Wharton’s Jelly Mesenchymal Stromal Cells Support the Expansion of Cord Blood–derived CD34⁺ Cells Mimicking a Hematopoietic Niche in a Direct Cell–cell Contact Culture System

Abstract

Wharton's jelly mesenchymal stromal cells (WJ-MSCs) have been recently exploited as a feeder layer in coculture systems to expand umbilical cord blood-hematopoietic stem/progenitor cells (UCB-HSPCs). Here, we investigated the role of WJ-MSCs in supporting ex vivo UCB-HSPC expansion either when cultured in direct contact (DC) with WJ-MSCs or separated by a transwell system or in the presence of WJ-MSC-conditioned medium. We found, in short-term culture, a greater degree of expansion of UCB-CD34 cells in a DC system (15.7 ± 4.1-fold increase) with respect to the other conditions. Moreover, in DC, we evidenced two different CD34 cell populations (one floating and one adherent to WJ-MSCs) with different phenotypic and functional characteristics. Both multipotent CD34/CD38 and lineage-committed CD34/CD38 hematopoietic progenitors were expanded in a DC system. The former were significantly more represented in the adherent cell fraction than in the floating one (18.7 ± 11.2% vs. 9.7 ± 7.9% over the total CD34 cells). Short-term colony forming unit (CFU) assays showed that HSPCs adherent to the stromal layer were able to generate a higher frequency of immature colonies (CFU-granulocyte/macrophage and burst-forming unit erythroid/large colonies) with respect to the floating cells. In the attempt to identify molecules that may play a role in supporting the observed ex vivo HSPC growth, we performed secretome analyses. We found a number of proteins involved in the HSPC homing, self-renewal, and differentiation in all tested conditions. It is important to note that a set of sixteen proteins, which are only in part reported to be expressed in any hematopoietic niche, were exclusively found in the DC system secretome. In conclusion, WJ-MSCs allowed a significant ex vivo expansion of multipotent as well as committed HSPCs. This may be relevant for future clinical applications.

CD34 cells in somatic, regenerative and cancer stem cells: Developmental biology, cell therapy, and omics big data perspective

“…Hence, it is possible that during early development, the CD34 + cells might have migrated to various lineages harbor the intrinsic property for supporting angiogenesis in all tissues. Coculture of the CD34‐umbilical cord (UC) mesenchymal stem cells with CD34+ UC blood‐derived HSPCs have been demonstrated to enhance the expansion of the latter . Secretome analysis of the coculture media led to the identification of several involved in the HSPC maintenance and development.…”

Autologous Cord Blood in Children with Cerebral Palsy: A Review

“…Its remodeling enzymes was also studied in multipotent mesenchymal stromal cells (MSCs) from human adipose tissue [144]. In a direct cell-cell contact culture system, WJ-MSCs enhanced the expansion of CB-CD34+ cells [145]. Further investigations in this field are required.…”

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“…In an attempt to overcome this hurdle, several approaches have used hematopoietic stem cells (HSCs) isolated from either umbilical cord blood (UCB), bone marrow (BM) or PB as potential resources to generate higher production of reticulocytes in-vitro for parasite invasion 26,34,39,40 . The culture systems include the application of specific cytokines and either co-culture the HSCs with feeder cells (i.e., human mesenchymal stem cells) 41,42,43,44 to mimic the medullar microenvironment or without feeder cells 43,45 . With sequential addition of specific growth factors (GFs) such as stem cell factors (SCF), interleukin-3 (IL-3), hydrocortisone and erythropoietin (EPO) in CD34 + HSC differentiation medium, the parasite culture could be maintained for a longer period in the presence of reticulocytes derived from CD34 + HSCs 34,39 .…”