Bioreactor for Dynamic Flexural Stimulation
Background
Dynamic flexure is a major mode of deformation in
the native heart valve cusp, and may effect the mechanical
and biological development of tissue engineered heart
valves (TEHV). This novel bioreactor was developed
to study the effect of dynamic flexural stimulation
on TEHV biomaterials. It has been implemented in a
study to compare the effect of uni-directional cyclic
flexure on the effective stiffness of two candidate
TEHV scaffolds: a non-woven mesh of polyglycolic acid
(PGA) .bers, and a non-woven mesh of PGA and poly l-lactic
acid (PLLA) fibers, both coated with poly 4-hydroxybutyrate
(P4HB).
Device Operation
The bioreactor consists of two
identical chambers (127mm_101.6 mm),
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| Bioreactor
for Dynamic Flexural Stimulation |
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| Bioreactor
operating inside a standard cell culture incubator
at 37_C and 5% CO2. The bioreactor consists of
two parallel chambers secured to a base plate and
coupled via a cross-arm to a centrally positioned
linear actuator. |
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each containing
6 culture wells (25.4mm
diameter, 16mm deep). Situated within each well are
four stainless-steel ‘‘stationary posts’’ arranged
orthogonally around a central channel in the floor
of the culture well. The device can accommodate a total
of 12 rectangular samples (maximum dimensions approximately
25mm_7.5mm_2 mm), with each sample being positioned
between the four stationary posts, orthogonal to the
central channel. The structural elements of the device
were machined from polysulfone, chosen for its excellent
thermal and chemical stability, and abrasion-resistant
acrylic, which provides good optical transparency.
Dynamic flexural stimulation can
be applied to each of the samples in the form of
cyclic three-point flexure
by an environmentally sealed linear actuator. The piston
of the actuator is rigidly coupled to a cross arm in
the form of a T-junction. Conversely, the cross-arm
is rigidly coupled to the arm of each chamber. Each
arm bifurcates and extends into a chamber (two penetrations
per chamber). Both arms terminate in six fingers through
which ‘‘flexure pins’’ can
be inserted to bracket the rectangular samples in the
middle. Therefore, each sample can be subjected to
uni-directional or bi-directional three-point flexure.
Frequency, amplitude, acceleration, and deceleration
profiles can be developed using Windows-based Si Programmer
software (Applied Motion Products, Watsonville, CA).
The structural elements of the device can be cold gas
sterilized by ethylene oxide, and the entire device
was designed to be operated inside of a standard humidified
incubator.
For more information, please see the
following article:
[1] Engelmayr, G.C., Hildebrand,
D.K., Sutherland, F.W.H., Mayer, J.E., Sacks, M.S.
A novel bioreactor
for the dynamic flexural stimulation of tissue engineered
heart valve biomaterials. Biomaterials 24 (2003) 2523–2532
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