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 Current
Status
Future
Directions
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International Survey - Current Status
General
Tissue engineering research is a large and expanding activity
across the globe. In the United States, the first government grants
in this area were awarded in the mid-1980s. US Government funding
had increased to around $10 million by 2000 and had reached $50
million by 2002. The majority of funding, however, has come from
the private sector: $600 million in 2002 alone. Since 1995 it is
estimated that over $4.4 billion has been spent on tissue engineering
in the US. This has allowed the US to maintain a global lead in
tissue engineering research, but the inbalance between private and
public funding has brought its own set of problems to the industry.
Traditionally, the US has led the world in applied research, but
has had a lesser emphasis on fundamental aspects. The recent failure
of two major US-based tissue engineering enterprises led to a policy
re-evaluation resulting in a realignment of research funding to
more basic research. US research activities now more closely align
with Europe and Asia (particularly Japan) where government funding
is targeted to basic research with its intrinsic potential for developing
novel intellectual property. Research in Europe is focussed largely
on cell biology. Research in Japan is focussed on developing advanced
biomaterials.
Europe and Asia place a strong emphasis on research into autologous
cell therapies; where cells are removed from the patient, manipulated
and returned to the patient. This is achieved as free cells (eg
blood stem cell transplant) or with a supporting matrix (eg. bone,
corneal transplant). To date the majority of studies in Europe have
been based on the use of conventional biomaterials as supporting
scaffolds for the expansion and implantation of autologous cells.
In this situation, novelty arises from cellular rather than materials
developments. However, the realisation that conventional biomaterials
are often inherently unsuitable for many tissue engineering applications
has recently spurred research into the molecular design of novel
biomaterials.
Research in the US is aimed at developing autologous and allogeneic
therapies for regenerative medicine.
- Allogeneic therapies use donor tissue
- Autologous therapies use the patient’s own tissue
The use of stem cells is a controversial area of research globally.
Researchers in many countries, including Australia (through the
National Stem
Cell Centre) are investigating the technical challenges of this
approach and the legal, cultural and ethical issues associated with
using stem cells (especially embryonic cells). Until a consensus
community viewpoint is reached, research is predominantly focused
on the use of adult stem cells.
Virtually all tissue engineering applications require cells to
be grown outside the body. Specialised bioreactors are used for
this purpose. Considerable international research effort is aimed
at developing bioreactors for two- and three-dimensional cell culture.
Assuming the current problems of mass transport can be solved, enabling
cells in the centre of a mass of tissue to survive, there remains
the challenge of how this will occur following implantation. Similarly,
the biomechanical requirements of engineered tissues is a poorly
understood area across the globe, particularly in relation to how
these properties change as a degradable scaffold is degraded and
remodelled by cellular activity. The other side of this coin, the
effect of mechanical forces on cell behaviour, is being studied
by a number of groups across the world. Several groups are starting
to explore the application of genomics to tissue engineering, whereby
extensive databases are generated and the data then mined for specific
purposes. To date this technology has largely been aimed at drug
discovery, and the use of informatics in tissue engineering is still
at a very early stage globally.
The current status of tissue engineering activities
includes projects that are focused in key component areas of research
such as:
Biomaterial Scaffolds
Some of the laboratories that are active in this area include:
- Dept.
Bioengineering and Center for Nanotechnology, University of Washington,
Seattle, USA
- Dept. Bioengineering,
Rice University, Houston, USA
- Dept.
Chemical and Biological Engineering, Tufts University, Medford,
USA
- Center
for Clinical Bioengineering, University of Texas Health Science
Center, San Antonio, USA
- Institute
for Biomedical Engineering, ETH and University of Zurich, Lausanne,
Switzerland
- Tissue
Engineering Group, School of Pharamceutical Sciences, University
of Nottingham, Nottingham, UK
- Laboratory
for Biomedical Engineering, Department of Mechanical Engineering,
National University of Singapore, Singapore
- Department
of Biomedical Engineering, John Hopkins University, Baltimore,
MD, USA, and
- Bone
Tissue Engineering Initiative, Carnegie Mellon University, Pittsburgh,
USA.
Major questions being asked in this area include:
- How can the physical and chemical properties of scaffolds be
improved to:
- enable cells attach to the scaffold?
- provide growth factors and cytokines to stimulate the growth
of new cells in the scaffold?
- encourage blood vessels to grow (angiogenesis) and support
the new tissue within the scaffold?
- Prevent the body’s immune system rejecting the scaffold?
Clinical applications
of Tissue Engineering
Some of the laboratories that are active in this area include:
- Dept.
Chemical and Biological Engineering, Tufts University, Medford,
USA
- Dept. Orthopedic Surgery and Bioengineering, Mayo Clinic, Rochester,
USA
- Dept.
Biomedical Engineering, Tulane University, New Orleans, USA
- Parker
H. Petit Institute for Bioengineering and Bioscience, Georgia
Institute of Technology, Atlanta, USA
- Dept.
of Chemical Engineering and the Dept. of Biomedical Engineering,
University of Texas, Austin, USA
- Department of Plastic and Reconstructive Surgery, Salisbury
District Hospital, Salisbury, UK
- Laboratory for Cellular Therapeutics and Tissue Engineering,
Children's Hospital and Harvard Medical School, Boston, MA, USA
- Cell
& Tissue Engineering, Northern General Hospital and Department
of Engineering Materials, University of Sheffield, Sheffield,
UK, and
- UK
Centre for Tissue Engineering, Manchester and Liverpool, UK.
Major questions being asked in this area include:
- How can tissue engineering be applied to help repair or replace:
- Skin? Clinical application: Engineered skin could improve
the treatment of burns, diabetic foot ulcers, venous leg ulcers
and improve reconstruction surgery (e.g. for patients suffering
from cancer of the breast, head and neck)
- Bone and Cartilage? Clinical application: Engineered bone
and cartilage could improve the treatment of patients suffering
from diseases of the bone and joints (e.g. osteoporosis, rheumatoid
arthritis)
- Blood vessels? Clinical application: Engineered blood vessels
could improve the treatment of blocked blood vessels (e.g.
for patients suffering from heart disease or stroke)
- Nerves? Clinical application: Engineered nerves could improve
the treatment of patients suffering from spinal cord injuries
- Eye tissue? Clinical application: Engineered eye tissue
(e.g. cells from the cornea or retina) could improve the treatment
of patients suffering from loss of vision.
Cell Biology
Some of the laboratories active in this area include:
- Institute of
Biosciences and Bioengineering, Rice University, Houston, USA
- Departments
of Biomedical Engineering and Anesthesia, Duke University, Durham,
USA
- Division
of Bioengineering and Environmental Health and the Harvard-MIT
Division of Health Sciences and Technology, Cambridge, USA
- Centre for Tissue Engineering Research, School of Biosciences,
University of Westminster, London, UK
- Department
of Biomedical Engineering, Pudue University, West Layfayette,
USA
- Tissue
Repair & Engineering Centre, University College London, UK
- Institute
of Biomaterials and Biomedical Engineering, University of Toronto,
Toronto, Canada
- Tissue
Engineering Research Centre, National Institute of Advanced Industrial
Science and Technology, Hyogo, Japan, and
- Whitehead
Institute for Biomedical Research, Massachusetts Institute of
Technology, Boston, MA, USA.
Major questions being asked in this area include:
- How can tissue engineering improve our understanding of how
cells:
- Grow?
- Differentiate?
- Attach to scaffolds?
- Release and respond to cytokines?
- Move?
- Die?
- What types of cells offer the greatest promise for tissue engineering?
- The recipient’s own cells (autologous cells)
- Cells from another human (allogenic cells)
- Cells from another species (xenogenic cells)
Social, ethical and legal aspects of Tissue
Engineering
Some of the centres that are active in this area include:
- The
Canadian Stem Cell Network
- The
Centre for Social Ethics and Policy, Manchester, UK
- The
Institute for Medicine, Law and Bioethics, Liverpool, UK
- The
Lancaster Institute for Environment, Philosophy and Public Policy,
Lancaster, UK
- The
Novel Genetics Group, Dalhousie, USA
Major questions being asked in this area include:
- How should regulation of research in Tissue Engineering and
clinical application of Tissue Engineering proceed?
- What benefits and problems arise from commercialisation of research
activities in Tissue Engineering?
- To what degree does the public understand and support research
and clinical practice in Tissue Engineering?
- What are the ethical issues that arise in relation to the source
of stem cells used in Tissue Engineering?
- What are the ethical issues that emerge with Tissue Engineering,
regenerative medicine and xenotransplantation?
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