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International Journal of Bioprinting Preparation and characterization of branched NGCs

similar trend in both groups. These results indicated that arms or legs. While traditional linear NGCs are effective
the regenerated nerves in MBNs exhibited a functional in promoting nerve regeneration, they may damage
recovery comparable to that observed in the traditional the branch points, thereby inadequately addressing
NGC (Figure 4e and f). denervated tissue atrophy. 58,59 In contrast, branched NGCs
Meanwhile, morphological observations of the present a novel approach to clinically treating peripheral
regenerated nerves in the MBN group revealed that they nerve injuries by eliminating the impact of branch points.
filled the triangular area of the proximal connector and Recent studies have reported various branched NGCs for
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elongated into branch channels, forming tiny branches branched peripheral nerve regeneration. However, the
(Figure 4b and g). The average number of regenerated nerve architectural design principles governing branched NGCs
branches was 6 across all rats, smaller than the pre-designed warrant further exploration.
MBN channels. In the central channels of MBN, nerves Consequently, our study aims to promote the rational
regenerated into tiny nerve branches spanning the entire design of branched NGCs by investigating the effect of
channel, while in side channels, no tiny nerve branches branch angle and number on nerve regeneration. In
formed across the channel. The regenerated branched nerves this study, we established a linear sciatic nerve defect
formed within the channels extending from the center of model, marking the first exploration of the design of
the conduit exhibited a gradual reduction in diameter as the branch angle and number for branched NGCs. By
they progressed toward both sides. The middle segment eliminating the influence of different nerve stumps, this
possessed the largest diameter, denoted as B1, while those method proves beneficial for investigating additional
on both sides were labeled B2 and B3, respectively, as shown architecture parameters for branched NGC design.
in Figure 4b. Specifically, a statistically significant difference Within the scope of dual-branched NGCs featuring
in diameter was observed between B1 and B2/B3 (Figure varying branch angles, we observed comparable
4h), suggesting that nerve regeneration within the scaffold histological morphologies and physiological functions
channel is influenced by the distance from the channel to of the regenerated branched nerves. These findings
the center axis of the NGC. suggest that the branch angle of NGCs has minimal
Furthermore, histological analysis was conducted impact on nerve regeneration. While previous studies
to assess the regenerated multi-branched nerves using have often designed branched NGCs with a branch angle
H&E and LFB staining (Figure 4i and j). H&E staining replicating the anatomical structure of injured nerves,
revealed the formation of inner branches within the our study suggests that the branch angle design may
regenerated nerves, while LFB staining provided evidence not be limited to anatomical considerations, offering
of myelination in these regenerated nerves. The results also potential flexibility to meet surgical needs. This aspect
suggested variations in nerve regeneration status among needs to be further explored in future studies.
different tiny channels within the multi-branched NGC. Furthermore, reconstructing nerve branch points in
These findings underscore the notion that the branch array branched nerve regeneration remains a challenge. 61,62 Our
within NGC may contribute to the formation of nerve study presents a novel approach to reconstructing nerve
branches and influence nerve branch regeneration. branch points, demonstrating equivalent functionality in
Together, our investigation reveals that the architectural both branched channels irrespective of the angle. However,
design of branched NGCs affects the nerve branching it should be noted that the number of branches also plays
patterns and functions (Figure 5). The myelinated nerve a crucial role in nerve regeneration. In multi-branched
branches exhibited comparable electrophysiological NGCs, we observed that excessive branching may lead
conduction within the channels of DBNs but demonstrated to limited nerve regeneration in channels on the side of
distinct electrophysiological conduction in MBN. The NGCs. Our findings may be helpful in promoting the
number of branched channels may be implicated in this rational design of the branch number of branched NGCs.
disparity, suggesting that an excess number of branches The fabrication of branched NGCs with complex
could potentially lead to a decrease in nerve conduction. architectural design holds significance for their further
However, further investigation is warranted in the application in addressing branched peripheral nerve
subsequent studies. injuries. Traditional fabrication techniques for branched
NGCs, such as electrospinning, lyophilization, and molding,
4. Discussion face limitations in precision control and architectural
Severe peripheral nerve injuries often result in the replication. 13,14,32,63 Leveraging the advantages of fabricating
disruption of nerve tissues across multiple nerve paths, scaffolds with delicate structures, 3D printing emerges as
leading to functional disabilities in extremities such as the an advanced tool for the fabrication of branched NGCs.
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Volume 10 Issue 3 (2024) 222 doi: 10.36922/ijb.1750