Tissue engineering research: the engineer's role.

Tissue engineering holds the promise of revolutionary advances for health care. Academic, clinical and industrial efforts are increasingly directed towards the development of autogenic substitutes to restore, maintain, or improve tissue and organ functions. This article summarizes the role of the engineer in the multidisciplinary environment of tissue engineering research.

Effects of surface roughness on mechanical hemolysis.

Previous in vitro hemolysis test results showed that an inlet taper or a round corner in the leading edge of a stenotic connector played an important role in the reduction of hemolysis. However, computational fluid dynamics (CFD) analysis of these results indicated that the shear rate and hemolysis level were not always related to each other. Then, further research was performed, focusing on the effects of surface roughness on hemolysis. The results thus far can be summarized as threefold. First, the rate of hemolysis occurring at an abrupt change in the stenotic section was different if the longitudinal length of the stenosis was changed. The level of plasma-free hemoglobin after 6 h of circulation was decreased from 280 mg/dl to 70 mg/dl when the longitudinal length was shortened from 15 mm to 1 mm. Second, a comparison of hemolysis rates in identical stenotic connectors with differing surface roughness (Ra = 0.45 and 1.35 micrograms) revealed that a smooth surface achieved as much as an 80% reduction in the rate of hemolysis. Third, the in vitro hemolysis results obtained were further defined through CFD analysis.