Biomedical Engineering Reference
In-Depth Information
Orive et al. employed electrospraying to prepare alginate-agarose microcapsules encapsulated
with an antivascular endothelium (VE)-cadherin antibody secreting 1B5 hybridoma cells for the
inhibition of angiogenesis [104]. Tumor growth and lethality are dependent on angiogenesis, and
VE-cadherin is a key factor in the last step of angiogenesis. Therefore, there is much interest in using
antiangiogenesis agents to inhibit tumor expansion. By using the electrospraying technique, hybri-
doma cells can be encapsulated into biocompatible and semipermeable microparticles as a living
drug-delivery system that permits the exit of anti-VE-cadherin monoclonal antibodies but not the
entry of cellular immune mediators. In the process, the 1B5 hybridoma cells were suspended with
1.68% alginate-agarose (1:1) solutions (5
10
6
cells/mL). The cell-gel suspension was pumped
through a needle from a peristaltic pump and was electrosprayed into 55 mM anhydrous calcium
chloride-collecting solution as a gelling agent (pH 7.4) at a fl ow rate of 2.1 mL/h. The collecting
solution containing the microbeads was maintained in an ice bath for 20 min to provoke thermal
gelation of the agarose. The microcapsules-encapsulated 1B5 hybridoma cells were suspended in
0.05% poly-l-lysine (PLL) solution for 3 min and then were coated again with another layer of 0.1%
alginate for 3 min. Finally, the cell-encapsulated microcapsules were washed twice using saline
and transferred to a complete RPMI-1640 medium under normal culture conditions. Figures 11.48a
through 11.48d show the optical microscopic images of microcapsules encapsulated with 1B5 hybri-
doma cells on various days of postencapsulation (day 1, 9, 12, and 19). The results showed that the
microcapsules were spherical with an intact and defi ned membrane made of PLL and alginate. The
1B5 hybridoma cells grew gradually within the microcapsules and formed small aggregates, but
some beads presented large aggregates because of a high cell density. The 1B5 hybridoma cells
secreted anti-VE-cadherin antibodies during 9 days of culture, reaching a cumulative concentration
of 1.7 µg/mL. The results revealed that the antibody concentration inhibited microtubule formation
(reached 87%) in the
in vitro
angiogenesis Matrigel assay and the antiangiogenic effects depended
×
(a)
(b)
(c)
(d)
FIGURE 11.48
Images of growth profi le of 1B5 hybridoma cells encapsulated in alginate-agarose
microcapsules on various days (a) day 1, (b) day 9, (c) day 12, and (d) day 19. Average diameter of beads—
618
±
17 µm. (Reprinted from Orive, G. et al.,
Biotechnol. Bioeng.
, 76, 285, 2001. © John Wiley & Sons
Inc. With permission.)
