Neural Tissue Engineering: a Self Organizing Collagen Guidance Conduit

This paper discusses a new method of creating 3-D neural tissue using seeded collagen gels for self-alignment of the tissue. Within the medical community, nerve autografts are the "gold standard," but with the development of this nerve tissue method there is a potential for surgical implantation without removal of other nerve cells that damage donating nerves. Previous studies have shown that collagen gels are an effective way of attaining 3-D tissue cultures, therefore the researchers are applying this knowledge to create nerve cultures that have aligned schwann cells to match true nerve abilities both physically and biologically.

This research used collagen gels (rectangular)seeded with 25,000 schwann cells (prepared from male Fischer rats) per gel. Then dorsal root ganglia (taken from Sprague adult rats') were prepared using DMEM with collagenase. They were later applied to the collagen gels for adherence and growth.

After a 3 day incubation, the gels were washed, and stained with paraformaldehyde to detect betaIII-tubulin, a marker for neurons. Antibodies followed by secondary antibody allowed observation with fluorescence microscope.

The contruction of a device to mimic a nerve began with a silicone tube with eight holes for the collagen seeded gels to be pushed through (like a push pop). This device was inserted into female rat precisely damaged sciatic nerve for in vivo growth studies. If the inserted collagen moved away from the walls of the silicone tube, then self alignment would be considered successful.

The quantification of realignment and growth were performed using transverse and longitudinal sections taken from the insertion site along with the use of fluorescence microscopy.

The results reported showed that the schwann cells within the collagen gell had become aligned with the axis of the tube and DRG neurons extended paralled to the tube walls.

Evaluation of regeneration of a transverse section using the "collagenated tube", no inserted device and empty silicone tube showed that the collagenated had the greatest repairing abilities over time with the most growth.

Longitudinal sections showed the same results with most observed regeneration in the collagenated tubes.

Factors that may influenced results may include variation between rat species, age and sex. The age of the source of DRG may have influeced the potential for regrowth. The change from male to female for the in vivo test may also have affected the amount of regeneration and the direction of the alignment.

This paper presents a good protocal for the development of neural tissue to have correct alignment, essential for nerve communication. This paper was interesting especially after reading previous posts about tissue regeneration. Protocols for tissue development used collagen gels and this further exemplified the potential for 3-D culture. This paper caught my attention because of its attention to detail of the protocol and the future application of this device for treatment of patients with nerve damage such as from car accidents or war injuries.