In vitro differentiation potential of human embryonic versus adult stem cells

The human gastrointestinal tract, a potential autologous neural stem cell source

Stem cell therapies seem to be an appropriate tool for the treatment of a variety of diseases, especially when a substantial cell loss leads to a severe clinical impact. This is the case in most neuronal cell losses. Unfortunately, adequate neural stem cell sources are hard to find and current alternatives, such as induced programmed stem cells, still have incalculable risks. Evidence of neurogenesis in the adult human enteric nervous system brought up a new perspective. In humans the appendix harbors enteric neuronal tissue and is an ideal location where the presence of neural stem cells is combined with a minimal invasive accessibility. In this study appendices from adults and children were investigated concerning their neural stem cell potential. From each appendix tissue samples were collected, and processed for immunohistochemistry or enteric neural progenitor cell generation. Free-floating enteric neurospheres (EnNS's) could be generated after 6 days in vitro. EnNS's were either used for transplantation into rat brain slices or differentiation experiments. Both transplanted spheres and control cultures developed an intricate network with glia, neurons and interconnecting fibers, as seen in primary enteric cultures before. Neuronal, glial and neural stem cell markers could be identified both in vitro and in vivo by immunostaining. The study underlines the potential of the enteric nervous system as an autologous neural stem cell source. Using the appendix as a potential target opens up a new perspective that might lead to a relatively unproblematic harvest of neural stem cells.

Hepatogenic differentiation of human mesenchymal stem cells from peritoneal adipose tissue

Backgrounds/Aims

It has been reported that functional hepatogenic differentiation has the possibility to occur in subcutaneous adipose tissue-derived stem cells. However, no studies have investigated whether the adipose tissue-driven stem cells present in various body parts differ according to hepatogenic differentiations. In this study, stem cells were separated from body visceral fat and abdominal subcutaneous adipose tissue, and cultured, and then hepatogenic differentiation was induced. We aim to investigate the possibilities and aspects of hepatogenic differentiations within the two types of fat cells.

Methods

Omental fat tissues were obtained as visceral fat and abdominal subcutaneous adipose tissues were obtained from patients who had suction-assisted lipectomy. Stem cells were separated from the obtained fat tissues, and then, hepatogenic differentiation was carried out by utilizing 2-step differentiation protocols.

Results

After the differentiation, two types of cultured cells that showed the similar neuron-like shapes were changed to cuboidal shapes and included several binucleated cells which could be characteristics of mature hepatocytes. We confirmed that hepatocyte specific genes and proteins such as albumin and CYP3A4 were being expressed. By utilizing the ELISA test, we were able to observe that the albumin was secreted into the culture fluids in both cells. After completing the differentiation, we observed the presence of the hepatocyte specific properties by confirming glycogen storage within the cells and the ICG reagent uptake.

Conclusions

We confirmed that hepatogenic differentiation was possible to occur in the omental fat as well as subcutaneous adipose tissue.

Evaluation of silk biomaterials in combination with extracellular matrix coatings for bladder tissue engineering with primary and pluripotent cells

Silk-based biomaterials in combination with extracellular matrix (ECM) coatings were assessed as templates for cell-seeded bladder tissue engineering approaches. Two structurally diverse groups of silk scaffolds were produced by a gel spinning process and consisted of either smooth, compact multi-laminates (Group 1) or rough, porous lamellar-like sheets (Group 2). Scaffolds alone or coated with collagen types I or IV or fibronectin were assessed independently for their ability to support attachment, proliferation, and differentiation of primary cell lines including human bladder smooth muscle cells (SMC) and urothelial cells as well as pluripotent cell populations, such as murine embryonic stem cells (ESC) and induced pluripotent stem (iPS) cells. AlamarBlue evaluations revealed that fibronectin-coated Group 2 scaffolds promoted the highest degree of primary SMC and urothelial cell attachment in comparison to uncoated Group 2 controls and all Group 1 scaffold variants. Real time RT-PCR and immunohistochemical (IHC) analyses demonstrated that both fibronectin-coated silk groups were permissive for SMC contractile differentiation as determined by significant upregulation of α-actin and SM22α mRNA and protein expression levels following TGFβ1 stimulation. Prominent expression of epithelial differentiation markers, cytokeratins, was observed in urothelial cells cultured on both control and fibronectin-coated groups following IHC analysis. Evaluation of silk matrices for ESC and iPS cell attachment by alamarBlue showed that fibronectin-coated Group 2 scaffolds promoted the highest levels in comparison to all other scaffold formulations. In addition, real time RT-PCR and IHC analyses showed that fibronectin-coated Group 2 scaffolds facilitated ESC and iPS cell differentiation toward both urothelial and smooth muscle lineages in response to all trans retinoic acid as assessed by induction of uroplakin and contractile gene and protein expression. These results demonstrate that silk scaffolds support primary and pluripotent cell responses pertinent to bladder tissue engineering and that scaffold morphology and fibronectin coatings influence these processes.

The histone methyltransferase inhibitor BIX01294 enhances the cardiac potential of bone marrow cells

Bone marrow (BM) has long been considered a potential stem cell source for cardiac repair due to its abundance and accessibility. Although previous investigations have generated cardiomyocytes from BM, yields have been low, and far less than produced from ES or induced pluripotent stem cells (iPSCs). Since differentiation of pluripotent cells is difficult to control, we investigated whether BM cardiac competency could be enhanced without making cells pluripotent. From screens of various molecules that have been shown to assist iPSC production or maintain the ES cell phenotype, we identified the G9a histone methyltransferase inhibitor BIX01294 as a potential reprogramming agent for converting BM cells to a cardiac-competent phenotype. BM cells exposed to BIX01294 displayed significantly elevated expression of brachyury, Mesp1, and islet1, which are genes associated with embryonic cardiac progenitors. In contrast, BIX01294 treatment minimally affected ectodermal, endodermal, and pluripotency gene expression by BM cells. Expression of cardiac-associated genes Nkx2.5, GATA4, Hand1, Hand2, Tbx5, myocardin, and titin was enhanced 114, 76, 276, 46, 635, 123, and 5-fold in response to the cardiogenic stimulator Wnt11 when BM cells were pretreated with BIX01294. Immunofluorescent analysis demonstrated that BIX01294 exposure allowed for the subsequent display of various muscle proteins within the cells. The effect of BIX01294 on the BM cell phenotype and differentiation potential corresponded to an overall decrease in methylation of histone H3 at lysine9, which is the primary target of G9a histone methyltransferase. In summary, these data suggest that BIX01294 inhibition of chromatin methylation reprograms BM cells to a cardiac-competent progenitor phenotype.

Label-free detection of surface markers on stem cells by oblique-incidence reflectivity difference microscopy

Conventional fluorescence microscopy is routinely used to detect cell surface markers through fluorophore-conjugated antibodies. However, fluorophore-conjugation of antibodies alters binding properties such as strength and specificity of the antibody in often uncharacterized ways. Here we present a method using an oblique-incidence reflectivity difference (OI-RD) microscope for label-free, real-time detection of cell surface markers, and apply it to analysis of stage-specific embryonic antigen 1 (SSEA1) on stem cells. Mouse stem cells express SSEA1 on their surfaces, and the level of SSEA1 decreases when the cells start to differentiate. In this study, we immobilized mouse stem cells and non-stem cells (control) on a glass surface as a microarray and reacted the cell microarray with unlabeled SSEA1 antibodies. By monitoring the reaction with an OI-RD microscope in real time, we confirmed that the SSEA1 antibodies bind only to the surface of the stem cells and not to the surface of non-stem cells. From the binding curves, we determined the equilibrium dissociation constant (Kd) of the antibody with the SSEA1 markers on the stem cell surface. Thus, the OI-RD microscope can be used to detect binding affinities between cell surface markers and unlabeled antibodies bound to the cells; this information could be useful for determination of stem cell stages.