Bone marrow as a source of hematopoietic stem cells for human gene therapy of β-thalassemia

β-Thalassemia is a severe inherited anemia caused by insufficient production of β-globin chains. Allogeneic hematopoietic stem cell (HSC) transplantation is currently the only cure, and is limited by donor availability and regimen-related toxicity and mortality. Gene therapy is a promising therapeutic tool for all thalassemic patients lacking a compatible donor and potentially provides transfusion independence in the absence of transplant-related complications, such as graft rejection and graft-versus-host disease. The issue of HSC procurement is critical in this setting because of the specific features of thalassemic syndromes, which include bone marrow (BM) expansion, ineffective erythropoiesis, and splenomegaly. Little is known about the efficiency of CD34(+) cell yield from steady-state BM harvests from thalassemic patients. We have collected data on safety and cell yield from 20 pediatric patients with β-thalassemia who underwent autologous BM harvest before allogeneic HSC transplantation, and from 49 age-matched sibling donors who also underwent BM harvest. The procedure was safe, as no significant adverse events occurred. In terms of cell yield, no difference was found between patients and normal donors in the number of CD34(+) cells and total nucleated cells harvested. Most importantly, no difference was found in the proportion of myeloid and erythroid progenitors, suggesting a similar repopulating capacity. On the basis of these results, we conclude that steady-state BM can be used as a safe and efficient source of HSC for gene therapy of β-thalassemia.     

New agents for mobilizing peripheral blood stem cells

Transplantation with bone marrow (BM) hematopoietic stem cells (HSC) has been used for curative therapy of hematologic diseases and inborn errors of metabolism for decades. More recently, alternative sources of HSC, particularly those induced to exit marrow and traffic to peripheral blood in response to external stimuli, have become the most widely used hematopoietic graft and show significant superiority to marrow HSC. Although a variety of agents can mobilize stem cells with different kinetics and efficiencies and these agents can be additive or synergistic when used in combination, currently G-CSF is the predominant stem cell mobilizer used clinically based upon potency, predictability and safety. Recent studies have demonstrated that the interaction between the chemokine stromal-derived factor 1 (SDF-1/CXCL12) and its receptor CXCR4 serves as a key regulator of HSC trafficking. AMD3100, a novel bicyclam CXCR4 antagonist, induces the rapid mobilization of HSC with both short- and long-term repopulation capacity. Mobilization with G-CSF and AMD3100 in clinical trials resulted in more patients achieving sufficient PBSC for transplantation than with G-CSF alone. Thus, chemokine axis-mobilization could allow rapid PBSC harvests with increased cell yields in difficult-to mobilize patients. Studies of autologous and allogeneic transplantation of AMD3100 mobilized grafts demonstrated prompt and stable engraftment.Enhanced homing properties of chemokine axis-mobilized PBSC suggest that these cells may have greater therapeutic utility in other areas including tissue repair and regeneration.     

Application of peripheral blood stem cells (PBSC) mobilized by recombinant human granulocyte colony stimulating factor for allogeneic PBSC transplantation and the comparison of allogeneic PBSC transplantation and bone marrow transplantation.

Recombinant human granulocyte colony stimulating factor (rhG-CSF)-mobilized peripheral blood stem cells (PBSC) are now widely used for allogeneic PBSC transplantation (alloPBSCT). Large numbers of hematopoietic progenitor cells mobilized by rhG-CSF would be considered equivalent or better than bone marrow (BM) cells and would be used as an alternative to BM for allogeneic hematopoietic stem cell transplantation. The complications associated with the administration of rhG-CSF and apheresis in PBSC collection in formal donors are well tolerated and usually acceptable in the short term but some hazardous adverse events such as splenic rupture and cardiac arrest are reported although the incidence is very low. Protective means and stopping rules for safe donation in the collection of PBSC are established. The characteristics of PBSC were clarified; the expression of some adhesion molecules such as CD49d on CD34 positive cells of PBSC have been shown to be low compared to BM stem cells. In alloPBSCT compared with allogeneic BM transplantation (alloBMT), the incidence and frequency of graft versus host disease (GVHD) is of concern because high number of T lymphocytes are infused in alloPBSCT. The incidence and severity of acute GVHD are not increased but chronic GVHD is higher in alloPBSCT compared with alloBMT. The outcome of alloPBSCT and BMT are almost equivalent and conclusive results regarding survival are not yet available.     

异基因造血干细胞移植治疗儿童再生障碍性贫血临床分析

目的探讨异基因造血于细胞移植治疗儿童再生障碍性贫血（简称再障）的疗效。方法6例再障患儿中,5例行G．CSF动员的HLA全相合同胞供体骨髓联合外周血造血干细胞移植,平均输入骨髓单个核细胞数4．61（1．5～13．2）×10^8／kg,平均输入外周血单个核细胞数9．36（2．05～16．75）×10^8／kg。预处理方案采用FLU＋CTX＋ATG。1例实行无关供体HLA全相合骨髓移植,输入骨髓单个核细胞数16．8×10^8／kg。预处理方案采用FLU＋CTX＋TBI。急性GVHD预防均采用CSA＋MTX。结果1例移植失败,未植入,移植后第23天自体造血功能恢复。余5例均植入。所有患者均无GVHD的发生。1例病史4年的轻型再障患儿在移植后1年4个月时移植排斥,再障复发合并重症感染治疗无效死亡;余5例随访至2009年2月均无病存活。结论HLA全相合的同胞间骨髓联合外周血造血干细胞移植可作为治疗儿童再障的首选治疗方法;免疫抑制治疗失败且无合适同胞供者的再障患儿可以选择无关供体HLA全相合骨髓移植。     

Seasonal variation of human physiology does not influence the harvest of peripheral blood CD34+ cells from unrelated hematopoietic stem cell donors

There are many reports on factors predicting the outcome of PBSC (peripheral blood stem cell) mobilization, such as the donor’s gender, age, weight, white blood cell count, platelets pre apheresis, LDH and iron status. Although there are reports of seasonal variation in the physiology of the human immune system and hematopoiesis there are no data that such differences play a role in the response to G-CSF in healthy hematopoietic stem cell donors. The response to G-CSF could also impact the collection results during different seasons. To assess the possible impact of seasonal variation we performed a retrospective, single-center analysis of mobilization and harvest of PBSC in 330 healthy unrelated donors. We found no significant differences in the number of CD34+ cells in peripheral blood after G-CSF mobilization and in collection results when all donors were analyzed. In the subgroup of male donors the number of CD34+ stem cells after G-CSF mobilization was higher than average in summer and autumn (p = 0.036), however, it did not translate into clinically relevant differences in stem cell harvest.We conclude that although there is possible seasonal variation in the response to G-CSF in male donors there is no impact on PBSC harvest in healthy unrelated donors.     

Mobilization and collection of peripheral blood progenitor cells for transplantation.

Bone marrow transplantation gradually expanded as a treatment modality for various malignant and non malignant disease conditions. Since the discoveries of the potential of Peripheral Blood Progenitor Cells (PBPC) in the hematopoietic reconstitution mid 1980s and early 1990s PBPC gradually replaced bone marrow as the preferred source of stem cells. The introduction of hematopoietic cytokines that can mobilize large number of progenitors into circulation accelerated PBPC usage. Technological advancements in the apheresis instrumentation greatly helped in the conversion from marrow to PBPC. PBPC collection is less painful, less expensive and transplant with PBPC results in faster hematological recovery than with marrow. Almost all of the autologous transplants are currently performed with PBPC and a similar trend is seen with the allogeneic transplants. The progenitor cell mobilization regimen for autologous patients can be cytokines alone or cytokines combined with chemotherapy. In the majority of the patients the required minimal cell dose of 2.5-5.0 x 10(6)/kg CD34+ cells can be collected in one or two apheresis collections. A few of autologous transplant patients who mobilize poorly require several collections. Allogeneic donors are generally mobilized with daily subcutaneous injections of G-CSF 10 microg/kg for 5 days. The PBPC are collected in one or two apheresis procedures. The side effects of G-CSF are generally mild to moderate; however rare serious reactions including rupture of the spleen have been reported. The collection of PBPC in pediatric patients poses additional challenges yet an adequate dose of cells can be collected with the available apheresis instrumentation. The apheresis collection procedures are safe with no serious adverse consequences. Future scientific advancements may expand the use of PBPC for other clinical application in addition to the current use for hematological reconstitution.     

G-CSF联合普乐沙福动员异基因造血干细胞移植亲缘健康供者外周血造血干细胞的单中心分析

目的:研究粒细胞集落刺激因子(G-CSF)联合普乐沙福对异基因造血干细胞移植(allo-HSCT)的亲缘健康供者外周血造血干细胞动员的效果及安全性。方法:回顾性分析2019年4月至2021年4月在河北燕达陆道培医院采用G-CSF联合普乐沙福动员方案的亲缘健康供者33例(观察组),应用G-CSF细胞动员d 4采集骨髓,d 5采集外周血造血干细胞(PBSC),d 5晚加用普乐沙福,并于d 6再次采集PBSC。随机选取历史同期采用单独G-CSF方案动员的亲缘健康供者46例作为对照组,分析2组供者d 5和d 6 PBSC采集物中CD34⁺细胞计数。以调查问卷的方式观察供者普乐沙福给药后的不良反应。分析接受"G-CSF+普乐沙福"动员方案的allo-HSCT患者和仅接受"G-CSF"动员方案的造血干细胞移植患者在移植后100天总a GVHD、Ⅲ-Ⅳ度a GVHD、CMV血症和EBV血症的发生方面的差异。结果:观察组在d 5和d 6 PBSC采集物中CD34⁺细胞数(M±Q)分别为(1.71±1.02)×10⁶/kg和(4.23±2...     

亲缘与非亲缘供者造血干细胞动员和采集的安全性比较

本研究对捐献骨髓及外周造血干细胞的健康亲缘供者及只捐献外周造血干细胞的非亲缘供者,在造血干细胞动员和采集的安全性方面进行比较。对2005年9月至2006年8月在北京大学人民医院血液病研究所提供异基因造血干细胞的亲缘供者100例及2003年11月至2007年12月在中国造血干细胞捐献者资料库北京管理中心登记的非血缘供者71例,在造血干细胞动员、采集及采集后1、3、6个月及每年进行了评估。对血常规指标、不良反应等进行观察记录,并对随访期间的长期不良反应及生活质量进行了问卷调查。结果显示：亲缘供者提供的骨髓＋外周血干细胞总MNC剂量为6．70（4．11—12．23）×10^8／kg,总CD34^＋细胞剂量为3．40（1．61—13．57）×10^6／kg：非亲缘供者提供的外周血干细胞总MNC剂量为6．69（3．35-11．48）×10^8／kg,总CD34^＋细胞剂量为3．50（1．15—11．60）×10^6／kg。动员时的常见副作用为骨痛,在亲缘供者的发生率为47％,在非亲缘供者的发生率为43．7％,两组之间无显著性差异;采集时的常见副作用为感觉异常（口唇和四肢）,在亲缘供者的发生率为25％,在非亲缘供者的发生率为29．6％,两组之间无显著性差异;所有供者对副作用皆可耐受,没有供者因为不能耐受而中断采集。亲缘供者由于骨髓和外周血的采集,其血红蛋白水平低于非亲缘供者[（125．8±20．2）g／L vs（143．2±20．1）g／L]（P〈0．05）。非亲缘供者由于外周干细胞采集多为2次,其血小板计数低于亲缘供者[（126．2±57．2）×10^9／L vs（162．4±72．9）×10^9／L]（P〈0．05）。在长期随访中,亲缘供者与非亲缘供者的血常规检查结果比较无显著性差异,无长期的不良反应,健康状况良好。结论：亲缘与非亲缘供者进行造血干细胞采集都是安全可行的。术前进行完备的检查,术中仔细操作、严密观察,及术后长期随访对于供者的安全有重要的意义。     

Stem cell collection in unmanipulated HLA‐haploidentical/mismatched related transplantation with combined granulocyte‐colony stimulating factor‐mobilised blood and bone marrow for patients with haematologic malignancies: the impact of donor characteristics and procedural settings

Unmanipulated haploidentical/mismatched related transplantation with combined granulocyte‐colony stimulating factor‐mobilised peripheral blood stem cells (G‐PBSCs) and granulocyte‐colony stimulating factor‐mobilised bone marrow (G‐BM) has been developed as an alternative transplantation strategy for patients with haematologic malignancies. However, little information is available about the factors predicting the outcome of peripheral blood stem cell (PBSC) collection and bone marrow (BM) harvest in this transplantation. The effects of donor characteristics and procedure factors on CD34⁺ cell yield were investigated. A total of 104 related healthy donors received granulocyte‐colony stimulating factor (G‐CSF) followed by PBSC collection and BM harvest. Male donors had significantly higher yields compared with female donors. In multiple regression analysis for peripheral blood collection, age and flow rate were negatively correlated with cell yield, whereas body mass index, pre‐aphaeresis white blood cell (WBC) and circulating immature cell (CIC) counts were positively correlated with cell yields. For BM harvest, age was negatively correlated with cell yields, whereas pre‐BM collection CIC counts were positively correlated with cell yield. All donors achieved the final product of ≥6 ×10⁶ kg^?1 recipient body weight. This transplantation strategy has been shown to be a feasible approach with acceptable outcomes in stem cell collection for patients who received HLA‐haploidentical/mismatched transplantation with combined G‐PBSCs and G‐BM. In donors with multiple high‐risk characteristics for poor aphaeresis CD34⁺ cell yield, BM was an alternative source.     

Haploidentical stem cell transplantation-bone marrow vs peripheral blood

Hematopoietic stem cells may be obtained by collection of bone marrow, mobilization and collection of peripheral blood stem cells or umbilical cord blood. Transplantation of peripheral blood hematopoietic cells has increased due to faster engraftment and practicability in both the related, unrelated or haploidentical setting. We reviewed the question of which stem cell source - bone marrow (BM) or peripheral blood (PBSC) - is the most suitable for individuals undergoing haploidentical stem cell transplantation. BM or PBSC could be safely used as allograft sources for haploidentical transplantation with good outcomes and acceptable rates of GVHD and graft failure. Prospective randomized studies are needed to evaluate the effect of PB vs BM in haploidentical settings.     

What is the role of biosimilar G-CSF agents in hematopoietic stem cell mobilization at present?

Mobilization of hematopoietic stem cells, which has largely replaced bone marrow harvesting as a source of hematopoietic stem cells, using recombinant agents such as filgrastim or lenograstim has become a standard procedure in both patients and healthy donors prior to peripheral blood stem cell collection for autologous and allogeneic stem cell transplantation. Published literature data suggest that mobilization with recombinant granulocyte-colony stimulating factor (G-CSF) is safe and mobilization outcomes are satisfactory. In recent years, besides G-CSF originators, biosimilar G-CSF agents have been approved by the regulatory agencies for the same indications. Current data showed that by using the biosimilar G-CSF, similar results regarding safety and efficacy of hematopoietic stem cell mobilization may be achieved compared to the originator G-CSF. Although the issues such as the similarity to a licenced biological medicine, differences in manufacturing processes, the potential to cause immunogenicity, extrapolation and interchangeability of these biosimilar products are still being discussed by the scientific area, however, more experience with these agents now exists in approved endications and there seems to be no reason to expect significant differences between biosimilar G-CSF and originator G-CSF regarding their efficacy and safety in both patients and healthy donors. Also, the significant cost savings of biosimilars in real life setting may enhance the use of these agents in the future. Nonetheless, the collection of long-term follow-up data is mandatory for both patients and healthy donors, and multicentre randomized clinical trials that directly compare biosimilar G-CSF with the originator G-CSF are needed in order to allow the transplant community to make informed decisions regarding the choice of G-CSF.     

Autologous peripheral blood stem cell collections in children weighing less than 10 Kg with solid tumors: experience of a single center

There have only been a few reports and limited performance of peripheral blood stem cell (PBSC) collection in very small children weighing less than 10 kg. In this study, we intended to evaluate the safety and yield of PBSC collection, with the efficacy of PBSC transplantation (PBSCT) in the smallest children with solid tumors. From January 1998 to February 2004, 173 children underwent PBSC collection in Samsung Medical Center, Korea. Of these, 15 (8.7%) children weighed less than 10 kg and their clinical diagnoses were neuroblastoma (10 cases), rhabdoid tumor (2 cases), rhabdomyosarcoma (2 cases), and Wilms tumor (1 case). PBSCs were collected following chemotherapy plus G-CSF mobilization. The median age and weight at the time of apheresis were 15 months and 9 kg, respectively. The median number of PBSC collection procedures per case was 4 (range, 2-7). The median cell yield per apheresis product was 0.95 (range, 0.01-33.32) x 10(6)/kg CD34+ cells and 1.96 (range, 0.12-23.39) x 10(8)/kg mononuclear cells. No complications associated with citrate toxicity and other adverse effect were observed during the procedures. After high-dose chemotherapy, 14 patients were reinfused with PBSCs alone and all showed successful hematopoietic recovery. We concluded that PBSC collection would be a safe and practical procedure, even when done in the smallest children, provided that adequate intravascular fluid volume and circulating red cell mass were maintained. Also, the use of PBSCs to support high-dose chemotherapy was well tolerated and might enhance hematological recovery in the smallest children showing the excellent efficacy of PBSCT.     

Validation of short‐term handling and storage conditions for marrow and peripheral blood stem cell products

BACKGROUND: Allogeneic hematopoietic stem cell transplants from unrelated donors are routinely used in the treatment of patients with hematologic malignancies. These cellular products are often collected off‐site and require transport from the collection site to transplantation centers. However, the effects of transport conditions and media on stem cell graft composition during short‐term storage have not been well described. STUDY DESIGN AND METHODS: Five bone marrow (BM), four filgrastim‐mobilized peripheral blood stem cell (PBSC), and four nonmobilized peripheral blood mononuclear cell (PBMNC) products were collected from healthy volunteer donors and stored at 4 or 20°C for up to 72 hours in 10% PlasmaLyte A plus anticoagulants such as 10% acid citrate dextran‐A (ACD‐A) and/or 10 IU/mL heparin. Products were evaluated at 0, 24, 48, and 72 hours for cellular content, viability, and metabolic activities. RESULTS: BM products maintained equivalent cell viability when stored at either 4 or 20°C over 72 hours, but cell viability was better maintained for PBSC products stored at 4°C. The mean viable CD34+ cell recovery for PBSC and BM products stored over 72 hours at 4°C was higher than 75%. Significantly lower CD34+ cell and colony‐forming unit recoveries were seen in PBSC products but not BM products stored at room temperature. Faster lactic acid accumulation was observed in PBMNC and PBSC products stored without ACD‐A. CONCLUSIONS: Seventy‐two‐hour storage of BM, PBSC, and PBMNC products at refrigerated temperature maintains optimal cell viability and recovery. Anticoagulation with ACD‐A is preferred over heparin to reduce lactic acid accumulation in the product media.     

Optimizing pediatric peripheral blood stem cell collection

IntroductionPediatric PBSC harvests pose specific challenges during apheresis and a knowledge of the same and variables affecting PBSC collection are very important in planning these procedures. In the present study safety profile of pediatric PBSC procedures and variables influencing the successful collection were analyzed.MethodPediatric PBSC harvest data for 3 years was reviewed for donor, procedural and product parameters and any specific challenges faced during the procedures. Successful PBSC collection was defined when CD34 dose obtained was ≥2 × 10⁶ cells/Kg of recipients’ body weight.Results85 PBSC collections performed on 46 children (age range 1.5–15 years) were included. Sixty-two procedures were on autologous donors and 23 on allogenic donors. The median CD34+ cell dose in the PBSC product per procedure was 2.12 × 10⁶ cells/Kg for autologous procedures and 4.6 × 10⁶ cells/Kg for allogenic procedures. Systemic adverse reaction was observed during only one procedure (0.01 %) and was managed conservatively. Successful dose was collected in 52 procedures (61.17 %) and was significantly associated with CD34+ count of more than 19.7/μL, monocyte count of more than 1.65 × 10⁶/μL, allogenic collection and female gender (p = 0.00001, p = 0.011, p = 0.00052, and p = 0.0001, respectively).ConclusionPBSC collection is safe in pediatric age groups and pre-procedure CD34 count of ≥20/μL on the day of collection may result in successful collection of stem cell dose. It is important to identify factors associated with failed collection for appropriate counselling and justifying pre-emptive use of stem cell mobilizing agents.     

Factors affecting hematopoietic stem cell mobilization and apheresis in allogeneic donors: The role of iron status

Infused CD34 cell count has a significant impact on transplant outcome. In this retrospective study, we aimed to analyze the impact of donor iron parameters on peripheral blood stem cell (PBSC) collection. A total of 303 related donors were included in the study. The mobilization regimen, recombinant G-CSF, was given for four consecutive days. A CD34⁺ cell count below 2 × 10⁶/kg was defined as mobilization failure which was demonstrated in 23 donors (7.6%). Mobilization failure was more frequent in female donors than male donors (13.7% vs 3.4%). Body mass index, mean corpuscular volume, hemoglobin and ferritin levels were found to be lower in donors with mobilization failure. Body mass index was significantly correlated with PBSC count on the 4th day of G-CSF. Body mass index, male gender, mean corpuscular volume and ferritin levels had significant impact on PBSC count. Although PBSC count was found to be similar between female and male donors, female gender was shown to have an adverse impact on PBSC collection, which may be attributed to lower body weight and concurrent iron deficiency.     

恶性血液系统疾病自体外周血造血干细胞动员的临床分析

目的:分析恶性血液系统疾病患者外周血造血干细胞动员与采集过程中的影响因素。方法:对50例血液系统恶性疾病患者在东南大学附属中大医院血液科进行外周血造血干细胞动员。对患者年龄、性别、动员方案、疾病状态、采集机器等因素进行分析,评估以上因素对干细胞动员结果的影响,并分析了采集前白细胞、血红蛋白、血小板的数量与采集的CD34^+细胞计数的相关性。结果:动员方案对CD34^+细胞采集数及CD34^+细胞采集成功率的影响有显著性影响,而性别、年龄、确诊到动员间隔时间、既往化疗方案、骨髓受累与否等对干细胞采集数量影响并不显著。采集前外周血白细胞数量及血红蛋白数量与采集的CD34^+细胞数呈正相关。采集前外周血中白细胞计数及单个核细胞计数与采集成功密切相关。结论:化疗联合细胞因子的动员方案采集造血干细胞优于单用细胞因子的动员方案。通过采集前白细胞计数及单个核细胞计数确定合适的采集时机,可以提高采集的成功率。     

Technical and safety aspects of blood and marrow transplantation using G-CSF mobilized family donors

An allogeneic transplantation programme using immunoselected blood progenitor and bone marrow CD34+ cells has been established. Thirteen healthy HLA-matched, MLC negative sibling donors received two doses of 5 micrograms kg-1 G-CSF (s.c. daily) for 5 days. On days 4 and 5, large-volume mononuclear cell aphereses were performed (COBE Spectra) and on day 5 one unit of autologous blood was obtained. Mononuclear cells were pooled and cryopreserved after CD34+ cell-immunoselection on day 5. Bone marrow (BM) of the same donors was procured under routine conditions 10-45 days later (median: 27 days). The final graft consisted of blood CD34+ cells with either complete BM (n = 5) or immunoselected BM CD34+ cells (n = 8). The present paper describes the progenitor cell mobilization and apheresis protocol and analyzes the cell loss by BM and peripheral blood progenitor cell (PBPC) donation. Considerably larger amounts of mononuclear cells (CD45+), T-lymphocytes (CD3+) and platelets were lost by the apheresis as compared to bone marrow without apparent immediate clinical consequences for the donors. Owing to cross-cellular contamination of the apheresis concentrate, blood platelet count (PC) significantly decreased (mean PC after the second apheresis 116 x 10 microL-1); furthermore on average 3.04 x 10(10) CD3+ cells were removed by two apheresis sessions. This loss did not lead to long-term total lymphocyte count changes (2370 microL-1 versus 1889 microL-1) as observed during the long-term follow-up of 7/13 donors (mean 290 days). Subjectively, the PBPC collections were better accepted than BM donations in all but one family donor.     

Increased risk of lethal graft-versus-host disease-like syndrome after transplantation into NOD/SCID mice of human mobilized peripheral blood stem cells, as compared to bone marrow or cord blood

We tested the ability of human cells from different hematopoietic tissues to generate graft versus host disease-like syndrome (GVHD) in sublethally irradiated non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Tissue sources of human hematopoietic cells were: (1) bone marrow (BM), (2) nonmobilized peripheral blood (PB), (3) mobilized peripheral blood stem-progenitor cells (PBSC), and (4) cord blood (CB). To avoid interindividual donor variation, part of this study was done using BM, PB, and PBSC donated by a single healthy adult volunteer. A total of 179 NOD/SCID mice received graded human hematopoietic cell doses [5-500 x 10(6) mononuclear cells (MNC), containing 2-325 x 10(6) CD3(+) T cells, per mouse] from individual donors. Mice were observed for the development of GVHD and sacrificed 60 days after transplantation (earlier if ill). Mice were analyzed quantitatively by flow cytometry for human hematopoietic cell types and histologically, especially for human T lymphocytes infiltrating BM. No mouse transplanted with the tested doses of human CB or BM cells developed GVHD (experimentally defined as >10% human T lymphocytes infiltrating the mouse BM). For PB and PBSC, the frequencies of death, death with GVHD, and GVHD were directly related to the dose and source of human cells. Because PB cells contaminate harvested BM, the results from infused BM and PB were next combined for further analysis (BM/PB). The relative risks (hazard ratios estimated from the proportional hazards model) for death with GVHD, for each 10 human T cell dose increase, were 1.15 for BM/PB (p < 0.0001) and 1.47 for PBSC (p < 0.0001). In this in vivo xenogeneic model, the average T cell from human PBSC generated GVHD more potently than did the average T cell from human BM/PB, and the average CB T cell had a much lower GVHD potential. These results suggest that the potential for clinical GVHD from an HLA-disparate donor graft is likely to be quantitatively dependent both on the total number of T lymphocytes in the donor graft and the tissue source of the graft. Quantitative criteria for optimal T cell content of allogeneic donor hematopoietic grafts from different sources are discussed.     

Induction of a hypercoagulability state and endothelial cell activation by granulocyte colony-stimulating factor in peripheral blood stem cell donors

In June, 1997, we initiated a prospective study to analyze the effect of granulocyte colony-stimulating factor (G-CSF) on coagulation system in peripheral blood stem cells (PBSC) donors following G-CSF administration. Since, 25 consecutively healthy donors received G-CSF (filgrastim) to mobilize and collect PBSC and 20 donors were finally included in the study. Blood samples were collected immediately before starting G-CSF and prior to PBSC collection to analyze the following parameters: prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, hypercoagulability markers (D-dimer, TAT complex, F1 + 2), natural anticoagulants (antithrombin, protein C, protein S), endothelial activation markers [von Willebrand factor antigen (vWF:Ag) and angiotensin converting enzyme (ACE)], and resistance to activated protein C. We found a significant increase in F1 + 2 and D-dimer while a significant decrease of antithrombin and protein C activity was evidenced. Regarding endothelial cell activation markers, a significant increase of vWF:Ag with a slightly significant decrease of ACE were also observed. Therefore, in PBSC donors receiving G-CSF our results reveal activation of both coagulation and endothelial cells that could favor the developing of thrombotic events. In consequence, a careful monitoring should be considered in those cases with risk factors for thrombosis.     

Management strategies for poor peripheral blood stem cell mobilization.

Peripheral blood stem cells (PBSC) have nearly replaced bone marrow (BM) as the preferred source of hematopoietic rescue for patients undergoing high-dose chemotherapy. However, some patients fail to mobilize sufficient numbers of PBSC into the peripheral blood thereby putting high-dose chemotherapy at risk. The present article reviews mobilization of PBSC with a special focus on poor mobilizers. Under steady-state conditions less than 0.05% of the white blood cells (WBC) are CD34+ cells. Chemotherapy results in a 5-15-fold increase of PBSC. Combining chemotherapy and growth factors increases CD34+ cells up to 6% of WBC. Several factors affect the mobilization of PBSC: age, gender, type of growth factor, dose of the growth factor and in the autologous setting patient's diagnosis, chemotherapy regimen and number of previous chemotherapy cycles or radiation. Poor mobilizers are defined as patients with less than 10 CD34+ cells/mul in the peripheral blood during mobilization. Promising approaches for those patients rely on remobilization, use of high doses of granulocyte-colony stimulating factor (G-CSF), or the combination of G-CSF and granulocyte macrophage (GM)-CSF, which successfully mobilized the majority of poor mobilizing patients. New agents such as long lasting variants of G-CSF and CXCR4 antagonists are at the horizon and studied in clinical trials as mobilizing agents. Muscle and bone pain are frequent adverse events in stem cell mobilization but are usually tolerated under the use of analgesics. Large volume apheresis (LVL) with a processed volume of more than 4-fold patient's blood volume is an approach to increase the CD34+ yield in patients with low CD34+ pre-counts resulting in higher yields of CD34+ cells for transplantation. Processing of more blood in LVL is achieved by an increase of the blood flow rate and an altered anticoagulation regimen with the occurrence of more citrate reactions.