Lingling Hou

Inhibitory effect and mechanism of mesenchymal stem cells on liver cancer cells

Mesenchymal stem cells (MSCs), with their capacity for self-renewal and differentiation into various cell types, are important seed cells for stem cell therapy. MSCs exhibit potent pathotropic migratory properties that make them attractive for use in tumor prevention and therapy. However, little is known about the underlying molecular mechanisms that link MSCs to the targeted tumor cells. This study investigated the inhibitory effect and mechanism of MSCs on human hepatoma HepG2 cells using co-culture and conditioned medium system and animal transplantation model. The HepG2 cells were co-cultured with MSCs or treated with conditional media derived from MSCs cultures in vitro. Results of methylthiazolyldiphenyl tetrazolium assay and flow cytometric assay showed that the proliferation and apoptosis of HepG2 cells decreased and increased, respectively. Reverse transcription polymerase chain reaction analysis showed that the expression levels of bcl-2, c-Myc, β-catenin, and survivin were downregulated. The results of enzyme-linked immunosorbent assay and Western blot proved that MSCs secreted Dkk-1 to inhibit the expression of Wnt signaling pathway-related factors (bcl-2, c-Myc, β-catenin, and survivin) in tumor cells, consequently inhibiting the proliferation and promoting the apoptosis of HepG2 cells. Animal transplantation experiment showed that tumor growth was significantly inhibited when HepG2 cells were co-injected with MSCs into nude mice. These results suggested that MSCs inhibited the growth and promoted the apoptosis of HepG2 cells in a dose-dependent manner. This study provided a new approach and experimental basis for cancer therapy. This study also proved that the Wnt signaling pathway may have a function in MSC-mediated tumor cell inhibition.

Administration of amyloid-β42 oligomer-specific monoclonal antibody improved memory performance in SAMP8 mice.

Amyloid-β peptide (Aβ) is recognized by many as the leading cause of Alzheimers disease (AD), and Aβ oligomers play a major role in the early-onset form of AD. Recently, the application of passive immunization targeting Aβ has been investigated as a potential method of AD immunotherapy. We used a strain of monoclonal antibody against Aβ42 oligomers, designated A8, as an Aβ inhibitor to suppress Aβ aggregation and Aβ-derived cell toxicity in vitro, and as a passive immunotherapy approach to treat SAMP8 (senescence accelerated mouse sub-line P8) mice, an animal model of AD, in vivo. First, our results showed that pre-incubation of A8 with Aβ oligomers inhibited both the maturation of Aβ fiber and Aβ oligomer toxicity on SH-SY5Y cells. Second, learning and memory was improved through intraperitoneal administration of A8 in SAMP8 mice. Third, Aβ pathology was ameliorated with decreased Aβ oligomers and phospho-tau levels in SAMP8 mice. Our data suggest that our monoclonal antibody A8 may be a candidate as a potential immunotherapeutic agent in AD.

The effects of amyloid-β42 oligomer on the proliferation and activation of astrocytes in vitro

Previous studies reported that astrocyte response to amyloid-β (Aβ) before obvious neuronal damage could be detected in Alzheimer’s disease (AD). It is suggested that astrocytes play a key role in AD pathologies. In this study, we investigated the effects of Aβ42 oligomer on the proliferation and activation of astrocytes by in vitro experiments. The results showed that Aβ42 oligomers could convert astrocytes to responsive astrocytes. It was revealed by MTT and ELISA assays that the viability of astrocytes gradually decreased, and the release of brain-derived neurotrophic factor increased with elevated Aβ42 concentration and prolonged duration. Reverse-transcription polymerase chain reaction (RT-PCR) assay indicated that Aβ42 oligomers increased the expression of glial fibers acid protein and interleukin-1β in a dose-dependent but not time-dependent manner. It was showed that A8, a mouse monoclonal antibody, was able to protect the cultured astrocytes against the toxicity of Aβ42 oligomers. The result demonstrated that A8 could inhibit Aβ42 oligomers toxic effects on astrocytes and that, alone, A8 could promote the proliferation of astrocytes in certain time. The present study laid a theoretical foundation for further understanding the effects of Aβ42 on astrocytes and, hence, is conducive to the theoretical understanding and clinical therapies of AD progression.

Isolation and biological characterization of chicken amnion epithelial cells

Amniotic epithelial cells (AECs) express Oct4, Nanog and Sox-2, which are necessary for maintaining the undifferentiated state of pluripotent stem cells. AECs additionally express CK19, which is a specific marker of epithelial cells, both in vivo and in vitro. In this research, we investigated the biological characteristics and potential for cell therapy of AECs from 6-day-old chicken embryos. We induced the AECs to differentiate into pancreatic islet-like cells (endoderm), adipocytes and osteoblasts (mesoderm) and neural-like cells (ectoderm), and used immunofluorescence and RT-PCR to detect the expression of AECs specific markers. To assess the differentiation capacity of AECs, passage 3 cells were induced to differentiate into adipocytes, osteoblasts, pancreatic islet-like cells and neural-like cells. The AEC markers, Oct-4, Nanog, Sox-2 and CK19, were all positively expressed. Cloning efficiency decreased with increasing passage number. Passage 3 AECs were successfully induced to differentiate into pancreatic islet-like cells, osteoblasts, adipocytes, and neural-like cells. These results suggested that AECs isolated from chicken embryos exhibited the characteristics of the multipotent stem cells. AECs may therefore be ideal candidates for cellular transplantation therapy and tissue engineering.

Isolation and characterization of mesenchymal stem cells from chicken bone marrow.

The bone marrow mesenchymal stem cells (BMSCs) are multipotent stem cells, which can differentiate in vitro into many cell types. However, the vast majority of experimental materials were obtained from human, mouse, rabbit and other mammals, but rarely in poultry. So, in this study, Thirty- to sixty-day old chicken was chosen as experimental animal, to isolate and characterize BMSCs from them. To investigate the biological characteristics of chicken BMSCs, immunofluorescence and RT-PCR were used to detect the characteristic surface markers of BMSCs. Growth curves were drawn in accordance with cell numbers. To assess the differentiation capacity of the BMSCs, cells were induced to differentiate into osteoblasts, adipocytes, and endothelial cells. The surface markers of BMSCs, CD29, CD44, CD31, CD34, CD71 and CD73, were detected by immunofluorescence and RT-PCR assays. The growth curves of different passages were all typically sigmoidal. Karyotype analysis showed that these in vitro cultured cells were genetically stable. In addition, BMSCs were successfully induced to differentiate into osteoblasts, adipocytes, and endothelial cells. The results suggest that the BMSCs isolated from chicken possess similar biological characteristics with those separated from other species, and their multi-lineage differentiation potentiality herald a probable application for cellular transplant therapy in tissue engineering.

Biological characterization of chicken mesenchymal stem/progenitor cells from umbilical cord Wharton’s Jelly

Mesenchymal stem/progenitor cells derived from Wharton’s jelly of the umbilical cord (UCMSCs/UCMPCs) are multipotent, and can be differentiated in vitro into many cell types. Much work has been done on UCMSCs/UCMPCs from humans, mice, rabbits, and other mammals, but the relatively little literature has been published about these cells in chickens. In our work, we isolated USMSCs/USMPCs from chicken embryos. We characterized the isolated cells using immunofluorescence and reverse transcription polymerase chain reaction techniques. Primary UCMSCs/UCMPCs were subcultured to passage 30 and growth curves for each passage determined. The growth curves at different passages were all typically sigmoidal. Isolated UCMSCs/UCMPCs were induced to differentiate into adipocytes, osteoblasts, myocardial cells, and neural cells, and we were able to detect characteristic CD44, CD29, CD73, and CD71 cell surface markers. Our results suggest that UCMSCs/UCMPCs isolated from chickens possess similar biological characteristics to those from other species. Their multi-lineage differentiation capabilities herald a probable application for cellular transplant therapy in tissue engineering.Mesenchymal stem/progenitor cells derived from Wharton’s jelly of the umbilical cord (UCMSCs/UCMPCs) are multipotent, and can be differentiated in vitro into many cell types. Much work has been done on UCMSCs/UCMPCs from humans, mice, rabbits, and other mammals, but the relatively little literature has been published about these cells in chickens. In our work, we isolated USMSCs/USMPCs from chicken embryos. We characterized the isolated cells using immunofluorescence and reverse transcription polymerase chain reaction techniques. Primary UCMSCs/UCMPCs were subcultured to passage 30 and growth curves for each passage determined. The growth curves at different passages were all typically sigmoidal. Isolated UCMSCs/UCMPCs were induced to differentiate into adipocytes, osteoblasts, myocardial cells, and neural cells, and we were able to detect characteristic CD44, CD29, CD73, and CD71 cell surface markers. Our results suggest that UCMSCs/UCMPCs isolated from chickens possess similar biological characteristics to those from other species. Their multi-lineage differentiation capabilities herald a probable application for cellular transplant therapy in tissue engineering.

Characterization of vascular endothelial progenitor cells from chicken bone marrow

BackgroundEndothelial progenitor cells (EPC) are a type of stem cell used in the treatment of atherosclerosis, vascular injury and regeneration. At present, most of the EPCs studied are from human and mouse, whereas the study of poultry-derived EPCs has rarely been reported. In the present study, chicken bone marrow-derived EPCs were isolated and studied at the cellular level using immunofluorescence and RT-PCR.ResultsWe found that the majority of chicken EPCs were spindle shaped. The growth-curves of chicken EPCs at passages (P) 1, -5 and -9 were typically “S”-shaped. The viability of chicken EPCs, before and after cryopreservation was 92.2% and 81.1%, respectively. Thus, cryopreservation had no obvious effects on the viability of chicken EPCs. Dil-ac-LDL and FITC-UAE-1 uptake assays and immunofluorescent detection of the cell surface markers CD34, CD133, VEGFR-2 confirmed that the cells obtained in vitro were EPCs. Observation of endothelial-specific Weibel-Palade bodies using transmission electron microscopy further confirmed that the cells were of endothelial lineage. In addition, chicken EPCs differentiated into endothelial cells and smooth muscle cells upon induction with VEGF and PDGF-BB, respectively, suggesting that the chicken EPCs retained multipotency in vitro.ConclusionsThese results suggest that chicken EPCs not only have strong self-renewal capacity, but also the potential to differentiate into endothelial and smooth muscle cells. This research provides theoretical basis and experimental evidence for potential therapeutic application of endothelial progenitor cells in the treatment of atherosclerosis, vascular injury and diabetic complications.

Derivation and characteristics of pluripotent embryonic germ cells in duck

Embryonic germ (EG) cells derived from primordial germ cells are undifferentiated and pluripotent stem cells. In our study, primordial germ cells isolated from the genital ridges of Beijing duck (Anas domestica) embryo at stage 28 were co-cultured with mice embryonic fibroblasts. Duck EG cells grew with a high nuclear:cytoplasm ratio and were positive for periodic acid-Schiff and alkaline phosphatase staining. The duck EG cells could proliferate for more than a month in repeated subculture and maintain a diploid karyotype. They expressed the pluripotent markers such as stage-specific embryonic antigen-1, stage-specific embryonic antigen-4, tumor rejection antigen-1-60, and tumor rejection antigen-1-81. Furthermore, the EG cells could form embryoid bodies and differentiate to osteoblast in vitro. This study explored the isolation and culture process of duck EG cells using the culture methods of chicken EG cells and investigated biological characteristics of Beijing duck EG cells. Our results showed that methods published for the culture of chicken EG cells could be applied to the culture of duck EG cells. Duck EG cells will be useful for the differentiation of EG cells in avian species.

On-column refolding purification of DT389-hIL13 recombinant protein expressed in Escherichia coli.

Protein refolding is a bottleneck in the production of therapeutic proteins from inclusion bodies. In recent years, several studies have described on-column refolding of recombinant proteins. DT389-hIL13 is a recombinant protein that targets the glioma. In our study, the recombinant protein DT389-hIL13 was expressed in Escherichia coli (E. coli). The isolated inclusion bodies were refolded using size exclusion chromatography (SEC) and further purified using anion exchange chromatography. Three different methods of SEC on-column refolding were studied. In vitro tests on U251 cells showed that the recombinant protein could effectively inhibit the proliferation of U251 cells, especially the protein refolded by urea and pH gradient method. The half-maximal inhibitory concentration (IC50) of 0.887 nM was achieved with this new method, unlike an IC50 of 11.4 nM achieved in the non-gradient method.

The Inhibitory Effect of Mesenchymal Stem Cells with rAd-NK4 on Liver Cancer

Mesenchymal stem cells (MSCs) can migrate to the tumor site and integrate into the tumor tissue. As a delivery vehicle of antitumor factors, MSCs have been tried in various tumor therapies. NK4 can both inhibit the growth, metastasis, and invasion of tumor cells induced by hepatocyte growth factor (HGF) and suppress tumor angiogenesis that is independent on HGF/cellular-mesenchymal-to-transition factor pathway. Adenovirus can directly deliver NK4 for tumor treatment but may induce immunological rejection. We combined MSCs with an adenovirus vector to deliver NK4 for liver tumor treatment. This study detected the migration of MSCs to high metastasis liver carcinoma cells MHCC-97H in vitro, investigated the inhibitory effect of rAd-NK4-MSCs on the growth and metastasis of MHCC-97H cells, further explored the inhibitory mechanism of rAd-NK4-MSCs to MHCC-97H cell metastasis, and examined the inhibitory effect of rAd-NK4-MSCs on the migration of human umbilical vein endothelial cells (HUVECs) in vitro. In this study, migration experiment was used for the potential capacity of MSCs and inhibition on migration of rAd-NK4-MSCs. Western blot was used for detecting the inhibition mechanism of rAd-NK4-MSCs to MHCC-97H cells. And, animal transplantation experiment was used for the inhibition of rAd-NK4-MSCs in vivo. MSC migration assay showed MSCs can significantly migrate to MHCC-97H cells. Co-culture results indicated that rAd-NK4-MSCs significantly inhibited the proliferation and migration of MHCC-97H cells in vitro. Western blot results proved that rAd-NK4-MSCs inhibited MHCC-97H cell migration correlating with suppressing Erk1/2 phosphorylation. HUVEC migration experiment suggested that rAd-NK4-MSCs had a potential of inhibiting tumor angiogenesis. Animal transplantation experiment showed that the tumor growth was significantly inhibited in the rAd-NK4-MSC group. Taken together, this study proved that NK4-modified MSCs had an inhibitory effect on the growth and migration of MHCC-97H cells and tumor angiogenesis, which provided a new strategy for liver tumor target therapy.