Biomedical Engineering Reference
In-Depth Information
mers have been examined over the past 40 years, materials with optimal
properties which allow for an appropriate host response to ensure func-
tional repair of damaged or diseased tissue and organs are still not avail-
able for many clinical applications. Thus, even well-established synthetically
produced biodegradable polyesters such as PGA, PDLLA, PLLA, and their
copolymers, which are approved for a variety of medical applications, are
not unrivaled with respect to alternative biomaterials. Ultimately, the mate-
rial with the most appropriate properties will become accepted in a specific
biomedical application. The material's processability, mechanical, degrada-
tion, and especially biocompatibility properties, as well as other attributes
relevant to medical implant design (such as sterilizability and sutureability)
will need to be evaluated in context of the application.
Potential uses of P3HB in tissue engineering could be as implants that re-
quire a longer retention time or a higher stability towards the surrounding
environment, but which eventually absorb. Examples of applications could
be in the repair of bone, nerve, the cardiovascular system, or urinary and
gastrointestinal tract defects. P4HB is promising for tissue engineering ap-
plications in the heart and circulatory system. Additionally, the polymer may
replace presently used materials having shorter degradation times, such as
suture materials or surgical textiles. Elastomeric PHAs, such as P3HO-3HH or
P3HB-4HB, could be of interest in the traditional biomedical applications of
elastomers [289]. They also have particularly favorable mechanical properties
when used as scaffolds for repair and regeneration of elastomeric tissue, such
as in the cardiovascular system. Device Master Files for P4HB and P3HB-4HB
have recently been submitted by Tepha Inc. to the FDA, facilitating the devel-
opment of medical products based on these polymers. FDA clearance of the
first PHA device, a P4HB based suture, can be expected by 2006 (Martin DP,
personal communication).
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