Synthesis of Layered, Graded Bioscaffolds - Structural Interfaces and Attachments in Biology - page 355

the wound site in vivo [ 76 , 77 ]. Both groups showed dramatic increases in cell
number and metabolic activity at day 7. After 14 days of culture there were no
significant differences between the groups in tendon cell proliferation or metabolic
activity (Fig. 16.9a-b ), indicating that the core-shell constructs have adequate
permeability to support the nutrient and metabolite transport necessary for
sustained cell viability and proliferation.
16.5 Conclusions
Porous, 3D biomaterials have been used extensively for a variety of tissue engineering
applications, primarily as analogs of the ECM capable of inducing regeneration of
damaged tissues and organs. CG scaffolds are an important class of these materials
that have been applied as regeneration templates for a wide variety of wounds. Here,
two new classes of CG scaffolds were described. First we described multi-
compartment CG scaffolds, where distinct regions of the scaffold can contain distinct
compositional, mechanical, and microstructural properties. Notably, a liquid phase
co-synthesis method has been created to allow these distinct scaffold compartments
to be linked via a continuous interface. The second class of materials are scaffold-
membrane CG composites; here CG membrane structures were integrated into the
scaffold structure in order to significantly improve the mechanical competence of a
CG scaffold without sacrificing scaffold porosity. In both cases, modeling
frameworks were introduced in order to better understand the observed changes in
microstructural andmechanical parameters. Additionally, in the case of the first class
of composites it was important to explore methodologies that allow regional charac-
terization of the scaffold due to the heterogeneous nature of thematerial. Both classes
of materials should also be amenable to integration with photolithographic
techniques recently developed in our laboratory to immobilize distinct groups of
biomolecules within CG scaffolds in a spatially defined manner [ 78 ]; this approach is
expected to facilitate creation of gradient and compartment-specific biomolecular
(i.e., growth factors, ligands) patterns within these and other CG scaffold variants.
Overall, the materials described here provide an exciting basis for future experiments
targeted at developing regeneration templates for orthopedic interfaces as well as
other classes of gradient and interfacial tissues.
Acknowledgments This work was supported in part by the NSF IGERT 0965918 (DWW), the
Chemistry-Biology Interface Training Program NIH NIGMS T32GM070421 (SRC), the Chemical
and Biomolecular Engineering Dept. (DWW, SRC, BAH), and the Institute for Genomic Biology
(DWW, SRC, BAH) at the University of Illinois at Urbana-Champaign. We wish to acknowledge
the assistance of Rebecca Yapp, Yue Wang, and Dr. Michael Insana (UIUC) for assistance with
ultrasound elastography-based analyses as well as Manuel Ramirez for assistance in CG mem-
brane fabrication and characterization. Research described in this manuscript was carried out in
part at the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois,
which are partially supported by the US Department of Energy under grants DE-FG02-07ER46453
and DE-FG02-07ER46471.