FibraCel^® Disks
A Solid Support Growth Material for Mammalian, Animal & Insect Cells

Setting new standards for system design, delivery and affordability.

FibraCel disks are a proven support system used to increase yields of suspension and anchorage-dependent cultures. They can be used in NBS' CelliGen Plus, CelliGen 310 and BioFlo 4500 bioreactors, and are at the heart of our Spinner Basket and new FibraStage Disposable Cell Culture Sytems. FibraCel is also available for use in disposable bags, shake flasks and other bioreactor systems.

Animal cells such as hybridoma, insect and various anchorage-dependent recombinant cells have all been successfully grown using FibraCel disks. FibraCel disks are manufactured according to cGMP guidelines and is composed of polyester non-woven fiber and polypropylene (Figure 1). FibraCel disks are also treated electrostatically to facilitate suspension cells adhering to the disks and becoming trapped in the fiber system, where they remain throughout the process. The disks are predominately used as a matrix for the growth of cells when secreted products are desired.

A number of cell lines often have difficulty attaching to the surface of microcarriers. Cell lines such as MRC5 often require ideal conditions of temperature in order to attach to the support, frequently resulting in reduced cell viability. MRC5 as well as most other cell lines (Table 1) attach more readily to flat surfaces of the FibraCel disk because they become embedded in the fiber system (Figure 2).

Table 1 - Summary of cells
successfully used on FibraCel disks

Hybridoma	Anchorage-Dependent	Insect
DA4.4 123A 127A GAMMA 67-9-B	3T3, COS, Human Osteosarcoma MRC-5, BHK, VERO CHO, rCHO-tPA rCHO - Hep B Surface Antigen HEK 293, rHEK 293 rC127 - Hep B Surface Antigen Normal Human Fibroblasts Stroma Hepatocytes	Tn-368 SF9 rSF9 Hi-5

Cell density and productivity achieved with cells grown on FibraCel disks can be up to ten times higher than anchorage-dependent cells growing on microcarriers (or yields of suspension cultures).

Advantages of FibraCel over standard microcarrier systems
The advantages and benefits of FibraCel disks over standard microcarrier technology:

• Low pressure drop across the bed.
  • Scale-up of cell culture systems generally requires equalization of pressures over the microcarrier bed and a examination of the pressure variation effect on viability throughout the microcarrier bed. However, the low pressure drop of FibraCel minimizes this variability and maintains a global viability of cells over the entire bed.
    
    
• High surface-to-volume ratios.
  • The increased ratio increases the total biomass that can be maintained in the bioreactor. This coupled with the greatly enhanced production of cellular products dramatically increases the efficacy of FibraCel over standard microcarrier culture.
    
    
• Less susceptibility to shear forces from impeller blades and sparger gas bubbles.
  • It is commonly seen in standard microcarrier culture that the beads are fractured (with concurrent destruction of culture) due to normal use of impeller blades and gas inclusion. FibraCel disks maintain their integrity (and production levels) and cells entrapped are shielded from the turbulence of impeller rotation and sparged gases.
    
    
• Higher mass transfer of nutrients and oxygen.
  • Analysis of the cells located at the bottom of the bed indicate that they are as viable as the cells located at the top due to the uniform mass transfer of nutrients and oxygen in the FibraCel basket system.
    
    
• Easy and efficient separation of biomass from secreted products.
  • FibraCel offers sustained long-term periods of high-density growth in perfusion, without any danger of clogging and with elimination of the need for cell filtration to separate cells from product.

Normally it takes approximately 6 hours for cells to attach to microcarriers (with a normal inoculum of 1 x 106 cells/mL), whereas cells can attach within 15 – 60 minutes on FibraCel disks. Moreover, the growth process for microcarrier cultures can require extended delays for periodic stoppage of stirring to allow time for cells to become attached. By comparison, the FibraCel bed is inoculated (3 x 105 cells/mL) in a single step.