Development and Clinical Implementation of Ultra-high Speed Cell Sorting for Regenerative Medicine Applications
Both adult and embryonic stem cells hold profound therapeutic promise. However, a major bottleneck thwarting the effective use of both adult and embryonic stem cells in the clinic is the lack of rapid and accurate flow-based sorting strategies that are compatible with Good Manufacturing Practices (GMP). With embryonic stem cells, the current inability to rapidly and cleanly sort out and eliminate the primitive, pluripotent cells that remain in differentiated cultures is a serious hurdle. These cells can cause the formation of encapsulated tumors, called teratomas, as well as other possible adverse consequences when used therapeutically. Until these primitive, pluripotent cells can be removed, it will remain difficult to obtain regulatory approval for the use of human embryonic stem cells (hESC) in clinical trials. Current proposed hESC clinical protocols consist of cellular products differentiated from hESCs without the use of sorting to definitively exclude primitive, pluripotent hESC that could potentially form teratomas or undergo uncontrolled differentiation in vivo. Trials done without appropriate separation strategies could be very detrimental to the field.
Flow-based cell sorters that use fluorescent cellular markers have been in use for many years in research applications. While excellent research tools, these sorters are ill-suited for use in a clinical setting. In particular, they rely on aerosolization of the patient sample, resulting in the risk of sample contamination and potential safety risks to the operator of the machine. While they have been used in clinical trials, they are complex, difficult to sterilize between patients, and in the context of cellular therapy, relatively slow. Therefore, as trials progress it would be beneficial to have sorters that are improved upon in their ease of use, sort speed and incorporating a closed system which can readily be exchanged for single patient use.
The goal of the proposed research is to eliminate this bottleneck by providing an ultra-high speed cell sorter and appropriate methodology for use in clinical applications. The key features of such a system are: 1) speed and yield sufficient to process clinically relevant cell populations, 2) the ability to provide a very high purity sort, and 3) the ability to perform this sorting in a completely sterile, disposable fluid path that can be manufactured using GMP-compliant practices. The system makes use of micro-electromechanical systems (MEMS) technology to fabricate a silicon chip with integrated sorter mechanisms. This chip is then assembled into a sterile and disposable fluidic system that includes blood bags and appropriate tubing to connect the bags and chip. Sorting of adult stem cell samples has been demonstrated, and the system is now at a beta test level. However, significant development and testing is necessary to progress to demonstrated performance of fully functional clinical machines.
From the California Institute for Regenerative Medicine website ,
“In theory, there’s no disease that is exempt from a possible treatment that comes out of stem cell research. Given that researchers may be able to study all cell types via embryonic stem cells, they have the potential to make breakthroughs in any disease. …The promise of embryonic stem cells is that they can form any type of cell in the body. The trouble is that when implanted into an animal they do just that, forming all tissue types in the form of tumors called teratomas. …Even when researchers have learned to mature cells into a single cell type, getting those cells pure enough to eliminate the risk of remaining immature cells forming teratomas has been extremely difficult.”
This project is the development of a faster, more efficient cell sorting system that will remove the bottleneck of stem cell purification. Besides enabling advances in hESC research and clinical development, this will also accelerate the development and commercialization of adult stem cell therapies. The proposed project dramatically benefits the state of California in 3 ways:
Health of Californians: Because removal of this bottleneck may result in a profound positive impact on numerous envisioned therapies, quantification of that impact can be difficult. Consider just one application: cell therapies for Peripheral Vascular Disease (PVD). PVD, also known as arteriosclerosis of the extremities, is a disease of the blood vessels characterized by hardening of the arteries that supply the legs and feet. It is estimated that 1 to 1.4 million people suffer from PVD in California alone. The size of the affected populations poses a real issue in delivering therapies, especially if they depend on conventional cell sorting. The system that will arise from this project permits ready scale-up so these therapies can actually be delivered to Californians.
Pace of Medical Research: The inability to purify stem cell populations has seriously hindered the fundamental research of many disease states and the development of clinical treatments derived from that research. By providing a means of stem cell purification, researchers will be able to focus their attention on this much needed basic research.
Economic benefit: The overriding economic benefit to the state is in fact in the form of improved health for Californians. This directly translates into reduced medical expenses that result from secondary care of many diseases. The proposed research also results in the development of a cell isolation technology that relies on the manufacture of machines and disposable cell therapy kits. A substantial portion of these will be manufactured in California, thereby creating additional jobs and tax revenue. Furthermore, the availability of a technology that enables readily scalable manufacture of clinical grade cell therapies will encourage the development of companies that make cellular products to treat Californians.