Human marrow-derived mesodermal progenitor cells generate insulin-secreting islet-like clusters in vivo

Enhanced differentiation of human amniotic fluid-derived stem cells into insulin-producing cells in vitro

AIMS/INTRODUCTION

To investigate the ability of human amniotic fluid stem cells (hAFSCs) to differentiate into insulin-producing cells.

MATERIALS AND METHODS

hAFSCs were induced to differentiate into pancreatic cells by a multistep protocol. The expressions of pancreas-related genes and proteins, including pancreatic and duodenal homeobox-1, insulin, and glucose transporter 2, were detected by polymerase chain reaction and immunofluorescence. Insulin secreted from differentiated cells was tested by enzyme-linked immunosorbent assay.

RESULTS

hAFSCs were successfully isolated from amniotic fluid that expressed the pluripotent markers of embryonic stem cells, such as Oct3/4, and mesenchymal stem cells, such as integrin β-1 and ecto-5'-nucleotidase. Here, we first obtained the hAFSCs that expressed pluripotent marker stage-specific embryonic antigen 1. Real-time polymerase chain reaction analysis showed that pancreatic and duodenal homeobox-1, paired box gene 4 and paired box gene 6 were expressed in the early phase of induction, and then stably expressed in the differentiated cells. The pancreas-related genes, such as insulin, glucokinase, glucose transporter 2 and Nkx6.1, were expressed in the differentiated cells. Immunofluorescence showed that these differentiated cells co-expressed insulin, C-peptide, and pancreatic and duodenal homeobox-1. Insulin was released in response to glucose stimulation in a manner similar to that of adult human islets.

CONCLUSIONS

The present study showed that hAFSCs, under selective culture conditions, could differentiate into islet-like insulin-producing cells, which might be used as a potential source for transplantation in patients with type 1 diabetes mellitus.

BDNF expression is up-regulated by progesterone in human umbilical cord mesenchymal stem cells

OBJECTIVE

To investigate whether promotion of neuronal differentiation of human umbilical cord mesenchymal stem cells (HUMSCs) by progesterone (PROG) involves changes in brain-derived neurotrophic factor (BDNF) levels.

METHODS

We used rat brain tissue extracts to mimic the brain microenvironment. Quantitative sandwich enzyme-linked immunosorbent assay was performed to measure levels of BDNF in cultured medium with or without PROG.

RESULTS

Progesterone increased levels of BDNF in HUMSCs.

CONCLUSION

Progesterone enhancement of brain-derived neurotrophic factor levels may be involved in PROG activated-pathways to promote neuronal differentiation of HUMSCs.

Progesterone promotes neuronal differentiation of human umbilical cord mesenchymal stem cells in culture conditions that mimic the brain microenvironment

In this study, human umbilical cord mesenchymal stem cells from full-term neonates born by vaginal delivery were cultured in medium containing 150 mg/mL of brain tissue extracts from Sprague-Dawley rats (to mimic the brain microenvironment). Immunocytochemical analysis demonstrated that the cells differentiated into neuron-like cells. To evaluate the effects of progesterone as a neurosteroid on the neuronal differentiation of human umbilical cord mesenchymal stem cells, we cultured the cells in medium containing progesterone (0.1, 1, 10 μM) in addition to brain tissue extracts. Reverse transcription-PCR and flow cytometric analysis of neuron specific enolase-positive cells revealed that the percentages of these cells increased significantly following progesterone treatment, with the optimal progesterone concentration for neuron-like differentiation being 1 μM. These results suggest that progesterone can enhance the neuronal differentiation of human umbilical cord mesenchymal stem cells in culture medium containing brain tissue extracts to mimic the brain microenvironment.

Pdx1 and controlled culture conditions induced differentiation of human amniotic fluid-derived stem cells to insulin-producing clusters

This study investigated the differentiation of human amniotic fluid-derived stem cells (hAFSCs) into insulin-producing clusters in vitro. Adenovirally-delivered mouse Pdx1 (Ad-Pdx1) induced human Pdx1 expression in hAFSCs and enhanced the coordinated expression of downstream β-cell markers. When Ad-Pdx1-transduced hAFSCs were sequentially treated with activin A, bFGF and nicotinamide and the culture plate surface coated with poly-l-ornithine, the expression of islet-associated human mRNAs for Pdx1, Pax6, Ngn3 and insulin was increased. C-peptide ELISA confirmed that Ad-Pdx1-transduced hAFSCs processed and secreted insulin in a manner consistent with that pathway in pancreatic β-cells. To sustain the β-cell-like phenotype and investigate the effect of three-dimensional (3D) conformation on the differentiation of hAFSCs, Pdx1-transduced cells were encapsulated in alginate and cultured long-term under serum-free conditions. Over 2 weeks, partially differentiated hAFSC clusters increased in size and increased insulin secretion. Taken together, these data demonstrate that ectopic Pdx1 expression initiates pancreatic differentiation in hAFSCs and that a β-cell-like phenotype can be augmented by culture conditions that mimic the stromal components and 3D geometry associated with pancreatic islets.

Human insulin secreted from insulinogenic xenograft restores normoglycemia in type 1 diabetic mice without immunosuppression

In the present study, we examined the therapeutic potential of human amnion-derived insulin-secreting cells for type 1 diabetes. Human amniotic mesenchymal stem cells (hAMs) were isolated from amnion and cultivated to differentiate into insulin-secreting cells in vitro. After culture in vitro, the differentiated cells (hAM-ISCs) were intensively stained with dithizone and secreted insulin and c-peptide in a high-glucose-dependent manner. They expressed mRNAs of pancreatic cell-related genes, including INS, PDX1, Nkx6-1, NEUROG3, ISL1, NEUROD1, GLUT1, GLUT2, PC1/3, PC2, GCK, PPY, SST, and GC, and were positive for human insulin and c-peptide. Transplantation of hAM-ISCs into the kidneys of mice with streptozotocin-induced diabetes restored body weight and normalized the blood glucose levels, which lasted for 210 days. Only human insulin and c-peptide were detected in the blood of normalized mice after 2 months of transplantation, but little mouse insulin and c-peptide. Removal of graft-bearing kidneys from these mice resulted in causing hyperglycemia again. Human cell-specific gene, hAlu, and human pancreatic cell-specific genes, insulin, PDX1, GLUT1, GLP1R, Nkx6-1, NEUROD1, and NEUROG3, were detected in the graft-bearing kidneys. Colocalization of human insulin and human nuclei antigen was also observed. These results demonstrate that hAMs could differentiate into functional insulin-secreting cells in vitro, and human insulin secreted from hAM-ISCs following transplantation into type 1 diabetic mice could normalize hyperglycemia, overcoming immune rejection for a long period.

Bone marrow and pancreatic islets: an old story with new perspectives

In the past years, in the field of β-cell replacement for diabetes therapy, the easy availability of bone marrow (BM) and the widely consolidated clinical experience in the field of hematology have contributed to the development of strategy to achieve donor-specific transplantation tolerance. Recently, the potential role of BM in diabetes therapy has been reassessed from a different point of view. Diverse groups investigated the contribution of BM cells to β-cell replacement as direct differentiation into insulin-producing cells. More importantly, while direct differentiation is highly unlikely, a wide array of experimental evidences indicates that cells of BM origin are capable of facilitating the survival or the endogenous regeneration of β-cells through an as yet well-defined regeneration process. These new experimental in vitro and in vivo data will expand in the near future the clinical trials involving BM or BM-derived cells to cure both type 1 and type 2 diabetes in humans. In this review we recapitulate the history of use of BM in diabetes therapy and we provide clinically relevant actual information about the participation of BM and BM-derived stem cells in islet cell regeneration processes. Furthermore, new aspects such as employing BM as "feeder tissue" for pancreatic islets and new clinical use of BM in diabetes therapy are discussed.

Development of insulin-producing cells from primitive biologic precursors

PURPOSE OF REVIEW

The differentiation of pluripotent and multipotent stem cells into insulin-producing cells has the potential to create a renewable supply of replacement beta cells with tremendous utility in the treatment of diabetes. The purpose of this review is to summarize recent advancements in the field, with emphasis on the limitations of this technology as it relates to the beta cell.

RECENT FINDINGS

Multiple groups have developed successful in-vitro protocols to differentiate human embryonic stem cells and selected tissue specific stem cells into progenitors capable of insulin production and glucose-stimulated insulin secretion. The resulting cells are immature beta cell-like cells that coexpress multiple islet hormones and lack the full complement of genes necessary for normal function. Protocols that include in-vivo maturation in immune-compromised mice produce cells with a more mature phenotype.

SUMMARY

Although tremendous progress has been made in differentiating stem cells into insulin-producing cells, there is still more research needed to produce a fully functional adult beta cell.

In vitro differentiation of human placenta-derived adherent cells into insulin-producing cells

This study investigated the differentiation of placenta-derived adherent cells (PDACs) into insulin-producing cells (IPCs). PDACs were cultured and the cells characterized by analysis of cell surface markers using flow cytometry. The PDACs were then treated with induction media containing basic fibroblast growth factor (bFGF) and beta-mercaptoethanol (beta-ME). After induction, the presence of IPCs was demonstrated using dithizone staining, and the production of functional insulin was confirmed using immunocytochemistry and an enzyme-linked immunosorbent assay. Expression of the islet-associated genes PDX-1, Insulin 1, Insulin 2 and Glut 2 in the induced cells was measured using a reverse transcription-polymerase chain reaction; PDX-1 was expressed after 7 days of induction and PDX-1, Insulin 1 and Insulin 2 were all detected after 14 days. These results suggest that the placenta could be a new source of stem cells that can be induced to differentiate into IPCs following treatment with media containing bFGF and beta-ME.

The differentiation of human placenta-derived mesenchymal stem cells into dopaminergic cells in vitro

Mesenchymal stem cells (MSCs) constitute an interesting cellular source to promote brain regeneration after Parkinson's disease. MSCs have significant advantages over other stem cell types, and greater potential for immediate clinical application. The aim of this study was to investigate whether MSCs from the human placenta could be induced to differentiate into dopaminergic cells. MSCs from the human placenta were isolated by digestion and density gradient fractionation, and their cell surface glycoproteins were analyzed by flow cytometry. These MSCs were cultured under conditions promoting differetiation into adipocytes and osteoblasts. Using a cocktail that includes basic fibroblast growth factor (bFGF), all trans retinoic acid (RA), ascorbic acid (AA) and 3-isobutyl-1-methylxanthine (IBMX), the MSCs were induced in vitro to become dopamine (DA) neurons. Then, the expression of the mRNA for the Nestin and tyrosine hydroxylase (TH) genes was assayed via RT-PCR. The expression of the Nestin, dopamine transporter (DAT), neuronal nuclear protein (NeuN) and TH proteins was determined via immunofluorescence. The synthesized and secreted DA was determined via ELISA. We found that MSCs from the human placenta exhibited a fibroblastoid morphology. Flow cytometric analyses showed that the MSCs were positive for CD44 and CD29, and negative for CD34, CD45, CD106 and HLA-DR. Moreover, they could be induced into adipocytes and osteocytes. When the MSCs were induced with bFGF, RA, AA and IBMX, they showed a change in morphology to that of neuronal-like cells. The induced cells expressed Nestin and TH mRNA, and the Nestin, DAT, NeuN and TH proteins, and synthesized and secreted DA. Our results suggest that MSCs from the human placenta have the ability to differentiate into dopaminergic cells.

Cytokines inducing bone marrow SCA+ cells migration into pancreatic islet and conversion into insulin-positive cells in vivo

We hypothesize that specific bone marrow lineages and cytokine treatment may facilitate bone marrow migration into islets, leading to a conversion into insulin producing cells in vivo. In this study we focused on identifying which bone marrow subpopulations and cytokine treatments play a role in bone marrow supporting islet function in vivo by evaluating whether bone marrow is capable of migrating into islets as well as converting into insulin positive cells. We approached this aim by utilizing several bone marrow lineages and cytokine-treated bone marrow from green fluorescent protein (GFP) positive bone marrow donors. Sorted lineages of Mac-1⁺, Mac-1⁻, Sca⁺, Sca⁻, Sca⁻/Mac-1⁺ and Sca⁺/Mac-1⁻ from GFP positive mice were transplanted to irradiated C57BL6 GFP negative mice. Bone marrow from transgenic human ubiquitin C promoter GFP (uGFP, with strong signal) C57BL6 mice was transplanted into GFP negative C57BL6 recipients. After eight weeks, migration of GFP positive donor' bone marrow to the recipient's pancreatic islets was evaluated as the percentage of positive GFP islets/total islets. The results show that the most effective migration comes from the Sca⁺/Mac⁻ lineage and these cells, treated with cytokines for 48 hours, were found to have converted into insulin positive cells in pancreatic islets in vivo. This study suggests that bone marrow lineage positive cells and cytokine treatments are critical factors in determining whether bone marrow is able to migrate and form insulin producing cells in vivo. The mechanisms causing this facilitation as well as bone marrow converting to pancreatic beta cells still need to be investigated.

Derivation of neural stem cells from mesenchymal stemcells: evidence for a bipotential stem cell population

Neural stem cell (NSC) transplantation has been proposed as a future therapy for neurodegenerative disorders. However, NSC transplantation will be hampered by the limited number of brain donors and the toxicity of immunosuppressive regimens that might be needed with allogeneic transplantation. These limitations may be avoided if NSCs can be generated from clinically accessible sources, such as bone marrow (BM) and peripheral blood samples, that are suitable for autologous transplantation. We report here that NSCs can be generated from human BM-derived mesenchymal stem cells (MSCs). When cultured in NSC culture conditions, 8% of MSCs were able to generate neurospheres. These MSC-derived neurospheres expressed characteristic NSC antigens, such as nestin and musashi-1, and were capable of self-renewal and multilineage differentiation into neurons, astrocytes, and oligodendrocytes. Furthermore, when these MSC-derived neurospheres were cocultured with primary astrocytes, they differentiate into neurons that possess both dendritic and axonal processes, form synapses, and are able to fire tetrodotoxin-sensitive action potentials. When these MSC-derived NSCs were switched back to MSC culture conditions, a small fraction of NSCs (averaging 4-5%) adhered to the culture flasks, proliferated, and displayed the morphology of MSCs. Those adherent cells expressed the characteristic MSC antigens and regained the ability to differentiate into multiple mesodermal lineages. Data presented in this study suggest that MSCs contain a small fraction (averaging 4-5%) of a bipotential stem cell population that is able to generate either MSCs or NSCs depending on the culture conditions.

Promoting ectopic pancreatic fates: pancreas development and future diabetes therapies

Diabetes is a disease that could be treated more effectively with a better understanding of pancreas development. This review examines the role of master regulator genes driving crucial steps in pancreas development, from foregut specification to differentiation of the five endocrine cell types. The roles of Pdx1, Ptf1a, and Ngn3 are particularly examined as they are both necessary and sufficient for promoting pancreatic cell fates (Pdx1, Ptf1a) and endocrine cell development (Ngn3). The roles of Arx and Pax4 are studied as they compose part of the regulatory mechanism balancing development of different types of endocrine cells within the iselts and promote the development of alpha/PP and beta/delta cell progenitors, respectively. The roles of the aforementioned genes, and the consequences of misexpression of them for functionality of the pancreas, are examined through recent studies in model organisms, particularly Xenopus and zebrafish. Recent developments in cell replacement therapy research are also covered, concentrating on stem cell research (coaxing both adult and embryonic stem cells toward a beta cell fate) and transdifferentiation (generating beta cells from other differentiated cell types).