Clinical Studies of Ex Vivo Expansion to Accelerate Engraftment After Umbilical Cord Blood Transplantation: A Systematic Review.
Level 4 - case-series / case-control
Systematic review of predominantly non-randomized, early-phase, historically controlled clinical studies
PubMed 28087163 · doi:10.1016/j.tmrv.2016.12.004
What was done
A systematic review was conducted to assess clinical outcomes of ex vivo expansion of umbilical cord blood (UCB) prior to hematopoietic cell transplantation. The review evaluated 15 published clinical studies encompassing 349 transplanted patients and 13 registered clinical trials. Strategies examined included co-infusion of an expanded unit with an unmanipulated unit (8 studies), fractional expansion of 12% to 60% of a single unit (5 studies), and infusion of a single expanded unit (2 studies), utilizing approaches such as cytokine cocktails, mesenchymal stromal cell (MSC) co-culture, and small molecules (e.g., nicotinamide, StemRegenin-1).
What was found
Higher total cell dose was closely associated with faster neutrophil recovery. Compared with historical controls, neutrophil engraftment was significantly accelerated in studies employing small molecules or MSC co-culture, with some showing statistically improved platelet recovery. Studies using nicotinamide and StemRegenin-1 achieved long-term chimerism from the expanded unit. However, no specific quantitative effect sizes or p-values were provided in the abstract, and no strategy demonstrated statistically significant improvements in overall survival or other key transplant-related clinical outcomes.
Why it matters
Ex vivo expansion successfully overcomes the cell-dose bottleneck of umbilical cord blood to shorten the dangerous post-transplant cytopenic window. However, faster engraftment has not yet translated into proven survival benefits in completed clinical studies.
Limits
The included studies were predominantly early-phase, non-randomized series compared against historical controls rather than concurrent randomized comparators. Total patient numbers across studies were modest (349 patients across 15 studies), and quantitative data for engraftment times, infection rates, graft-versus-host disease, and survival were not detailed in the abstract.
Cited by
- supports A standard cord blood unit typically does not contain enough stem cells to successfully treat an adult bone marrow transplant recipient.