Enhanced peripheral nerve regeneration by the combination of a polycaprolactone tubular prosthesis and a scaffold of collagen with supramolecular organization

Abstract

The purpose of this study was to investigate the influence of implanting collagen with a supramolecular organization on peripheral nerve regeneration, using the sciatic nerve tubulization technique. For this purpose, adult female Sprague Dawley rats were divided into five groups: (1) TP – sciatic nerve repaired with empty polyethylene tubular prothesis (n = 10), (2) TPCL – nerve repair with empty polycaprolactone (PCL) tubing (n = 8), (3) TPCLF – repair with PCL tubing filled with an implant of collagen with a supramolecular organization (n = 10), (4) AG – animals that received a peripheral nerve autograft (n = 8), and (5) Normal nerves (n = 8). The results were assessed by quantification of the regenerated fibers, nerve morphometry, and transmission electron microscopy, 60 days after surgery. Immunohistochemistry and polarization microscopy were also used to analyze the regenerated nerve structure and cellular elements. The results showed that the AG group presented a larger number of regenerated axons. However, the TPCL and TPCLF groups presented more compact regenerated fibers with a morphometric profile closer to normal, both at the tube midpoint and 2 mm distal to the prosthesis. These findings were reinforced by polarization microscopy, which indicated a better collagen/axons suprastructural organization in the TPCLF derived samples. In addition, the immunohistochemical results obtained using the antibody anti-p75NTR as a Schwann cell reactivity marker demonstrated that the Schwann cells were more reactive during the regenerative process in the TPCLF group as compared to the TPCL group and the normal sciatic nerve. Altogether, the results of this study indicated that the implant of collagen with a supramolecular organization positively influenced and stimulated the regeneration process through the nerve gap, resulting in the formation of a better morphologically arranged tissue.

The Effect of Electrospun Gelatin Fibers Alignment on Schwann Cell and Axon Behavior and Organization in the Perspective of Artificial Nerve Design

“…Both collagen and gelatin have been used in the preparation of different internal filler in artificial nerve conduit manufacturing, among them hydrogels and fibers [ 2 , 27 , 28 , 29 , 30 , 31 ]. Collagen is included as a scaffold in polycaprolactone tubular prostheses, resulting in stimulation of nerve regeneration in the rat sciatic nerve model [ 32 ].…”

Optical birefringence changes in myelinated and unmyelinated nerves: A comparative study

“…As can be seen, there is no significant difference with the nerve orientation, except near the edge where the sample is thinner, confirming the strong light depolarization in the central part of the nerve. Moreover, contrary to experiments in very thin neural samples [26, 50–52], individual axons cannot be seen despite their strong birefringence because of a lack of contrast due to the averaging effect over many axons and to blurring from light scattering.…”

“…This can be explained by the more complex and inhomogeneous structure of these nerves. Nevertheless, thinner samples under a polarizing microscope have revealed that myelinated nerve axons are birefringent media [25,47,[50][51][52]. In particular, the myelin sheath, with its concentric layer structure, exhibits strong linear birefringence with a radially oriented optic axis.…”

Ultrastructural study of sciatic nerve in Ts1Cje mouse model for Down syndrome: an implication of peripheral nerve defects in hypotonia

“…The functional and structural index for assessing axonal myelination is the ratio of the axon diameter to the myelinated fibre diameter (g ratio) and the concept of g ratio has been used in assessing the degree of myelination of the peripheral nerves [19,20]. Recent studies have shown that, the g ratio concept is useful in evaluating the level of myelination of the sciatic nerve during aging [21].…”