Fig 1.
The system of lamination of the MCS (Bio-3D printer) (A) skewers the MCSs into needle-array according to a three-dimensional structure pre-designed on a computer system (C).
It is possible to design a 3D tube-shaped structure, such as that plotted in green (B), on the workstation computers.
Fig 2.
The schematic illustration of the bioreactor system (A).
The vascular graft generated by the Bio-3D printer is cannulated by an outer 22 gauge intravenous catheter (SURFLO: Termo, Tokyo, Japan) which has side holes, and is perfused by culture medium for 2 days before implantation. A scaffold-free vascular graft is generated from the MCSs(B).
Fig 3.
An intra-operative photograph of end-to-end anastomosis between the tubular structure and the abdominal aorta of the nude rat (A).
Color Doppler (left) and pulse Doppler (right) flow imaging of percutaneous ultrasonography show patent vessels on the fifth day after implantation (B).
Fig 4.
A phase contrast microscopy shows the spheroid morphology of a MCS (A).
Spindle to polygonal cells are mixed in the MSC (B). Masson’s trichrome staining reveals the extensive collagenous extracellular matrix (ECM) as blue (C). vWF, CD31 and CellTracker Red-positive vascular endothelial cells are distributed to all parts of the MCS (D-F). SMA and desmin-positive HASMC intermingle with the other cell types (G,H).
Fig 5.
Histological examination of the vascular graft in a short axis cross-section (Pre-implantation).
Hematoxylin and eosin staining reveals the internal and external margins are smooth and the pinhole by the pinholder are completely closed (A). Masson’s trichrome staining reveals the extensive collagenous ECM as blue (B). vWF (C) and CD31-positive vascular endothelial cells (D) are distributed to all parts of the graft.
Fig 6.
Remodeling of the blood vessel (Post-implantation).
The graft of post-implantation is patent and remodeled (A). The wall area and lumen area pre-implantation are shown in blue, post-implantation in red (B). The lumen area is enlarged (P = 0.032) and the wall area is decreased (P = 0.008) after implantation. The total wall area and lumen area shows no significant difference (C).
Fig 7.
Histological examination of the luminal side of the vascular graft.
At pre-implantation, the vascular endothelial cells distribute to the entire area of the graft. Conversely, after implantation, vWF, CD31 and CellTracker Red-positive endothelial cells are seen at the inner lumen of the vessel. Furthermore, the vascular endothelial cells cover the inner surface of the vessel more continuously on the fifth day than on the second day.
Fig 8.
The rat aortae were stained with HE and CD31, respectively (A).
The number of endothelial cells in the five rat aortae was counted and compared with those in the tubular tissues (B).