Cryopreserved human heart valve allografts: a ten-year single centre experience.

This study provides an overview of tissue banking activities at the Croatian Cardiovascular Tissue Bank (CTB) during past ten years and presents the outcomes of cryopreserved heart valve allografts (CHAs) use in different patient groups. From June 2011 until December 2021, 75 heart donations were referred to CTB: 41 recipient of heart transplant (RHT), 32 donors after brain death (DBD) and 2 donors after circulatory death (DCD) donations. Processing resulted in 103 valves of which 65 met quality requirements for clinical use. Overall tissue discard rate was 37%. The most frequent reasons for discard were inadequate morphology (12%) in RHT donations and microbiological contamination (19%) in DBD donations. Altogether, 38 CHAs were transplanted to 36 patients. Recipients were divided in three groups; infective endocarditis (IE), non-infectious heart disease and congenital heart disease group. In the IE group, the 30-day, 1-year and 3-year survival was 71%, 53% and 47%, respectively. Freedom from re-operation due to all graft-related causes was 76% and due to structural valve deterioration 88%. There were no cases of graft reinfection. In the congenital heart disease group CHAs were predominantly (94%) used for right ventricular outflow tract reconstruction and 88% of patients recovered without graft-related complications. At present, the number of demands for CHAs at CTB considerably outweighs their availability.

Comparative Analysis of Biological and Functional Properties of Bone Marrow Mesenchymal Stromal Cells Expanded in Media with Different Platelet Lysate Content.

Due to their ability to induce immunological tolerance in the recipient, mesenchymal stromal cells (MSCs) have been utilized in the treatment of various hematological and immune- and inflammation-mediated diseases. The clinical application of MSCs implies prior in vitro expansion that usually includes the use of fetal bovine serum (FBS). The present study evaluated the effect of different platelet lysate (PL) media content on the biological properties of MSCs. MSCs were isolated from the bone marrow of 13 healthy individuals and subsequently expanded in three different culture conditions (10% PL, 5% PL, 10% FBS) during 4 passages. The cells cultured in different conditions had comparable immunophenotype, clonogenic potential, and differentiation capacity. However, MSC growth was significantly enhanced in the presence of PL. Cultures supplemented with 10% PL had a higher number of cumulative population doublings in all passages when compared to the 5% PL condition (p < 0.03). Such a difference was also observed when 10% PL and 10% FBS conditions were compared (p < 0.005). A statistically significant difference in population doubling time was determined only between the 10% PL and 10% FBS conditions (p < 0.005). Furthermore, MSCs cultured in 10% PL were able to cause a 66.9% reduction of mitogen-induced lymphocyte proliferation. Three chromosome aberrations were detected in PL conditions. Since two changes occurred in the same do nor, it is possible they were donor dependent rather than caused by the culture condition. These findings demonstrate that a 10% PL condition enables a higher yield of MSCs within a shorter time without altering MSC properties, and should be favored over the 5% PL condition.

Mesenchymal stromal cells from pooled mononuclear cells of multiple bone marrow donors as rescue therapy in pediatric severe steroid-refractory graft-versus-host disease: a multicenter survey.

To circumvent donor-to-donor heterogeneity which may lead to inconsistent results after treatment of acute graft-versus-host disease with mesenchymal stromal cells generated from single donors we developed a novel approach by generating these cells from pooled bone marrow mononuclear cells of 8 healthy "3(rd)-party" donors. Generated cells were frozen in 209 vials and designated as mesenchymal stromal cell bank. These vials served as a source for generation of clinical grade mesenchymal stromal cell end-products, which exhibited typical mesenchymal stromal cell phenotype, trilineage differentiation potential and at later passages expressed replicative senescence-related markers (p21 and p16). Genetic analysis demonstrated their genomic stability (normal karyotype and a diploid pattern). Importantly, clinical end-products exerted a significantly higher allosuppressive potential than the mean allosuppressive potential of mesenchymal stromal cells generated from the same donors individually. Administration of 81 mesenchymal stromal cell end-products to 26 patients with severe steroid-resistant acute graft-versus-host disease in 7 stem cell transplant centers who were refractory to many lines of treatment, induced a 77% overall response at the primary end point (day 28). Remarkably, although the cohort of patients was highly challenging (96% grade III/IV and only 4% grade II graft-versus-host disease), after treatment with mesenchymal stromal cell end-products the overall survival rate at two years follow up was 71±11% for the entire patient cohort, compared to 51.4±9.0% in graft-versus-host disease clinical studies, in which mesenchymal stromal cells were derived from single donors. Mesenchymal stromal cell end-products may, therefore, provide a novel therapeutic tool for the effective treatment of severe acute graft-versus-host disease.

[Mesenchymal stem cells: immunomodulatory properties and clinical application]. / Mezenhimske maticne stanice: imunomodulatorne znacajke i klinicka primjena.

Mesenchymal stem cells (MSCs) are multipotent nonhematopoietic cells that were first identified in bone marrow. Clinical interest for MSCs was initiated by the observation that MSCs are immunoprivileged cells that display immunomodulatory properties in vitro. Ex vivo expanded MSCs have therefore become a new type of cellular therapy in development with a wide range of potential clinical applications. So far many clinical studies confirmed safety of their use and showed that infused MSCs suppress graft versus host disease, support engraftment of transplanted allogeneic hematopoietic stem cells and stimulate growth in patients with osteogenesis imperfecta. Although underlying immunomodulatory mechanisms of action are not completely understood, potential benefit of MSC therapy justifies its clinical use in a broad range of disorders. In this report we give historical overview of MSC discovery and current scientific and clinical achievements in this field. Better insight into their biological properties and mechanisms of action are needed.

[The diversity of extended gene haplotypes HLA-B*27 in Croatia]. / Raznovrsnost produzenih haplotipova gena HLA-B*27 u Hrvatskoj.

In the present study the extended haplotypes of HLA-B*27 gene were analysed in the sample of 42 Croatian families. Peripheral blood (2 ml) was collected from all the individuals and genomic DNA was extracted using a commercial kit. The HLA alleles were determined using the method PCR sequence specific primers (PCR-SSP) while the microsatellite alleles were amplified using the method PCR-STR. Analysis of HLA-A-B*27-D6S2927-STR MICA-TNFalpha-DRB1 extended haplotypes demonstrated the strongest linkage disequilibrium between HLA-B*27 alleles and microsatellite alleles D6S2927-1 and STR_MICA-A4. Analysis indicated that the rare allele B*2730 is always present in the extended haplotype HLA-A3-B*2730-D6S2927-1-STR MICA-A4-TNFalpha-9-DRB1*16. The results of the present study will be applied in future studies of association between microsatellite alleles and spondyloarthropathies and contribute to a better understanding of peptide binding to HLA class I molecules, as well as other aspects of immune response.