Lecture 5: Tissue Engineering & Regenerative Medicine PDF

Tissue Engineering & Regenerative Medicine Dr Rana Khalife Department of Biochemical Engineering University College London  Introduction The need for new strategies in healthcare What is Tissue Engineering (...

Tissue Engineering & Regenerative Medicine Dr Rana Khalife Department of Biochemical Engineering University College London  Introduction The need for new strategies in healthcare What is Tissue Engineering (TE)? What do we mean by Regenerative Medicine (RM)? What are the materials, devices and processes used in TE and RM? Why do future Engineers need to know about TE and RM  Learning Outcomes Understand the tissue engineering paradigm Understand the importance of tissue engineering and its emergence Define personalised medicine Importance of extracellular matrix (ECM) and scaffold Be able to differentiate between Tissue engineering and scaffold-based approaches Define the Function of ECM Identify and recognise the Issues and challenges in tissue engineering  Introduction The need for new strategies in healthcare Shortage of organs worldwide, together with other issues: Difficulties with organ preservation Patient rejection Immune response Personalised medicine Many drugs are not as efficient anymore Genetic and rare diseases Population-based clinical trials can not be applied  Introduction Organ Shortage in the UK Number of deceased donors & transplants in the UK & patients on the active transplant list 9000 8000 7000 6000 transplant list 5000 4000 3000 2000 transplants 1000 donors 0 https://www.organdonation.nhs.uk/helping-you-to-decide/about-organ-donation/statistics-about- organ-donation/  Introduction Organ Shortage in the UK: Facts & Figures Up to 1,000 people die every year due to a shortage of organs for transplant, that is 3 people every day There are currently 7,000+ people on the national waiting list for an organ transplant There are currently approx 140 children on the national waiting list for an organ transplant Last year only 3,000+ organ transplants were carried out in UK hospitals Each year 500,000 people die in the UK, but only around 3,500 die in circumstances where they can donate  Introduction Organ Shortage in the UK (2019 data) UK population: ~ 66,000,000 UK deaths: ~ 6,00,000 The difference between the number of Deaths in hospitals: ~ 290,000 deaths and potential donors is abysmal! Potential donors: 6,991 Eligible donors: 5,815 The number of transplants is more than double the number of donors Donation requested: 3,245 Consented donations: 2,279 Luckily transplants from living donors Actual doors: 1,600 are also possible, but still... Transplants: 3,941 Organs transplanted: 4,298 https://www.organdonation.nhs.uk/helping-you-to-decide/about-organ-donation/statistics-about- organ-donation/transplant-activity-report/  Introduction Organ Donation (UK) Over 25 Million people are on the NHS Organ Donor Register Every year around 1,400 people donate their organs across the UK when they die As of April 2019, approx 6,300 people are waiting for a transplant, while around 1,500 people have received a transplant  Introduction Organ Donation(UK): The Law Has Changed! The Opt Out System ‘…As of 20 May 2020, all adults in England (and Scotland) will be considered to have agreed to be an organ donor when they die unless they have recorded a decision not to donate or are in one of the excluded group…’ Wales introduced the opt out system in December 2015 and Northern Ireland still adopts the opt in system Excluded Group Children (under the age of 18 in England; under 16 in Scotland) People who lack the capacity to understand the law change and take the necessary action Visitors to the UK, and those not living here voluntarily People who have lived in the UK for less than 12 months before their death NB: Families will continue to be consulted, and the process will not go ahead without their support NHS, UK Opt In > Saves Lives!? Personalised Medicine  Personalised Medicine ‘A form of medicine that uses information about a person’s own genes or proteins to prevent, diagnose, or treat disease… also called precision medicine’ NCI Dictionary https://blog.crownbio.com/pdx-personalized-medicine  Personalised Medicine What is personalised medicine? A move away from a ‘one size fits all’ approach to the treatment and care of patients with a particular condition, to one which uses new approaches to better manage patients’ health and targets therapies to achieve the best outcomes in the management of a patient’s disease or predisposition to disease National Health Service, UK A medical model using characterization of individuals’ phenotypes and genotypes (e.g. molecular profiling, medical imaging, lifestyle data) for tailoring the right therapeutic strategy for the right person at the right time, and/or to determine the predisposition to disease and/or to deliver timely and targeted prevention European Commission Use of diagnostic tests to determine which medical treatments will work best for each patient. By combining the data from those tests with an individual’s medical history, circumstances and values, health care providers can develop targeted treatment and prevention plans Personalised Medicine Coalition …the focus is on identifying which approaches will be effective for which patients based on genetic, environmental, and lifestyle factors National Institute of Health, USA Personalised Medicine > Precision Medicine  Personalised Medicine Percentage of personalised/precision medical drugs approved annually 35 40 PMD Approval (%) 28 27 30 21 20 5 10 0 2005 2014 2015 2016 2017 Year Personalised medicine at FDA:m2018 report  Personalised Medicine Efficacy There are many drugs that are taken but don’t work anymore! Cholesterol-lowering drugs – only 1 in 20 are effective Arthritis medication – 1 in 4 in the US work Multiple sclerosis – 1 in 16 work Responsiveness Amongst people who share, for example, a particular mutation known to be targeted by a drug, many other factors can contribute to any individual responsiveness Research A change in mentality is needed – in the pharma industry, regulatory bodies, and clinicians Development Single-person clinical trials would be needed – this involves incredibly high costs and resources What is the alternative? Regenerative Medicine  Regenerative Medicine Regenerative medicine aims to replace or regenerate human cells, tissue or organs, to restore or establish normal function  Regenerative Medicine Therapeutic options Small Molecule Therapeutics Deliver drugs that stimulates endogenous regeneration (e.g., erythropoietin (EPO) stimulates RBC production) Cell Therapy Direct cell deliver (e.g., intra-coronary deliver – direct injection into the heart after a heart attack or stoke) Tissue engineering (TE)  Tissue Engineering (TE) What is TE? TE is an important field of regenerative medicine. It combines the principles of materials and cell transplantation to develop substitute tissues and/or promote endogenous regeneration TE aims to develop functional tissue substitutes that can be used for reconstructing damaged tissues or organs TE is an interdisciplinary science that involves the use of biological sciences and engineering to develop tissues that restore, maintain, or enhance tissue function TE is an interdisciplinary field aiming to repair or enhance the biological functions of injured tissues  Tissue Engineering (TE) What is TE? TE is… "an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve [biological tissue] function or a whole organ“ Langer & Vacanti, 1993 Why TE (general)? Induced tissue-specific regeneration overcome drawbacks of organ transplantation Donor shortage Need of immunosuppressive therapy Design of reliable (3D) in vitro models of healthy or pathological tissues and organs Drug screening Evaluation of new therapies Ethical issues considerations Animal testing Unreliable animal models Limited reproduction of specific human conditions Economic issues Research & Development Expensive (8-12 years, billions $$$) High failure development rate (in phase III)  Tissue Engineering (TE) What is TE? Production of tissue in vitro by seeding and growth of cells in the porous, absorbable scaffold Why is TE necessary? Most tissue fail to regenerate when they become injured or diseased Even tissue that have the capacity to undergo spontaneous regeneration often do not if critical sized defects are present (e.g., bone) Replacement of tissue with permanent implants is greatly limited  Principles of Tissue Engineering (TE) TE Paradigm Principles: Every tissue undergoes remodelling Isolated cells tend to reform tissue under the appropriate experimental conditions They only do this up to a certain extent when they are in suspension – they need a scaffold Tissues can not be implanted in large volumes – hence the scaffold to ‘guide’ the cell distribution  Tissue Engineering (TE) Strategies Scaffold provides cells with Cells (or cell Bioactive molecules induce cell substrate for growth factor substitutes) proliferation, differentiation and mechanical integrity post and metabolic activity transplantation TE Scaffold Signalling (matrix) molecules Scaffold associated to signalling processes may be used as drug delivery systems for inducing repair in vivo Advances in Biomaterials Sciences & Biomedical Applications  Tissue Engineering (TE) Limitations of TE Most tissue cannot yet be produced in vitro using TE Why is this? Complexity of architecture Lack of oxygen (passive or active) into the core of the tissue Even if the tissue engineered construct is implanted into the host, it may not engraft and remodel to integrate with host tissue  Cell Therapy Stem Cells Differentiated cells are problematic Differentiated cells are specialized cells committed to perform a specific function Limited proliferation potential Availability Stem cells are uncommitted cells that remain so until they receive signals to differentiate into specialized cells Small quantity of start material can be expanded to produce large quantities of cells for therapeutic benefit They can be directly injected into the patient (cell therapy) or on a tissue-engineered scaffold Scaffold in TE  Scaffold in TE Scaffolds There are 4 categories of scaffolds used in TE 1) Pre-made 3) Confluent cell sheets with porous scaffold excreted extra cellular matrix 2) Decellularised 4) Cells encapsulated with extracellular matrix self-assembled hydrogel  Scaffold in TE Pre-made porous scaffold for cell seeding Raw Materials Synthetic or natural biomaterials Processing or fabrication Incorporation of porogens in solid materials; solid technology free-form fabrication technologies; techniques using woven or non-woven fibres Strategy to combine with cells Seeding Strategy to transfer to host tissue Implantation Advantages Most diversified choices for materials; precise design for microstructure and architecture Disadvantages Time consuming cell seeding procedure; non- homogeneous distribution of cells Preferred applications Soft and hard tissue; load-bearing tissue  Scaffold in TE De-cellularised extracellular matrix (ECM) for cell seeding Raw materials Allogenic or xenogenic tissue Processing or fabrication technology Decellularisation technology Strategy to combine with cells Seeding Strategy to transfer to host tissue Implantation Advantages Most nature-stimulating scaffolds in terms of composition and mechanical properties Disadvantages Non-homogeneous distribution of cells; difficulty in retaining all ECM; immunogenicity upon complete decellularisation Preferred applications Tissue with high ECM content; load-bearing tissue  Scaffold in TE Confluent cells with secreted ECM Raw materials Cells Processing or fabrication technology Secretion of ECM by confluent cells Strategy to combine with cells Cells present before ECM secretion Strategy to transfer to host tissue Implantation Advantages Cell-secreted ECM is biocompatible Disadvantages Need multiple laminations Preferred applications Tissues with high cellularity; epithelial tissue; endothelial tissue; thin layer tissue  Scaffold in TE Cells encapsulated in self-assembled hydrogel Raw materials Synthetic or natural biomaterials able to self- assemble into hydrogel Processing or fabrication technology Initiation of self-assembly process by parameters such as pH and temperature Strategy to combine with cells Cells present before self-assembly Strategy to transfer to host tissue Injection Advantages Injectable; fast and simple one-step process; intimate cell and material interactions Disadvantages Soft structures Preferred applications Soft tissues Clinical Examples of TE  Examples of TE As of April 2020, there were 49 clinical trials in progress relating to tissue engineering Replacement of: Tracheal Bladder Vascular Tissue Dental Hair Skin Hip/Knee (cartilage) … https://clinicaltrials.gov/ct2/results?recrs=&cond=tissue +engineering&term=&cntry=&state=&city=&dist=  TE: Tracheal Replacement ‘Surgeons in Spain have carried out the world's first tissue-engineered whole organ transplant - using a windpipe made with the patient's own stem cells’ BBC, 19th Nov, 2008 Dilemma Patient contracts TB TB destroyed part of her trachea (windpipe) Difficulty breathing Lungs prone to infection Solution – Tracheal Replacement Trachea (windpipe) removed from dead donor patient Removed trachea is decellularised Stem cells obtained from patients’ bone marrow and cultivated to from cartilage cells Epithelial cells removed and cultivated from patient Decelluarilsed trachea seeded with cartilage and epithelial cells Immunosuppressant drugs unnecessary Trachea hybrid created in a bioreactor Engineered trachea cut and shaped and grafted onto patients bronchus (destroyed area) Outcome No breathing issues Normal daily life returned to patient  TE: Tracheal Replacement trachea removed from deceased donor seed scaffold with trachea is cartilage cells derived decellularised from patients’ stem cells add epithelial cells from patient trachea scaffold patient transplant maturate in engineered trachea a bioreactor cut and shaped  TE: Urinary Bladder General strategies for Tissue engineered Bladder urothelial cells cell extraction Cell culture cell seeding biopsy Smooth muscle cells Bladder Replacement biodegradable scaffold cell culture in implant a bioreactor grafting bioengineered tissue  TE: Vascular Tissue cells are extracted and isolated e.g., smooth muscle cells, cell expansion stem cells, fibroblasts in culture biopsy transplantation polymer processed cells seeded into a porous scaffold into scaffold tissue engineered vascular graft (TEVG) construct matured in a bioreactor  TE: Vascular Tissue cells are extracted and isolated e.g., smooth muscle cells, cell expansion stem cells, fibroblasts in culture biopsy cells and polymer transplantation material mixed and shaped into a mould tissue engineered vascular graft (TEVG) construct matured in a bioreactor Future of TE  TE Considerations Issues to be addressed Should tissue be produced in vitro for later implantation or in vivo? What scaffold should be used? Choice of material, poor size, absorbability, mechanical strength How will it be manufactured? What cells should be used? Cell source Can they be expanded in vitro to achieve the required cell number without altering their phenotype? What regulators are required to facilitate cell proliferation and/or differentiation and matrix synthesis  TE Considerations Requirements for TE Histological & Biochemical Accurately match the architecture of the host tissue But, complete analysis is difficult as don’t know how architecture will be modified when implanted and re-modelled Functional Has to acquire functional propertied that are the same (or very similar) as host tissue But, difficult to measure all properties – which is most important and how/what to measure? Clinical Restoration of a patients’ quality of life that was lost due to injury/disease Pain relief Regain function of tissue (e.g., mobility, sight, bladder control, etc)  Emerging Technologies in TE Organ-on-a-chip Microfluidics Data Collection Cell Sheet Technology Diagnosis Patient Patient Cells Site of Repair Cell Screening Data Collection Gene Editing Machine Learning Cell Isolation 3D Bio-printing Gene Editing 3D Bio-printing Patient Cell Expansion Tissue Construct Bioreactor Bioreactor Data on Quality Tissue Construct Tissue Profiling Role of Biochemical Engineers in Regenerative Medicine  Role of Biochemical Engineers in RM Translating Science to Society How can these new therapies be produced in commercial quantities? What are the best materials that can be used for tissue regeneration? What are the devices that help in the discovery of these new therapies? What are the regulations associated with their large-scale production? What are the product attributes that are to be achieved to efficiently treat patients?  Concluding Remarks Tissue engineering is still hindered by many challenges which have an impact on product release These challenges include: Complexity of the organ structure Vascularisation of the tissue The choice of cells Properties of the biomaterials Mechanical strength Compatibility biodegradability The cost of the therapy The duration of the process Regulatory bodies  Reading List Articles/Reviews Armstrong & Stevens, Tissue Eng (part A) 25, (9-10) (2019) Caddeo et al Front Bioeng Biotech, 5, 40 (2017) Chan & Leong, Eur Spine J 17, S467-S479 (2008) Dugger et al, Nat Rev Drug Discov, 17, 183-196 (2018) Han et al Fron Bioeng Biotech, 8, 83 (2020) Inamdar et al, Curr Opin Biotec, 22, 681-689 (2011) Khademhosseini et al, Nat Protocol, 10, 1775-1781 (2016) Kular et al, J Tissue Eng, 5, 1-17 (2014) Matai et al, Biomaterials, 226 (2020) Pashneh-Tala et al, Tiss Eng (Part B), 22, 68-100 (2016) Rahaman & Mao, Biotech Bioeng 91.3, 261-284 (2005) Seifu et al, Nat Rev Cardio, 10, 410-421 (2013) Zhang et al, Nat Rev Materials, 3, 257-278 (2018) Zhou et al, Theranostics, 7, 2509-2523 (2017) Websites https://www.organdonation.nhs.uk/ https://www.england.nhs.uk/healthcare-science/personalisedmedicine/ https://www.fda.gov/medical-devices/vitro-diagnostics/precision-medicine http://www.personalizedmedicinecoalition.org/Userfiles/PMC- Corporate/file/PM_at_FDA_2017_Progress_Report.pdf Thank you!