CD34 expression does not correlate with immunophenotypic stem cell or progenitor content in human cord blood products

Abstract

Key Points The CD34+ compartment of human cord blood contains a range of HSPC immunophenotypes, among which the Lin−CD34+CD38+CD127+ CLP is rare. There is no correlation between the frequencies of CD34+ cells and immunophenotypic HSC in umbilical cord blood products.

A Kinetic Stem Cell Counting Analysis of the Specific Effects of Cell Culture Medium Growth Factors on Adipose-Derived Mesenchymal Stem Cells

“…These two long-standing challenges reflect the inherent cell heterogeneity of vertebrate animal tissues, including those of humans. The significant cell heterogeneity of both primary and processed human tissue cell preparations is well appreciated, and it has been considered as an important issue for attention in human cell therapy development [ 1 , 2 , 3 ]. However, its importance as a key factor making the quantification and expansion of tissue stem cells so challenging is not widely recognized.…”

“…Nearly all assays in current use for certifying the effectiveness of these products provide information about the effects on committed progenitor cells and differentiated cells as well as stem cells, because these non-stem cell types are often major cellular components in stem-cell-containing preparations, which are typical heterogenous cell populations [ 1 , 2 , 3 ]. This shortcoming applies to flow cytometry, colony-forming unit assays, and enzyme biomarker assays, because none of these methods quantify tissue stem cells specifically [ 4 , 5 , 6 ].…”

Quantification of the Culture Stability of Stem Cell Fractions from Oral-Derived, Human Mesenchymal Stem Cell Preparations: A Significant Step toward the Clinical Translation of Cell Therapies

“…To this end, we attempted a precise determination of the proportion of "true" stem cells within these mixed populations. Although it is widely acknowledged that primary human cell preparations are heterogeneous [32][33][34], to date, there have been only a few characterizations of the SCF within these cell preparations [13,15,16]. Undoubtedly, in many cases, it may be differences in the SCFs of these cell populations that lead to differences in the reported outcomes of their use in different experimental contexts and certainly in different clinical contexts.…”

Evaluation of the Precision of Kinetic Stem Cell (KSC) Counting for Specific Quantification of Human Mesenchymal Stem Cells in Heterogeneous Tissue Cell Preparations

“…Such a method would immediately better inform basic and clinical research investigations of important human and animal tissue stem cells by allowing investigators to relate the processes, functions, and factors under study to the number of stem cells present. A more accurate measure of the dosage of stem cells in approved HSC transplant treatments would address the current pervasive problem of the CD34 count being unreliable for predicting the outcome of umbilical cord blood transplants [5][6][7] as well as underestimating the dosage of HSCs in adult donor treatments, which results in a significant number of cases of poor graft failure [8][9][10]. These stem cell-specific dosage challenges in approved HSC transplant therapies are also certainly adversely affecting the effectiveness of other stem cell types in many current clinical trials [11][12][13].…”