Manufacture of multimicrotubule chitosan nerve conduits with novel molds and characterization in vitro

Abstract

Multimicrotubule chitosan conduits (M-conduits) were fabricated using novel molds and a thermal-induced phase-separation technique. Hollow chitosan conduits (H-conduits) with an inner diameter of 1-5 mm and a wall thickness of 0.2-1.0 mm were made, and then a novel mold composed of a styrofoam insulating pedestal with several holes and a stainless steel cover plate was used to make M-conduits. In brief, corresponding H-conduits were inserted upright into the holes of the styrofoam pedestal, and filled with chitosan solution, then rapidly covered with the precooled stainless steel cover plate, and then placed in a freezer. The styrofoam insulating pedestal enclosing the conduits could reduce the heat transfer through the side wall of the conduits. Gradual phase separation then occurred uniaxially in the presence of a unidirectional temperature gradient from the top end to the bottom end of the chitosan conduits. The phase-separated polymer/solvent systems were then dried in a freeze-dryer. The microtubule diameters were controlled by adjusting the polymer concentration and cooling temperature. In vitro characterization demonstrated that the mold-based multimicrotubule chitosan conduits possessed suitable mechanical strength, microtubule diameter distribution, porosity, swelling, biodegradability, and nerve cell affinity, and so they showed potential for application as nerve tissue engineering scaffolds.

A novel basic fibroblast growth factor delivery system fabricated with heparin-incorporated fibrin–fibronectin matrices for repairing rat sciatic nerve disruptions

“…The chitosan conduit had been characterized previously (Ao et al 2006), including mechanical strength, porosity, swelling, biodegradability, and nerve cell affinity. Chitosan is a cationic natural biopolymer produced by alkaline N-deacetylation of chitin, the most abundant natural polymer after cellulose.…”

“…The methods used to prepare the hollow chitosan conduits have been previously described (Ao et al 2006). The fibrin glue used was a fibrinogen-based product (Guangzhou Bioseal Biotech, Guangzhou, China).…”

Recent Strategies in Tissue Engineering for Guided Peripheral Nerve Regeneration

“…Weak degradability Myelinated axons [50] Low structural integrity Muscular potential [51] Infl ammatory [52] Collagen Biocompatible Partially recovered nerve functionality [53] Degradable [54] Fragile Fibrin Easily manipulated Glial cell invasion [55] Angiogenic Axonal growth [56] Fibronectin Low structural integrity Growth of fi broblasts and Schwann cells [57] Gelatin Low structural integrity Unmyelinated axons [58] Economic Excrescence [59] Proliferation of Schwann cells Keratin Biocompatible Improved density and size of axons [60] Improved conduction [61] Silk Fibroin Biodegradable Mildly infl ammatory [62] Biocompatible Nervous tissue colonization [63] High structural integrity [64] studies, particularly with Neuragen and Neurotube, are often comparable to autografts in the treatment of lesions with a maximum length of 3 cm and a small diameter. Unfortunately, these models do not assure nerve regeneration in more extensive lesions or in larger nerves.…”

The Use of Chitosan-Based Scaffolds to Enhance Regeneration in the Nervous System

“…Moreover, immunophilin FK506 combined with biodegradable chitosan guide provides neurotrophic and neuroprotective actions, promoting nerve regeneration in a rat sciatic nerve defect model . Also neurosteroids, such as progesterone (PROG) and pregnenolone (PREG), have been used for potentiating conduit nerve repair as these hormones are synthesized by SCs (Baulieu & Schumacher, 2000) and induce myelination binding on intracellular receptors which activate the synthesis of myelin protein P0 and PMP22 (Desarnaud et al, 1998;Jung-Testas, Schumacher, Robel, & Baulieu, 1996). Furthermore, neurite outgrowth may be stimulated by a PROG metabolite (5-a-tetrahydroprogesterone) through GABA(A) receptors (Guennoun et al, 2001;Koenig, Gong, & Pelissier, 2000).…”

“…Commercial chitins are usually isolated from marine crustaceans, because of large amount of waste derived from food processing. In this case, a-chitin is produced while squid pens are used to produce b-chitin (Aranaz et al, 2009). Crustacean shells consist of proteins, calcium carbonate, chitin, and contain pigments such as carotenoids.…”