Jonathan Repper

Jonathan Repper
Mentor: Dr. Byron Petersen
College of Engineering
"I applied to USP to prepare myself for graduate school and to gain more hands on lab experience. I believe the research our group is involved with is interesting and has the potential to make a huge impact on the field of regenerative medicine."


Materials Science and Engineering



Research Interests

  • Tissue Engineering
  • Biomaterials
  • Hydrogels

Academic Awards

  • Anderson Scholar Award
  • President's Honor Roll
  • Hobe and Gertrude Hooser Scholarship
  • F.N. Rhines and W.R. Tarr Scholarship


  • Tau Beta Pi
  • Golden Key International Honor Society
  • Society for Biomaterials


  • GatorTRAX
  • March for Babies
  • E-week

Hobbies and Interests

  • Technology
  • Painting

Research Description

Effect of Decellularized Liver Matrix Stiffness on Hepatic Tissue Regeneration
Liver disease affects millions of patients each year. The field of regenerative medicine promises alternative therapeutic approaches, including the potential to bioengineer replacement hepatic tissue. One approach combines cells with acellular scaffolds derived from animal tissue. The success of whole organ regeneration relies on a multitude of variables including substrate mechanical properties. Normal liver has been shown to have an elastic modulus of 300 to 600 Pascal (Pa), increasing to 20 kPa or higher as fibrosis and cirrhosis develop. Compared with tissue culture plastic or glass, which are in the gigapascal range, the current culture and study techniques of hepatic cells are in highly non-physiologic mechanical environments (Wells 2008). Utilizing a rat liver decellularization technique similar to our own (Shupe, Williams et al. 2010), a previous group measured the magnitude difference in modulus between perfused native and decellularized livers (Evans, Moran et al. 2012). The altered substrate properties affect cell attachment, proliferation, and function during recellularization (Discher, Janmey et al. 2005). We hypothesize our current decellularized liver matrices are not stiff enough for optimal hepatic tissue regeneration and propose treatment with collagen cross-linking reagents to increase hepatic tissue regeneration. Decellularized scaffold biopsies will be treated with glutaraldehyde, ethanol, or lyophilization to increase stiffness of the scaffolding material. Sample elastic moduli will be determined by atomic force spectroscopy and microindendation. Once characterized, samples will be seeded with HepG2 and/or HUVEC cells as representatives for hepatocyte and endothelial cell populations essential for whole liver regeneration. The attachment, proliferation, and function of the cells will be evaluated histologically up to seven days. The results of this project will optimize our group’s protocols for whole hepatic scaffold regeneration.