Epicardial application of cardiac progenitor cells in a 3D-printed gelatin/hyaluronic acid patch preserves cardiac function after myocardial infarction

Abstract

Cardiac cell therapy suffers from limitations related to poor engraftment and significant cell death after transplantation. In this regard, ex vivo tissue engineering is a tool that has been demonstrated to increase cell retention and survival. The aim of our study was to evaluate the therapeutic potential of a 3D-printed patch composed of human cardiac-derived progenitor cells (hCMPCs) in a hyaluronic acid/gelatin (HA/gel) based matrix. hCMPCs were printed in the HA/gel matrix (30 × 10⁶ cells/ml) to form a biocomplex made of six perpendicularly printed layers with a surface of 2 × 2 cm and thickness of 400 μm, in which they retained their viability, proliferation and differentiation capability. The printed biocomplex was transplanted in a mouse model of myocardial infarction (MI). The application of the patch led to a significant reduction in adverse remodeling and preservation of cardiac performance as was shown by both MRI and histology. Furthermore, the matrix supported the long-term in vivo survival and engraftment of hCMPCs, which exhibited a temporal increase in cardiac and vascular differentiation markers over the course of the 4 week follow-up period. Overall, we developed an effective and translational approach to enhance hCMPC delivery and action in the heart.

Introduction

An ischemic event in the myocardium has dire consequences for the heart since the death of cardiomyocytes within the infarcted area leaves the heart with less contractile elements. This shifts the pumping burden to the remaining viable myocardium, which can have deleterious consequences for patients suffering from the disease, potentially leading to the development of heart failure. Current therapeutic approaches do not provide patients with ways to repair the organ and instead focus on limiting secondary damages to slow down the progression of the disease [1], [2]. Therefore, end-stage heart failure patients often require heart transplantation, for which donor hearts are in short supply and carry risks of rejection [3]. Although the existence of endogenous stem cell populations in the heart has been documented [4], [5], these cells are unable to sufficiently repair the injury and restore the function of the heart.

The need to replenish the heart with new myocytes is of critical importance to avoid the chronic manifestation of the disease. In this regard, stem cell transplantation therapy offers a new therapeutic avenue to create de novo myocardium either in vitro or in vivo. A wide variety of stem cells have shown the ability to differentiate into cardiomyocytes. Of these, the multipotent Sca1+ cardiac-derived cardiomyocyte progenitor cells (CMPCs) offers a desirable combination of a patient-specific cell source with cardiogenic potential, both in vitro as in vivo [6], [7]. Besides direct involvement in tissue repair, the plethora of factors secreted by CMPCs can also activate endogenous stem cell pools, thereby making it a well suited cell type for the implementation of cardiac regenerative strategies [8], [9].

Although promising results have come out of pre-clinical and clinical studies [10], [11], [12], cardiac stem cell therapy still suffers from inefficient delivery, engraftment, and differentiation of cells in the myocardium [13], [14], [15]. Furthermore, during the progression of heart failure, extracellular matrix is also modified and replaced by scar tissue. Therefore, combining procedures aiming at regenerating both myocardial cells and the extracellular matrix could improve the effectiveness of cellular therapy. For this reason, hybrid therapies that include biomaterials and cells are being developed as potentially new therapeutic approaches for repairing myocardial tissue [15], [16]. We recently showed that tissue printing technology can be used with alginate in combination with CMPCs to create, in vitro, a cardiogenic patch with precise pore size and microstructure, which allows for better cell viability over time [17].

Here, we improved this tissue engineering approach by creating a cardiogenic scaffold of hCMPCs and a hyaluronic acid/gelatin (HA/gel) based biomaterial. The new biomaterial enhanced cell attachment and survival, and is suitable for tissue printing technology applications. We were able to build a customized patch that can harbor CMPCs without affecting their growth and differentiation potential. Furthermore, we demonstrated the in vivo applicability of the printed patch in a murine model of MI. The transplanted biocomplex sustained cell viability, leading to excellent cell survival and engraftment. Lastly, mice which received the scaffold showed improved cardiac function after MI.