John Stella

Faculty Mentor: Michael Sacks

Update: Dr. John Stella is currently working as a Product Specialist for W.L. Gore & Associates.

Research:Although current heart valve replacements have extended the lives of many patients, there is to date still no ideal alternative. Pediatric applications, in particular, pose unique problems because current valve replacement options are unable to grow and remodel with the patient. Tissue engineering aims to combine engineering and life science principles to overcome these current limitations by recapitulating native tissue structure, composition, and mechanical function in a controlled and reproducible manner. Before fully functioning tissue surrogates can be developed for clinical use, many complex biological, chemical and mechanical aspects of native tissues must be addressed. These complex and often interrelated characteristics are further confounded by complex hierarchical structures, vasculature, and multiple cell types. It is our focus to elucidate the effects of mechanical stimuli on the development of tissue engineered leaflet tissues. With our ability to incorporate viable cells distributed throughout the scaffold via concurrent electrospraying and electrospinning of poly (ester urethane) urea (PEUU) fiber scaffolds, we are provided a unique, controllable platform to: (1) characterize the mechanical behavior of electrospun PEUU and cellular response to global deformation, (2) assess our ability to create functional cell integrated surrogates via dynamic culture, and (3) develop a mathematical framework incorporating the coupled cell-matrix deformation behavior with the goal of predicting de-novo tissue formation and its contribution to tissue level mechanical behavior in response to dynamic mechanical stimuli. We contend that much can be learned about the mechanical modulation of functional tissue from electrospun PEUU scaffolds since they capture aspects of native tissue microstructure and exhibit the ability to endure large deformations while recovering completely. 

Publications:

• DAmore A, Stella JA, Wagner WR, Sacks MS. "Characterization of the complete fiber network topology of planar fibrous tissues and scaffolds". Biomaterials2010( ): , 2010 
• Stella JA, Sacks MS. "On the biaxial mechanical properties of the layers of the aortic valve leaflet". J Biomech Eng129(5)(757-66): , 2007 
• Stella JA, Liao J, Sacks MS. "Time-dependent biaxial mechanical behavior of the aortic heart valve leaflet". J. Biomech40(14)(3169-77): , 2007 
• Stella JA, Liao J, Hong Y, Merryman WD, Wagner WR, Sacks MS. "Tissue-to-cellular level deformation coupling in cell micro-integrated elastomeric scaffolds". Biomaterials29(22)(3228-36): , 2008 
• Stella JA, Wagner WR, Sacks MS. "Scale-dependent fiber kinematics of electrospun elastomeric scaffolds for soft tissue engineering". J Biomed Mater Res A2009( ): , 2009 
• Stella JA, Wagner WR, and Sacks MS. "On the mechanical function of scaffolds for engineering load-bearing soft tissues". Acta Biomater2010( ): , 201