Microgels and microtissues for use in tissue engineering

Abstract

The present invention features microgels and microtissues for use in tissue engineering. Featured is a microencapsulation device for making microgels and/or microtissues via an emulsion technology. Also featured are methods of making higher ordered structures that mimic in vivo tissue structures. Methods of us are also featured.

1 . A population of microtissues produced by a method comprising injecting into a channel of a microfluidic device a first input stream comprising a solution of cells and a second input stream comprising a polymerizable hydrogel solution to form a combined aqueous stream;
 emulsifying the combined aqueous stream with an emulsion stream in a first region of the channel of the microfluidic device, to produce droplets comprising the cells in the polymerizable hydrogel,   mixing said droplets to disperse the cells in the polymerizable hydrogel in a second region of the channel comprising a serpentine section in the microfluidic device;   polymerizing the droplets comprising the cells dispersed in the polymerizable hydrogel to form the microtissues; and   collecting the microtissues from an outlet of the device,   such that the population of microtissues is made.   
     
     
         2 . The population of  claim 1 , wherein the hydrogel material is agarose, fibrin, or polyethylene hydrogel. 
     
     
         3 . A population of microtissues produced by a method comprising injecting into a channel of a microfluidic device a solution comprising pre-stabilized, micropatterned cell clusters and a polymerizable hydrogel solution, wherein the cell clusters comprise parenchymal cells and supporting nonparenchymal cells;
 emulsifying the solution of cell clusters and polymerizable hydrogel with an emulsion stream in a channel of the microfluidic device, to produce droplets comprising the cells in the polymerizable hydrogel,   polymerizing the droplets comprising the cells dispersed in the polymerizable hydrogel to form the microtissues, wherein polymerizing occurs during transport of the droplets, wherein transport occurs continuously; and   collecting the microtissues from an outlet of the device, such that the population of microtis sues is made.   
     
     
         4 . The population of  claim 3 , wherein the cell clusters comprise primary hepatocytes and stromal cells, for example, fibroblasts. 
     
     
         5 . The population of  claim 3 , wherein the cell clusters comprise hepatocytes selected from the group consisting of progenitor-derived hepatocytes, ES-derived hepatocytes, and induced pluripotent stem cell-derived (iPS-derived) hepatocytes, and stromal cells, for example, fibroblasts. 
     
     
         6 . The population of  claim 3 , wherein the cell clusters comprise cancer cells and stromal cells, for example, fibroblasts. 
     
     
         7 . The population of  claim 1 , wherein the prepolymerized hydrogel is a photopolymerizable hydrogel, for example, polyethylene glycol (PEG) hydrogel. 
     
     
         8 . The population of  claim 1 , wherein the hydrogel is functionalized with one or more affinity biomolecules facilitating higher ordered assembly of the said microtissues. 
     
     
         9 . The population of  claim 8 , wherein the biomolecule is streptavidin, or a cell adhesive peptide, for example, the biomolecule is RGDS peptide. 
     
     
         10 . The population of  claim 3 , wherein the droplets or microtissues are about 50 to about 250 μM in diameter. 
     
     
         11 . The population of  claim 1 , wherein the droplets of microtissues are about 20 to about 150 μM in diameter. 
     
     
         12 . The population of  claim 1 , wherein the droplets comprise about 1 to about 50 cells. 
     
     
         13 . The population of  claim 1 , wherein each microtissue comprises about 2 to about 20 cells or wherein each microtissue comprises about 5 to about 10 cells. 
     
     
         14 . A method of making a construct, comprising assembling all or a portion of the population of microtissues of  claim 1  into a higher ordered structure. 
     
     
         15 . The method of  claim 14 , wherein the microtissues comprise an encoding biomolecule or affinity ligand and a substrate is patterned with a templating biomolecule or ligand, such that when the substrate is contacted with the population of microtissues, the microtissues are assembled in the pattern of the substrate. 
     
     
         16 . The method of  claim 15 , wherein the encoding and templating biomolecules are complementary DNAs or complementary affinity ligands. 
     
     
         17 . The method of  claim 14 , wherein the microtissues are assembled by physical means. 
     
     
         18 . A construct produced by the method of  claim 15 . 
     
     
         19 . An assay system featuring the construct of  claim 18 . 
     
     
         20 . The assay system of  claim 19 , which is a metabolic assay system or a toxicology assay system. 
     
     
         21 . The assay system of  claim 20 , which is a screening assay system for anti-tumorogenic compounds. 
     
     
         22 . A microencapsulation device comprising one or more injection ports in contact with a microchannel comprised therein, said injection ports for introducing one or more aqueous solutions, a droplet generating nozzle into which said solutions flow, an emulsion stream in contact with said droplet generating nozzle, a mixer section for dispersing components of droplets, a polymerizing section, and an outlet. 
     
     
         23 . A microencapsulation device as depicted in  FIG. 2 .