture conditions in vitro by altering growth factors, extracellular matrices, chemicals, oxygen tension, and surrounding pH to enhance stem cells self-renewal or differentiation. Insulin-like growth factors (IGFs) system has been demonstrated to play an important role in stem cell biology to either promote proliferation and self-renewal or enhance differentiation onset and outcome, depending on the cell culture conditions. In this review, we will describe the importance of IGFs, IGF-1 and IGF-2, in development and in the MSC niche and how they affect the pluripotency or differentiation towards multiple lineages of the three germ layers.

The effect of fibroblast growth factor on distinct differentiation potential of cord blood-derived unrestricted somatic stem cells and Wharton's jelly-derived mesenchymal stem/stromal cells

BACKGROUND AIMS

Perinatal tissues are considered an attractive source of mesenchymal stem/stromal cells (MSCs) and have unique characteristics depending on their origin. In this study, we compared the basic characteristics of unrestricted somatic stem cells isolated from cord blood (CB-USSCs) and MSCs isolated from Wharton's jelly of umbilical cords (WJ-MSCs). We also evaluated the effect of basic fibroblast growth factor (bFGF) supplementation on the growth and differentiation of these cells.

METHODS

CB-USSCs and WJ-MSCs were isolated from the same individual (n = 6), and their morphology, cell surface antigens, proliferation, expression of stemness markers and adipogenic, osteogenic and chondrogenic differentiation potentials were evaluated. Their morphology, proliferation and differentiation potentials were then also compared in the presence of bFGF supplementation (10 ng/mL).

RESULTS

Overall, CB-USSCs expressed DLK-1 and negative for all the HOX gene markers. The expression of cell surface antigen CD90, growth capacity and adipogenic differential potential of CB-USSCs were lower than those of WJ-MSCs. WJ-MSCs showed higher growth capacity, but the expression of CD73 and CD105 and their osteogenic differentiation potential were lower than those of CB-USSCs. The spindle morphology of both CB-USSCs and WJ-MSCs and the growth and adipogenic differentiation of CB-USSCs were improved by bFGF supplementation. However, the bFGF supplement did not have any positive effect on the tri-lineage differentiation potentials of WJ-MSCs.

CONCLUSIONS

CB-USSCs and WJ-MSCs each had distinct characteristics including different growth capacity, distinguishable cell surface markers and distinct adipogenic and osteogenic potentials. bFGF supplementation improved the growth capacity and adipogenic differentiation of CB-USSCs.

Umbilical-cord-blood-derived mesenchymal stem cells seeded onto fibronectin-immobilized polycaprolactone nanofiber improve cardiac function

Stem cells seeded onto biofunctional materials have greater potency for therapeutic applications. We investigated whether umbilical-cord-blood-derived mesenchymal stem cell (UCB-MSC)-seeded fibronectin (FN)-immobilized polycaprolactone (PCL) nanofibers could improve cardiac function and inhibit left ventricle (LV) remodeling in a rat model of myocardial infarction (MI). Aligned nanofibers were uniformly coated with poly(glycidyl methacrylate) by initiated chemical vapor deposition followed by covalent immobilization of FN proteins. The degree of cell elongation and adhesion efficacy were improved by FN immobilization. Furthermore, genes related to angiogenesis and mesenchymal differentiations were up-regulated in the FN-immobilized PCL nanofibers in comparison to control PCL nanofibers in vitro. 4 weeks after the transplantation in the rat MI model, the echocardiogram showed that the UCB-MSC-seeded FN-immobilized PCL nanofiber group increased LV ejection fraction and fraction shortening as compared to the non-treated control and acellular FN-immobilized PCL nanofiber groups. Histological analysis indicated that the implantation of UCB-MSCs with FN-immobilized PCL nanofibers induced a decrease in MI size and fibrosis, and an increase in scar thickness. This study indicates that FN-immobilized biofunctional PCL nanofibers could be an effective carrier for UCB-MSC transplantation for the treatment of MI.

Isolation and characterization of canine Wharton's jelly-derived mesenchymal stem cells

Wharton's jelly is a known stem cell source in humans. Because stem cells might provide a potential therapeutic role in canines, many stem cell sources are studied for isolation and characterization in the canine system. So far, there have been no reports identifying canine Wharton's jelly stem cells. In this study, we successfully isolated and characterized mesenchymal stem cells (MSCs) from canine Wharton's jelly. Canine Wharton's jelly-derived mesenchymal stem cells (cWJ-MSCs) that were grown in low-glucose DMEM medium have spindle-like shapes similar to human Wharton's jelly stem cells. We characterized the immunophenotypes of canine Wharton's jelly stem cells by FACS analysis and measured the cumulative population doubling level (CPDL). We investigated the differentiation of cWJ-MSCs with a trilineage differentiation assay to determine whether they were mesenchymal. Under various differentiation conditions, cWJ-MSCs presented chondrogenic, osteogenic, adipogenic, and neurogenic differentiation abilities in vitro. In conclusion, our results show that cWJ-MSCs might be a good source for stem cells. Furthermore, cWJ-MSCs might be useful as a cell therapy application for veterinary medicine.

Transplantation of human umbilical cord blood or amniotic epithelial stem cells alleviates mechanical allodynia after spinal cord injury in rats

Stem cell therapy is a potential treatment for spinal cord injury (SCI), and a variety of different stem cell types have been grafted into humans suffering from spinal cord trauma or into animal models of spinal injury. Although several studies have reported functional motor improvement after transplantation of stem cells into injured spinal cord, the benefit of these cells for treating SCI-induced neuropathic pain is not clear. In this study, we investigated the therapeutic effect of transplanting human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) or amniotic epithelial stem cells (hAESCs) on SCI-induced mechanical allodynia (MA) and thermal hyperalgesia (TH) in T13 spinal cord hemisected rats. Two weeks after SCI, hUCB-MSCs or hAESCs were transplanted around the spinal cord lesion site, and behavioral tests were performed to evaluate changes in SCI-induced MA and TH. Immunohistochemical and Western blot analyses were also performed to evaluate possible therapeutic effects on SCI-induced inflammation and the nociceptive-related phosphorylation of the NMDA NR1 receptor subunit. While transplantation of hUCB-MSCs showed a tendency to reduce MA, transplantation of hAESCs significantly reduced MA. Neither hUCB-MSC nor hAESC transplantation had any effect on SCI-induced TH. Transplantation of hAESCs also significantly reduced the SCI-induced increase in NMDA receptor NR1 subunit phosphorylation (pNR1) expression in the spinal cord. Both hUCB-MSCs and hAESCs reduced the SCI-induced increase in spinal cord expression of the microglial marker, F4/80, but not the increased expression of GFAP or iNOS. Taken together, these findings demonstrate that the transplantation of hAESCs into the injured spinal cord can suppress mechanical allodynia, and this effect seems to be closely associated with the modulation of spinal cord microglia activity and NR1 phosphorylation.

Isolation and characterization of antler-derived multipotent stem cells

Recent studies have reported that stem cells can be isolated from various tissues such as bone marrow, fatty tissue, umbilical cord blood, Wharton's jelly, and placenta. These types of stem cell studies have also arisen in veterinary medicine. Deer antlers show a seasonal regrowth of tissue, an unusual feature in mammals. Antler tissue therefore might offer a source of stem cells. To explore the possibility of stem cell populations within deer antlers, we isolated and successfully cultured antler-derived multipotent stem cells (MSCs). Antler MSCs were maintained in a growth medium, and the proliferation potential was measured via an assay called the cumulative population doubling level. Immunophenotyping and immunostaining revealed the intrinsic characteristic stem cell markers of antler MSCs. To confirm the ability to differentiate, we conducted osteogenic, adipogenic, and chondrogenic induction under the respective differentiation conditions. We discovered that antler MSCs have the ability to differentiate into multiple lineages. In conclusion, our results show that deer antler tissue may contain MSCs and therefore may be a potential source for veterinary regenerative therapeutics.

Transcriptional differences between rhesus embryonic stem cells generated from in vitro and in vivo derived embryos

Numerous studies have focused on the transcriptional signatures that underlie the maintenance of embryonic stem cell (ESC) pluripotency. However, it remains unclear whether ESC retain transcriptional aberrations seen in in vitro cultured embryos. Here we report the first global transcriptional profile comparison between ESC generated from either in vitro cultured or in vivo derived primate embryos by microarray analysis. Genes involved in pluripotency, oxygen regulation and the cell cycle were downregulated in rhesus ESC generated from in vitro cultured embryos (in vitro ESC). Significantly, several gene differences are similarly downregulated in preimplantation embryos cultured in vitro, which have been associated with long term developmental consequences and disease predisposition. This data indicates that prior to derivation, embryo quality may influence the molecular signature of ESC lines, and may differentially impact the physiology of cells prior to or following differentiation.

Isolation and characterization of canine amniotic membrane-derived multipotent stem cells

Recent studies have shown that amniotic membrane tissue is a rich source of stem cells in humans. In clinical applications, the amniotic membrane tissue had therapeutic effects on wound healing and corneal surface reconstruction. Here, we successfully isolated and identified multipotent stem cells (MSCs) from canine amniotic membrane tissue. We cultured the canine amniotic membrane-derived multipotent stem cells (cAM-MSCs) in low glucose DMEM medium. cAM-MSCs have a fibroblast-like shape and adhere to tissue culture plastic. We characterized the immunophenotype of cAM-MSCs by flow cytometry and measured cell proliferation by the cumulative population doubling level (CPDL). We performed differentiation studies for the detection of trilineage multipotent ability, under the appropriate culture conditions. Taken together, our results show that cAM-MSCs could be a rich source of stem cells in dogs. Furthermore, cAM-MSCs may be useful as a cell therapy application for veterinary regenerative medicine.

SOX2 has a crucial role in the lineage determination and proliferation of mesenchymal stem cells through Dickkopf-1 and c-MYC

SOX2 is a well-known core transcription factor in embryonic stem cells (ESCs) and has an important role in the maintenance of pluripotency. Recently, SOX2 expression has also been reported in adult stem cells (ASCs), but the role of SOX2 in ASCs remains unknown. In this study, we examined the molecular mechanisms of SOX2 in human mesenchymal stem cells (hMSCs), a type of ASCs, by performing inhibition studies. SOX2 inhibition resulted in altered cell growth and differentiation capabilities. These changes coincided with a decrease in Dickkopf-1 (DKK1), a soluble inhibitor of WNT signaling. Chromatin immunoprecipitation and luciferase assays showed that SOX2 binds to DKK1 and has a positive regulatory role in transcription. The enforced expression of DKK1 in SOX2-inhibited hMSCs reversed the differentiation deformities, but could not abrogate the cell proliferation defect. Proliferation was regulated by c-MYC, whose expression can also be controlled by SOX2. Our study shows that SOX2 directly regulates DKK1 expression and, as a consequence, determines the differentiation lineage of hMSCs. Moreover, SOX2 also regulates proliferation by affecting c-MYC. Therefore, these results suggest that SOX2 might have a specific function by regulating DKK1 and c-MYC in the differentiation and growth of ASCs, which is separate from its roles in ESCs.

Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Protect against Neuronal Cell Death and Ameliorate Motor Deficits in Niemann Pick Type C1 Mice

Niemann Pick disease type C1 (NPC) is an autosomal recessive disease characterized by progressive neurological deterioration leading to premature death. In this study, we hypothesized that human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) have the multifunctional abilities to ameliorate NPC symptoms in the brain. To test this hypothesis, hUCB-MSCs were transplanted into the hippocampus of NPC mice in the early asymptomatic stage. This transplantation resulted in the recovery of motor function in the Rota Rod test and impaired cholesterol homeostasis leading to increased levels of cholesterol efflux-related genes such as LXRα, ABCA1, and ABCG5 while decreased levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase were observed in NPC mice. In the cerebrum, hUCB-MSCs enhanced neuronal cell survival and proliferation, where they directly differentiated into electrically active MAP2-positive neurons as demonstrated by whole-cell patch clamping. In addition, we observed that hUCB-MSCs reduced Purkinje neuronal loss by suppression of inflammatory and apoptotic signaling in the cerebellum as shown by immunohistochemistry. We further investigated how hUCB-MSCs enhance cellular survival and inhibit apoptosis in NPC mice. Neuronal cell survival was associated with increased PI3K/AKT and JAK2/STAT3 signaling; moreover, hUCB-MSCs modulated the levels of GABA/glutamate transporters such as GAT1, EAAT2, EAAT3, and GAD6 in NPC mice as assessed by Western blot analysis. Taken together, our findings suggest that hUCB-MSCs might play multifunctional roles in neuronal cell survival and ameliorating motor deficits of NPC mice.

Isolation and characterization of equine amniotic fluid-derived multipotent stem cells

BACKGROUND AIMS

Amniotic fluid (AF) is a well-known source of stem cells. However, there have been no reports regarding equine AF stem cells. We have isolated equine AF-derived multipotent stem cells (MSC) (eAF-MSC) and show that these cells exhibit self-renewal ability and multilineage differentiation.

METHODS

AF was obtained from thoroughbred mares and mononuclear cells (MNC) were isolated by Ficoll-Paque density gradient. We measured the cumulative population doubling level (CPDL) and characterized the immunophenotype by flow cytometry. To investigate differentiation ability, a trilineage differentiation assay was conducted.

RESULTS

eAF-MSC could be isolated and the proliferation level was high. eAF-MSC presented typical MSC phenotypic markers, as determined by flow cytometry. Moreover, eAF-MSC showed a trilineage differentiation capability.

CONCLUSIONS

Equine AF is a good source of MSC. Furthermore, eAF-MSC may be useful as a cell therapy application for horses.