Functional motor nerve regeneration without motor-sensory specificity following end-to-side neurorrhaphy: an experimental study

Challenges in Nerve Repair and Reconstruction

Peripheral nerve injuries may substantially impair a patient's function and quality of life. Despite appropriate treatment, outcomes often remain poor. Direct repair remains the standard of care when repair is possible without excessive tension. For larger nerve defects, nerve autografting is the gold standard. However, a considerable challenge is donor site morbidity. Processed nerve allografts and conduits are other options, but evidence supporting their use is limited to smaller nerves and shorter gaps. Nerve transfer is another technique that has seen increasing popularity. The future of care may include novel biologics and pharmacologic therapy to enhance regeneration.

Stem cells in end-to-side neurorrhaphy. Experimental study in rats

Purpose:

To evaluate the influence of mesenchymal stem cells from adipose tissue in the end-to-side neurorrhaphy, focusing in the nerve regeneration and the muscle reinnervation in acute trauma.

Methods:

140 animals were randomly divided in seven groups: control, denervated, end-to-side neurorrhaphy between distal stump of common peroneal nerve and tibial nerve (ESN), ESN wrapped in fascia, ESN wrapped in fascia and platelet gel, ESN wrapped in platelet gel, ESN wrapped in fascia and platelet gel within stem cells (without culture) removed from the adipose tissue. Mass measurements of the animal and of cranial tibial muscles, electromyography, walking track analysis tests and histological examinations of the nerves and muscles after 180 days was performed.

Results:

In the groups where the ESN was performed, the results were always better when compared to the denervated group, showing reinnervation in all ESN groups. The most sensitive methods were walking track and histological analysis. Only the group with stem cells showed values similar to the control group, as well as the functional indices of peroneal nerve and the number of nerve fibers in the peroneal nerve.

Conclusions:

Stem cells were effective in ESN according with the functional index of the peroneal nerve, evaluated by walking track analysis and the number of nerve fibers in the peroneal nerve.

End-to-side neurorrhaphy repairs peripheral nerve injury: sensory nerve induces motor nerve regeneration

End-to-side neurorrhaphy is an option in the treatment of the long segment defects of a nerve. It involves suturing the distal stump of the disconnected nerve (recipient nerve) to the side of the intimate adjacent nerve (donor nerve). However, the motor-sensory specificity after end-to-side neurorrhaphy remains unclear. This study sought to evaluate whether cutaneous sensory nerve regeneration induces motor nerves after end-to-side neurorrhaphy. Thirty rats were randomized into three groups: (1) end-to-side neurorrhaphy using the ulnar nerve (mixed sensory and motor) as the donor nerve and the cutaneous antebrachii medialis nerve as the recipient nerve; (2) the sham group: ulnar nerve and cutaneous antebrachii medialis nerve were just exposed; and (3) the transected nerve group: cutaneous antebrachii medialis nerve was transected and the stumps were turned over and tied. At 5 months, acetylcholinesterase staining results showed that 34% ± 16% of the myelinated axons were stained in the end-to-side group, and none of the myelinated axons were stained in either the sham or transected nerve groups. Retrograde fluorescent tracing of spinal motor neurons and dorsal root ganglion showed the proportion of motor neurons from the cutaneous antebrachii medialis nerve of the end-to-side group was 21% ± 5%. In contrast, no motor neurons from the cutaneous antebrachii medialis nerve of the sham group and transected nerve group were found in the spinal cord segment. These results confirmed that motor neuron regeneration occurred after cutaneous nerve end-to-side neurorrhaphy.

Peripheral nerve regeneration after experimental section in ovine radial and tibial nerves using synthetic nerve grafts, including expanded bone marrow mesenchymal cells: morphological and neurophysiological results

The standard treatment of peripherical nerve injuries with substance gap is to introduce the nerve free extremes in a biodegradable tube which, as a biocamera, allows the continuity of the nerve, promote the neuroconduction and save the lesion from the surrounding fibrosis. However, this procedure has not any direct effect on the neuroregeneration nor to resolve high severe lesions. The mesenchymal stem cells (MSC) can derivate "in vitro" in different lineages, including Schwann cells. Different studies have shown MSC can promote the nerve regeneration in rodents, dogs and primates. Moving to the human clinical application requires the procedure standardization, including the optimal cell dose which we have to use. In the sheep model animal we performed a study of 1 cm. nerve section-ressection and repair with a Neurolac™ biocamera, in whose gap we applied between 30 to 50×10(6) MSC from cancellous bone, all of them selected and cultured with GMP procedures. The results were compared with controls (saline serum ± platelet-rich plasma). We used radial nerve (sensitive) and tibial nerve (motor) from 7 sheep. In the first step we performed the surgical lesion and bone marrow aspiration, and in 3 weeks we performed the surgical repair. 3 sheep were sacrificed in 3 months, and 4 sheep in 6 months. In all surgeries we performed a neurophysiological register. When we obtained the tissue samples, we performed an histological, immunohistiquimical and morphometrical study. The recovery percentage was defined comparing the axonal density from the proximal and distal lesion margins. The 3 months samples results were wrong. In 6 months samples results we observed a significative myelined nervous fibers and conduction increasing, in front of controls, both radial and tibial nerves. These results suggest the MSC application in biodegradable scaffold in nerve injuries promotes good results in terms of regeneration and functional recovery.

Peripheral nerve repair and reconstruction

When possible, direct repair remains the current standard of care for the repair of peripheral nerve lacerations. In large nerve gaps, in which direct repair is not possible, grafting remains the most viable option. Nerve scaffolds include autologous conduits, artificial nonbioabsorbable conduits, and bioabsorbable conduits and are options for repair of digital nerve gaps that are <3 cm in length. Experimental studies suggest that the use of allografts may be an option for repairing larger sensory nerve gaps without associated donor-site morbidity.