Establishment of reference values based on influential characteristics of hematopoietic stem cells and immune cell subsets in the bone marrow

Hematopoietic stem cell transplantation is still a curative treatment for many haematological cancers. Many factors, such as age, sex, ethnic background, smoking status, and body mass index, affect average reference values in different populations. This study aimed to establish a reference range for the absolute numbers and percentages of healthy individuals' hematopoietic stem cells and immune cells in the bone marrow. Seventy-one healthy donors (32 males and 39 females) were enrolled in the study. Following bone marrow harvesting, using flow cytometry, immunophenotyping was performed to determine the absolute number and percentage of CD34+ stem cells and various immune subsets. We found no statistically significant difference in the absolute count of HSCs or immune cell subsets in the bone marrow between males and females. Regarding age, the younger group had more significant CD34+ and immune cell subsets. Donors with healthier body weights tend to have richer bone marrow cellularity. Establishing a reference value for hematopoietic stem cells and immune cells in the bone marrow based on various influential factors is pivotal for defining bone marrow status and donor selection.

A case of acute lung injury in a peripheral blood stem cell donor mobilized with pegylated recombinant human granulocyte colony-stimulating factor

Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) has been introduced for the mobilization of peripheral blood stem cells (PBSCs). However, no cases of acute lung injury (ALI) in healthy donors have been reported, and the underlying mechanisms remain poorly understood. We first reported a case of ALI caused by PEG-rhG-CSF in a healthy Chinese donor, characterized by hemoptysis, hypoxemia, and patchy shadows. Ultimately, hormone administration, planned PBSC collection, leukocyte debridement, and planned PBSC collection resulted in active control of the donor's ALI. The donor's symptoms improved without any adverse effects, and the PBSC collection proceeded without incident. Over time, the lung lesion was gradually absorbed and eventually returned to normal. PEG-rhG-CSF may contribute to ALI in healthy donors via mechanisms involving neutrophil aggregation, adhesion, and the release of inflammatory mediators in the lung. This case report examines the clinical manifestations, treatment, and mechanism of lung injury induced by PEG-rhG-CSF-mobilized PBSCs.

Peripheral Blood Allogeneic Stem Cell Mobilization: Can We Predict a Suboptimal Mobilization?

Allogeneic peripheral blood stem cells mobilization is now the basis of most stem cell transplants. In a very limited number of cases, mobilization is suboptimal leading to further collection procedures, to suboptimal cell doses infusion with delayed engraftment time, increased risks of transplant procedure and of related costs. To date we have no recognized and shared criteria for early estimating the probability of poor mobilization in healthy donors. We then analyzed allogeneic peripheral blood stem cell donations performed at the Fondazione Policlinico Universitario A.Gemelli IRCCS Hospital from January 2013 to December 2021 in order to identify premobilization factors associated with successful mobilization. The following data were collected: age, gender, weight, complete blood cell count at baseline, G-CSF dose, number of collection procedures, CD34+ cell count in peripheral blood on the first day of collection, CD34+ cell dose per kg body weight of recipient. Mobilization efficacy was defined according to the number of CD34+ cells in peripheral blood on day +5 of G-CSF administration. We classified donors as sub-optimal mobilizers or good mobilizers according to the achievement of the 50 CD34+ cell/μL threshold. We observed 30 suboptimal mobilizations in 158 allogeneic peripheral blood stem cell donations. Age and baseline white blood cell count were factors significantly associated with negative or positive impact on mobilization, respectively. We did not find significant differences in mobilization based on gender or G-CSF dose. Using cut-off values of 43 years and 5.5×10⁹/L WBC count, we built a suboptimal mobilization score: donors who reach 2, 1 or 0 points have a 46%, 16% or 4% probability of suboptimal mobilization, respectively. Our model explains 26% of the variability of mobilization confirming that most of the mobilization magnitude depends on genetically determined factors; however, suboptimal mobilization score is a simple tool providing an early assessment of mobilization efficacy before G-CSF administration begins in order to support allogeneic stem cells selection, mobilization and collection. Through a systematic review, we looked for confirmation of our findings. According to the published articles, all the variables we included in our model are confirmed to be strongly related to the success of mobilization. We believe that score system approach could be applied in clinical practice to assess the risk of mobilization failure at baseline allowing for a priori intervention.

Addition of plerixafor to G-CSF in poor mobilizing healthy related donors overcame mobilization failure: An observational case series on behalf of the Grupo Español de Trasplante Hematopoyético (GETH)

Plerixafor (Mozobil, Sanofi) is approved for using in patients with lymphoma and multiple myeloma when steady-state mobilization strategies fail. Although off-label use of plerixafor in healthy related donors (HRD) is known, limited data are available and no recommendations exist to guide its use in this setting. With the aim of collecting data from HRDs who received plerixafor in our country, we designed an observational case series study within the Spanish Group of Hematopoietic Transplant and Cell Therapy (GETH). Plerixafor was administered subcutaneously to 30 HRDs at a median dose of 0.24 mg/Kg (interquartile range (IQR): 0.23-0.25) because mobilization failure after using mobilization with G-CSF (mobilization failure was defined as collection of <4.0 × 10⁶ CD34+ cells/Kg recipient). All HRDs received G-CSF at a median dose of 11 μg/Kg/day (IQR: 10-12) for 4-5 days. Leukocytapheresis after G-CSF mobilization was performed in 23 (77 %) HRDs collecting a median of 1.6 × 10⁶ CD34+ cells/Kg recipient weight (IQR: 0.9-2.5). Addition of plerixafor allowed the collection of a higher median number of CD34 cells (4.98 × 10⁶ CD34+ cells/Kg recipient weight (IQR: 3.5-5.8)) when compared with the collection of CD34+ cells with G-CSF alone (p < 0.01). The final median total number of CD34+ cells collected was 6.1 × 10⁶/Kg recipient weight (IQR: 4.8-7.3). Mild adverse events related with plerixafor administration were reported in 8 (27 %) donors. In conclusion, addition of plerixafor after G-CSF mobilization failure in HRDs allowed collecting higher number of CD34+ cells in comparison with steady-state mobilization.

Severe Hypoxemia in a Healthy Donor for Allogeneic Hematopoietic Stem Cell Transplantation after Only the First Administration of Granulocyte-Colony Stimulating Factor

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) is widely used to mobilize peripheral blood stem cells (PBSCs) in healthy donors. A few reports have shown that some healthy donors developed acute respiratory distress syndrome or capillary leak syndrome after more than several rounds of G-CSF administration or leukapheresis.

CASE REPORT

We report the case of a healthy donor for allogeneic stem cell transplantation who developed severe hypoxemia 1 h after only the first administration of G-CSF. The donor was administered 10 μg/kg G-CSF (lenograstim) subcutaneously for PBSC mobilization. 1 h after the first administration of G-CSF, the donor suddenly presented with dry cough and dyspnea. The oxygen saturation by pulse oximetry (SpO₂) in the room air was 88%. An electrocardiogram and chest radiography revealed no abnormalities. We excluded other causes of severe hypoxemia and diagnosed the donor with hypoxemia due to G-CSF administration, which was subsequently terminated. The donor was administered 2 l/min oxygen via a nasal cannula and 100 mg hydrocortisone intravenously. He subsequently recovered, and SpO₂ in the room air returned to 98% 10 h after hypoxemia.

CONCLUSION

These respiratory symptoms might be related to anaphylactoid or hypersensitivity reaction. The donors should be observed for at least 1 h after the first administration of G-CSF.

The Milieu Intérieur study - an integrative approach for study of human immunological variance

The Milieu Intérieur Consortium has established a 1000-person healthy population-based study (stratified according to sex and age), creating an unparalleled opportunity for assessing the determinants of human immunologic variance. Herein, we define the criteria utilized for participant enrollment, and highlight the key data that were collected for correlative studies. In this report, we analyzed biological correlates of sex, age, smoking-habits, metabolic score and CMV infection. We characterized and identified unique risk factors among healthy donors, as compared to studies that have focused on the general population or disease cohorts. Finally, we highlight sex-bias in the thresholds used for metabolic score determination and recommend a deeper examination of current guidelines. In sum, our clinical design, standardized sample collection strategies, and epidemiological data analyses have established the foundation for defining variability within human immune responses.