Desenvolvimento de técnica de cultivo para produção de células tumorais em forma de agregados em biorreator de vórtices de Taylor
Abstract
Cultivation of animal cell is gaining great interest in various biotechnological
applications. The growth of cancer cells in particular has been used for cancer -fighting drugs
tests. The major obstacle faced in the present is that of the drugs that have a good effectiveness
in cultured cells, few have the same result in clinical trials. Antitumor drugs are tested in cells
that are grown in two dimensions (2D), whereas tumor cells in organisms grow in three
dimensions (3D). For this reason, there is a need to establish a methodology for cultivation of
cells in 3D, like in spheroids model, because in these cells mimic the tumors in vivo. Several
methodologies for production of spheroids are being searched, and the dynamic model, which
is usually held in bioreactors, presents the advantage of producing a large amount of spheroids.
A big drawback of using bioreactors is the agitation required to maintain homogeneous
environment can be lethal to cells. To work around this problem, different types of bioreactors
have been researched, and the Taylor vortices bioreactor, characterized by low shear stresses
generate. As a supporting feature to reduce cell death to improve cellular aggregation, the
viscosity of the culture can be increase by the use of inert additives such as dextran. The aim of
this work is to identify important factors to reduce the lethal effects of agitation and facilitate
the formation of spheroids using a bioreactor of Taylor and increase the viscosity of the medium
with dextran use. Using a bioreactor of Taylor of 100 mL were made eight experiments of tumor
RT4 lineage of bladder cancer using two methods of agitation. For each agitation methodology,
four cultures were used at two stirring levels and two viscosity levels in McCoy’s medium at
37 ºc and pH around 7.20. In all these cultures, it was possible to obtain spheroids, however the
culture of 90 rpm, 0,80 cp and intermittent agitation was the only in which was obtained
spheroids with a mean diameter in the range of 300 to 400 μm were obtained, there were few
spheroids produced. In most cultures spheroids were obtained in the range of 100 to 200 μm
and with circularity values close to 0.80. In general, crops with higher viscosity provided better
aggregation results. It was possible to use the aggregation model of Smoluchowski to show the
aggregation formation kinetic from RT4 cells in the BVT .