Impact of modified gelatin on valvular microtissues

Abstract

A significant challenge in the field of tissue engineering is the biofabrication of three‐dimensional (3D) functional tissues with direct applications in organ‐on‐a‐chip systems and future organ engineering. Multicellular valvular microtissues can be used as building blocks for the formation of larger scale valvular macrotissues. Yet, for the controlled biofabrication of 3D macrotissues with predefined complex shapes, directed assembly of microtissues through bioprinting is needed. This study aimed to investigate if modified gelatin is an instructive material for valvular microtissues. Valvular microtissues were encapsulated in modified gelatin hydrogels and cross‐linked in the presence of a photoinitiator (Irgacure 2959 or VA‐086). Hydrogel properties were determined, and valvular interstitial cell functions like phenotype, proliferation, migration, mRNA expression of extracellular matrix (ECM) molecules, ECM deposition, and tissue fusion were characterized by histochemical stainings and RT‐qPCR. Encapsulated microtissues remained viable, produced heart valve‐related ECM components, and remained in a quiescent state. However, encapsulation induced some changes in ECM formation and gene expression. Encapsulated microtissues showed lower remodeling capacity and increased expression levels of Col I/V, elastin, hyaluronan, biglycan, decorin, and Sox9 compared with nonencapsulated microtissues. Furthermore, this study demonstrated that proliferation, migration, and tissue fusion was more pronounced in softer gels. In general, we evidenced that modified gelatin is an instructive material for physiologically relevant valvular microtissues and provided a proof of concept for the formation of larger valvular tissue by assembling microtissues at random in soft gels.

Hybrid Bioprinting of Chondrogenically Induced Human Mesenchymal Stem Cell Spheroids

“…Moreover, seeding adipose-derived MSC on gelMA resulted in a stronger accumulation of GAG compared to controls (Salamon et al, 2014). We also observed that gelMA encapsulation had a cumulative effect on GAG production within spheroids and Roosens et al (2019) reported the same trend when spheroids consisting of valvular interstitial cells were encapsulated. The constructs with lower stiffness resulted in a downregulation of collagen I and an increase in collagen II production.…”

Developments and Clinical Applications of Biomimetic Tissue Regeneration using 3D Bioprinting Technique

“…Applications include drug screening and toxicity testing, as well as the prospect of building a human-sized working in vitro heart in the future, as shown by the results [ 49 ]. The valvular microtissues comprising porcine valvular interstitial cells were encapsulated in a sort of modified gelatin as the instructional material to create large-scale 3D microtissue using UV-light crosslinking, as demonstrated by Roosens et al [ 50 ]. Using multicellular valvular microtissues as building blocks, we were able to generate the hypothesis that microchips may be assembled in such soft modified gelatin hydrogels using DLP or triphenylphosphine bioprinting technologies to construct functional, large-scale organoids.…”

Generating human skeletal myoblast spheroids for vascular myogenic tissue engineering

“…High circularity values reflect better spheroid integrity due to more cell-cell adhesion or the formation of endogenous ECM. The decision to add ascorbic acid was based on earlier research reporting that the compound, serving as an anti-oxidant, benefits spheroid cell survival and stimulates the production of collagen as an ECM component, thus keeping the microtissues integer [33,69,70]. This was reflected in the live/dead analysis displaying slightly more cell death in the condition without ascorbic acid added to the fusion medium.…”

“…Tissue-specific spheroids are generated using primary adult cells, cell lines, progenitor cells, cancerous cells and/or different types of stem cells. In prior work, primary articular chondrocytes were used as an adult cell source to generate monoculture chondrogenic spheroids [19], valvular interstitial cells were cultured for the generation of valvular spheroids in the context of studying valvular pathology [33] and hepatocytes were used for generating hepatocellular spheroids [34]. Several types of stem cells are used in tissue engineering based on their specific properties, such as proliferation and differentiation capacity and secretory properties modulating processes involving immune response and angiogenesis [21].…”