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

Sensitivity of mesenchymal stem cells and their progeny to medicines used for the treatment of hematoproliferative diseases

BACKGROUND/AIMS

The influence of cytostatic medicines on mesenchymal stem cells (MSC) and their progeny, fibroblastic colony-forming units (CFU-F), was investigated.

METHODS

Mice were treated with busulfan, cyclophosphamide, cytarabine, methotrexate and bortezomib, as used in clinical practice. MSC and CFU-F were analyzed 3 days and 6 weeks after the treatment termination. To estimate MSC numbers, the ectopic foci formation method was used. Briefly, a donor bone marrow plug was transplanted under the renal capsule of a syngeneic animal, leading to ectopic foci formation. The systemic response of the hematopoietic microenvironment to these drugs was studied using the same method applied to recipients pretreated with the medicines.

RESULTS

CFU-F concentration was halved in the bone marrow of mice treated with busulfan, methotrexate and cyclophosphamide, and was not restored for the next 6 weeks. Proliferative potential and differentiation abilities of MSC were not affected by these medicines. The enlargement of foci size in mice treated with cytostatic agents was not conditioned by MSC, but by more mature stromal precursor cells.

CONCLUSIONS

Cytostatic medicines affect stromal precursors in 2 ways: they decrease CFU-F concentration in the 'steady-state' bone marrow, while stimulating growth of the stromal microenvironment during its de novo formation. MSC are not sensitive to the cytostatic agents used.

Basic fibroblast growth factor corrects proliferative derangement of bone marrow stroma and CD34(+) population following allogeneic stem cell transplantation

OBJECTIVE

Following stem cell transplantation (SCT), the integrity of the hematopoietic microenvironment is important for the recovery of bone marrow. We studied the effects of basic fibroblast growth factor (bFGF) on the proliferation of clonogenic progenitors and bone marrow stroma from patients receiving cytokine-mobilized allogeneic stem cell transplants (SCT).

MATERIALS AND METHODS

Patient bone marrow mononuclear cells were studied at a minimum of 6 months after transplantation. Control and patient samples were divided into two fractions, one to establish the adherent stroma layers (SL) and the other to select for the progenitor population. SL from normal subjects or from patients were supplemented with 0 (control), 2, or 20 ng/mL bFGF in combination with heparan sulfate, and the resulting area of the dish covered by stroma was quantitated in each group. At 3 weeks of culture, a monocellular suspension was prepared by exposing SL to 0.1% trypsin. Cells then were cultured in the colony-forming unit fibroblast (CFU-F) assay, which was supplemented with 0 (control), 2, or 20 ng/mL bFGF. With the second fraction, CD34(+) cells were selected with paramagnetic beads, and 1 x 10(4) cells were incubated in cross-culture studies on preformed SL from patient or control origin (with or without the addition of bFGF). SL adherent CD34(+) cells were covered with agar and cultured for 6 days. Aggregates of >20 cells were scored as blastic colonies (CFU-bl).

RESULTS

At 3 weeks of culture, the median surface area of dishes covered by monoloayers from 13 patients was 40% (range 10-50% vs normal 55%, range 30-60%; p = 0.00006) and improved significantly, matching control values, in dishes supplemented with bFGF. Addition of bFGF to stroma monolayers had no effect on the number of CFU-F in both patient and control samples. Selected CD34(+) cells from patients receiving transplants and cultured on normal stroma gave significantly fewer CFU-bl than control samples (median 36, range 3-121 vs 147, range 10-184; p = 0.006), but colony numbers corrected following exposure to bFGF. Normal CD34(+) cells proliferated poorly on stroma from patients (median CFU-bl 37.5, range 6-84; p = 0.02), but also expanded significantly following bFGF supplementation (104, range 6-117; p = 0.001).

CONCLUSIONS

Following SCT, poor SL and CD34(+) proliferation can be corrected by addition of bFGF.

Increased apoptosis of bone marrow cells and preserved proliferative capacity of selected progenitors predict for clinical response to anti-inflammatory therapy in myelodysplastic syndromes

To determine the relation of apoptosis and clonal proliferation in the bone marrow (BM) to the effectiveness of a therapeutic protocol described to downmodulate monokine activity in patients with myelodysplastic syndromes (MDS). Prior to protocol therapy, BM stroma was cultivated and selected CD34(+) cells were studied in stroma and cytokine-dependent clonogenic assays. The TUNEL assay was used to establish the degree of apoptosis occurring in the marrow and CD34(+) population. The effectiveness of oral ciproloxacin 500 mg b. i.d., pentoxifylline 800 mg t.i.d., and dexamathasone 4 mg t.i.d. (CPD) antiinflammatory therapy was correlated with the intensity of cell apoptosis and proliferation of BM progenitor cells. Seventeen patients were studied. Twelve patients (10 transfusion dependent) received therapy for a median of 99 days (range 49-284). Toxicity caused four patients to discontinue the drug combination. Six patients fulfilled response criteria. Four patients became transfusion independent, and 50% reduction in the need for blood transfusions was noted in one patient. Blood parameters of one untransfused patient increased by >30%. Blood count remained unsupported in three patients, even at a median of 12 months after trial discontinuation. Apoptosis of marrow cells and selected CD34(+) progenitors was detected in a median of 49.5% (range 3. 6%-90%) and 10.6% (range 3.6%-100%; p < 0.01), respectively. In patients who responded to therapy, the median apoptosis rate in the bone marrow population was 71%, in contrast to the nonresponder's rate of 13% (p = 0.002). Overall clonogenic growth of selected precursors corresponded significantly with response to CPD protocol (p = 0.004). In some patients with MDS, ineffective hematopoiesis is related to high apoptotic index despite proliferation of the CD34(+) precursors. These patients seem to benefit from CPD cytokine modulatory therapeutic strategy.

Immune reconstitution after allogeneic bone marrow transplantation depleted of T cells

BACKGROUND

Immune reconstitution following transplantation in individuals who had received T-cell-depleted marrow from HLA identical siblings was serially documented and correlated with the clinical recovery.

METHODS

Patients were preconditioned with radiation containing programs. GvHD prophylaxis was by T-cell depletion with CAMPATH 1G (ex vivo; median dose 20 mg). After transplantation lymphoid development was studied by flow cytometry and serum Ig concentrations were determined. Charts were reviewed to determine the effects of the immune reconstitution on the clinical performance.

RESULTS

The mean donor mononuclear cell number infused was 0.89x10(8)/kg. Within 6 months all the patients recovered their blood parameters and only one required therapy for GvHD. However, despite normal blood counts, 15 suffered life-threatening opportunistic infections, developing at a median of 24 weeks post grafting, but occurring even after 11 months. At 8 weeks from marrow infusion when leukocyte values had normalized in 15/20, compared to normal, immunophenotyping of blood cells from BMT revealed a significantly reduced mean lymphocyte count (1.06, SD 0.83x10(9)/l; P = 0.01), cells expressing CD3 (0.7x10(9)/l, SD 0.68; P = 0.05), CD4 (0.13x10(9)/l, SD 0.21; P = 0.0001) and CD19 (0.04x10(9)/l, SD 0.05; P = 0.001). Populations expressing CD8 and CD56 remained within normal range throughout the study. Normalization of cell numbers displaying CD2, CD3 and CD19 was delayed until 52, 52 and 24 weeks respectively, while CD4 counts persisted subnormal even at 72 weeks. Serum IgA levels were significantly decreased for the entire study period.

CONCLUSIONS

T-cell depletion with CAMPATH 1G while effectively preventing GvHD, also causes clinically significant and prolonged immunosuppression with apparently important clinical implications.