Unsymmetrical Pd(II) Pincer Complexes with Benzothiazole and Thiocarbamate Flanking Units: Expedient Solvent-Free Synthesis and Anticancer Potential.

Driven by the growing threat of cancer, many research efforts are directed at developing new chemotherapeutic agents, where the central role is played by transition metal complexes. The proper ligand design serves as a key factor to unlock the anticancer potential of a particular metal center. Following a recent trend, we have prepared unsymmetrical pincer ligands that combine benzothiazole and thiocarbamate donor groups. These compounds are shown to readily undergo direct cyclopalladation, affording the target S,C,N-type Pd(II) pincer complexes both in solution and in the absence of a solvent. The solid-phase strategy provided the complexes in an efficient and ecologically friendly manner. The resulting palladacycles are fully characterized using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy and, in one case, by single-crystal X-ray diffraction (XRD). The solvent-free reactions are additionally analyzed by powder XRD. The pincer complexes exhibit remarkable cytotoxicity against several solid and blood cancer cell lines, including human colorectal carcinoma (HCT116), breast cancer (MCF7), prostate adenocarcinoma (PC3), chronic myelogenous leukemia (K562), multiple plasmacytoma (AMO1), and acute lymphoblastic leukemia (H9), with the dimethylamino-substituted derivative being particularly effective. The latter also induced an appreciable level of apoptosis in both parental and doxorubicin-resistant cells K562 and K562/iS9, vindicating the high anticancer potential of this type of palladacycles.

(Aminoalkyl)diphenylphosphine sulfides: synthesis and application as building blocks in the design of multidentate ligands for cytotoxic Pd(II) complexes.

Amino-functionalized phosphoryl compounds are among the most useful molecular scaffolds in medicinal chemistry, while the potential of their thiophosphorylated analogs, especially those having an alkylamino moiety, is still uncovered. This is mainly due to the lack of convenient synthetic routes to these organophosphorus derivatives. To address this issue, we have suggested the facile approaches to α-(aminomethyl)- and substituted/unsubstituted α-(aminobenzyl)diphenylphosphine sulfides based on either the sequential transformations of (hydroxymethyl)diphenylphosphine sulfide, with the Staudinger reaction of an azide derivative as the key stage, or the addition of Ph2P(S)H to hydrobenzamides followed by the acid hydrolysis. The compounds obtained were reacted with picolinyl chloride to yield functionalized amides which readily underwent direct cyclopalladation, resulting in new representatives of non-classical N-metalated Pd(II) pincer complexes. The latter exhibit promising cytotoxic activity against several human cancer cell lines and apoptosis inducing ability along with the remarkable cytotoxic effects on doxorubicin-resistant cell sublines.

Modulation of the Cytotoxic Properties of Pd(II) Complexes Based on Functionalized Carboxamides Featuring Labile Phosphoryl Coordination Sites.

Platinum-based drugs are commonly recognized as a keystone in modern cancer chemotherapy. However, intrinsic and acquired resistance as well as serious side effects often caused by the traditional Pt(II) anticancer agents prompt a continuous search for more selective and efficient alternatives. Today, significant attention is paid to the compounds of other transition metals, in particular those of palladium. Recently, our research group has suggested functionalized carboxamides as a useful platform for the creation of cytotoxic Pd(II) pincer complexes. In this work, a robust picolinyl- or quinoline-carboxamide core was combined with a phosphoryl ancillary donor group to achieve hemilabile coordination capable of providing the required level of thermodynamic stability and kinetic lability of the ensuing Pd(II) complexes. Several cyclopalladated derivatives featuring either a bi- or tridentate pincer-type coordination mode of the deprotonated phosphoryl-functionalized amides were selectively synthesized and fully characterized using IR and NMR spectroscopy as well as X-ray crystallography. The preliminary evaluation of the anticancer potential of the resulting palladocycles revealed a strong dependence of their cytotoxic properties on the binding mode of the deprotonated amide ligands and demonstrated certain advantages of the pincer-type ligation.

Effects of Dendrimer-microRNA Nanoformulations against Glioblastoma Stem Cells.

Glioblastoma is a rapidly progressing tumor quite resistant to conventional treatment. These features are currently assigned to a self-sustaining population of glioblastoma stem cells. Anti-tumor stem cell therapy calls for a new means of treatment. In particular, microRNA-based treatment is a solution, which in turn requires specific carriers for intracellular delivery of functional oligonucleotides. Herein, we report a preclinical in vitro validation of antitumor activity of nanoformulations containing antitumor microRNA miR-34a and microRNA-21 synthetic inhibitor and polycationic phosphorus and carbosilane dendrimers. The testing was carried out in a panel of glioblastoma and glioma cell lines, glioblastoma stem-like cells and induced pluripotent stem cells. We have shown dendrimer-microRNA nanoformulations to induce cell death in a controllable manner, with cytotoxic effects being more pronounced in tumor cells than in non-tumor stem cells. Furthermore, nanoformulations affected the expression of proteins responsible for interactions between the tumor and its immune microenvironment: surface markers (PD-L1, TIM3, CD47) and IL-10. Our findings evidence the potential of dendrimer-based therapeutic constructions for the anti-tumor stem cell therapy worth further investigation.

Pincer-dipeptide and pseudodipeptide conjugates: Synthesis and bioactivity studies.

Following a recent trend on the application of different pincer scaffolds for the development of new metal-based antitumor agents, in this work, dipeptides and dipeptide surrogates based on picolinyl- and 4-chloropicolinylamides with S-donor amino acid residues (cysteine, homocysteine, or methionine) bearing glycinate, alaninate, or phosphonate moieties either at the C-terminus or in the S-donor side arm have been designed as nonclassical pincer ligands with central amide units and shown to smoothly undergo site-selective direct cyclopalladation under mild conditions, affording the target Pd(II) pincer complexes in good to high yields. The realization of S,N,N-coordination through the sulfur atom of the thioether group and nitrogen atoms of the pyridine and deprotonated amide units was unambiguously confirmed using different NMR techniques (1H, 13C, 31P, and 2D NMR methods, including 1H15N HMBC) and IR spectroscopy; the structure of one representative was elucidated by X-ray crystallography. The resulting pincer-(pseudo)dipeptide conjugates were screened for cytotoxicity against several cancer cell lines and noncancerous human embryonic kidney cells and at least some of them provided an appreciable level of activity comparable to that of cisplatin. The S-modified homocysteine-based derivatives exhibited also significant antiproliferative effects against doxorubicin-resistant transformed breast cells HBL100/Dox, implying the possibility of overcoming drug resistance. The complexes can induced apoptosis but did not affect mitochondria. The comparative DNA/protein binding studies of one of the most active pincer-(pseudo)dipeptide conjugates with the monoamino acid-based prototype revealed certain advantages of the former and gave further insights into the potential of this type of palladium-based antitumor agents.

In Vitro Validation of the Therapeutic Potential of Dendrimer-Based Nanoformulations against Tumor Stem Cells.

Tumor cells with stem cell properties are considered to play major roles in promoting the development and malignant behavior of aggressive cancers. Therapeutic strategies that efficiently eradicate such tumor stem cells are of highest clinical need. Herein, we performed the validation of the polycationic phosphorus dendrimer-based approach for small interfering RNAs delivery in in vitro stem-like cells as models. As a therapeutic target, we chose Lyn, a member of the Src family kinases as an example of a prominent enzyme class widely discussed as a potent anti-cancer intervention point. Our selection is guided by our discovery that Lyn mRNA expression level in glioma, a class of brain tumors, possesses significant negative clinical predictive value, promoting its potential as a therapeutic target for future molecular-targeted treatments. We then showed that anti-Lyn siRNA, delivered into Lyn-expressing glioma cell model reduces the cell viability, a fact that was not observed in a cell model that lacks Lyn-expression. Furthermore, we have found that the dendrimer itself influences various parameters of the cells such as the expression of surface markers PD-L1, TIM-3 and CD47, targets for immune recognition and other biological processes suggested to be regulating glioblastoma cell invasion. Our findings prove the potential of dendrimer-based platforms for therapeutic applications, which might help to eradicate the population of cancer cells with augmented chemotherapy resistance. Moreover, the results further promote our functional stem cell technology as suitable component in early stage drug development.

Phylogeny, Structure, Functions, and Role of AIRE in the Formation of T-Cell Subsets.

It is well known that the most important feature of adaptive immunity is the specificity that provides highly precise recognition of the self, altered-self, and non-self. Due to the high specificity of antigen recognition, the adaptive immune system participates in the maintenance of genetic homeostasis, supports multicellularity, and protects an organism from different pathogens at a qualitatively different level than innate immunity. This seemingly simple property is based on millions of years of evolution that led to the formation of diversification mechanisms of antigen-recognizing receptors and later to the emergence of a system of presentation of the self and non-self antigens. The latter could have a crucial significance because the presentation of nearly complete diversity of auto-antigens in the thymus allows for the "calibration" of the forming repertoires of T-cells for the recognition of self, altered-self, and non-self antigens that are presented on the periphery. The central role in this process belongs to promiscuous gene expression by the thymic epithelial cells that express nearly the whole spectrum of proteins encoded in the genome, meanwhile maintaining their cellular identity. This complex mechanism requires strict control that is executed by several transcription factors. One of the most important of them is AIRE. This noncanonical transcription factor not only regulates the processes of differentiation and expression of peripheral tissue-specific antigens in the thymic medullar epithelial cells but also controls intercellular interactions in the thymus. Besides, it participates in an increase in the diversity and transfer of presented antigens and thus influences the formation of repertoires of maturing thymocytes. Due to these complex effects, AIRE is also called a transcriptional regulator. In this review, we briefly described the history of AIRE discovery, its structure, functions, and role in the formation of antigen-recognizing receptor repertoires, along with other transcription factors. We focused on the phylogenetic prerequisites for the development of modern adaptive immunity and emphasized the importance of the antigen presentation system.

Mechanochemistry for the synthesis of non-classical N-metalated palladium(II) pincer complexes.

The peculiarities of cyclopalladation of a series of non-classical pincer-type ligands based on monothiooxalyl amides bearing ancillary N- or S-donor groups in the amide units have been scrutinized both under conditions of conventional solution-based synthesis and in the absence of a solvent according to a solid-phase methodology including mechanochemical activation. Grinding the functionalized monothiooxamides with PdCl2(NCPh)2 in a mortar or vibration ball mill is shown to serve as an efficient and green alternative to the synthesis of these complex metal-organic systems in solution that can offer such advantages as the absence of any auxiliary and significant rate and yield enhancement, especially for the challenging ligands. The realization of S,N,N- or S,N,S-monoanionic tridentate coordination in the resulting pincer complexes has been confirmed by multinuclear NMR (including 2D NMR) and IR spectroscopy and, in some cases, X-ray diffraction. The course and outcome of the solid-phase reactions have been studied by a combination of different spectroscopic methods as well as SEM/EDS analysis. The preliminary evaluation of cytotoxic activity against several human cancer cell lines has revealed the high potency of some of the cyclopalladated derivatives obtained, rendering further development of solvent-free synthetic routes to this type of complexes very urgent.

Immune Equilibrium Depends on the Interaction Between Recognition and Presentation Landscapes.

In this review, we described the structure and organization of antigen-recognizing repertoires of B and T cells from the standpoint of modern immunology. We summarized the latest advances in bioinformatics analysis of sequencing data from T and B cell repertoires and also presented contemporary ideas about the mechanisms of clonal diversity formation at different stages of organism development. At the same time, we focused on the importance of the allelic variants of the HLA genes and spectra of presented antigens for the formation of T-cell receptors (TCR) landscapes. The main idea of this review is that immune equilibrium and proper functioning of immunity are highly dependent on the interaction between the recognition and the presentation landscapes of antigens. Certain changes in these landscapes can occur during life, which can affect the protective function of adaptive immunity. We described some mechanisms associated with these changes, for example, the conversion of effector cells into regulatory cells and vice versa due to the trans-differentiation or bystander effect, changes in the clonal organization of the general TCR repertoire due to homeostatic proliferation or aging, and the background for the altered presentation of some antigens due to SNP mutations of MHC, or the alteration of the presenting antigens due to post-translational modifications. The authors suggest that such alterations can lead to an increase in the risk of the development of oncological and autoimmune diseases and influence the sensitivity of the organism to different infectious agents.

The Effect of Cucurbit[7]uril on the Antitumor and Immunomodulating Properties of Oxaliplatin and Carboplatin.

Cucurbit[7]uril (CB[7]) is a molecular container that may form host-guest complexes with platinum(II) anticancer drugs and modulate their efficacy and safety. In this paper, we report our studies of the effect of CB[7]-oxaliplatin complex and the mixture of CB[7] and carboplatin (1:1) on viability and proliferation of a primary cell culture (peripheral blood mononuclear cells), two tumor cell lines (B16 and K562) and their activity in the animal model of melanoma. At the same time, we studied the impact of platinum (II) drugs with CB[7] on T cells and B cells in vitro. Although the stable CB[7]-carboplatin complex was not formed, the presence of cucurbit[7]uril affected the biological properties of carboplatin. In vivo, CB[7] increased the antitumor effect of carboplatin, but, at the same time, increased its acute toxicity. Compared to free oxaliplatin, its complex with CB[7] shows a greater cytotoxic effect on tumor cell lines B16 and K562, while in vivo, the effects of the free drug and encapsulated drug were comparable. However, in vivo studies also demonstrated that the encapsulation of oxaliplatin in CB[7] lowered the toxicity of the drug.

Palladium(II) Pincer Complexes of Functionalized Amides with S-Modified Cysteine and Homocysteine Residues: Cytotoxic Activity and Different Aspects of Their Biological Effect on Living Cells.

In the search for potential new metal-based antitumor agents, two series of nonclassical palladium(II) pincer complexes based on functionalized amides with S-modified cysteine and homocysteine residues have been prepared and fully characterized by 1D and 2D NMR (1H, 13C, COSY, HMQC or HSQC, 1H-13C, and 1H-15N HMBC) and IR spectroscopy and, in some cases, X-ray diffraction. Most of the resulting complexes exhibit a high level of cytotoxic activity against several human cancer cell lines, including colon (HCT116), breast (MCF7), and prostate (PC3) cancers. Some of the compounds under consideration are also efficient in both native and doxorubicin-resistant transformed breast cells HBL100, suggesting the prospects for the creation of therapeutic agents based on the related compounds that would be able to overcome drug resistance. An analysis of different aspects of their biological effects on living cells has revealed a remarkable ability of the S-modified derivatives to induce cell apoptosis and efficient cellular uptake of their fluorescein-conjugated counterpart, confirming the high anticancer potential of Pd(II) pincer complexes derived from functionalized amides with S-donor amino acid pendant arms.

Highly Cytotoxic Palladium(II) Pincer Complexes Based on Picolinylamides Functionalized with Amino Acids Bearing Ancillary S-Donor Groups.

The reactions of picolinyl and 4-chloropicolinyl chlorides with methyl esters of S-methyl-l-cysteine, l- and d-methionine, and l-histidine afforded a series of functionalized carboxamides, which readily formed pincer-type complexes upon interaction with PdCl2(NCPh)2 in solution under mild conditions. The direct cyclopalladation of the ligands derived was also accomplished in the solid phase, in particular, mechanochemically, although it was complicated by the partial deactivation of the starting amides. The resulting complexes with 5,5- and 5,6-membered fused metallocycles were fully characterized by IR and NMR spectroscopy, including variable-temperature and 2D-NMR studies. In the case of some cysteine- and methionine-based derivatives, the realization of κ3-N,N,S-coordination was supported by X-ray diffraction. The cytotoxic effects of these complexes were examined on HCT116, MCF7, and PC3 human cancer cell lines as well as HEK293 as a representative of normal cells. The comparative studies allowed us to determine that the presence of the sulfide ancillary donor group is crucial for cytotoxic activity of this type of Pd(II) complexes. The main structure-activity relationships and the most promising palladocycles were outlined. The additional studies by gel electrophoresis revealed that 4-chloropicolinyl derivatives, despite the nature of an amino acid, can bind with DNA and inhibit topoisomerase I activity.

Chemical and biological properties of a supramolecular complex of tuftsin and cucurbit[7]uril.

Cucurbit[7]uril (CB7) is an uncharged and water-soluble macrocyclic host. CB7 binds to doubly protonated tuftsin, which is the tetrapeptide Thr-Lys-Pro-Arg, with moderate affinity (Ka=2.1×103M-1). In this study, the host-guest complexation was confirmed by fluorescence titration. This affinity would allow for easy release of the peptide under physiological conditions. According to density functional theory calculations, the structural binding motif involves hydrogen bonding. The most energetically stable form had the Arg side chain inside the CB7 cavity. The effects of the tuftsin-CB7 complex on the proliferation and cytokine activity of immune cells were studied. The complex had broader spectrum immunomodulation than free peptides, and caused statistically significant (p<0,05) changes in cytokine production (tumor necrosis factor-α, interleukin-2, interferon-γ, and interleukin-10) by mononuclear cells. By contrast, the free peptide only activated tumor necrosis factor-α production.

Clinical experience with autologous M2 macrophages in children with severe cerebral palsy.

Stem cell-based therapy is considered to be a new approach for the treatment of cerebral palsy (CP). Given the potent anti-inflammatory activity and high regenerative potential of M2 macrophages, these cells may be an alternative source for cell transplantation. To evaluate the safety and efficacy of autologous M2 macrophages, we conducted a pilot clinical trial in 21 children with severe CP. The primary outcome measure was safety, which included assessment of mortality of any cause, immediate adverse reactions, and serious adverse effects and comorbidities during 5-year follow-up. The secondary outcome measure was functional improvement in Gross Motor Function Measure (66-item GMFM) test, Peabody Developmental Motor Scale-Fine Motor (PDMS-FM) test, Ashworth scale, MRC scale, and an easy-to-understand questionnaire for evaluation of cognitive functions in our modification. Intradural injection of M2 cells (in mean dose of 0.8 × 10(6)/kg) into the lumbar spinal area did not induce any serious adverse events. No cases of mortality, psychomotor worsening, exacerbation of seizures, and long-term comorbidities, including tumors, were observed during a 5-year follow-up. After 3 months, GMFM score increased from 13.7 ± 7.8 to 58.6 ± 14.6, PDMS-FM score improved from 0.76 ± 0.42 to 5.05 ± 0.97, and the Ashworth score decreased from 3.8 ± 0.21 to 3.3 ± 0.24. Along with gross and fine motor function enhancement, an improvement of cognitive activity (from 1.62 ± 0.41 to 4.05 ± 0.64, according to questionnaire assessment) and reduction of seizure syndrome were registered as well. The neurological improvements did not diminish during the 5-year follow-up period. The data obtained suggest that cell therapy based on M2 macrophages is safe, does not induce early adverse effects and long-term comorbidities, and is accompanied with a significant improvement of motor and cognitive activities in severe CP patients. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.

Rapid Recovery from Chronic PRCA by MSC Infusion in Patient after Major ABO-Mismatched alloSCT.

Pure red cell aplasia (PRCA) is a rare complication in recipients of allogenic stem cell from ABO incompatible donors. It is characterized by reticulocytopenia and by an absence of red cell cell precursors in the bone marrow. Despite close isohemagglutinins monitoring and standard immunosupressive treatment in these patients prolong PRCA are still associated with severe transfusion dependence. We report the case of a 31 yr old male patient who underwent HLA-matched ABO-mismatched allo-SCT and developed resistance PRCA despite conventional immunosupressive therapy and prophylaxis cotrasplantation of bone marrow derived MSC at day 0. He responded dramatically to therapy with adipose tissue derived mesenchymal stem cells from HSC donors and continued to be transfusion-independent and AML-disease free. This method of the PRCA therapy of deserves further investigation.

High-dose immunosuppressive therapy with autologous hematopoietic stem cell transplantation as a treatment option in multiple sclerosis.

High-dose immunosuppressive therapy (HDIT) with autologous hematopoietic stem cell transplantation (auto-HSCT) is a new and promising approach to the treatment of multiple sclerosis (MS) patients because currently there are no effective treatment methods for this disease. In this article, we present results of a prospective clinical study of efficacy of HDIT + auto-HSCT in MS patients. The following treatment strategies were employed in the study: "early," "conventional," and "salvage/late" transplantation. Fifty patients with various types of MS were included in this study. No toxic deaths were reported among 50 MS patients; transplantation procedure was well-tolerated by the patients. The efficacy analysis was performed in 45 patients. Twenty-eight patients achieved an objective improvement of neurological symptoms, defined as at least 0.5-point decrease in the Expanded Disability Status Scale (EDSS) score as compared to the baseline and confirmed during 6 months, and 17 patients had disease stabilization (steady EDSS level as compared to the baseline and confirmed during 6 months). The progression-free survival at 6 years after HDIT + auto-HSCT was 72%. Magnetic resonance imaging data were available in 37 patients before transplantation showing disease activity in 43.3%. No active, new, or enlarging lesions were registered in patients without disease progression. In conclusion, HDIT + auto-HSCT suggests positive results in management of patients with different types of MS. Identification of treatment strategies based on the level of disability, namely "early," "conventional," and "salvage/late" transplantation, appears to be feasible to improve treatment outcomes.

Development of a novel protocol for RT-multiplex PCR to detect diarrheal viruses among infants and children with acute gastroenteritis in Eastern Russia.

Viral gastroenteritis is one of the most common illnesses in humans worldwide and it has a great impact on people. Recently, we reported three RT-multiplex PCR assays termed A, B and C that could detect three groups of diarrheal viruses; group A, B and C rotaviruses and adenovirus [Phan et al., J Med Virol 2004; 74:173-9]; norovirus GI and GII, sapovirus and astrovirus [Yan et al., J Virol Meth 2003; 114:37-44]; enteroviruses, hepatitis A and E viruses and influenza A virus [Phan et al., Arch Virol 2005; 1175-85], respectively. In the present study, we developed a novel protocol with a small volume of reaction mixture for RT and PCR products (only 8 microl and 11 microl, respectively) that can amplify genomes of target viruses simultaneously. A total of 100 fecal specimens from infants and children with acute gastroenteritis in Birobiclzhan city, Eastern Russia, were collected during November 2003 and March 2004 and tested for the presence of those viruses by the novel RT-multiplex PCR protocol. Group A rotavirus was the most prevalent (67%), followed by norovirus GII (4%), group C rotavirus (1%), and sapovirus (1%). Interestingly, one fecal specimen turned out to be positive for hepatitis A virus. The sensitivity and specificity of RT-multiplex PCR assays with a novel protocol demonstrated a strong validation against the previously published RT-multiplex PCR. The findings clearly indicated that this novel protocol is simple and cost-effective to investigate the molecular epidemiology of acute gastroenteritis caused by diarrheal viruses. This report is the first, to our knowledge, detecting hepatitis A virus in feces from diarrheal infants and children in Eastern Russia.

Tolerability of N-chlorotaurine in chronic rhinosinusitis applied via yamik catheter.

OBJECTIVES: A rational approach in the treatment of chronic rhinosinusitis (CRS) is the intranasal application of antiseptic agents, due to the pathogenetic role of bacteria and fungi. N-Chlorotaurine (NCT), a mild endogenous oxidant with broad-spectrum antimicrobial activity, has been tested for the first time in CRS. METHODS: This one-arm phase IIa clinical study is the first step in the clinical development of this promising substance for local therapy of CRS. The nasal and paranasal cavities of 12 patients were rinsed with 10-20 ml of 1% aqueous NCT solution, applied via a novel catheter system (YAMIK). Treatment consisted of three lavages per week for 4 weeks. RESULTS: NCT caused neither alterations of the mucosa nor burning pain during application. Nevertheless, the insertion of the catheter, the insufflation of the posterior cuff and the overpressure inside the sinuses after infiltration led to moderate pain in some patients. Mucosal swelling decreased in all subjects, nasal breathing could be improved in nine patients and impaired olfaction in seven. Polyps did not disappear within the 1-month period of the study. CONCLUSIONS: The good tolerability and possible beneficial effects of NCT encourage its further investigation in CRS. Despite some limitations the YAMIK catheter proved to be a convenient and safe device for rinsing the nasal and paranasal sinuses.

Exposure to nicotine during gestation interferes with the colonization of fetal bone marrow by hematopoietic stem/progenitor cells.

Environmental factors, including cigarette smoke components, can cross the placental barrier and accumulate in amniotic fluid and fetal tissue, and, therefore, interfere with the normal course of ontogenesis. Although cigarette smoke contains numerous compounds, the most adverse effects on mammalian tissues have been associated with nicotine. The aim of this study was to investigate the effect of intrauterine exposure to nicotine on hematopoiesis during fetal development and postpartum. Intrauterine exposure of mice to nicotine resulted in a more than two-fold reduction of the delayed- type hypersensitivity (DTH) response and a 2.5-fold decrease in the number of plaque forming cell (PFC) in offspring after 1 month of postnatal life, and correlated with low counts of mature lymphocytes and lymphoid progenitors in hematopoietic tissues. Neonates exposed to nicotine during gestation showed a significant decrease in the number of bone marrow hematopoietic progenitors, as measured by colony-forming unit (CFU) and long-term culture initiating cell (LTC-IC) assays, and decreased concentration of interleukin-6 (IL-6) in their serum. Analysis of the fetal bone marrow (E15) obtained from nicotine-exposed fetuses demonstrated a lower number of hematopoietic progenitors, whereas their number in the fetal liver was not significantly changed. Our data provide evidence that by targeting the nicotinic acetylcholine receptor (nAChR) nicotine interferes with the fetal development of the hematopoietic system. Inferior colonization of the fetal bone marrow by hematopoietic stem/progenitor cells (HSPC) subsequently results in an imbalance of mature blood and immune cell production after birth.