博士论文全文发表： Functional tissue engineering of human heart valve leaflets

henryjia

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Functional tissue engineering of human heart valve leaflets, 不错的一篇博士论文！拿来大家分享。# M" D$ J/ |$ i, d" a! U

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The aortic heart valve, situated between the aorta and the left ventricle, is one of the$ w9 r9 O0 ~4 N6 H; b5 l8 F
four valves in the heart controlling the blood flow (chapter 1). It consists of three
7 [1 I. X/ k: {- L4 y* i" T. Ileaflets, with sufficient coaptation areas to ensure closure of the valve. The valve
5 z: r' |# t; l7 W4 dopens and closes about 3.7 billion times in a lifetime, requiring strength, flexibility,
+ i8 O( O; |. X6 j0 sand durability of the tissue. For this imposing function, the leaflets have a highly5 p6 `4 e- k; ]% h) Z7 I/ h
organized and specific tissue structure. When valve function is impaired, for example by calcification of the leaflets or inherited diseases, a live-threatening situation7 M0 C# }2 Z- u! l2 W
occurs as insufficient oxygen is being supplied to the body. A common treatment" s) A6 y' l9 D# J6 X
is the replacement of the aortic valve with either a mechanical valve or a bioprosthetic valve. The durability of a mechanical valve is excellent. However, patients
0 h1 m6 z, ?* G) t4 z3 _5 V* whaving such a valve implanted, require lifelong anticoagulation therapy to prevent, z" r2 K% C! S
thrombo-embolism, the formation of blood clots on the surface of the valve leaflets.
2 O, ?2 F* f9 d* `0 |/ MThis treatment itself results in increased risks of internal bleedings. Patients with a; E+ p2 a% l+ y0 h( |, V1 G
bioprosthetic valve, for example a glutaraldehyde-treated porcine valve or a cryopreserved human donor valve, do not face anticoagulation therapy. The drawback of
+ Y- {; N. N' u+ B& Vthis type of heart valve replacement is that they are less durable caused by enhanced$ \$ R! ?3 A9 x: J
calcification and immune reactions of the body. All heart valve replacements share
" [  d( V8 m( ithe major disadvantage that they are non-living structures and, therefore, not able to
" J" B" \- k( Q$ I# F/ d8 Tgrow, repair and remodel in response to a changing environment, features which are
3 d- [1 X0 S' K/ K. I9 i; k5 rof particular importance in children.! T# B* T0 ]' u8 A/ I" \  d
The ideal heart valve replacement is autologous, engineered from material of the
) ^9 V* b, v% {) B, l# o0 Vpatient itself to prevent immune reactions, and living to be able to grow, repair and
6 k$ Y3 F9 _* C0 Q- zremodel. The emerging field of tissue engineering focuses on the engineering of such
9 ^8 r" d$ a, O7 Jorgans. The principle of tissue engineering is to seed and culture cells from the recipient onto a carrier material, the scaffold, which degrades while the tissue is developing
( z+ b+ r* a5 j) `outside the body (in-vitro). As soon as the tissue properties are sufficient to withstand' r, j/ H# l7 B2 v; j
in-vivo conditions, the tissue can be implanted into the recipient. Heart valve replacements can be engineered according to this principle (chapter 2). Ten years ago, the
+ {5 i) q: M3 u+ vfirst successful replacement of one of the pulmonary valve leaflets by a tissue engineered leaflet was reported in lambs. Nowadays, complete tissue engineered valves' u) f3 i. \4 v) ?; g7 }9 L' I  [
are shown to be fully functional in the pulmonary position in animal studies. The
7 Z: L% ^4 J* F% W$ j$ |! Ppulmonary valve is, however, exposed to lower pressures and flows than the aortic# n+ }% n) m) q5 X1 _' }5 v
valve. A valve, able to resist the pressures and flows in the aortic position has not yet8 c) d+ b) c! F6 K6 K: P) @
been created, using the principle of tissue engineering and a relatively fast degrading
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botizhou

Thanks.

henryjia

求助版主：我似乎发错地方了，能否麻烦版主转到心脏干细胞专区。多谢！