BioAxFlow is designed for 3D cell culture in tissue engineering applications, particularly for bone tissue engineering.
With its advanced fluid dynamics and absence of mechanical components, it overcomes the major drawbacks of reactors currently used in tissue engineering, among which we find Rotating-wall vessels.
Rotating-wall vessels bioreactor, what it is and how it works
NASA developed the Rotating-wall vessels (RWV) as a simulator to mimic and model the effects of microgravity on cells in laboratory studies on Earth. Indeed, the goal of the device was to protect cell cultures from the high shear forces generated during the launch and landing phases of the Space Shuttle.
During the testing phases on Earth, it was discovered that the cells inside the bioreactor aggregated and formed spheroid structures similar to tissue. It was then guessed that the Rotating-wall vessels could be used to develop numerous three-dimensional cellular models.
The bioreactor consists of two concentric cylinders, a growth chamber crossed by an inner cylinder for gas exchange and oxygenation. The chamber is integrally filled with growth medium.
Once the motor is driven, a belt rotates the culture chamber along its horizontal axis; this way, the liquid inside accelerates until the fluid mass rotates at the same angular velocity as the wall. The result is a culture environment with minimal shear forces, in which the cells are uniformly suspended in the culture medium. Due to these conditions, the cells aggregate and initiate three-dimensional growth.
Both microcarriers and scaffolds can be used as supporting matrices within this bioreactor.
The latter turns out to be crucial for bone tissue engineering. However, from this point of view, Rotating-wall vessel bioreactors demonstrate some critical issues.
The main critical issues of a Rotating-wall vessels bioreactor for bone tissue engineering
The culture environment of the Rotating-wall vessels bioreactor has opened up new observations and experiments in tissue engineering. In particular, the bioreactor has been used to develop cartilage and bone tissue equivalents.
However, as reported in “Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor” (Sikavitsas, Bancroft et Mikos, 2001), the Rotating-wall vessels bioreactor has limitations.
The purpose of the study by Sikavitsas, Bancroft, et Mikos was to compare different types of 3D and 2D osteoblast-like cell cultures in terms of morphology, proliferation, and differentiation within Rotating-wall vessels, spinner flask, and static culture bioreactors.
During the experiments, it was noted that when multiple large scaffolds are placed in the Rotating-wall vessels, although free settling can be achieved, the collision of the scaffolds with the reactor walls cannot be avoided.
Such collisions momentarily disturb free settlement and can traumatize cells residing on the scaffold surface due to direct contact with the wall surface.
From this, it can be inferred that the rotating wall bioreactor damages the cells on the surface of the scaffold.
Not only that, at the end of the study’s observations, it was found that cell constructs cultured in the Rotating-wall vessels bioreactor had demonstrated slower proliferation, leading to inferior performance to other bioreactors examined in the study (spinner flask and static culture) about osteoblastic cell differentiation.
How BioAxFlow delivers a solution to these critical issues
Despite the excellent conditions inside the culture chamber, the very operation of the Rotating-wall vessels compromises the effectiveness of three-dimensional cell culture on large scaffolds.
The only solution would seem to be adopting a larger culture chamber. Or use another type of bioreactor that is more functional and versatile.
The critical issue raised by the size of the scaffold prompted the Cellex team to develop an innovative tissue engineering bioreactor that can address the need to use scaffolds of different sizes.
The BioAxFlow culture chamber is specifically designed to use any scaffold, not only in size but also in different geometries.
Individual component modules can be configured to meet the investigator’s needs, particularly regarding scaffold support and the scaffold itself.
BioAxFlow’s innovative fluid dynamics also allow cell seeding on the scaffold without trauma, solving another critical issue raised by Rotating-wall bioreactors.
Sources
“Formation of three-dimensional cell/polymer constructs for bone tissue engineering in a spinner flask and a rotating wall vessel bioreactor”, Vassilios I. Sikavitsas, Gregory N. Bancroft, Antonios G. Mikos, 2001
“Rotating-wall vessels, promising bioreactors for osteoblastic cell culture: comparison with other 3D conditions”, C. Granet N. Laroche L. Vico C. Alexandre M.H. Lafage-Proust, 1998