Upload
alivingbandaid
View
469
Download
2
Embed Size (px)
DESCRIPTION
Thermally Reversible Gels for Tissue Engineering
Citation preview
March 8, 2013 Sigma Xi Competition
Hydrogel Composites with Carbon Nanobrushes for Tissue
Engineering
William H. Marks & Carolina I. Ragolta
Additional AuthorsSze C. Yang, George W. Dombi, & Sujata K. Bhatia
Medical Need: Cardiac Regeneration✤ Coronary Artery Disease
is a leading killer of men and women worldwide
✤ Congestive heart failure has 1-year mortality rate of 40%
✤ Image Source: National Heart Lung and Blood Institute
Medical Need: Cardiac Regeneration✤ Myocardial infarction
can lead to death of 109 cardiomyocytes
✤ 1.5 million Americans suffer myocardial infarctions each year
✤ Image Source: Medicine.net
Abstract
✤ Study carbon nanobrushes (CNBs) embedded in hydrogels for scaffolding in tissue engineering
✤ CNBs provide internal structure, conductivity, and are non-toxic
✤ Tested the ability of fibroblasts and myocytes to adhere to the gel and mechanical properties
✤ CNBs alter mechanical properties providing a high degree of customization
✤ Gels show promise for many wound healing applications
Medical Need: Regenerative Medicine
✤ Biomaterials must be biocompatible, non-cytotoxic, non-hemolytic, and non-inflammatory
✤ They must degrade within the physiologic environment
✤ Must be easily prepared, implantable, and scalable✤ Must be clinically relevant
Prior Related Work
✤ Cell encapsulation for 3D tissue growth (Hunt et al., 2010)✤ Collagen matrices for fibrogenesis (Chen et al., 2009)✤ Alginate gels with carbon nanotubes provide mild
inflammatory response (Kawaguchi et al., 2006)✤ “Scar in a Jar” collagen matrix for flexor tendon healing
(Dombi et al., 1994)✤ Cartilage tissue engineering by accurately spinning
hydrogels (Coburn et al., 2011)
Clinically Relevant Cell Lines
Primary Cardiac FibroblastsSource: Dr. Andrew Pelling, UCL
Primary Cardiac MyocytesSource: Dr. Poling Kuo, Harvard
Carbon Nanobrushes
✤ Electrically conducting polymers grafted onto carbon nanotubes
✤ Conductivity of materials is about 0.1 S/cm
✤ 5-20µm in length✤ 13-30nm in diameter✤ Imaged by negatively
staining with phosphotungstate
Pluronic F-127 Poloxamer Hydrogels✤ Reverse phase-change properties: solid at 37 , liquid at ℃
room temperature✤ Triblock copolymer of PEO-PPO✤ Non-ionic and biocompatible
Preparation of Composite Hydrogels with Carbon Nanobrushes✤ 30wt% poloxamer solution✤ Various CNB
concentrations✤ 0vol%✤ 0.1vol%✤ 0.5vol%✤ 1vol%
✤ Solidified at 37 and then ℃seeded with cells and DMEM
Growth of Fibroblasts
Fibroblasts in top layer of poloxamer gel after 48 hours
Migration of Fibroblasts
Fibroblasts in middle layer of poloxamer gel after 48 hours
Fibroblasts in bottom layer of poloxamer gel after 48 hours
Growth of Myocytes
Myocytes in top layer of poloxamer gel after 48 hours
Rheology: Temperature Sweep
Temperature sweep test of gels containing 0vol% and 5vol% CNB
Rheology: Time Sweep
Time sweep test of gels containing 0vol% and 5vol% CNB at 37℃
Rheology: Frequency Sweep
Frequency sweep test of gels containing 0vol% and 5vol% CNB at 37 ℃showing a crossover from predominately elastic to predominately viscous
Discussion
✤ Hydrogels embedded with CNBs support cell growth and migration
✤ CNBs change the properties of the gel on a macro scale by altering the frequency of the sol-gel transition point✤ Gels transition from predominately elastic to
predominately viscous✤ Additional degree of customizability
Ongoing and Future Work
✤ Properties of gels with different wt% of poloxamer✤ Incorporating crosslinkers into hydrogels✤ Injectability✤ Experiments with additional cell lineages
Translational Potential
Tissue PatchesSource: Gore
Skin GraftsSource: Medline
Tissue ScaffoldSource: National
Institute of Standards and Technology
Acknowledgements
✤ Dr. Sujata K. Bhatia, SEAS, Harvard
✤ Dr. Sze C. Yang, University of Rhode Island
✤ Dr. George W. Dombi, University of Rhode Island
✤ Dr. Patrick Campbell, SEAS, Harvard (Disease Biophysics Group)
✤ Harvard School of Engineering and Applied Sciences