Induction of inner ear hair cell-like cells from Math1-transfected mouse ES cells.

Math1, a basic helix-loop-helix transcription factor homolog of the Drosophila atonal gene, is considered to be a key factor for induction of sensory hair cells (HCs) during development of the organ of Corti or cochlea. Although embryonic stem (ES) cells are able to produce HC-like cells, the role of Math1 in induction of those cells has not been thoroughly elucidated. In the present study, we introduced Math1 into ES cells in order to achieve efficient generation of HC-like cells. ES cells carrying Tet-inducible Math1, Math1-ES cells, were generated using a Tet-On gene expression system. Embryoid bodies (EBs) formed in the absence of doxycycline (Dox) for 4 days were allowed to grow for an additional 14 days in the dishes in the presence of 400 µg/ml of Dox. At the end of those 14-day cultures, approximately 10% of the cells in EB outgrowths expressed the HC-related markers myosin6, myosin7a, calretinin, α9AchR, and Brn3c (also known as Pou4f3) and showed formation of stereocilia-like structures, whereas few cells in EB outgrowths grown without Dox showed those markers. Reporter assays of Math1-ES cells using a Brn3c-promoter plasmid demonstrated positive regulation of Brn3c by Math1. Furthermore, such HC-related marker-positive cells derived from Math1-ES cells were found to be incorporated in the developing inner ear after transplantation into chick embryos. Math1-ES cells are considered to be an efficient source of ES-derived HC-like cells, and Math1 may be an important factor for induction of HC-like cells from differentiating ES cells.

In vitro differentiation of mouse embryonic stem cells into inner ear hair cell-like cells using stromal cell conditioned medium.

Hearing loss is mainly caused by loss of sensory hair cells (HCs) in the organ of Corti or cochlea. Although embryonic stem (ES) cells are a promising source for cell therapy, little is known about the efficient generation of HC-like cells from ES cells. In the present study, we developed a single-medium culture method for growing embryoid bodies (EBs), in which conditioned medium (CM) from cultures of ST2 stromal cells (ST2-CM) was used for 14-day cultures of 4-day EBs. At the end of the 14-day cultures, up to 20% of the cells in EB outgrowths expressed HC-related markers, including Math1 (also known as Atoh1), myosin6, myosin7a, calretinin, α9AchR and Brn3c (also known as Pou4f3), and also showed formation of stereocilia-like structures. Further, we found that these cells were incorporated into the developing inner ear after transplantation into chick embryos. The present inner ear HC induction method using ST2-CM (HIST2 method) is quite simple and highly efficient to obtain ES-derived HC-like cells with a relatively short cultivation time.

Suppression of apoptosis in hepatocytes by fructose-modified dendrimers.

By immobilizing fructose-modified dendrimers on a polystyrene culture plate, the number of initially adhered hepatocytes on it was increased. Moreover, increasing the number of generations of fructose-modified dendrimer (fructose-dendrimer) increased the number. Urea synthesis per unit area also was increased, corresponding to the increase in the number of initially adhered hepatocytes. This result suggests that the fructose-dendrimers do not cause a decline in cell function. On the other hand, apoptosis of hepatocytes occurs during cultivation, and results in a decrease in the number of adhered cells and a decline in cell function. Fructose-dendrimers were found to suppress apoptosis of hepatocytes. This characteristic is considered to be responsible for the increase in the number of initially adhered hepatocytes without a decline in cell function. Fructose-dendrimers are shown to be very suitable scaffolds for use in a high-performance bioartificial liver support system.

Revascularization of the occluded donor artery of a femorofemoral crossover by axillary bypass.

In patients over 70 years of age with disabling leg ischaemia, femorofemoral crossover bypass with an externally supported polytetrafluoroethylene (PTFE) graft is the treatment of choice for unilateral occlusion of the iliac artery. Over a 6-year period, 18 elderly patients underwent femorofemoral bypass, six of whom had received percutaneous transluminal angioplasty before surgery for stenosis of the contralateral external iliac artery (donor artery). Symptoms of ischaemia recurred in three patients because of deterioration of the donor iliac artery more than 2 years after surgery, although all three grafts were well visualized by angiography. Revascularization was attempted in these three patients by an axillary bypass. Disabling symptoms of ischaemia were completely relieved by this procedure, although two patients underwent reoperation 9 and 16 months after the axillary bypass respectively. All three patients are now free from symptoms of ischaemia. It is concluded that: deterioration of the donor iliac artery after femorofemoral bypass does occur, although it has been considered unlikely because of decreased peripheral resistance; in spite of complete occlusion of the donor artery, grafts remain patent, proving the excellent antithrombogenic activity of externally supported PTFE; and revascularization using additional axillary bypass is a feasible procedure in such cases.