The Different Approaches to Cell Sorting in the Cell Therapy Manufacturing Process

ThermoGenesis X-BACS technology

Cell and gene therapy is growing and new therapies are rapidly evolving , leading to an increase in the demand for efficient and effective cell therapy manufacturing. Each step in the process must be meticulously carried out in order to achieve the best possible results, increasing the likelihood of effectiveness for certain therapies. This begins with sorting specific cell types that are collected from patients or donors according to their properties to optimize their use in cell therapy manufacturing.


What is Cell Sorting?

Cell sorting is the separation of a mixture of cells based on their similar properties, including DNA, RNA, protein interaction, size and surface protein expression. This is an important consideration in the cell and gene therapy manufacturing process as certain components of cells can be used for different types of therapies. For example, cell engineering is used for treatments like CAR-T, while cell separation is necessary for bone marrow aspirate concentrate (BMAC) treatments. Cell sorting allows for a more in-depth characterization of cells with specific properties that can then be optimized for use in cell and gene therapy.


The Different Approaches to Cell Sorting

Cell separation methods take three main approaches – positive selection, negative selection and depletion.

  • Positive selection involves targeting the desired cell population with a removal mechanism (a molecule specific to a certain surface marker of the targeted cell), leaving any unwanted cells behind. Think of this as a magnet made specifically to attract the targeted cells only.
  • Negative selection is the opposite, where the unwanted cell types are labeled with antibodies or proteins that target specific cell markers and are removed, leaving the targeted (or wanted) cells behind.
  • Depletion is the third and simplest approach, in which a single cell type is removed from a sample. This is the same method used to remove large amounts of a contaminant, such as red blood cells (RBCs).


Cell Separation Methods

Within the three basic approaches to cell sorting are cell separation methods, such as Fluorescence Activated Cell Sorting (FACS) and Buoyancy Activated Cell Sorting (BACS)

In FACS, cells are labeled with fluorescent markers and then the sample is run through a flow cytometer device. During this process, cells are identified and sorted one by one based on the color of their markers. BACS, on the other hand, involves sorting cells with buoyant microbubbles. This selection process involves coating the microbubbles with molecules that attach themselves to targeted cells in order to lift them to the surface of the sample. Once there, they can be removed through aspiration or simply pipetting, leaving non-targeted cells behind.


ThermoGenesis X-BACS Cell Sorting Solution

ThermoGenesis’ proprietary X-BACS technology provides a cell sorting solution that addresses many unmet needs for cell and gene therapy such as being able to obtain high cell purity while being gentle on the cells, which minimizes the risk of diminishing cell viability. This novel technology offers researchers and medical professionals a way to select cells by combining the specificity of monoclonal antibodies and microbubbles.

The X-BACS technology is magnet-free, gentle on cells, and effective in obtaining viable, functional cells with reproducible results. 

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