Frequently Asked Questions

The Rotary Cell Culture System bioreactor consists of a rotating culture vessel with a co-axial oxygenator in the center. When the vessel is filled with culture media and rotated, the fluid with the vessel rotates as a solid body about the horizontal axis. The oxygenator rotates concurrently with outer wall of the vessel. These conditions produce laminar flow and minimal shear force inside the culture vessel. The cells are maintained in suspension by the resolution of the centrifugal, gravitational and Coriolis forces, so that cells placed in the RCCS bioreactor experience minimal mechanical stresses and are thus able to assemble into tissue-like aggregates. Gas transfer occurs by diffusion through the silicone oxygenator, thereby avoiding bubble formation and consequent turbulence.

For a more detailed explanation of how the Rotary Cell Culture System works and it's key features, view our Technology page.  Also, if you would like to view publications on this topic, we've listed several titles for the Fluid Mechanical Principles of the RCCS in our Bibliography.

Two dimensional cell culture has greatly contributed to our understanding of cell function and interaction; however, 2D culture provides limited information about cells' in vivo characteristics.  A key purpose of cell culture is to mimic the in vivo conditions within living organisms and consequently to facilite scientific investigation of tissues.  With the same purpose, 3D culture systems better model the 3D biology found in vivo.

Currently, the most common method for three dimensional cell culture is to seed cells into synthetic scaffolds within multi-well plates.  While this model has produced some promising results for 3D cell aggregates and tissues, it has the limitation of restricted mass transfer within the media and tissue contructs.   In contrast to cells' in vivo environment, which provides a steady flow of nutrients from surrounding networks of blood vessels, the static nature of the two dimensional cell culture plates hinders effective distribution of nutrients to the cells.

Dynamic culture systems such as spinner flasks and larger scale stirred tanks improve the mass transfer of nutrients.  However, the mechanical forces produced within these systems not only damage the cells, but prevent their aggregation.

Our Rotary Cell Culture System (RCCS) bioreactors provide excellent mass transfer and low mechanical stress conditions that encourage the formation of 3D cell cultures.  Several published studies using RCCS bioreactors demonstrate the efficacy of our bioreactor systems for 3D cell culture (see our Bibliography to view the list of these publications).  Furthermore, scaffolds can be incorporated with our systems to obtain the desired conditions of 3D scaffolds.

No, the cells and cell aggregates continuously fall through the media as the cell culture vessel rotates.  The cells' continuous motion in media the facilitates their exposure to nutrients.

The RCCS bioreactors must be housed in an incubator during operation.  The temperature within the bioreactor is controlled by the ambient temperature within the incubator.  Consequently, if 37° C is the desired tempearture for the contents of the bioreactor, the incubator's temperature must be set to 37° C.

As mentioned in the previous question, the bioreactor is housed in an incubator during operation. The gas in the incubator diffuses into the culture through the silicone membrane according to the gas concentration of the culture.  Therefore, as with the temperature, the gas concentration settings of the incubator determine the gas concentration within the culture vessel.  Additionally, larger vessel systems, such as the RCCS-1 and the RCCS-4H, incorporate air pumps that push gas from the incubator to increase gas exposure to the silicone membrane, and ultimately facilite gas exchange across the membrane.  Since the gas transfer occurs via diffusion across the membrane, it does introduce bubbles into the culture vessel.

The ideal rotational speed for RCCS culture vessels will vary for different studies.  In general, determining the ideal rotation speed depends on the diameter of the cell aggregate.  As the vessel rotates, the cell aggregates accelerate until they reach a sedimentation velocity, which is determined by the size the cell aggregate.  According to the Stokes equation, the sedimentation velocity is proportional to the square of the radius of the cell aggregate.  Therefore, as the aggregates grow in size, they sediment more rapidly.  It is thus necessary to increase the vessel's rotation speed to prevent the cell aggregates from colliding with the vessel wall.

The main purpose of the RCCS bioreactor is to minimize mechanical stress on the cells. The presence of even a few bubbles will increase turbulence, and thus mechanical stress.  In order to minimize bubbles,  the RCCS bioreactor should be operated with zero headspace- be sure to fill culture vessels with media as instructed in the user manuals.  Additionally, the gas transfer to the culture via diffusion through the silicone membrane also prevents bubble formation from air in the incubator. Small bubbles may appear over time due to cellular respiration, and these should be removed as necessary (a syringe can be used to remove bubbles effectively).  See the user manuals for detailed instructions on removing bubbles.

The original purpose of the RCCS bioreactor was to simulate microgravity. During ground experiments using this reactor, it was noticed that cells suspended in these reactors tended to form 3D aggregates. Since then, these RCCS bioreactors have been used in several fields of cell and tissue culture. Applications of the RCCS bioreactor range from basic cell biology to space biology, culturing stem cells for regenerative medicine and drug development and possibly, in the future, the development of therapies for disease and injury. For a detailed account of the various applications of the RCCS bioreactor, click here.

No; the Rotary Cell Culture Systems (RCCS) differ from roller bottle systems in both functionality and design.  Roller bottles are long plastic bottles with a large removable cap.  The contents of the roller bottle culture are usually transferred and sampled manually through the bottle's opening, and with some systems, automatically via interconnected tubing. Gas transport in roller bottle systems is also transferred directly via tubing.  Roller bottle systems are typically used for 2D culture systems where adherent cells attach to the walls of the roller bottle.  Roller bottles are arranged horizontally and rotated about their cylindrical axis.

The RCCS culture vessels comes in two models, the High Aspect Ratio Vessel (HARV), which is disc-shaped and the Slow Turning Lateral Vessel (STLV) which is shaped like a cylinder.  Both vessels have two syringe ports with valves, and one fill port; these openings allow easy and flexibility in sampling using a syringe or a pipet.  Gas transfer in the RCCS culture vessels occurs by diffusion across a silicone membrane.  The RCCS promotes 3D cell culture as cells remain suspended in the media as the vessel rotates.  Substrates such as microbeads or scaffolds can also be added to the vessels for anchorage-dependent cell types.

The beads and the cells can be loaded into the reactor at the same time, independent of each other. The conditions inside the reactor are such that the cells automatically attach to the beads after they are both loaded into the reactor.

Yes, an incubator is necessary in order to maintain the temperature, pH and oxygenation of the culture. Also, it should be noted that water evaporates through the silicone oxygenator into the incubator. This will lead to bubbles in the culture vessel. So, humidification is needed in the incubator in order to maintain the concentration of water vapor and prevent evaporation in the culture vessel.

This depends on the application for which you need our bioreactor. Another factor that obviously plays in is the budget. If cost is a major consideration, you might want to try the RCCS D. This system allows you to run a single experiment at a time. Usually, the 4D or the 4H systems are good to begin with because most often, you will need to run a few experiments at the same time and this system is a better long term investment. We also have reactors for specific applications, such as the stem cell culture systems. We can also custom-make reactors depending on the needs of the research study. The best way to get this question answered though, would be to call us on 800-853-0740. We have research scientists as well as technical sales personnel who could recommend reactors based on your specific applications.