Periodic Reporting for period 1 - PTOoC (Plug-n-Play Tool-kit of Organ-on-Chips)
Période du rapport: 2019-10-11 au 2021-10-10
Pharmaceutical drugs are a critical aspect of the current health-care practices. The effectiveness of a given treatment protocol is highly dependent on efficacy of the drug being administered. The need for effective and high-quality health-care drives the pharmaceutical industry to discover and develop new drug molecules. Of late, there has been a staggering rise in the cost of bringing new drugs to the market. The use of animal based drug-testing protocols is one of the major reasons for this increasing developmental expenditure. In the initial phases, drugs are tested by administering them to animals (like mice, rabbits etc). Often drugs which clear the initial testing fail to demonstrate efficacy or prove to be harmful, when tested on humans at a later phase of testing. The lack of predictive insights early-on in the development cycle leads to failure of drug candidates in human clinical trials. At which point, the company would have typically invested years of time and billions of dollars in R&D costs. Due to the inherent differences in physiology (at a systemic-level) between animals and humans, animal based testing does not provide essential insights on whether a drug molecule would clear human clinical trials. The demand for testing systems with high physiological similarity to humans, while being cost-effective has led to the development of Organ-on-Chip (OoC) or Micro-Physiological Systems (MPS). Human physiology is incredibly complex at the systemic level and is different in many nuanced ways from the animals that are used to test drugs. Organ-on-chips (Oocs) efficiently mimic various aspects of the environment, in which cells are present within the human body. Evaluation of cellular response (to drugs) using OoCs would provide better predictive insights and reduce R&D expenses by identifying inviable drug molecules early-on.
By leveraging advances from micro-scale fabrication, researchers have been able to demonstrate organ-level physiological response for the human heart, lung, liver, gut, kidney, skin, vasculature. OoCs have begun to make their way into the real-world, with the emergence of several start-ups trying to commercialize them. However, OoCs have yet to cross certain key barriers, for them to become the gold-standard method for drug testing. The current state-of-the-art in OoCs suffer from low standardization level, low through-put work-flows in comparison to their conventional cell culture-based counterparts. Further, the functional scaling of organ sizes and vascular flow warrants a major design constraint in the development of OoCs.
The current project proposes to develop an modular approach to design and fabricate OoC systems. Such an approach will enable quick design and rapid prototyping of OoC systems, while instilling a high-level of standardization in the domain. Specifically, the main objective of the project was to design and develop a library of inter-lockable components, which can be used to construct any given organ-on-chip at the required physiological/functional scale. Each part of the library would serve to enable a certain physicochemical stimulus/structure warranting its use in the design of a specific type of organ-on-chip.
By leveraging advances from micro-scale fabrication, researchers have been able to demonstrate organ-level physiological response for the human heart, lung, liver, gut, kidney, skin, vasculature. OoCs have begun to make their way into the real-world, with the emergence of several start-ups trying to commercialize them. However, OoCs have yet to cross certain key barriers, for them to become the gold-standard method for drug testing. The current state-of-the-art in OoCs suffer from low standardization level, low through-put work-flows in comparison to their conventional cell culture-based counterparts. Further, the functional scaling of organ sizes and vascular flow warrants a major design constraint in the development of OoCs.
The current project proposes to develop an modular approach to design and fabricate OoC systems. Such an approach will enable quick design and rapid prototyping of OoC systems, while instilling a high-level of standardization in the domain. Specifically, the main objective of the project was to design and develop a library of inter-lockable components, which can be used to construct any given organ-on-chip at the required physiological/functional scale. Each part of the library would serve to enable a certain physicochemical stimulus/structure warranting its use in the design of a specific type of organ-on-chip.
Amongst the required physiological cues, mechanical strain occurs most often and is required for emulation of cell/tissue micro-environments of several different body organs, including heart, lung, skin, blood vessels and muscles etc. Within the proposed library of parts, a plug-in tool for facilitating mechanical stretching of cells was designed. The tool is designed to tightly lock itself onto a conventional cell culture insert. The part consists of a pressure cavity, which is sealed on the top side with a flexible membrane. When the cavity is pressurized, the flexible membrane is deformed. The top flexible membrane remains directly in contact with the culture membrane of the cell culture insert. When the chamber is pressurized the deformed seal pushes upwards (ON STATE). As the cell culture membrane remains in direct contact with the flexible membrane of the part, the deformation of the top seal results in an upward push acting on the cell culture membrane in the centre. This central upward push will allow/enable the membrane to stretch uniformly around the centre.
As per the proposed schematic, the part was modelled in a computer-aided design (CAD) software. The inner diameter of the part is approximately 27.5 mm, which closely fits the diameter of a typical cell culture insert. The overall height of the part is about 10 mm, the inner height is about 6 mm, so that the insert is placed at about the same from the bottom of the well plate. This ensures a very small deviation from conventional format and increases the required culture medium volume, only by a small amount. The designed part was fabricated by milling plastic using a desktop milling machine (Bantam tools). The fabricated part is shown in figure 2.
As per the proposed schematic, the part was modelled in a computer-aided design (CAD) software. The inner diameter of the part is approximately 27.5 mm, which closely fits the diameter of a typical cell culture insert. The overall height of the part is about 10 mm, the inner height is about 6 mm, so that the insert is placed at about the same from the bottom of the well plate. This ensures a very small deviation from conventional format and increases the required culture medium volume, only by a small amount. The designed part was fabricated by milling plastic using a desktop milling machine (Bantam tools). The fabricated part is shown in figure 2.
As demonstrated, the tool can be used to very easily induce deformation in the bottom of a given cell culture well. The deformation of the well would get easily translated to cell seeded on the bottom of the well plate. The precise quantitative stress applied on the cells is a critical experimental parameter, when trying to mimic the in-vivo cell micro-environment. Using the developed plug-in tool, it would be possible to very finely control stress applied on cells seeded on the cell culture well. The developed plug-in tool demonstrates a great potential for standardization in the OoCs domain. The availability of such a parts library would allow standardized experimentation across different teams, leading to the potential evolution of universally accepted methods, protocols for drug-testing. Such approaches would eliminate the need for animal-model based drug testing and consequently bring-down the cost of pharmaceutical drug development. Overall, the achieved milestones demonstrate the elegance of employing a simplified design approach to improve standardization, lower costs and thereby make advanced experimental techniques easily accessible to the wider research community.