Tissue engineering, first conceived in the 1980s, is now drawing tremendous social attention as the research progresses. Scaffold materials used to engineer tissues have been traditionally synthetic polymers, biocompatible porous inorganic materials and purified extracts of natural extra-cellular matrices. To date, there are no biomaterials in clinical use that possess both the safety of the polymers and ECM-like 3-dimensional environment for cells. A group of self-assembling synthetic peptides ("PuraMatrixTM"), developed at MIT are composed solely of natural amino acids found in organisms. These peptides self-assemble into nano-fiber of approximately 10 nm in diameter under physiological conditions, resulting in formation of hydrogel. In this hydrogel, many cell types are shown to adhere and proliferate, and injection of the gel with or without cells, promotes regeneration of tissues such as bone, brain and cardiac tissue. This peptide hydrogel is shown to be safe by animal safety tests and may become available for clinical application soon.
We have developed a novel cultured skin model "Vitrolife-SkinTM" which is composed of two types of collagen sponges and two types of normal human skin cells, fibroblasts and keratinocytes. This cultured skin model has a two-layer system consisting of dermis and epidermis with cornified layers which likes a real skin. We have evaluated skin irritancy and skin corrosivity to alternate to animal testing and developed a novel chemical application procedure using this cultured skin model. Also, we have developed regeneration of full thickness skin defects using this cultured skin model with the aim clinical application. This report reviews our cultured skin model.
Many researches on tissue stem cells have been developed in the field of regenerative medicine. Some indicated that cultured dental pulp cells secreted dentin matrix. We transplanted subcultured human dental pulp cells, using alginate as a scaffold, into the subcutaneous layer of nude mice. By adding β-glycerophosphate into the culture media, we observed the expression of dentin sialophosphoprotein mRNA coding dentinsialoprotein (DSP). The increase of alkaline phosphatase, which is an indicative marker for odontoblast differentiation, was demonstrated. After 6 weeks of transplantation, formation of certain radiopaque structures was observed in situ subcutaneously. The immunohistochemical and fine structure study identified the expression of type I collagen, type III collagen and DSP in the calcifying tissue. Also, isolated odontoblast-like cells relating to dentin-like hard tissue formation and scattering autolyzing apoptotic cells were found. The study elucidates that subcultured dental pulp cells actively differentiate secretory cells and induce calcification in the alginate scaffold.