Association between an Impaired Bone Marrow Vascular Microenvironment and Prolonged Isolated Thrombocytopenia after Allogeneic Hematopoietic Stem Cell Transplantation

Abstract

Prolonged isolated thrombocytopenia (PT) is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, it remains unclear whether abnormalities of the bone marrow (BM) microenvironment are involved in the pathogenesis of PT. This prospective, nested case-control study included 20 patients with PT, 40 matched patients with good graft function (GGF) after allo-HSCT, and 16 healthy donors (HDs). Cellular elements of the BM microenvironment, including BM endothelial cells (BMECs), perivascular cells, and endosteal cells, were analyzed via flow cytometry and via hematoxylin-eosin and immunohistochemical staining in situ. Moreover, stromal-derived factor 1 (SDF-1) and vascular endothelial growth factor (VEGF) were measured in the plasma of BM via an enzyme-linked immunosorbent assay. No significant differences in endosteal cells (15 per high-power field [hpf] versus 16 per hpf versus 20 per hpf, P > .05) were demonstrated among the patients with PT, GGF, and the HDs. The PT patients exhibited remarkable decreases in cellular elements of the vascular microenvironment, including BMECs (.01% versus .18% versus .20%, P < .0001) and perivascular cells (.01% versus .12% versus .13%, P < .0001), compared with the GGF allo-HSCT recipients and the HDs, respectively. Moreover, significantly lower levels of SDF-1 (3163 pg/mL versus 3928 pg/mL, P = .0002) and VEGF (56 pg/mL versus 123 pg/mL, P < .0001) were found in the BM plasma of the PT patients compared with the BM of the GGF patients. A multivariate analysis revealed that BMECs (odds ratio [OR] = 171.57, P = .002) and cytomegalovirus infection after HSCT (OR = 4.35, P = .009) were independent risk factors for PT. Our data suggested that an impaired BM vascular microenvironment and megakaryocyte-active factors may contribute to the occurrence of PT after HSCT.

The bone marrow microenvironment is similarly impaired in allogeneic hematopoietic stem cell transplantation patients with early and late poor graft function

“…The gating strategies used for perivascular cells and bone marrow endothelial cells were previously reported 2,15 and are shown in Figure 1. An aliquot of 5 ml of fresh bone marrow was stained with mouse antihuman CD146-PE/CD34-PECy7/CD45-V500/vascular endothelial growth factor receptor 2 (VEGFR2) Alexa fluor 647-conjugated monoclonal antibodies (Becton Dickinson, San Jose, CA, USA).…”

“…Immune histochemistry staining was performed using rabbit anti-human osteopontin, CD34 and CD146 primary antibodies (Abcam, Cambridge, MA, USA) as previously described. 2,15 The slides were read blindly by two observers. Each section was analyzed using light microscopy (Axiovert 200; Carl Zeiss, Jena, Germany).…”

“…Bone marrow cellularity was categorized into three groups. 2,15 Endosteal cells were scored as numbers of osteopontinpositive cells on the line of trabecular bone per high-power field. Numbers of CD146-positive perivascular cells per microvessel were enumerated.…”

“…[11][12][13][14] We recently reported abnormalities of the bone marrow microenvironment in transplant recipients with late PGF 2 and prolonged isolated thrombocytopenia. 15 Our previous data suggest that an impaired bone marrow microenvironment may contribute to the occurrence of different degrees of delayed hematopoietic reconstitution after allo-HSCT. Thus, we speculate that the occurrence of early PGF may also be associated with a defective bone marrow microenvironment.…”

Haploidentical, unmanipulated G-CSF-primed peripheral blood stem cell transplantation for high-risk hematologic malignancies: an update

“…The delay in platelet recovery or prolonged isolated thrombocytopenia remains the main problem of hematopoietic reconstitution after unmanipulated haplo-HCT. 19 Although its mechanism is not clear, choosing a younger donor from the haploidentical family members should be preferred. 20 In allo-HCT from matched sibling donors, trials have shown a significantly higher incidence of acute GvHD grade 2-4, 6,7 chronic GvHD and extensive chronic GvHD 6,20 in PBSC recipients compared with BM recipients.…”