In vitro transanastomotic endothelialization was studied using a mathematical model with the Fisher equation. The Fisher equation is a nonlinear parabolic equation which has a cell migration term and a population growth term. The mathematical model was used to simulate recent experiments performed to investigate quantitatively the unidirectional formation of a bovine endothelial cell monolayer in vitro. The two parameters included in the equation were estimated using a trial and error method in which the calculated solutions of the various values of the two parameters are compared with the experimental data and the best fit pair is adopted: one parameter, D, which represents the unidirectional cell migration rate and the other, k, which represents the population growth rate. The calculated solutions fit the experimental data well. We also simulated the healing of a mechanically disrupted endothelial monolayer sheet. The significance of cellular biomechanics in tissue formation and design of tissue-engineered devices is discussed.

We developed a reliable and quantitative method for measuring the dynamic process of unidirectional two-dimensional (2-D) tissue formation of endothelial cells (ECs) in vitro. The culturing of bovine ECs in an assembled culture chamber provided a square monolayered cell sheet with a linear margin when disassembled at the confluency. The cell sheet maintained in culture showed a unidirectional which was determined from the daily observation of tissue, allowed us to determine quantitatively the dynamic process of unidirectional endothelialization in vitro. The endothelialized distance and the endothelializing zone on a glass slide were found to be nearly 500 microns/day and 750 microns in width, respectively. Thus, the method developed here provided information of the 2-D tissue formation process. This model would be useful as an in vitro model which simulates the anastomotic endothelialization of an artificial vascular graft.

We investigated the effects of cellular senescence on unidirectional endothelialization in vitro, simulating the anastomotic endothelialization of vascular prosthesis. The experiments were carried out with three different cumulative population-doubling levels (CPDLs) of bovine aortic endothelial cells (ECs), which have finite life span. Young ECs with 22 CPDL, middle aged with 46, and senescent with 70 at the time of inoculation were used. The effect of aging on unidirectional endothelialization, as well as cellular morphology and proliferative and migratory potentials of isolated cells, were qualitatively and quantitatively analyzed. The unidirectional endothelialization rate was determined by our newly designed method to prepare the square monolayer sheet with linear margins between cell-adhesion and noncell-adhesion regions. The results showed that endothelial cell senescence retarded not only proliferation and migration but also unidirectional endothelialization. Time-lapsed videomicroscopic study of unidirectional endothelialization process revealed that ECs at several rows back from the leading edge represented much slower rate of migration than did the ECs at the leading edge. These findings suggest that high cellular mobility observed for the ECs at the leading edge may result in localized excessive cell replication. Thus, atherosclerotic vessels containing senescent or injured ECs may have limited capability of anastomotic endothelialization.

Atresia in the aortic arch is a rare and severe congenital cardiovascular anomaly. Without surgical therapy, only a few patients can survive to adulthood. A 29-year-old woman with atresia of the aortic arch (Celoria-Patton Type A) without any intracardiac shunt underwent primary surgical correction involving reconstruction of the aortic arch with prosthetic interposition between the transverse aortic arch and the descending aorta and division of the persistent ductus arteriosus. Her postoperative course was uneventful, and she is now doing well at three years to date after surgical treatment.

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