Interfaces in Composite Materials - Biointerfaces: Where Material Meets Biology - page 167

joining

Cartilage side Chondrogenic cells

Culture media

d n 3 r 4 n g | 1

Co-culture Osteochondral

construct

Bone side Osteogenic cells

Culture media

(I)

Cartilage side

Chondrogenic cells

Bone side
(II)

Osteochondral
construct

Co-culture

Osteogenic cells

Cartilage side

Bone side
(III)

Stem cells

Osteochondral
construct

Co-culture

Figure 7.3 Diagrammatic representation of various strategies of bilayered con-
structs used for osteochondral regeneration. The scaffold consists of
an upper chondral phase, required to reproduce the lubricating and
shock-absorbing function of articular cartilage and the lower osseous
phase required to provide the mechanical support for the subchondral
bone. These two phases were then joined by suturing or using a material
that simulates the extracellular matrix (I) scaffolds where each phase was
separately cultured with the specific cells; the differentiated phases were
then joined and co-cultured to form the osteochondral construct, (II)
single but heterogeneous scaffolds, where each portion is seeded with
the proper cell population (III) single and homogenous scaffolds where
the whole scaffold was seeded with stem cells that would be differen-
tiated into both chondrogenic and osteogenic lineage according to the
inducing conditions.
Modified from Nooeaid et al. 222

.

have short half-lives in vivo. 154,155 To overcome this problem, platelet-rich
plasma functionalized scaffolds or gene-activated scaffolds have been
utilized. 157,158
Not only the osteochondral interface has a complex structure, but its
cartilaginous component has three separate structural zones with depth-
dependent composition and organization. 159 To engineer such spatial
complexity of zonal gradients of articular cartilage, recapitulating the gra-
dients in regulatory signals, required to drive the spatial changes in stem cell
differentiation during development and maturation, is essential. This was
obtained by modulating the mechanical environment and oxygen tension