Regeneration of Gastrocnemius Muscle and State of Immune System in γ-Irradiated Rats under the Influence of He-Ne Laser

We studied the influence of a low-energy He-Ne laser on the regeneration of the transected gastrocnemius muscle and state of the thymus and bone marrow in adult mongrel rats irradiated at 6 Gy using the histological, morphometric, and cytogenetic methods. The laser influence on both rat hind limbs (at total doses of 9.0–10.8 J/cm²) enhanced the regenerative capacity of the viradiated traumatized skeletal muscle, and reduced cytogenetic damage in the bone marrow and thymus cells. The changes in the thymus mass and histostructure suggest that the functional load on the thymus increased under studied the experimental conditions.     

Imatinib treatment induces CD5+ B lymphocytes and IgM natural antibodies with anti-leukemic reactivity in patients with chronic myelogenous leukemia

Imatinib mesylate is a first line treatment of Chronic Myelogenous Leukemia and of a rare form of gastrointestinal stromal cancer, where the response to the drug is also linked to the immune system activation with production of antineoplastic cytokines. In this study, forty patients in the chronic phase of disease, treated with imatinib mesylate, were analyzed. Bone marrow aspirates were drawn at diagnosis, after 3, 6, 12, 18 months for haematological, cytofluorimetric, cytogenetic, biomolecular evaluation and cytokine measurement. Responder and non responder patients were defined according to the European LeukemiaNet recommendations. In responder patients (n = 32), the percentage of bone marrow CD20⁺CD5⁺sIgM⁺ lymphocytes, and the plasma levels of IgM, were significantly higher, at 3 months and up to 9 months, than in non responders. These IgM reacted with O-linked sugars expressed by leukemic cells and could induce tumor cell apoptosis. In responeìder patients the stromal-derived factor-1 and the B-lymphocyte-activating factor of the tumor necrosis factor family significantly raised in the bone marrow after imatinib administration, together with the bone morphogenetic proteins-2 and −7. All patients with high number of CD20⁺CD5⁺sIgM⁺ cells and high stromal-derived factor-1 and B lymphocyte activating factor levels, underwent complete cytogenetic and/or molecular remission by 12 months. We propose that CD20⁺CD5⁺sIgM⁺ lymphocytes producing anti-carbohydrate antibodies with anti-tumor activity, might contribute to the response to imatinib treatment. As in multivariate analysis bone marrow CD20⁺CD5⁺sIgM⁺ cells and stromal-derived factor-1 and B-lymphocyte-activating factor levels were significantly related to cytogenetical and molecular changes, they might contribute to the definition of the pharmacological response.     

mFISH analysis of chromosomal damage in bone marrow cells collected from CBA/CaJ mice following whole body exposure to heavy ions (<Superscript>56</Superscript>Fe ions)

To date, there is scant information on in vivo induction of chromosomal damage by heavy ions found in space (i.e. ⁵⁶Fe ions). For radiation-induced response to be useful for risk assessment, it must be established in in vivo systems especially in cells that are known to be at risk for health problems associated with radiation exposure (such as hematopoietic cells, the known target tissue for radiation-induced leukemia). In this study, the whole genome multicolor fluorescence in situ hybridization (mFISH) technique was used to examine the in vivo induction of chromosomal damage in hematopoietic tissues, i.e. bone marrow cells. These cells were collected from CBA/CaJ mice at day 7 following whole-body exposure to different doses of 1 GeV/amu ⁵⁶Fe ions (0, 0.1, 0.5 and 1.0 Gy) or ¹³⁷Cs γ rays as the reference radiation (0, 0.5, 1.0 and 3.0 Gy, at the dose rate of 0.72 Gy/min using a GammaCell40). These radiation doses were the average total-body doses. For each radiation type, there were four mice per dose. Several types of aberrations in bone marrow cells collected from mice exposed to either type of radiation were found. These were exchanges and breaks (both chromatid- and chromosome-types). Chromosomal exchanges included translocations (Robertsonian or centric fusion, reciprocal and incomplete types), and dicentrics. No evidence of a non-random involvement of specific chromosomes in any type of aberrations observed in mice exposed to ⁵⁶Fe ions or ¹³⁷Cs γ rays was found. At the radiation dose range used in our in vivo study, the majority of exchanges were simple. Complex exchanges were detected in bone marrow cells collected from mice exposed to 1 Gy of ⁵⁶Fe ions or 3 Gy of ¹³⁷Cs γ rays only, but their frequencies were low. Overall, our in vivo data indicate that the frequency of complex chromosome exchanges was not significantly different between bone marrow cells collected from mice exposed to ⁵⁶Fe ions or ¹³⁷Cs γ rays. Each type of radiation induced significant dose-dependent increases (ANOVA, P < 0.01) in the frequencies of chromosomal damage, including the numbers of abnormal cells. Based upon the linear-terms of dose-response curves, ⁵⁶Fe ions were 1.6 (all types of exchanges), 4.3 (abnormal cells) and 4.2 (breaks, both chromatid- and chromosome-types) times more effective than ¹³⁷Cs γ rays in inducing chromosomal damage.     

Human bone marrow colony growth in agar-gel

A technique for growing human bone marrow cell colonies in agar-gel medium is described. “Feeder layers” containing 1 × 10⁶ normal human peripheral white blood cells are used as the stimulus for colony growth. Human bone marrow aspirates are collected in heparinized syringes and plated as 2 × 10⁵ cells on “feeder layers.” Normal human bone marrow yields 32–102 colonies per 2 × 10⁵ cells plated. Colonies are almost exclusively granulocytic. Growth rate of colonies is slower than with mouse bone marrow but colonies reach a comparable size (500–1500 cells) at days 12–16.     

Cytokines Inducing Bone Marrow SCA+ Cells Migration into Pancreatic Islet and Conversion into Insulin-Positive Cells In Vivo

We hypothesize that specific bone marrow lineages and cytokine treatment may facilitate bone marrow migration into islets, leading to a conversion into insulin producing cells in vivo. In this study we focused on identifying which bone marrow subpopulations and cytokine treatments play a role in bone marrow supporting islet function in vivo by evaluating whether bone marrow is capable of migrating into islets as well as converting into insulin positive cells. We approached this aim by utilizing several bone marrow lineages and cytokine-treated bone marrow from green fluorescent protein (GFP) positive bone marrow donors. Sorted lineages of Mac-1⁺, Mac-1⁻, Sca⁺, Sca⁻, Sca⁻/Mac-1⁺ and Sca⁺/Mac-1⁻ from GFP positive mice were transplanted to irradiated C57BL6 GFP negative mice. Bone marrow from transgenic human ubiquitin C promoter GFP (uGFP, with strong signal) C57BL6 mice was transplanted into GFP negative C57BL6 recipients. After eight weeks, migration of GFP positive donor'' bone marrow to the recipient''s pancreatic islets was evaluated as the percentage of positive GFP islets/total islets. The results show that the most effective migration comes from the Sca⁺/Mac⁻ lineage and these cells, treated with cytokines for 48 hours, were found to have converted into insulin positive cells in pancreatic islets in vivo. This study suggests that bone marrow lineage positive cells and cytokine treatments are critical factors in determining whether bone marrow is able to migrate and form insulin producing cells in vivo. The mechanisms causing this facilitation as well as bone marrow converting to pancreatic beta cells still need to be investigated.     

DNA repair synthesis and chromosomal aberrations induced in vivo by triethylenemelamine

The alkylating agent, triethylenemelamine (TEM), was studied for its ability to induce unscheduled DNA (repair) synthesis (UDS) in vivo in rat lymphocytes. Somatic cytogenetic alterations were analyzed (in bone marrow) and compared with UDS as a function of TEM dosage. UDS was evaluated through the use of autoradiography; cytogenetic alterations were studied in metaphase bone marrow chromosome preparations.Data indicated that the degree of UDS is a direct function of TEM dosage up to a rate-limiting concentration, at which point it ceases to be dose dependent. Except for a deviation at the highest dose level tested, the extent of cytogenetic damage was directly and linearly related to TEM dose. Between the control and intermediate (0.2 mg/kg) dose levels, UDS response increased II-fold while cytogenetic damage showed only a 4-fold increase; this disparity diminished with increasing TEM dose. In the lower dose levels, therefore, the greater relative sensitivity of UDS evaluation in the detection of genetic activity may be indicated. Patterns of UDS response observed through the in vivo assay developed in this study were found to be analogous to those established in in vitro studies.     

Evaluation of chemically induced cytogenetic lesions in rabbit oocytes: II. A comparison of streptonigrin effects on somatic and germ cells

The dose-response relationships for streptonigrin (NSC-45383)-induced chromosome aberrations in rabbit somatic cells are compared with dose-response data derived from the analysis of inherited structural chromosome abnormalities in preimplantation embryos from female rabbits treated with streptonigrin prior to mating. The incidence of inherited aberrations assessed in over 1000 karyotype preparations from 361 6-day blastocysts obtained from 55 female rabbits is used to derive a measure of the transmissible cytogenetic damage induced in the oocytes. The cytogenetic damage assessed in 2300 lymphoblast metaphases from 23 rabbits and 2750 marrow-derived metaphases from 27 rabbits which were collected and prepared for examination 6 h after the initiation of streptonigrin dosing are used to obtain estimates of the somatic cell insult. A uniform maximum likelihood analysis technique is applied individually to the 3 sets of data to derive the coefficients of the dose-response relationships. The resulting equations are Y = 0.6 ± 28.0 (×10^?5) + 8.2 ± 5.1 (×10^?4χ for inherited aberrations in 6-day blastocysts, Y = 9.7 ± 3.3 (×10^?3 + 1.9 ± (×10^?3)χ for bone-marrow cells, and Y = 2.8 ± 0.7 (×10^?2 + 4.8 ± 0.2 (×10^?3)χ for the lymphoblasts. In the somatic tissues Y is the percentage of cells with chromosome breakage, while in the blastocyst data Y is the percentage of 6-day blastocysts with consistent structural chromosome aberrations, and in all equations χ is the total streptonigrin dose in μg/kg.The study shows that streptonigrin injections in the range of 30–90 μg/kg when given to sexually mature female rabbits cause dose-dependent increases in chromosome aberrations in 2 types of somatic cells and in the incidence of inherited aberrations recovered in 6-day blastocysts. The coefficients of damage recovered in blastocysts versus damage recovered in somatic cells have the ratio of 1:2.3:5.8 (blastocysts: bone marrow: lymphoblasts). The results are discussed in terms of risk assessment and kinetics of aberration loss during meiosis and early embryonic development. The conclusion drawn from the study is that somatic cell cytogenetic damage is in some way predictive of damage incurred by oocytes which can be passed on to preimplantation embryos, at least for agents like streptonigrin.     

Vanadate,an inhibitor of tyrosine phosphatases,induced premature anaphase in oocytes and aneuploidy and polyploidy in mouse bone marrow cells

Protein tyrosine phosphatases are needed for activating maturation promoting factor, meiotic spindle assembly and spindle checkpoint inactivation. The protein phosphatase inhibitor vanadate was used to upset the kinase-phosphatase equilibrium during oocyte maturation (OM) and the metaphase anaphase transition (MAT) prior to cytogenetic analyses of mouse oocytes and bone marrow cells. ICR females received pregnant mare serum gonadotrophin (PMSG) and 48h later received human chorionic gonadotrophin (hCG). Vanadate doses of 0, 5, 15, and 25mg/kg were administered intraperitoneally immediately after hCG and ovulated oocytes and bone marrow cells were processed for cytogenetic analyses 18h after hCG. Data were analyzed by Chi-square and Fisher's exact tests. Vanadate induced different cytogenetic abnormalities in oocytes and in bone marrow cells. The frequencies of oocytes exhibiting premature anaphase (spontaneous activation) in vanadate exposed mice were significantly (P<0.01) elevated over controls; whereas, in bone marrow cells, the levels of tetraploidy, hyperploidy and premature centromere separation were significantly (P<0.01) increased by vanadate treatment. These results suggest that alteration of the kinase-phosphatase equilibrium during OM and the MAT leads to cytogenetic abnormalities that differ between oocytes and bone marrow cells.     

Sensitivity of bone marrow cells damaged by antitumor drugs to cytotoxic action of effectors of a normal spleen

Different cytogenetic effects in bone marrow cells induced by antitumor drugs with different mechanisms of action was studied. The treatment of adriablastine causes the appearance of chromatid deletion, vinblastine-polyploid cells, cyclophosphamide-chromosomal and chromatid aberration in mice. It was shown that bone marrow cells with cytogenetic damage have altered susceptibility to normal spleen cells-effectors cytotoxic action.     

Formation of Cyclohexylamine and Cyclohexanone from Cyclamate by Microorganisms Isolated from the Feces of Guinea Pig

The assimilation of sodium cyclamate (CHS-Na) by microorganisms was studied. Fifteen strains of cyclamate-assimilating bacteria were isolated from the feces of guinea pig excreting cyclohexylamine (CHA) in urine. The majority of the strain isolated seems to belong to the genera Pseudomonas and Corynebacterium. All strains were able to assimilate CHS-Na as a sole source of carbon and nitrogen, and accumulated clearly CHA in the culture medium. It was confirmed with the cell-free extract that the strains possessed the enzyme system which formed cyclohexanone (CHnone) from CHS-Na via CHA. It seems that the desulfation of CHS-Na to CHA is catalyzed by hydrolase, and that the deamination of CHA to CHnone is catalyzed by amine oxidase depending on oxygen.     

NEIL3-deficient bone marrow displays decreased hematopoietic capacity and reduced telomere length

Deficiency of NEIL3, a DNA repair enzyme, has significant impact on mouse physiology, including vascular biology and gut health, processes related to aging. Leukocyte telomere length (LTL) is suggested as a marker of biological aging, and shortened LTL is associated with increased risk of cardiovascular disease. NEIL3 has been shown to repair DNA damage in telomere regions in vitro. Herein, we explored the role of NEIL3 in telomere maintenance in vivo by studying bone marrow cells from atherosclerosis-prone NEIL3-deficient mice. We found shortened telomeres and decreased activity of the telomerase enzyme in bone marrow cells derived from Apoe^?/?Neil3^?/? as compared to Apoe^?/? mice. Furthermore, Apoe^?/?Neil3^?/? mice had decreased leukocyte levels as compared to Apoe^?/? mice, both in bone marrow and in peripheral blood. Finally, RNA sequencing of bone marrow cells from Apoe^?/?Neil3^?/? and Apoe^?/? mice revealed different expression levels of genes involved in cell cycle regulation, cellular senescence and telomere protection. This study points to NEIL3 as a telomere-protecting protein in murine bone marrow in vivo.     

Expression of assayable residual stem cell damage in erythroid differentiation

Summary In rodents, residual damage is inducible in hematopoietic stem cells by exposure to ionizing radiation or alkylating agents. This damage can be assayed in mice by transferring bone marrow into lethally irradiated syngeneic recipients and subsequently measuring the incremental increase of 5-(¹²⁵I)iodo-2-deoxyuridine incorporation in spleens. In this study, bone marrow from mice treated 3 weeks previously with Methylnitrosourea (50 mg/kg) or 450 rad was injected into recipients in order to determine possible residual effects of treatment on erythroid cell differentiation following stem cell seeding. Such effects were detected by a reduced amount of⁵⁹Fe incorporation into spleens, thus indicating transfer of residual stem cell damage to differentiating cells.Research supported by the U.S. Department of Energy Contract No. DE-AC-02-76CH00016     

Testosterone influences renal electrolyte excretion in SHR/y and WKY males

Background

Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme highly expressed in hematopoietic precursors from cord blood and granulocyte-colony stimulating factor mobilized peripheral blood, as well as in bone marrow from patients with acute myeloblastic leukemia. As regards human normal bone marrow, detailed characterization of ALDH⁺ cells has been addressed by one single study (Gentry et al, 2007). The goal of our work was to provide new information about the dissection of normal bone marrow progenitor cells based upon the simultaneous detection by flow cytometry of ALDH and early hematopoietic antigens, with particular attention to the expression of ALDH on erythroid precursors. To this aim, we used three kinds of approach: i) multidimensional analytical flow cytometry, detecting ALDH and early hematopoietic antigens in normal bone marrow; ii) fluorescence activated cell sorting of distinct subpopulations of progenitor cells, followed by in vitro induction of erythroid differentiation; iii) detection of ALDH⁺ cellular subsets in bone marrow from pure red cell aplasia patients.

Results

In normal bone marrow, we identified three populations of cells, namely ALDH⁺CD34⁺, ALDH^-CD34⁺ and ALDH⁺CD34^- (median percentages were 0.52, 0.53 and 0.57, respectively). As compared to ALDH^-CD34⁺ cells, ALDH⁺CD34⁺ cells expressed the phenotypic profile of primitive hematopoietic progenitor cells, with brighter expression of CD117 and CD133, accompanied by lower display of CD38 and CD45RA. Of interest, ALDH⁺CD34^- population disclosed a straightforward erythroid commitment, on the basis of three orders of evidences. First of all, ALDH⁺CD34^- cells showed a CD71^bright, CD105⁺, CD45^- phenotype. Secondly, induction of differentiation experiments evidenced a clear-cut expression of glycophorin A (CD235a). Finally, ALDH⁺CD34^- precursors were not detectable in patients with pure red cell aplasia (PRCA).

Conclusion

Our study, comparing surface antigen expression of ALDH⁺/CD34⁺, ALDH^-/CD34⁺ and ALDH⁺/CD34^- progenitor cell subsets in human bone marrow, clearly indicated that ALDH⁺CD34^- cells are mainly committed towards erythropoiesis. To the best of our knowledge this finding is new and could be useful for basic studies about normal erythropoietic differentiation as well as for enabling the employment of ALDH as a red cell marker in polychromatic flow cytometry characterization of bone marrow from patients with aplastic anemia and myelodysplasia.     

Methotrexate chemotherapy–induced damages in bone marrow sinusoids: An in vivo and in vitro study

Chemotherapeutic agents are very well evident extrinsic stimuli for causing damage to endothelial cells. Methotrexate is an antimetabolite commonly used to treat solid tumours and paediatric cancers. However, studies on the effect(s) of methotrexate on bone marrow microvascular system are inadequate. In the current study, we observed a significant bone marrow microvascular dilation following methotrexate therapy in rats, accompanied by apoptosis induction in bone marrow sinusoidal endothelial cells, and followed by recovery of bone marrow sinusoids associated with increased proliferation of remaining bone marrow sinusoidal endothelial cells. Our in vitro studies revealed that methotrexate is cytotoxic for cultured sinusoidal endothelial cells and can also induce apoptosis which is associated with upregulation of expression ratio of Bax and Bcl-2 genes and Bax/Bcl-2 expression ratio. Furthermore, it was shown that methotrexate can negatively affect proliferation of cultured sinusoidal endothelial cells and also inhibit their abilities of migration and formation of microvessel like tubes. The data from this study indicates that methotrexate can cause significant bone marrow sinusoidal endothelium damage in vivo and induce apoptosis and inhibit proliferation, migration and tube-forming abilities of sinusoidal endothelial cells in vitro.     

Feeder cells enhance oncolytic and proliferative activity of long-term human bone marrow interleukin-2 cultures and induce different lymphocyte subsets

Summary The effect of feeder cells on oncolytic activity of lymphocyte subsets and their growth was evaluated in long-term human bone marrow interleukin-2 (IL-2) cultures. Two B-lymphoblastoid cell lines (Daudi and Epstein-Barr-virus-transformed BSM) and two human leukemias, AML-M5, were used as feeder cells. The most prominent effects were seen in cultures stimulated with Daudi cells. In these cultures, cytotoxic activity was 100–1000 times increased against a broad range of target cells and the total cellular expansion was more than 40 times higher than in control cultures. This Daudi-related effect appeared to be mediated by natural killer (NK) cells, since cellular expansion occurred mostly in the CD16⁺ and CD56⁺ CD3^– NK cell subset. In cultures stimulated with BSM and acute myelogenous leukemia (AML) feeder cells, the increase in proliferation was similar, but the enhancement of cytotoxicity, even though significant, was less prominent. Although all feeder cells were effective in stimulation of bone marrow reactivity, the highest cytotoxicity was always observed with feeder cells autologous to the targets, indicating some degree of specificity. This was especially evident in cultures stimulated with autologous versus allogeneic AML feeder cells. In contrast to Daudistimulated IL-2 cultures, in which the highest expansion of CD3^– CD56⁺ NK cells was observed, in BSM and AML cultures, the CD3⁺ CD56^+/- T cell subsets were more prolific. This indicates that the response and phenotypic heterogeneity of bone marrow cultures depends on the type of feeder cells used. This observation indicates that the preferential stimulation of a pertinent lymphocyte subset for therapeutic purposes may be possible.Recipient of Florence Maude Thomas Cancer Research Professorship     

Bone marrow derived cells in the tumour microenvironment contain cells with primitive haematopoietic phenotype

Infiltration of bone marrow derived cells is part of the angiogenic switch required for uncontrolled tumour growth. However, the nature of the tumour-infiltrating cells from bone marrow has not been fully elucidated. To investigate the phenotype of bone marrow derived cells within a tumour, we employed the Lewis lung carcinoma (LLC) murine tumour model. We followed bone marrow derivation of tumour-infiltrating cells through transplantation of CD45.2 bone marrow cells into pre-irradiated CD45.1 mice. We found robust CD45.2 donor type chimerism in bone marrow and blood of CD45.1 recipient tumour-bearing mice. Flow cytometric analysis of LLC tumours showed, in addition to previously described pro-angiogenic CD45⁺VEGFR2⁺‘endothelial progenitor cells’ (EPC), or CD45⁺Tie2⁺‘Tie2-expressing monocytes’ (TEM), incorporation of donor type lineage marker negative (Lin⁻) and Lin⁻Sca1⁺ undifferentiated haematopoietic cell types. Immunohistochemical analysis confirmed the extravasal location of the primitive haematopoietic cells. Flow-cytometric sorting of bone marrow cells and subsequent analysis in haematopoietic colony-forming assays revealed that cells with a Lin⁻Sca1⁺ phenotype, which were initially negative for VEGFR2 and Tie2, gave rise to VEGFR2⁺ and/or Tie2⁺ cells. Moreover, Lin⁻ bone marrow cells pre-labelled with the membrane dye PKH26 (a red fluorochrome) and transplanted i.v. into tumour-bearing mice were found to extravasate and incorporate into LLC tumours within 24 hrs. Thus, primitive haematopoietic precursors which are thought to be precursors of EPC and TEMs, constitute a part of the tumour microenvironment. This makes them an attractive target cell population for tumour-directed cellular therapies.     

5-methyltetrahydrofolate homocysteine cobalamin methyltransferase in human bone marrow and its relationship to pernicious anemia

Dialyzed extracts from human bone marrow catalyze [5-¹⁴C]methyltetrahydrofolate homocysteine transmethylation at slow but significant rates which can be detected by using substrate with a very high specific radioactivity. Enzymatic activity is associated with nucleated marrow cells rather than mature, nondividing erythrocytes. Extract transmethylase activities in 15 marrow specimens from patients without B-12 deficiency ranged from 157–1020 pmoles of [Me-¹⁴C]methionine formed/hr/10⁷ nucleated cells. Catalysis is dependent on S-adenosyl-l-methionine and a flavin-reducing system, typical for the presence of a cobalamin (B-12) methyltransferase. No in vitro requirement for exogenous B-12 was observed except for the marrow extracts from two patients known to be B-12 deficient. One of these extracts was markedly stimulated by methyl-B-12 indicative that mostly apomethyltransferase was present. These tracer assays with cell-free extracts provide the first direct evidence that human bone marrow contains B-12 methyltransferase; they also afford further evidence for a 5-methyltetrahydrofolate trap in B-12 deficiency with its associated megaloblastic anemia. In addition, we have observed that in normal peripheral blood leukocytes the mononuclear fraction contains 10–30 times as much B-12 methyltransferase per nucleated cell as the polymorphonuclear granulocyte fraction.     

Bone Marrow Cell Recruitment to the Brain in the Absence of Irradiation or Parabiosis Bias

The engraftment of bone marrow-derived cells has been described not only during diseases of the central nervous system (CNS) but also under healthy conditions. However, previous studies pointing to an ample bone marrow cell engraftment used irradiation-induced bone marrow chimeras that evoked severe alterations of the CNS micromilieu including disturbances of the blood brain barrier (BBB), damage of endothelial cells and local induction of proinflammatory cytokines. On the other hand, parabiosis experiments using temporarily joined circulatory systems generally yielded low levels of myeloid cell chimerism thereby potentially underestimating bone marrow cell turnover with the CNS. To avoid these drawbacks we established a protocol using the alkylating agent busulfan prior to allogenic bone marrow transplantation from CX₃CR1^GFP/+ donors. This regimen resulted in a stable and high peripheral myeloid chimerism, significantly reduced cytokine induction and preserved BBB integrity. Importantly, bone marrow cell recruitment to the CNS was strongly diminished under these conditions and only weakly enhanced during local neurodegeneration induced by facial nerve axotomy. These results underscore the requirement of local CNS conditioning for efficient recruitment of bone marrow cells, establish busulfan as an alternative treatment for studying bone marrow chimeras and suggest a critical re-evaluation of earlier chimeric studies involving irradiation or parabiosis regimens.     

Feasibility and efficacy of bone tissue engineering using human bone marrow stromal cells cultivated in serum-free conditions

Current standard techniques for bone tissue engineering utilize ex vivo expanded osteogenic cells. However, ex vivo expansion requires serum, which may hinder clinical applications. Here, we report the feasibility and efficacy of bone tissue engineering with human bone marrow stromal cells (BMSCs) expanded in serum-free conditions. Bone marrow was aspirated from 4 healthy donors and adherent cells were cultured in either serum-free medium (STEMPRO^® MSC SFM) or conventional serum-containing medium (α-MEM supplemented with 10% serum). Efficacy of expansion was greater in serum-free medium. Phenotypically, serum-free expanded BMSCs were smaller in cell-size and showed expression of CD105⁺⁺ and CD146^dim. After osteogenic induction, serum-free expanded BMSCs showed lower alkaline phosphatase activity. However, they showed higher responsiveness to induction. In vivo bone-forming ability was also confirmed. In conclusion, bone tissue engineering with serum-free expanded BMSCs is feasible and as efficient as that obtained with BMSCs expanded in conventional serum-containing medium.