Cytodex beads

Smith, M.A. W.W. Vale. 1981. Desensitization to gonadotropin-releasing hormone observed in superfused pituitary cells on cytodex beads. Endocrinology 108 752-9. 

Table 17.13 Growth of MRC5 Cells Cell Density versus Time for MRC5 Cells Grown on Cytodex I Microcarriers in 250 mL Spinner Flasks Inoculated at 2.26 and 4.76 cells/bead...

Beads may be supplied in suspension in PBS but more usually they are supplied dry and require swelling in PBS-A (100 ml/g) for 3 h and washing in PBS-A and autoclaving (15 min at 15 p.s.i.) before use. In the dry form they are stable for more than 2 years. One gram of Cytodex-1 (dryweight) will swell to about 18 ml containing 7 X 106 microcarriers with a surface area of 0.6 m2. 

Bio-Rad Laboratories supply Bio-Carriers . Instead of the cross-linked dextran of the Cytodex microcarriers these have a polyacrylamide matrix with the positively charged dimethylaminopropyl groups linked throughout the matrix. On swelling 1 g dry Bio-Car-riers provides 19 ml packed volume containing 7 X 106 beads with a total surface area of 0.5 m2. Each bead can accommodate 350 cells so that the theoretical value of 2 X 109 cells could grow on 1 g Bio-Carriers. 

Fig. 3.8. L929 cells were seeded in 100 ml GMEM with 10% calf serum at 3 cells per microcarrier bead onto 5 x10s Cl-(Cytodex 1), P(Biosilon) or G (Bioglas) beads. The cell number was estimated by releasing the cells with trypsin, briefly allowing the beads to settle and counting the cells with a Coulter counter. Difficulty was encountered releasing the cells from Cytodex, but cells attached only weakly to the glass and particularly to the plastic beads and many cells were free in suspension. The use of electronic cell counters is not recommended for counting cells released from microcarriers as the orifice occasionally becomes blocked by small microcarriers in the...

PHARMACIA (1978) Cytodex l — Beaded Microcarriers for Cell Culture (Pharmacia Fine Chemicals AB, Uppsala). 

Other examples for the successful employment of co-cultures are the interaction between muscle and nerve cells (Shahar et aL, 1985) and the co-cultivation of vascular endothelial and smooth-muscle cells using microcarrier techniques (Davies Kerr, 1982) co-cultivation of cerebellar granule cells, cerebral cortical neurons and cortical astrocytes on collagen-coated dextran beads (CytodexS) and the production and release of specific neurotransmitters and enzyme synthesis resembling in vivo interactions between neurons and astrocytes (Westergaard et aL, 1991). 

Add cell inoculum obtained by trypsinization of late log phase cells (pre-stationary phase) at over five cells per bead (optimum to ensure cells on all beads is seven) inoculate at the same density per square centimetre as with other culture types, e.g. 5-10 x 10 cm". Cytodex 3 at 2 g H inoculated at six cells per bead gives ... 

As stated earlier (Section 3.1.1)), it has always been a calorimetric problem to study the metabolism of cells adherent to a substratum. The obvious solution these days is to use beads in a bioreactor-type vessel. An early application of such a technique was the use of solid Cytodex 1 microcarriers (Pharmacia) to measure the heat production of anchorage-dependent green monkey kidney (Vero) cells [38] in a Thermometric stirred perfusion vessel [95]. As seen in Figure 39, the heat production was proportional to the number of cells assessed by counting in a Biirker chamber the number of nuclei released from cells and stained with a hypotonic solution of citrate containing crystal violet [38]. In recent years, different kinds of microcarriers have been manufactured that are optimised for specific cell types. 

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