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International Journal of Bioprinting 3D printing with drug for vascular repair

fabricated ABV, we conducted an experiment to validate the 3D-printed ABVs incorporating cells and drug-loaded
the blood flow through ABV, and verified that blood vessels nanoparticles was assessed. The animal model of hindlimb
were capable of reliable, sustained blood flow (Figure 4E). ischemia created in this study was subjected to ABVs
In addition to evaluating fluidity, we also investigated the transplantation, and functional evaluation was performed
impact of cell viability on blood vessel regeneration during (Figure 5A). When only PBS without cells or ABVs were
the transplantation of cell-loaded ABV. Cell viability transplanted, all hindlimbs of the treated animals were
assessments were performed at multiple time points: 1, 3, found to be necrotic. On the 14th day after transplantation,
and 7 days. The results demonstrated consistent and stable the group transplanted with ABVs without EPC or drug-
cell viability throughout the observation period, indicating loaded nanoparticles showed significant limb recovery
the robustness of the cell-loaded ABVs in maintaining (Figure 5B). During the follow-up period of up to 28 days,
cell integrity and supporting potential tissue regeneration we found that the treatment effect was sustained, similar to
(Figure 4F). Further, mechanical properties of the vascular that observed on the 14th day. Although the NP@BV group
grafts such as burst pressure, compliance, and suture manifested excellent effect, the laser Doppler perfusion
retention were evaluated. In this study, ABVs made from imaging results confirmed that the EPC@NPSC@BV group
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alginate exhibited higher burst pressure values compared on day 14 showed more profound effect. Most importantly,
with those made solely from atelocollagen. However, due to the group transplanted with ABVs, together with cells and
the absence of cell adhesion ligands, an ABV combining nanoparticles, showed the most pronounced effect from
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collagen and alginate was created to address the respective the 7th day after transplantation (Figure 5C). This strong
drawbacks of both materials (Figure 4G). Subsequently, therapeutic effect on the hindlimb was attributed to both
burst pressure measurements were conducted to assess the cells and ABVs. The efficacy of vascular endothelial
the burst pressure of cell-laden or cell-free ABVs, which cells is an important factor contributing to the recovery
were cultured for 7 days. The groups with cell-laden ABVs of hindlimb over time; however, EPC@NPSC@BV
(i.e., EPC@NPS@BV, EPC@NPC@BV, EPC@NPSC@ outperformed other counterparts in terms of the speed of
BV) exhibited an improvement in burst pressure of more recovery and the amount of blood flow during the recovery
than threefold compared to the cell-free ABV group (i.e., period. We also analyzed foot necrosis after transplantation
NP@BV) (Figure 4H). Next, to confirm continuous cell (Figure 5D). Similar to the findings mentioned earlier,
growth within the ABVs, fluorescence immunostaining the highest incidence of necrosis was observed in the
was employed to assess the expression of essential EPC PBS and EPC groups. Notably, however, the EPC@NP@
markers, such as CD31 and VE-cadherin (Figure 4I). BV and EPC@NPSC@BV groups exhibited the most
Additionally, the protein-level expression of CD31 and Ki- promising therapeutic outcomes, promoting limb recovery
67 was compared to that of two-dimensional (2D)-cultured significantly faster than other groups (Figure 5E). This
EPCs. It is noteworthy that when transitioning from a 2D result is supported by the highest expression of α-SMA and
CD31, which are vascular-related markers, observed in the
culture to a 3D culture environment, we observed a notable EPC@NPSC@BV group (Figure 5F–I). In the final part
increase in the expression of endothelial cell-related of the experiment, we determined the presence of ROS
markers (Figure 4J). This expression increase of these generation within the tissue through DHE staining. We
markers underscores the capacity of 3D culture systems observed a significant reduction in DHE-positive staining
in establishing a more physiologically relevant cellular in the EPC@NPSC@BV group, consistent with the staining
environment. Unlike traditional 2D cultures, 3D cultures results for markers associated with blood vessels (Figure
better mimic the natural microenvironment of cells S2A and S2B in Supplementary File). Taken together, these
within tissues and organs, allowing for improved cell–cell results collectively suggest the potential utility of ABVs
interactions and the formation of complex cell structures. incorporating drug-loaded nanoparticles and EPCs in
In this context, the enhanced expression of endothelial mitigating the severity of ischemic diseases.
cell-related markers suggests that our 3D culture model
provides a more suitable platform for studying endothelial 4. Discussion
cell behavior and function.
Despite the advancements in drug therapy and surgical
3.4. In vivo transplantation of artificial blood vessels procedures for the treatment of vascular diseases, several
incorporating drugs-loaded nanoparticles in animal notable disadvantages inherent in these approaches
model limit their long-term effectiveness. Drug therapy, while
Based upon the aforementioned results, we conducted offering preventive benefits, often requires continuous
in vivo experiments to validate the effects of drugs administration, which may lead to side effects or drug
encapsulated in nanoparticles. Furthermore, the stability of resistance over time. Moreover, drug therapies may not

Volume 10 Issue 2 (2024) 341 doi: 10.36922/ijb.1857