Ex vivo expansion of a hematopoietic stem cell on a murine stromal cell by 3D micro-pillar device

Shear stress promotes differentiation of stem cells from human exfoliated deciduous teeth into endothelial cells via the downstream pathway of VEGF-Notch signaling

Effects of shear stress on endotheliaxl differentiation of stem cells from human exfoliated deciduous teeth (SHEDs) were investigated. SHEDs were treated with shear stress, then reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to analyse the mRNA expression of arterial markers and western blot analysis was performed to analyse protein expression of angiogenic markers. Additionally, in vitro matrigel angiogenesis assay was performed to evaluate vascular-like structure formation. The secreted protein expression levels of the vascular endothelial growth factor (VEGF) of SHEDs after shear stress was also quantified using corresponding ELISA kits. Untreated SHEDs seeded on Matrigel cannot form vessel-like structures at any time points, whereas groups treated with shear stress formed a few vessel-like structures at 4, 8 and 12 h. When SHEDs were treated with EphrinB2-siRNA for 24, the capability of vessel-like structure formation was suppressed. After being treated with shear stress, the expression of VEGF, VEGFR2, DLL4, Notch1, EphrinB2, Hey1 and Hey2 (arterial markers) gene expression was significantly upregulated, moreover, the protein levels of VEGFR2, EphrinB2, CD31, Notch1, DLL4, Hey1, and Hey2 were also significantly up-regulated. Both the mRNA and protein expression levels of EphB4 (venous marker) were downregulated. The average VEGF protein concentration in supernatants secreted by shear stress treated SHEDs groups increased significantly. In conclusion, shear stress was able to induce arterial endothelial differentiation of stem cells from human exfoliated deciduous teeth, and VEGF-DLL4/Notch‑EphrinB2 signaling was involved in this process.

Features of Microsystems for Cultivation and Characterization of Stem Cells with the Aim of Regenerative Therapy

Stem cells have infinite potential for regenerative therapy thanks to their advantageous ability which is differentiable to requisite cell types for recovery and self-renewal. The microsystem has been proved to be more helpful to stem cell studies compared to the traditional methods, relying on its advantageous feature of mimicking in vivo cellular environments as well as other profitable features such as minimum sample consumption for analysis and multiprocedures. A wide variety of microsystems were developed for stem cell studies; however, regenerative therapy-targeted applications of microtechnology should be more emphasized and gain more attractions since the regenerative therapy is one of ultimate goals of biologists and bioengineers. In this review, we introduce stem cell researches harnessing well-known microtechniques (microwell, micropattern, and microfluidic channel) in view point of physical principles and how these systems and principles have been implemented appropriately for characterizing stem cells and finding possible regenerative therapies. Biologists may gain information on the principles of microsystems to apply them to find solutions for their current challenges, and engineers may understand limitations of the conventional microsystems and find new chances for further developing practical microsystems. Through the well combination of engineers and biologists, the regenerative therapy-targeted stem cell researches harnessing microtechnology will find better suitable treatments for human disorders.

Osteogenic differentiation of stem cells from human exfoliated deciduous teeth on poly(ε-caprolactone) nanofibers containing strontium phosphate

Mimicking the architecture of the extracellular matrix is an effective strategy for tissue engineering. Composite nanofibers similar to natural bone structure can be prepared via an electrospinning technique and used in biomedical applications. Stem cells from human exfoliated deciduous teeth (SHEDs) can differentiate into multiple cell lineages, such as cells that are alternative sources of stem cells for tissue engineering. Strontium has important functions in bone remodeling; for example, this element can simulate bone formation and decrease bone resorption. Incorporating strontium phosphate into nanofibers provides a potential material for bone tissue engineering. This study investigated the potential of poly(ε-caprolactone) (PCL) nanofibers coated or blended with strontium phosphate for the osteogenic differentiation of SHEDs. Cellular morphology and MTT assay revealed that nanofibers effectively support cellular attachment, spreading, and proliferation. Strontium-loaded PCL nanofibers exhibited higher expressions of collagen type I, alkaline phosphatase, biomineralization, and bone-related genes than pure PCL nanofibers during the osteogenic differentiation of SHEDs. This study demonstrated that strontium can be an effective inducer of osteogenesis for SHEDs. Understanding the function of bioceramics (such as strontium) is useful in designing and developing strategies for bone tissue engineering.

Osteogenic differentiation and mineralization of human exfoliated deciduous teeth stem cells on modified chitosan scaffold

Stem cells from human exfoliated deciduous teeth (SHEDs) have been considered as alternative sources of adult stem cells in tissue engineering because of their potential to differentiate into multiple cell lineages. Strontium has an important function in bone remodeling because it can simulate bone formation and decrease bone resorption. In this study, the effects of strontium phosphate on the osteogenic differentiation of SHEDs were investigated. Strontium phosphate was found to enhance the osteogenic differentiation of SHEDs with up-regulated osteoblast-related gene expression. The proliferation of SHEDs was slightly inhibited by chitosan scaffolds; however, type-I collagen expression, alkaline phosphatase activity, and calcium deposition on chitosan scaffolds containing strontium were significantly enhanced. Furthermore, cells seeded in a 3D scaffold under dynamic culture at an optimal fluid rate might enhance cellular differentiation than static culture in osteoblastic gene expression. This experiment might provide a useful cell resource and dynamic 3D culture for tissue engineering and bone repair.

Precise control of cell adhesion by combination of surface chemistry and soft lithography

The adhesion of cells on an extracellular matrix (ECM) (in vivo) or the surfaces of materials (in vitro) is a prerequisite for most cells to survive. The rapid growth of nano/microfabrication and biomaterial technologies has provided new materials with excellent surfaces with specific, desirable biological interactions with their surroundings. On one hand, the chemical and physical properties of material surfaces exert an extensive influence on cell adhesion, proliferation, migration, and differentiation. On the other hand, material surfaces are useful for fundamental cell biology research and tissue engineering. In this Review, an overview will be given of the chemical and physical properties of newly developed material surfaces and their biological effects, as well as soft lithographic techniques and their applications in cell biology research. Recent advances in the manipulation of cell adhesion by the combination of surface chemistry and soft lithography will also be highlighted.

Fabrication of micropillar substrates using replicas of alpha-particle irradiated and chemically etched PADC films

We proposed a simple method to fabricate micropillar substrates. Polyallyldiglycol carbonate (PADC) films were irradiated by alpha particles and then chemically etched to form a cast with micron-scale spherical pores. A polydimethylsiloxane (PDMS) replica of this PADC film gave a micropillar substrate with micron-scale spherical pillars. HeLa cells cultured on such a micropillar substrate had significantly larger percentage of cells entering S-phase, attached cell numbers and cell spreading areas.