CD34+ cell content of 126 341 cord blood units in the US inventory: implications for transplantation and banking

Abstract

CD34+ cell dose is critical for cord blood (CB) engraftment. However, the CD34+ content of the CB inventory in the United States is unknown. We examined the CD34+ cell content of 126 341 red blood cell–depleted US units banked from January 2007 to September 2017 with a total nucleated cell (TNC) count of ≥90 × 107 and a cryovolume of 24-55 mL. Median pre-cryopreservation TNC content was 127 × 107 (interquartile range [IQR], 108-156 × 107); CD34+ cell content was 44 × 105 (IQR, 29 to 67 × 105). The median CD34+:TNC ratio was 0.34%. TNC and CD34+ cell content correlation was weak (r = 0.24). Of 7125 units with TNCs of ≥210 × 107, only 47% had CD34+ content of ≥100 × 105. However, some units had high CD34+ content for a given TNC count. Only 4% of CB units were acceptable as single-unit grafts (TNCs, ≥2.5 × 107/kg; CD34+ cells, ≥1.5 × 105/kg) for 70-kg patients; 22% of units were adequate for 70-kg patients using lower dose criteria (TNCs, ≥1.5 × 107/kg; CD34+ cells, ≥1.0 × 105/kg) suitable for a double-unit graft. These findings highlight that units with the highest TNC dose may not have the highest CD34+ dose, units with unexpectedly high CD34+ content (a ratio of >1.0%) should be verified, and the US CB inventory of adequately sized single units for larger patients is small. They also support the ongoing use of double-unit grafts, a focus on banking high-dose units, and development of expansion technologies.

Comparison of electrostatic and mechanical cell sorting with limited starting material

“…The surface protein CD34 is an important marker of hematopoietic and vascular‐associated tissue, including hematopoietic stem and progenitor cells. The median ratio of CD34 + out of all nucleated cells in PB is 0.34% [26]. For the sorting of CD34 + cells only Tyto versus FACSAria sorting was evaluated.…”

BSHI guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation

“…The ASTCT guidelines for UCB unit selection (Politikos et al., 2020) mention expected median CD34 + /TNC ratio of 0.34% (range 0.23–0.48). It is recommended to question and verify cases where reported CD34 + cell dose is disproportionally high (Barker et al., 2019).…”

Cord blood beyond transplantation: can we use the experience to advance all cell therapies?

“…However, its most important limitation is the considerable variability of the progenitor cell numbers among CBUs with similar TNC counts. 20,25 As a result, high TNCs does not always 'predict' high progenitor cell numbers. 25 Flow-cytometric evaluation of the number of CD45 + and CD34 + cells and their viability is routinely performed.…”