Artificial Scaffolds and Mesenchymal Stem Cells for Hard Tissues - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 163

transdifferentiation processes [ 8 ]. Due to this large differentiation capacity, using
MSCs for autologous transplantations would be possible for several major diseases
such as heart failure and diabetes or degenerative diseases such as bone defects.
Furthermore, MSCs seem to be not only hypoimmunogenic and thus suitable for
allogenic transplantation [ 66 ], but they are also able to induce immunosuppression
upon transplantation [ 81 ].
Another group of adult SCs which has attracted attention is ectomesenchymal
SCs, derived from oral tissues. This SC group includes dental pulp stem cells
(DPSCs) and stem cells of human exfoliated deciduous teeth (SHEDs), both
deriving from the pulpa, dental periodontal ligament stem cells (DPLSCs), dental
follicle cells (DFCs) and stem cells from the apical papilla (SCAPs). These
dental-derived progenitor cells or SCs have the potential to differentiate into
dental cell types, such as ameloblasts, odontoblasts or cementoblasts. These
properties make them valuable tools for dental regenerative medicine. In addi-
tion, it has been shown that some of these cells can also differentiate into
osteoblasts or chondroblasts [ 82 ], which makes them valuable for additional,
more general approaches in regenerative medicine. One major branch of research
focuses on SC-based tissue engineering for the reconstruction of large bone
defects and the osseointegration of tooth implants. This is also the topic of the
following sections.
3 Scaffolds for Bone Regeneration
It is widely acknowledged that for the repair of musculoskeletal disorders such as
bone defects and dental implants, tissue engineering approaches have to combine
cells capable of osteogenic activity with an appropriate scaffolding material.
Optimal bio-engineered scaffolds have to provide appropriate initial mechanical
properties, promote the formation of new bone, and be gradually, evenly and
homogeneously degraded without causing significant inflammatory responses or
genetic alterations, in parallel allowing the new bone to remodel and assume the
mechanical support function.
The biomaterials existing to date are not sufficiently optimized, in particular
regarding the control of MSC differentiation. Consequently, there is an urgent need
to design tissue-engineered scaffolds that offer an improved level of functionality
over those currently available, adapted to be functionalized and to have direct
influence on MSC growth and differentiation. For SC-directed bone repair to be
clinically successful, a scaffold must be identified and optimized to support not
only cellular adhesion and recruitment, but specifically also osteoinduction and
osteoconduction. In the following, fundamental studies and recent results are
summarized for scaffold material design, conventional and novel fabrication
methods, and surface modification technologies. Particular focus is given to the
influence of polymer scaffolds on adhesion and differentiation of hMSC.