Frequency and characterization of RHD variant alleles in a population of blood donors from southeastern Brazil: Comparison with other populations.

BACKGROUND: The correct determination of D antigen could help to avoid alloimmunization in pregnant women and patients receiving blood transfusions. However, there are limitations in the identification of D variants as the partial and weak D phenotypes make the determination of D antigen a great challenge in the transfusion routine.' STUDY DESIGN AND METHODS: The molecular characterization of D variants was performed on blood donors from southeastern Brazil with atypical D typing. Furthermore, the serological profile of all RHD variant alleles identified was analyzed using different Anti-D clones. The prevalence of RHD alleles and genotypes found was compared with those described in other countries and in other regions from Brazil. RESULTS: Atypical serologic D typing occurred in 0.79 % of blood donors. The majority of RHD variant alleles (88 %) were first characterized by multiplex PCR and PCR-SSP as RHD*weak partial 4 (47 %), followed by RHD*weak D type 3 (29.9 %), RHD*weak D type 2 (3.9 %) and RHD*weak D type 1 (3.1 %). Genomic DNA sequencing characterized the RHD*weak partial 4 variants found in RHD*DAR1.2 (weak 4.2.2) (22 %), RHD*DAR3 (weak 4.0.1) (2.4 %), RHD*DAR3.1 (weak 4.0) (22 %) and RHD*DAR4 (weak 4.1) (0.8 %). RHD variant alleles associated with partial D, such as, RHD*DAU-4 (1.6 %), RHD*DAU-5 (2.4 %), RHD*DAU-6 (1.6 %), RHD* DIII type 8 (1.6 %), RHD*DVII (3.9 %) and RHD* DMH (0.8 %) were also observed. CONCLUSION: The prevalence of RHD variant alleles observed in this cohort differ from those found in other populations, including Brazilians from other regions. RHD allele distribution in specific regions should be considered for implementation of algorithms and genotyping strategies aiming at a more effective and safe transfusion.

Highly Defined Induced Pluripotent Stem Cell Lines Mimic Donor Red Blood Cell Antigen Profiles for Therapeutic and Diagnostic Use.

Our group generated two induced pluripotent stem cell (iPSC) lines for in vitro red blood cell (RBC) production from blood donors with extensively known erythrocyte antigen profiles. One line was intended to give rise to RBCs for transfusions in patients with sickle cell disease (SCD), while the other was developed to create RBC panel reagents. Two blood donors were selected based on their RBC phenotypes, further complemented by high-throughput DNA array analysis to obtain a more comprehensive erythrocyte antigen profile. Enriched erythroblast populations from the donors' peripheral blood mononuclear cells were reprogrammed into iPSCs using nonintegrative plasmid vectors. The iPSC lines were characterized and subsequently subjected to hematopoietic differentiation. iPSC PB02 and iPSC PB12 demonstrated in vitro and in vivo iPSC features and retained the genotype of each blood donor's RBC antigen profile. Colony-forming cell assays confirmed that iPSC PB02 and iPSC PB12 generated hematopoietic progenitors. These two iPSC lines were generated with defined erythrocyte antigen profiles, self-renewal capacity, and hematopoietic differentiation potential. With improvements in hematopoietic differentiation, these cells could potentially be more efficiently differentiated into RBCs in the future. They could serve as a complementary approach for obtaining donor-independent RBCs and addressing specific demands for blood transfusions.

Ex Vivo Manufacture of Megakaryocytes and Platelets from Stem Cells: Recent Advances Toward Transfusion in Humans.

The generation of ex vivo functional megakaryocytes (MK) and platelets is an important issue in transfusion medicine as donor dependence implies in limitations, such as shortage of eligible volunteers. Indeed, platelet transfusion is still a procedure that saves the lives of patients with defective platelet production. Recent technological development has enabled the isolation and expansion of stem cells that can be used as a source for the production of functional platelets for transfusion. In this review, we discuss recent approaches of in vitro or ex vivo production of MK and platelets, suggesting that, in the near future, donor-independent sources may become a possibility. The feasibility of using these cells in the clinic may be safer, and in vitro manipulation could generate universally compatible products, solving problems related to platelet refractoriness. However, functionality and survival testing of these products in human beings are scarce; therefore, additional studies are needed to consolidate this purpose.

Industrial PE-2 strain of Saccharomyces cerevisiae: from alcoholic fermentation to the production of recombinant proteins.

Saccharomyces cerevisiae is the most important microorganism used in the ethanol fermentation process. The PE-2 strain of this yeast is widely used to produce alcohol in Brazil due to its high fermentation capacity. The aim of the present study was to develop an expression system for recombinant proteins using the industrial PE-2 strain of S. cerevisiae during the alcoholic fermentation process. The protein chosen as a model for this system was CaneCPI-1, a cysteine peptidase inhibitor. A plasmid containing the CaneCPI-1 gene was constructed and yeast cells were transformed with the pYADE4_CaneCPI-1 construct. To evaluate the effect on fermentation ability, the transformed strain was used in the fermentation process with cell recycling. During the nine-hour fermentative cycles the transformed strain did not have its viability and fermentation ability affected. In the last cycle, when the fermentation lasted longer, the protein was expressed probably at the expense of ethanol once the sugars were exhausted. The recombinant protein was expressed in yeast cells, purified and submitted to assays of activity that demonstrated its functionality. Thus, the industrial PE-2 strain of S. cerevisiae can be used as a viable system for protein expression and to produce alcohol simultaneously. The findings of the present study demonstrate the possibility of producing recombinant proteins with biotechnological applications during the ethanol fermentation process.