In 1994, it was found that mechanical properties of airway smooth muscle (ASM) preparations from healthy and asthmatic patients differed significantly. In particular, it was demonstrated that maximum contractility for healthy ASM was ~11%, whereas asthmatic ASM allowed up to ~31% contraction. This led to the hypothesis about an excessive bronchoconstriction in asthma1. Due to hyperplasia and hypertrophy, a significant increase in ASM mass is observed in asthmatic airway wall, whereas the muscle is thought not to be stronger2–4. It was further suggested that due to the above pathology, the ASM contraction might occur faster rather than stronger and its relaxation might be impaired5. The increase of ASM mass was also found in children without any signs of eosinophilic inflammation6, suggesting that the increased mass of ASM might be the cause rather than the consequence of asthmatic disease. The ability of ASM cells (ASMs), i.e., bronchial smooth muscle cells (BSMCs), to secrete battery of cytokines prompts that the local and also systemic (in both autocrine and paracrine fashion) airway inflammation can be achieved without inflammatory cells. Finally, it is believed that ASM hyper-contractility is an intrinsic abnormality seen in asthmatic airways7,8 and this process was mathematically modeled9. The above hypotheses and models, however, have never been directly and decisively tested due to absence of appropriate ASM spheroid contraction sensor platform. ASMs play crucial role in the following processes: (i) regulation of the airway tone through a contraction vs. dilation balance10; and (ii) excessive airway narrowing.
In this Solution, NextGenRnD reports novel platform technology that should enable direct measurement of pressure generated by ASM spheroid during contraction in high throughput format (healthy vs. asthmatic ASM spheroids). This platform should allow quantitative and real-time analysis of contraction and dilation of ASM spheroids in non-invasive manner.
To monitor and to measure contraction (compression) of ASM spheroid, it is required to embed a specialized compressible microsphere into the ASM spheroid core. This microsphere will serve as the ASM spheroid contraction sensor. Imaging the microsphere by confocal microscopy will provide values of variables required for solving the equation used for obtaining pressure value (in pascals). The equation used for pressure monitoring during the compression of the microsphere by the ASM spheroid is included in the Solution.
The microsphere has the following properties: (1) it has a hydrogel shell and a liquid core; (2) its exact size and shell thickness can be controlled directly; (3) its shell is based on a material, which is FDA-approved for clinical use; (4) it is at least 40% compressible; (5) it is capable of recovering its initial shape and size instantaneously (<1 second) without residual deformation; and (6) its shell can be imaged at depths exceeding 300 μm. The cost of 1,000 microspheres is approximately $1. Tens of millions of microspheres can be produced per day.
The ASM spheroid has the following properties: (1) it is formed in a two-step process, which requires several days; (2) it is composed of human ASMs and one additional type of human primary cells; and (3) its design is based on a proven approach for the assembly of most powerfully contracting spheroids described to date.
The Solution also contains: experimental steps required for the ASM spheroid contraction sensor platform validation, experimental plan, and feasibility analysis. In addition, high-throughput approaches for identification of novel potential targets for asthma treatment are described (both biological and chemical).
The ASM spheroid contraction sensor platform should assist in revealing the following major functional differences between healthy and asthmatic ASMs: overall microtissue structural organization; contraction pressure; and contraction/relaxation rapidity.