Fabrication and Evaluation of PLLA Multichannel Conduits with Nanofibrous Microstructure for the Differentiation of NSCs In Vitro

Abstract

Nerve conduits (NCs) with multiple longitudinally aligned channels, being mimicking the natural nerves anatomical structure, have been attracted more and more attentions. However, some specific structural parameters of a conduit that would be beneficial for further improvement of neural tissue regeneration were not comprehensively considered. Using a systematized device and combining low-pressure injection molding and thermal-induced phase separation, we fabricated 33-channel NCs (outer diameter 3.5 mm, channel diameter 200 mm) with different well-defined microscopic features, including NCs with a nano-fibrous microstructure (NNC), NCs with microspherical pores and nano-fibrous pore walls (MNC), and NCs with a ladder-like microstructure (LNC). The porosities of these NCs were *90% and were independent of the fine microstructures, whereas the pore size distributions were clearly distinct. The adsorption of bovine serum albumin for the NNC was a result of having the highest specific surface area, which was 3.5 times that of the LNC. But the mechanical strength of NNC was lower than that of two groups because of a relative high crystallinity and brittle characteristics. In vitro nerve stem cells (NSCs) incubation revealed that 14 days after seeding the NSCs, 31.32% cells were Map2 positive in the NNC group, as opposed to 15.76% in the LNC group and 23.29% in the MNC group. Addition of NGF into the culture medium, being distinctive specific surface area and a high adsorption of proteon for NNC, 81.11% of neurons derived from the differentiation of the seeded NSCs was obtained. As a result of imitating the physical structure of the basement membrane of the neural matrix, the nanofibrous structure of the NCs has facilitated the differentiation of NSCs into neurons.

Fundamentals and Current Strategies for Peripheral Nerve Repair and Regeneration

“…4 shows some promising results considering synthetic biomaterials applied to PNR. From Table 4, it is also possible to find the most recent and relevant reports considering the use of synthetic biomaterials in PNR [87][88][89][90][91][92][93][94][95][96][97][98][99].…”

“…PLLA is the crystalline form of PLA. In a study by Zeng et al [89], several topographies were achieved in the PLLA conduit using low-pressure injection molding and thermal-induced…”

Advances in Controlling Differentiation of Adult Stem Cells for Peripheral Nerve Regeneration

“…In a similar study, PLLA based conduits with nanofibrous structure and microchannels along with higher surface area and lower mechanical strength induced neuronal differentiation of NSCs compared to microporous and ladder-like structures. [211] In addition to the microchannels, longitudinal fibers or surface micropatterns have also been used to provide guided axonal growth and stem cell differentiation. It was reported that changing the alignment, diameter, and surface properties of electrospun PCL microfibers promoted the differentiation of stem cells into Schwann cells or neurons, the secretion of neurotrophins and dictated the morphology and alignment of the derived cells.…”

Nano-Engineered Environment for Nerve Regeneration: Scaffolds, Functional Molecules and Stem Cells

“…In the study of Yang et al, [15] NSCs can progressively grow, migrate and differentiate into neurons throughout a PLLA 3D scaffold fabricated by TIPS. Moreover, multi-channel conduits can be prepared by combining low-pressure injection molding and TIPS, thereby showing great potential applications in nerve-tissue engineering [31,32]. However, polymer crystallization in the liquid solvent during phase separation is the precondition to prepare nanofibrous scaffolds.…”