Abstract
Mesenchymal stem cells (MSCs) are of great interest in cell therapies
due to their immunomodulatory properties and other effects they have on
recipients after autologous or allogeneic transplantation. In the
majority of clinical applications, a high number of MSCs is required;
for this reason, isolated MSCs have to be expanded in the cell culture
until the desired number is reached. Determining the MSC count from
different tissue origins preceding cell expansion is not widely
implemented. Phenotyping using flow cytometry and MSCs enumeration is
usually performed only during or after their expansion. Counting freshly
isolated cells is challenging due to their rareness and heterogeneity.
Heterogeneity is noticeable among donors, tissues, and cell
subpopulations. The identification of MSCs from different tissues is
also complex because there is no consensus on the uniform cell surface
marker panel. There are also differences in the concentration of cells
which may be influenced by donor age, health status, isolation methods,
and various other factors. As MSC applicability is continuously growing
and developing, there is a need to implement and standardise counting
methods for freshly isolated MSCs. With the introduction of a uniform
procedure to count MSCs right after tissue harvest, we could predict the
number of passages needed for cell expansion and reduce overall cell
manufacturing costs. For new methodologies, where uncultured cells are
used in therapy with what are referred to as one-step procedures,
determining the number of freshly isolated MSCs is even more important