Surface Of Polyurethane Foam Research Articles

The formation of a spheroid of primary hepatocytes and the expression of liver-specific functions depend on the characteristics of polyurethane foam

Rapid formation of spherical multicellular aggregates (spheroids) of hepatocytes and expression of liver-specific functions are important in developing a hybrid artificial liver. The relation between these points and the surface characteristics of the culture substratum are investigated in this article. Polyurethane foam (PUF) was used as a culture substratum for hepatocytes. Rat, dog, and porcine primary hepatocytes spontaneously formed a spheroid within 1.5 days in the pores of a hydrophilic PUF with a contact angle of 53.4±2.7°. Rat and dog primary hepatocytes formed a spheroid within 3 and 7 days of culture, respectively, in hydrophobic PUF with a contact angle of about 100°. The rates of albumin secretion and ammonia metabolism at 5 days of culture of porcine hepatocytes were 31 μg of albumin/106 nuclei/day and 0.018 μmol of NH3/106 nuclei/h, respectively, about 2 times higher than the values with hydrophobic PUF. It is very important to control the hydrophilicity of the PUF surface to develop an effective artificial liver module.

Tissue plasminogen activator (t-PA) production by a high density culture of weakly adherent human embryonic kidney cells using a polyurethane-foam packed-bed culture system.

Weakly adherent cells of the 293 line attached well to the internal surface of polyurethane foam (PUF) and grew to the high density of 6.83 x 10(7) cells/cm3 PUF in stationary culture. The maximum productivity of tissue plasminogen activator (t-PA) was 0.158 IU/10(6) cells per day. The productivity decreased at the stationary phase of cell growth, so we designed a PUF-plate packed-bed culture system for high density culture and continuous production of t-PA. A maximal cell density of 3.24 x 10(7) cells/cm3 PUF and a t-PA productivity of 0.326 IU/10(6) cells per day were obtained in 25-day perfusion cultures. Although the cell density decreased to half that in PUF stationary culture, the t-PA productivity increased twofold and was maintained for 25 culture days.

High density culture of anchorage-dependent animal cells by polyurethane foam packed-bed culture systems

Monkey kidney cells (Vero) and Chinese hamster ovary cells (CHO-K1) attached to the internal surface of polyurethane foam (PUF) and grew to a high cell density (1.1 x 10(8) cells/cm3 PUF and 4.2 x 10(7) cells/cm3 PUF, respectively) in a PUF-plates packed-bed culture system. This density of Vero cells was twice that obtained previously with a PUF-particles packed-bed culture system. A maximum cell density of 6.7 x 10(7) cells/cm3 culture vessel volume was obtained in a PUF-disc packed-bed culture of Vero cells. From the cell density of CHO-K1, growing in a monolayer on the surface of PUF and a petri dish, per bulk volume of PUF, we estimated that a surface area to volume ratio of PUF plates effective for cell growth was about 109 cm2/cm3.

Anchorage-dependent mammalian cell culture using polyurethane foam as a new substratum for cell attachment.

Anchorage-dependent mammalian cells were cultivated at high cell density in a novel culture system using polyurethane foam (PUF) as a substratum for cell attachment. PUF has a macroporous structure giving a high surface area to volume ratio. Monkey kidney cells (Vero) and Chinese hamster ovary cells (CHO-K1) attached to the internal surface of PUF and grew to a high cell density (1.04 X 10(8) cells/cm3 PUF and 3.5 X 10(7) cells/cm3 PUF, respectively) in PUF stationary cultures. In addition, we have designed a PUF-particle packed-bed culture system for high density mass cell culture. A maximum cell density of 2.4 X 10(7) cells/cm3 culture vessel volume was obtained in a packed-bed culture of Vero cells.

ELECTRON AND LIGHT MICROSCOPY EXAMINATION OF CAPSULES AROUND BREAST IMPLANTS

An investigation, by scanning electron microscopy of the capsules formed around silicone breast implants revealed that they consist almost entirely of connective tissue. In contrast, the capsules around the Y-prostheses (with a polyurethane foam surface) showed a foreign body reaction. We believe that excessive capsule formation around silicone implants is, among other factors, most likely due to discrete or moderate bleeding with subsequent hematoma formation. Therefore, we favor a two-stage procedure for subcutaneous mastectomy with insertion of the implant at 4 to 6 months after the excision.