Bone marrow skeletal stem/progenitor cell defects in dyskeratosis congenita and telomere biology disorders.

Dyskeratosis congenita (DC) is an inherited multisystem disorder, characterized by oral leukoplakia, nail dystrophy, and abnormal skin pigmentation, as well as high rates of bone marrow (BM) failure, solid tumors, and other medical problems such as osteopenia. DC and telomere biology disorders (collectively referred to as TBD here) are caused by germline mutations in telomere biology genes leading to very short telomeres and limited proliferative potential of hematopoietic stem cells. We found that skeletal stem cells (SSCs) within the BM stromal cell population (BMSCs, also known as BM-derived mesenchymal stem cells), may contribute to the hematologic phenotype.

The role of human decay-accelerating factor in the pathogenesis of preterm labor.

Complement activation is thought to contribute to the pathogenesis of preterm labor (PTL). Decay-accelerating factor (DAF) is a natural complement pathway inhibitor. Our hypothesis was that DAF expression on maternal white blood cells (WBCs) in women with preterm labor is elevated compared with women with no preterm labor.

Spontaneous preterm labor is associated with an increase in the proinflammatory signal transducer TLR4 receptor on maternal blood monocytes.

Background: Localized inflammation and increased expression of TLR4 receptors within the uterus has been implicated in the pathogenesis of preterm labor. It remains unclear whether intrauterine inflammatory responses activate the maternal peripheral circulatory system. Therefore we determined whether increased TLR4 expression is present in the peripheral maternal white blood cells of women with spontaneous preterm labor.

Superparamagnetic iron oxide nanoparticles labeling of bone marrow stromal (mesenchymal) cells does not affect their "stemness".

Superparamagnetic iron oxide nanoparticles (SPION) are increasingly used to label human bone marrow stromal cells (BMSCs, also called "mesenchymal stem cells") to monitor their fate by in vivo MRI, and by histology after Prussian blue (PB) staining. SPION-labeling appears to be safe as assessed by in vitro differentiation of BMSCs, however, we chose to resolve the question of the effect of labeling on maintaining the "stemness" of cells within the BMSC population in vivo. Assays performed include colony forming efficiency, CD146 expression, gene expression profiling, and the "gold standard" of evaluating bone and myelosupportive stroma formation in vivo in immuncompromised recipients.

In Vivo Cellular Imaging for Translational Medical Research.

Personalized treatment using stem, modified or genetically engineered, cells is becoming a reality in the field of medicine, in which allogenic or autologous cells can be used for treatment and possibly for early diagnosis of diseases. Hematopoietic, stromal and organ specific stem cells are under evaluation for cell-based therapies for cardiac, neurological, autoimmune and other disorders. Cytotoxic or genetically altered T-cells are under clinical trial for the treatment of hematopoietic or other malignant diseases.

In vivo transfer of intracellular labels from locally implanted bone marrow stromal cells to resident tissue macrophages.

Intracellular labels such as dextran coated superparamagnetic iron oxide nanoparticles (SPION), bromodeoxyuridine (BrdU) or green fluorescent protein (GFP) are frequently used to study the fate of transplanted cells by in vivo magnetic resonance imaging or fluorescent microscopy. Bystander uptake of labeled cells by resident tissue macrophages (TM) can confound the interpretation of the presence of intracellular labels especially during direct implantation of cells, which can result in more than 70% cell death. In this study we determined the percentages of TM that took up SPION, BrdU or GFP from labeled bone marrow stromal cells (BMSCs) that were placed into areas of angiogenesis and inflammation in a mouse model known as Matrigel plaque perfusion assay.

Preterm labor: CD55 in maternal blood leukocytes.

Problem: Intrauterine inflammation is a frequent and significant factor associated with the pathogenesis of preterm labor/birth (PTL/PTB). However, it remains unclear whether the intrauterine inflammatory responses activate the maternal peripheral circulation. We explored the association between PTL/PTB and the 'activation' of the peripheral circulatory system by determining whether CD55 mRNA expression within peripheral WBCs differed between PTL and control patients not in labor.

Detection of migration of locally implanted AC133+ stem cells by cellular magnetic resonance imaging with histological findings.

This study investigated the factors responsible for migration and homing of magnetically labeled AC133(+) cells at the sites of active angiogenesis in tumor. AC133(+) cells labeled with ferumoxide-protamine sulfate were mixed with either rat glioma or human melanoma cells and implanted in flank of nude mice. An MRI of the tumors including surrounding tissues was performed.

In vitro model of bromodeoxyuridine or iron oxide nanoparticle uptake by activated macrophages from labeled stem cells: implications for cellular therapy.

There is increasing interest in using exogenous labels such as bromodeoxyuridine (BrdU) or superparamagnetic iron oxide nanoparticles (SPION) to label cells to identify transplanted cells and monitor their migration by fluorescent microscopy or in vivo magnetic resonance imaging (MRI), respectively. Direct implantation of cells into target tissue can result in >80% cell death due to trauma or apoptosis. Bystander uptake of labeled cells by activated macrophages (AM) can confound the interpretation of results.

Color transformation and fluorescence of Prussian blue-positive cells: implications for histologic verification of cells labeled with superparamagnetic iron oxide nanoparticles.

Superparamagnetic iron oxide (SPIO) nanoparticles, either modified or in combination with other macromolecules, are being used for magnetic labeling of stem cells and other cells to monitor cell trafficking by magnetic resonance imaging (MRI) in experimental models. The correlation of histology to MRI depends on the ability to detect SPIO-labeled cells using Prussian blue (PB) stain and fluorescent tags to cell surface markers. Exposure of PB-positive sections to ultraviolet light at a wavelength of 365 nm commonly used fluorescence microscopy can result in color transformation of PB-positive material from blue to brown.

Expression of transferrin receptor and ferritin following ferumoxides-protamine sulfate labeling of cells: implications for cellular magnetic resonance imaging.

Ferumoxides-protamine sulfate (FE-Pro) complexes are used for intracellular magnetic labeling of cells to non-invasively monitor cell trafficking by in vivo MRI. FE-Pro labeling is non-toxic to cells; however, the effects of FE-Pro labeling on cellular expression of transferrin receptor (TfR-1) and ferritin, proteins involved in iron transport and storage, has not been reported. FE-Pro-labeled human mesenchymal stem cells (MSCs), HeLa cells and primary macrophages were cultured from 1 week to 2 months and evaluated for TfR-1 and ferritin gene expression by RT-PCR and protein levels were determined using Western blots.

Structure-function analysis of decay-accelerating factor: identification of residues important for binding of the Escherichia coli Dr adhesin and complement regulation.

Decay-accelerating factor (DAF), a complement regulatory protein, also serves as a receptor for Dr adhesin-bearing Escherichia coli. The repeat three of DAF was shown to be important in Dr adhesin binding and complement regulation. However, Dr adhesins do not bind to red blood cells with the rare polymorphism of DAF, designated Dr(a(-)); these cells contain a point mutation (Ser165-Leu) in DAF repeat three.