Tissue engineering in heart and valve failure management

Dr. Alexander LyonSenior Lecturer and Consultant Cardiologist

Royal Brompton Hospital and Imperial College, London

Declaration of interest

• Nothing to declare

Overview

• Concepts for cardiovascular tissue engineering• Making a cardiac patch• Testing a cardiac patch in vivo• Heart valve engineering• Whole heart engineering• Clinical perspective

Fukushima, S. et al. Circulation 2007;115:2254-2261

Why do we need a patch in cell and tissue therapyRetention and Survival of grafted cells

Bone marrow cells - intramyocardial

Bone marrow cells - intracoronary

• In vitro culturing of cells on a biomaterial• Direct intramyocardial injection of cells with biomaterial scaffold• Direct intramyocardial injection of biomaterial alone• Direct intramyocardial injection of other agents such as proteins or gene therapy

Christman et al. (2006) J. Am. Coll. Cardiol

Delivery Options

a) a polymer mesh

Materials for myocardial scaffolds:ideal properties

• Mechanical properties matching host tissue

• Biocompatible

• Adherent

• Allow cell contraction/proliferation

• Vascularisation

• Biodegradable

• Non-toxic including degradation products

Materials to enhance cell attachment or survival

Material Advantages DisadvantagesNaturally occurring materials•Collagen•Alginate•Hyaluronic acid•Fibrin•Gelatin•Chitosan•Matrigel•Peritoneal membranes

BiocompatibilityPorousBiodegradableBioresorbable

Poor processibility

Poor mechanical properties

Possible immunogenic problems

Biodegradable synthetic polymers

•Poly(lactic acid)•Poly(ethylene terephthalate) = PED•Poly(glycerol sebacate) = PGS•Poly(lactic-co-glycolic acid)•Polypropylene fumarate•Poly(orthoesters)•Poly(anhydrides)

Good biocompatibilityOff-the-shelf availabilityGood processibility BioresorbableBiodegradable (wide range of rates)Added value from material tailoring• Controlled porosity• Mechanical support•Electrical conductivity•Controlled release of factors

Inflammation or nanotoxicity from degradation products

Loss of mechanical properties after degradation

Non-degradable synthetic polymers

Off-the-shelf availabilityNo foreign-body reactionsTailored mechanical properties

Effect of long term presence in the body

Biodegradable synthetic polymersPassive Stress-Strain Curves

Chen et al Biomaterials 2008 and 2010

(31)

(34)(30)

(33)(33)

(32)

E = 0.056 MPa

E = 0.22 MPa

PED/TiO2PGS@120C

PGS@110C

PED

Optimising engineered tissue properties

• Mechanical stimulation• Electrical stimulation• Physical patterning• Anti-apoptotic cocktail• Cell mix• Vascularisable scaffolds

Mechanical and electrical stimulation improveEngineered Heart Tissue maturation

Neonatal rat cardiomyocytes in collagenhuman embryonic stem cell-derived cardiomyocytes

T Eschenhagen, WH Zimmermann

1) Application of spin negative photo-resist polymers.

3) Cast PDMS mould added.

2) Exposure to ultraviolet (UV) light through

transparency mask – photolithography.

Silicon Wafer

Scale bar 20 µm Myosin Heavy Chain DAPI

10µm 4) PDMS mould with microgrooves.

10µm

4µm deep

5) Coat microgrooves with fibronectin.

Physical patterning to enhance cardiomyocyte maturityiPSC-CM onto fibronectin coated microgrooved polydimethylsiloxane (PDMS) scaffolds

fabricated using photolithography

Rao et al Biomaterials. 2013 Mar;34(10):2399-411

Rao et al Biomaterials. 2013 Mar;34(10):2399-411

Physical patterning to enhance cardiomyocyte maturity

Physical patterning to enhance cardiomyocyte maturity

Rao et al Biomaterials. 2013 Mar;34(10):2399-411

In vivo testing in preclinical models1 cm diameter patch, 0.5mm thick, sutured onto left ventricle, 2 weeks

(N=6-8 per column)

Control SO ST Qizhi 0

50

100

Max Pressurens

nsns

mm

Hg

Untreated PED PED/TiO2 PGS0

2500

5000

7500

10000

12500

dp/dt maxns ns

ns

mm

Hg/

sec

Untreated PED PED/TiO2 PGS0.0

2.5

5.0

7.5

10.0

12.5

ns nsns

LVEDP

mm

Hg

Untreated PED PED/TiO2 PGS

0

25

50

75

100

ns nsns

LVEF

mm

Hg

Untreated PED PED/TiO2 PGS

Hikaru Ishii

No obvious impact of sutured patch on normal cardiac function

Ex vivo MRI of cardiac scaffolds

PED biopolymer PED + TiO2

Dan Stuckey

Hearts imaged in vivo at 1 and 6 weeksPGS scaffold degraded

In vivo myocardial scaffold degradation

Stuckey et al Tissue Engineering 2010

Scaffolds attached infarcted rat heart epicardium (n = 12)Hearts imaged in vivo at 1 week at 11.7T

In vivo detection of scaffold motion

PED + TiO2 PGS

Stuckey et al Tissue Engineering 2010

Tissue engineered trileaflet valve made ofB PGA/P4HB seeded with human cells

C PCL scaffold seeded with human cellsPoly e-caprolactone (PCL):

biocompatible and biodegradablestrong mechanical properties

slow degradation rate

Brugmans, M.M., et al., Journal of tissue engineering and regenerative medicine, 2013.

Collagen deposition (in red)

Heart Valve Engineering

easy to setup and handlehigh productivity

average fibre diameter: 300 – 1100 nmfibre diameter span: 100-700 nm to 100-2000 nm

Heart Valve Engineering at Imperial CollegeJet spraying to make Polymer nanofibres

Cells follow fibre orientation

Sohier J, Carubelli I, et al Biomaterials. 2014 Feb;35(6):1833-44

Mechanical properties show the fibres are anisotropic but still not as strong as native tissue

Sohier J, Carubelli I, et al Biomaterials. 2014 Feb;35(6):1833-44

3D Printing – Tissue Engineering

Murphy and Atala Nature Biotechnol. 2014 Aug;32(8):773-85.

Murphy and Atala Nature Biotechnol. 2014 Aug;32(8):773-85.

3D Printing – Tissue EngineeringScaffold biosynthesis

Can we build a whole heart?Decellularised rat heart repopulated with neonatal cardiomyocytes

Clinical PerspectiveMyocardial tissue engineering

• Clinical unmet need• Efficacy

– Who to enrol first? • LVAD patients• CABG + LV aneurysmectomy• Large Anterior MI

• How to measure efficacy?– Physical

• Durability• New myocardium• Electrically coupled

– Functional impact• Regional• Global

– Clinical• Symptoms• Exercise tolerance• Hard endpoints

Clinical PerspectiveMyocardial tissue engineering

• Safety– Arrhythmias– Perforation/rupture– Immunosuppression– Tumour– Adhesions

Acknowledgements

• Professor Sian Harding• Professor Cesare Terracciano• Dr. Dan Stuckey (CMR)• Dr. Hikaru Ishii (in vivo studies)• Dr. Ivan Carubelli

(Valve studies)• Dr. Adrain Chester

(Valve studies)