Intraneural IFG-1 in Cryopreserved Nerve Isografts Increase Neural Regeneration and Functional Recovery in the Rat Sciatic Nerve

BACKGROUND

Insulin-like growth factor 1 (IGF-1) was found to stimulate Schwann cell mitosis. Exogenous IGF-1 may improve nerve regeneration after cryopreservation.

OBJECTIVE

To evaulate the effect of intraneural administration of IGF-1 in cryopreserved nerve isografts.

METHODS

Eighteen millimeter grafts were used for bridging an 18-mm defect in the rat sciatic nerve. A total of 57 rats were randomly divided into three groups: (1) autograft (Group 1); (2) cryopreserved isograft (Group 2); (3) cryopreserved isograft with intraneural IGF-1 administration (Group 3). 12 weeks after surgery, functional recovery (Sciatic functional index [SFI], Swing speed [SS], nerve conduction velocity [NCV], amplitude of compound motor action potentials [CMAP], and gastrocnemius muscle index [GMI]) and nerve regeneration (myelin sheath area, total fiber counts, fiber density, and fiber width) were all evaluated.

RESULTS

The intraneural injection of IGF-1 significantly improved SFI and SS at weeks 10 and 12. There were no statistical differences between Groups 1 and 3 in any of the SFI or SS evaluations. CMAP and NCV in Group 1 were significantly higher than in Groups 2 and 3, and Group 3 had significantly higher CMAP and NCV compared to Group 2. No significant differences were found in fiber width. The number of nerve fibers, percentage of myelinated fibers, fiber density, and GMI was significantly higher in Group 1 compared to Group 2, but no significant differences were found between Groups 1 and 3.

CONCLUSION

The results show that intraneural injection of IGF-1 in an 18 mm cryopreserved isograft improve axonal regeneration and functional recovery.

Capitolunate Arthrodesis versus Four-corner Arthrodesis in Scaphoin Nonunion Advanced Collapsed Wrist Treatment

Objective To evaluate the outcomes of scaphoidectomy and capitolunate arthrodesis versus four-corner arthrodesis in patients with stage III scaphoid nonunion advanced collapse (SNAC) wrists.

Methods We reviewed retrospectively all of the consecutive patients surgically treated in our center between 2007 and 2015, including 20 patients in the four-corner arthrodesis group and 11 patients in the capitolunate group. The mean follow-up time was of 47 months. The follow-up evaluation included wrist range of motion (ROM), grip strength, visual analogue scale (VAS), the disabilities of the arm, shoulder, and hand (DASH) questionnaire, and the Mayo wrist scale (MWS). Postoperative complications and the radiographic evaluation were also assessed.

Results There was no statistical difference in flexion, radial deviation, ulnar deviation, grip strength, VAS, DASH or MWS scores. There was a statistically significant increase (6°) in extension in capitolunate arthrodesis versus four-corner arthrodesis, possibly without clinical relevance. There were two nonunions in the four-corner group, and none in the capitolunate group. None of the patients in the capitolunate group required screw removal. One patient in the four-corner group required dorsal plate removal. One patient in each group required conversion to total arthrodesis.

Conclusions Capitolunate arthrodesis shows similar results in wrist ROM, grip strength and patient-reported outcomes when compared with four-corner arthrodesis at an average follow-up period of 4 years. We did not have any pisotriquetral arthritis in the capitolunate arthrodesis group, despite not removing the triquetrum in any of patients of this group.

Type of study/level of evidence Therapeutic III.

The addition of albumin improves Schwann cells viability in nerve cryopreservation

The purpose of the current study was to establish a valid protocol for nerve cryopreservation, and to evaluate if the addition of albumin supposed any advantage in the procedure. We compared a traditional cryopreservation method that uses dimethyl sulfoxide (DMSO) as cryoprotectant, to an alternative method that uses DMSO and albumin. Six Wistar Lewis rats were used to obtain twelve 20 mm fragments of sciatic nerve. In the first group, six fragments were cryopreserved in 199 media with 10% DMSO, with a temperature decreasing rate of 1 °C per minute. In the second group, six fragments were cryopreserved adding 4% human albumin. The unfreezing process consisted of sequential washings with saline in the first group, and saline and 20% albumin in the second group at 37 °C until the crioprotectant was removed. Structural evaluation was performed through histological analysis and electronic microscopy. The viability was assessed with the calcein-AM (CAM) and 4',6-diamino-2-fenilindol (DAPI) staining. Histological results showed a correct preservation of peripheral nerve architecture and no significant differences were found between the two groups. However, Schwann cells viability showed in the CAM-DAPI staining was significantly superior in the albumin group. The viability of Schwann cells was significantly increased when albumin was added to the nerve cryopreservation protocol. However, no significant structural differences were found between groups. Further studies need to be performed to assess the cryopreserved nerve functionality using this new method.