MICA:Characterization of graft-host cellular niche and crosstalk to augment cardiomyocyte-based cellular therapy to treat heart failure.
Lead Research Organisation:
UNIVERSITY OF CAMBRIDGE
Department Name: Pharmacology
Abstract
In a heart attack, the heart muscle dies which impairs the pumping ability of the heart. Heart failure ensues which carries 1 in 2 chances of death within 5 years of diagnosis. With an ageing population, heart failure is increasingly common with up to ~1 million UK citizens affected currently. At this moment, heart transplantation is the only definitive cure for heart failure but only ~200 heart transplants are performed each year in the UK. Thus, heart failure is a rapidly growing unmet clinical need.
Unfortunately, the heart is the least replicative organ in the body and is unable to restore its pumping action. Stem cells are cells that can turn into any cell type in the body, and so adding new heart muscle using a stem cell-based approach holds great promise to reinstate the pumping ability of the heart. Stem cell-based heart cells have been shown in animals to restore some heart muscle.
The epicardium, the outer layer of the heart, is essential for cardiac development as it contributes to supportive cells of the heart muscle and some blood vessels. Furthermore, the epicardial cells are constantly talking to the cardiac cells. This active to-and-fro communication between cells has been shown to be crucial for healthy heart development in mammals. We recently showed that combining stem cell-derived epicardium in combination with stem cell-derived heart cells improve heart function when delivered shortly after a heart attack.
However, stem-cell-based heart cells alone were unable to improve cardiac function when the heart attack was long ago with resultant scarring and heart failure. We reasoned that the host heart's scarred environment greatly challenges the stem cell-derived heart cells' ability to merge well (i.e engraft) with the host heart. When stem cell-derived heart cells merge well with the host tissue, the cells will form new heart muscle in continuity with the host tissue. This is required to successfully restore the pumping action of the failing heart.
Based on the data from our early studies, we hypothesized that the host heart is constantly talking to the engrafted heart cells and vice versa, as they attempt to restore the failing heart. The host-graft communication will be able to affect both host's and transplanted heart cells' behaviour. We also hypothesized that this communication is altered by different host environments (i.e. scarred) and when different types of heart cells are introduced into the host heart. So as to improve the pumping action of failing hearts, we need to understand the host-graft crosstalk at the genomic level. This will enable us to alter the host-graft communication, in order to improve the heart cells' engraftment and reinstate the pumping ability of the heart.
Thus, the key goals of this study are first to identify the unique genomic signatures of infarcted rat hearts with and without cell therapy. This will enable us to understand how the individual cells are talking to each other and changing their behaviour, in response to the environment and themselves. Secondly, we will identify a panel of small molecules that will improve the ability of the stem cells-derived heart cells to engraft and restore the heart's pumping ability. Thirdly, we aim to test whether the small molecules will improve the heart cells' engraftment within human cardiac tissues in the laboratory setting. We will also use ageing & infarcted human tissues to best simulate the clinical trials setting.
Testing the engraftment of human heart cells with complex human heart tissues in the laboratory is unique. This gives us the chance to address any challenges prior to clinical trials. Overall, this project is a key step to developing stem cells-derived heart cells as a commonplace heart failure treatment - a more accessible treatment alternative to heart transplantation.
Unfortunately, the heart is the least replicative organ in the body and is unable to restore its pumping action. Stem cells are cells that can turn into any cell type in the body, and so adding new heart muscle using a stem cell-based approach holds great promise to reinstate the pumping ability of the heart. Stem cell-based heart cells have been shown in animals to restore some heart muscle.
The epicardium, the outer layer of the heart, is essential for cardiac development as it contributes to supportive cells of the heart muscle and some blood vessels. Furthermore, the epicardial cells are constantly talking to the cardiac cells. This active to-and-fro communication between cells has been shown to be crucial for healthy heart development in mammals. We recently showed that combining stem cell-derived epicardium in combination with stem cell-derived heart cells improve heart function when delivered shortly after a heart attack.
However, stem-cell-based heart cells alone were unable to improve cardiac function when the heart attack was long ago with resultant scarring and heart failure. We reasoned that the host heart's scarred environment greatly challenges the stem cell-derived heart cells' ability to merge well (i.e engraft) with the host heart. When stem cell-derived heart cells merge well with the host tissue, the cells will form new heart muscle in continuity with the host tissue. This is required to successfully restore the pumping action of the failing heart.
Based on the data from our early studies, we hypothesized that the host heart is constantly talking to the engrafted heart cells and vice versa, as they attempt to restore the failing heart. The host-graft communication will be able to affect both host's and transplanted heart cells' behaviour. We also hypothesized that this communication is altered by different host environments (i.e. scarred) and when different types of heart cells are introduced into the host heart. So as to improve the pumping action of failing hearts, we need to understand the host-graft crosstalk at the genomic level. This will enable us to alter the host-graft communication, in order to improve the heart cells' engraftment and reinstate the pumping ability of the heart.
Thus, the key goals of this study are first to identify the unique genomic signatures of infarcted rat hearts with and without cell therapy. This will enable us to understand how the individual cells are talking to each other and changing their behaviour, in response to the environment and themselves. Secondly, we will identify a panel of small molecules that will improve the ability of the stem cells-derived heart cells to engraft and restore the heart's pumping ability. Thirdly, we aim to test whether the small molecules will improve the heart cells' engraftment within human cardiac tissues in the laboratory setting. We will also use ageing & infarcted human tissues to best simulate the clinical trials setting.
Testing the engraftment of human heart cells with complex human heart tissues in the laboratory is unique. This gives us the chance to address any challenges prior to clinical trials. Overall, this project is a key step to developing stem cells-derived heart cells as a commonplace heart failure treatment - a more accessible treatment alternative to heart transplantation.
Technical Summary
1 in 2 patients will die within 5 years from a heart failure diagnosis as there is no definitive cure to date. Human embryonic stem cells (hESC)-derived cardiomyocytes have great potential for cardiac repair and regeneration following myocardial infarction (MI) although challenges e.g. cell survival, engraftment, maturation and electrical integration remain. Successful 'primary remuscularization' of the infarcted heart was observed when (hESC)-derived cardiomyocytes were introduced soon after MI. Recently, we improved outcomes by co-delivering (hESC)-derived epicardium, a key stromal cell enabling the epicardial-myocardial crosstalk necessary for cardiac embryogenesis. However, the clinical challenge remains chronic heart failure. Previous attempts at remuscularizing the chronically infarcted hearts with (hESC)-derived cardiomyocytes alone have shown no benefit. We reasoned that the hostile environment of chronically infarcted myocardium would pose a greater engraftment challenge to the (hESC)-derived cardiomyocytes.
Our preliminary testing with alternative cellular approaches e.g. species-matched (neonatal rat cardiomyocytes) or combination cellular therapy (hESC-cardiomyocytes and hESC-epicardium) showed that cellular therapy could regenerate the chronically infarcted rat heart, albeit to a lesser extent than in the subacute MI setting.
We hypothesise that the graft-host tissue niche and its crosstalk play an instrumental role in determining successful cellular integration as well as overall cardiac functional recovery. Unfortunately, the graft-host cellular niche and its crosstalk remain poorly understood. In this application, we propose to define the graft-host niche and delineate their crosstalk in chronically failing rat hearts at the transcriptomic and spatial levels, in order to identify the principal barriers to donor-recipient integration. We will then test ways to improve cardiomyocyte integration using complex in vitro human heart systems.
Our preliminary testing with alternative cellular approaches e.g. species-matched (neonatal rat cardiomyocytes) or combination cellular therapy (hESC-cardiomyocytes and hESC-epicardium) showed that cellular therapy could regenerate the chronically infarcted rat heart, albeit to a lesser extent than in the subacute MI setting.
We hypothesise that the graft-host tissue niche and its crosstalk play an instrumental role in determining successful cellular integration as well as overall cardiac functional recovery. Unfortunately, the graft-host cellular niche and its crosstalk remain poorly understood. In this application, we propose to define the graft-host niche and delineate their crosstalk in chronically failing rat hearts at the transcriptomic and spatial levels, in order to identify the principal barriers to donor-recipient integration. We will then test ways to improve cardiomyocyte integration using complex in vitro human heart systems.
Publications

Arkley J
(2023)
A distractions capture tool for cardiac surgery and lung transplantation: impact on outcomes.
in Journal of cardiothoracic surgery

Ong L
(2023)
Epicardially secreted fibronectin drives cardiomyocyte maturation in 3D-engineered heart tissues
in Stem Cell Reports

Ong L
(2023)
Abstract P1131: Epicardially-secreted Fibronectin Promotes Hesc-cardiomyocytes' Maturation In 3d-engineered Heart Tissues.
in Circulation Research
Description | MRC/Astra Zeneca Research Fellowship - Cell Therapy & Gene Therapy |
Amount | £400,000 (GBP) |
Organisation | Medical Research Council (MRC) |
Sector | Public |
Country | United Kingdom |
Start | 07/2023 |
End | 08/2027 |
Description | Medical Research Council - Confidence in Concept (CiC) |
Amount | £50,000 (GBP) |
Organisation | Medical Research Council (MRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2023 |
End | 12/2023 |
Title | Assay development with hPSCs-cardiomyocytes for high-throughput compound screening |
Description | We optimized a 96-well plate assay of hPSCs-cardiomyocytes (cTNT >90% pure) for high-throughput compound screening using Yokogawa CellVovager8000 and live cell imaging. The phenotypic outputs include single-cell contractile force, calcium kinetics, and live-cell morphology. |
Type Of Material | Technology assay or reagent |
Year Produced | 2025 |
Provided To Others? | No |
Impact | A robust and optimized high-throughput assay involving hPSCs-cardiomyocytes is critical for compound screening and drug development. The hPSCs-cardiomyocytes can be highly variable regarding batch-to-batch differentiations and beat-to-beat contractility, which leads to a low signal-to-noise ratio and impairs target detection. We carefully optimized our cardiomyocyte-based assay, including cell density, plating material, proliferation rate, and live/dead ratio, to reduce as much biological and technical variability as possible so that our assays are highly consistent. This robust assay led to a strong target detection with a high signal-to-noise ratio. |
Title | 3D reconstruction of the heart and quantification of cardiomyocyte alignment at the graft-host interface |
Description | We developed a set of macros to reconstruct the rat heart from histological sections. This novel data analysis aims to characterize the orientation and alignment of connexin-43 within the engrafted tissue and the host myocardium. |
Type Of Material | Data analysis technique |
Year Produced | 2025 |
Provided To Others? | No |
Impact | The heart's pump function is reliant on three separate vectors, radial, longitudinal, and diagonal, underpinned by preserved tissue architecture. By reconstructing the heart in 3D from histological sections, we can study how the graft tissue integrates with the host myocardium to preserve the physiological pump function of the heart or not. This model is currently being optimized and will be published as part of an original research article. |
Description | Investigation the role of myc-cyclin T1 mod-RNA to induce cardiac regeneration in failing human hearts |
Organisation | AstraZeneca |
Department | Research and Development AstraZeneca |
Country | United Kingdom |
Sector | Private |
PI Contribution | I generated the idea and successfully won the MRC CIC grant as a co-applicant with Dr.Catherine Wilson and Dr.Stephen Large. I obtained the ethics approval as sponsored by Royal Papworth Hospital. |
Collaborator Contribution | Dr.Catherine Wilson showed that myc-cyclin T1 modRNA worked in rat models and she will produce the modRNA for this project. Dr.Stephen Large developed the ex-situ heart perfusion machine (mOrgan) to enable us to test the modRNA on explanted human hearts from heart transplant recipients. This machine was initially used to recover donor hearts for heart transplantation. |
Impact | This project is still ongoing. |
Start Year | 2023 |
Description | Murry-Sinha Collaboration |
Organisation | University of Washington |
Country | United States |
Sector | Academic/University |
PI Contribution | We developed the human embryonic stem cell (hESC)-derived epicardium as the novel technology and use this in combination with hESC-derived cardiomyocytes to regenerate the chronically failing rat hearts. We contributed the hESC-derived epicardium towards this collaboration. |
Collaborator Contribution | Our collaborators assisted with the cellular intramyocardial injections into the chronically infarcted rat hearts and consulted on the set-up of the cardiac regenerative chronic MI animal model at the University of Cambridge. They also consulted on the set-up of tissue-engineering models at University of Cambridge. |
Impact | 2 publications:- 1) Bargehr J, Ong LP, Colzani M, Davaapil H, Hofsteen P, Bhandari S, Gambardella L, Le Novère N, Iyer D, Sampaziotis F, Weinberger F, Bertero A, Leonard A, Bernard WG, Martinson A, Figg N, Regnier M, Bennett MR, Murry CE, Sinha S. Epicardial cells derived from human embryonic stem cells augment cardiomyocyte-driven heart regeneration. Nat Biotechnol. 2019 Aug;37(8):895-906. doi: 10.1038/s41587-019-0197-9. Epub 2019 Aug 2. PMID: 31375810; PMCID: PMC6824587. 2) Marchiano S, Hsiang TY, Khanna A, Higashi T, Whitmore LS, Bargehr J, Davaapil H, Chang J, Smith E, Ong LP, Colzani M, Reinecke H, Yang X, Pabon L, Sinha S, Najafian B, Sniadecki NJ, Bertero A, Gale M Jr, Murry CE. SARS-CoV-2 Infects Human Pluripotent Stem Cell-Derived Cardiomyocytes, Impairing Electrical and Mechanical Function. Stem Cell Reports. 2021 Mar 9;16(3):478-492. doi: 10.1016/j.stemcr.2021.02.008. Epub 2021 Feb 13. PMID: 33657418; PMCID: PMC7881699. |
Start Year | 2017 |
Description | Multidisciplinary Heart Failure Symposium |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Professional Practitioners |
Results and Impact | I organised a workshop for academic/industry scientists, physicians and physician-scientists to interact and exchange ideas on how to treat heart failure. This workshop was held as a series of talks together with breakout groups for further discussion about specific questions i.e. i) How to encourage collaboration between various sectors? , ii) How can we successfully hold public engagement? We received excellent feedback that this workshop has a healthy interaction between clinicians and scientists who are often working in different institutes. This workshop led to further collaborations. |
Year(s) Of Engagement Activity | 2023 |