Influence of serum from liver-damaged rats on differentiation tendency of bone marrow-derived stem cells

Serum from CCl4-induced acute rat injury model induces differentiation of ADSCs towards hepatic cells and reduces liver fibrosis

Cellular therapies hold promise to alleviate liver diseases. This study explored the potential of allogenic serum isolated from rat with acute CCl₄ injury to differentiate adipose derived stem cells (ADSCs) towards hepatic lineage. Acute liver injury was induced by CCl₄ which caused significant increase in serum levels of VEGF, SDF1α and EGF. ADSCs were preconditioned with 3% serum isolated from normal and acute liver injury models. ADSCs showed enhanced expression of hepatic markers (AFP, albumin, CK8 and CK19). These differentiated ADSCs were transplanted intra-hepatically in CCl₄-induced liver fibrosis model. After one month of transplantation, fibrosis and liver functions (alkaline phosphatase, ALAT and bilirubin) showed marked improvement in acute injury group. Elevated expression of hepatic (AFP, albumin, CK 18 and HNF4a) and pro survival markers (PCNA and VEGF) and improvement in liver architecture as deduced from results of alpha smooth muscle actin, Sirius red and Masson's trichome staining was observed.

Yi Guan Jian decoction may enhance hepatic differentiation of bone marrow‑derived mesenchymal stem cells via SDF‑1 in vitro

A previous study reported that Yi Guan Jian (YGJ) may increase the proliferation and differentiation of hepatic oval cells in a rat liver cirrhosis model. The aim of the present study was to investigate the effect and mechanism of action of YGJ on inducing hepatic differentiation in bone marrow-derived mesenchymal stem cells (BM-MSCs) via stromal-cell derived factor-1 (SDF-1). Murine BM-MSCs were isolated with whole bone marrow adherence, then identified by immunocytochemical staining and flow cytometry. Passage 2 cells were divided into 8 groups and their differentiation was induced by cell factors added to the medium, including hepatocyte growth factor (HGF), SDF-1 and YGJ. Each of the cell factors was used alone and any two or three of them were combined to establish different cell microenvironments in the different treatment groups. Albumin (ALB) was selected as a hepatocellular marker and cytokeratin-18 (CK-18) as a cholangiocellular marker. The protein and mRNA expression levels of ALB and CK-18 were used to determine the differentiation of BM-MSCs using immunocytochemical staining, western blotting and reverse transcription-quantitative polymerase chain reaction on days 7, 14, 21 and 28 during induction. The relative expression levels of ALB and CK-18 resulted in time-dependent increases in the groups supplemented only with HGF, SDF-1 or YGJ. Combination treatment of any two HGF, SDF-1 and YGJ led to a higher expression of ALB and CK-18 compared with only one cell factor treatment. Additionally, when all three were used in a combined treatment the expression levels of ALB and CK-18 occurred at an earlier time and was higher overall. Therefore, the present study suggested that YGJ had an effect on inducing hepatic differentiation in BM-MSCs via SDF-1 and may act in a synergistic manner with HGF and SDF-1.

Dynamic expression characteristics of Notch signal in bone marrow-derived mesenchymal stem cells during the process of differentiation into hepatocytes

Notch signaling is often involved in early development which helps to determine the differentiation state and fate of stem cells destined to form different tissues in the body. Its role in the differentiation of BM-MSCs (bone marrow-derived mesenchymal stem cells) is much less clear. As there is great interest in the potential of BM-MSCs as a source of cells for treating liver damage, it is important to understand if Notch signaling promotes or suppresses BM-MSCs differentiation into hepatocytes. In the present study, RT-PCR, Western blot results and morphologic changes demonstrated that BM-MSCs could successfully differentiate into hepatocytes in our special induction system including the tissue extract of damaged liver. On the 21st day when the differentiation direction was determined in BM-MSCs, the mRNA level of Jagged2, Delta1, Delta3, Notch1, Notch2, Notch3 and Presenilin1, was significantly lower than that on days 0, 7, and 11. In the further experiments, down-regulation of Notch signaling was shown to be critical for BM-MSCs to differentiate into hepatocytes, as increased Jagged1 resulted in up-regulated Notch activation leading to higher levels of expression of Hes1 and Hey1, which completely blocked Albumin expresion in BM-MSCs. These results in our study showed that Notch signaling in BM-MSCs was necessary to initiate differentiation into hepatocytes, but must be down-regulated for the differentiation to proceed continuously.

VEGF(165) expressing bone marrow mesenchymal stem cells differentiate into hepatocytes under HGF and EGF induction in vitro

A short half-life and low levels of growth factors in an injured microenvironment necessitates the sustainable delivery of growth factors and stem cells to augment the regeneration of injured tissues. Our aim was to investigate the ability of VEGF(165) expressing bone marrow mesenchymal stem cells (BMMSCs) to differentiate into hepatocytes when cultured with hepatocyte growth factor (HGF) and epidermal growth factor (EGF) in vitro. We isolated, cultured and identified rabbit BMMSCs, then electroporated the BMMSCs with VEGF(165)-pCMV6-AC-GFP plasmid. G418 was used to select transfected cells and the efficiency was up to 70%. The groups were then divided as follows: Group A was electroporated with pCMV6-AC-GFP plasmid + HGF + EGF and Group B was electroporated with VEGF(165)-pCMV6-AC-GFP plasmid +HGF + EGF. After 14 days, BMMSCs were induced into short spindle and polygonal cells. Alpha-fetoprotein (AFP) was positive and albumin (ALB) was negative in Group A, while both AFP and ALB were positive in group B on day 10. AFP and ALB in both groups were positive on day 20, but the quantity of AFP in group B decreased with prolonged time and was about 43.5% less than group A. The quantity of the ALB gene was increased with prolonged time in both groups. However, there was no significant difference between group A and B on day 10 and 20. Our results demonstrated that VEGF(165)-pCMV6-AC-GFP plasmid modified BMMSCs still had the ability to differentiate into hepatocytes. The VEGF(165) gene promoted BMMSCs to differentiate into hepatocyte-like cells under the induction of HGF and EGF, and reduced the differentiation time. These results have implications for cell therapies.

Proteome analysis of human Wharton's jelly cells during in vitro expansion

Background

The human umbilical cord contains mucoid connective tissue and fibroblast-like cells. These cells named Wharton's jelly cells, (WJCs) display properties similar to mesenchymal stem cells therefore representing a rich source of primitive cells to be potentially used in regenerative medicine.

Results

To better understand their self-renewal and potential in vitro expansion capacity, a reference 2D map was constructed as a proteomic data set. 158 unique proteins were identified. More than 30% of these proteins belong to cytoskeleton compartment. We also found that several proteins including Shootin1, Adenylate kinase 5 isoenzyme and Plasminogen activator-inhibitor 2 are no longer expressed after the 2^nd passage of in vitro replication. This indicates that the proliferative potency of these cells is reduced after the initial stage of in vitro growing. At the end of cellular culturing, new synthesized proteins, including, ERO1-like protein alpha, Aspartyl-tRNA synthetase and Prolyl-4-hydroxylase were identified. It is suggested that these new synthesized proteins are involved in the impairment of cellular surviving during replication and differentiation time.

Conclusions

Our work represents an essential step towards gaining knowledge of the molecular properties of WJCs so as to better understand their possible use in the field of cell therapy and regenerative medicine.

Granule formation in NGF-cultured mast cells is associated with expressions of pyruvate kinase type M2 and annexin I proteins

BACKGROUND

Nerve growth factor (NGF) is a potent mediator, which regulates characteristics of mast cells, but its biological function is not well characterized. This study aimed to screen proteins associated with the maturation of human mast cells-1 (HMC-1) or mouse bone marrow-derived mast cells (BMMCs) cultured with NGF, and to examine the functions of proteins involved.

METHODS

NGF (10 ng/ml) was added to cell culture medium every other day for 10 days for HMC-1 or twice a week for 5 weeks for BMMCs. Granule formation was determined by electron microscopy or May-Grunwald-Giemsa staining, TNF-alpha by ELISA, expressions of various proteins by two-dimensional gel electrophoresis (2-DE), siRNA transfection by Lipofectamine 2000, and the expressions of pyruvate kinase and annexin I by immunoblotting.

RESULTS

After NGF treatment, granule formation and total amounts of granular mediator, TNF-alpha increased in both mast cells. This TNF-alpha was released by calcium ionophore or by antigen/antibody reaction. Expressions of pyruvate kinase and annexin I obtained by 2-DE were confirmed by immunoblotting and siRNA-transfected HMC-1 cells. Expressions of proteins, granule formation and TNF-alpha content were blocked by both the TrkA inhibitor, K252a, and the ERK inhibitor, PD98059, but not by the PI3 kinase inhibitors, LY294002 and wortmannin.

CONCLUSION

These data suggest that pyruvate kinase and annexin I expressed by NGF contribute to granule formation containing TNF-alpha as well as other mediators in mast cells, which play a major role in allergic diseases via a TrkA/ERK pathway.

Down-regulation of Wnt signaling could promote bone marrow-derived mesenchymal stem cells to differentiate into hepatocytes

Bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated to be able to differentiate into hepatocytes, but the precise mechanisms controlling this process are unclear. Our aim is try to explore the role of Wnt signaling on the differentiation of BMSCs into hepatocytes. Our study demonstrated that BMSCs could successfully differentiate into hepatocytes under in vitro induction of the tissue extract of damaged liver. The mRNA level of Wnt-1, Wnt-5a, Frizzled1, DSH (disheveled), GSK-3beta (glycogen synthase kinase 3 beta) and beta-catenin on day 21 when the differentiation direction was determined, was lower than that on days 0, 7, and 11. Furthermore, blocking Wnt-1 signaling by treating BMSCs with Dkk1 could induce BMSCs to express albumin earlier and up-regulation of Wnt signaling by treating BMSCs with Wnt-1 could inhibit BMSCs to differentiate into hepatocytes. Above results indicated that inhibition on Wnt signaling can promote BMSCs to differentiate into hepatocytes.

Hepatic differentiation potential of commercially available human mesenchymal stem cells

The ready availability and low immunogenicity of commercially available mesenchymal stem cells (MSC) render them a potential cell source for the development of therapeutic products. With cell source a major bottleneck in hepatic tissue engineering, we investigated whether commercially available human MSC (hMSC) can transdifferentiate into the hepatic lineage. Based on previous studies that find rapid gain of hepatic genes in bone marrow-derived stem cells cocultured with liver tissue, we used a similar approach to drive hepatic differentiation by coculturing the hMSC with rat livers treated or untreated with gadolinium chloride (GdCl(3)). After a 24-hour coculture period with liver tissue injured by GdCl(3) in a Transwell configuration, approximately 34% of the cells differentiated into albumin-expressing cells. Cocultured cells were subsequently maintained with growth factors to complete the hepatic differentiation. Cocultured cells expressed more hepatic gene markers, and had higher metabolic functions and P450 activity than cells that were only differentiated with growth factors. In conclusion, commercially available hMSC do show hepatic differentiation potential, and a liver microenvironment in culture can provide potent cues to accelerate and deepen the differentiation. The ability to generate hepatocyte-like cells from a commercially available cell source would find interesting applications in liver tissue engineering.

Failure of hepatocyte marker-expressing hematopoietic progenitor cells to efficiently convert into hepatocytes in vitro

OBJECTIVE

Whether bone marrow (BM) hematopoietic stem/progenitor cells can directly differentiate into nonhematopoietic cells remains controversial. The aim of this study is to further investigate the potentiality of BM hematopoietic progenitor cells to convert into hepatocytes in vitro.

MATERIALS AND METHODS

Different subsets of BM cells from C57/BL6 mice were isolated using markers of hematopoietic stem cells by magnetic cell sorting and by flow cytometry. These cells were induced to transdifferentiate to hepatocytes in vitro in the presence of various cytokines or of hepatocytes (or tissue) from damaged liver, which have been reported to stimulate the conversion. Hepatic gene markers in freshly isolated or cultured BM cells were determined by reverse transcriptase polymerase chain reaction and immunofluorescence.

RESULTS

Freshly isolated hematopoietic progenitor cells (HPC) expressed a low level of messenger RNAs of hepatic cell-specific markers including albumin and alpha-fetoprotein (AFP), but did not significantly upregulate expression of these markers, even in the presence of cytokines or cocultured hepatocytes (or tissue). HPCs induced in vitro did not express the message of alpha-anti-trypsin-a mature hepatocyte marker. At protein level, the specific staining of AFP was not detected in the HPCs, either freshly isolated or in vitro induced. Albumin protein was detected in freshly isolated albumin mRNA-positive and -negative BM cell subpopulations. Albumin-stained BM cells disappeared after being induced for 5 days, but restained if mouse serum was supplemented in medium for a 24-hour extended culture, suggesting that albumin was absorbed by BM cells instead of de novo expression.

CONCLUSIONS

HPCs expressed mRNAs of hepatic cell markers, but could not efficiently convert into hepatocytes in vitro under our experimental conditions. Our observation raises a cautionary note in determining whether in vitro transdifferentiation of BM cells to hepatocytes can actually take place.

Stem cell proteomes: a profile of human mesenchymal stem cells derived from umbilical cord blood

Multipotent mesenchymal stem cells (MSCs) derived from human umbilical cord blood (UCB) represent promising candidates for the development of future strategies in cellular therapy. To create a comprehensive protein expression profile for UCB-MSCs, one UCB unit from a full-term delivery was isolated from the unborn placenta, transferred into culture, and their whole-cell protein fraction was subjected to two-dimensional electrophoresis (2-DE). Unambiguous protein identification was achieved with peptide mass fingerprinting matrix-assisted laser desorption/ionization - time of flight - mass spectrometry (MALDI-TOF-MS), peptide sequencing (MALDI LIFT-TOF/TOF MS), as well as gel-matching with previously identified databases. In overall five replicate 2-DE runs, a total of 2037 +/- 437 protein spots were detected of which 205 were identified representing 145 different proteins and 60 isoforms or post-translational modifications. The identified proteins could be grouped into several functional categories, such as metabolism, folding, cytoskeleton, transcription, signal transduction, protein degradation, detoxification, vesicle/protein transport, cell cycle regulation, apoptosis, and calcium homeostasis. The acquired proteome map of nondifferentiated UCB-MSCs is a useful inventory which facilitates the identification of the normal proteomic pattern as well as its changes due to activated or suppressed pathways of cytosolic signal transduction which occur during proliferation, differentiation, or other experimental conditions.