Induced pluripotent stem cells (iPSCs) and their application to tissue engineering and disease modeling have great potential to change current medical practices. Current research is largely focused on devising efficient virus-free protocols to produce large numbers of iPSCs. Direct delivery of proteins obviates the risk of mutagenic insertion and enables more accurate control of the highly sensitive reprogramming process. However, cell-penetrating peptide methods currently provide reprogramming efficiencies that are too low for clinical use. The microfluidic delivery technology proposed has demonstrated its ability to deliver proteins at high efficiencies to human fibroblasts and it eliminates the need fo chemical modification or the use of exogenous compounds. Moreover, preliminary results indicate that the technique can be developed into a universal delivery method capable of delivering a range of macromolecules to different cell types underserved by current technologies. The current prototype is capable of delivering high throughput rates of 10,000-20,000 cells/s and can yield up to 1 million delivered cells per run. This combination of single-cell level control and macro-scale throughput places this device in a unique position relative to existing delivery methods.
Aim 1 : The mechanism of protein delivery and cell recovery will be investigated to better understand the system and direct its optimization. Preliminary results indicate macromolecular delivery occurs through a pore formation mechanism. To validate this hypothesis, model fluorescent macromolecules and proteins will be used in experiments designed to control against endocytosis and image membrane pores directly. Results will be used to develop a predictive model of the delivery system and conduct optimization studies to improve delivery efficiency, uniformity and cell viability. The design of future device generations will be guided by the gained mechanistic understanding and will aim to incorporate features such as coupling with electroporation. A streamlined version of the system will also be developed for use in collaborating laboratories.
Aim 2 : The intracellular delivery method will be optimized for protein-based reprogramming of fibroblasts to iPSCs. The robust delivery capabilities of the device will allow studies on the biological aspects of the reprogramming process itself, such as the optimal combination of transcription factors to produce maximum reprogramming efficiency and identification of the role of individual factor in the overall process Moreover, the device will be used to investigate potential improvements by combining other macromolecules, such as microRNA and mRNA, with protein-based reprogramming. In addition to reprogramming applications, such a high throughput microfluidic device platform capable of delivering a range of macromolecules with minimal cell death could enable unprecedented control over cellular function. Hence, in the future, it can be implemented in studies of disease mechanisms, identification of macromolecular therapeutic candidates, stem cell differentiation, and diagnostic applications with reporter cell lines.
We propose to investigate and optimize a recently developed a novel, microfluidic, intracellular delivery device capable of seemingly universal delivery of macromolecules (DNA, RNA, proteins, sugars, peptides) to different cell types. The systems robust capacity for protein delivery to human fibroblasts will be deployed in cell reprogramming studies to generate induced pluripotent stem (iPS) cells. Delineating the mechanism of action will enable one to predict and control delivery quantities with high accuracy, thus facilitating optimization studies to improve our understanding of reprogramming dynamics and thereby greatly increasing efficiencies.
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