Hepatocytes adhesion

A recent study has shown that membranes made of a modified polyetheretherketone (PEEK-WC) are interesting materials for biomedical applications [23,24]. The cytocompatibility of PEEK-WC membranes was evaluated by culturing hepatocytes isolated from rat liver (Figure 43.6). The properties of PEEK-WC membranes were compared to polyurethane membranes prepared using the same technique, and commercial membranes (made of Nylon, polyethersulphone, and polyester). The results have shown that PEEK-WC membranes promoted hepatocyte adhesion most effectively and metabolic activities of cells cultured on these membranes improved significantly. 

Hepatocyte adhesion in GC-coated PS and PVLA-coated PS was found to be similar (94.7%) after 120 min incubation. Hepatocyte adhesion on the PVLA was facilitated by the galactose-specific interactions between asialoglycoprotein receptors (ASGR) of the hepatocytes and galactose residues of the PVLA... 

E.S. Carlisle, M.R. Mariappan, K.D. Nelson, B.E. Thornes, R.B. Timmons, A. Constantinescu, R.C. Eberhart, P.E. Bankey, Enhancing hepatocyte adhesion by pulsed plasma deposition and polyethylene glycol coupling. Tissue Eng. 6, 45-52 (2000)... 

Exposure of the SECs to pathogens or cytokines produced by other cells during stress induces activation of the SECs and subsequent production of cytokines, eicosanoids, and/or adhesion molecules. For instance, after activation with EPS, a main component of the walls of gramnegative bacteria and a major inducer of inflammation and non-specific immune functions [20], SECs produce a number of pro- and anti-inflammatory cytokines. Pro-inflammatory cytokines shown to be produced were tumour necrosis factor alpha (TNFa) [26] interleukin-1 alpha/beta(IL-lo/p) [27] the major inducer of acute phase proteins interleukin-6 (IL-6) [28] and the neutrophil chemo-attractant interleukin-8 (IL-8) [29]. Anti-inflammatory cytokines shown to be produced were interleukin-10 (IL-10) [27] and hepatocyte growth factor (HGF) [30]. 

The hepatocytes was subcultured for 2 days and their albumin secretion activity was measured. The TRS-harvested hepatocytes showed nearly the same albumin secretion activity as the primary culture, whereas the ERS-harvested ones showed only 20% activity. This finding is important because no subculture of hepatocyte has ever been successful, owing to a possible proteolytic disruption of cell-membrane structure (especially cell-cell adhesion) in the course of trypsin treatment. 

There is emerging evidence that OSA may be a pro-inflammatory disorder with elevated circulating cytokines [60]. Abdominal visceral fat is a major reservoir of cytokines, and obesity is a leading risk factor for the presence of OSA [60], The mechanism(s) whereby pro-inflammatory cytokines are elevated in OSA is not fully elucidated, but may be related to the excessive sympathetic nervous system activation notable in OSA. Tumor necrosis factor (TNF)-a and interleukin (IL)-6 levels are elevated in OSA [61,62] and the circadian rhythm of TNF-a is disrupted in OSA [63]. IL-6 levels are higher again in OSA patients with systemic hypertension compared to normotensive apneics [60], IL-6 levels return to normal in OSA patients treated effectively with CPAP [64]. Other mediators of inflammation elevated in OSA include intercellular adhesion molecule-1 and C-reactive protein, the latter being synthesized primarily in hepatocytes in response to IL-6 [60], The presence of these and other pro-inflammatory cytokines may link to the increased prevalence of cardiovascular morbidity in OSA. 

Another method to retain cells is to trap the cells inside a polymer matrix. For instance, mammalian cells were entrapped in PEG-based hydrogel fabricated in glass-Si chips (see Figure 8.19). The cells included murine 3T3 fibroblasts and SV-40- transformed murine cells (i.e., hepatocytes, macrophages). A cell adhesion... 

Johansson S, Hook M. Substrate adhesion of rat hepatocytes on the mechanism of attachment of fibronectin. J Cell Biol 1984 98 810-817. 

Adhesion to organ-specific structures can also be used to select metastatic variants, that will usually show increased homing to the tissue used for selection. In this way, B16 melanoma cells have been selected on lung cryostat sections (Netland and Zetter, 1981), Lewis lung carcinoma cells on hepatocyte monolayers (Brodt, 1989), and RAW117 large-cell lymphoma cells on hepatic sinusoidal cells (LaBiche et al., 1993). 

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