Topic Overview:
Each year in the U.S., growing numbers of patients sustain vital nerve and soft tissue injury due to trauma, tumors, infection, or surgery. Regenerative medicine works to accelerate the healing process and regrow missing or damaged tissue. The use of human stem cells is revolutionizing this field, demonstrating in vitro and in vivo an immense potential for growth and plasticity.

Dr. Marra’s research focuses on cultivating adult stem cells and developing biomaterials and drug delivery applications to promote nerve and soft tissue regeneration after injury. Current methods to repair peripheral nerve lesions are limited to axon lengths of less than 3 cm. In order to spur so-called “long gap” nerve regeneration and reinnervate distal muscle, Dr. Marra takes an innovative two-pronged approach using a rat sciatic nerve defect model.  The first step is the implantation of adult adipose derived stem cells (ASCs) within biodegradable nerve guides.  The second is the long-term controlled release of neurotrophic factors from within double-walled polymer microspheres embedded in the nerve guide wall. The results of her work are promising, demonstrating repopulation of muscle cells and increased myelination in the regenerated and distal nerve.

Soft tissue repair following procedures like tumor removal or mastectomy is the other major focus of the Marra lab. Here again, stem cells play a breakthrough role. Traditional therapies utilizing fat cell injections to replace soft tissue are hampered by central mass necrosis and fat resorption over time. By encapsulating ASCs within an injectable hydrogel scaffold, Dr. Marra showed that the ASCs not only survived the gelation process but also regenerated fat tissue on the matrix. Further, in a mouse model, the use of polymer microspheres to deliver growth factors was shown to enhance ASC vascularization and viability and to support soft tissue regrowth.