There are many dystrophies related corneal endothelium resulting in edema, loss of transparency and blindness, finally. Currently, transplantation is only surgical treatment for patients with these corneal endothelial dystrophies, however, the limitation of transplantation is the absolute deficiency of donor cornea. Very recently, to overcome this issue of limited supply of donor cornea, regenerative medicine including stem cell therapy and tissue engineering has been widely attempted and success for human clinical trial.
In this review, recent advances for the regeneration of corneal endothelial cell (CEnC) as (1)isolation and culture methods of CEnC for the somatic cell source, (2)stem cell source for CEnC as embryonic, induce pluripotent stem cell (iPS) and adult stem cell, (3)tissue engineering techniques as cell sheet engineering and development of scaffold materials and finally (4)the application of silk as a biomaterial for cornea by our laboratory have been introduced.

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Restoration of damaged tissues and organs requires precise control of cellular processes at the molecular level. Synthetic biology offers genetic tools that can be used to program the molecular biology of the cell, thereby potentially overcoming the various challenges hampering contemporary tissue engineering applications.

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Scaffold, along with seed cells and microenvironment, is an essential component of tissue engineering, and plays an important role in engineered tissue regeneration. Fibrous scaffold is an important part of scaffold materials due to its ability to mimic the structure of native extracellular matrix. With the advancement of materials science and related techniques, fibers can be modified either chemically or physically to gain special physicochemical and biological properties that can provide an artificial niche environment for cell adhesion, proliferation and differentiation and ultimately lead to tissue regeneration. This paper reviews recent advances in the preparation and the application of fibrous scaffold for engineered tissue regeneration.

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Platelet lysate (PL) has been increasingly explored in tissue engineering and regenerative medicine fields as a natural source of growth factors and/or as a support for cell growth and differentiation. Despite its tremendous potential, when used as tridimensional scaffolding systems, PL presents an inherent fragility and fast dissolution which hinders its application. The main objective of this work was to develop novel and robust PL-based membranes, crosslinked with genipin, for tissue engineering purposes. The membranes prepared present unique physical and mechanical properties, which indicate that these structures might be used in a vast range of applications. These PL-based structures present a high water uptake and stability over time. Overall, the developed membranes demonstrated a positive in vitro biological response as they were able to support and promote the adhesion and proliferation of human adipose derived stem cells. In addition to their role as supportive matrices for cell culture, the proposed membranes may simultaneously act as a growth factor controlled delivery systems, and thus hold great potential in several approaches for the regeneration of tissues.

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The objective of this study is to prepare biodegradable iron oxide nanoparticles with bioabsorbable gelatin. Nano-size gelatin composites with well-dispersed structure of ultra-small iron oxide nanoparticles within a gelatin nanoparticle were prepared by a micro-emulsion method. The gelatin iron oxide nanoparticles prepared were degraded with time in 20 mM citric acid buffer solution at pH 4.5, in remarked contrast to gelatin iron oxide nanoparticles prepared by the conventional co-precipitation method. When co-cultured with human bone marrow-derived mesenchymal stem cells, the gelatin iron oxide nanoparticles were internalized into cells and degraded with time intracellularly. The biodegradable gelatin iron oxide nanoparticles showed the T2-weighted signals of magnetic resonance imaging.

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To study the ultrastructure of regenerated bone, the ectopically formed bone induced by gelatin hydrogels incorporating bone morphogenetic protein 2 (BMP-2) was evaluated through transmission electron microscopic (TEM) analyses including bright field electron imaging, selected area diffraction (SAD) imaging, and dark field electron imaging. After 2 weeks of implantation, ectopic bone induction was apparent at Wistar rat thigh muscles receiving the hydrogels incorporating BMP-2 through soft X-ray observation. The specimens for TEM study were prepared with an anhydrous method using ethylene glycol to maintain the structure of hydroxyapatite crystals. TEM observation of unstained ectopic bone cross-sections showed that electron dense substances were deposited on the gap zone of collagen fibers (intrafibrillar crystallites), while needle-like electron dense substances were observed in the intermolecular space of collagen fiber (extrafibrillar crystallites). SAD patterns suggested that these electron dense substances were hydroxyapatite crystals. Furthermore, from the SAD pattern and dark field electron image of intrafibrillar crystallites, it was presumed that the crystallographic c-axis of apatite crystals oriented to the direction of collagen fibril.

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Preterm birth is a major global health issue, and its causes and underlying mechanism remain obscure. We recently established a mouse model of spontaneous preterm birth. In this model, endometrial cellular senescence early in pregnancy via mTORC1-p21 signaling is a major contributor of preterm birth and fetal death, and these adverse phenotypes are restored by the inhibition of mTORC1 or p21. This role of endometrial cellular senescence in determining the timing of birth in mouse models may help us better understand the mechanism of the timing of birth in humans and develop new and improved strategies against preterm birth.

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