Selection of hematopoietic stem cells with a combination of galactose-bound vinyl polymer and soybean agglutinin, a galactose-specific lectin

Practicability of prenatal testing using lectin-based enrichment of fetal erythroblasts

AIM

The aim of this study was to investigate the practicability and efficiency of lectin-based isolation of fetal erythroblasts for clinical use in non-invasive prenatal testing.

METHODS

Peripheral blood samples were collected from 39 pregnant women. Leukocytes were removed with an anti-CD45 antibody after density gradient centrifugation. After blood cells were attached to slides by binding to a galactose-specific lectin and galactose-bound vinyl polymer, the slides were stained with May-Grünwald-Giemsa stain and cells were classified by automated image analysis based on their size and the nuclear area/cytoplasmic area ratio. In 14 samples from the women with male fetuses, fetal origin of the isolated erythroblasts was confirmed by detecting the Y chromosome using fluorescence in situ hybridization. In eight samples, single erythroblasts were collected by the laser capture microdissection technique for amplification of the sex-determining region Y gene to confirm fetal origin.

RESULTS

Panning with an anti-CD45 antibody achieved stable removal of leukocytes without aggregation. In all samples, erythroblasts were successfully identified by automated image analysis (18-6000/10 mL of blood). The number of slides required to examine 10 mL of blood ranged from one to six, which was reasonable for clinical use. The Y chromosome was detected in 7.5-43.6% of erythroblasts by fluorescence in situ hybridization, and the sex-determining region Y gene was amplified in seven of eight samples.

CONCLUSION

The combination of lectin-based erythroblast isolation and automated image analysis is a practical and efficient method for isolating fetal erythroblasts as a source of fetal genomes.

Selective Expansion of CD34+ Cells from Mouse Bone Marrow Cultured on LH/P MP-Coated Plates with Adequate Cytokines

Low-molecular-weight heparin/protamine microparticles (LH/P MPs) serve as carriers for controlled release of heparin-binding cytokines. LH/P MPs were stably coated onto plastic surfaces by drying. The purpose of this study is to evaluate a culture method for selective expansion of CD34+ cells using LH/P MPs as cytokine-binding matrix. Ficoll-purified mouse bone marrow cells (mouse FP-BMCs) containing CD34+ cells were cultured on LH/P MP-coated plates in the presence of stem cell factor (SCF), thrombopoietin (Tpo), and Flt-3 ligand (Flt-3) in hematopoietic progenitor growth medium (HPGM) supplemented with 4% heat-inactivated fetal bovine serum (FBS). After 8 days of culture, the total cell count increased 4.6-fold, and flow cytometry analyses revealed that 23.8% of the initial cells and 57.4% of the expanded cells were CD34 positive. Therefore, CD34+ cells were estimated to have increased 11.0-fold. In contrast, cultured CD34+ cells on uncoated tissue culture plates increased 5.8-fold in an identical medium.

High-yield expression of recombinant soybean agglutinin in plants using transient and stable systems

Soybean agglutinin (SBA) is a specific N-acetylgalactosamine-binding plant lectin that can agglutinate a wide variety of cells. SBA has great potential for medical and biotechnology-focused applications, including screening and treatment of breast cancer, isolation of fetal cells from maternal blood for genetic screening, the possibility as a carrier system for oral drug delivery, and utilization as an affinity tag for high-quality purification of tagged proteins. The success of these applications, to a large degree, critically depends on the development of a highly efficient expression system for a source of recombinant SBA (rSBA). Here, we demonstrate the utility of transient and stable expression systems in Nicotiana benthamiana and potato, respectively, for the production of rSBA, with the transgenic protein accumulated to 4% of total soluble protein (TSP) in Nicotiana benthamiana leaves and 0.3% of TSP in potato tubers. Furthermore, we show that both plant-derived rSBAs retain their ability to induce the agglutination of red blood cells, are similarly glycosylated when compared with native SBA, retained their binding specificity for N-acetylgalactosamine, and were highly resistant to degradation in simulated gastric and intestinal fluids. Affinity column purification using N-acetylgalactosamine as a specific ligand resulted in high recovery and purity of rSBA. This work is the first step toward use of rSBA for various new applications, including the development of rSBA as a novel affinity tag for simplified purification of tagged proteins and as a new carrier molecule for delivery of oral drugs.

In vitro protection of umbilical cord blood-derived primitive hematopoietic stem progenitor cell pool by mannose-specific lectins via antioxidant mechanisms

BACKGROUND

Earlier we reported that an oral administration of two mannose-specific dietary lectins, banana lectin (BL) and garlic lectin (GL), led to an enhancement of hematopoietic stem and progenitor cell (HSPC) pool in mice.

STUDY DESIGN AND METHODS

Cord blood-derived CD34+ HSPCs were incubated with BL, GL, Dolichos lectin (DL), or artocarpin lectin (AL) for various time periods in a serum- and growth factor-free medium and were subjected to various functional assays. Reactive oxygen species (ROS) levels were detected by using DCHFDA method. Cell fractionation was carried out using lectin-coupled paramagnetic beads.

RESULTS

CD34+ cells incubated with the lectins for 10 days gave rise to a significantly higher number of colonies compared to the controls, indicating that all four lectins possessed the capacity to protect HSPCs in vitro. Comparative analyses showed that the protective ability of BL and GL was better than AL and DL and, therefore, further experiments were carried out with them. The output of long-term culture-initiating cell (LTC-IC) and extended LTC-IC assays indicated that both BL and GL protected primitive stem cells up to 30 days. The cells incubated with BL or GL showed a substantial reduction in the ROS levels, indicating that these lectins protect the HSPCs via antioxidant mechanisms. The mononuclear cell fraction isolated by lectin-coupled beads got enriched for primitive HSPCs, as reflected in the output of phenotypic and functional assays.

CONCLUSION

The data show that both BL and GL protect the primitive HSPCs in vitro and may also serve as cost-effective HSPC enrichment tools.