Transcript Response of human mesenchymal stem cells to modified biomaterial surfaces Mura McCafferty

Response of human mesenchymal stem
cells to modified biomaterial surfaces
Mura McCafferty
Young Persons’ World Lecture Competition
Kuala Lumpur
September 2010
Tissue Engineering
Holds the promise of being able
to produce functional tissue
and organs for transplant
Skin
Trachea
Ear
Bladder
Stem Cells
Mesenchymal Stem Cells (MSCs)
• Can be sourced from the bone
marrow, peripheral blood,
adipose tissue, dental pulp
and synovium
• Can be easily isolated and
expanded in culture to
generate large numbers of
cells
• Multipotent - capable of
producing cells of different
lineages
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Mesenchymal Stem Cells
Bone Tissue Engineering
• Bone struggles to heal large
defects caused by:
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Disease
Non-union fracture
Age
Tumors
Congential Deformations
• Commonly used methods to aid
healing of large defects include:
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Intramedullary pins
Plating
Synamic external fixation
Bone grafts
MSCs and bone tissue engineering
Isolate MSCs
from patient
Expand MSCs
in vitro
+ Dexamethasone
+ L-ascorbic acid-2-phosphatase
+ β-glycerophosphate
Induce osteogenic
differentiation
• Expensive
• May cause adverse reaction to
Transplant cells
body
back to defect site
MSCs and bone tissue engineering
• There is therefore an existing need to develop
alternative methods of inducing the osteogenic
differentiation of MSCs
• One such route:
FUNCTIONAL BIOMATERIALS
Control of osteogenic differentiation
through modified biomaterials
• The chemical and physical properties of a biomaterial has a significant
effect on cell behaviour
• It is thought, and has been demonstrated in some studies, that surface
topographical features have the potential to induce osteogenic
differentiation of MSCs
– Dalby, M.J., et al., The control of human mesenchymal cell differentiation using
nanoscale symmetry and disorder. Nat Mater, 2007. 6(12): p. 997-1003.
– Sjostrom, T., et al., Fabrication of pillar-like titania nanostructures on titanium
and their interactions with human skeletal stem cells. Acta Biomater, 2009.
5(5): p. 1433-41.
– Bigi, A., et al., In vitro culture of mesenchymal cells onto nanocrystalline
hydroxyapatite-coated Ti13Nb13Zr alloy. J Biomed Mater Res A, 2007. 82(1): p.
213-21.
MSCs cultured on
planar PMMA
MSCs cultured on
embossed PMMA
Sputter Deposition
Previous published studies have shown that sputter deposited titanium (Ti) and
calcium phosphate (CaP) thin films can promote bone cell attachment and proliferation
Sputter deposition is a thin film coating process that has been used successfully to
provide bioactive layers that are inherently osteoconductive
Sputter deposited Ti and CaP thin films have promising potential for directing the
osteogenic differentiation of MSCs
CaP
Titanium
Substrate
500 nm
Substrates
Glass:
Amorphous glass substrate (control)
Ti:
Annealed (500°C) titanium coating on glass
TiCaP:
Annealed (500°C) calcium phosphate coating on Ti interlayer on
glass
Glass
Ti
AFM images showing 3D analysis of substrates
Surface Roughness
Sample
Average Ra (nm)
Glass
3 ± 0.5
Ti
17 ± 2
Ti/CaP
22 ± 2
Ti/CaP
MSCs cultured in osteogenic media
Alizarin Red Staining
DAY
DAY 28
14
21
7
NORMAL MEDIA
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OSTEOGENIC MEDIA
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Gene expression analysis - Collagen I
mRNA expression of Collagen I in MSCs cultured on control, Ti and Ti/CaP substrates
Gene expression analysis - Osteopontin
mRNA expression of Osteopontin in MSCs cultured on control, Ti and Ti/CaP substrates
Immunocytochemical Localisation of Osteopontin
Control
(Normal Media)
Control
(Osteogenic Media)
Ti
Ti/CaP
Summary
While MSCs hold great promise for use in bone tissue engineering
applications, there is a need for more effective in vitro expansion and
differentiation methods
– Reduce dependence on bone graft treatment
– Improve healing
– Reduce recovery time
CaP and Ti sputter deposited surfaces have utility in directing the osteogenic
differentiation of MSCs
While these are promising results and further research to fully understand if
this is as a result of the surface topography as supplied by the Ti coating or
by the potential bioactive nature of the CaP
Acknowledgements
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Professor Brian Meenan
Dr George Burke
Dr Peter O’Hare
Linzi Charters
Chris O’Kane
Dr Fiona McKavanagh