Interaction of Cells with Decellularized Biological Materials - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 113

Fig. 2 Patients developing
antibodies after implantation
of homografts or
decellularized homografts.
Homografts: open diamonds
class I, filled diamonds class
II (Hawkins et al. [ 59 ]); open
triangles class I, filled
triangles class II (Hawkins
et al. [ 63 ]); open squares
panel reactive antibodies
(Shaddy et al. [ 52 ]); filled
squares panel reactive
antibodies with DDT
(Shaddy et al. [ 52 ]).
Decellularized homografts:
open circles class I, filled
circles class II (Hawkins
et al. [ 59 ]); asterisks class I
(Elkins et al. [ 43 ])
Bechtel et al. [ 58 ] compared the immunological data from 24 CryoValve SG
recipients with the data from 22 patients who had received a standard cryopre-
served homograft. No anti-HLA antibodies were detectable in the CryoValve SG
group between months 1 and 6 after surgery. But 66% of the homograft recipient
group patients developed positive HLA titers [ 58 ]. The data are consistent with the
findings of Hawkins et al. [ 59 ].
Improper decellularization seems to be one major factor for the fatal outcomes
of decellularized porcine heart valves [ 25 ]. Significant cellular components were
still detectable [ 60 ]. Other decellularized porcine heart valves have produced
unsatisfactory clinical results, as they are repelled relatively quickly [ 61 ].
Numerous publications of clinical data have shown a reduced immunogenicity
of decellularized human tissue [ 55 - 59 , 62 , 63 ]. The depletion of the immunogenic
cellular components by the decellularization process in vivo leads to a significant
decrease of HLA class I and HLA class II antibody stimulation compared with
conventional homografts (and compared with xenogeneic matrices) and thus to a
better acceptance by the immune system. This is an important basis for long-term
durability of heart valve replacements.
7 Conclusion
The shortcomings of all known alloplastic implant materials, namely, infectious and
thrombembolic complications, blazed a trail for biological and bioartificial tissue
substitutes. However, although these grafts found their way into clinical practice and
improved methods for tissue decellularization were established over the last few