Tissue Engineering: a new healthcare
technology
Biomaterials
• 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]
Biomaterials: Examples• Joint replacements • Bone plates • Bone cement • Hip Joint• Artificial ligaments and
tendons • Dental implants for
tooth fixation • Blood vessel prostheses • Heart valves • Skin repair devices • Cochlear replacements • Contact lenses
Hip jointHeart valve
Knee joint Skin
Biomaterials at Oxford
Nano-SIMS characterization
of TeethDrug Delivery Systems
Biomaterials Group Materials Dept.
In vitro TestingCell culture
Tissue expanderTissue Engineering
• 3-D scaffolds for tissue engineering
Example - Total Hip Replacement
Computer Graphic Actual femur head removed
Osteoarthritis
Some Artificial Hips
• UHMWPE
• Alumina
• Ti 6Al4V, Co-Cr, 316L stainless steel
Implants – An X-Ray View
New After 10 years
Gap
Bone is resorbed when not stressed.
A gap forms around the blade of the insert.
• 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)
Total Hip Joint Replacement
Bioreactorsystem
Scaffold
Biopsy
mechanical stimuli
electrical stimuli
chemical stimuli
Human Cell Suspension
Nutrients, Growth Factors
Implantationoperation
H
Variable Pore Size in Bone
4µm 220µm
Computer-Aided Design of Vasculature
We need a structure which will be space saving, strong and yet porous to allow growth of blood vessels…
Learn from nature and use a HONEYCOMB structure
3-D printing
From Dr. Chaozong Liu Printing video
3D Printing of Biocompatible Molds
Layers of wax and scaffold material build up in 3D
3D Printing of Biocompatible Molds The wax is dissolved at high pressure and low temperature in liquid carbon dioxide…
…this leaves a porous Scaffold
Why collagen?• 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.
Collagen processing• This technique allow
the control over pore size and porosity.
• Achieved through variation of freezing temperature and collagen dispersion concentration
Dry collagen scaffold
Advantages of Scaffold formation
• Control of the external structure:
Technology: CT/MRI CAD
Heart valve tissue engineering
Valve cells
Collagen scaffold of heart valve
Heart valve post- implantation
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