Abstract
BackgroundCord blood (CB) is a promising source for hematopoietic stem cell transplantations. The limitation of cell dose associated with this source has prompted the ex vivo expansion of hematopoietic stem and progenitor cells (HSPCs). However, the expansion procedure is known to exhaust the stem cell pool causing cellular defects that promote apoptosis and disrupt homing to the bone marrow. The role of apoptotic machinery in the regulation of stem cell compartment has been speculated in mouse hematopoietic and embryonic systems. We have consistently observed an increase in apoptosis in the cord blood derived CD34+ cells cultured with cytokines compared to their freshly isolated counterpart. The present study was undertaken to assess whether pharmacological inhibition of apoptosis could improve the outcome of expansion.Methodology/Principal FindingsCB CD34+ cells were expanded with cytokines in the presence or absence of cell permeable inhibitors of caspases and calpains; zVADfmk and zLLYfmk respectively. A novel role of apoptotic protease inhibitors was observed in increasing the CD34+ cell content of the graft during ex vivo expansion. This was further reflected in improved in vitro functional aspects of the HSPCs; a higher clonogenicity and long term culture initiating potential. These cells sustained superior long term engraftment and an efficient regeneration of major lympho-myeloid lineages in the bone marrow of NOD/SCID mouse compared to the cells expanded with growth factors alone.Conclusion/SignificanceOur data show that, use of either zVADfmk or zLLYfmk in the culture medium improves expansion of CD34+ cells. The strategy protects stem cell pool and committed progenitors, and improves their in vitro functionality and in vivo engraftment. This observation may complement the existing protocols used in the manipulation of hematopoietic cells for therapeutic purposes. These findings may have an impact in the CB transplant procedures involving a combined infusion of unmanipulated and expanded grafts.
Highlights
Cord Blood serves as an alternate source of hematopoietic stem cells for patients with malignant and non malignant conditions for whom HLA matched donors are not available
Presence of zVADfmk and zLLYfmk improves the cell yield and reduces apoptosis during ex vivo expansion We observed a higher incidence of apoptosis, when the cord blood derived CD34+ cells were cultured with cytokines compared to their freshly isolated counterparts (Figure S1)
Cord blood is an established source for stem cell transplantation procedures
Summary
Cord Blood serves as an alternate source of hematopoietic stem cells for patients with malignant and non malignant conditions for whom HLA matched donors are not available. Cord blood possesses several inherent advantages over the bone-marrow– derived hematopoietic stem cells like the ease of procurement and low risk of severe graft-versus-host disease (GVHD) [1]. The expansion culture is known to cause several cellular defects like loss of stem cells, down regulation of adhesion/ migration properties, reduced clonogenicity and initiation of apoptosis [8]. This may render the already fewer stem cells compromised causing an altered marrow engraftment. The present study was undertaken to assess whether pharmacological inhibition of apoptosis could improve the outcome of expansion
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
