Microcarrier particles

Microcarrier particles Can encapsulate antigen and be carried across the mucosal epithelium Biodegradable microspheres, liposomes, vims-hke particles, stimulating complexes (ISCOMM... 

According to Butler (1987), many materials have been used in the production of microcarrier particles, and they have specific requirements that allow appropriate cell adherence and growth ... 

Venkat, R. V., Stock, L. R., and Chalmers, J. J., Study of Hydrodynamics in Microcarrier Culture Spinner Vessels A Particle Tracking Velocimetry Approach, Biotechnol. Bioeng., 49 456 (1996)... 

Microcarriers are small particles, made of materials such as cellulose, dextran, glass, collagen, or gelatin. Generally, they have a spherical shape and present a surface structure and composition that promotes cell adhesion and growth. 

Many different culture systems have demonstrated effectiveness for viral production. As previously described, these systems are based on the growth of cells in suspension or adherent to microcarriers, which are kept in suspension by agitation. After achieving high density the cultured cells can be infected by virus, allowing intracellular viral multiplication until the viral products are finally collected and processed. After standardization and optimization, these systems allow consistent viral particle production, and these steps are called the synthesis or upstream phase. Figure 18.7 shows a typical cell membrane structure when rabies viral particles are leaving the surface of an infected cell. 

Microcarriers are small solid particles (kept in suspension by stirring) upon which cells may grow as a monolayer. They confer the advantage of large scale suspension cultures on anchorage dependent cells. They thus offer the following advantages. 

Microcarriers are very suited to virus production and in some cases virus particles are constantly shed into the medium. 

The population balance model of Mohler et al. [4], which forms the basis for the presented approach, describes the replication of influenza A viruses in MDCK cells growing on microcarriers. It is rmstmctured and includes three concentrated state variables, which are the number concentrations of uninfected cells Uc, infected cells /<, and free virus particles V. 

Venkat R.V. et al., Study of Hydrodynamics in Microcarrier Culture Spinner Vessel A Particle Tracking Velocimeter Approach, Biotechn. Bioengng, 49 (1996), p. 456-466... 

Adherent cells can be grown in stationary or microcarrier cultures [116]. Stationary cultures use devices such as flasks, roller bottles, and cell factories that provide wall surface area for cell attachment [117]. Microcarrier cultures, on the other hand, can be implemented in agitated bioreactors [114,116]. These microcarriers are small porous particles (0.2mm) that provide large surface areas for cell attachment and can be suspended in the culture medium by gentle agitation. The culture environment is thus easily controlled and the scale-up is done by increasing the... 

Three particle collision mechanisms can occur in an agitated vessel. These are (a) particle-vessel, (b) particle-impeller and (c) particle-particle. Most of the work on collisions has been related to secondary nucleation, but there are other systems where mechanical abrasion following impact may occur and may be undesirable, e.g. breakdown of friable catalysts, or in mammalian cell culture on microcarriers or desirable, e.g. removal of an impervious outer skin which forms on ore particles during some leaching processes. 

In this chapter, I would like to review polymer materials and bioencapsulation techniques focusing on the analysis of their merits and disadvantages, and to discuss some biomedical applications of nano- and microcarriers (both particles and capsules) with entrapped biomaterial, which have been recently reported in the literature. 

Cell death rate oc microcarrier size (particle abrasion is proportional to (d ) Nienow (2006))... 

The coUision/impact caused cell damage proposition of Cherry and Papoutsakis (1986) is also supported by Nienow (2006). It has been mentioned earlier that particle abrasion is proportional to This observation indicates that smaller size microcarrier beads should decrease the impact force. Cherry and Papoutsakis (1989a, b)... 

Microcarrier culture Microcarriers are small particles, usually spheres 100 to 300 fim in diameter that are suspended in stirred culture medium. The technique was initiated in 1967 but required considerable developmental work to produce a range of suitable microcarriers (e.g., the Cytodex series by Pharmacia). The first industrial process based on microcarriers was for FMDV. Subsequently, a wide range of microcarriers based on gelatin, collagen, polystyrene, glass, cellulose, polyacrylamide, and silica have been manufactured to meet all situations. The key criteria in the design of effective microcarriers were to make the surface chemically and electrostatically correct... 

Microcarrier culture has proven to be the most effective scale-up method for ADC, despite its limitations (critical procedures, low surface area-to-volume ratio of a sphere). To increase the surface area porous particles were developed. The initial particle was the Verax microsphere which was 500 fim in diameter and manufactured from bovine collagen. The interconnecting channels of 20- to 40- u.m diameter provided an internal open volume of 80% of the sphere. The spheres were fluidized at 75 cm/min upward flow, and cell densities in excess of 10 /mL intrasphere volume were achieved (equivalent to 4 x 10 /mL in the bioreactor). The sphere matrix provided a huge surface... 

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