Lab Location: AKH, Level 8, G2/02 and G3/12
Associated Clinical Department: Department of Surgery, Division of Plastic and Reconstructive Surgery
Laboratory Coordinator: Manzano-Szalai Krisztina Dr. MSc.
Tel: +43 1 40400 4710
Project 1: Identification of motor and sensory nerve target membrane proteins by phage display
Aidan Roche, Krisztina Manzano-Szalai
Recent advances in reconstructive surgical techniques have allowed improved control of prosthetic arms through targeted muscle re-innervation. This procedure relies on transferring residual nerves to intact nerves and muscle groups to amplify residual nerve activity, thus providing increased control of a customized, advanced prosthetic arm. However, this procedure is limited by the ability to accurately select and transfer nerves, and is performed by visual identification of nerves.
The aim of the current study is to identify specific molecules for motor and sensory nerves and use these proteins for specific peptide selection via phage display for nerve visualization.
Our primary target population is upper limb amputees needing improved control of prosthetic limbs. However, any patient suffering from peripheral nerve injury and needing surgical intervention will benefit from this approach. The technique will also aid in surgical planning, where protection of delicate nerves is essential, such as the safe excision of tumours that surround nerves. In addition, this technique would allow for monitoring of the state of peripheral nerves in patients with neuropathies related to diabetes or neurological insult. The technology would also act as a platform for application into other fields where targeted imaging of tissue is desirable.
Project 2: Reverse End To Side Neurorrhaphy
Introduction: Selective nerve transfers (SNT) are an important tool in extremity reconstruction. A relatively novel SNT-technique is the reverse end to side (RETS) neurorrhaphy. Evidence in the international literature is lacking.
Methods: In a rat model we will apply the RETS. In 4 groups different surgical modifications will be tested. Retrograde labeling, muscle function tests, and histomorphometry will be used for assessment.
1) Feasibility of RETS.
2) Pathohistological and neurobiological evaluation of the regenerative process.
3) How can nerve-regeneration be improved.
Project 3: Motor Unit Modulation
Introduction: Selective nerve transfers (SNT) are an important tool in extremity reconstruction. Little is known about the long-term effects on the muscle‘s motor unit.
Methods: In a rat model we will apply a SNT (ulnar nerve to caput longum bicipitis brachii). This will induce hyperinnervation of the muscle. Retrograde labeling, muscle function tests, and histomorphometry will be used for assessment.
Transfer of the Ulnar nerve (right) to the caput longum (left).
1) Effect of SNT on the motor unit.
2) The time frame of these changes.
3) Does it affect Motor unit recruitment (functionality)?
Project 4: A Quantitative Analysis of the Motor and Sensory Fibers of the Brachial Plexus in Man
Any surgical nerve reconstruction must take into account the topography and quantity of individual nerve fibers at any given level of injury.
To date, however, literature on qualitative and quantitative assessment of axons of the peripheral nerves of the upper extremity is scarce. Furthermore, these studies were based on a morpho-quantitative procedure. This histomorphometric approach, however, is unspecific due to overlapping caliber spectra of motor and sensory fibers. The aim of this study is to count the total number of motor fibers of the brachial plexus and its peripheral nerves using molecular characteristics to differentiate between motor and sensory fibers.
For that purpose we established an immunohistochemistry protocol for human peripheral nerves specimens. Nerve samples are harvested from organ donors immediately after death, fixed and cryoprotected. After visualization of motor and sensory fibers by immunohistochemistry quantification is performed using the microscopic tissue analyzing platform TissueFAXS from TissueGnostics. This system has unique software that automatically identify and analyze labeled structures on tissue sections.
Preliminary results indicate that the amount of motor fibers is lesser than originally thought. In particular, the percentage of motor nerve fibers to the total fiber number is dependent on the watched nerve.