Skip to main content
European Commission logo print header

Stem Cell Cocooning for Targeted Cardiac Cell Therapy

Final Report Summary - STEM CELLS COCOONING (Stem Cell Cocooning for Targeted Cardiac Cell Therapy)

Final Report (January 2015)
EU FP7 IIF Project Number: 302782, Title: Stem Cell Cocooning
Researcher: Asst. Prof. Mehrdad RAFAT, mrafat@liu.se Scientist in Charge: Prof. Marek JAN LOS, marek.los@liu.se

1. Project summary: Stem cell therapy is believed to be the most viable method for restoration of cardiac function after Myocardial Infarction (MI), the leading cause of death in Europe and globally. Despite numerous attempts at injecting stem cells into post-MI heart to affect regeneration, the consensus is that cell death induced by the lack of contact between the cells and the tissue scaffold during injection, the harsh environment at the injection site, and powerful myocardial contractions cause massive cell loss rendering the therapy ineffective. In this project we have attempted to enhance treatment efficacy by cocooning of stem cells in bioengineered collagen-based microspheres. The cocoon provides the tissue support for cell survival, promotes integrin up-regulation for better engraftment of the cells onto the heart tissue, and protect the cells from the harsh post-MI environment. During this project, we developed hybrid microspheres through the combination of the naturally occurring, clinical grade, collagen (porcine Type I) with alginate. We studied the sphere formation, harboring Porcine Arterial Endothelial (PAE) cells, induced pluripotent stem cells (iPS) and cardiomyocytes, while assessing cell viability, and degradability of the composite microspheres. A system of multifactorial design and mathematical modelling was used to optimize the microspheres formulations, determine the impacts of multiple factors on size, roundness of spheres, and cell viability and release time simultaneously and to predict their behaviors (Fig. 1). For the optimum formulation with a collagen to alginate mass ratio of 1, 85% of the cells were found viable six days post-encapsulation. The optimum microsphere formulation was injected in mice subcutaneously. The spheres were degraded and reduced in size by 90% after 5 days. This research provides a good platform for enhancing cells viability and survival and their therapeutic efficiency for future treatment of myocardial infarction.

2. Overview of results: We have developed a novel hybrid microspheres system for single and multiple cells encapsulation as a cell delivery vehicle. Microspheres produced by an air micronization technique and ionic cross-linking of clinical grade porcine collagen and Sodium Alginate by divalent cations (Ca2+) towards developing injectable cell encapsulation materials to treat a myocardial infarct. Using a multifactorial design, the impact of various experimental condition(Fig. 2G), iopolymer composition and flow rate, air flow rate, and particle travel distance on microspheres’ size (Fig.2 A-C), sphericity, morphology, degradability (Fig.2 D-F), and cell viability were investigated as shown in Fig.2 G-I.

Various cell types including iPS cells (Fig.2G) cardiomyocytes (Fig 2H), and PAE cells (Fig 2I) were successfully encapsulated at high viability rates evaluated by Live/Dead staining. Fibroblast growth factor (FGF-2) was also encapsulated in the microspheres for FGF-2 control release and enhanced vascularization. The composite material showed cell body formation and enhanced vasculature tube formation when seeded with PAEover cell release (Fig. 2D-F) and rthermore, the addition of collagen allowed for multiple routes for sphere degradation leading to potentially greater control over cell release (Fig [*]2D-F[/*]) and biocompatibility once delivered. After injecting the optimum FGF-2 incorporated cell cocoons into B6-mice subcutaneously no immunological response was detected suggesting that the microspheres were well-accepted in vivo.

3. Conclusions: The synthesis of hybrid collagen-alginate cocoons was successfully achieved through a co-axial air-micronization method. The diameter and roundness of these spheres could be controlled through manipulation of air-flow rate, collagen to alginate ratio, and air-gap distance. A systemic multifactorial design method was utilized to design the experiments and investigate the impacts of various parameters on microspheres properties. The iPS cells and cardiomyocytes encapsulated in the microspheres were viable at a high viability rate of 85% over six days in culture. This work provides a good platform for moving into animal models toward enhancing cells therapeutic efficiency for treating myocardial infarction.


4. The socio-economic impacts of the project: Cardiovascular Diseases (CVD) are the number one cause of death globally. An estimated 17.1 million people died from CVD in 2004, representing 29% of all global deaths. Each year CVD causes over 4.35 million deaths in Europe, which is nearly half of all deaths in the continent (49 percent). The socio-economic costs of CVD are considerable and overall CVD is estimated to cost the EU economy EU €206 Billion a year. CVD in its advanced stage is characterized by the presence of atherosclerotic plaque (AP). MI, commonly known as a heart attack, is the interruption of blood supply to part of the heart, causing heart cells to die. This is most commonly due to blockage of a coronary artery following the rupture of a vulnerable AP. MI causes fibrotic scar formation and impaired cardiac function. Heart transplantation is the ultimate solution to end-stage heart failure. However, due to the shortage of organ donors and complications associated with immune suppressive treatments, development of new strategies to help regenerate the injured heart and rehabilitate its functioning is necessary. Cell transplantation has drawn a lot of attention as a promising non-invasive therapy for ischemic heart disease and failure. Recent studies have shown that cell transplantation can be an effective treatment for MI. Despite the fact that delivery of cells holds the potential to regenerate damaged tissue and restore organ function, a gradual diminution in number and strength of the cells at the transplantation site has been reported. In fact, it has been estimated that almost nine out of ten transferred cells will eventually die. This phenomenon is likely because of cell stress and the lack of contact between the cells and the tissue scaffold at the site of delivery and is considered to present a limit to efficacy of the treatments. Through this project, we developed a method to enhance cell survival by using a combined approach bringing cells and bioengineered materials together to pave the way for addressing a universal health problem. Stem cells along with collagen-based microcapsules would serve several therapeutic purposes including a biomechanical support, an efficient cell delivery vehicle, and a biodegradable porous scaffold that would facilitate cell survival and grafting needed for repair and re-modeling of damaged heart muscle. Incorporation of growth factors such as FGF-2 into microspheres will improve angiogenesis for better rehabilitation of the cardiac muscle functions. Even if we can improve the cell survival by 10% through this cocooning technique, it will have a significant impact on cardiac functions resulting in better quality of life for patients and reduced cost of treatment.