1. Young Persons’ World Lecture Competition
Response of human mesenchymal stem cells to modified biomaterial surfaces
Mura McCafferty
Young Persons’ World Lecture Competition
Kuala Lumpur
September 2010

2. Tissue Engineering
Holds the promise of being able to produce functional tissue and organs for transplant
Skin
Trachea
Bladder
Ear

3. Stem Cells

4. 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
Magnification 40X

5. Mesenchymal Stem Cells

6. Bone Tissue Engineering
Bone struggles to heal large defects caused by:
Disease
Non-union fracture
Age
Tumors
Congential Deformations
Commonly used methods to aid healing of large defects include:
Intramedullary pins
Plating
Synamic external fixation
Bone grafts

7. MSCs and bone tissue engineering
Dexamethasone
L-ascorbic acid-2-phosphatase
β-glycerophosphate
Expensive
May cause adverse reaction to body
Expand MSCs in vitro
Isolate MSCs from patient
Induce osteogenic differentiation
Transplant cells back to defect site

8. 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

9. 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, (12): p
Sjostrom, T., et al., Fabrication of pillar-like titania nanostructures on titanium and their interactions with human skeletal stem cells. Acta Biomater, (5): p
Bigi, A., et al., In vitro culture of mesenchymal cells onto nanocrystalline hydroxyapatite-coated Ti13Nb13Zr alloy. J Biomed Mater Res A, (1): p
MSCs cultured on planar PMMA
MSCs cultured on embossed PMMA

10. 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
500 nm
CaP
Titanium
Substrate

11. AFM images showing 3D analysis of 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
Ti/CaP
AFM images showing 3D analysis of substrates
Surface Roughness
Sample
Average Ra (nm)
Glass
3 ± 0.5 Ti
17 ± 2
Ti/CaP
22 ± 2

12. MSCs cultured in osteogenic media
Alizarin Red Staining
DAY 28
DAY 14
DAY 21
DAY 7
NORMAL MEDIA
Magnification 40x
OSTEOGENIC MEDIA
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13. Gene expression analysis - Collagen I
mRNA expression of Collagen I in MSCs cultured on control, Ti and Ti/CaP substrates

14. Gene expression analysis - Osteopontin
mRNA expression of Osteopontin in MSCs cultured on control, Ti and Ti/CaP substrates

15. Immunocytochemical Localisation of Osteopontin
Control
(Normal Media)
Control
(Osteogenic Media) Ti
Ti/CaP

16. 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

17. Acknowledgements Professor Brian Meenan Dr George Burke
Dr Peter O’Hare
Linzi Charters
Chris O’Kane
Dr Fiona McKavanagh