Generating mESC-derived insulin-producing cell lines through an intermediate lineage-restricted progenitor line

In vitro generation of transplantable insulin-producing cells from canine adipose-derived mesenchymal stem cells

Canine mesenchymal stem cells (cMSCs) have potential applications for regenerative therapy, including the generation of insulin-producing cells (IPCs) for studying and treating diabetes. In this study, we established a useful protocol for generating IPCs from canine adipose mesenchymal stem cells (cAD-MSCs). Subsequently, in vitro preservation of pluronic F127-coated alginate (ALGPA)-encapsulated cAD-MSC-derived IPCs was performed to verify ready-to-use IPCs. IPCs were induced from cAD-MSCs with the modulated three-stepwise protocol. The first step of definitive endoderm (DE) induction showed that the cooperation of Chir99021 and Activin A created the effective production of Sox17-expressed DE cells. The second step for pancreatic endocrine (PE) progenitor induction from DE indicated that the treatment with taurine, retinoic acid, FGF2, EGF, TGFβ inhibitor, dorsomorphin, nicotinamide, and DAPT showed the significant upregulation of the pancreatic endocrine precursor markers Pdx1 and Ngn3. The last step of IPC production, the combination of taurine, nicotinamide, Glp-1, forskolin, PI3K inhibitor, and TGFβ inhibitor, yielded efficiently functional IPCs from PE precursors. Afterward, the maintenance of ALGPA-encapsulated cAD-MSC-derived IPCs with VSCBIC-1, a specialized medium, enhanced IPC properties. Conclusion, the modulated three-stepwise protocol generates the functional IPCs. Together, the encapsulation of cAD-MSC-derived IPCs and the cultivation with VSCBIC-1 enrich the maturation of generated IPCs.

Mesenchymal stem cell: an efficient mass producer of exosomes for drug delivery

Advances in biomedical research have generated an unprecedented number of potential targets for therapeutic intervention to treat disease or delay disease progression. Unfortunately, many of these targets are not druggable as they are intracellular, present in many cell types, poorly soluble or rapidly inactivated. Although synthetic drug vehicles have successfully circumvented many of these problems, natural particulates such as exosomes that intrinsically possess many attributes of a drug delivery vehicle are highly attractive as potentially better alternatives. Of the cell types known to produce exosomes, the readily available proliferative, immunosuppressive and clinically tested human mesenchymal stem cell (MSC) is the most prolific producer. Its exosomes are therapeutic in animal model of disease and exhibit immunosuppressive activity. The quality and quantity of exosome production is not compromised by immortalization to create a permanent MSC cell line. Therefore, MSC is well suited for mass production of exosomes that are ideal for drug delivery.

Toward personalized cell therapies by using stem cells: seven relevant topics for safety and success in stem cell therapy

Stem cells, both embryonic and adult, due to the potential for application in tissue regeneration have been the target of interest to the world scientific community. In fact, stem cells can be considered revolutionary in the field of medicine, especially in the treatment of a wide range of human diseases. However, caution is needed in the clinical application of such cells and this is an issue that demands more studies. This paper will discuss some controversial issues of importance for achieving cell therapy safety and success. Particularly, the following aspects of stem cell biology will be presented: methods for stem cells culture, teratogenic or tumorigenic potential, cellular dose, proliferation, senescence, karyotyping, and immunosuppressive activity.

High glucose predisposes gene expression and ERK phosphorylation to apoptosis and impaired glucose-stimulated insulin secretion via the cytoskeleton

Chronic high glucose (HG) inflicts glucotoxicity on vulnerable cell types such as pancreatic β cells and contributes to insulin resistance and impaired insulin secretion in diabetic patients. To identify HG-induced cellular aberrations that are candidate mediators of glucotoxicity in pancreatic β cells, we analyzed gene expression in ERoSHK6, a mouse insulin-secreting cell line after chronic HG exposure (six-day exposure to 33.3 mM glucose). Chronic HG exposure which reduced glucose-stimulated insulin secretion (GSIS) increased transcript levels of 185 genes that clustered primarily in 5 processes namely cellular growth and proliferation; cell death; cellular assembly and organization; cell morphology; and cell-to-cell signaling and interaction. The former two were validated by increased apoptosis of ERoSHK6 cells after chronic HG exposure and reaffirmed the vulnerability of β cells to glucotoxicity. The three remaining processes were partially substantiated by changes in cellular morphology and structure, and instigated an investigation of the cytoskeleton and cell-cell adhesion. These studies revealed a depolymerized actin cytoskeleton that lacked actin stress fibers anchored at vinculin-containing focal adhesion sites as well as loss of E-cadherin-mediated cell-cell adherence after exposure to chronic HG, and were concomitant with constitutive ERK1/2 phosphorylation that was refractory to serum and glucose deprivation. Although inhibition of ERK phosphorylation by PD98059 promoted actin polymerization, it increased apoptosis and GSIS impairment. These findings suggest that ERK phosphorylation is a proximate regulator of cellular processes targeted by chronic HG-induced gene expression and that dynamic actin polymerization and depolymerization is important in β cell survival and function. Therefore, chronic HG alters gene expression and signal transduction to predispose the cytoskeleton towards apoptosis and GSIS impairment.

Combined transfection of the three transcriptional factors, PDX-1, NeuroD1, and MafA, causes differentiation of bone marrow mesenchymal stem cells into insulin-producing cells

Aims. The goal of cell transcription for treatment of diabetes is to generate surrogate β-cells from an appropriate cell line. However, the induced replacement cells have showed less physiological function in producing insulin compared with normal β-cells. Methods. Here, we report a procedure for induction of insulin-producing cells (IPCs) from bone marrow murine mesenchymal stem cells (BM-mMSCs). These BM-mMSCs have the potential to differentiate into insulin-producing cells when a combination of PDX-1 (pancreatic and duodenal homeobox-1), NeuroD1 (neurogenic differentiation-1), and MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homolog A) genes are transfected into them and expressed in these cells. Results. Insulin biosynthesis and secretion were induced in mMSCs into which these three genes have been transfected and expressed. The amount of induced insulin in the mMSCs which have been transfected with the three genes together is significantly higher than in those mMSCs that were only transfected with one or two of these three genes. Transplantation of the transfected cells into mice with streptozotocin-induced diabetes results in insulin expression and the reversal of the glucose challenge. Conclusions. These findings suggest major implications for cell replacement strategies in generation of surrogate β-cells for the treatment of diabetes.

Immunological applications of stem cells in type 1 diabetes

Current approaches aiming to cure type 1 diabetes (T1D) have made a negligible number of patients insulin-independent. In this review, we revisit the role of stem cell (SC)-based applications in curing T1D. The optimal therapeutic approach for T1D should ideally preserve the remaining β-cells, restore β-cell function, and protect the replaced insulin-producing cells from autoimmunity. SCs possess immunological and regenerative properties that could be harnessed to improve the treatment of T1D; indeed, SCs may reestablish peripheral tolerance toward β-cells through reshaping of the immune response and inhibition of autoreactive T-cell function. Furthermore, SC-derived insulin-producing cells are capable of engrafting and reversing hyperglycemia in mice. Bone marrow mesenchymal SCs display a hypoimmunogenic phenotype as well as a broad range of immunomodulatory capabilities, they have been shown to cure newly diabetic nonobese diabetic (NOD) mice, and they are currently undergoing evaluation in two clinical trials. Cord blood SCs have been shown to facilitate the generation of regulatory T cells, thereby reverting hyperglycemia in NOD mice. T1D patients treated with cord blood SCs also did not show any adverse reaction in the absence of major effects on glycometabolic control. Although hematopoietic SCs rarely revert hyperglycemia in NOD mice, they exhibit profound immunomodulatory properties in humans; newly hyperglycemic T1D patients have been successfully reverted to normoglycemia with autologous nonmyeloablative hematopoietic SC transplantation. Finally, embryonic SCs also offer exciting prospects because they are able to generate glucose-responsive insulin-producing cells. Easy enthusiasm should be mitigated mainly because of the potential oncogenicity of SCs.

Elimination of tumorigenic stem cells from differentiated progeny and selection of definitive endoderm reveals a Pdx1+ foregut endoderm stem cell lineage

Embryonic stem cell (ESC) derivatives offer promise for generating clinically useful tissues for transplantation, yet the specter of producing tumors in patients remains a significant concern. We have developed a simple method that eliminates the tumorigenic potential from differentiated ESC cultures of murine and human origin while purifying lineage-restricted, definitive endoderm-committed cells. A three-stage scheme utilizing magnetic bead sorting and specific antibodies to remove undifferentiated ESCs and extraembryonic endoderm cells, followed by positive selection of definitive endoderm cells on the basis of epithelial cell adhesion molecule (EpCAM) expression, was used to isolate a population of EpCAM(+)SSEA1(-)SSEA3(-) cells. Sorted cells do not form teratomas after transplantation into immunodeficient mice, but display gene and protein expression profiles indicative of definitive endoderm cells. Sorted cells could be subsequently expanded in vitro and further differentiated to express key pancreas specification proteins. In vivo transplantation of sorted cells resulted in small, benign tissues that uniformly express PDX1. These studies describe a straightforward method without genetic manipulation that eliminates the risk of teratoma formation from ESC differentiated derivatives. Significantly, enriched populations isolated by this method appear to be lineage-restricted definitive endoderm cells with limited proliferation capacity.

Delineating biological pathways unique to embryonic stem cell-derived insulin-producing cell lines from their noninsulin-producing progenitor cell lines

To identify unique biochemical pathways in embryonic stem cell-derived insulin-producing cells as potential therapeutic targets to prevent or delay beta-cell dysfunction or death in diabetic patients, comparative genome-wide gene expression studies of recently derived mouse insulin-producing cell lines and their progenitor cell lines were performed using microarray technology. Differentially expressed genes were functionally clustered to identify important biochemical pathways in these insulin-producing cell lines. Biochemical or cellular assays were then performed to assess the relevance of these pathways to the biology of these cells. A total of 185 genes were highly expressed in the insulin-producing cell lines, and computational analysis predicted the pentose phosphate pathway (PPP), clathrin-mediated endocytosis, and the peroxisome proliferator-activated receptor (PPAR) signaling pathway as important pathways in these cell lines. Insulin-producing ERoSHK cells were more resistant to hydrogen peroxide (H(2)O(2))-induced oxidative stress. Inhibition of PPP by dehydroepiandrosterone and 6-aminonicotinamide abrogated this H(2)O(2) resistance with a concomitant decrease in PPP activity as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Clathrin-mediated endocytosis, which is essential in maintaining membrane homeostasis in secreting cells, was up-regulated by glucose in ERoSHK but not in their progenitor ERoSH cells. Its inhibition by chlorpromazine at high glucose concentration was toxic to the cells. Troglitazone, a PPARG agonist, up-regulated expression of Ins1 and Ins2 but not Glut2. Gene expression analysis has identified the PPP, clathrin-mediated endocytosis, and the PPAR signaling pathway as the major delineating pathways in these insulin-producing cell lines, and their biological relevance was confirmed by biochemical and cellular assays.

Effects of sodium butyrate on the differentiation of pancreatic and hepatic progenitor cells from mouse embryonic stem cells

Recently significant progress has been made in differentiating embryonic stem (ES) cells toward pancreatic cells. However, little is known about the generation and identification of pancreatic progenitor cells from ES cells. Here we explored the influence of sodium butyrate on pancreatic progenitor differentiation, and investigated the different effects of sodium butyrate on pancreatic and hepatic progenitor formation. Our results indicated that different concentration and exposure time of sodium butyrate led to different differentiating trends of ES cells. A relatively lower concentration of sodium butyrate with shorter exposure time induced more pancreatic progenitor cell formation. When stimulated by a higher concentration and longer exposure time of sodium butyrate, ES cells differentiated toward hepatic progenitor cells rather than pancreatic progenitor cells. These progenitor cells could further mature into pancreatic and hepatic cells with the supplement of exogenous inducing factors. The resulting pancreatic cells expressed specific markers such as insulin and C-peptide, and were capable of insulin secretion in response to glucose stimulation. The differentiated hepatocytes were characterized by the expression of a number of liver-associated genes and proteins, and had the capability of glycogen storage. Thus, the current study demonstrated that sodium butyrate played different roles in inducing ES cells toward pancreatic or hepatic progenitor cells. These progenitor cells could be further induced into mature pancreatic cells and hepatocytes. This finding may facilitate the understanding of pancreatic and hepatic cell differentiation from ES cells, and provide a potential source of transplantable cells for cell-replacement therapies.