1. Characterization of the Stiffness and Cytotoxicity of Poly(ethylene glycol) Diacrylate
Hydrogels for Retinal Tissue Engineering
Tyler DiStefano1, Corina White2, Dr. Ronke Olabisi2
1Department of Mechanical Engineering, The Cooper Union, New York, NY
2Department of Biomedical Engineering, Rutgers University, Piscataway, NJ
INTRODUCTION AND BACKGROUND
PEG-DA Hydrogels Prepared:
Ø 1X and 2X concentration 3.4kDa
Ø 1X and 2X concentration 5kDa
Ø 1X and 2X concentration 10kDa
Ø 1X and 2X concentration 20kDa
Ø 1X and 2X concentration 4-ARM
KEY FINDINGS
EXPERIMENTAL DESIGN
RESULTS AND DISCUSSION
• Dry Age-related Macular Degeneration (AMD) is
a condition that compromises visual function
due to its debilitating effects on mechanical and
transport properties within the blood-retinal
barrier.[1]
• Dry AMD occurs from the build up of carrier
lipoproteins that transport essential vitamins and
glycosaminoglycans (GAGs) to photoreceptors
across Bruch’s membrane.[1]
• No treatment exists for dry AMD, and is the
leading cause of blindness in developed
countries.[2]
• Clinical trials entail a localized injection in the
eye without a scaffold, which leads to cell
migration and low viability[3]
• Poly(ethylene glycol) diacrylate (PEG-DA) is
a seemingly attractive biocompatible
polymer, which is widely used in hydrogel
research applications.[4]
• Hydrogel composition corresponds to
characteristic material properties:
o Molecular weight and concentration of
PEG-DA affects Young’s Modulus
• BROADER GOAL OF RESEARCH:
Ø Understand if Young’s modulus of PEG-DA cultured hydrogels enhances co-
cultured stem cells differentiate into Retinal Pigment Epithelium (RPE) cells.
• SPECIFIC GOAL OF RESEARCH:
Ø Characterize Young’s modulus of different PEG-DA hydrogels and determine RPE
cell viability on cultured substrates.
PHASE II:
PHASE III:
CELL VIABILITY RESULTS
20kDa, 1X Concentration 10kDa, 2X Concentration
3.4kDa, 1X Concentration 5kDa, 2X Concentration
FIGURE 1 – Dry AMD within the
blood-retinal barrier.
Source: https://www.scienceofamd.org/wp-content/uploads/
2012/01/slide_5_resize.jpg
FIGURE 4 –Young’s modulus for double-network
PEG-DA hydrogels
FIGURE 7 – Day 1 cell viability in various environments
FIGURE 5 –Young’s modulus for surface
patterned PEG-DA hydrogels
FUTURE WORK
REFERENCES
ACKNOWLEDGEMENTS
• A very special thank you to Dr. Ronke Olabisi, Corina White, and the rest of the lab members for a warm
welcome into the Biomedical Engineering laboratory.
• Thank you to Dr. Evelyn Erenrich and Dr. David Shreiber of Rutgers University for their support and
acceptance into the RiSE/REU program.
• Thank you to the NSF for the organization and funding of the REU program in Cellular Bioengineering: From
Biomaterials to Stem Cells: NSF EEC 1262924.
• Increase the concentration of RGD within the PEG-DA hydrogels, and
examine if the higher concentration of RGD supports cell life on the
hydrogels on and after Day 7.
• Analyze stem cell differentiation into Retinal Pigment Epithelium (RPE)
cells on cultured substrates:
o Expose stem cells to a direct co-culture with RPE cells
o Expose stem cells to an indirect co-culture with PEG-DA
microencapsulated RPE cells
PHASE I:
• Chosen Hydrogel Scaffolds to seed ARPE-19 on:
Ø 20kDa PEG-DA, 1X concentration, EY = 60kPa
Ø 10kDa PEG-DA, 2X concentration, ~5EY = 280kPa
Ø 3.4kDa PEG-DA, 1X concentration, ~10EY = 500kPa
Ø 20kDa PEG-DA, 2X concentration, ~20EY = 1100kPa
Ø Tissue Culture Plastic (Control)
• Use 3mM RGD tripeptide (arginine-glycine-aspartic acid)
to attach ARPE-19 cells onto the hydrogel
• Live/Dead Stain at Days 1, 7, and 14 to determine cell
viability
MECHANICAL TESTING RESULTS
FIGURE 3 – Young’s modulus for single-network PEG-DA hydrogels
FIGURE 8 – Correlation between
Young’s modulus and ARPE-19 viability
Ø Correlation between Young’s
modulus and cell viability reveals
that an increased material
stiffness is more likely to
support RPE cell life
Ø Day 7 indicated no cell viability,
which was thought to be from too
low of an RGD concentration
within the hydrogel
• Single network PEG-DA hydrogels are on average three times more stiff when the chemical
concentration doubles.
• Double network PEG-DA hydrogels have a Young’s modulus that is approximately the sum of the
composing moduli.
• Topographical patterns do not have a statistically significant effect on the mechanical properties of
PEG-DA hydrogels.
• ARPE-19 cells are more viable on hydrogels with a stiffness similar to that of a healthy Bruch’s
membrane.
FIGURE 6 – Live/Dead stain of ARPE-19 cells
[1] Curcio, Christine. Johnson, Mark. “Structure, Function, and Pathology of Bruch’s Membrane” Anatomy and Physiology: Basic Science
and translation to Therapy (2013) 465-481
[2] National Institute of Health, National Eye Institute. Fact Sheet: Leading Causes of Blindness in the U.S. Web. 20 June 2014.
[3] Macular Degeneration Partnership. Dry AMD Clinical Trials. Web. 3 July 2014.
[4] Mazzoccoli, Jason. Feke, Donald. Baskaran, Harihara. Pintauro, Peter. “Mechanical and Cell Viability Properties of Crosslinked Low
and High Molecular Weight Poly(ethylene glycol) Diacrylate Blends.”Journal of Biomedical Materials Research. (2010) 558-566