Perfusion culture of hepatocytes within galactose‐derivatized biodegradable poly(lactide‐co‐glycolide) scaffolds prepared by gas foaming of effervescent salts

Abstract

Galactose, a specific ligand for asialoglycoprotein receptor in hepatocytes, was immobilized onto the internal surface of highly porous biodegradable poly(D,L-lactic-co-glycolic acid) scaffolds prepared by gas foaming of effervescent salts. Rat hepatocytes seeded within the scaffolds were cultivated by using a continuous flow and perfusion reactor system. Flow rate of medium circulating through the closed loop bioreactor system was optimized to minimize the extent of cell washout from the scaffold/cell construct while satisfying the oxygen transport rate to the seeded hepatocytes. Using the flow culture system, the scaffolds immobilized with galactose onto its internal surface retained a greater number of hepatocytes than those with unmodified or immobilized with glucose due to specific interactions between seeded hepatocytes and galactose moieties exposed onto the surface of the scaffolds. The perfusion culture system based on galactose-modified macroporous scaffolds, under optimal flow conditions, resulted in much higher albumin secretion rate, approximately 70 pg/cell/day for 7 days, compared to that with glucose modified scaffolds used as a negative control. The enhanced functional activity of hepatocytes seeded within the galactose modified scaffolds was likely caused by the formation of aggregated hepatocytes within the scaffolds.

Real time in vitro measurement of oxygen uptake rates for HEPG2 liver cells encapsulated in alginate matrices

“…To enable a direct comparison between the growth of cells on the substrate and within the gel, we have chosen to keep the initial density of 100,000 cells/ml for all samples in the experiments. The calculated values of OURs for the Hep-G2 cells is in agreement with the OUR of rat hepatocytes obtained from published literature (Balis et al 1999;Guarino et al 2003;Chandel et al 1997;De Bartolo et al 1999;Park 2002;Schumacker et al 1993;Smith et al 1996). The values seen in the literature also tend to vary greatly depending on the method of cell culture, time period of cell culture and method of measuring OUR.…”

“…Their results indicate that the OUR spans a broad range from 0.0167 to 1 nmol/s/ 10 6 cells (1-60 fmol/min/cell) (Balis et al 1999;Chandel et al 1997;De Bartolo et al 1999;Park 2002). Rotem et al developed a perfused system employed with mini-Clarktype oxygen electrode and measured the bulk oxygen concentrations at the inlet and outlet streams to predict the OUR of rat hepatocytes cultured on and sandwiched between collagen gels (Rotem et al 1992(Rotem et al , 1993Foy et al 1994).…”

“…For measuring key analytes in tissue microenvironment, sol-gel films containing the dye is employed to clad the core of an optical fiber (Campbell and Uttamchandani 2004;Khijwania and Gupta 1999;O'Keeffe et al 1995;Tang et al 2003), as a patch attached to the bottom of glass spinner (Guarino et al 2003;Lung et al 2004) and as a tip of an optical probe (Khohls and Scherer 2000). The compact size and ability of fiber optic sensors to directly measure dissolved oxygen in the culture medium without the additional use of reagents make them ideal for monitoring tissue growth in real time (Park 2002;Rotem et al 1992Rotem et al , 1993. Their ability to withstand sterilization techniques reduces the possibility of contamination.…”

Subsieve-size agarose capsules enclosing ifosfamide-activating cells: a strategy toward chemotherapeutic targeting to tumors

“…It is interpreted as a result of an alteration of the enclosed cells in adapting to the new microenvironment. Such a change in secretion productivity of individual cells according to the surrounding microenvironment has been observed for both unenclosed cells (18) and enclosed cells in agarose microcapsules (19).…”

Theranostic pH-sensitive nanoparticles for highly efficient targeted delivery of doxorubicin for breast tumor treatment

“…Many previous studies have reported that drug delivery vehicles with pH-sensitive chemical bonds accelerate drug delivery and cause release at a lower pH. 16,17 Iron oxide nanoparticles (IONPs), a promising magnetic resonance imaging (MRI) agent, are extensively used in the field of cancer theranostics; they facilitate the description of targeted therapeutic drugs and the diagnosis of the lesion areas. 18,19 Researchers have verified that external magnetic induction allows DOX-containing nanoparticles to preferentially concentrate at the tumor site, and thereby increase the drug levels for an enhanced therapeutic effect.…”