Cell therapy for heart disease: where are we in 2011?

Functional properties of bone marrow derived multipotent mesenchymal stromal cells are altered in heart failure patients, and could be corrected by adjustment of expansion strategies

BACKGROUND

Bone marrow multipotent mesenchymal stromal cells (BM-MMSC) considered as a prospective substrate for cell therapy applications, however adult stem cells could be affected by donor-specific factors: age, gender, medical history. Our aim was to investigate how HF affects the functional properties of BM-MMSC.

MATERIALS AND METHODS

BM-MMSC from 10 healthy donors (HD), and 16 donors with chronic HF were evaluated for proliferative activity, ability to differentiate, replicative senescence, expression of genes that affect regeneration and fibrosis. The effect of culturing conditions on efficiency of BM-MMSC expansion was determined.

RESULTS

HF-derived BM-MMSC demonstrated early decrease of proliferative activity and upregulation of genes that control both, regeneration and fibrosis: Tgf-β pathway, synthesis of ECM, remodeling enzymes, adhesion molecules. We assume that these effects were related to increase of frequency of myofibroblast-like CD146+/SMAα+ CFU-F in HF samples; (ii) low seeding density and hypoxia resulted in predominant purification and expansion of CD146+/SMAα- CFU-Fs. (iii) the activity of NPs system was downregulated in HF BM-MMSC;

CONCLUSIONS

downregulation of NP signaling in combination with upregulation of Tgf-β pathway in BM-MMSC would result in pro-fibrotic phenotype and make these cells non-effective for therapeutic applications; the corrections in culturing strategy resulted in 2(3)-2(7) increase of expansion efficiency.

The effect of cyclic stretch on maturation and 3D tissue formation of human embryonic stem cell-derived cardiomyocytes

The goal of cardiac tissue engineering is to restore function to the damaged myocardium with regenerative constructs. Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) can produce viable, contractile, three-dimensional grafts that function in vivo. We sought to enhance the viability and functional maturation of cardiac tissue constructs by cyclical stretch. hESC-CMs seeded onto gelatin-based scaffolds underwent cyclical stretching. Histological analysis demonstrated a greater proportion of cardiac troponin T-expressing cells in stretched than non-stretched constructs, and flow sorting demonstrated a higher proportion of cardiomyocytes. Ultrastructural assessment showed that cells in stretched constructs had a more mature phenotype, characterized by greater cell elongation, increased gap junction expression, and better contractile elements. Real-time PCR revealed enhanced mRNA expression of genes associated with cardiac maturation as well as genes encoding cardiac ion channels. Calcium imaging confirmed that stretched constructs contracted more frequently, with shorter calcium cycle duration. Epicardial implantation of constructs onto ischemic rat hearts demonstrated the feasibility of this platform, with enhanced survival and engraftment of transplanted cells in the stretched constructs. This uniaxial stretching system may serve as a platform for the production of cardiac tissue-engineered constructs for translational applications.

Guidance of stem cells to a target destination in vivo by magnetic nanoparticles in a magnetic field

Stem cells contribute to physiological processes such as postischemic neovascularization and vascular re-endothelialization, which help regenerate myocardial defects or repair vascular injury. However, therapeutic efficacy of stem cell transplantation is often limited by inefficient homing of systemically administered cells, which results in a low number of cells accumulating at sites of pathology. In this study, anti-CD34 antibody-coated magnetic nanoparticles (Fe3O4@PEG-CD34) are shown to have high affinity to stem cells. The results of hemolysis rate and activated partial thromboplastin time (APTT) tests indicate that such nanoparticle may be used safely in the blood system. In vitro studies showed that a nanoparticle concentration of 100 μg/mL gives rise to a significant increase in cell retention using an applicable permanent magnet, exerting minimal negative effect on cell viability and migration. Subsequent in vivo studies indicate that nanopartical can specifically bind stem cells with good magnetic response. Anti-CD34 antibody coated magnetic nanoparticle may be used to help deliver stem cells to a lesion site in the body for better treatment.

Increased potency of cardiac stem cells compared with bone marrow mesenchymal stem cells in cardiac repair

Whereas cardiac-derived c-kit(+) stem cells (CSCs) and bone marrow-derived mesenchymal stem cells (MSCs) are undergoing clinical trials testing safety and efficacy as a cell-based therapy, the relative therapeutic and biologic efficacy of these two cell types is unknown. We hypothesized that human CSCs have greater ability than MSCs to engraft, differentiate, and improve cardiac function. We compared intramyocardial injection of human fetal CSCs (36,000) with two doses of adult MSCs (36,000 and 1,000,000) or control (phosphate buffered saline) in nonobese diabetic/severe combined immune deficiency mice after coronary artery ligation. The myocardial infarction-induced enlargement in left ventricular chamber dimensions was ameliorated by CSCs (p < .05 for diastolic and systolic volumes), as was the decline in ejection fraction (EF; p < .05). Whereas 1 × 10(6) MSCs partially ameliorated ventricular remodeling and improved EF to a similar degree as CSCs, 36,000 MSCs did not influence chamber architecture or function. All cell therapies improved myocardial contractility, but CSCs preferentially reduced scar size and reduced vascular afterload. Engraftment and trilineage differentiation was substantially greater with CSCs than with MSCs. Adult-cultured c-kit(+)CSCs were less effective than fetal, but were still more potent than high-dose MSCs. These data demonstrate enhanced CSC engraftment, differentiation, and improved cardiac remodeling and function in ischemic heart failure. MSCs required a 30-fold greater dose than CSCs to improve cardiac function and anatomy. Together, these findings demonstrate a greater potency of CSCs than bone marrow MSCs in cardiac repair.

Cardiomyocytes in vitro adhesion is actively influenced by biomimetic synthetic peptides for cardiac tissue engineering

Scaffolds for tissue engineering must be designed to direct desired events such as cell attachment, growth, and differentiation. The incorporation of extracellular matrix-derived peptides into biomaterials has been proposed to mimic biochemical signals. In this study, three synthetic fragments of fibronectin, vitronectin, and stromal-derived factor-1 were investigated for the first time as potential adhesive sequences for cardiomyocytes (CMs) compared to smooth muscle cells. CMs are responsive to all peptides to differing degrees, demonstrating the existence of diverse adhesion mechanisms. The pretreatment of nontissue culture well surfaces with the (Arginine-Glycine-Aspartic Acid) RGD sequence anticipated the appearance of CMs' contractility compared to the control (fibronectin-coated well) and doubled the length of cell viability. Future prospects are the inclusion of these sequences into biomaterial formulation with the improvement in cell adhesion that could play an important role in cell retention during dynamic cell seeding.

Contemporary management and research directions in advanced heart failure: where are we going?

Advanced heart failure (AHF) is not a uniform disorder, but is rather a heterogeneous group of patients with varying clinical presentations and definitions. It is growing in magnitude and represents a major public health problem. Herein we describe contemporary care of the patient with AHF, novel medical therapies, and mechanical circulatory assist devices. We speculate where progress has been made and where the major gaps in knowledge remain. Clearly, there is ample opportunity for research and discovery to further advance the care of these very sick patients.