Myogenic commitment of human stem cells by myoblasts Co-culture: a static vs. a dynamic approach.

An in-vitro model of human bone marrow mesenchymal stem cells (hBM-MSCs) myogenic commitment by synergic effect of a differentiation media coupled with human primary skeletal myoblasts (hSkMs) co-culture was developed adopting both conventional static co-seeding and perfused culture systems. Static co-seeding provided a notable outcome in terms of gene expression with a significant increase of Desmin (141-fold) and Myosin heavy chain II (MYH2, 32-fold) at day 21, clearly detected also by semi-quantitative immunofluorescence. Under perfusion conditions, myogenic induction ability of hSkMs on hBM-MSCs was exerted by paracrine effect with an excellent gene overexpression and immunofluorescence detection of MYH2 protein; furthermore, due to the dynamic cell culture in separate wells, western blot data were acquired confirming a successful cell commitment at day 14. A significant increase of anti-inflammatory cytokine gene expression, including IL-10 and IL-4 (15-fold and 11-fold, respectively) at day 14, with respect to the pro-inflammatory cytokines IL-12A (7-fold at day 21) and IL-1ß (1.4-fold at day 7) was also detected during dynamic culture, confirming the immunomodulatory activity of hBM-MSCs along with commitment events. The present study opens interesting perspectives on the use of dynamic culture based on perfusion as a versatile tool to study myogenic events and paracrine cross-talk compared to the simple co-seeding static culture.

A Case Series of Blastic Plasmacytoid Dendritic Cell Neoplasia.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), an extremely rare and aggressive tumor, derives from plasmacytoid dendritic cell precursors and is characterized by CD4 and CD56 positivity accompanied by the expression of isolated myeloid, B- or T-cell lineage markers. Despite the recent introduction of specific targeted therapies, prognosis is still poor with a median overall survival of one year, and allogeneic bone marrow transplantation remains the only curative treatment in eligible patients. In this series, we described two cases of adult BPDCN treated with high dose cytarabine and methotrexate and autologous hematopoietic stem cell transplantation, or fludarabine, cytarabine, and idarubicin achieving the first a complete lasting remission, while the second only a transient improvement in skin lesions.

In Vitro Apoptotic Effects of Farnesyltransferase blockade in Acute Myeloid Leukemia Cells.

Farnesyltransferase inhibitors (FTIs) are a class of oral anti-cancer drugs currently tested in phase I-II clinical trials for treatment of hematological malignancies. The in vitro effects of various FTIs (alpha-hydroxyfarnesylphosphonic acid, manumycin-A and SCH66336) were tested on CD34+ KG1a cell line and in primary acute myeloid leukemia (AML) cells from 64 patients. By cell viability and clonogeneic methylcellulose assays, FTIs showed a significant inhibitory activity in CD34+ KG1a and primary bone marrow (BM) leukemic cells from 56% of AML patients. FTIs also induced activation of caspase-3 and Fas-independent apoptosis, confirmed by the finding that inhibition of caspase-8 was not associated with the rescue of FTI-treated cells. We concluded that other cellular events induced by FTIs may trigger activation of caspase-3 and subsequent apoptosis, but the expression of proapoptotic molecules, as Bcl-2 and Bcl-XL, and antiapoptotic, as Bcl-X(s), were not modified by FTIs. By contrast, expression of inducible nitric oxide synthase (iNOS) was increased in FTI-treated AML cells. Our results suggest a very complex mechanism of action of FTIs that require more studies for a better clinical use of the drugs alone or in combination in the treatment of hematological malignancies.

Prolonged complete hematologic response in relapsed/refractory T-large granular lymphocyte leukemia after bendamustine treatment.

T-large granular lymphocyte leukemia (T-LGLL) is a chronic clonal proliferation of effector memory cytotoxic CD3+CD57+CD56- T cells and the current guidelines suggest immunosuppressive therapy as first-line therapy, but the treatment of refractory/relapsed patients is still challenging due to the lack of prospective studies. We describe a series of two refractory/relapsed T-LGLL patients successfully treated with bendamustine, a chemotherapeutic agent largely used for B-cell neoplasms, but poorly investigated for the treatment of T-cell diseases. Complete remission (CR) was achieved in 3 and 6 months, respectively, and maintained for at least 20 months. One patient relapsed after a 20-month CR, but she was responsive to bendamustine therapy again, obtaining a further prolonged CR. Bendamustine as single agent or in combination could be a feasible therapeutic option in refractory/relapsed T-LGLL, especially for elderly patients because of its safety profile.

Alemtuzumab plus cyclosporine treatment of the autoimmune hemolytic anemia in an adult bowel transplant.

An adult male underwent a bowel transplant for tufting enteropathy, receiving alemtuzumab, tacrolimus, and steroids as immunosuppressants. Five years later, he developed an autoimmune hemolytic anemia (AIHA), anti-IgG positive, with reduced reticulocyte count, leukopenia, and thrombocytopenia with antiplatelet antibodies. After an unsuccessful initial treatment with high dose steroids, reduction in tacrolimus dose, and intravenous immunoglobulin (IVIG), a bone marrow biopsy revealed absence of erythroid maturation with precursor hyperplasia. The patient was switched to sirolimus and received four doses of rituximab plus two courses of plasmapheresis, which decreased his transfusion requirements. After a febrile episode one month later, the AIHA relapsed with corresponding decreases in platelet and leukocyte count: cyclosporine A (CsA) was started with a second course of rituximab and IVIG without response, even though repeat bone marrow biopsy did not reveal morphology correlated to an acquired pure red cell aplasia (APRCA). Considering the similarity in his clinical and laboratory findings to APRCA, alemtuzumab was added (three doses over a week) with CsA followed by steroids. The patient was eventually discharged transfusion-independent, with increasing hemoglobin (Hb) levels and normal platelet and leukocyte count. One year later he is still disease-free with functioning graft.

Immunological derangement in hypocellular myelodysplastic syndromes.

Hypocellular or hypoplastic myelodysplastic syndromes (HMDS) are a distinct subgroup accounting for 10-15% of all MDS patients, that are characterized by the presence of bone marrow (BM) hypocellularity, various degree of dysmyelopoiesis and sometimes abnormal karyotype. Laboratory and clinical evidence suggest that HMDS share several immune-mediated pathogenic mechanisms with acquired idiopathic aplastic anemia (AA). Different immune-mediated mechanisms have been documented in the damage of marrow hematopoietic progenitors occurring in HMDS; they include oligoclonal expansion of cytotoxic T lymphocytes (CTLs), polyclonal expansion of various subtypes of T helper lymphocytes, overexpression of FAS-L and of the TNF-related apoptosis-inducing ligand (TRAIL), underexpression of Flice-like inhibitory protein long isoform (FLIPL) in marrow cells as well as higher release of Th1 cytokines, such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). It has also been documented that some HMDS patients have higher frequency of polymorphisms linked both to high production of proinflammatory cytokines such as TNF-α and transforming growth factor-ß and to the inhibition of T-cell mediated immune responses such as interleukin-10, further suggesting that immune-mediated mechanisms similar to those seen in AA patients may also operate in HMDS. Clinically, the strongest evidence for immune-mediated hematopoietic suppression in some HMDS is the response to immunosuppression including mainly cyclosporine, anti-thymocyte globulin and/or cyclosporine, or alemtuzumab. Here we review all these immune mechanisms as well as the influence of this deranged cellular and humoral immunologic mileau on the initiation and possible progression of MDS. All these observations are pivotal not only for a better understanding of MDS pathophysiology, but also for their immediate clinical implications, eventually leading to the identification of MDS patients who may benefit from immunosuppression.

OPSI threat in hematological patients.

Overwhelming post-splenectomy infection (OPSI) is a rare medical emergency, mainly caused by encapsulated bacteria, shortly progressing from a mild flu-like syndrome to a fulminant, potentially fatal, sepsis. The risk of OPSI is higher in children and in patients with underlying benign or malignant hematological disorders. We retrospectively assessed OPSI magnitude in a high risk cohort of 162 adult splenectomized patients with malignant (19%) and non malignant (81%) hematological diseases, over a 25-year period: 59 of them splenectomized after immunization against encapsulated bacteria, and 103, splenectomized in the previous 12-year study, receiving only life-long oral penicillin prophylaxis. The influence of splenectomy on the immune system, as well as the incidence, diagnosis, risk factors, preventive measures and management of OPSI are also outlined. OPSI occurred in 7 patients (4%) with a median age of 37 years at time interval from splenectomy ranging from 10 days to 12 years. All OPSIs occurred in non immunized patients, except one fatal Staphylococcus aureus -mediated OPSI in a patient adequately immunized before splenectomy. Our analysis further provides evidence that OPSI is a lifelong risk and that current immune prophylaxis significantly decreases OPSI development. Improvement in patients' education about long-term risk of OPSI and increased physician awareness to face a potentially lethal medical emergency, according to the current surviving sepsis guidelines, represent mandatory strategies for preventing and managing OPSI appropriately.

Accelerated bone mass senescence after hematopoietic stem cell transplantation.

Osteoporosis and avascular necrosis (AVN) are long-lasting and debilitating complications of hematopoietic stem cell transplantation (HSCT). We describe the magnitude of bone loss, AVN and impairment in osteogenic cell compartment following autologous (auto) and allogeneic (allo) HSCT, through the retrospective bone damage revaluation of 100 (50 auto- and 50 allo-HSCT) long-term survivors up to 15 years after transplant. Current treatment options for the management of these complications are also outlined. We found that auto- and allo-HSCT recipients show accelerated bone mineral loss and micro-architectural deterioration during the first years after transplant. Bone mass density (BMD) at the lumbar spine, but not at the femur neck, may improve in some patients after HSCT, suggesting more prolonged bone damage in cortical bone. Phalangeal BMD values remained low for even more years, suggesting persistent bone micro-architectural alterations after transplant. The incidence of AVN was higher in allo-HSCT recipients compared to auto-HSCT recipients. Steroid treatment length, but not its cumulative dose was associated with a higher incidence of bone loss. Allo-HSCT recipients affected by chronic graft versus host disease seem to be at greater risk of continuous bone loss and AVN development. Reduced BMD and higher incidence of AVN was partly related to a reduced regenerating capacity of the normal marrow osteogenic cell compartment. Our results suggest that all patients after auto-HSCT and allo-HSCT should be evaluated for their bone status and treated with anti-resorptive therapy as soon as abnormalities are detected.

Low-dose valgancyclovir as cytomegalovirus reactivation prophylaxis in allogeneic haematopoietic stem cell transplantation.

The efficacy and safety of low dose oral valgancyclovir (VGCV) as cytomegalovirus (CMV) reactivation prophylaxis was retrospectively evaluated in 32 consecutive patients which underwent allogeneic HLA-matched related and unrelated hematopoietic stem cell transplantation (HSCT). Thirty HSCT recipients showed pretransplant CMV seropositivity. Fifteen received a myeloablative conditioning regimen, while seventeen patients received a reduced-intensity conditioning regimen. Twenty-one patients received graft-versus-host disease (GVHD) prophylaxis with cyclosporin A (CsA) and methotrexate (MTX), and the others CsA with MTX and anti-thymocyte globulin. CMV infection was monitored weekly using polymerase chain reaction (PCR). VGCV was administered orally at a dose of 450 mg daily for six months. Six patients developed a positive CMV-PCR on average 56 days after HSCT successfully treated with VGCV at 1800 mg/day, except one who developed fatal gastrointestinal CMV disease. At the time of CMV reactivation, four patients had been affected by grade II-IV acute GVHD and two by an extensive chronic GVHD. No significant specific VGCV-related toxicity was encountered. Seven patients presented hematological toxicity which did not require drug discontinuation. Our data suggest that low dose VGCV is safe and effective as CMV reactivation prophylaxis in allogeneic HSCT recipients. These results require further validation in prospective randomized studies.

Successful management of pulmonary mucormycosis with liposomal amphotericin B and surgery treatment: a case report.

Mucormycosis is an increasingly recognized invasive fungal infection (IFI) in patients with acute myeloid leukemia (AML) and after allogeneic (allo) stem cell transplantation (HSCT); it is mainly due to the severe and prolonged neutropenia related to high-dose chemotherapy. In such patients, the lung is the most frequently involved site in mucormycosis. Since rapidly progressive dissemination may occur after pulmonary mucormycosis in hematologic malignancies, early diagnosis and prompt initiation of an effective antifungal therapy is mandatory for a successful outcome. We report the case of a young AML patient who developed, early after the onset of neutropenia in the first induction phase of chemotherapy, a rapidly progressive pulmonary IFI, successfully treated with liposomal Amphotericin-B (LAmB) and then with a limited open toracothomy biopsy, clearly establishing diagnosis of mucormycosis and removing lung infiltrate. Secondary prophylaxis with LamB, applied during both consolidation therapy and myeloablative sibling allogeneic HSCT, was effective to prevent IFI recurrence despite the development of grade I acute graft-versus-host disease (GVHD) and limited chronic GVHD requiring immunosuppressive treatment. Our case report further provide evidence that the combined surgical and LAmB therapy is an effective and safe choice for the management of pulmonary mucormycosis in hematological immunocompromised patients.

[Proven and expected benefits of intravenous lidocaine administered during the perioperative period]. / Bénéfices démontrés et potentiels de l'administration intraveineuse périopératoire de lidocaïne.

Local anesthetics which inhibit sodium channels are used for neural blockade during infiltration and locoregional anesthesia. Furthermore lidocaine given intravenously acts on other cellular systems and produces multiple properties, some of which are beneficial during the perioperative period. Indeed, intravenous lidocaine is analgesic, antihyperalgesic, antiinflammatory, and improves the recovery of bowel function after abdominal surgery. As a consequence, lidocaine has been added to postoperative analgesic strategies. This article reviews clinically relevant properties of intravenous lidocaine. Its future perspectives for the prevention of chronicisation of postoperative pain, facilitation of postoperative fast track programs, and prevention of tumoral recurrence are also discussed.

Intensification of GVHD prophylaxis with low-dose ATG-F before allogeneic PBSC transplantation from HLA-identical siblings in adult patients with hematological malignancies: results from a retrospective analysis.

Several studies have shown that chronic GVHD (cGVHD) is more frequent in patients receiving transplants from PBSC than in those receiving BM. In the setting of PBSC-unrelated transplants, the addition of anti-T-cell globulin (ATG) has shown a significant decrease in incidence/severity of cGVHD, without an increase in relapses or infections. However, no prospective data are yet available in the sibling setting. We retrospectively analyzed the effects of intensification of standard GVHD prophylaxis (CsA+MTX) by the addition of low-dose ATG in 245 patients receiving a transplant from HLA-identical sibling. From 1996 to 2001, patients received PBSC as the preferred source (group 2), and then ATG was added before transplant (group 3) because of a high cGVHD rate. Patients receiving BM in the same time period were analyzed as a control group (group 1). The incidence of grade III-IV acute GVHD and cGVHD was not significantly different in the three groups, but extensive cGVHD was highest in group 2 (38%) compared with group 3 (21%) or group 1 (28%; P=0.03). OS, TRM and time to relapse/progression were similar in the three groups. Our analysis shows that adding ATG to PBSC sibling allogeneic transplants can lower cGVHD, without an increase of relapse. Further prospective studies are needed to confirm these findings.

The addition of plerixafor is safe and allows adequate PBSC collection in multiple myeloma and lymphoma patients poor mobilizers after chemotherapy and G-CSF.

We report 13 multiple myeloma (MM) or lymphoma patients who were failing PBSC mobilization after disease-specific chemotherapy and granulocyte-CSF (G-CSF), and received plerixafor to successfully collect PBSCs. Patients were considered poor mobilizers when the concentration of PB CD34(+) cells was always lower than 10 cells/µL, during the recovery phase after chemotherapy and/or were predicted to have inadequate PBSC collection to proceed to autologous transplantation. Plerixafor (0.24 mg/kg) was administered subcutaneously for up to three consecutive days, while continuing G-CSF, 10-11 h before the planned leukapheresis. Plerixafor administration was safe and no significant adverse events were recorded. We observed a 4.7 median fold-increase in the number of circulating CD34(+) cells after plerixafor as compared with baseline CD34(+) cell concentration (from a median of 6.2 (range 1-12) to 21.5 (range 9-88) cells/µL). All patients collected >2 × 10(6) CD34(+) cells/kg in 1-3 leukaphereses. In all, 5/13 patients have already undergone autograft with plerixafor-mobilized PBSCs, showing a rapid and durable hematological recovery. Our results suggest that the pre-emptive addition of plerixafor to G-CSF after chemotherapy is safe and may allow the rescue of lymphoma and MM patients, who need autologous transplantation but are failing PBSC mobilization.

Stem cell mobilization and collection in patients with liver cirrhosis.

BACKGROUND: Bone marrow-derived stem cells (BMSC) and granulocyte colony-stimulating factor (G-CSF) have been proved to contribute to tissue regeneration after liver injury. AIMS: To test the safety of G-CSF and define the exact dose capable of mobilizing BMSC in the majority of patients with liver cirrhosis; and to assess the feasibility of leukapheresis to collect BMSC from peripheral blood. METHODS: In this study, we treated 18 patients affected by liver cirrhosis with increasing doses of G-CSF to mobilize CD34(+) and CD133(+) BMSC into the peripheral blood. RESULTS: The dose-finding phase demonstrated that 15 microg/kg/day of G-CSF is the optimal dose to mobilize both CD34(+) and CD133(+) stem cells. Circulating BMSC were collected by a single step leukapheresis in three patients and the mean number of CD34(+) and CD133(+) cells cryopreserved was 1.3 +/- 0.7 and 1.2 +/- 0.5 x 10(6)/kg, respectively. No severe adverse events were observed during the drug administration and stem cell collection. Noteworthy is, none of the patients showed a significant modification of liver function. CONCLUSIONS: Our study demonstrates that G-CSF administration and BMSC collection from the peripheral blood is possible and safe in patients with liver cirrhosis. The optimal dose to mobilize BMSC in cirrhotics is 15 microg/kg/day. At this dose, G-CSF does not seem to modify the residual liver function in cirrhotic patients.

Short- and long-term haematological surveillance of healthy donors of allogeneic peripheral haematopoietic progenitors mobilized with G-CSF: a single institution prospective study.

Healthy allogeneic donors, who were treated with G-CSF and underwent peripheral blood haematopoietic precursor collection at our Institution, were enrolled in a short- and long-term haematological surveillance protocol for a 5--7--year period. To date, 94 donors have been assessed with a mean follow-up of 30 months (4--84); for 30 subjects, the follow-up is >or=48 months. During G-CSF administration, 23/94 donors showed a significant platelet count decrease from the baseline. Pre-apheresis platelet decrement correlated with the total G-CSF dose administered, baseline platelet level and donor age. Normal platelet counts returned within 4--8 months. PMN and/or lymphocyte lower values were observed in 55/94 donors 2 weeks after G-CSF administration, with mean drops from the baseline of 40 and 36% for PMN and lymphocytes, respectively. The PMN decrease correlated inversely with donor age, as younger donors were more affected than older ones, whereas the lymphocyte decrease correlated directly with the total blood volumes processed in the apheresis courses, in particular for donors subjected to large volume leukaphereses. Long-term observation showed moderate neutrophil reduction (25% count drop from the baseline) in four of the 30 donors observed for four years or more. 14 donors showed persistent, slight lymphocytopenia (mean drop of 13%) until the third year, with recovery in the fourth year of follow-up.

Temporary graft for closed-system cataract surgery during corneal triple procedures.

Performing phacoemulsification during a triple corneal procedure has many advantages. Operating in a closed chamber makes surgery easier and safer. In some cases, however, a dense corneal opacity may prevent closed-chamber surgery, necessitating the use of an open-sky technique. In these cases, a temporary corneal graft using a corneal button not suitable for penetrating keratoplasty is proposed to allow phacoemulsification and foldable intraocular lens implantation through a corneal tunnel. The temporary corneal graft is replaced with a permanent graft after these steps are completed. This technique was effective in 3 patients with cataract and dense corneal opacity.

Tumors of the spine. Indications for surgical treatment.

The authors analyze problems inherent to the treatment of spine tumors (in particular surgical indications) especially with regard to metastases. The purpose of treatment must be that of improving the quality of life and, perhaps, prognosis. In this sense it is hoped that when indications exist surgical treatment will be as timely and radical as possible.

[Surgical therapy of obstructive azoospermia: microsurgery]. / Terapia chirurgica dell'azoospermia ostruttiva: microchirurgia.

Microscopic procedures for therapy of obstructive azoospermia or of vasectomy reversals have resulted in accurate reapproximation of ductal structures. The success of vasovasostomy appears to be influenced by the length of time that has passed since the vasectomy was performed or the obstruction become. Failures of vasovasostomy may be attributed to anastomotic stenosis, sperm antibodies, epididymal dysfunction, or an unrecognized epididymal tubule blowout with subsequent obstruction. The latter condition should by suspected when, at the time of the initial vasovasostomy, there is lack of fluid containing spermatozoa in the cut end of the testicular portion of the vas. Chronic intratubular pressure may cause an epididymal blowout, with subsequent spermatic granuloma and obstruction in the epididymal tubule, that may also be related to a congenital disorder or a postinflammatory condition. Spermatozoa gain maturation and the capacity for motility as they move from the caput to the cauda of the epididymis as possible. Microsurgery allows direct microtubular anastomosis between the epididymal tubule and the cut end of the vas. Some conditions are not amenable to conventional surgical techniques, such obstructed azoospermia due to congenital bilateral absence of the vas deferens or to severe damage to the reproductive ducts. To treat these patients surgeons have devised reservoirs (artificial spermatoceles) to collect spermatozoa to be used for artificial insemination. An alternative treatment method for obstructed azoospermia is to obtain sperm from the epididymis with the use of an operating microscope. Although sperm have been obtained the poor sperm motility requires either in vitro fertilization or GIFT. The technique looks promising, although improved techniques to enhance the motility of the collected sperm will ultimately yield better results.

Concomitant mobilization of plasma cells and hematopoietic progenitors into peripheral blood of multiple myeloma patients: positive selection and transplantation of enriched CD34+ cells to remove circulating tumor cells.

One advantage of the use of peripheral blood stem cells (PBSCs) over autologous bone marrow would be a reduced risk of tumor cell contamination. However, the level of neoplastic cells in the PB of multiple myeloma (MM) patients after mobilization protocols is poorly investigated. In this study, we evaluated PB samples from 27 pretreated MM patients after the administration of high dose cyclophosphamide (7 g/m2 or 4 g/m2) and granulocyte-colony stimulating factor for the detection of myeloma cells as well as hematopoietic progenitors. Plasma cells containing intracytoplasmic lg were counted by microscope immunofluorescence after incubation with appropriate antisera directed against light- and heavy-chain lg. Moreover, flow cytometry studies were performed to determine the presence of malignant B-lineage elements by using monoclonal antibodies against the CD19 antigen and the monotypic light chain. Before initiation of PBSC mobilization, circulating plasma cells were detected in all MM patients in a percentage ranging from 0.1% to 1.8% of the mononuclear cell fraction (mean value, 0.7% +/- 0.4% SD). In these patients, a higher absolute number of PB neoplastic cells was detected after chemotherapy and granulocyte colony-stimulating factor. Kinetic analysis showed a pattern of tumor cell mobilization similar to that of normal hematopoietic progenitors with a maximum peak falling within the optimal time period for the collection of PBSCs. The absolute number of plasma cells showed a 10 to 50-fold increase as compared with the baseline value. Apheresis products contained 0.7% +/- 0.2% SD of myeloma cells (range, 0.2% to 2.7%). Twenty-three MM patients were submitted to PBSC collection. In 10 patients, circulating hematopoietic CD34+ cells were highly enriched by avidin-biotin immunoabsorption, were cryopreserved, and used to reconstitute bone marrow function after myeloablative therapy. The median purity of the enriched CD34+ cell population was 89.5% (range, 51% to 94%), with a 75-fold increase as compared with the pretreatment samples. The median overall recovery of CD34+ cells and colony-forming unit-granulocyte-macrophage was 58% (range, 33% to 95%) and 45% (range, 7% to 100%), respectively. Positive selection of CD34+ cells resulted in 2.5- to 3-log depletion of plasma cells and CD19+ B-lineage cells as determined by immunofluorescence studies, although DNA analysis of CDR III region of IgH gene showed the persistence of minimal residual disease in 5 of 6 patient samples studied. Myeloma patients were reinfused with enriched CD34+ cells after myeloablative therapy consisting of total body irradiation (1,000 cGy) and highdose melphalan (140 mg/m2). They received a median of 4 x 10(6) CD34+ cells/kg and showed a rapid reconstitution of hematopoiesis; the median time to 0.5 x 10(9) neutrophils and to 20 and 50 x 10(9) platelets per liter of PB was 10, 11, and 12 days, respectively. These results, as well as other clinically significant parameters, did not significantly differ from those of patients (n = 13) receiving unmanipulated PBSCs after the same pretransplant conditioning regimen. In summary, our data show the concomitant mobilization of tumor cells and hematopoietic progenitors in the PB of MM patients. Positive selection of CD34+ cells reduces the contamination of myeloma cells from the apheresis products up to 3-log and provides a cell suspension capable of restoring a normal hematopoiesis after a total body irradiation-containing conditioning regimen.