Harnessing the Power of Apoptosis to Create Regenerative Acellular Biologic Scaffolds

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1605223 - SchmidtMany successes in regenerative medicine have been achieved through the use of naturally derived materials and particularly decellularized matrices, e.g., decellurized human dermis and decellurized human nerve graft. One key limitation to further advancement of these decellularized matrices is a loss of matrix microarchitecture and bioactivity during standard decellularization processing, which often starts with a process to induce cell necrosis (death through damage), releasing intracellular components throughout the matrix, followed by washes using harsh chemicals to remove cell remnants, which also results in undesired matrix destruction and removal of favorable bioactive factors. This project seeks to shift the paradigm in decellularization techniques by inducing apoptosis (programmed cell death) rather than necrosis. During apoptosis cells detach from the matrix and form small apoptotic bodies containing cellular components that can be readily removed. Furthermore, during apoptosis cells secrete cytokines that are known to aid in tissue regeneration in the remaining extracellular matrix. The apoptosis technique will be used to develop nerve and lung tissue specific matrices with preserved microarchitecture and bioactive factors that can be compared to commercially available products. The nerve tissue matrix will be tested in a rat sciatic nerve defect model, also in comparison with commercially available products. Results obtained are expected to contribute to the medical research community by creating a new platform for generation of acellular tissue specific matrices with enhanced regenerative potential, which could dramatically shift the future of regenerative medicine. Educational and outreach impact will be achieved through training of a graduate student and several undergraduate students and developing fun interactive lessons and labs to teach middle school students about biomaterials and biomedical engineering and to increase young women's interest in STEM.The goal of this project is to harness the power of apoptosis induced cell death to create tissue specific matrices with preserved microarchitecture and bioactive factors capable of enhancing regeneration in tissues and organs. Naturally derived materials and particularly decellularized matrices have been essential to success in regenerative medicine. One key limitation to further advancement of these decellularized matrices is a loss of fine matrix structure and bioactivity during standard decellularization processing. The hypothesis of this work is that induction of cell death by apoptosis will enable easier and gentler cell and antigen removal, thus better preserving matrix microarchitecture and bioactive factors. Furthermore, apoptotic cells secrete factors to enhance regeneration after implantation. Biological scaffolds derived from tissue specific extracellular matrix are highly desirable for tissue engineering and regenerative medicine because they are composed of proteins native to the implant site and provide a scaffold for regeneration. However, it is important to remove all cellular components prior to implantation to prevent immunogenicity. Most commonly used commercial decellularization start with a process to induce cell necrosis, releasing intracellular components throughout the matrix, followed by washes using harsh chemicals to remove cell remnants, which also results in undesired matrix destruction and removal of favorable bioactive factors. This project seeks to shift the paradigm in decellularization techniques by inducing apoptosis rather than necrosis. During apoptosis cells detach from the matrix and form small apoptotic bodies containing cellular components, which can be readily removed. In addition, during apoptosis cells secrete cytokines that can be sequestered in the ECM, and are known to induce proliferation, stem cell recruitment, and immunomodulation, thereby aiding in tissue regeneration. In Specific Aim 1 exploits cell apoptosis in representative tissues and organs (nerve and lung) to create novel tissue specific matrices with preserved microarchitecture and bioactive factors. Bioactivity and regenerative potential of apoptosis-optimized acellular grafts will be compared to grafts from a commercially used decellularization technique. Specific Aim 2 uses in vivo models to analyze immune response and regenerative potential of apoptosis-optimized acellular grafts versus grafts created from a commercially used decellularization technique. Results obtained are expected to contribute to the medical research community by creating a new platform for generation of acellular tissue specific matrices with enhanced regenerative potential, which could dramatically shift the future of regenerative medicine. Educational and outreach impact will be achieved through training of a graduate student and several undergraduate students, developing fun interactive lessons and labs to teach middle school students about biomaterials and biomedical engineering, developing lessons for 6th-8th grade girls at Girl?s Place, Inc. to increase young women?s interest in STEM and forging a new collaboration with the Cade Museum of Gainesville to expand lessons into full scale labs that will be run regularly to encourage creativity and invention in children.