Engineering soft/hard tissue interfaces

Lead Research Organisation: University of Birmingham
Department Name: Chemical Engineering

Abstract

Ligament and tendon injuries are relatively commonplace in patients of all age groups. These connective tissues enable joint locomotion and their injury can result in a debilitating loss of joint function and consequently a significant reduction in a patient's quality of life. Currently, ligament damage is repaired either by using a synthetic material to replace ligament function or by using tissue that is often harvested from elsewhere in the patients body (often from the hamstring or the quadriceps tendon). Failure of these repairs usually occur as a consequence of tensile stress concentrations at the interface with bone (enthesis) that can result in ligament detachment. In normally functioning ligaments, the interface with bone is specially structured with four continuous and yet distinct regions which protect the attachment point by ensuring that it is subject principally to compressive loads. In this work, we will seek to reproduce this structure by interfacing a tissue engineered ligament with a calcium phosphate based anchor material in a bioreactor system. The adhesion of the ligament to the ceramic structure will allow the mechanical conditioning of the tissue outside the body. By providing the necessary mechanical and chemical stimuli to a population of mesenchymal stem cells within the ligament, it may be possible to recreate the specialised enthesis structure in vitro. Ultimately, it is hoped that this multi-component tissue engineered structure will form an intimate bond with bone, resulting in the eventual regeneration of the ligament and enthesis in vivo leading to a better long term clinical outcome for the patient.

Technical Summary

Although many approaches have been applied clinically in the repair and augmentation of diseased and damaged bone, there are currently major issues associated with the repair of the soft/hard tissue interface. Such interfaces are essential for joint articulation and hence locomotion and a loss of their integrity can result in a significant reduction in the patient's quality of life. The anterior cruciate ligament, for example, may be repaired by mechanical fixation, the clinical success of this approach, however, is limited by poor fixation at the graft-bone junction the friability of which is the primary cause of graft failure. Failure typically occurs at the graft-bone junction as a result of localised stress concentrations at the interface between the tendon/ligament and bone, which are caused by a mismatch in modulus between the tissues of several orders of magnitude. In vivo, these stress concentrations are avoided by a complex fibrocartilaginous interfacial region (enthesis) that effectively transfers the load between the more and less compliant tissues. The proposed work will seek to produce a multi-tissue construct using a novel method for engineering a ligament-like structure in vitro, which will interface with a calcium phosphate based bracket of defined morphology. Ultimately, it is anticipated that this approach will allow us to engineer replacement ligaments and tendons in vitro for eventual implantation and clinical treatment of ligament/tendon damage.

Publications


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Bannerman A (2014) Imaging the hard/soft tissue interface. in Biotechnology letters
Jahromi SH (2011) Degradation of polysaccharide hydrogels seeded with bone marrow stromal cells. in Journal of the mechanical behavior of biomedical materials
Smith AM (2015) Nanoscale crystallinity modulates cell proliferation on plasma sprayed surfaces. in Materials science & engineering. C, Materials for biological applications
Wudebwe UN (2015) Exploiting cell-mediated contraction and adhesion to structure tissues in vitro. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
 
Title Ligament image 
Description Image presented at the 'images of research' exhibition, University of Birmingham, 15th March 2012 
Type Of Art Artwork 
Year Produced 2012 
Impact no actual impacts realised to date 
 
Description 1. We were able to engineer a multi-component structure with potential for ligament replacement using a cell-seeded fibrin gel with bone cement anchors at either end. It was anticipated that using bone cement would allow for the formation of an in tact hard/soft tissue interface that would improve the chance of clinical success of these implants. A hard/soft tissue interface was successfully produced that could last over 18 weeks in culture.

2. We have shown the propensity of several different bone replacement materials to form in vitro hard/soft tissue interfaces.

3. We developed an imaging methodology that can be used to study the formation of a hard/soft tissue interface in vitro.

4. We were able to identify several methods that could be used to increase the mechanical strength of the bone-to-bone ligament constructs to levels that were more appropriate for clinical use. These included chemical stimulation, mechanical stimulation and reinforcement.

5. We were able to develop bioreactor systems to enable mechanical stimulation of the bone-to-bone ligament constructs.

6. We showed that mechanical stimulation above 5% strain lead to matrix destruction, and used this knowledge to identify a stretch regime to increase the collagen content, and also the mechanical strength of the bone-to-bone ligament constructs.

7. We have used the findings of this work to allow us to lever almost £4m from MRC and Wellcome trust on scarring. This work was seen as important to scarring since ultimately the 3D model replicated the wound environment and has allowed us to screen dosages etc.
Exploitation Route The bone-to-bone ligament composite produced here may have a significant role in the future treatment of ligament repair. In addition, we also believe that the constructs can be used as a model of hard/soft tissue interface formation and maturation, and in the study of a variety of musculoskeletal disorders.
Sectors Healthcare,Pharmaceuticals and Medical Biotechnology
 
Description We have identified a molecule that prevents pathological ossification, we are now seeking funding to take this clinic.
First Year Of Impact 2016
Sector Healthcare
Impact Types Economic
 
Description Developing a model of pathological ossification
Amount £90,000 (GBP)
Funding ID NC/L001403/1 
Organisation National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) 
Sector Private
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 08/2014 
End 07/2017
 
Description Development of tissue engineered ligaments with titanium spring reinforcement
Amount £79,815 (GBP)
Funding ID 427 
Organisation Orthopaedic Research UK 
Sector Charity/Non Profit
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 01/2011 
End 01/2013
 
Description Development of tissue engineered ligaments with titanium spring reinforcement
Amount £79,815 (GBP)
Funding ID 427 
Organisation Orthopaedic Research UK 
Sector Charity/Non Profit
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 01/2011 
End 01/2013
 
Description Imaging of hard/soft tissue interfaces
Amount £1,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 03/2011 
End 08/2011
 
Description Imaging of tissue-engineered ligaments using MRI
Amount £1,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom of Great Britain & Northern Ireland (UK)
Start 03/2012 
End 08/2012
 
Description Research on ossification 
Organisation University of Oxford
Department Botnar Research Centre
Country United Kingdom of Great Britain & Northern Ireland (UK) 
Sector Academic/University 
PI Contribution We have some high-end chemical imaging techniques at Birmingham, which we have employed to shed light on pathological bone formation. We also developed (through a BBSRC project) a way to align extracellular matrix, such that it can resemble cortical bone. Mineralisation of this has allowed us to develop a model of bone formation (funded by NC3Rs).
Collaborator Contribution Biological expertise, particularly around the identification of osteocytes.
Impact We have developed a model under the NC3Rs project which has the structural and biological characteristics of bone. This has allowed us to screen for chemicals that might allow dispersion of the mineral phase and identify possible treatment methods. Grover has secured funding from the military to develop this into a therapy and from ORUK to biologically evaluate it.
Start Year 2014
 
Description Calcium Phosphate Cements 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach international
Primary Audience Participants in your research or patient groups
Results and Impact Talk given at University of Wuerzburg, Germany, 8th July 2011. This talk reported the use of calcium phosphate cements in the formation of a hard/soft tissue interface.

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description Engineering the hard/soft tissue interface 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Talk given at 2nd Biomaterials Symposium, Queen Mary Westfield, 30th November 2009 describing the work on the formation of an in vitro hard/soft tissue interface.

no actual impacts realised to date
Year(s) Of Engagement Activity 2009
 
Description Healthy Living: Helping you hold yourself together through ligament and tendon engineering. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Poster presented at the Universitas 21 Healthy Living Poster Conference, 20th November 2011. This poster described the work undertaken in generating functional tissues from bone-to-bone for potential implantation. Poster

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description Inorganic/organic composites for regenerating tissue structures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Talk given at the University of Huddersfield, 8th February 2012 describing the creation of a hard/soft tissue interface from inorganic and organic materials.

no actual impacts realised to date
Year(s) Of Engagement Activity 2012
 
Description Presentation at the British Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The talk received a lot of questions from the general public.

I have since been asked to talk on the importance of multidisciplinary science at a local school. A journalist in the crowd wrote up the research that I presented as an article in the Telegraph.
Year(s) Of Engagement Activity 2014
URL http://www.britishscienceassociation.org/british-science-festival/making-body-parts
 
Description Regenerating hard/soft tissue interfaces 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Seminar given at the Institut des NanoSciences de Paris 12th Septmeber 2011.

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description Repairing tissues: Taking cues from biology 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talk given at BPC Conference September 2009 stating the importance of forming in vitro hard/soft tissue interfaces for tissue repair.

no actual impacts realised to date
Year(s) Of Engagement Activity 2009
 
Description Snot and concrete: a tail of two convergent research areas 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Talk given at University of California, Davis, June 2010 reporting the formation of hard/soft tissue interfaces in vitro.

no actual impacts realised to date
Year(s) Of Engagement Activity 2010
URL http://www.reading.ac.uk:8081/news-and-events/releases/PR443893.aspx
 
Description Tissue engineering tendons and ligaments 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Schools
Results and Impact 6x15min talks on tissue engineering tendons and ligaments as part of a STEM (science, technology, engineering and maths) event for GCSE pupils.

no actual impacts realised to date
Year(s) Of Engagement Activity 2010
 
Description Tissue repair: exploiting biological cues 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Talk given at the Italian Institute of Technology, April 2010. This talk described the importance of forming hard/soft tissue interfaces for repair of soft tissues.

no actual impacts realised to date
Year(s) Of Engagement Activity 2010
 
Description Tissue repair: exploiting biological cues 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Talk given at Central South University, China, June 2010 describing the tissue engineered ligament system and the importance of formation of a hard/soft tissue interface.

no actual impacts realised to date
Year(s) Of Engagement Activity 2010