The hematopoietic defect in aplastic anemia assessed by long-term marrow culture

Abstract

Thirty-two patients with aplastic anemia (AA) have been studied using the long-term bone marrow culture (LTBMC) system. Of these patients, 26 had been treated with immunosuppressive therapy including antilymphocyte globulin (ALG) with or without androgens or high-dose methyl prednisolone. The remaining six patients either required no treatment or were studied before therapy was begun. Thirty-one of 32 patients (96%) had defective hematopoiesis in LTBMC with little or no evidence for the generation of primitive progenitor cells. The only exception was a patient with spontaneous recovery of aplasia in whom the defect was less marked. Crossover LTBMC experiments were performed in 23 cases by inoculating (1) patient marrow hematopoietic cells that had been depleted of adherent cells onto preformed, irradiated, normal stromas to assess the proliferative capacity of the hematopoietic cells, and (2) normal marrow hematopoietic cells that were depleted of adherent cells onto preformed, irradiated stromas from patients with AA to assess stromal function. Results of these experiments demonstrated a hematopoietic defect in all patients that was independent of the degree of hematologic recovery after ALG therapy. Only one patient had a probable stromal defect and this coexisted with a defect in the regenerative capacity of hematopoietic cells. We conclude that LTBMC is a sensitive method for detecting and defining the hematopoietic failure in AA. We suggest that the defective hematopoiesis present in all patients studied may be important in the pathogenesis of clonal evolution in AA.

Pesticide induced alterations in marrow physiology and depletion of stem and stromal progenitor population: An experimental model to study the toxic effects of pesticide

“…The long‐term bone marrow culture system has proved to be a useful tool for the characterization of hematopoietic microenvironment in‐vitro . Pesticide exposure resulted in disorders with disturbed or impaired stroma which contribute to abnormal hematopoiesis (Bentley et al, ; Lenon and Micklem, ; Marsh et al, ). Results from our studies clearly demonstrated the deranged explant growth pattern with frequent appearance of giant adipogenic precursors and concomitant irregularities of stromal development and appearance of “immature stromal precursors” (toxicity induced inhibition of maturation) in the pesticide‐induced group compared to the normal.…”

Advances in understanding the pathogenesis of acquired aplastic anaemia

“…In experimental animals, where HSCs can be quantified by in vivo assay, it has been amply demonstrated that the shortage of stem cells is associated with AA (Scheinberg & Chen, ). In humans, the closest surrogate of HSCs are the so–called long‐term culture initiating cells (LTC‐IC): their numbers in the peripheral blood and in the bone marrow of patients with AA are drastically reduced (Fig B; Marsh et al , ; Maciejewski et al , ). CD34+ cells are also decreased in AA (Maciejewski et al , ; Manz et al , ).…”

Association of an Impaired Bone Marrow Microenvironment with Secondary Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation

“…The hematopoietic supporting function of BM stromal cells has been shown to be impaired before autologous peripheral blood stem cell transplantation (auto-PBSCT) [15,16] and even 1 year after auto-PBSCT [17]. Moreover, stromal defects also have been reported in recipients of allo-HSCT and patients with aplastic anemia using similar methods [18][19][20]. However, LTBMC typically results in confluent layers of adherent cells composed of a heterogeneous population of stromal cells including fibroblasts, endothelial cells, adipocytes, and other types [19].…”