Harvests from bone marrow donors who weigh less than their recipients are associated with a significantly increased probability of a suboptimal harvest yield

Supportive Care of Hematopoietic Stem Cell Donors

Supportive care needs for hematopoietic stem cell recipients have been studied. Less is known about the care needs of stem cell donors. Care challenges arise at donor selection, preparation for the donation, the donation procedure and the immediate and long-term after-care. Care needs were analyzed for 1,831 consecutive bone marrow and peripheral stem cell donors at MedStar Georgetown University Hospital between January 2018 and August 2023 in support of a review of the current literature. During the selection, related donors may experience psychological pressures affecting their motivation, while donation centers may be willing to accept co-morbidities in these donors which might preclude donation in unrelated peers. For bone marrow donations, it is important to select donors not only according to optimal genetic matching criteria but also according to suitable donor/recipient weight ratios, to facilitate sufficient stem cell yields. During the donation preparation phase, side effects and complications related to stem cell stimulation must be anticipated and managed for peripheral cell donors, while the pros and cons of autologous blood donation should be evaluated carefully for bone marrow donors. The stem cell donation procedure itself carries potential side effects and complications as well. Peripheral cell donors may require a central line and may encounter hypocalcemia, thrombocytopenia, and anemia. Bone marrow donors face risks associated with anesthesia, blood loss and pain. Post-procedure care focusses on pain management, blood cell recovery and the psychological support necessary to regain a high quality-of-life existence. Hematopoietic stem donors are giving part of themselves to save another's life. They deserve comprehensive supportive care to accompany them throughout the donation process.

Favorable recovery profiles and good reliability among youngest unrelated stem cell donors supports lowering the minimum donor registration age

INTRODUCTION

Younger donor age in hematopoietic cell transplantation has been associated with improved overall and disease-free survival. Safety data on peripheral blood stem cell (PBSC) and bone marrow (BM) donation is well established, including in the <18-year old age group in the related setting. In response, Anthony Nolan became the first stem cell donor registry to lower the minimum age for unrelated donors to 16-years.

MATERIALS AND METHODS

This retrospective study reviewed unrelated donors donating PBSC or BM for the first time between April 2015 and October 2017 since adoption of the lowered recruitment age. Data were collected from registry electronic database and structured follow-up questionnaires. Primary outcomes were turnaround time from VT to donation, optimal cell yield achievement, and physical and emotional recovery.

RESULTS

Out of a total of 1013 donors, there were no differences between the different age groups in proportion of donors achieving optimal CD34+ or TNC (PBSC and BM, respectively). There was no increased central line requirement for younger donors or increased emergency telephone support. Youngest donors were more likely to report physical recovery 2 and 7 days post-PBSC (P = .024 and P = .015, respectively) as well as an earlier emotional recovery (P = .001) and fewer physical symptoms 1 week BM donation (P = .04).

CONCLUSION

This study shows that younger donors are as reliable as older donors, and have favorable recovery profiles without need for increased support at any stage of the donation, supporting Anthony Nolan recruitment strategy and offering reassurance to donor registries considering the same.

Donor characteristics and intraoperative total nucleated cell count influence hematopoietic progenitor cell yield of healthy donor bone marrow grafts

BACKGROUND

Bone marrow graft cell content impacts engraftment potential after allogeneic hematopoietic cell transplantation (alloHCT). Surrogates, such as intraoperative total nucleated cell count (ioTNC), are of unclear utility in predicting final graft characteristics. In addition, demographic and clinical factors may influence graft cellular profile and recipient engraftment.

PROCEDURE

We retrospectively reviewed marrow harvests at our institution performed between 2009 and 2019. During this time, an ioTNC was measured after 50% of the projected final graft volume was collected. Regression models were used to assess associations between ioTNC (cells/µL) and final graft CD34+ (cells/mL), and between graft and donor characteristics and final graft CD34+ (cells/mL).

RESULTS

Fifty-three marrow harvests and donor-recipient pairs were analyzed. Median (range) donor and recipient ages were 13 (0.7-28) years and 9 (0.2-21) years, respectively. The median ratio of donor/recipient weight was 1.225 kg (range 0.31-7.13). Median total volume of harvested marrow was 15.3 mL/kg (range 4.3-20.4) of donor weight and 19.4 mL/kg (range 4.7-87.4) of recipient weight. Median ioTNC was 20 930/µL (range 6600-44310) or 2.1 × 10⁹ /mL, corresponding to median predicted final graft TNC of 3.59 × 10⁸ /kg recipient weight (range 1.28-19.42 × 10⁸ ). Simple linear regression between ioTNC and CD34+ cells/mL resulted in an R² of 0.42. Least absolute shrinkage and selection operator (LASSO) regression produced a moderately predictive model consisting of ioTNC, donor age, and donor weight (adjusted R²  = 0.7) of final graft CD34+ cells/mL.

CONCLUSIONS

ioTNC and certain donor characteristics correlate moderately well with marrow product CD34+ cells/mL, potentially informing donor selection and marrow procurement strategies.

The impact of donor total estimated blood volume on nucleated cell yield in bone marrow harvests for hematopoietic stem cell transplantation

BACKGROUND

Nucleated cell yields of marrow harvests depend on factors related to donors, the procedure itself, and the volume of marrow harvested. Few attempts have been made to relate donor characteristics to harvest volume. We hypothesize that the percentage of total donor blood volume accessed for harvesting impacts the nucleated cell yield per ml of marrow collected.

METHODS AND MATERIALS

We investigated 481 consecutive unrelated marrow harvests from a single center. Donor characteristics including weight, body mass index (BMI), white blood cells (WBCs), hemoglobin (Hgb), and platelet counts, as well as estimated total blood volume, were recorded and compared with nucleated cell yields and harvest volumes.

RESULTS

The percentage of donor blood volume accessed for marrow harvesting was inversely related to nucleated cell yields (r = -0.57). The donor-recipient weight differential impacted cell yields as well (r = 0.35), with heavier recipients requiring increased marrow volumes from smaller donors to satisfy their nucleated cell needs. 3.73 × 10⁸ /kg of recipient weight could be collected with 95% certainty when harvest volumes did not exceed 16.1% of donor total blood volume. In a stepwise multiple regression analysis, 45.4% of cell yield variance was explained by blood volume percentage accessed for harvesting, donor weight, and WBC. Donor sex, BMI, and platelet counts did not contribute further to cell yield variance. Smokers had higher cell yields than nonsmokers (20.4 vs. 18.3 × 10⁶ /ml; 95% confidence interval 0.62, 3.47) independent of other parameters.

CONCLUSION

Establishing the relationship between percentage of estimated donor total blood volume and recipient cell needs can facilitate donor selection for successful hematopoietic cell (HPC) transplants.

Pre- and post-bone marrow harvest anaemia is associated with lower CD34+ stem cell collection, high harvest volume and female gender

BACKGROUND

Donor safety is paramount when performing bone marrow stem cell harvest. The incidence of full blood count (FBC) abnormalities among donors and variables associated with anaemia after marrow harvest are not well established.

AIMS

To describe the frequency of FBC abnormalities prior to bone marrow stem cell harvest and to identify variables associated with post harvest anaemia.

METHODS

Outcomes of 80 consecutive adult marrow harvests performed at our centre were analysed retrospectively.

RESULTS

FBC abnormalities were present in 28% of donors prior to marrow harvest with normocytic anaemia the most common abnormality in 13%. Reduced donor haemoglobin (Hb) was independently correlated with lower CD34+ cell count per kg of recipient body weight. Anaemia (Hb < 100 g/L) was seen in 20% of donors after harvest with median decrease in Hb of 19 g/L. Variables independently associated with anaemia after harvest included donor to recipient weight ratio (P = 0.011), high collection volume (P = 0.044) and female gender (P = 0.023). Total nucleated cell and CD34 concentration in the final collected product were associated with the inverse of harvested marrow volume (P < 0.001).

CONCLUSIONS

Pre-harvest anaemia should be corrected where possible particularly in female donors. Marrow collection volume should be minimised to reduce post-harvest anaemia, optimise CD34+ cell number and improve nucleated and stem cell concentrations in the harvest product.

The Concentration of Total Nucleated Cells in Harvested Bone Marrow for Transplantation Has Decreased over Time

Bone marrow (BM) is an essential source of hematopoietic stem cell grafts for many allogeneic hematopoietic cell transplant (HCT) recipients, including adult patients (for specific diseases and transplantation strategies) and the majority of pediatric recipient. However, since the advent of granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts, there has been a significant decrease in the use of BM in HCT, thought to be due mainly to the increased logistical challenges in harvesting BM compared with PBSCs, as well as generally no significant survival advantage of BM over PBSCs. The decreased frequency of collection has the potential to impact the quality of BM harvests. In this study, we examined >15,000 BM donations collected at National Marrow Donor Program centers between 1994 and 2016 and found a significant decline in the quality of BM products, as defined by the concentration of total nucleated cells (TNCs). The mean TNC concentration in BM donations dropped from 21.8 × 10⁶ cells/mL in the earliest era (1994 to 1996) to 18.7 × 10⁶ cells/mL in the most recent era (2012 to 2016) (means ratio, .83; P < .001). This decline in BM quality was seen despite the selection of more donors perceived to be optimal (eg, younger and male). Multivariate regression analysis showed that higher-volume centers (performing >30 collections per era) had better-quality harvests with higher concentrations of TNCs collected. In conclusion, we have identified a significant decrease in the quality of BM collections over time, and lower-volume collection centers had poorer-quality harvests. In this analysis, we could not elucidate the direct cause for this finding, suggesting the need for further studies to investigate the key factors responsible and to explore the impact on transplant recipients.

Peripheral Blood or Bone Marrow Stem Cells? Practical Considerations in Hematopoietic Stem Cell Transplantation

Although peripheral blood stem cells (PBSC) have worldwide become the predominant source of progenitor cells for hematopoietic stem cell transplantation (HSCT), debate about their role compared with bone marrow (BM) has recently intensified, in large part based on the results of a multicenter Clinical Trials Network study which showed lower incidence of chronic graft-versus-host disease (cGVHD) and improved quality of life in recipients of myeloablative HLA-matched unrelated BM compared with PBSC transplants. However, in certain patient populations, PBSC may lead to improved clinical outcomes due to faster hematologic recovery, a lower risk of graft failure, and possibly a lower probability of relapse. This review will provide a comprehensive summary of studies comparing PBSC with BM as the graft source in terms of acute and chronic GVHD incidence, time to engraftment, and disease-free and overall survival probabilities after HLA-matched related and unrelated donor transplantation and haploidentical donor transplantation. Recommendations based on these studies regarding the use of PBSC versus BM for HSCT are offered.

Bone marrow harvest in donors with anaemia

BACKGROUND

Bone marrow harvest (BMH) for haematopoietic stem cell transplantation is a well-established procedure. The guidelines of World Marrow Donor Association provide information on donor selection. However, some of the guidelines regarding donors with anaemia prior to harvest lack in supporting data from clinical studies. With this study, we aimed to provide such data.

MATERIAL AND METHODS

In this retrospective, single-centre study, we analysed the interplay between haemoglobin levels and BMH and BMH impact on haemoglobin levels in a cohort of 149 unrelated BM donors, including 13 subjects with mild anaemia.

RESULTS

The BMH led to significantly lower decrease in haemoglobin levels in donors with anaemia than in control group (1·79 g/dl vs. 2·56 g/dl, P < 0·0001). The following parameters: BMH volume (ml), BMH volume/donor body weight (ml/kg), total nucleated cells (TNC) in product (×10⁸ ) and TNC/kg recipient body weight in product (×10⁸ /kg) did not differ significantly between those two analysed groups (P > 0·05). Median BM volume harvested from anaemic donors was 16·34 ml/kg; none of them required blood transfusion after BMH.

CONCLUSION

Mild anaemia prior to BMH does not significantly impact the collection results. The BMH is safe and feasible in donors with mild anaemia.

Bone marrow harvest from unrelated donors-up-to-date methodology

OBJECTIVES

Bone marrow harvesting is one of the essential sources of stem cells for hematopoietic stem cell transplantation. We describe here the current "up-to-date" standard of the bone marrow harvest in unrelated stem cell donors.

METHODS

We analyzed medical data of 187 unrelated hematopoietic stem cell donors who underwent bone marrow harvest without previous peripheral blood stem collection at the center between 2011 and 2015. The methodology of marrow collection includes multiple cells aimed at safety of the procedure, for example, educational movie, modified skin disinfection protocol, cell enumeration during the procedure, reduction of the contamination surfaces, and ongoing monitoring of the quality of work of the doctors.

RESULTS

The total nucleated cell count over 2×10⁸ per kg of recipient has been reached in 93.6% of harvests. All of the donors harvested more than 1×10⁸ per kg of the recipient. There were no donors who required transfusions or had serious adverse events during and after the harvest.

CONCLUSION

We describe here the current up-to-date standard of bone marrow harvest, which leads to excellent results in majority of donors without causing significant complications during the donation.

Development of an Unrelated Donor Selection Score Predictive of Survival after HCT: Donor Age Matters Most

Donor factors, in addition to HLA matching status, have been associated with recipient survival in unrelated donor (URD) hematopoietic cell transplantation (HCT); however, there is no hierarchical algorithm that weights the characteristics of individual donors against each other in a quantitative manner to facilitate donor selection. The goal of this study was to develop and validate a donor selection score that prioritizes donor characteristics associated with better survival in 8/8 HLA-matched URDs. Two separate patient/donor cohorts, the first receiving HCT between 1999 and 2011 (n = 5952, c1), and the second between 2012 and 2014 (n = 4510, c2) were included in the analysis. Both cohorts were randomly spilt, 2:1, into training and testing sets. Despite studying over 10,000 URD transplants, we were unable to validate a donor selection score. The only donor characteristic associated with better survival was younger age, with 2-year survival being 3% better when a donor 10 years younger is selected. These results support previous studies suggesting prioritization of a younger 8/8 HLA-matched donor. This large dataset also shows that none of the other donor clinical factors tested were reproducibly associated with survival, and hence flexibility in selecting URDs based on other characteristics is justified. These data support a simplified URD selection process and have significant implications for URD registries.