Assessment of perfusion bioreactors system using μCT technology and 3D modeling methods

To improve in vitro cell expansion and differentiation the use of bioreactor systems are being implemented e.g. in bone tissue engineering. Spinner flasks, rotating wall bioreactors, and flow perfusion systems have all been used, and each system has advantages and disadvantages [1]. This paper describes the development of a simple perfusion bioreactor system and the preliminary results from the assessment methodology employed which is based on μCT analysis and 3D Modeling Techniques. A simple bioreactor with flow generator propeller was designed and built with the aim of improving differentiation of human embryonic derived mesenchymal stem cells (hES-MP) seeded on porous titanium scaffolds with the aim to improve extracellular matrix formaton and mineralized matrix deposition. We designed a simple model to calculate the pressure generated by the flow of the bioreactor on the scaffold and compared 3 scaffolds under static culture conditions to 3 scaffolds within the bioreactor. The scaffolds were incubated for 21 days and then scanned with xray μCT. The images obtained were processed using a 3D imaging software, in this platform the scaffolds undergo a segmentation in order to obtain samples from the surface and from the scaffolds internal cavities. The data are further processed to calculate the gray value gradient distribution. The analysis of these distributions allows quantifying changes in scaffolds during static and bioreactor culture. The results show that scaffolds maintained in the bioreactor have higher density of gray values gradient distribution both on the scaffold surface and internal cavities which suggests improved mineralized matrix deposition.