Myelosuppressive effects of cytosine arabinoside (Ara-C) on growth factor-dependent human long-term bone marrow cultures (LTBMC)

Comprehensive biocompatibility testing of a new PMMA-HA bone cement versus conventional PMMA cement in vitro

For more than 50 years PMMA bone cements have been used in orthopaedic surgery. In this study attempts were made to show whether cultured human bone marrow cells (HBMC) show an osteogenetic response resulting in new bone formation, production of extracellular matrix (ECM) and cell differentiation when they were cultured onto polymerized polymethylmethacrylate (PMMA)-hydroxyapatite (HA), conventional PMMA bone cement being taken as reference. Biocompatibility parameters were collagen-I and -II synthesis, the detection of the osteoblast markers alkaline phosphatase (ALP) and osteocalcin, the number of adherent cells and the cytodifferentiation of immunocompetent cells. Cement surface structure, HA stability in culture medium and chemical element analysis of specimens were considered. Fresh marrow cells were obtained from the human femora during hip replacement. Incubation time was up to ten weeks. We used atomic forced microscopy (AFM) and scanning electron microscopy (SEM) for cement specimen analysis. Fluorescent activated cell sorter (FACS), immunohistochemical staining. SEM and light microscopy (LM) served us to judge the cellular morphology. Products of the extracellular matrix were analyzed by protein dot blot analysis, SEM energy dispersive X-ray analysis (SEM-EDX) and Ca2+/PO(4)3- detection. HA particles increased the osteogenetic potential of PMMA bone cement regarding the cellular production of collagen, alkaline phosphatase (AP), the number of osteoblasts and the cellular differentiation pattern in vitro. Both tested cements showed good biocompatibility in a human long-term bone marrow cell-culture system.

Cryopreservation of the bone marrow from patients with acute myeloid leukaemia leads to functional abnormalities

We compared the performance of the stroma (SL) and haematopoietic progenitors before (group A) or following cryopreservation from patients in complete remission (CR) of acute myeloid leukaemia before autologous transplantation (AML) (group B), to similarly treated normal cells (groups A and B). From each group, fibroblastic (F) colony-forming units (CFU) and SL were established and their growth quantitated. Upon confluence of SL, 1 x 10(4)selected CD34+ cells from patient or control samples (of group A and B) were seeded on pre-formed SL from AML or control group A and B layers and adhesive precursors were scored for the formation of blastic (-b1) CFU (>20 cells). Lastly, CD34+ cells from the 4 progenitor sources were cultured in the presence of growth factors and scored for the production of granulocyte-macrophage (GM) CFU, erythroid burst forming units (BFU-E) and mixed colonies (CFU-MIX). In the patients, CFU-F numbers were decreased and by 5 wk SL failed to reach confluence. Group A AML CD34+ progenitors gave a mean of 119.2 (SD 80.4) CFU-bl/10(4) CD34+ cells, but following cryopreservation these numbers declined (83.2, SD 72.71; p = 0.009). Although AML SL prior to cryopreservation supported control CFU-bl adequately, contrary to the norm, this property decreased in group B stroma (mean 50.9/10(4)CD34+ cells, SD 49.33; p =(0.02). Group B AML samples gave significantly fewer CFU-MIX and BFU-E than pre-freezing cultures and than control samples at the first 2-growth factor combination but numbers improved following further addition of cytokines. We conclude that cryopreservation of the bone marrow of patients in CR of AML results in an inhibition of the proliferation of the CD34+ precursors. It also modifies the stroma, leading to reductions in the support of normal clones.