Sustained bFGF-release tubes for peripheral nerve regeneration: comparison with autograft.

BACKGROUND: Despite numerous articles on the use of artificial nerve conduits, autologous nerve transplants remain the most effective for nerve repair. To improve this technique, the authors examined conduits containing gelatin hydrogel as a carrier enabling the sustained release of basic fibroblast growth factor (bFGF). METHODS: To confirm sustained bFGF release in vivo, nerve-guide tubes containing iodine-125-labeled bFGF with or without gelatin hydrogel were implanted under the skin of mice, and the remaining radioactivity was measured. Next, a 15-mm segment of the sciatic nerve was resected and repaired with autologous nerve (group 1), a tube with gelatin hydrogel and bFGF (group 2), a tube with bFGF alone (group 3), or a tube only (group 4). Histologic and functional analyses were performed for 16 weeks after surgery. RESULTS: The radioactivity from iodine-125-labeled bFGF incorporated into gelatin hydrogel decreased more slowly than iodine-125-labeled bFGF alone. Four weeks after surgery, significantly more regenerating axons were detected in group 2 than in groups 3 and 4, but the axonal density in group 2 was lower than in group 1. Similarly, the animals in group 2 showed significantly better motor performance than those in groups 3 and 4, but worse than those in group 1. The animals in groups 1 and 2 showed significantly better sensory recovery than those in groups 3 and 4. CONCLUSIONS: The nerve-guide tube containing gelatin hydrogel and bFGF promoted axonal regeneration after peripheral nerve injury, but not as well as autologous transplants. Understanding the limitations of this technique will facilitate its improvement for clinical applications.

Schwann-spheres derived from injured peripheral nerves in adult mice--their in vitro characterization and therapeutic potential.

Multipotent somatic stem cells have been identified in various adult tissues. However, the stem/progenitor cells of the peripheral nerves have been isolated only from fetal tissues. Here, we isolated Schwann-cell precursors/immature Schwann cells from the injured peripheral nerves of adult mice using a floating culture technique that we call "Schwann-spheres." The Schwann-spheres were derived from de-differentiated mature Schwann cells harvested 24 hours to 6 weeks after peripheral nerve injury. They had extensive self-renewal and differentiation capabilities. They strongly expressed the immature-Schwann-cell marker p75, and differentiated only into the Schwann-cell lineage. The spheres showed enhanced myelin formation and neurite growth compared to mature Schwann cells in vitro. Mature Schwann cells have been considered a promising candidate for cell-transplantation therapies to repair the damaged nervous system, whereas these "Schwann-spheres" would provide a more potential autologous cell source for such transplantation.

Duplicated thumb with enormous soft-tissue oedema - pacifier type of thumb duplication.

Here we presented the first case of pacifier type thumb duplication. A newborn Japanese girl with no family history had a duplicated thumb on her left hand. The duplicated thumb showed a very large, oedematous soft-tissue nubbin in its appearance and was resected on the fifth day after birth. X-ray showed hypoplastic phalanx bone, suggesting type II polydactyly. Histology of the resected thumb showed enormous oedema in its connective tissue with cartilaginous and neural elements. This case was quite similar to literary reported cases of pacifier polydactyly in post-axial polydactyly, and its pathological condition seemed to be distinctly different from floating type or rudimentary type thumb duplication. We considered this type of thumb duplication as pacifier type thumb duplication, rather than floating or rudimentary type, in order to understand its underlying pathophysiology and to avoid confusion in further discussions.

Optimizing the diameter of holes for flexible regeneration microelectrode.

In this study, we suggest a new guideline for regeneration microelectrode to be implanted between the severed stumps of peripheral nerves, the microelectrode designed particularly for connecting the signal line of an artificial hand directly to the nerve system. The nerve regeneration microelectrode is an interface device expected to realize a BMI (brain-machine interface).

Crossed over repair of the femoral sensory and motor branches influences N-CAM.

N-CAM, expressed by non-myelinating Schwann cells, was investigated by immunohistochemistry in transected rat femoral nerves, which were repaired either using a straight or a crossed over technique. N-CAM staining covered 30 and 11% of the cross-sectional area of sensory and motor branches, respectively, in uninjured nerves. After 3 days there was a transient smaller area of N-CAM staining following both the repairs. After a straight repair N-CAM area increased to the control values in both branches. In contrast, a crossed over repair resulted in a continuous increase of N-CAM in the motor branch, whereas the area in the sensory branch returned slowly to control values. N-CAM is influenced by an intentionally misdirected outgrowth of motor and sensory axons after nerve repair.

Compression of the lower trunk of the brachial plexus by a cervical rib in two adolescent girls: case reports and surgical treatment.

Presence of a cervical rib in children is extremely rare, particularly when symptoms of compression of the lower trunk of the brachial plexus occur. We present two cases with such a condition, where two young girls, 11 and 16 years of age were treated by resection of the cervical rib after a supraclavicular exploration of the lower trunk of the brachial plexus. The procedure led to successful results, objectively verified with tests in a work simulator, at one year follow-up.

Delayed nerve repair increases number of caspase 3 stained Schwann cells.

Caspase 3 staining in Schwann cells was investigated with immunohistochemistry, as a measure of Schwann cell apoptosis, after transection and immediate (day 0) or delayed rat sciatic nerve repair (30, 90 and 180 days post injury). Cleaved caspase 3 stained Schwann cells significantly increased at the site of lesion (SNL; median [IQR], 15.2 [7.0] %) and in the distal nerve segment (SND; 9.5 [3.6] %) 10 days after immediate repair. The number of cleaved caspase stained Schwann cells also increased significantly after delayed repair, irrespective of length of delay, at both locations (SNL: 22.0-27.1%; SND: 18.5-22.1%; p<0.05). Some cleaved caspase 3 stained satellite cells were seen in dorsal root ganglia on the injured side, but no stained motor or sensory neurons were observed at any time-point. Delayed nerve repair is associated with more pronounced Schwann cell apoptosis which may explain impaired nerve regeneration after nerve injury and delayed repair.

Expression of ATF3 and axonal outgrowth are impaired after delayed nerve repair.

BACKGROUND: A delay in surgical nerve repair results in impaired nerve function in humans, but mechanisms behind the weakened nerve regeneration are not known. Activating transcription factor 3 (ATF3) increases the intrinsic growth state of injured neurons early after injury, but the role of long-term changes and their relation to axonal outgrowth after a delayed nerve repair are not well understood. ATF3 expression was examined by immunohistochemistry in motor and sensory neurons and in Schwann cells in rat sciatic nerve and related to axonal outgrowth after transection and delayed nerve repair (repair 0, 30, 90 or 180 days post-injury). Expression of the neuronal cell adhesion molecule (NCAM), which is expressed in non-myelinating Schwann cells, was also examined. RESULTS: The number of neurons and Schwann cells expressing ATF3 declined and the length of axonal outgrowth was impaired if the repair was delayed. The decline was more rapid in motor neurons than in sensory neurons and Schwann cells. Regeneration distances over time correlated to number of ATF3 stained neurons and Schwann cells. Many neurofilament stained axons grew along ATF3 stained Schwann cells. If nerve repair was delayed the majority of Schwann cells in the distal nerve segment stained for NCAM. CONCLUSION: Delayed nerve repair impairs nerve regeneration and length of axonal outgrowth correlates to ATF3 expression in both neurons and Schwann cells. Mainly non-myelinating Schwann cells (NCAM stained) are present in distal nerve segments after delayed nerve repair. These data provide a neurobiological basis for the poor outcomes associated with delayed nerve repair. Nerve trunks should, if possible, be promptly repaired.

Specific expression of an HNK-1 carbohydrate epitope and NCAM on femoral nerve Schwann cells in mice.

Schwann cells are glial cells of the peripheral nervous system. There are two known subtypes of Schwann cells: those that are myelin-forming; and those that are non-myelin-forming. In this study, we looked at the expression of cell adhesion molecules in Schwann cells to determine whether other subtypes might exist. We used immunohistological analysis of femoral nerve segments containing sensory and motor fascicles, stained with anti-HNK-1, M6749 and anti-neural cell adhesion molecule (NCAM) monoclonal antibodies. Anti-HNK-1 and M6749 were positive in the motor fascicle, while anti-NCAM was positive in the sensory fascicle. Immunoblot analysis with the anti-HNK-1 and M6749 antibodies showed stronger immunoreactivity in the motor fraction than in the sensory fraction in the 100 kDa band. With the anti-NCAM antibody, the 140 and 120 kDa bands were seen in the sensory fascicle fraction, but not in the motor fascicle fraction. HNK-1-positive-cells were seen in motor fascicles 7 days after transection. However, the level of immunoreactivity diminished at 14 days, and no immunoreactivity was seen at 21 days. NCAM-positive cells were not observed 3 days after transection. In development, HNK-1-positive-cells and NCAM-positive cells were seen after P-21. These results suggest that the Schwann cells from the motor and the sensory fascicles have different subtypes. The motor and sensory Schwann cells may play different roles and function in a different way during peripheral nerve regeneration. In addition, there could be more stages of Schwann cell differentiation than previously thought; it is possible that myelin-forming Schwann cells differentiate into HNK-1-positive-cells (motor myelin-forming Schwann cells) and HNK-1-negative-cells (sensory myelin-forming Schwann cells), and non-myelin-forming Schwann cells differentiate into NCAM-positive cells (sensory non-myelin-forming Schwann cells) and NCAM-negative cells (autonomic non-myelin-forming Schwann cells).