Cell Therapy with Embryonic Stem Cell-Derived Cardiomyocytes Encapsulated in Injectable Nanomatrix Gel Enhances Cell Engraftment and Promotes Cardiac Repair

Abstract

A significant barrier to the therapeutic use of stem cells is poor cell retention in vivo. Here, we evaluate the therapeutic potential and long-term engraftment of cardiomyocytes (CMs) derived from mouse embryonic stem cells (mESCs) encapsulated in an injectable nanomatrix gel consisting of peptide amphiphiles incorporating cell adhesive ligand Arg-Gly-Asp-Ser (PA-RGDS) in experimental myocardial infarction (MI). We cultured rat neonatal CMs in PA-RGDS for 7 days and found that more than 90% of the CMs survived. Next, we intramyocardially injected mouse CM cell line HL-1 CMs with or without PA-RGDS into uninjured hearts. Histologic examination and flow cytometry analysis of digested heart tissues showed approximately 3-fold higher engraftment in the mice that received CMs with PA-RGDS compared to those without PA-RGDS. We further investigated the therapeutic effects and long-term engraftment of mESC-CMs with PA-RGDS on MI in comparison with PBS control, CM-only, and PA-RGDS only. Echocardiography demonstrated that the CM-only and CM+PA-RGDS groups showed higher cardiac function at week 2 compared to other groups. However, from 3 weeks, higher cardiac function was maintained only in the CM+PA-RGDS group; this was sustained for 12 weeks. Confocal microscopic examination of the cardiac tissues harvested at 14 weeks demonstrated sustained engraftment and integration of mESC-CMs into host myocardium in the CM+PA-RGDS group only. This study for the first time demonstrated that PA-RGDS encapsulation can enhance survival of mESC-derived CMs and improve cardiac function post-MI. This nanomatrix gel-mediated stem cell therapy can be a promising option for treating MI.

Towards the standardization of stem cell therapy studies for ischemic heart diseases: Bridging the gap between animal models and the clinical setting

“…Also related to gestation, MSCs obtained from fetal heart tissue (fC-MSC) and embryonic stem cells (ESC) have been proposed as alternative multipotent cells with the ability to differentiate into CMs, endothelial and smooth muscle cells. However, the use of such cells is obviated by evident ethical dilemmas [52][53][54][55].…”

“…After being administered, cells can be nearly gone as soon as 1 to 3 days after transplantation [44,45]. However, some authors reported signs of stem cell survival up to 1 week [8,16,60,100,104], 1 month [14,18,23,27,30,37,46,52,67,105] and, most strikingly, up to 1 year [26]. When retained cells are quantified, we find that less than 3% of the stem cells survive more than 4 weeks [59,70] and that percentage drops to levels below 1% when the assessment is made 16 weeks after transplantation [106].…”

“…In addition to the naturally occurring matrices, researchers have been manufacturing other more laborious scaffolds such as NapFF-NO hydrogel (naphthalene covalently conjugated to a short peptide, FFGGG, and β-galactose caged nitric oxide (NO) donor) [113], selfassembled biodegradable peptide amphiphile (incorporating cell adhesive ligand RGDS) nanomatrix [52] or plasma-functionalized electrospun poly-ε-caprolactone (PCL) fibers [114]. In NapFF-NO hydrogel, the sustained release of NO, through the activity of injected β-galactosidase, adds to the paracrine activity of the encapsulated ADMSC, enhancing angiogenesis.…”

“…Despite its potential, this technique brings another layer of complexity to the therapy by requiring co-administration of β-galactosidase. The use of self-assembling peptides (SAP) as reported by Ban et al [52], beyond giving a support for stem cells, promotes their adhesion due to its RGDS domain and allows a sustained release due to the presence of a matrix metalloproteinase-2 degradable domain, that is gradually cleaved as a result of the inflammation inherent to an ischemic myocardium. With the use of SAP, it was possible to enhance ejection fraction and FS, as well as to reduce fibrosis in the used model of AMI.…”

Nano-Engineered Biomaterials for Tissue Regeneration: What Has Been Achieved So Far?

“…Peptide nanofiber-based scaffolds represent a bottom-up approach to fiber formation where small, chemically synthesized oligopeptides are the building blocks. A benefit of this approach is that the peptide building block sequence can be customized to the needs of the application, as seen in a study by Ban et al in which amphiphilic peptides were synthesized with a matrix metalloproteinase-2 (MMP2) and integrin binding cell adhesion sequence to replicate native cues for CM attachment prior to material injection (Ban et al, 2014). Further work has aimed to enhance the angiogenic capacity of self-assembling peptides.…”