No abstract

Collagen is a widely used biomaterial in cardiac tissue engineering studies. However, as a natural material, it suffers from variability between batches that can complicate the standardization of culture conditions. In contrast, synthetic materials are modifiable, have well-defined structures and more homogeneous batches can be produced. In this study, several collagen-like synthetic self-assembling nanofiber hydrogels were examined for their suitability for cardiomyocyte culture in 2D and 3D. Six different nanofiber coatings were used in the 2D format with neonatal rat cardiomyocytes (NRCs) and human embryonic stem-cell-derived cardiomyocytes (hESC-CMs). The viability, growth, and functionality of the 2D-cultured cardiomyocytes were evaluated. The best-performing nanofiber coatings were selected for 3D experiments. Hydrophilic pH-sensitive nanofiber hydrogel coassembled with hyaluronic acid performed best with both NRCs and hESC-CMs. Hydrophilic non-pH-sensitive nanofiber hydrogels supported the growth of NRCs; however, their ability to promote attachment and growth of hESC-CMs was limited. NRCs also grew on hydrophobic nanofiber hydrogels; however, the cell-supporting capacity of these hydrogels was inferior to that of the hydrophilic hydrogel materials. This is the first study demonstrating that hydrophilic self-assembling nanofiber hydrogels support the culture of both NRCs and hESC-CMs, which suggests that these biomaterials hold promise for cardiac tissue engineering.

The interaction between different cardiac cells has shown to be important for critical biological properties including cell survival, proliferation, differentiation and function. The improvement of culture conditions with different cell types and to study their effects on cardiomyocyte viability and functionality is essential. For practical applications including general toxicity testing, drug development and tissue engineering it is important to study whether co-cultures have additional advantages over cardiomyocyte monoculture. Two multicellular in vitro cardiovascular constructs devoid of added biomaterial were developed in this study. In the first construct, neonatal rat cardiomyocytes (CM) were seeded on vascular-like network formed by human umbilical vein endothelial cells (HUVEC) and human adipose stromal cells (hASC). In the second construct, CMs were seeded on vascular-like network formed by HUVECs and human foreskin fibroblasts. The ability of these two vascular-like networks to support the viability and functionality of CMs was analyzed. Different culture media compositions were evaluated to support the development of optimal cardiovascular construct. Our results demonstrate that both vascular-like networks markedly improved CM viability and functionality. In the constructs, co-localization of CMs and vascular-like networks was seen. Multicellular constructs also allowed synchronized contractility of CMs. Serum-free medium supplemented with vascular endothelial growth factor and basic fibroblast growth factor was found to provide the most optimal conditions for cardiovascular construct as an entity. In conclusion, when combining a vascular-like network with CMs, the viability and functionality of CMs was markedly improved. The results suggest that the cardiovascular constructs developed provide a promising new tool for the assessment of toxicological and safety pharmacological effects of compounds in vitro.

The aim of this study was to scan through several biomaterials to find an optimal biomaterial to support the growth of cardiomyocytes. Neonatal rat cardiomyocytes were cultured on polylactide, chitosan, poly (1,8-octanediolco-citric acid), copolymer of poly(ethylene oxide terephthalate) and poly (butylene terephthalate), PuraMatrix™ and collagen. The suitability of biomaterials for cardiomyocyte culture was evaluated based on several parameters. The cells were characterized with time-lapse imaging, immunocytochemistry and LIVE/DEAD ® staining. Collagen gel was the best biomaterial. It supported well the growth, survival and functionality of the cardiomyocytes. Polylactide and chitosan membranes supported the cell growth and survival, but these biomaterials were too stiff for further cardiac applications. In conclusion, collagen gel is a good biomaterial to obtain a 3D structure to model heart tissue.