Medical Student Research Fellowship for Summer 2009

Mentor: Jonathan Cheng
Department: Plastic Surgery
Room number: F4.124
Mail Code: 8560
Phone number: 214-645-3178
E-mail: Jonathan.Cheng@UTSouthwestern.edu
Project title: Nerve Conduit Multiplier

Human subjects IRB approved project number (where applicable): NA

Animal subjects IRB approved project number (where applicable): 2008-0175

Project Type (patient-based research, animal-based research, or basic research; this characterization is only to permit a general classification for grouping similar types of projects)

Brief Description of Project:
Nerve grafts are the accepted reconstruction for "splicing" nerves that have missing segments. Expert clinicians have suggested that when insufficient nerve graft material exists, nerve grafts may be minced and placed into hollow conduits (tubes) in order to multiply the number of nerve defects which can be spanned by a finite amount of nerve graft. This principle is supported in studies by Mackinnon et al. which showed that "stepping stone" nerve slices may be placed within a hollow conduit in order to bridge longer nerve gaps.

In this study, rats will be employed, as they are the smallest animal species available in which nerve defects >3cm have been described. Nerve reconstructions will be performed using 5 different constructs: 4cm nerve grafts will serve as a positive control, as these are the current standard in nerve reconstruction. 4cm hollow conduits will serve as a negative control, as these are known to fail in nerve reconstruction beyond 3cm. 4cm conduits filled with 2.7cm (1:1.5 graft to defect ratio), 2cm (1:2 graft to defect ratio), and 1.7cm (1:3 graft to defect ratio) of nerve graft material which has been stripped of lining and minced will constitute the 3 experimental groups. These groups will test the ability to "multiply" the functional distance which may be reconstructed with a finite amount of nerve graft material. For example, if a single 4cm nerve graft can be successfully split into two 2cm segments and placed into two 4cm conduits, 4cm of nerve graft material will have effectively served to reconstruct 8cm of nerve defect.

Ten weeks after reconstruction, the nerves will be re-exposed under anesthesia and subjected to nerve conduction studies which are painless to the anesthetized animal. Following this, the nerves will be harvested for histologic evaluation and the animals sacrificed. Thus, the nerve conduction study and final nerve harvest will not be a survival procedure.
Previous Research Activities or Publications with Medical Students:

I have personally participated in summer research programs as a high school student, as a medical student and as a university student. I am very aware of the issues involved and the need for supervision, direction, and scientific focus. During my time in college, I supervised two high school students and two summer college students as the lead technician in a cell biology lab at Baylor College of Medicine. This will be my first experience with summer students at UT Southwestern, but it is a very exciting time for our lab.