Vascularized organoid engineered by modular assembly enables blood perfusion

Abstract

Tissue engineering is one approach to address the donor-organ shortage, but to attain clinically significant viable cell densities in thick tissues, laboratory-constructed tissues must have an internal vascular supply. We have adopted a biomimetic approach and assembled microscale modular components, consisting of submillimeter-sized collagen gel rods seeded with endothelial cells (ECs) into a (micro)vascularized tissue; in some prototypes the gel contained HepG2 cells to illustrate the possibilities. The EC-covered modules then were assembled into a larger tube and perfused with medium or whole blood. The interstitial spaces among the modules formed interconnected channels that enabled this perfusion. Viable cell densities were high, within an order of magnitude of cell densities within tissues, and the percolating nature of the flow through the construct was evident in microcomputed tomography and Doppler ultrasound measurements. Most importantly, the ECs retained their nonthrombogenic phenotype and delayed clotting times and inhibited the loss of platelets associated with perfusion of whole blood through the construct. Unlike the conventional scaffold and cell-seeding paradigm of other tissue-engineering approaches, this modular construct has the potential to be scalable, uniform, and perfusable with whole blood, circumventing the limitations of other approaches.collagen gel modules ͉ endothelial cells ͉ tissue engineering

Collagen- vs. Gelatine-Based Biomaterials and Their Biocompatibility: Review and Perspectives

“…A nonexhaustive overview of the most recent publications, subdivided by application, for either collagen or gelatine alone or in a combination of other biopolymers is summarized in Table 2 which clearly indicates that gelatine has a wider-application range within the field of both soft and hard-tissue engineering. (Spira et al, 2004) skin replacement artificial skin dermis (Harriger et al, 1998) skin tissue engineering Tangsadthakun et al, 2006) artificial skin (Choi et al, 1999;Lee et al, 2003) soft tissue adhesives (McDermott et al, 2004) Surgery hemostatic agent (Cameron, 1978;Browder & Litwin, 1986) plasma expander suture wound dressing and repair (Rao, 1995) skin replacement (artificial skin) nerve repair and conduits blood vessel prostheses (Auger et al, 1998;McGuigan et al, 2006, Amiel et al, 2006 small intestine ( Chiu et al, 2009) liver -chitosan/gelatine scaffold (Jiankang et al, 2007) wound dressing (Tucci & Ricotti, 2001) nerve regenerationchitosan/gelatin scaffolds (Chiono et al, 2008) blod vesels ( Mironov et al, 2005) Orthopaedic born, tendon and ligament repair cartilage reconstruction -collagen (Stone, 1997), composite of collagen type II/chondroitin/hyaluronan (Jančar et al, 2007) articular cartilagecollagen/chitosan (Yan et al, 2010) bone substitutegelatine/hydroxyapatite (Chang et al, 2007) hard tissue regenerationgelatine/hydroxyapatite ( Kim et al, 2005) cartilage (Lien et al, 2010) cartilage defects regenerationchitosan/ gelatine (Guo et al, 2006), ceramic/ gelatine bone substitutegelatine/tricalcium phosphate (Yao et al, 2005) Ophthalmology corneal graft (Lass et al, 1986) vitreous implants artificial tears (Kaufman et al, 1994) tape and retinal reattachment contact lenses eye disease treatment (http.....) ocu...…”

Chimeric Vessel Tissue Engineering Driven by Endothelialized Modules in Immunosuppressed Sprague-Dawley Rats

“…3 Functional cells are embedded in submillimeter-sized collagen rods and the outside surface is coated with endothelial cells (EC). These units are referred to as modules and form microtissues when there are cells embedded in them.…”

“…This is contrary to the original premise associated with modular tissue engineering. 3 It will be interesting to explore whether the addition of supporting cell types or cytoprotective genes further enhances the vascularization capacity of this model. Studies with supporting mesenchymal stem cells are underway.…”

Directed assembly of cell-laden microgels for fabrication of 3D tissue constructs

“…To date, bottom-up assembly of microgels has been achieved by random packing of cell-laden microgels (14), by using photolithography to build layers of microgels with controlled alignment (15), or by physical manipulation of individual cell-laden microgels (16). However, a number of potential limitations exist with these approaches.…”