Intravital molecular imaging of small-diameter tissue-engineered vascular grafts in mice: a feasibility study.
OBJECTIVE
Creating functional small-diameter tissue-engineered blood vessels has not been successful to date. Moreover, the processes underlying the in vivo remodeling of these grafts and the fate of cells seeded onto scaffolds remain unclear. Here we addressed these unmet scientific needs by using intravital molecular imaging to monitor the development of tissue-engineered vascular grafts (TEVG) implanted in mouse carotid artery.


RESULTS
Green fluorescent protein-labeled human bone marrow-derived mesenchymal stem cells and cord blood-derived endothelial progenitor cells were seeded on polyglycolic acid-poly-L-lactic acid scaffolds to construct small-caliber TEVG that were subsequently implanted in the carotid artery position of nude mice (n = 9). Mice were injected with near-infrared agents and imaged using intravital fluorescence microscope at 0, 7, and 35 days to validate in vivo the TEVG remodeling capability (Prosense680; VisEn, Woburn, MA) and patency (Angiosense750; VisEn). Imaging coregistered strong proteolytic activity and blood flow through anastomoses at both 7 and 35 days postimplantation. In addition, image analyses showed green fluorescent protein signal produced from mesenchymal stem cell up to 35 days postimplantation. Comprehensive correlative histopathological analyses corroborated intravital imaging findings.


CONCLUSIONS
Multispectral imaging offers simultaneous characterization of in vivo remodeling enzyme activity, functionality, and cell fate of viable small-caliber TEVG.
Hjortnaes
Jesper
J
Center for Molecular Imaging Research , Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Gottlieb
Danielle
D
Figueiredo
Jose-Luiz
JL
Melero-Martin
Juan
J
Kohler
Rainer H
RH
Bischoff
Joyce
J
Weissleder
Ralph
R
Mayer
John E
JE
Aikawa
Elena
E
D000818:Animals; D001807:Blood Vessel Prosthesis; D005240:Feasibility Studies; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000494:pharmacology; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D011091:Polyesters; D011100:Polyglycolic Acid / Q000494:pharmacology; D011108:Polymers / Q000494:pharmacology; D019919:Prosthesis Implantation; D015203:Reproducibility of Results; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry; D014162:Transfection
D011091:Polyesters; D011108:Polymers; D049452:Green Fluorescent Proteins; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)