CD8+ CD122+ regulatory T cells contain clonally expanded cells with identical CDR3 sequences of the T-cell receptor ß-chain.

We identified CD8(+)  CD122(+) regulatory T cells (CD8(+)  CD122(+) Treg cells) and reported their importance in maintaining immune homeostasis. The absence of CD8(+)  CD122(+) Treg cells has been shown to lead to severe systemic autoimmunity in several mouse models, including inflammatory bowel diseases and experimental autoimmune encephalomyelitis. The T-cell receptors (TCRs) expressed on CD8(+)  CD122(+) Treg cells recognize the target cells to be regulated. To aid in the identification of the target antigen(s) recognized by TCRs of CD8(+)  CD122(+) Treg cells, we compared the TCR diversity of CD8(+)  CD122(+) T cells with that of conventional, naive T cells in mice. We analysed the use of TCR-Vß in the interleukin 10-producing population of CD8(+)  CD122(+) T cells marked by high levels of CD49d expression, and found the significantly increased use of Vß13 in these cells. Immunoscope analysis of the complementarity-determining region 3 (CDR3) of the TCR ß-chain revealed remarkable skewing in a pair of Vß regions, suggesting the existence of clonally expanded cells in CD8(+)  CD122(+) T cells. Clonal expansion in Vß13(+) cells was confirmed by determining the DNA sequences of the CDR3s. The characteristic TCR found in this study is an important building block for further studies to identify the target antigen recognized by CD8(+)  CD122(+) Treg cells.

The use of high-hydrostatic pressure treatment to decellularize blood vessels.

A decellularization method using high-hydrostatic pressure (HHP) technology (>600MPa) is described. The HHP disrupts the cells inside the tissue. The cell debris can be eliminated with a simple washing process, producing clean, decellularized tissue. In this study, porcine aortic blood vessel was decellularized by HHP. The mechanical properties and in vivo performance of the decellularized tissue were evaluated. Mechanical properties of the decellularized tissue were not altered by the HHP treatment. Reduced inflammation of the decellularized tissue was confirmed by xenogenic transplant experimentation. An allogenic transplantation study showed that decellularized blood vessel endured the arterial blood pressure, and there was no clot formation on the luminal surface. In addition, cellular infiltration into the vessel wall was observed 4 weeks after implantation, suggesting that HHP treatments could be applied widely as a high-quality decellularization method.

Study on the physical properties of tissue-engineered blood vessels made by chemical cross-linking and polymer-tissue cross-linking.

In this study, we attempted to chemically cross-link decellularized blood vessel tissue and to perform cross-linking with a polymer in order to control its stability and functionalization. For this purpose, we cross-linked tissue by intrahelical, interhelical, and intermolecular cross-linking between the polymer and the collagen helix, which is a component of the native tissue. The intrahelically cross-linked tissue showed weaker stability against heat and degradation caused by collagenase compared to the interhelically cross-linked tissue. The tissue intermolecularly cross-linked with polymer showed the highest stability against heat and degradation caused by collagenase. The mechanical strength test showed that the Young's moduli were different for the intra/interhelically and intermolecularly cross-linked tissues, with the latter being stiffer. This is thought to be because the cross-linked polymer functions in the same way as elastin, whereas simple collagen cross-linking provides a supportive matrix that holds the collagen and elastin together.