Cardiac tissue engineering in an in vivo vascularized chamber.
BACKGROUND
Cardiac tissue engineering offers the prospect of a novel treatment for acquired or congenital heart defects. We have created vascularized pieces of beating cardiac muscle in the rat that are as thick as the adult rat right ventricle wall.


RESULTS
Neonatal rat cardiomyocytes in Matrigel were implanted with an arteriovenous blood vessel loop into a 0.5-mL patented tissue-engineering chamber, located subcutaneously in the groin. Chambers were harvested 1, 4, and 10 weeks after insertion. At 4 and 10 weeks, all constructs that grew in the chambers contracted spontaneously. Immunostaining for alpha-sarcomeric actin, troponin, and desmin showed that differentiated cardiomyocytes present in tissue at all time points formed a network of interconnected cells within a collagenous extracellular matrix. Constructs at 4 and 10 weeks were extensively vascularized. The maximum thickness of cardiac tissue generated was 1983 microm. Cardiomyocytes increased in size from 1 to 10 weeks and were positive for the proliferation markers Ki67 and PCNA. Connexin-43 stain indicated that gap junctions were present between cardiomyocytes at 4 and 10 weeks. Echocardiograms performed between 4 and 10 weeks showed that the tissue construct contracted spontaneously in vivo. In vitro organ bath experiments showed a typical cardiac muscle length-tension relationship, the ability to be paced from electrical field pulses up to 3 Hz, positive chronotropy to norepinephrine, and positive inotropy in response to calcium.


CONCLUSIONS
In summary, the use of a vascularized tissue-engineering chamber allowed generation of a spontaneously beating 3-dimensional mass of cardiac tissue from neonatal rat cardiomyocytes. Further development of this vascularized model will increase the potential of cardiac tissue engineering to provide suitable replacement tissues for acquired and congenital defects.
Morritt
Andrew N
AN
Bernard O'Brien Institute of Microsurgery, 42 Fitzroy St, Fitzroy, 3065 Victoria, Australia.
Bortolotto
Susan K
SK
Dilley
Rodney J
RJ
Han
XiaoLian
X
Kompa
Andrew R
AR
McCombe
David
D
Wright
Christine E
CE
Itescu
Silviu
S
Angus
James A
JA
Morrison
Wayne A
WA
D000199:Actins / Q000378:metabolism; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001808:Blood Vessels / Q000166:cytology / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D049109:Cell Proliferation; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism; D003893:Desmin / Q000378:metabolism; D015194:Diffusion Chambers, Culture / Q000379:methods*; D019394:Ki-67 Antigen / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D023822:Tissue Engineering / Q000295:instrumentation* / Q000379:methods*; D014336:Troponin / Q000378:metabolism
D000199:Actins; D000316:Adrenergic alpha-Agonists; D018031:Connexin 43; D003893:Desmin; D019394:Ki-67 Antigen; D018809:Proliferating Cell Nuclear Antigen; D014336:Troponin; D002118:Calcium; D009638:Norepinephrine