a new healthcare technology
Department of Materials, University of Oxford
Parks Road, Oxford, OX1 3PH, UK
• Biomaterials science may be the most
multidisciplinary of all the sciences which
encompasses aspects of medicine, biology,
chemistry, engineering and materials science.
• Biomaterials are : “Non-viable materials used in a
medical devices intended to interact with
biological systems” [D.F. Williams, 1987]
• Joint replacements
• Bone plates
• Bone cement
• Hip Joint
• Artificial ligaments and
• Dental implants for tooth Heart valve Hip joint
• Blood vessel prostheses
• Heart valves
• Skin repair devices
• Cochlear replacements
• Contact lenses
Knee joint Skin
Biomaterials at Oxford
Drug Delivery Systems characterization
In vitro Testing
Tissue Engineering Cell culture
Human Tissue Damage
• Disease (e.g cancer, infection).
• Trauma (e.g accidental, surgery).
• Congenital abnormalities (e.g birth defects).
• Current clinical treatment based on:
Grafts and Transplants
• High cost : $400B in USA each year
US: 1July 2001- 30 June 2002
Organ No. patients on No. patients No. Patients died Cost per
waiting list received waiting operation in 1987
Lung 3 757 1 071 463 -
Heart 4 097 2 155 589 $ 110 000
Kidney 50 240 14 385 3 052 $ 30 000
Liver 17 379 5 261 1 861 $ 238 000
Pancreas 1 151 541 28 $ 40 000
[Cooper .T (1987): Human Organ Transplantation: Societal, medical-legal, regulatory, and Reimbursement
Issues ed. Cowen D.H et al, Health Administration Press Ann Arbor, MI, pp. 19-26]
Example: Bone Fractures in UK
• Bone is second transplanted tissue after blood.
• Healthcare in the United Kingdom alone set to
cost over 900£ million each year.
• Each year in the UK: 150,000 fractures due to
• Hip fracture is associated with high morbidity and
• 30-50% of these hip operations with require
subsequent revision surgery.
Total Hip Joint Replacement
• 50,000 hip replacements (arthroplasties) in Britain each year.
• Hydroxyapatite porous coatings in orthopaedic prostheses: Bioactivity, Osteoconductivity.
• Problem: Infections in orthopedic surgery (10% of cases)
• Prostheses have significantly improved the
quality of life for many ( Joint replacement,
Cartilage meniscal repair, Large diameter
blood vessels, dental)
• However, incompatibility due to elastic
mismatch leads to biomaterials failure.
• Tissue loss as a result of injury or disease,
in an increasing ageing population, provide
reduced quality of life for many at
significant socioeconomic cost.
• Thus a shift is needed from tissue
replacement to tissue regeneration by
stimulation the body’s natural regenerative
• National Science Foundation first defined tissue
engineering in 1987 as “ an interdisciplinary
field that applies the principles of engineering
and the life sciences towards the development
of biological substitutes that restore,
maintain or improve tissue function”
• Potential advantages:
– unlimited supply
– no rejection issues
Human Cell Nutrients,
Suspension Scaffold Growth
• A 3D substrate that is key
component of tissue engineering
• It needs to fulfil a number of
- Controllably Porous structure
- Interconnecting porosity
- Appropriate surface chemistry
- Appropriate mechanical
- Biodegradable material
• Synthetic polymers:
Aliphatic polyesters such as polyglycolic acid (PGA),
polylactic acid ( PLLA), copolymers ( PLGA) and
polycaprolactone ( PCL) are commonly used in tissue
• Natural polymers:
Most popular natural polymer used in tissue
engineering is collagen.
• More controllable from a compositional and
materials processing viewpoint.
• Scaffold architecture are widely recognized as
important parameters when designing a scaffold
• They may not be recognized by cells due to the
absence of biological signals.
• Natural materials are readily recognized by cells.
• Interactions between cells and biological ECM are
catalysts to many critical functions in tissues
• These materials have poor mechanical properties.
Chen and Mooney Pharmaceutical Research, Vol. 20, No. 8, August 2003.
[3H] thymidine uptake of chondrocytes
Cumulative TGF-β1 release from encapsulated in collagen/chitosan/GAG
chitosan microspheres. scaffolds with and without TGF-β1
J.E. Lee et al. / Biomaterials 25 (2004) 4163–4173
Oxford Biomaterials group
• Rapid prototyping:
3D wax printer
• It is the ideal scaffold material:
is an important ECM molecule and is the major
structural component in the body.
posses ideal surface for cell attachment in the body.
biocompatible and degrades into harmless products
that are metabolized or excreted.
a very poor antigen , non-toxic.
• This technique allow
the control over pore
size and porosity.
• Achieved through
variation of freezing
Dry collagen scaffold concentration
Indirect Solid Freeform fabrication
Computer Aided Design
1 2 Jet Head Dissolve away Negative
AutoCAD design Negative mould fabrication process
Scaffold Critical Point Drying Removal of BioBuild
at -30°C casting
Collagen scaffold fabrication
From Dr. Chaozong Liu Printing video
Tissue engineering scaffold: controlled architecture
Pre-defined channels; with
highly porous structured matrix;
With suitable chemistry for
tissue growth – Collagen or HA
No toxic solvent involved, it
offers a strong potential to
integrate cells/growth factors
with the scaffold fabrication
From Dr. Terry Socholas
Advantages of ISFF
• Control of the external structure:
Heart valve tissue engineering
Valve cells Collagen scaffold Heart valve post-
of heart valve implantation
Scaffolds with microchannels
Aclian Blue staining revealed that
extensive chondrogenesis were produced
along the channels. Sirius Red staining
revealed collagens production
( osteogenesis) in the periphery.
SEM images of scaffolds with hMSCs seeded channelled collagen scaffold
channels and open porosity. stained with Sirius Red and Alcian Blue
Take home message
• Biomaterials are materials interact with biological
• It’s a multi-disciplinary subject
• Important application include
– efficient drug delivery in the body
– Development of artificial tissue replacement similar to
the original for clinical use
– By tracking elemental fluctuation archaeology
information can be revealed