Design and biofabrication of a leaf-inspired vascularized cell-delivery device

We designed and biofabricated a channeled construct as a possible cell-delivery device that can be endothelialized to overcome size limitations due to oxygen diffusion. The channeled device mimicking a leaf was designed using computer-aided design software, with fluid flow through the channels visualized using simulation studies. The device was fabricated either by form casting using a custom 3D-printed plastic mold or by 3D-bioprinting using Pluronic F-127 as sacrificial ink to print the channels. The actual leaf was cast or bioprinted using hydrogel made from a mixture of tunicate cellulose nanofibers and alginate that was cross-linked in calcium chloride solution to allow a stable device. The resulting device was a 20 7 8 7 3 mm or 35 7 18 7 3 mm (length 7 width 7 height) leaf with one main channel connected to several side channels. Surface modification using periodate oxidation, followed by laminin bioconjugation, was performed to enhance endothelial cell adhesion in the channels. We subsequently used human umbilical vein endothelial cells to demonstrate the efficacy of the device for promoting endothelialization. These results indicated that the biofabricated device has great potential for use in tissue-engineering for various applications associated with the need of perfusable vasculature

Autologous endothelialisation by the stromal vascular fraction on laminin-bioconjugated nanocellulose-alginate scaffolds

Establishing a vascular network in biofabricated tissue grafts is essential for ensuring graft survival. Such networks are dependent on the ability of the scaffold material to facilitate endothelial cell adhesion; however, the clinical translation potential of tissue-engineered scaffolds is hindered by the lack of available autologous sources of vascular cells. Here, we present a novel approach to achieving autologous endothelialisation in nanocellulose-based scaffolds by using adipose tissue-derived vascular cells on nanocellulose-based scaffolds. We used sodium periodate-mediated bioconjugation to covalently bind laminin to the scaffold surface and isolated the stromal vascular fraction and endothelial progenitor cells (EPCs; CD31+CD45−) from human lipoaspirate. Additionally, we assessed the adhesive capacity of scaffold bioconjugation in vitro using both adipose tissue-derived cell populations and human umbilical vein endothelial cells. The results showed that the bioconjugated scaffold exhibited remarkably higher cell viability and scaffold surface coverage by adhesion regardless of cell type, whereas control groups comprising cells on non-bioconjugated scaffolds exhibited minimal cell adhesion across all cell types. Furthermore, on culture day 3, EPCs seeded on laminin-bioconjugated scaffolds showed positive immunofluorescence staining for the endothelial markers CD31 and CD34, suggesting that the scaffolds promoted progenitor differentiation into mature endothelial cells. These findings present a possible strategy for generating autologous vasculature and thereby increase the clinical relevance of 3D-bioprinted nanocellulose-based constructs