A method of non destructive monitoring of biological processes in microfluidic tissue culture systems

Abstract

Microfluidic “organ-on-a-chip” devices have been developed with the aim to replicate human tissues in vitro. However, there is no option to quantitatively monitor biological processes that take place within the chip, over time. Destructive methods in order to analyze, tissue formation, gene expression, protein secretion etc. require the harvest of the “tissue” at a certain time point. Described herein are methods and compositions for non-destructive molecular imaging methods and systems in order to quantitatively monitor specific biological processes, over time, within the chip, without the need to harvest.

1 . A method of detecting cellular mineralization in a microfluidic device comprising:
 providing a microfluidic device comprising mesenchymal stem cells (MSCs), osteoblasts and/or osteocytes;   adding one or more labeling agents to the microfluidic device; and   detecting the labeling agent, wherein the labeling agent is capable of binding to cellular mineralization.   
     
     
         2 . The method of  claim 1 , wherein the microfluidic device further comprises one or more channels for loading of a control sample. 
     
     
         3 . The method of  claim 1 , wherein the one or more labeling agents comprise bisphosphonate imaging agents. 
     
     
         4 . The method of  claim 3 , wherein the bisphosphonate imaging agent comprises a pamidronate backbone with a fluorescent label. 
     
     
         5 . The method of  claim 3 , wherein the one or more labeling agents comprise a radiolabel. 
     
     
         6 . The method of  claim 5 , wherein the radiolabel comprises technetium-99m ([99mTc]-BPs), [18F]-Fluoride, 99mTc-Methyl diphosphonate (Tc-MDP), and/or 68Ga-Labeled (4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7,1 O-bis(carboxymethyl)-I,4, 7, I 0-tetraazacyclododec-1-yl)acetic acid (BPAMD) ([68Ga]BPAMD). 
     
     
         7 . The method of  claim 1 , wherein detecting the labeling agent comprises Micro CT, Micro SPECT, and/or PET imaging. 
     
     
         8 . The method of  claim 1 , wherein detecting the labeling agent further comprises comparison of the quantity of detected labeling agent with one or more control samples. 
     
     
         9 . The method of  claim 1 , comprising further culturing of mesenchymal stem cells (MSCs), osteoblasts, osteocytes, chondrocytes, tenocytes, fibroblasts, notochordal cells, and/or nucleus pulposus cells in the microfluidic device. 
     
     
         10 . The method of  claim 9 , comprising further detection of the labeling agent. 
     
     
         11 . A method of detecting secreted extracellular macromolecules in a microfluidic device comprising:
 providing a microfluidic device comprising stem cells;   applying one or more pulse sequences to the microfluidic device; and   detecting the pulse sequence signal intensity, wherein the pulse sequence signal intensity is capable of measuring one or more macromolecules secreted by the stem cells.   
     
     
         12 . The method of  claim 11 , wherein the stem cells are mesenchymal stem cells (MSCs). 
     
     
         13 . The method of  claim 11 , wherein the stem cells are pluripotent stem cells (pSCs). 
     
     
         14 . The method of  claim 13 , wherein the stem cells are induced pluripotent stem cells (iPSCs). 
     
     
         15 . The method of  claim 11 , wherein detecting the pulse sequence signal intensity comprises chemical exchange saturation transfer (CEST), pH measurement of T1 rho, magnetization transfer contrast (MTC), and/or magnetization exchange (MEX). 
     
     
         16 . The method of  claim 15 , wherein CEST detects a quantity of glycosaminoglycans (GAGs). 
     
     
         17 . The method of  claim 15 , wherein pH measurement of T1 rho detects a quantity of GAGs. 
     
     
         18 . The method of  claim 15 , wherein MTC detects a quantity of collagen. 
     
     
         19 . The method of  claim 15 , wherein MEX detects a quantity of collagen and/or osteoid. 
     
     
         20 . The method of  claim 11 , wherein the microfluidic device further comprises one or more channels for loading of a control sample. 
     
     
         21 . The method of  claim 11 , wherein detecting the pulse sequence signal intensity further comprises comparison of the quantity of detected pulse sequence signal intensity with one or more control samples. 
     
     
         22 . The method of  claim 11 , comprising further culturing of stem cells in the microfluidic device. 
     
     
         23 . The method of  claim 21 , comprising further detection of pulse sequence signal intensity.