No abstract

A.K. and M.A. performed the experiments repeatedly and collected and analyzed the data. L.A. and S.W. prepared and provided the fibrinogen solutions in varying concentrations and provided technical inputs. S.A.K., M.A., and B.J. wrote the manuscript and prepared all the figures. S.C.A. and L.S. performed rheology and analyzed the resultant data. V.T. and M.C. facilitated the CM and CF cultures, cell coupling experiments, and their microscopic imaging along with images and writing of relevant sections in the manuscript. J.A. and Y.I. provided the furfuryl-gelatin and performed cytotoxicity assay for Rose Bengal. All authors reviewed the manuscript and provided their consent for publication. The manuscript was written through individual contributions of all authors. All authors have given approval to the final version of the manuscript.

No abstract

Stem cells offer tremendous promise for regenerative medicine as they can become a variety of cell types. They also continuously proliferate, providing a renewable source of cells. Recently, it has been found that 3D printing constructs using stem cells, can generate models representing healthy or diseased tissues, as well as substitutes for diseased and damaged tissues. Here, we review the current state of the field of 3D printing stem cell derived tissues. First, we cover 3D printing technologies and discuss the different types of stem cells used for tissue engineering applications. We then detail the properties required for the bioinks used when printing viable tissues from stem cells. We give relevant examples of such bioprinted tissues, including adipose tissue, blood vessels, bone, cardiac tissue, cartilage, heart valves, liver, muscle, neural tissue, and pancreas. Finally, we provide future directions for improving the current technologies, along with areas of focus for future work to translate these exciting technologies into clinical applications.

In this study, we developed three-dimensional (3D) printed annular ring-like scaffolds of hydrogel (gelatin–alginate) constructs encapsulated with a mixture of human cardiac AC16 cardiomyocytes (CMs), fibroblasts (CFs), and microvascular endothelial cells (ECs) as cardiac organoid models in preparation for investigating the role of microgravity in cardiovascular disease initiation and development. We studied the mechanical properties of the acellular scaffolds and confirmed their cell compatibility as well as heterocellular coupling for cardiac tissue engineering. Rheological analysis performed on the acellular scaffolds showed the scaffolds to be elastogenic with elastic modulus within the range of a native in vivo heart tissue. The microstructural and physicochemical properties of the scaffolds analyzed through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total reflectance (ATR-FTIR) confirmed the mechanical and functional stability of the scaffolds for long-term use in in vitro cell culture studies. HL-1 cardiomyocytes bioprinted in these hydrogel scaffolds exhibited contractile functions over a sustained period of culture. Cell mixtures containing CMs, CFs, and ECs encapsulated within the 3D printed hydrogel scaffolds exhibited a significant increase in viability and proliferation over 21 days, as shown by flow cytometry analysis. Moreover, via the expression of specific cardiac biomarkers, cardiac-specific cell functionality was confirmed. Our study depicted the heterocellular cardiac cell interactions, which is extremely important for the maintenance of normal physiology of the cardiac wall in vivo and significantly increased over a period of 21 days in in vitro. This 3D bioprinted “cardiac organoid” model can be adopted to simulate cardiac environments in which cellular crosstalk in diseased pathologies like cardiac atrophy can be studied in vitro and can further be used for drug cytotoxicity screening or underlying disease mechanisms.