OXYGEN IS A FACTOR DETERMINING IN-VITRO TISSUE ASSEMBLY - EFFECTS ON ATTACHMENT AND SPREADING OF HEPATOCYTES

Many recent studies related to the development of bioartificial liver devices have utilized hepatocytes cultured within devices of various g eometries. Because hepatocytes are anchorage-dependent cells, they nee d to attach and spread onto the extracellular matrix to be able to fun ction, a process that requires energy. Thus, it is important to delive r enough oxygen to hepatocytes contained within bioartificial liver de vices during the early phase of cellular organization while the cells interact with the extracellular matrix. In this study, we investigated the effect of oxygen on the attachment and spreading of hepatocytes. Increasing the gas phase oxygen from 0 to 160 mmHg resulted in an incr ease in the percentage of cells attaching from 43.0 +/- 5.8% to 103.6 +/- 29%, 1 h after seeding. In a similar manner, increasing the gas ph ase oxygen from 0 to 160 mmHn resulted in an Increase of the projected surface area from 310 +/- 35 to 827 +/- 127 mu m(2), 24 h after seedi ng. Furthermore, the partial pressure of oxygen at the cell level was estimated using a diffusion-reaction model. The model indicated that a cell surface oxygen partial pressure of 0.064 mmHg was required for t he half-maximal (K-m(a)) attachment of hepatocytes to collagen-based s ubstrate. On the other hand, the K-m(s) value of the spreading process was predicted to be 0.13 mmHg. The results of this study demonstrate the importance of oxygen during the initial stages of attachment and s preading of hepatocytes, and it has important implications in the desi gn of hepatocytebased bioartificial liver devices. (C) 1994 John wiley & Sons, Inc.