Stem cell separation: A bottleneck in stem cell therapy

Abstract

The substantial progress in embryonic stem cell (ESC) research could lead to new possibilities in the treatment of various diseases. Currently, applications of ESC for cell therapy are impeded by the presence of potentially teratoma-forming undifferentiated ESC. Thus, a selective and quantitative removal of undifferentiated ESC from a pool of differentiated and undifferentiated cells is essential before cell therapy. We evaluated the highly selective magnetic activated cell sorting (MACS) method for the quantitative removal of undifferentiated ESC. We found that the clearance rates for undifferentiated ESC decreased with decreasing amount of undifferentiated ESC in the cell pool. Using a simplified model calculation we could predict that, assuming an initial purity of 60%, an estimated 31 steps are required to achieve less than 10(-1) cell per 10(9) cells. Thus, a log clearance rate of 10, which would be necessary for a therapeutically application, is hard to achieve. Our work clearly indicates that the current MACS technology is insufficient to meet the purification needs for cell therapy.

Technological developments in dielectrophoresis and its path to commercialization

“…However, the methods also have advantages; whilst not as fast as centrifugation, MACS can process up to one billion cells in an hour, whilst FACS is limited to a few tens of millions of cells over 2-3 hours including sample preparation time and setup, whilst FACS in particular is also good for pinpointing very rare cells through the use of multiple dyes; MACS is ultimately limited to identifying cells by surface markers alone. Consequently, these methods are of questionable application for cell therapeutic applications [12].…”

Current strategies and challenges for the purification of stem cells

“…Scale-up for microdevices remains limited to the integration of several identical units in parallel configuration, therefore, the amount of processed cells is not sufficient to satisfy the requirements of a therapeutic dose of 10 7 -10 9 stem cells per patient. 51 In this sense, the potential application of this technology is in the diagnosis field. Whereas, antibody conjugated flat matrices or columns can be scaled-up by increasing the surface area to promote the interaction of the target cells with the coupling antibody, improving loading capacity and facilitating removal of the contaminants.…”

A Quality-by-Design Approach to Risk Reduction and Optimization for Human Embryonic Stem Cell Cryopreservation Processes

“…Resultant statistically 3 uncontrolled or high intrinsic variation processes are very challenging to characterise at a level expected for manufacturing and have led to production processes with poor control and significant endpoint quality testing and wastage. This results in high risk product manufacture from a regulatory and economic perspective, a situation exacerbated by the restricted ability to purify the end product (11,12) which increases the criticality of the entire bioprocess to the integrity of the end-product relative to molecular therapies (13).…”