Dynamic Behavior and Spontaneous Differentiation of Mouse Embryoid Bodies on Hydrogel Substrates of Different Surface Charge and Chemical Structures

A new avenue to the synthesis of GAG-mimicking polymers highly promoting neural differentiation of embryonic stem cells

A new strategy for the fabrication of glycosaminoglycan (GAG) analogs with high bioactivities was proposed by copolymerizing the sulfonated unit and the glyco unit, ‘splitted’ from the sulfated saccharide building blocks of GAGs.

The effect of electrically charged polyion complex nanoparticle-coated surfaces on adipose-derived stromal progenitor cell behaviour

Surface characteristics of biomaterials such as wettability, rigidity, roughness, and electrical charge affect the fate of transplanted cells such as progenitor cells or stem cells for use in regenerative medicine. Of these, the effects of surface electrical charges on cellular behaviour such as adhesion, proliferation, and differentiation are not well understood. We prepared precisely charged culture surfaces ranging from -28 mV to +21 mV, simply by surface deposition of polyion complex nanoparticles prepared by mixing a positively charged thermoresponsive homopolymer, poly(N,N-dimethylaminoethyl methacrylate), with negatively charged plasmid DNA at various charge ratios. Drastic morphological changes of adipose-derived vascular progenitor cells were generated on the positively charged surface of organized forms at +19 mV. Capillary-like networks or single aggregates of these cells were selectively created depending on cell seeding density. Our findings offer new insights that may aid develop stem cell-processing techniques for use in regenerative medicine.

Hydrogels as feeder-free scaffolds for long-term self-renewal of mouse induced pluripotent stem cells

Expanding undifferentiated induced pluripotent stem (iPS) cells in vitro is a basic requirement for application of iPS cells in both fundamental research and clinical regeneration. In this study, we intended to establish a simple, low cost and efficient method for the long-term self-renewal of mouse induced pluripotent stem (miPS) cells without using feeder-cells and adhesive proteins. Three scaffolds were selected for the long-term subculture of miPS cells over two months starting from passages 14 to 29: 1) a gelatin coated polystyrene (Gelatin-PS) that is a widely used scaffold for self-renewal of mouse embryonic stem (mES) cells; 2) a neutral hydrogel poly(N,N-dimethylacrylamide) (PDMAAm); and 3) a negatively charged hydrogel poly(2-acrylamido-2-methyl-propane sulfonic acid sodium salt) (PNaAMPS). Each passaged miPS cells on these scaffolds were cryopreserved successfully and the revived cells showed high viability and proliferation. The passaged miPS cells maintained a high undifferentiated state on all three scaffolds and a high level of pluripotency by expressing differentiation markers in vitro and forming teratomas in SCID mice with derivatives of all three germ layers. Compared to Gelatin-PS, the two hydrogels exhibited much better self-renewal performance in terms of high proliferation rate and level of expression of undifferentiated gene markers as well as efficiency in pluripotent teratoma formation. Furthermore, the PNaAMPS hydrogel demonstrated a slightly higher efficiency and simpler operation of cell expansion than the PDMAAm hydrogel. To conclude, PNaAMPS hydrogel is an excellent feeder-free scaffold because of its simplicity, low cost and high efficiency in expanding a large number of miPS cells in vitro.

Generation, characterization, and potential therapeutic applications of cardiomyocytes from various stem cells

Heart failure is one of the leading causes of death worldwide. Myocardial cell transplantation emerges as a novel therapeutic strategy for heart failure, but this approach has been hampered by severe shortage of human cardiomyocytes. We have recently induced mouse embryonic stem cells to differentiate into embryoid bodies and eventually, cardiomyocytes. Here, we address recent advancements in cardiomyocyte differentiation from cardiac stem cells and pluripotent stem cells. We highlight the methodologies, using growth factors, endoderm-like cell cocultures, small molecules, and biomaterials, in directing the differentiation of pluripotent stem cells into cardiomyocytes. The characterization and identification of pluripotent stem cell-derived cardiomyocytes by morphological, phenotypic, and functional features are also discussed. Notably, increasing evidence demonstrates that cardiomyocytes may be generated from the stem cells of several tissues outside the cardiovascular system, including skeletal muscles, bone marrow, testes, placenta, amniotic fluid, and adipose tissues. We further address the potential applications of cardiomyocytes derived from various kinds of stem cells. The differentiation of stem cells into functional cardiomyocytes, especially from an extra-cardiac stem cell source, would circumvent the scarcity of heart donors and human cardiomyocytes, and, most importantly, it would offer an ideal and promising cardiomyocyte source for cell therapy and tissue engineering in treating heart failure.