Outcomes of transplantation of unrelated donor umbilical cord blood and bone marrow in children with acute leukaemia: a comparison study. Editorial comment

Outcomes of transplantation of unrelated donor umbilical cord blood and bone marrow in children with acute leukaemia: a comparison study

Rationale: The regenerative potential of the heart is insufficient to fully restore functioning myocardium after injury, motivating the quest for a cell-based replacement strategy. Bone marrow–derived mesenchymal stem cells (MSCs) have the capacity for cardiac repair that appears to exceed their capacity for differentiation into cardiac myocytes.

Objective: Here, we test the hypothesis that bone marrow derived MSCs stimulate the proliferation and differentiation of endogenous cardiac stem cells (CSCs) as part of their regenerative repertoire.

Methods And Results: Female Yorkshire pigs (n=31) underwent experimental myocardial infarction (MI), and 3 days later, received transendocardial injections of allogeneic male bone marrow–derived MSCs, MSC concentrated conditioned medium (CCM), or placebo (Plasmalyte). A no-injection control group was also studied. MSCs engrafted and differentiated into cardiomyocytes and vascular structures. In addition, endogenous c-kit+ CSCs increased 20-fold in MSC-treated animals versus controls ( P <0.001), there was a 6-fold increase in GATA-4+ CSCs in MSC versus control ( P <0.001), and mitotic myocytes increased 4-fold ( P =0.005). Porcine endomyocardial biopsies were harvested and plated as organotypic cultures in the presence or absence of MSC feeder layers. In vitro, MSCs stimulated c-kit+ CSCs proliferation into enriched populations of adult cardioblasts that expressed Nkx2–5 and troponin I.

Conclusions: MSCs stimulate host CSCs, a new mechanism of action underlying successful cell-based therapeutics.

# Novelty and Significance {#article-title-52}

Bone Marrow Mesenchymal Stem Cells Stimulate Cardiac Stem Cell Proliferation and Differentiation

Summary Background Umbilical-cord blood (UCB) is increasingly considered as an alternative to peripheral blood progenitor cells (PBPCs) or bone marrow, especially when an HLA-matched adult unrelated donor is not available. We aimed to determine the optimal role of UCB grafts in transplantation for adults with acute leukaemia, and to establish whether current graft-selection practices are appropriate. Methods We used Cox regression to retrospectively compare leukaemia-free survival and other outcomes for UCB, PBPC, and bone marrow transplantation in patients aged 16 years or over who underwent a transplant for acute leukaemia. Data were available on 1525 patients transplanted between 2002 and 2006. 165 received UCB, 888 received PBPCs, and 472 received bone marrow. UCB units were matched at HLA-A and HLA-B at antigen level, and HLA-DRB1 at allele level (n=10), or mismatched at one (n=40) or two (n=115) antigens. PBPCs and bone-marrow grafts from unrelated adult donors were matched for allele-level HLA-A, HLA-B, HLA-C, and HLA-DRB1 (n=632 and n=332, respectively), or mismatched at one locus (n=256 and n=140, respectively). Findings Leukaemia-free survival in patients after UCB transplantation was comparable with that after 8/8 and 7/8 allele-matched PBPC or bone-marrow transplantation. However, transplant-related mortality was higher after UCB transplantation than after 8/8 allele-matched PBPC recipients (HR 1·62, 95% CI 1·18–2·23; p=0·003) or bone-marrow transplantation (HR 1·69, 95% CI 1·19–2·39; p=0·003). Grades 2–4 acute and chronic graft-versus-host disease (GvHD) were lower in UCB recipients compared with allele-matched PBPC (HR 0·57, 95% 0·42–0·77; p=0·002 and HR 0·38, 0·27–0·53; p=0·003, respectively), while the incidence of chronic, but not acute GvHD, was lower after UCB than after 8/8 allele-matched bone-marrow transplantation (HR 0·63, 0·44–0·90; p=0·01). Interpretation These data support the use of UCB for adults with acute leukaemia when there is no HLA-matched unrelated adult donor available, and when a transplant is needed urgently. Funding National Cancer Institute, National Heart Lung and Blood Institute, National Institute of Allergy and Infectious Disease (U24-CA76518); Health Resources and Services Administration (HHSH234200637015C); Office of Naval Research, Department of Navy (N00014-08-1-1207); Children's Leukemia Research Association; and a Scholar in Clinical Research Award from the Leukemia and Lymphoma Society.

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Effect of graft source on unrelated donor haemopoietic stem-cell transplantation in adults with acute leukaemia: a retrospective analysis

Allogeneic hematopoietic cell transplantation for hematologic malignancy: relative risks and benefits of double umbilical cord blood

One factor limiting the therapeutic efficacy of cord blood (CB) hematopoietic progenitor cell (HPC) transplantation is the low cell dose of the graft. This is associated with an increased incidence of delayed or failed engraftment. Cell dose can be increased and the efficacy of CB transplantation potentially improved, by ex vivo CB expansion before transplantation. Two ex vivo CB expansion techniques were compared: (1) CD133+ selection followed by ex vivo liquid culture and (2) co-culture of unmanipulated CB with bone-marrow-derived mesenchymal stem cells (MSCs). Ex vivo culture was performed in medium supplemented with granulocyte colony-stimulating factor, stem cell factor and either thrombopoietin or megakaryocyte growth and differentiation factor. Expansion was followed by measuring total nucleated cell (TNC), CD133+ and CD34+ cell, colony-forming unit and cobblestone area-forming cell output. When compared to liquid culture, CB-MSC co-culture (i) required less cell manipulation resulting in less initial HPC loss and (ii) markedly improved TNC and HPC output. CB-MSC co-culture therefore holds promise for improving engraftment kinetics in CB transplant recipients.

Superior ex vivo cord blood expansion following co-culture with bone marrow-derived mesenchymal stem cells.

Ex vivo expansion of umbilical cord blood

Superior EX vivo cord blood TNC and hematopoietic progenitor cell expansion following co-culture with bone marrow-derived mesenchymal stem cells

Cord blood (CB) is a valuable graft source for patients undergoing allogeneic hematopoietic cell transplant (HCT) who lack human leukocyte antigen (HLA)-matched donors. However, single-unit CB-HCT is limited by the insufficient cell dose and slow engraftment. To overcome these limitations, we combined a single-unit CB with third-party healthy donors’ bone marrow (BM) derived mesenchymal stromal cells (MSCs) to improve engraftment and injected intra-osseously (IO) to enhance homing. In this phase I clinical trial, six patients with high-risk hematologic malignancies were enrolled and received allogeneic HCT using reduced intensity conditioning regimens. The primary objective was to determine the engraftment rate at day 42. The median age of enrolled patients was 68 years, and only one patient was in complete remission at the time of HCT. The median CB total nucleated cell dose was 3.2x107/kg. No serious adverse events were reported. Two patients had early deaths due to persistent disease and multi-drug resistant bacterial infection, respectively. Of the remaining four evaluable patients, all had successful neutrophil engraftment in a median of 17.5 days. No grade 3 or higher acute graft-versus-host disease (GvHD) was observed, and only one patient developed moderate-extensive chronic GvHD. In conclusion, IO co-transplantation of a single-unit CB and MSCs was feasible and resulted in a reasonable engraftment rate in these very high-risk patients.

https://www.frontiersin.org/articles/10.3389/fonc.2023.1186532/pdf

Phase I study of intra-osseous co-transplantation of a single-unit cord blood and mesenchymal stromal cells with reduced intensity conditioning regimens

P. Fu

Papers

Superior ex vivo cord blood expansion following co-culture with bone marrow-derived mesenchymal stem cells.

Ex vivo expansion of umbilical cord blood

Superior EX vivo cord blood TNC and hematopoietic progenitor cell expansion following co-culture with bone marrow-derived mesenchymal stem cells

Phase I study of intra-osseous co-transplantation of a single-unit cord blood and mesenchymal stromal cells with reduced intensity conditioning regimens