Biomedical Engineering Reference
In-Depth Information
Fig. 9
Migration of hematopoietic stem cells isolated from umbilical cord blood on var-
ious collagen samples. Concentration was 1.2 mg
/
ml for collagen and 0.4 mg
/
ml for
heparin and hyaluronic acid, respectively
Additional cell culture experiments were carried out on patterned 3D sub-
strates in order to combine the spatial constraints of a stem cell niche with
the influence of different extracellular matrix components of its microenvi-
ronment. Therefore, silicone molds of cavities with a size of 10 to 80
µ
mand
adepthof10
m were coated with reactive maleic anhydride copolymers and
subsequently reconstituted assemblies of collagen fibrils and cofibrils were
immobilized on top of it. Hematopoietic stem cells were seeded onto these
functionalized cell carriers. Depending on the size of the cavities cells dif-
ferentially adhered to these structures as exemplarily shown in the inset of
Fig. 10. In initial experiments adhesion and proliferation was followed over
a time period of 3 days. As shown in Fig. 10 the cells tend to preferentially
adhere to an intermediate size of cavities. This result points to a balanced
equilibrium of cell-cell contacts and cell-matrix contacts for the homing and
proliferation of hematopoietic stem cells, which is in agreement with the
observed small hematopoietic stem cell clusters found in vivo [113]. Fur-
ther experiments will follow up on these observations in order to unravel
the influence of different extracellular matrix compositions combined with
microcavities.
Theintroducedmethodforthepreparationandinsituattachmentoffib-
rillar collagen and glycosaminoglycans assemblies to reactive polymer coat-
ings comprises an efficient technique for a straightforward biofunctionaliza-
tion of cell culture carriers and medical devices. As a basic advantage the
µ
