Efficacy and safety of ultrasound-guided core needle biopsies (US-CNBs) in cervical lymphadenopathy in patients with suspected head and neck cancer during the COVID-19 pandemic.

BACKGROUND: Cervical lymphadenopathy can be benign or malignant. Its accurate diagnosis is necessary to determine appropriate treatment. Ultrasound-guided core needle biopsies (US-CNBs) are frequently used as a percutaneous sampling approach. OBJECTIVES: Our aim was to identify the efficacy and safety of US-CNBs in 125 patients with cervical lymphadenopathy and clinically suspected head and neck cancer during the COVID-19 pandemic with limited surgical resources. METHODS: US-CNBs of pathological lymph nodes were performed in 146 lymph nodes on 125 patients. Biopsies were performed ultrasound-guided with a reusable gun core biopsy system and a 10-cm-long 16-G needle. Standard of reference for the histological findings were panendoscopy, clinical and sonographic follow-up, surgical biopsy or a repeat US-CNB. RESULTS: Adequate material for histologic diagnosis was obtained in 111 patients (89%), of these 83 patients (75%) were diagnosed as malignant, whereas benign lymphadenopathy accounted for 28 patients (25%). Therefore, US-CNB was able to identify malignant or benign lymphadenopathy with an overall accuracy of 88% and 90%, respectively. CONCLUSIONS: Percutaneous US-CNB is a safe and effective alternative to surgical biopsy in the management of cervical lymphadenopathy in patients with clinically suspected head and neck cancer in a setting with limited resources.

Diagnostic Value of Diffusion-Weighted Imaging with Background Body Signal Suppression (DWIBS) for the Pre-Therapeutic Loco-Regional Staging of Cervical Cancer: A Feasibility and Interobserver Reliability Study.

(1) Background: cervical cancer is one of the leading causes of cancer-related deaths and the fourth most common cancer among women worldwide. Magnetic resonance imaging (MRI) is the modality of choice for loco-regional staging of cervical cancer in the primary diagnostic workup beginning with at least stage IB. (2) Methods: we retrospectively analyzed 16 patients with histopathological proven cervical cancer (FIGO IB1−IVA) for the diagnostic accuracy of standard MRI and standard MRI with diffusion-weighted imaging with background body signal suppression (DWIBS) for the correct pre-therapeutic assessment of the definite FIGO category. (3) Results: In 7 out of 32 readings (22%), DWIBS improved diagnostic accuracy. With DWIBS, four (13%) additional readings were assigned the correct major (I−IV) FIGO stages pre-therapeutically. Interobserver reliability of DWIBS was weakest for parametrial infiltration (k = 0.43; CI-95% 0.00−1.00) and perfect for tumor size <2 cm, infiltration of the vaginal lower third, infiltration of adjacent organs and loco-regional nodal metastases (k = 1.000; CI-95% 1.00−1.00). (4) Conclusions: the pre-therapeutic staging of cervical cancer has a high diagnostic accuracy and interobserver reliability when using standard MRI but can be further optimized with the addition of DWIBS sequences when reporting is performed by an experienced radiologist.

Stanniocalcin 1 is overexpressed in multipotent mesenchymal stromal cells from acute myeloid leukemia patients.

Objectives: Multipotent mesenchymal stromal cells (MSC) play a pivotal role in the bone marrow (BM) niche. Stanniocalcin 1 (STC1) secreted by MSC has been demonstrated to promote the survival of neoplastic cells and was suggested a marker for minimal residual disease of acute myeloid leukemia (AML). Therefore, we evaluated the expression of STC1 in MSC from AML patients (MSCAML) compared to MSC from healthy donors (MSCHD).Methods: Liquid culture assays of MSCAML and MSCHD were performed to compare expansion capacity. Gene expression profiles of MSCAML vs. MSCHD were established. Secretion of STC1 was tested by ELISA in MSCAML vs. MSCHD and expression of STC1 in AML- vs. HD-BM by immunohistochemistry. In addition, co-cultures of AML cells on MSC were initiated and ultrastructural intercellular communication patterns were investigated. Finally, the effect of blocking STC1 on AML cells was evaluated.Results: MSCAML showed significant decreased expansion capacity compared to MSCHD. Gene analysis revealed marked overexpression of STC1 in MSCAML. ELISA and immunohistochemical findings confirmed this observation. Electron microscopy analysis showed reciprocal stimulation between AML cells and MSC. Blockade of STC1 did not significantly affect AML cell proliferation and apoptosis.Discussion: Characteristics of MSC differ depending on whether they originate from AML patients or from HD. STC1 was mostly overexpressed in MSCAML compared to MSCHD. In vitro blockade of STC1, however, was not associated with AML cell proliferation and apoptosis.Conclusion: Differences in expression levels of glycoproteins from MSCAML compared to MSCHD not necessarily assume that these molecules are niche-relevant in leukemic disease.

Modeling and Bioinformatics Identify Responders to G-CSF in Patients With Amyotrophic Lateral Sclerosis.

Objective: Developing an integrative approach to early treatment response classification using survival modeling and bioinformatics with various biomarkers for early assessment of filgrastim (granulocyte colony stimulating factor) treatment effects in amyotrophic lateral sclerosis (ALS) patients. Filgrastim, a hematopoietic growth factor with excellent safety, routinely applied in oncology and stem cell mobilization, had shown preliminary efficacy in ALS. Methods: We conducted individualized long-term filgrastim treatment in 36 ALS patients. The PRO-ACT database, with outcome data from 23 international clinical ALS trials, served as historical control and mathematical reference for survival modeling. Imaging data as well as cytokine and cellular data from stem cell analysis were processed as biomarkers in a non-linear principal component analysis (NLPCA) to identify individual response. Results: Cox proportional hazard and matched-pair analyses revealed a significant survival benefit for filgrastim-treated patients over PRO-ACT comparators. We generated a model for survival estimation based on patients in the PRO-ACT database and then applied the model to filgrastim-treated patients. Model-identified filgrastim responders displayed less functional decline and impressively longer survival than non-responders. Multimodal biomarkers were then analyzed by PCA in the context of model-defined treatment response, allowing identification of subsequent treatment response as early as within 3 months of therapy. Strong treatment response with a median survival of 3.8 years after start of therapy was associated with younger age, increased hematopoietic stem cell mobilization, less aggressive inflammatory cytokine plasma profiles, and preserved pattern of fractional anisotropy as determined by magnetic resonance diffusion tensor imaging (DTI-MRI). Conclusion: Long-term filgrastim is safe, is well-tolerated, and has significant positive effects on disease progression and survival in a small cohort of ALS patients. Developing and applying a model-based biomarker response classification allows use of multimodal biomarker patterns in full potential. This can identify strong individual treatment responders (here: filgrastim) at a very early stage of therapy and may pave the way to an effective individualized treatment option.

Effects of continuous high-dose G-CSF administration on hematopoietic stem cell mobilization and telomere length in patients with amyotrophic lateral sclerosis - a pilot study.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of complex and still poorly understood etiology. Loss of upper and lower motoneurons results in death within few years after diagnosis. Recent studies have proposed neuroprotective and disease-slowing effects of granulocyte-colony stimulating factor (G-CSF) treatment in ALS mouse models as well as humans. In this study, six ALS patients were monitored up to 3.5 years during continuous high-dose G-CSF administration. Repetitive analyses were performed including blood count parameters, CD34+ hematopoietic stem and progenitor cell (HSPC) and colony forming cell (CFC) counts, serum cytokine levels and leukocyte telomere length. We demonstrate that continuous G-CSF therapy was well tolerated and safe resulting in only mild adverse events during the observation period. However, no mobilization of CD34+ HSPC was detected as compared to baseline values. CFC mobilization was equally low and even a decrease of myeloid precursors was observed in some patients. Assessment of telomere length within ALS patients' leukocytes revealed that G-CSF did not significantly shorten telomeres, while those of ALS patients were shorter compared to age-matched healthy controls, irrespective of G-CSF treatment. During G-CSF stimulation, TNF-alpha, CRP, IL-16, sVCAM-1, sICAM-1, Tie-2 and VEGF were significantly increased in serum whereas MCP-1 levels decreased. In conclusion, our data show that continuous G-CSF treatment fails to increase circulating CD34+ HSPC in ALS patients. Cytokine profiles revealed G-CSF-mediated immunomodulatory and proteolytic effects. Interestingly, despite intense G-CSF stimulation, telomere length was not significantly shortened.

A new exon 12 mutation in the EPAS1 gene possibly associated with erythrocytosis.

In secondary erythrocytosis, the elevated red cell count is powered by factors outside the erythroid compartment, for instance by raised erythropoietin (EPO) synthesis based on congenital defects of the oxygen-sensing pathway. The principal transcriptional regulator of EPO synthesis is endothelial PAS domain-containing protein 1 (EPAS 1). We present here the first report of a patient with erythrocytosis involving a mutation of amino acid 525 in EPAS1. The p.Asp525His mutation affects a residue that is farthermost from primary functional site Pro-531 of any of the erythrocytosis-related mutations that have been identified up to now.

Biomarker Supervised G-CSF (Filgrastim) Response in ALS Patients.

Objective: To evaluate safety, tolerability and feasibility of long-term treatment with Granulocyte-colony stimulating factor (G-CSF), a well-known hematopoietic stem cell factor, guided by assessment of mobilized bone marrow derived stem cells and cytokines in the serum of patients with amyotrophic lateral sclerosis (ALS) treated on a named patient basis. Methods: 36 ALS patients were treated with subcutaneous injections of G-CSF on a named patient basis and in an outpatient setting. Drug was dosed by individual application schemes (mean 464 Mio IU/month, range 90-2160 Mio IU/month) over a median of 13.7 months (range from 2.7 to 73.8 months). Safety, tolerability, survival and change in ALSFRS-R were observed. Hematopoietic stem cells were monitored by flow cytometry analysis of circulating CD34+ and CD34+CD38- cells, and peripheral cytokines were assessed by electrochemoluminescence throughout the intervention period. Analysis of immunological and hematological markers was conducted. Results: Long term and individually adapted treatment with G-CSF was well tolerated and safe. G-CSF led to a significant mobilization of hematopoietic stem cells into the peripheral blood. Higher mobilization capacity was associated with prolonged survival. Initial levels of serum cytokines, such as MDC, TNF-beta, IL-7, IL-16, and Tie-2 were significantly associated with survival. Continued application of G-CSF led to persistent alterations in serum cytokines and ongoing measurements revealed the multifaceted effects of G-CSF. Conclusions: G-CSF treatment is feasible and safe for ALS patients. It may exert its beneficial effects through neuroprotective and -regenerative activities, mobilization of hematopoietic stem cells and regulation of pro- and anti-inflammatory cytokines as well as angiogenic factors. These cytokines may serve as prognostic markers when measured at the time of diagnosis. Hematopoietic stem cell numbers and cytokine levels are altered by ongoing G-CSF application and may potentially serve as treatment biomarkers for early monitoring of G-CSF treatment efficacy in ALS in future clinical trials.

TGF-ß1 and CXCL12 modulate proliferation and chemotherapy sensitivity of acute myeloid leukemia cells co-cultured with multipotent mesenchymal stromal cells.

OBJECTIVES: Multipotent mesenchymal stromal cells (MSCs) play a central role within the bone marrow (BM) niche, supporting hematopoiesis via soluble factors like cytokines and chemokines. In our study, we sought to investigate the effect of blocking transforming growth factor beta 1 (TGF-ß1) and C-X-C motif chemokine 12 (CXCL12) receptor CXCR4 on acute myeloid leukemia (AML) cells in an MSC co-culture system. METHODS: Human MSCs were obtained by BM aspirates and their phenotype and functional properties were confirmed in vitro. Co-cultures of AML cells on MSCs were initiated and compared to those on mouse fibroblasts (MS-5) and liquid cultures. Additionally, the effect of blocking CXCR4 and TGF-ß1 on AML cells was tested with and without the addition of cytarabine. RESULTS: MSCs from BM showed a typical phenotype and differentiation pattern. Co-culture of AML cells on MSCs resulted in a significantly higher proliferation capacity than on MS-5 or liquid culture. Blockade of TGF-ß1 increased AML cell proliferation and chemosensibility, while the CXCR4 antagonist plerixafor showed anti-proliferative effects and did not change cytarabine-induced cell death compared to control. DISCUSSION: Human MSCs are potent feeder cells, able to maintain AML cells in long-term culture. This favorable co-existence seems to be due in part to molecules important for communication within the niche. Blockade of TGF-ß1 and CXCL12 was associated with different effects on AML cell proliferation and chemotherapy resistance. CONCLUSION: These findings suggest a strong supporting affinity between MSCs and AML cells within the leukemic niche, where TGF-ß1 and CXCL12 pathways play an important role.

Splenic pooling and loss of VCAM-1 causes an engraftment defect in patients with myelofibrosis after allogeneic hematopoietic stem cell transplantation.

Myelofibrosis is a myeloproliferative neoplasm that results in cytopenia, bone marrow fibrosis and extramedullary hematopoiesis. Allogeneic hematopoietic stem cell transplantation is the only curative treatment but is associated with a risk of delayed engraftment and graft failure. In this study, patients with myelofibrosis (n=31) and acute myeloid leukemia (n=31) were analyzed for time to engraftment, graft failure and engraftment-related factors. Early and late neutrophil engraftment and late thrombocyte engraftment were significantly delayed in patients with myelofibrosis as compared to acute myeloid leukemia, and graft failure only occurred in myelofibrosis (6%). Only spleen size had a significant influence on engraftment efficiency in myelofibrosis patients. To analyze the cause for the engraftment defect, clearance of hematopoietic stem cells from peripheral blood was measured and immunohistological staining of bone marrow sections was performed. Numbers of circulating CD34+ were significantly reduced at early time points in myelofibrosis patients, whereas CD34+CD38- and colony-forming cells showed no significant difference in clearance. Staining of bone marrow sections for homing proteins revealed a loss of VCAM-1 in myelofibrosis with a corresponding significant increase in the level of soluble VCAM-1 within the peripheral blood. In conclusion, our data suggest that reduced engraftment and graft failure in myelofibrosis patients is caused by an early pooling of CD34+ hematopoietic stem cells in the spleen and a bone marrow homing defect caused by the loss of VCAM-1. Improved engraftment in myelofibrosis might be achieved by approaches that reduce spleen size and cleavage of VCAM-1 in these patients prior to hematopoietic stem cell transplantation.

Therapeutic targeting and rapid mobilization of endosteal HSC using a small molecule integrin antagonist.

The inherent disadvantages of using granulocyte colony-stimulating factor (G-CSF) for hematopoietic stem cell (HSC) mobilization have driven efforts to identify alternate strategies based on single doses of small molecules. Here, we show targeting α9ß1/α4ß1 integrins with a single dose of a small molecule antagonist (BOP (N-(benzenesulfonyl)-L-prolyl-L-O-(1-pyrrolidinylcarbonyl)tyrosine)) rapidly mobilizes long-term multi-lineage reconstituting HSC. Synergistic engraftment augmentation is observed when BOP is co-administered with AMD3100. Impressively, HSC in equal volumes of peripheral blood (PB) mobilized with this combination effectively out-competes PB mobilized with G-CSF. The enhanced mobilization observed using BOP and AMD3100 is recapitulated in a humanized NODSCIDIL2Rγ(-/-) model, demonstrated by a significant increase in PB CD34(+) cells. Using a related fluorescent analogue of BOP (R-BC154), we show that this class of antagonists preferentially bind human and mouse HSC and progenitors via endogenously primed/activated α9ß1/α4ß1 within the endosteal niche. These results support using dual α9ß1/α4ß1 inhibitors as effective, rapid and transient mobilization agents with promising clinical applications.

Retinal Involvement in a Patient with Cerebral Manifestation of Chronic Graft-Versus-Host-Disease.

BACKGROUND: We report a 35-year-old female patient with cerebral manifestations of chronic graft-versus-host disease (cGvHD) and putative retinal involvement after allogeneic peripheral blood stem cell transplantation (alloHSCT). PATIENT AND METHODS: The patient experienced recurrent episodes of fever and encephalitic signs 7 months after alloHSCT during taper of immunosuppression (IS). RESULTS: Cerebral magnetic resonance imaging (MRI) showed non-gadolinium-enhancing confluent periventricular lesions and cerebrospinal fluid inflammation. After exclusion of infectious causes, treatment with steroids and antiepileptics improved cognitive deficits. Steroid reduction provoked a relapse responding to IS. 2 years later, she complained of right-sided blurred vision and floaters; both eyes showed whitish circumscribed retinal infiltrations, cellular infiltration of the vitreous and mild bilateral optic disc edema. Oncological and neurological work-up ruled out infectious diseases and other GvHD manifestations. Symptoms and signs resolved under continued systemic IS, leaving pigmented retinal scars. After IS withdrawal, classical cutaneous cGvHD developed, resolving on systemic IS. 94 months after transplantation, she is doing well. CONCLUSION: To our knowledge, this is the first observation of retinal involvement of cerebral cGvHD manifestations with retinal infiltrations documented in the absence of other causes and in parallel to periventricular lesions in cerebral MRI. Based on bone marrow histology, we discuss a small vessel pathophysiology of cGvHD.

Safety and feasibility of long term administration of recombinant human granulocyte-colony stimulating factor in patients with amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neuronal disease resulting in a loss of the upper and lower motor neurons and subsequent death within three to four years after diagnosis. Mouse models and preliminary human exposure data suggest that the treatment with granulocyte-colony stimulating factor (G-CSF) has neuro-protective effects and may delay ALS progression. As data on long-term administration of G-CSF in patients with normal bone marrow (BM) function are scarce, we initiated a compassionate use program including 6 ALS patients with monthly G-CSF treatment cycles. Here we demonstrate that G-CSF injection was safe and feasible throughout our observation period up to three years. Significant decrease of mobilization efficiency occurred in one patient and a loss of immature erythroid progenitors was observed in all six patients. These data imply that follow-up studies analyzing BM function during long-term G-CSF stimulation are required.

The role of Tenascin C in the lymphoid progenitor cell niche.

Hemopoietic stem cells (HSCs) are extrinsically controlled by the bone marrow (BM) microenvironment. Mice devoid of the extracellular matrix molecule Tenascin-C (TNC) were reported to develop normally. The current study explores the relationship between TNC and hemopoiesis, from HSCs within their niche to maturing progenitors in alternate niches. Although the absence of TNC did not alter the size of the BM stem cell pool, we report decreased thymic T cell progenitors with redistribution to other lymphoid organs, suggesting an anchoring role for TNC. TNC did not play an essential role in stem and progenitor cell homing to BM, but significantly altered lymphoid primed progenitor cell homing. These cells express the TNC receptor, integrin α9ß1, with the same reduced homing evident in the absence of this integrin. The absence of TNC also resulted in an increased proportion and number of mature circulating T cells. In addition, the absence of TNC significantly impaired hemopoietic reconstitution after transplant and increased stem and progenitor cell mobilization. In summary, our analysis revealed unidentified roles for TNC in hemopoiesis: in lineage commitment of thymic T cell progenitors, peripheral T cell migration, and hemopoietic reconstitution.

Granulocyte colony stimulating factor expands hematopoietic stem cells within the central but not endosteal bone marrow region.

Granulocyte colony stimulating factor (G-CSF) is clinically well established for the mobilization of hematopoietic stem cells (HSC). Extensive data on the underlying mechanism of G-CSF induced mobilization is available; however, little is known regarding the functional effect of G-CSF on HSC within the bone marrow (BM). In this study we analyzed the proportion and number of murine HSC in the endosteal and central bone marrow regions after 4 days of G-CSF administration. We demonstrate that the number of HSC, defined as CD150(+)CD48(-)LSK cells (LSKSLAM cells), increased within the central BM region in response to G-CSF, but not within the endosteal BM region. In addition the level of CD150 and CD48 expression also increased on cells isolated from both regions. We further showed that G-CSF mobilized proportionally fewer LSKSLAM compared to LSK cells, mobilized LSKSLAM had colony forming potential and the presence of these cells can be used as a measure for mobilization efficiency. Together we provide evidence that HSC in the BM respond differently to G-CSF and this is dependent on their location. These findings will be valuable in developing new agents which specifically mobilize HSC from the endosteal BM region, which we have previously demonstrated to have significantly greater hematopoietic potential compared to their phenotypically identical counterparts located in other regions of the BM.

The relationship between bone, hemopoietic stem cells, and vasculature.

A large body of evidence suggests hemopoietic stem cells (HSCs) exist in an endosteal niche close to bone, whereas others suggest that the HSC niche is intimately associated with vasculature. In this study, we show that transplanted hemopoietic stem and progenitor cells (HSPCs) home preferentially to the trabecular-rich metaphysis of the femurs in nonablated mice at all time points from 15 minutes to 15 hours after transplantation. Within this region, they exist in an endosteal niche in close association with blood vessels. The preferential homing of HSPCs to the metaphysis occurs rapidly after transplantation, suggesting that blood vessels within this region may express a unique repertoire of endothelial adhesive molecules. One candidate is hyaluronan (HA), which is highly expressed on the blood vessel endothelium in the metaphysis. Analysis of the early stages of homing and the spatial dis-tribution of transplanted HSPCs at the single-cell level in mice devoid of Has3-synthesized HA, provides evidence for a previously undescribed role for HA expressed on endothelial cells in directing the homing of HSPCs to the metaphysis.

Methods to analyze the homing efficiency and spatial distribution of hematopoietic stem and progenitor cells and their relationship to the bone marrow endosteum and vascular endothelium.

The tracking of immunofluorescent labeled hematopoietic stem and progenitor cells (HSC/HPC) within the bone marrow (BM) cavity allows the assessment of the regulatory processes involved in transendothelial migration, trans-marrow migration, and finally lodgement into the HSC niche. This is of interest as the extracellular and cellular components involved in the regulation of HSC quiescence and differentiation are still not completely understood. Homing of transplanted HSC is the first critical step in the interaction between HSC and the microenvironment of the BM. As a consequence, murine models allowing the evaluation of the structural relationship between migrating HSC, the endosteal bone surface, and the vascular components of the BM enhance our understanding of hematopoietic regulation.

Phenotypically identical hemopoietic stem cells isolated from different regions of bone marrow have different biologic potential.

Hemopoietic stem cells (HSCs) reside within a specified area of the bone marrow (BM) cavity called a "niche" that modulates HSC quiescence, proliferation, differentiation, and migration. Our previous studies have identified the endosteal BM region as the site for the HSC niche and demonstrated that hemopoietic stem and progenitor populations (HSPCs, LSK) isolated from different BM regions exhibit significantly different hemopoietic potential. In this study, we have analyzed subpopulations of LSK cells isolated from different regions of the BM and showed that CD150(+)CD48(-)LSK HSCs within the endosteal BM region have superior proliferative capacity and homing efficiency compared with CD150(+)CD48(-)LSK HSCs isolated from the central BM. Furthermore, we show, for the first time, that a subset of CD150(+)CD48(+)LSK progenitor cells, previously defined as B-lymphoid primed hemopoietic cells, are capable of multilineage reconstitution, however, only when isolated from the endosteal region. In addition, we provide evidence for an unrecognized role of CD48 in HSC homing. Together, our data provide strong evidence that highly purified HSCs show functional differences depending on their origin within the BM and that the most primitive HSCs reside within the endosteal BM region.

Thrombin-cleaved osteopontin regulates hemopoietic stem and progenitor cell functions through interactions with alpha9beta1 and alpha4beta1 integrins.

Osteopontin (OPN), a multifunctional acidic glycoprotein, expressed by osteoblasts within the endosteal region of the bone marrow (BM) suppresses the proliferation of hemopoietic stem and progenitor cells and also regulates their lodgment within the BM after transplantation. Herein we demonstrate that OPN cleavage fragments are the most abundant forms of this protein within the BM. Studies aimed to determine how hemopoietic stem cells (HSCs) interact with OPN revealed for the first time that murine and human HSCs express alpha(9)beta(1) integrin. The N-terminal thrombin cleavage fragment of OPN through its binding to the alpha(9)beta(1) and alpha(4)beta(1) integrins plays a key role in the attraction, retention, regulation, and release of hemopoietic stem and progenitor cells to, in, and from their BM niche. Thrombin-cleaved OPN (trOPN) acts as a chemoattractant for stem and progenitor cells, mediating their migration in a manner that involves interaction with alpha(9)beta(1) and alpha(4)beta(1) integrins. In addition, in the absence of OPN, there is an increased number of white blood cells and, specifically, stem and progenitor cells in the peripheral circulation.

Detection and quantification of functionally defined hematopoietic progenitor cells and tissue specific mRNA within the peripheral blood of myeloma patients after administration of granulocyte colony-stimulating factor and erythropoietin.

OBJECTIVE: Hematopoietic progenitor cells (HPC) as well as tissue committed stem cells expressing mRNA specific to various somatic tissues are thought to be part of the CD34+ bone marrow compartment. In this study, we explore and quantify their mobilization in patients with multiple myeloma undergoing chemotherapy upon administration of granulocyte colony-stimulating factor (G-CSF) plus/minus erythropoietin (EPO). PATIENTS AND METHODS: HPC were quantified by flow cytometry and functional assays within the blood of healthy donors and myeloma patients before and after chemotherapy followed by G-CSF or G-CSF + EPO given subcutaneously. The mRNA expression was studied by quantitative polymerase chain reaction (PCR). Cytokines and peripheral blood protease levels were measured by an enzyme-linked immunosorbent assay. RESULTS: EPO did not significantly alter the number of HPC mobilized by G-CSF alone, and mRNA specific for liver, brain, muscle and kidney was detected in both treatment groups. Quantitative PCR analysis revealed a 2.7-fold increased expression of glial fibrillary acidic protein after G-CSF + EPO administration compared to G-CSF alone (P = 0.003). The concentration of G-CSF rose from 62 +/- 22 pg/mL and 48 +/- 10 pg/mL to 28 +/- 9 ng/mL and 85 +/- 10 ng/mL after 10 d of treatment with G-CSF and G-CSF + EPO, respectively. The concentration of neutrophil elastase (NE) rose only in the G-CSF group by a factor 1.5. CONCLUSION: The alteration of G-CSF and NE levels as well as the expression of tissue committed RNA after the administration of EPO in addition to G-CSF indicate that different growth factors mobilize different stem cells that might potentially be used for the support of tissue repair in future treatment protocols.