Bioprinted gelatin hydrogel platform promotes smooth muscle cell contractile phenotype maintenance.

Three dimensional (3D) bioprinting has been proposed as a method for fabricating tissue engineered small diameter vascular prostheses. This technique not only involves constructing the structural features to obtain a desired pattern but the morphology of the pattern may also be used to influence the behavior of seeded cells. Herein, we 3D bioprinted a gelatin hydrogel microchannel construct to promote and preserve the contractile phenotype of vascular smooth muscle cells (vSMCs), which is crucial for vasoresponsiveness. The microchanneled surface of a gelatin hydrogel facilitated vSMC attachment and an elongated alignment along the microchannel direction. The cells displayed distinct F-actin anisotropy in the direction of the channel. The vSMC contractile phenotype was confirmed by the positive detection of contractile marker gene proteins (α-smooth muscle actin (α-SMA) and smooth muscle-myosin heavy chain (SM-MHC)). Having demonstrated the effectiveness of the hydrogel channels bioprinted on a film, the bioprinting was applied radially to the surface of a 3D tubular construct by integrating a rotating mandrel into the 3D bioprinter. The hydrogel microchannels printed on the 3D tubular vascular construct also orientated the vSMCs and strongly promoted the contractile phenotype. Together, our study demonstrated that microchannels bioprinted using a transglutaminase crosslinked gelatin hydrogel, could successfully promote and preserve vSMC contractile phenotype. Furthermore, the hydrogel bioink could be retained on the surface of a rotating polymer tube to print radial cell guiding channels onto a vascular graft construct.

Contact guidance for cardiac tissue engineering using 3D bioprinted gelatin patterned hydrogel.

Here, we have developed a 3D bioprinted microchanneled gelatin hydrogel that promotes human mesenchymal stem cell (hMSC) myocardial commitment and supports native cardiomyocytes (CMs) contractile functionality. Firstly, we studied the effect of bioprinted microchanneled hydrogel on the alignment, elongation, and differentiation of hMSC. Notably, the cells displayed well defined F-actin anisotropy and elongated morphology on the microchanneled hydrogel, hence showing the effects of topographical control over cell behavior. Furthermore, the aligned stem cells showed myocardial lineage commitment, as detected using mature cardiac markers. The fluorescence-activated cell sorting analysis also confirmed a significant increase in the commitment towards myocardial tissue lineage. Moreover, seeded CMs were found to be more aligned and demonstrated synchronized beating on microchanneled hydrogel as compared to the unpatterned hydrogel. Overall, our study proved that microchanneled hydrogel scaffold produced by 3D bioprinting induces myocardial differentiation of stem cells as well as supports CMs growth and contractility. Applications of this approach may be beneficial for generating in vitro cardiac model systems to physiological and cardiotoxicity studies as well as in vivo generating custom designed cell impregnated constructs for tissue engineering and regenerative medicine applications.