# Engineering mammalian cells for detection and treatment of cardiac injury

## TL;DR

Scientists engineered human cells to detect heart injury markers and release a clot-dissolving drug, offering a new approach for treating heart attacks.

## Contribution

A novel cell-based system that senses cardiac injury and releases thrombolytic drugs in a controlled, inducible manner.

## Key findings

- Engineered cells respond to cardiac troponin I by expressing thrombolytic tenecteplase.
- Encapsulated cells dissolved fibrin clots in a cTnI-dependent and doxycycline-repressible manner.
- The system includes a drug-controlled off-switch for terminating therapeutic actions.

## Abstract

Early detection of myocardial abnormalities or other ischemic heart diseases is critical for effective treatment. Here, we aimed to engineer a cell-based system to sense cardiac troponin I (cTnI), an early marker of acute myocardial infarction (AMI), and respond by releasing a thrombolytic agent. To detect cTnI, we engineered a chimeric troponin receptor (TropR) that contains extracellular single-chain variable fragments (scFvs) and signals via intracellular domains of interleukin 6 receptor subunit beta (IL6RB), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor 1 (FGFR1), fibroblast growth factor receptor 2b (FGFR2b) or vascular endothelial growth factor receptor 2 (VEGFR2) that are associated with cardioprotective signaling. cTnI-dependent TropR functionality was confirmed in human embryonic kidney (HEK)-derived cell lines as well as iPSC-derived cardiomyocytes, and enabled rapid, reversible, tunable control of gene expression via synthetic-signaling-specific promoters. We then constructed monoclonal cell lines for cTnI-induced secretion of the thrombolytic protein tenecteplase (TNK), together with an off-switch triggered by FDA-approved doxycycline. We selected a clone, designated CardioProtect, whose sensitivity was optimized to detect human AMI-relevant cTnI levels. To validate thrombolytic efficacy, we established an ex vivo blood culture system and show that alginate-microencapsulated CardioProtect cells triggered complete lysis of fibrin clots in a strict cTnI-inducible, doxycycline-repressible manner. This closed-loop strategy serves as a proof-of-concept for using cell therapy in the early detection and treatment of AMI.

Human cells were programmed to sense cardiac troponin I (cTnI), an early marker of myocardial injury, and release the thrombolytic drug tenecteplase upon cTnI stimulation. Encapsulated CardioProtect could act as clot-dissolving microreactors for future cardioprotective cell therapies.

cTnI-sensing receptors (TropR) were engineered to convert early signals of myocardial injury into tunable transgene expression.Human cells carrying TropR and TropR-depedent gene regulation systems (“CardioProtect”) enable coordinated cTnI-stimulated Tenecteplase expression in closed-loop.Encapsulated “CardioProtect” cells respond to clinically relevant cTnI levels by secreting Tenecteplase levels capable of dissolving fibrin clots in culture.A drug-controlled OFF switch was integrated to terminate or interrupt therapeutic actions on demand.Implantation of CardioProtect may enable detection and treatment of cardiac injury in the future.

cTnI-sensing receptors (TropR) were engineered to convert early signals of myocardial injury into tunable transgene expression.

Human cells carrying TropR and TropR-depedent gene regulation systems (“CardioProtect”) enable coordinated cTnI-stimulated Tenecteplase expression in closed-loop.

Encapsulated “CardioProtect” cells respond to clinically relevant cTnI levels by secreting Tenecteplase levels capable of dissolving fibrin clots in culture.

A drug-controlled OFF switch was integrated to terminate or interrupt therapeutic actions on demand.

Implantation of CardioProtect may enable detection and treatment of cardiac injury in the future.

Human cells were programmed to sense cardiac troponin I (cTnI), an early marker of myocardial injury, and release the thrombolytic drug tenecteplase upon cTnI stimulation. Encapsulated CardioProtect could act as clot-dissolving microreactors for future cardioprotective cell therapies.