Biomedical Engineering Reference
In-Depth Information
unique biomechanical properties of tendon tissues. Therefore, the
parallelalignmentstructureandstrongmechanicalpropertyshould
be considered for tendon scaffold design. It was proposed that an
ideal tendon scaffoldshould fulfill the followingrequirements
9
:
1. Biodegradability withadjustable degradation rate
2. Biocompatibility before, during, and after degradation
3. Superior mechanical properties and maintenance of mechanical
strength during the tissue regeneration process
4. Biofunctionality: The ability to support cell proliferation and dif-
ferentiation, ECMsecretion, and tissueformation
5. Processability: The ability to be processed to form desired con-
structs of complicated structures and shapes, such as woven or
knitted scaffolds, etc.
As early as 1994, Cao
et al
. performed a pioneer research study
of tendon engineering by using unwoven PGA fibers as the scaf-
fold for
in vivo
tendon engineering in a nude mouse model.
10
First,
unwoven PGA fibers were arranged in a parallel fashion, and then
tenocytes isolated from calf tendons were seeded onto the scaffold
followed by
in vivo
implantation in the subcutaneous tissue of nude
mice. After 12 weeks of implantation, tendonlike tissue formed and
revealed longitudinally aligned collagen fibers. Afterward, the same
scaffold was used for engineering tendons in immunocompetent
animals.
In the first experiment, a hen claw was used as a model for ten-
don regeneration and repair inside a tendon sheath. First, autolo-
gous tenocytes were isolated and seeded onto unwoven PGA fibers
and the cell-scaffold construct was
in vitro
-cultured for one week
followedby
in vivo
transplantationtorepaira3cmlongdefectofthe
flexor digitorum profundus tendon. At 14 weeks' postrepair, mature
tendon tissue was formed when observed grossly (Fig. 34.1,
top
).
Histologically, longitudinally aligned collagen fibers with a curving
pattern could be observed as well (Fig. 34.1,
middle
) similar to that
of the nativetendon (Fig. 34.1,
bottom
).
More importantly, the engineered tendon reached 83% of the
native tendon's tensile strength.
11
In the second experiment, a
porcine model was used to perform the study. However, dermal
Search WWH ::
Custom Search