Here, we'd like to summarize the brief history of regenerative medicine, finally focusing on cell sheet engineering developed by us. Conventionally, two methods for cell delivery to host tissues have been utilized: one is single cell suspension injection, and the other is the utilization of biodegradable scaffolds, although both have the intrinsic shortcomings. In order to overcome the shortcomings, we initiated the development of a new type of tissue engineering ten years ago. Using temperature-responsive culture surfaces, cultured cells can be harvested as intact sheets by simple temperature changes, thereby avoiding the use of proteolytic enzymes. Cell sheet engineering therefore allows for tissue regeneration by either direct transplantation of cell sheets to host tissues or the creation of thick constructs via the layering of individual cell sheets. In this review, we compare these three with referring to adverse inflammatory effects.

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Thymic epithelial cells (TEC) play pivotal roles in the establishment of self-tolerance through critical dialogue with developing thymocytes. Unique actions of NF-κB activation pathway within TECs for the establishment of self-tolerance have recently been highlighted by studies using a strain of mouse bearing a natural mutation of the NF-κB-inducing kinase (NIK) gene (aly mice) and gene-targeted mice of IκB kinase α (IKKα). NIK-mutant strain manifests autoimmunity and disorganized thymic structure with abnormal expression of Rel proteins in the stroma. The autoimmune disease seen in NIK-mutant mice was reproduced in athymic nude mice by grafting embryonic thymus from NIK-mutant mice. Similarly, an autoimmune-disease phenotype was induced in nude mice by grafting embryonic thymus from IKKα-deficient mice. The thymic microenvironment that caused autoimmunity in NIK- and IKKα-dependent manner was associated with defective processing of NF-κB2, resulting in the impaired development of thymic epithelial cells. Thus, a novel function for NIK-IKKα pathway in thymic organogenesis for the establishment of central tolerance has emerged.

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Regenerative medicine has currently emerged as one of the most promising therapies for patients suffering from severe heart failure. Direct implantation of isolated skeletal myoblasts and bone-marrow derived cells has already been clinically performed and research on fabricating three-dimensional (3-D) cardiac grafts using tissue engineering technologies has also now been initiated. In contrast to scaffold-based methods, we have proposed cell sheet-based tissue engineering, which involves stacking confluently cultured cell sheets to construct 3-D cell-dense tissues. Upon layering, individual cardiomyocyte sheets integrate to form a single, continuous, cell-dense tissue that resembles native cardiac muscle. When transplanted directly to host hearts, these engineered myocardial tissues are able to form morphological connections to the host with the presence of functional gap junctions. The transplantation of layered cardiomyocyte sheets has also been shown to be able to repair damaged cardiac muscle. As a next step, we have attempted to promote neovascularization within bioengineered myocardial tissues to overcome the longstanding limitations on engineered tissue thickness. Finally as a possible advanced therapy, we are now trying to fabricate functional myocardial tubes which may have the potential for circulatory support. Cell sheet engineering technologies therefore shows enormous promise as a novel approach in the field of myocardial tissue engineering.

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One of the fundamental features associated with inflammatory respiratory disease is the change in sugar chains' contents on airway mucins. This change has been related to an unfavorable change in mucin's visco-plasticity, and resulting in the impairment of mucociliary transport, vulnerability to viral/bacterial infection -- sugar chains playing a important role in adhesion of some viruses and bacteria to epithelium -- and inflammatory cell infiltration in the airway. Thus, we review and discuss recent studies on the topic, including our own data available, in terms of expression and role of sugar chains on mucins.
In brief, airway mucins from patients with inflammatory respiratory disease show increased levels of sialyl-Lewis x epitopes on mucin cores. The expression of the sialyl-Lewis x epitopes is regulated by a number of glycosyltransferases, and tumor necrosis factor-α is reported to up-regulate the expression of these glycosyltransferases. Recently, we found that inhibitors of phosphatidylinositol-phospholipase C (PI-PLC) can block this up-regulation of the glycosyltransferases. This suggests that a PI-PLC inhibitor might reverse the inflammatory damages in the airway where sialy-Lewis x epitopes have been overexpressed on mucin cores.
From viewpoints of drug treatment, we briefly refer to the estimated mechanism(s) of carbocisteine, a mucoregulant drug, in relation to the sugar-chain topic in this short review.

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Steroid-induced osteoporosis is the most common form of secondary osteoporosis. The mechanisms of glucocorticoid (GC)-induced osteoporosis may be divided into indirect and direct effects. A putative indirect mechanism of GC-induced osteoporosis is thought to be secondary hyperparathyroidism or estrogen deficiency. Recent studies, however, suggest that the direct action of GC on bone metabolism is more important. GC stimulates the expression of the receptor activator of NF-κB ligand (RANKL) and inhibits osteoprotegerin (OPG) expression in a dose-dependent manner in human osteoblasts. The resultant increase in the RANKL:OPG ratio results in the induction of osteoclastogenesis. GC predominantly inhibits human osteoblast proliferation and enhances the differentiation of human-pre-osteoblasts. GC also acts directly on human osteoblasts to up-regulate the expression of M-CSF which is an essential cytokine for the survival of osteoclast precursors. The addition of GC to the culture of human peripheral blood mononuclear cells (PBMC) results in a marked increase in the formation of osteoclasts and an increase in lacunar resorption. Moreover, GC has been shown to inhibit apoptosis in mouse osteoclasts. In addition, the direct effect of dexamethasone (Dex) upon human osteoclastogenesis from PBMC is mediated via the balance between RANKL and IFN-γ in activated CD4 T cells. Dex induced human osteoclastogenesis without adding osteoblasts or soluble RANKL. Dex dose-dependently increased the ratio of RANKL-positive cells to IFN-γ positive cells (RANKL:IFN-γ ratio) only by reducing IFN-γ-positive cells, suggesting that Dex stimulates osteoclast differentiation by elevating the RANKL:IFN-γ ratio in CD4⁺ T cells. The balance between RANKL and OPG (RANKL:OPG) or RANKL and IFN-γ (RANKL:IFN-γ) on osteoblasts and T cells may have an important role in GC-induced osteoclastogenesis. Thus, therapeutic modulation of the expression of RANKL, OPG and IFN-γ by osteoblasts and T cells represents a novel strategy to prevent GC-induced osteoporosis.

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BACKGROUND/AIM: To determine the sustained viral response (SVR) rate and to investigate the baseline host and viral characteristics of chronic hepatitis C (CHC) patients who achieved an SVR with interferon (IFN) alone or IFN plus ribavirin.
PATIENTS AND METHODS: One hundred and forty-seven adults with CHC were studied. Baseline serum HCV-RNA was quantified by RT-PCR, and the HCV serotype was classified as S1 and S2. IFN therapy was selected according to the serum HCV-RNA load: IFN-alpha 2b plus ribavirin were given to 63 patients, while the other 84 patients were treated with IFN alone (53 patients received IFN-alpha or -alpha 2b, and 31 patients received consensus IFN). All IFNs were administered daily for 2 weeks, followed by the same dose thrice weekly for a median of 22 weeks (14-94 weeks). Twenty-four weeks after finishing therapy, SVR was defined as negative serum HCV-RNA by a qualitative PCR, and patients with any other outcome were defined as nonresponders. Peripheral blood CD4 positive T cell subsets (Th1 and Th2 cells), NK cells, serum cytokines, and standard liver function tests were measured before starting therapy.
RESULTS: An SVR was achieved in 87 patients, while 60 patients were nonresponders. Multiple logistic regression analysis revealed that the serum log 10-transformed HCV-RNA load, serotype, and liver fibrosis were independent factors for SVR. According to univariate logistic regression analysis, serum Log IL-10 and peripheral blood Th1 cells were significant predictors of SVR.
CONCLUSION: Our results suggest that an SVR is strongly associated with S2, serum HCV-RNA load, and mild fibrosis, even when therapy is chosen according the serum viral load and serotype.

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