Bone marrow stroma in humans: anti-nerve growth factor receptor antibodies selectively stain reticular cells in vivo and in vitro

Abstract

Two anti-nerve growth factor receptor (LNGFR or p75NGFR) antibodies, Me20.4 and Me8211, label stromal cells with dendritic features in fresh smears and in formalin-fixed, paraffin-embedded human bone marrow (BM). The LNGFR+ cells have an oval nucleus, a scanty cytoplasm with long dendrites that intermingle with the hematopoietic cells, line the abluminal side of sinus endothelial cells, and provide the scaffold for the hematopoietic marrow. At the electron microscopy level, the immunogold tag labels the body and the long branching dendrites of fibroblast-like cells with scanty cytoplasm containing mitochondria, endoplasmic reticulum, and dense bodies. The LNGFR+ cells are positive for alkaline phosphatase, reticulin, collagen III, vimentin, TE-7, and CD13 but negative for endothelial (vWF, CD34, Pal-E), neural (CD56, neurofilament) and leukocyte markers (CD45, CD68). The LNGFR+ stromal cells appear in the fetal BM before the hematopoietic activity begins, originate from the vessel adventitia, and radiate in the Bm cavity. Long-term BM culture (LTBMC) in vitro contain LNGFR+ stromal cells. We document the presence of RNA message for the low- (LNGFR) and the high- affinity NGF receptor (NTRK1) by using RT-PCR on fresh BM aspirate and on LTBMC. BM biopsies from patients with hematologic fibrogenic diseases and in cytokine-treated cancer patients are evaluated for LNGFR+ cells: the amount of stained cells is correlated with the traditional reticulin stain in cases of myelofibrosis, therapy-related myelodysplasia, leukemia, and detected an increase of stromal cells in cytokine-treated patients. The anti-LNGFR antibodies represent a specific membrane marker for the adventitial reticular cells (ARC) of the human marrow and allow precise evaluation and quantitation of this important BM microenvironment component in vivo and in vitro.

Lentiviral shRNA silencing of BDNF inhibits in vivo multiple myeloma growth and angiogenesis via down‐regulated stroma‐derived VEGF expression in the bone marrow milieu

“…Our findings corroborate previous reports demonstrating that BMSCs isolated from healthy donors express BDNF high affinity receptor TrkB, indicating that paracrine BDNF signaling in the marrow microenvironment may occur. ( 16–18 ) The data suggested that the addition of BDNF can stimulate VEGF secretion by BMSC, and this effect can be blocked by K252α, which is an specific inhibitor of TrkB. We further detected VEGF secretion by MM cell lines and BMSCs isolated from healthy donors.…”

“…Besides its frequent expression by malignant plasma cells, TrkB was found to be expressed by osteoblasts, endothelial cells, and BMSCs in the BM microenvironment. ( 16–18 ) Since BDNF and its receptor TrkB expressed by MM cells contribute to plasma cell survival, TrkB expressed by BMSCs may allow stroma–myeloma cell interaction, further influencing BM angiogenesis via secreting angiogenic cytokines. In addition, studies of our group found that the increased serum BDNF levels detected in patients with MM correlated with disease activity and serum VEGF levels.…”

Bone marrow fibrosis: pathophysiology and clinical significance of increased bone marrow stromal fibres

“…The bone marrow stromal microenvironment is composed of cells, structural fibrils and extracellular matrix (‘ground substance’). The cellular components include macrophages, fibroblastic cells (including several types of adventitial and reticular cells), adipocytes and endothelial cells, as well as other less well characterized cells (Weiss & Chen, 1975; Watanabe, 1985; Cattoretti et al , 1993). The most common structural fibrils in the bone marrow are collagen, reticulin, laminin and fibronectin (Bentley et al , 1981; Reilly et al , 1985; Cattoretti et al , 1993).…”

Establishment of a human preadipose cell line, HPB‐AML‐I: Refractory to PPARγ‐mediated adipogenic stimulation

“…Although CD15, CD33, CD34, and CD13 are known to be the most common antigens expressed in M1 patients (Foon and Todd, 1986), there are reports describing the expression of CD13 on various non‐hematopoietic cells, including epithelial cells from renal proximal tubules and intestinal brush border, endothelial cells, fibroblasts, brain cells, and bone MSC (Look et al, 1986). Furthermore, detailed immuno‐EM characterization of human bone MSC revealed the expression of CD13 as well as the nerve growth factor receptor (NGFR), alkaline phosphatase, reticulin, collagen III, and vimentin (Cattoretti et al, 1993). In this study, the high expression of CD13 in AML‐I cells does not exclude the possibility of a myeloid cell origin for AML‐I cells, but a defect in the expression of other leukemia‐associated antigens strongly support the idea of a mesenchymal origin for AML‐I cells rather than a hematopoietic origin.…”