Quantum dot labeling and tracking of human leukemic, bone marrow and cord blood cells

Current Advances in the Biomedical Applications of Quantum Dots: Promises and Challenges

Quantum dots (QDs) are a type of nanoparticle with exceptional photobleaching-resistant fluorescence. They are highly sought after for their potential use in various optical-based biomedical applications. However, there are still concerns regarding the use of quantum dots. As such, much effort has been invested into understanding the mechanisms behind the behaviors of QDs, so as to develop safer and more biocompatible quantum dots. In this mini-review, we provide an update on the recent advancements regarding the use of QDs in various biomedical applications. In addition, we also discuss# the current challenges and limitations in the use of QDs and propose a few areas of interest for future research.

CdSe- Reduced graphene oxide nanocomposite toxicity alleviation via V2O5 shell formation over CdSe core: in vivo and in vitro studies

The present article demonstrates the synthesis of the nanocomposite of reduced graphene oxide (rGO) with CdSe and CdSe/V₂O₅ core/shell quantum dots by a two-step facile synthesis approach and subsequently studies their relative biocompatibility in different cells. Various characterization techniques have been applied including transmission electron microscopy (TEM), an x-ray diffractometer (XRD) and Raman spectroscopy to confirm the successful formation of CdSe-rGO and CdSe/V₂O₅-rGO nanocomposites. The average sizes of CdSe and CdSe/V₂O₅ QDs have found to be ∼3 and 5.5 nm, respectively with a good dispersion over the surface of rGO nanosheets. A crystal phase change has occurred during the formation of the V₂O₅ shell over the surface of CdSe QDs and confirmed through XRD. Raman spectroscopy has shown some useful insight of the surface state of CdSe and consequent changes in the surface with V₂O₅ shell growth. Further, MTT and cell growth assays have been performed to analyze their biocompatibility in A549 and Hela cells with various concentrations of as-synthesized materials. Our results demonstrate the toxicity of CdSe-rGO nanocomposite to be substantially reduced by the growth of the V₂O₅ shell. The in vivo studies in Drosophila show a remarkable decrease in the reactive oxygen species (ROS) and apoptosis levels for a CdSe/V₂O₅-rGO composite as compared to a CdSe-rGO nanocomposite, which paves a promising pathway for the CdSe/V₂O₅-rGO nanocomposite to be used as an efficient biocompatible material.

CdSe quantum dots evaluation in primary cellular models or tissues derived from patients

In recent years quantum dots (QDs) have risen as useful luminescent nanoparticles with multiple applications ranging from laser, image displays and biomedical applications. Here we review and discuss the studies of these nanoparticles in patient derived cellular samples or tissues, including cellular models from iPSCs from patients, biopsied and post-mortem tissue. QD-based multiplexed imaging has been proved to overcome most of the major drawbacks of conventional techniques, exhibiting higher sensitivity, reliability, accuracy and simultaneous labeling of key biomarkers. In this sense, QDs are very promising tools to be further used in clinical applications including diagnosis and therapy approaches. Analyzing the possibilities of these materials in these biological samples gives an overview of the future applications of the nanoparticles in models closer to patients and their specific disease.

Enantiopure polythiophene nanoparticles. Chirality dependence of cellular uptake, intracellular distribution and antimicrobial activity

The use of intrinsic chiral molecules opens the door to bio-imaging specific tools and to the development of target-therapy.

Expression of Tiam1 and Rac1 proteins in renal cell carcinoma and its clinical-pathological features

PURPOSE

To explore the connections between Tiam1 and Rac1 expression in renal cell carcinoma (RCC), and its pathological type, grading, invasion and metastasis.

METHODS

Tiam1 and Rac1 expression was measured in 60 specimens of RCC (including 42 clear cell cases, 12 papillary cases, and 6 chromophobe cases) and a 10-specimen control group using quantum dots IHC labeling, complete with clinical and pathological records, dated 2008 to 2014, were taken from the archives of the Department of Pathology, People's Hospital of Wuhan University. The expressions of Tiam1 and Rac1 proteins in specimens were measured using immunohistochemical (IHC) and quantum dots-labeling methods to examine their relationships to the clinical and pathological characteristics of RCC. The HIPAS-1000 software was used to quantitatively analyze on the results to obtain absorbance and positive area ratio (PAR) values, and SPSS 15.0 was used to perform single-factor analysis of variance and q verification. Spearman's rank correlation test is used to verify the correlation between absorbance and PAR of the two proteins.

RESULTS

1. QDs IHC staining. Tiam1 and Rac1 expression is high in RCC, and low in surrounding tissues (P<0.05). 2. Expression levels of both proteins show no correlation with patient sex, age, or tumor size (P>0.05), yet correlate with the differentiation, stage, and lymphatic metastasis of tumors (P<0.05). Spearman's test shows a positive correlation between the expression levels of Tiam1 and Rac1 in RCC tissues (r=0.425, P<0.05).

CONCLUSION

1. Abnormal Tiam1 and Rac1 expression may be an early molecular event in RCC, suggesting they are carcinogens related to proto-oncogenes. 2. Tiam1 and Rac1 expression levels correlate with the differentiation, stage, and lymphatic metastasis of RCC, suggesting they play important roles in its invasion and metastasis. 3. The expression levels of Tiam1 and Rac1 are positively correlated within RCC, suggesting a synergy between the two in controlling its pathogenesis and development.

Influence of heavy nanocrystals on spermatozoa and fertility of mammals

In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential for uptake of the heavy QDs. Meantime, the NCs exhibited concentration-dependent adverse effects on morphology, viability, kinetic characteristics and DNA of the spermatozoa. At low concentration of 0.1μg/mL, the NCs showed a moderate toxicity (~25% reduction in viability and motility of the spermatozoa), while remarkable toxicities were observed at higher concentrations of 1.0-100μg/mL (~67% reduction in viability and motility for 100μg/mL). Furthermore, significant in vitro DNA fragmentation of the spermatozoa was observed at CdTe concentrations ≥10μg/mL. In vivo toxicity of the NCs was found lower than the in vitro toxicity. Nevertheless, the in vivo destructive effects of the NCs still caused ~34% reduction in viability as well as motility and ~5% damages in DNA of male mice spermatozoa. These resulted in ~26% decrease in fertility and gestation of female mice, along with an overall hormone secretion during the pregnancy, and ~39% reduction in viability of pups/pregnant females.

Sustained anti-BCR-ABL activity with pH responsive imatinib mesylate loaded PCL nanoparticles in CML cells

IM–chitosan complex encapsulated poly(ε-caprolactone) (PCL) nanoparticles are proposed for their potential in enabling more intelligent controlled release and enhancing chemotherapeutic efficiency of IM.

Coupled delivery of imatinib mesylate and doxorubicin with nanoscaled polymeric vectors for a sustained downregulation of BCR-ABL in chronic myeloid leukemia

Our couple delivery strategy allowed a sustained downregulation of BCR-ABL for long times in chronic myeloid leukemia, combining two types of polymeric nanoparticles for quick and slow release of IM and DOX.

Nanomedicine: tiny particles and machines give huge gains

Nanomedicine is an emerging field that integrates nanotechnology, biomolecular engineering, life sciences and medicine; it is expected to produce major breakthroughs in medical diagnostics and therapeutics. Nano-scale structures and devices are compatible in size with proteins and nucleic acids in living cells. Therefore, the design, characterization and application of nano-scale probes, carriers and machines may provide unprecedented opportunities for achieving a better control of biological processes, and drastic improvements in disease detection, therapy, and prevention. Recent advances in nanomedicine include the development of nanoparticle (NP)-based probes for molecular imaging, nano-carriers for drug/gene delivery, multifunctional NPs for theranostics, and molecular machines for biological and medical studies. This article provides an overview of the nanomedicine field, with an emphasis on NPs for imaging and therapy, as well as engineered nucleases for genome editing. The challenges in translating nanomedicine approaches to clinical applications are discussed.

Uptake of imatinib-loaded polyelectrolyte complexes by BCR-ABL(+) cells: a long-acting drug-delivery strategy for targeting oncoprotein activity

RATIONALE & AIM

Imatinib mesylate (IM), a selective tyrosine kinase inhibitor of the oncoprotein BCR-ABL, is the 'gold standard' for patients with chronic myeloid leukemia (CML) but the drug does not eliminate CML stem cells, leading to disease relapse on drug discontinuation. At present, much effort is focused on delivery carriers that can increase the intracellular retention and antileukemic impact of IM. We previously validated IM-loaded polyelectrolyte microcapsules as effective purging agents to eradicate BCR-ABL(+) cells from CML patient autografts. The aim is to develop controlled release carriers that can increase the intracellular retention and functionality of IM in leukemia cells.

MATERIALS & METHODS

Herein, novel polyelectrolyte complexes were used as model carriers for IM in a CML cell line (KU812) and CD34(+) cells freshly isolated from patients.

RESULTS & DISCUSSION

Polyelectrolyte complexes promoted a long-acting BCR-ABL kinase inactivation that was necessary to promote apoptosis at approximately twofold lower intracellular IM dose compared with the microscale formulation polyelectrolyte microcapsules.

CONCLUSION

IM-loaded polyelectrolyte complexes can be used as more efficient delivery devices for overcoming drug resistance of BCR-ABL(+) leukemic cells.

Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

Luminescent quantum dots were synthesized using bacterially derived selenide (Se(II-)) as the precursor. Biogenic Se(II-) was produced by the reduction of Se(IV) by Veillonella atypica and compared directly against borohydride-reduced Se(IV) for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se(II-) formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic Se(II-) included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic Se(II-) is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.

Quantum dot imaging for HSP70 and HSF‑1 kinetics in SCC‑25 cells with or without leucine deprivation following heat shock

The aim of this study was to develop a quantum dot-based approach for heat shock protein 70 (HSP70) and heat shock factor 1 (HSF-1) kinetics following heat shock, and to discover approaches to thermotherapy based on disrupting the effect of activation of HSF-1 and the accumulation of HSP70 by leucine deprivation. SCC-25 cells cultured with limiting leucine or normal leucine were stressed at 42˚C for 30 min, and were cultured for 2, 4, 6, 8 and 10 h, respectively. The expression of HSP70 and HSF-1 was observed using confocal laser microscopy and semi-quantitative analysis was performed by Image-Pro Plus. At 6 h after heating, HSF-1 in cells cultured with normal leucine was activated and translocated from the cytosol to the nucleus, and the synthesis of HSP70 reached the maximum value and had a tendency to gather in the nucleus. However, in cells cultured with limiting leucine, HSF-1 activity decreased and accumulation of HSP70 was not found. Leucine deprivation results in the inactivation of HSF-1 leading to slight accumulation of HSP70 and no tendency to gather in the nucleus. Thus, HSF-1 may serve as a novel therapeutic target in the treatment of oral cancer.

Comprehensive analysis of the effects of CdSe quantum dot size, surface charge, and functionalization on primary human lung cells

The growing potential of quantum dots (QDs) in applications as diverse as biomedicine and energy has provoked much dialogue about their conceivable impact on human health and the environment at large. Consequently, there has been an urgent need to understand their interaction with biological systems. Parameters such as size, composition, surface charge, and functionalization can be modified in ways to either enhance biocompatibility or reduce their deleterious effects. In the current study, we simultaneously compared the impact of size, charge, and functionalization alone or in combination on biological responses using primary normal human bronchial epithelial cells. Using a suite of cellular end points and gene expression analysis, we determined the biological impact of each of these properties. Our results suggest that positively charged QDs are significantly more cytotoxic compared to negative QDs. Furthermore, while QDs functionalized with long ligands were found to be more cytotoxic than those functionalized with short ligands, negative QDs functionalized with long ligands also demonstrated size-dependent cytotoxicity. We conclude that QD-elicited cytotoxicity is not a function of a single property but a combination of factors. The mechanism of toxicity was found to be independent of reactive oxygen species formation, as cellular viability could not be rescued in the presence of the antioxidant n-acetyl cysteine. Further exploring these responses at the molecular level, we found that the relatively benign negative QDs increased gene expression of proinflammatory cytokines and those associated with DNA damage, while the highly toxic positive QDs induced changes in genes associated with mitochondrial function. In an attempt to tentatively "rank" the contribution of each property in the observed QD-induced responses, we concluded that QD charge and ligand length, and to a lesser extent, size, are key factors that should be considered when engineering nanomaterials with minimal bioimpact (charge > functionalization > size).

Analysis of quantum dot fluorescence stability in primary blood mononuclear cells

A quantitative assessment of fluorescence signal generation and persistence in blood cells, measured at multiple points over a time course, is presented. Quantum dots (QDs) are inorganic fluorophores that are photostable and nonmetabolized and so can provide quantitative measures of cell biology over multiple cell generations. However, if the potential of these nanoparticles for long-term reporting is to be realized, an understanding of the stability of their fluorescence in living cells is essential. CdTe/ZnS and CdSe/ZnS core/shell dots with peak emission wavelengths of 705 nm and 585 nm, respectively, were loaded, via endocytosis into mononuclear cells extracted from primary blood and flow cytometry used to measure the average fluorescence intensity per cell within populations >10⁴. Time-based study showed a saturation-limited uptake of QDs with a characteristic time of 20 min and a maximum fluorescence signal that is linearly proportional to dot solution concentration. The fluorescence signal decreases after attachment and internalization within cells and is accurately described by a biexponential decay with a rapid initial decay followed by a much slower signal loss with characteristic times of 435 and 7,000 min respectively. Comparison with control samples indicates that interaction with the culture media is a major contributory factor to the initial signal decay. These results provide phenomenological descriptions of the evolving QD fluorescence within live cells with associated analytical equations that allow quantitative assessment of QD-based assays.

Aqueous phase synthesis of CdTe quantum dots for biophotonics

Over the past few years, CdTe quantum dots have been demonstrated as powerful probes for biophotonics applications. The aqueous phase synthesis technique remains the best approach to make high quality CdTe QDs in a single-pot process. CdTe QDs prepared directly in the aqueous phase can have quantum yield as high as 80%. In addition, the surface of CdTe QDs prepared using the aqueous phase technique is functionalized with reactive groups that enable them to be directly conjugated with specific ligands for targeted delivery and sensing. In this contribution, we review recent progress in fabricating aqueous CdTe QDs and exploiting their optical properties in novel approaches to biomedical imaging and sensing applications.

Clinical potential of quantum dots

Advances in nanotechnology have led to the development of novel fluorescent probes called quantum dots. Quantum dots have revolutionalized the processes of tagging molecules within research settings and are improving sentinel lymph node mapping and identification in vivo studies. As the unique physical and chemical properties of these fluorescent probes are being unraveled, new potential methods of early cancer detection, rapid spread and therapeutic management, that is, photodynamic therapy are being explored. Encouraging results of optical and real time identification of sentinel lymph nodes and lymph flow using quantum dots in vivo models are emerging. Quantum dots have also superseded many of the limitations of organic fluorophores and are a promising alternative as a research tool. In this review, we examine the promising clinical potential of quantum dots, their hindrances for clinical use and the current progress in abrogating their inherent toxicity.

Imatinib-loaded polyelectrolyte microcapsules for sustained targeting of BCR-ABL+ leukemia stem cells

Aim: The lack of sensitivity of chronic myeloid leukemia (CML) stem cells to imatinib mesylate (IM) commonly leads to drug dose escalation or early disease relapses when therapy is stopped. Here, we report that packaging of IM into a biodegradable carrier based on polyelectrolyte microcapsules increases drug retention and antitumor activity in CML stem cells, also improving the ex vivo purging of malignant progenitors from patient autografts. Materials & methods: Microparticles/capsules were obtained by layer-by-layer (LbL) self-assembly of oppositely charged polyelectrolyte multilayers on removable calcium carbonate (CaCO3) templates and loaded with or without IM. A leukemic cell line (KU812) and CD34+ cells freshly isolated from healthy donors or CML patients were tested. Results & discussion: Polyelectrolyte microcapsules (PMCs) with an average diameter of 3 µm, fluorescently labelled multilayers sensitive to the action of intracellular proteases and 95–99% encapsulation efficiency of IM, were prepared. Cell uptake efficiency of such biodegradable carriers was quantified in KU812, leukemic and normal CD34+ stem cells (range: 70–85%), and empty PMCs did not impact cell viability. IM-loaded PMCs selectively targeted CML cells, by promoting apoptosis at doses that exert only cytostatic effects by IM alone. More importantly, residual CML cells from patient leukapheresis products were reduced or eliminated more efficiently by using IM-loaded PMCs compared with freely soluble IM, with a purging efficiency of several logs. No adverse effects on normal CD34+ stem-cell survival and their clonogenic potential was noticed in long-term cultures of hematopoietic progenitors in vitro. Conclusion: This pilot study provides the proof-of-principle for the clinical application of biodegradable IM-loaded PMC as feasible, safe and effective ex vivo purging agents to target CML stem cells, in order to improve transplant outcome of resistant/relapsed patients or reduce IM dose escalation.

Células-tronco mononucleares autólogas e proteína óssea morfogenética na cicatrização de defeitos tibiais experimentalmente induzidos em cães

Avaliou-se a utilização de células-tronco mononucleares (CTM) na cicatrização de defeito ósseo experimental como alternativa aos métodos convencionais, analisando-se o tempo de evolução cicatricial e a presença dessas células no tecido neoformado. Foram utilizados 18 cães, separados em três grupos (G) de seis, e de cada animal foram colhidas células da medula óssea (MO), contadas e analisadas para morfometria, por meio da contagem manual e mielograma. Um defeito ósseo tibial foi então criado cirurgicamente, e a lesão tratada com esponja de gelatina embebida em solução fisiológica (G1), esponja de gelatina embebida com aspirado de MO processado (G2) e esponja de gelatina embebida com aspirado de MO processado e proteína óssea morfogenética (rhBMP-2) (G3). A cicatrização foi então avaliada por estudos radiográficos, e a presença de CTM foi identificada por meio de marcadores nanocristais Qtracker, em microscopia com luz fluorescente, uma semana após a intervenção cirúrgica. Entre as células identificadas pelo marcador, foram encontradas células da linhagem óssea. As avaliações radiográficas demonstram crescimento ósseo acelerado nos animais de G2 e G3. Houve diferenças significativas entre o G1 e G3 em todos os tempos estudados, e entre G1 e G2 nos tempos de 30 e 45 dias. A utilização de CTM adultas suplementadas ou não com rhBMP-2 é alternativa favorável ao crescimento ósseo em defeitos experimentais agudos de tíbia de cães.

Synthesis of ternary CuInS(2)/ZnS quantum dot bioconjugates and their applications for targeted cancer bioimaging

This contribution introduces the use of cadmium-free CuInS(2) quantum dots (QDs) for targeted and multiplexed optical imaging of tumors in mice. CuInS(2)/ZnS QDs were synthesized in a non-aqueous phase using the hot colloidal synthesis method. Previous challenges involving stable aqueous dispersion of highly luminescent CuInS(2)/ZnS QDs have been overcome by encapsulating them within functionalized phospholipid micelles, which also facilitated their conjugation with folic acid for targeted delivery. Luminescence signals of QDs of multiple colors were readily differentiated from background autofluorescence in whole animal optical imaging. In addition, two-photon excitation studies revealed that the prepared water-dispersible QDs are suitable for two-photon in vitro and in vivo imaging. This study demonstrates the important key steps in realizing of the potential of CuInS(2) QDs as low-toxicity, photostable, cadmium-free and highly luminescent probes for cancer detection and sensing.

Tracking of human cells in mice

Tracking and tracing of transplanted cells in mice is required in many fields of research. Examples are transplantation of stem cells into organs of mice to study their differentiation capacity and injection of tumor cells to examine metastatic behavior. In the present study we tested the lipid dye CM-DiI and red fluorescent nanoparticles Qdot655 for their applicability in tagging and tracing of human cells in mice. Labeling of different cell types, including MCF-7 human breast cancer cells, human cord blood derived cells, human NeoHep cells and human hepatopancreatic precursor cells, is technically easy and did not compromise further cell culture. After transplantation of CM-DiI or Qdot655 marked cells, red fluorescent structures could be detected already in unprocessed paraffin slices of the studied organs, namely liver, lung, pancreas, kidney, spleen and bone marrow. Next, we examined whether the red fluorescent structures represent the transplanted human cells. For this purpose, we established an in situ hybridization (ISH) technique that allows clear-cut differentiation between human and murine nuclei, based on simultaneous hybridization with human alu and mouse major satellite (mms) probes. We observed a high degree of coincidence between CM-DiI-marked cells and alu positive nuclei. However, also some mms positive cells contained CM-DiI, suggesting phagocytosis of the transplanted CM-DiI-marked cells. The degree of such CM-DiI-positive mouse cells depended on the cell type and route of administration. From a technical point of view it was important that CM-DiI-positive structures in paraffin slices remained fluorescent also after ISH. In contrast, Qdot655 positive structures faded during further staining procedures. In conclusion, marking of cells with CM-DiI or Qdot655 prior to transplantation facilitates recovery of human cells, since a high fraction of positive structures in the host's tissue originate from the transplanted cells. However, CM-DiI or Qdot655 positive staining of individual cells in transplanted tissues is not sufficient to prove their human origin. Additional procedures, such as ISH with alu-probes, are essential, when characterizing individual cells.

Quantum dot-fluorescent protein pairs as novel fluorescence resonance energy transfer probes

Fluorescence resonance energy transfer (FRET) characteristics, including the efficiency, donor-acceptor distance, and binding strength of six fluorescent protein (FP)-quantum dot (QD) pairs were quantified, demonstrating that FPs are efficient acceptors for QD donors with up to 90% quenching of QD fluorescence and that polyhistidine coordination to QD core-shell surface is a straightforward and effective means of conjugating proteins to commercially available QDs. This provides a novel approach to developing QD-based FRET probes for biomedical applications.

Sequestration and homing of bone marrow-derived lineage negative progenitor cells in the lung during pneumococcal pneumonia

Background

Bone marrow (BM)-derived progenitor cells have been shown to have the potential to differentiate into a diversity of cell types involved in tissue repair. The characteristics of these progenitor cells in pneumonia lung is unknown. We have previously shown that Streptococcus pneumoniae induces a strong stimulus for the release of leukocytes from the BM and these leukocytes preferentially sequester in the lung capillaries. Here we report the behavior of BM-derived lineage negative progenitor cells (Lin- PCs) during pneumococcal pneumonia using quantum dots (QDs), nanocrystal fluorescent probes as a cell-tracking technique.

Methods

Whole BM cells or purified Lin- PCs, harvested from C57/BL6 mice, were labeled with QDs and intravenously transfused into pneumonia mice infected by intratracheal instillation of Streptococcus pneumoniae. Saline was instilled for control. The recipients were sacrificed 2 and 24 hours following infusion and QD-positive cells retained in the circulation, BM and lungs were quantified.

Results

Pneumonia prolonged the clearance of Lin- PCs from the circulation compared with control (21.7 ± 2.7% vs. 7.7 ± 0.9%, at 2 hours, P < 0.01), caused preferential sequestration of Lin- PCs in the lung microvessels (43.3 ± 8.6% vs. 11.2 ± 3.9%, at 2 hours, P < 0.05), and homing of these cells to both the lung (15.1 ± 3.6% vs. 2.4 ± 1.2%, at 24 hours, P < 0.05) and BM as compared to control (18.5 ± 0.8% vs. 9.5 ± 0.4%, at 24 hours, P < 0.01). Very few Lin- PCs migrated into air spaces.

Conclusion

In this study, we demonstrated that BM-derived progenitor cells are preferentially sequestered and retained in pneumonic mouse lungs. These cells potentially contribute to the repair of damaged lung tissue.

Receptor-targeted quantum dots: fluorescent probes for brain tumor diagnosis

The intraoperative diagnosis of brain tumors and the timely evaluation of biomarkers that can guide therapy are hindered by the paucity of rapid adjunctive studies. This study evaluates the feasibility and specificity of using quantum dot-labeled antibodies for rapid visualization of epidermal growth factor receptor (EGFR) expression in human brain tumor cells and in surgical frozen section slides of glioma tissue. Streptavidin-coated quantum dots (QDs) were conjugated to anti-EGFR antibodies and incubated with target cultured tumor cells and tissues. The experiments were conducted first in human glioma tumor cell lines with elevated levels of EGFR expression (SKMG-3, U87) and then in frozen tissue sections of glioblastoma multiforme and of oligodendroglioma. The bioconjugated QDs used in the study were found to bind selectively to brain tumor cells expressing EGFR. QD complexed quickly to the cell membrane (less than 15 min), and binding was highly specific and depended on the expression level of EGFR on the cell membrane. Tissue experiments showed that only tumor specimens expressing EGFR were labeled in less than 30 min by QD complexes. These findings demonstrate that QD-labeled antibodies can provide a quick and accurate method for characterizing the presence or absence of a specific predictive biomarker.