Morg1(+/-) heterozygous mice are protected from experimentally induced focal cerebral ischemia.

Focal cerebral ischemia (stroke) and reperfusion injury leads to acute and chronic brain damage. The increase of the hypoxia-inducible transcription factor alpha (HIF-α), an important transcription factor for several genes, may attenuate ischemic brain injury. We recently identified a new WD-repeat protein designated Morg1 (MAPK organizer 1) that interacts with prolyl hydroxylase 3 (PHD3), an important enzyme involved in the regulation of HIF-1α and HIF-2α expression. While homozygous Morg1(-/-) mice are embryonically lethal, heterozygous Morg1(+/-) mice have a normal phenotype. Brain vasculature as well as systolic blood pressure in Morg1(+/-) mice were indistinguishable from wild-type (WT) animals. We show here that Morg1(+/-) mice were partially protected from cerebral ischemia/reperfusion injury in comparison to WT (Morg1(+/+)) animals using the middle cerebral artery occlusion model (MCAO). Morg1(+/-) mice compared with WT animals revealed a significantly reduced infarct volume as detected by Nissl and Map 2 staining despite a similar restriction of blood flow in both mice genotypes as measured by laser Doppler flowmetry. Immunohistochemistry revealed specific Morg1 expression in reactive astrocytes in the ipsilateral (ischemic) hemisphere in Morg1(+/-) and WT mice, especially in the penumbral regions. In the contralateral hemisphere, Morg1 was not detectable. Furthermore, Morg1 mRNA expression was significantly enhanced in the ischemic brain of WT, but not in ischemic brain tissue obtained from Morg1(+/-) animals. However, HIF-1α was expressed with the same intensity in Morg1(+/-) and WT mice with no difference between the ipsilateral and contralateral hemispheres. No positive staining for HIF-2α was found in ischemic (ipsilateral) and non-ischemic (contralateral) brain regions in Morg1(+/+) and Morg1(+/-) mice. Almost no PHD3 staining was found in the contralateral hemispheres of either WT or heterozygous Morg1(+/-) mice. Transcript expression for the HIF1α-dependent genes erythropoietin (Epo) and vascular endothelial growth factor 164 (VEGF 164) were significantly reduced in the ischemic brain from Morg1(+/-) mice. Positive staining for PHD3 in the ipsilateral hemisphere of WT mice was suggested to occur in astrocytes. A compensatory increase in Morg1 expression in astrocytes in the penumbra may negatively influence infarct volume. It appears that these effects are independent of the PHD3-HIF1α axis.

Regional differences in HLA antigen and haplotype frequency distributions in Germany and their relevance to the optimization of hematopoietic stem cell donor recruitment.

We analyzed regional differences in human leukocyte antigen (HLA)-A, -B, and -DR antigen and haplotype frequencies based on a sample of approximately 320,000 German donors in order to identify regions that are especially suited for ongoing stem cell donor recruitment. Geographic partitioning was carried out by postal code regions. Analysis of genetic distances suggests the existence of three regional clusters in South (regions 6-9), East (0-1), and Northwest (2-5) Germany. The southern cluster shows most favorable characteristics with respect to haplotypic and phenotypic diversity and the occurrence of rare HLA antigens. The opposite behavior is shown by regions 2-4 of the northwestern cluster. As a result of lower HLA diversity, completeness of a regional donor file in region 4 with 100,000 donors would be higher than that of a file in region 7 with 170,000 donors. This fact shows the relevance of regional HLA differences for practical donor registry planning. Results such as those presented in this work can be used to diminish the problem of decreasing marginal benefit of donor recruitment, as more than 13 million donors are registered worldwide today.

Criteria for initiation and evaluation of minority donor programs and application to the example of donors of Turkish descent in Germany.

Minority donor programs aim to improve access to unrelated hematopoietic SCT for specific ethnic groups through directed donor recruitment. We have developed criteria for initiation and evaluation of such programs and applied them to the situation of donors of Turkish descent in Germany, as well as a program by DKMS German Bone Marrow Center that targets this group. Criteria for program initiation include the number of accessible minority donors, potential impact on the chances of finding matching donors, and general access to unrelated transplantation for patients of the targeted group. Success criteria comprise number and availability of recruited donors, the effect of these donors on the HLA phenotype distribution of a donor file, and the number of donations resulting from the program. More than 40 000 donors of Turkish descent have been recruited within the analyzed program to date. Recruited minority donors show more favorable demographic characteristics but lower availability rates than do German donors. Although HLA haplotype distributions of Turkish and German donors differ considerably, patients with common Turkish HLA phenotypes should benefit from the German donor pool even without a specific minority program. The analysis of donations from minority donors, however, shows specific benefits for patients with rare HLA phenotypes.

Selective recruitment of stem cell donors with rare human leukocyte antigen phenotypes.

Many patients in need of a hematopoietic stem cell transplant do not find a fully matching donor although more than 11,000,000 potential donors are registered worldwide. Therefore, it is relevant to recruit donors who add diversity to the donor pool. We present the 'Roots' approach that includes the selection of already registered donors with rare HLA phenotypes and the recruitment of relatives of these donors. Two projects (Roots A and B) with different donor selection criteria were carried out. HLA phenotype frequency distributions of new donors differ significantly from the respective control groups: 2.7% of Roots A donors versus 1.1% of the control group have an HLA-AB phenotype that is unique in the DKMS file (P=0.001). Additionally, 39.5% of Roots B donors but only 18.3% of the control group have a unique HLA-ABDR phenotype (P<0.001). Similar results are found when phenotypes that are at most available 10 times in the DKMS donor file are analyzed. The results show that the Roots approach is generally suited to increasing the ratio of donors with rare HLA phenotypes in a donor file. Additional costs of Roots donor recruitment seem justified through the ratio of recruited donors with rare HLA phenotypes.

Approaches to managing volunteer marrow donor registry HLA data. Algorithms for directing donor center-initiated HLA-DR typing of selected donors.

The German bone marrow donor center (DKMS) hasrecruited over 732 500 donors during the first 9 years of its existence. Initially, donors were typed for HLA-A and B, and DR typing was only done on request for a patient-initiated search. In 1994, a project was started which led to the donor center-initiated DR typing (DCI-DRT) of >35,000 donors. These donors were selected by donor-specific criteria (age, sex, height and weight) and according to HLA-A and B phenotypes. The latter was done to avoid unnecessary DR typing of the most common A, B phenotypes With a follow up of >6 years, this strategy has led to a number of confirmatory typings (CT) (n=4588) and stem cell harvests (n=568), which is at least comparable to those ensuing after patient-initiated HLA-DR typing (126 000 DR typings, 8,213 CTs, 888 resulting in stem-cell donation). DCI-DRT seems to be a cost-effective strategy which may help to reduce search times and improve search outcome, and improve the overall efficiency of donor center operations