Fabrication and Characterization of Polycaprolactone/Chitosan—Hydroxyapatite Hybrid Implants for Peripheral Nerve Regeneration

Abstract

Major efforts for the advancement of tubular-shaped implant fabrication focused recently on the development of 3D printing methods that can enable the fabrication of complete devices in a single printing process. However, the main limitation of these solutions is the use of non-biocompatible polymers. Therefore, a new technology for obtaining hybrid implants that employ polymer extrusion and electrophoretic deposition is applied. The fabricated structures are made of two layers: polycaprolactone skeleton and chitosan–hydroxyapatite electrodeposit. Both of them can be functionalized by incorporation of mechanical or biological cues that favor ingrowth, guidance, and correct targeting of axons. The electrodeposition process is conducted at different voltages in order to determine the influence of this process on the structural, chemical, and mechanical properties of implants. In addition, changes in mechanical properties of implants during their incubation in phosphate-buffered solution (pH 7.4) at 37 °C up to 28 days are examined. The presented technology, being low-cost and relatively simple, shall find a broad scope of applications in customized nerve tissue engineering.

Controlling the Spatiotemporal Release of Nerve Growth Factor by Chitosan/Polycaprolactone Conduits for Use in Peripheral Nerve Regeneration

“…The method developed in our laboratory allows extruding the PCL fiber in helix form with predefined geometry (i.e., pitch, fiber diameter) ( Figure 4 A) [ 8 ]. Moreover, the pitch can be constant or gradient ( Figure 4 A).…”

“…This highly complex network provides control over sensation, movement, and motor coordination. Treatment of damaged peripheral nerve tissue may be pharmacologic, by transplantation (i.e., autografting, allografting, or xenografting) or by the implantation of nerve guidance conduits (NGCs) to bridge the nerve stumps, providing room and environment for nerve regeneration [ 5 , 6 , 7 , 8 ]. Conventional pharmacologic therapy is performed in the early stages of damage caused by inflammation.…”

“…A technology for obtaining chitosan/polycaprolactone nerve guidance conduits, which employs polymer extrusion and electrophoretic deposition, was developed in our laboratory [ 8 ]. The fabricated structures were made of two layers: polycaprolactone (PCL) helix and chitosan (CH) hydrogel deposit.…”

Nanohydroxyapatite as a Biomaterial for Peripheral Nerve Regeneration after Mechanical Damage—In Vitro Study

“…The XRD patterns show the main diffraction peaks of the apatite phase with hexagonal structure (P6 3 /m, No. 176) at 2θ (hkl) equal to 25 1 shows the calculated lattice parameters (a = b and c) and cell volume (V) for both materials, indicating cell growth induced by Li + ions and, on the other hand, cell contraction after further Eu 3+ substitution. The calculated cell parameters were in good correlation with the results observed for the (0 0 2) plane shift.…”

“…Moreover, nHAp did not neutralize the electrophysiological activity of neurons, as Liu et al demonstrated in primary cultures of rat neurons [ 23 ]. Currently, nanotubes made in 3D printing technology from combined materials containing hydroxyapatite are also being studied [ 24 , 25 ]. In vivo studies have shown that nHAp has a beneficial effect on nerve regeneration in rats after prior spinal distension.…”