Biomedical Engineering Reference
In-Depth Information
organisms in developmental biology and the variety of genetic mutants that
have been created further underscore the value in expanding the use of
these models in the investigation of cell motility.
Aortic ring assay
This assay is an
ex vivo
organ culture approach that attempts to bridge the
gap between
in vitro
and
in vivo
. The aortic ring is explanted and embedded
in a collagen or fi brin gel to achieve an environment that permits three-
dimensional (3D) growth and migration of cells out from the aorta (Nicosia
and Ottinetti, 1990). Image analysis permits the counting of cells migrating
and growing out from the native 3D environment that includes cell-derived
matrix and multiple cell types. This assay has been used extensively for 30
years, primarily for the investigation of angiogenesis (Nicosia, 2009).
Extracellular matrix plug assay
This assay is based on the injection of a collagen or Matrigel plug into mice.
Matrigel is a reconstituted basement membrane matrix that is derived from
the extract of Engelbreth-Holm-Swarm tumors in mice (Kleinman and
Martin, 2005). This material is frequently used to study invasion and angio-
genesis because it resembles the complex extracellular environment found
in many tissues and it supports cellular behaviors that are not observed on
standard culture materials. In one confi guration, the cells are suspended in
the Matrigel prior to injection into mice (Skovseth
et al.
, 2005). In other
applications, the cell-free plug is injected and cell invasion into the Matrigel
is quantifi ed (Kibbey
et al.
, 1994). The biggest limitation of this assay is that
it is inherently an endpoint assay and is typically scored by histological
staining.
3.6 Conclusion and future trends
Based on the importance of cell adhesion and migration in biomaterials
applications, it is clear that bioengineers will continue to develop technolo-
gies that overcome the limitations of current systems and enable more
sensitive measurements of these critical processes. In parallel, the rapidly
expanding assortment of available genetic manipulation tools will facili-
tate the ability of these and emerging quantitative assays to elucidate the
mechanisms that regulate cell adhesion and motility. While not comprehen-
sive, this review describes the most commonly used assays to quantify cell
adhesion and motility on biomaterials. In addition, several developing tech-
nologies and recent approaches deserve mention as promising methods to
characterize cell adhesion and locomotion.
