Graft-versus-host disease and treatment with mesenchymal stromal cells

Graft-versus-host disease of both the acute (aGvHD) and chronic (cGvHD) variety remains a major cause of mortality and morbidity after allogeneic hematopoietic stem cell transplantation (HSCT). During the last 15 years, mesenchymal stromal cells (MSC) have been explored as a promising new treatment for aGvHD, but there are many questions to be answered in this young field. The aim of this thesis is to expand our understanding of MSC treatment and GvHD with a specific focus on safety, factors affecting the outcome of MSC therapy and the possibility of treating also cGvHD with MSC. In paper I we performed a long-term follow up study of the first patients treated with MSC, and reported on their outcome. We demonstrated a high frequency of infections and recommend the use of prophylactic drugs and close surveillance of patients during and following MSC treatment. Regarding factors affecting the outcome, we reported an association between low passage MSC and better clinical outcome, indicating that MSC lose some of their potency with extensive culturing. In paper II, we analysed autopsy reports and tissue samples from patients treated with MSC and could demonstrate that MSC do not appear to engraft in the patients. The risk of malignant transformation of donated MSC should therefore be very low. In paper III we demonstrated a correlation between vitamin D deficiency prior to HSCT and an increased incidence of cGvHD, indicating vitamin D deficiency as a possible risk factor for cGvHD. Paper IV reports on a clinical trial of MSC therapy in refractory cGvHD. Eleven patients were included; of whom nine received up to six repeated infusions of MSC and could be evaluated for response. Of these nine, six patients responded to MSC therapy with durable improvement in cGvHD symptoms and could significantly reduce systemic immunosuppression. To summarize, this thesis provides new data regarding the safety of MSC therapy and suggests that the use of MSC is relatively safe, provided that necessary precautions are taken regarding infectious complications. With this information at hand, we could move forward to expanding the use of MSC in conditions with less dire expectations than refractory aGvHD, such as cGvHD. The clinical study of MSC therapy in cGvHD is one of the largest reported worldwide and suggests that repeated infusions of MSC could be a valuable treatment option for these patients

Mesenchymal Stromal Cells Engage Complement and Complement Receptor Bearing Innate Effector Cells to Modulate Immune Responses

Infusion of human third-party mesenchymal stromal cells (MSCs) appears to be a promising therapy for acute graft-versus-host disease (aGvHD). To date, little is known about how MSCs interact with the body's innate immune system after clinical infusion. This study shows, that exposure of MSCs to blood type ABO-matched human blood activates the complement system, which triggers complement-mediated lymphoid and myeloid effector cell activation in blood. We found deposition of complement component C3-derived fragments iC3b and C3dg on MSCs and fluid-phase generation of the chemotactic anaphylatoxins C3a and C5a. MSCs bound low amounts of immunoglobulins and lacked expression of complement regulatory proteins MCP (CD46) and DAF (CD55), but were protected from complement lysis via expression of protectin (CD59). Cell-surface-opsonization and anaphylatoxin-formation triggered complement receptor 3 (CD11b/CD18)-mediated effector cell activation in blood. The complement-activating properties of individual MSCs were furthermore correlated with their potency to inhibit PBMC-proliferation in vitro, and both effector cell activation and the immunosuppressive effect could be blocked either by using complement inhibitor Compstatin or by depletion of CD14/CD11b-high myeloid effector cells from mixed lymphocyte reactions. Our study demonstrates for the first time a major role of the complement system in governing the immunomodulatory activity of MSCs and elucidates how complement activation mediates the interaction with other immune cells

Återvinning av fosfor från avloppsvatten och slam till produkter : slutrapport

The Swedish project P-to-Product focused on developing and adapting methods to promote recirculation of phosphorus (P) products extracted from sewage and sewage sludge. The project consisted of three work packages: 1) market introduction, 2) environmental impacts and 3) agricultural requirements. In wp 1 opportunities and barriers were identified and policy recommendations developed. This was done through interviews, surveys and workshops with stakeholders from sewage utilities, innovation companies, the fertilizer industry, the federation of Swedish farmers and national authorities. In wp 2 a simplified Life Cycle Assessment (LCA) was developed focused on nutrient recycling, global warming potential and energy use. In addition to this a chemical checkpoint was formulated with chemical analysis of a wide range of pollutants. For the development of methods in wp 2, granulated or pelleted nutrient products from the companies EkoBalans (a struvite based product with nitrogen and potassium added) and Outotec (a P-product with origin from incinerated sewage sludge) were used as case products. These products were also used in wp 3 where physical properties were evaluated and spreading tests were executed using existing machinery. The project provided a useful set of methods which soon will be complemented with methods to assess plant nutrient efficiency

Do ABO Blood Group Antigens Hamper the Therapeutic Efficacy of Mesenchymal Stromal Cells?

Investigation into predictors for treatment outcome is essential to improve the clinical efficacy of therapeutic multipotent mesenchymal stromal cells (MSCs). We therefore studied the possible harmful impact of immunogenic ABO blood groups antigens - genetically governed antigenic determinants - at all given steps of MSC-therapy, from cell isolation and preparation for clinical use, to final recipient outcome. We found that clinical MSCs do not inherently express or upregulate ABO blood group antigens after inflammatory challenge or in vitro differentiation. Although antigen adsorption from standard culture supplements was minimal, MSCs adsorbed small quantities of ABO antigen from fresh human AB plasma (ABP), dependent on antigen concentration and adsorption time. Compared to cells washed in non-immunogenic human serum albumin (HSA), MSCs washed with ABP elicited stronger blood responses after exposure to blood from healthy O donors in vitro, containing high titers of ABO antibodies. Clinical evaluation of hematopoietic stem cell transplant (HSCT) recipients found only very low titers of anti-A/B agglutination in these strongly immunocompromised patients at the time of MSC treatment. Patient analysis revealed a trend for lower clinical response in blood group O recipients treated with ABP-exposed MSC products, but not with HSA-exposed products. We conclude, that clinical grade MSCs are ABO-neutral, but the ABP used for washing and infusion of MSCs can contaminate the cells with immunogenic ABO substance and should therefore be substituted by non-immunogenic HSA, particularly when cells are given to immunocompentent individuals

Do ABO Blood Group Antigens Hamper the Therapeutic Efficacy of Mesenchymal Stromal Cells?

Investigation into predictors for treatment outcome is essential to improve the clinical efficacy of therapeutic multipotent mesenchymal stromal cells (MSCs). We therefore studied the possible harmful impact of immunogenic ABO blood groups antigens - genetically governed antigenic determinants - at all given steps of MSC-therapy, from cell isolation and preparation for clinical use, to final recipient outcome. We found that clinical MSCs do not inherently express or upregulate ABO blood group antigens after inflammatory challenge or in vitro differentiation. Although antigen adsorption from standard culture supplements was minimal, MSCs adsorbed small quantities of ABO antigen from fresh human AB plasma (ABP), dependent on antigen concentration and adsorption time. Compared to cells washed in non-immunogenic human serum albumin (HSA), MSCs washed with ABP elicited stronger blood responses after exposure to blood from healthy O donors in vitro, containing high titers of ABO antibodies. Clinical evaluation of hematopoietic stem cell transplant (HSCT) recipients found only very low titers of anti-A/B agglutination in these strongly immunocompromised patients at the time of MSC treatment. Patient analysis revealed a trend for lower clinical response in blood group O recipients treated with ABP-exposed MSC products, but not with HSA-exposed products. We conclude, that clinical grade MSCs are ABO-neutral, but the ABP used for washing and infusion of MSCs can contaminate the cells with immunogenic ABO substance and should therefore be substituted by non-immunogenic HSA, particularly when cells are given to immunocompentent individuals

Evaluation ABO-related clinical response to MSCs.

<p>Patient characteristics and evaluation of clinical response to individual MSC-infusions in patients undergoing HSCT (Stockholm, n = 70; and Leiden, n = 35 MSC infusions). Blood type O (containing highest titers of both anti-A/B antibodies) was compared to blood type A, B, and AB (blood containing anti-B, anti-A, or no anti-A/B antibodies, respectively). Abbreviations: HSCT, hematopoietic stem cell transplantation; MSC, mesenchymal stromal cell; BG, blood group; HLA, human leukocyte antigen. Statistics: P-value is calculated using Mann-Whitney rank-sum test (for continuous variables), Fisher’s exact t-test (comparing two categorical variables), or Chi²-test (comparing more than two categorical variables).</p