3D Materials for Bioengineered Tissue Replacements Claire Dow1 supervised by Andrew Dove2, Department of Chemistry 1. MOAC DTC, Coventry House, University of Warwick, c.e.dow@warwick.ac.uk. 2. Department of Chemistry, University of Warwick, a.p.dove@warwick.ac.uk. 1. Intervertebral back disc degenera3on is a major cause of lower back pain
2. Engineering of a replacement 3ssue implant is the treatment goal Type I collagen forms ring structures Healthy 3ssue 7-­‐10 mm 4cm 3D Co-­‐ordinates of 3ssue implant Pa3ent MRI Scan Nucleus pulposus Anulus fibrosus 80% water hydrogel Z Stage Diseased 3ssue Synthe3c scaffold UV source Cell death UV Source 3D scaffold made by micro-­‐
stereo lithography (MSL) Loss of disc height and boundaries Gel dehydra3on Pa3ent stem cells graTed Pa3ent-­‐specific disc implant 3. Materials currently used in micro-­‐stereolithography are non-­‐degradable 4. Ketene acetals were blended adding degradable ester bonds to the materials Key scaffold proper3es: Ketene acetal synthesis 1. Tensile strength
2. Biocompa3ble
+ Hexa-­‐acrylate crosslinker 3. Degradable OH
O
pTSA
Cl
OH
+
OH
Poly(ethylene glycol) diacrylate (PEG D.A) Cl
O
+
O
OH
O
O
O
O
O
O
O
THF
-
O
+ HO
+ KCl
O
O
O
O
O
O
+ K+
n
O
O
O
Cl
O
O
Monomer blending percentage by volume O
O
O
O
Ketene acetal (%)
PEG D.A. (%)
Crosslinker (%)
0
5
10
15
20
80
75
70
65
60
20
20
20
20
20
UV 6. Basic hydrolysis revealed that the original material was in fact degradable 5. Tensile strength and biocompa3bility are retained Key scaffold proper3es: 1. Tensile strength
2. Biocompa3ble
O
3. Degradable O
O
O
Young's Modulus (MPa) UTS (MPa) Ul6mate Tensile Strength (UTS) 80 70 60 50 40 30 20 10 0 0 5 10 15 Ketene (% by volume) Young's Modulus H
H
900 800 700 C
600 500 C
n
400 H
300 200 100 C
O
0 20 0 5 10 15 Ketene (% by volume) 20 OH
Original material degrades to poly(acrylic acid) H
O
C
C HOHO
H
C
C
HO
OH
H
H
H
H
H
C
C
HC
HC
H
H
H HOH
CH
CH
C
C
H
H
H
H
Hydrolysis of the ketene blended polymer gives shorter poly(acrylic acid) chains Key scaffold proper3es: Control cells at 48 hours 2. Biocompa3ble
Cells at 48 hours with 20% ketene construct applied at 24 hours 3. Degradable Number of Cells (per well) 1. Tensile strength
Acknowledgements Many thanks to the Dove group, par3cularly Dr. Andrew Dove and Dr. Ian Barker, also to Dr. Simon Leigh and Marina Talib in the Department of Engineering, University of Warwick, and to Dr. Hamish Gilbert and Dr. Stephen Richardson in the School of Biomedicine, University of Manchester. Total Cell Count 140,000 120,000 100,000 80,000 Dead Cells Live Cells 60,000 Dead Live CCells ells 40,000 20,000 0 No construct 0 10 Ketene (% by volume) 20 References 1. Urban and Roberts (2003) Arthri3s Res Ther, 5:120-­‐130. 2. Adams et al., (2007) Biomechanics of Backpain, 2nd Edi3on. 3. Campagna et al., (2009) AJR Am J Roentgenol 192(4):987-­‐95. 4. Rohlmann et al., (2009) Eur Spine J. 18:89-­‐97.