Cardiospheres and tissue engineering for myocardial regeneration: potential for clinical application.

Tissue engineering is an increasingly expanding area of research in the cardiovascular field that involves engineering, chemistry, biology and medicine. Cardiac tissue engineering (CTE) aims to regenerate myocardial damage by combining cells, matrix, biological active molecules and physiological stimuli. The rationale behind CTE applications is that in order to regenerate the ventricular wall after a myocardial infarction it is necessary to combine procedures that regenerate both cardiomyocytes and the extracellular matrix. The application of (stem) cells together with a matrix could represent an environment protected from the inflammatory and pro-apoptotic signals, a stemness/survival reservoir slowly releasing cells and factors promoting tissue regeneration and angiogenesis. This review will focus on the applications and advantages that CTE application could offer compared to conventional cell therapy.

Synthesis and characterization of a novel poly(vinyl alcohol) 3D platform for the evaluation of hepatocytes' response to drug administration.

Many whole cell-based assays in use today rely on flat, two-dimensional (2D) glass or plastic substrates that may not produce results characteristic of in vivo conditions. In this study, a three-dimensional (3D) cell-based assay scaffold was fabricated using a gas-in-foam templating technique. The scaffold was made of poly(vinyl alcohol), a water-soluble synthetic polymer with excellent film-forming, emulsifying, and biocompatible properties widely used in the biomedical field. The preliminary rheological studies on the solution of PVA and surfactant permitted us to disclose the significant physical parameters that influence the morphology of the ensuing materials. The scaffolds obtained were subjected to detailed analysis by light microscopy, Scanning Electron Microscopy (SEM), computed X-ray microtomography (µCT), infrared spectroscopy, and mechanical testing. Morphological investigations showed that the produced scaffolds are characterised by average void and interconnect diameters lying in the range of 200-300 and 30-150 µm, respectively, suitable for cell infiltration. Two different cross-linking procedures were adopted in order to modulate the mechanical properties of the PVA scaffolds. One made use of a bi-epoxide (PEGDGE), the other was based on glutaraldehyde (GA). The efficiency in terms of cross-linking density of the two procedures resulted in very different mechanical properties. Furthermore, in this article it is demonstrated how PVA foams can be processed into uniform, porous films suitable to be integrated with multi-well 2D culture plates in order to create a 3D analogue. The PEGDGE cross-linked scaffold was tested on C3A cells, a human hepatocyte cell line, representing an appropriate model for liver toxicity studies. Proliferation and cytotoxicity assays indicated good cell viability throughout the culture time, which was also confirmed by SEM analysis. Typical hepatic functions such as albumin and urea production and induction of Cyp3A4 enzyme activity following drug administration were satisfactory, thus proving the efficiency of this construct in maintaining specific liver functions.

Human cardiosphere-seeded gelatin and collagen scaffolds as cardiogenic engineered bioconstructs.

Cardiac tissue engineering (CTE) aims at regenerating damaged myocardium by combining cells to a biocompatible and/or bioactive matrix. Collagen and gelatin are among the most suitable materials used today for CTE approaches. In this study we compared the structural and biological features of collagen (C-RGD) or gelatin (G-FOAM)-based bioconstructs, seeded with human adult cardiac progenitor cells in the form of cardiospheres (CSps). The different morphology between C-RGD (fibrous ball-of-thread-like) and G-FOAM (trabecular sponge-like) was evidenced by SEM analysis and X-ray micro-tomography, and was reflected by their different mechanical characteristics. Seeded cells were viable and proliferating after 1 week in culture, and a reduced expression of cell-stress markers versus standard CSp culture was detected by realtime PCR. Cell engraftment inside the scaffolds was assessed by SEM microscopy and histology, evidencing more relevant cell migration and production of extracellular matrix in C-RGD versus G-FOAM. Immunofluorescence and realtime PCR analysis showed down-regulation of vascular and stemness markers, while early-to-late cardiac markers were consistently and significantly upregulated in G-FOAM and C-RGD compared to standard CSps culture, suggesting selective commitment towards cardiomyocytes. Overall our results suggest that CSp-bioconstructs have suitable mechanical properties and improved survival and cardiogenic properties, representing promising tools for CTE.