The emergence of regenerative medicine in organ transplantation: 1st European Cell Therapy and Organ Regeneration Section meeting.

Regenerative medicine is emerging as a novel field in organ transplantation. In September 2019, the European Cell Therapy and Organ Regeneration Section (ECTORS) of the European Society for Organ Transplantation (ESOT) held its first meeting to discuss the state-of-the-art of regenerative medicine in organ transplantation. The present article highlights the key areas of interest and major advances in this multidisciplinary field in organ regeneration and discusses its implications for the future of organ transplantation.

Mesenchymal stromal cells for immunoregulation after liver transplantation: the scene in 2016.

PURPOSE OF REVIEW: The current review presents an update on the existing preclinical and human experience of mesenchymal stromal cell (MSC) therapies for post-transplant immunomodulation. RECENT FINDINGS: Although results from early clinical studies have demonstrated that the application of autologous and allogeneic MSC to be both safe and feasible in a solid organ transplantation setting, for example in liver, the efficacy of MSC immunotherapy demonstrated in preclinical models has yet to be replicated in human clinical trials. SUMMARY: Eagerly awaited results from the second generation of solid organ transplantation clinical trials, many of which are nearing completion, will perhaps establish the effectiveness of combining MSCs and low-dose pharmacological immunosuppression in promoting graft acceptance. At present, the question of whether infusional cell products based on MSCs will have a significant clinical impact in the field of liver transplantation remains open.

Caveats of mesenchymal stem cell therapy in solid organ transplantation.

In the past decade, therapeutic use of mesenchymal stem cells (MSCs) has increased dramatically. The weight of existing evidence supports that the short-term application of MSCs is safe and feasible; however, concerns remain over the possibility of unwanted long-term effects. One fundamental difference between MSCs and pharmacotherapy is that, once applied, the effects of cell products cannot be easily reversed. Therefore, a carefully considered decision process is indispensable before cell infusion. In addition to unwanted interactions of MSCs with the host immune system, there are concerns that MSCs may promote tumor progression or even give rise to cancer themselves. As animal models and first-in-man clinical studies have provided conflicting results, it is challenging to estimate the long-term risk of individual patients. In addition, most animal models, especially rodents, are ill-suited to adequately address questions over long-term side effects. Based on the available evidence, we address the potential pitfalls for the use of MSCs as a therapeutic agent to control alloimmune effects. The aim of this review was not to discourage investigators from clinical studies, but to raise awareness of the intrinsic risks of MSC therapy.

Rationale and prospects of mesenchymal stem cell therapy for liver transplantation.

PURPOSE OF REVIEW: Despite their potential to supplement the donor organ pool, expanded donor criteria grafts are associated with an elevated risk of graft failure and increased early mortality. Likewise, attempts to promote operational graft tolerance through conventional immunosuppressive therapy have demonstrated significant safety-related drawbacks. Because of their potent regenerative and immunomodulative potential, adjunct mesenchymal stem cell (MSC) therapy represents an innovative approach to both of these clinical problems. RECENT FINDINGS: Recent studies have begun to delineate the benefit and mechanisms of short-term therapy combining MSCs and low-dose immunosuppressive drugs in promoting graft acceptance and potentially regeneration. SUMMARY: The current review presents our rationale for the first-in-man clinical trial in liver transplantation utilizing a mesenchymal cell product (MultiStem, Athersys, Cleveland, Ohio, USA). The long-term objective of this program is to safely minimize the dose of complementary immunosuppressive drugs while achieving long-term allograft survival and operational tolerance. The use of adjunct cellular therapy as a means of reducing long-term pharmacotherapy would represent a major advancement in the field of liver transplantation.

Investigating the functional hierarchy of Bacillus megaterium PV361 spore germinant receptors.

Spores of Bacillus megaterium QM B1551 germinate rapidly when exposed to a number of single-trigger germinant compounds, including glucose, proline, leucine, and certain inorganic salts. However, spores of strain PV361, a plasmidless QM B1551 derivative that lacks the GerU germinant receptor (GR) responsible for mediating germination in response to single-trigger compounds, can germinate efficiently when incubated in nutritionally rich media, presumably via activation of additional germinant receptors. In this work, we have identified five chromosomally encoded GRs and attempted to characterize, by mutational analysis, germinant recognition profiles associated with the respective receptors in strain PV361. Of strains engineered with single GR insertion-deletions, only GerK-null spores displayed significant defective germination phenotypes when incubated in 5% (wt/vol) beef extract or plated on rich solid medium. Cumulative decreases in viability were observed in GerK-null spores that also lacked GerA or GerA2, indicating that these GRs, which exerted little effect on spore germination when disrupted individually, have a degree of functionality. Unexpectedly, an efficient germination response to combinations of germinants was restored in GerA(+) spores, which lack all other functional GRs, providing evidence for negative cooperativity between some GRs within the spore. Tetrazolium-based germinative assays conducted with purified spores indicated that these newly characterized B. megaterium GRs are cognate for a wide and chemically diverse range of germinant molecules, but unlike GerU, can only be induced to trigger germination when stimulated by at least two different germinants.

Comparison of two column agglutination tests for red blood cell antibody testing.

BACKGROUND: Several sensitive methods are available for red blood cell (RBC) antibody screening. Among these, gel and glass card systems have demonstrated comparably good performance in retrospective studies and are widely used in routine patient diagnostics, but their performance in prospective studies has not been sufficiently characterised. PATIENTS AND METHODS: Gel card (Bio-Rad DiaMed) and glass bead-based (Ortho Clinical Diagnostics) column agglutination technologies were used to screen for antibodies prospectively (group A) and for antibody identification in stored and fresh samples known to contain RBC antibodies retrospectively (group B). Untreated reagent RBCs and either papain-treated (Bio-Rad) or ficin-treated panel C cells (Ortho) were used for antibody identification. RESULTS: RBC-reactive antibodies were detected in 22 of 1000 group A samples, three of which tested positive only by gel card agglutination, and four only by glass bead agglutination (including one false positive each). Group B comprised 202 sera with known antibodies: 33 of these samples contained 36 antibodies detected only by gel card agglutination, whereas 9 samples contained antibodies detectable only by glass bead-based agglutination. Discrepancies mostly involved weak antibodies reactive by enzyme only. Two sera contained antibody mixtures that neither system detected completely. Of note, in antibody differentiation batches one and two, anti-Lua was reactive in 7 of 7 and 1 of 8 samples, respectively. CONCLUSION: Both column agglutination tests for red cell antibodies had equal sensitivity and specificity with unstored samples. In stored samples, weak and enzyme-only antibodies were more frequently detected with the gel card system.

Proteins YlaJ and YhcN contribute to the efficiency of spore germination in Bacillus subtilis.

The YlaJ and YhcN spore lipoproteins of Bacillus subtilis contain a common domain, and are of unknown function. Homologues of YlaJ or YhcN are widespread in Bacilli and are also encoded in those Clostridia that use cortex lytic enzymes SleB and CwlJ for cortex hydrolysis during germination. In B. subtilis, we report that single and double mutants lacking YlaJ and/or YhcN show a reduced rate of spore germination in L-alanine, with a delay in loss of heat resistance, release of dipicolinic acid and OD fall. If B. subtilis spores lack the cortex lytic enzyme CwlJ, spore cortex degradation and subsequent outgrowth to form colonies is strictly dependent on the other cortex lytic enzyme SleB, allowing a test of SleB function; in a cwlJ mutant background, the combined loss of both ylaJ and yhcN genes resulted in a spore population in which only 20% of spores germinated and outgrew to form colonies, suggesting that SleB activity is compromised. YlaJ and YhcN have a role in germination that is not yet well defined, but these proteins are likely to contribute, directly or indirectly, to early events in germination, including effective SleB function.

Concise Review: Mesenchymal Stromal Cell-Based Approaches for the Treatment of Acute Respiratory Distress and Sepsis Syndromes.

Despite extensive research on candidate pharmacological treatments and a significant and increasing prevalence, sepsis syndrome, and acute respiratory distress syndrome (ARDS) remain areas of unmet clinical need. Preclinical studies examining mesenchymal stromal cell (MSCs) based-therapies have provided compelling evidence of potential benefit; however, the precise mechanism by which MSCs exert a therapeutic influence, and whether MSC application is efficacious in humans, remains unknown. Detailed evaluation of the limited number of human trials so far completed is further hampered as a result of variations in trial design and biomarker selection. This review provides a concise summary of current preclinical and clinical knowledge of MSCs as a cell therapy for sepsis syndrome and ARDS. The challenges of modeling such heterogeneous and rapidly progressive disease states are considered and we discuss how lessons from previous studies of pharmacological treatments for sepsis syndrome and ARDS might be used to inform and refine the design of the next generation of MSC clinical trials. Stem Cells Translational Medicine 2017;6:1141-1151.

First-in-Human Case Study: Multipotent Adult Progenitor Cells for Immunomodulation After Liver Transplantation.

Mesenchymal stem cells and multipotent adult progenitor cells (MAPCs) have been proposed as novel therapeutics for solid organ transplant recipients with the aim of reducing exposure to pharmacological immunosuppression and its side effects. In the present study, we describe the clinical course of the first patient of the phase I, dose-escalation safety and feasibility study, MiSOT-I (Mesenchymal Stem Cells in Solid Organ Transplantation Phase I). After receiving a living-related liver graft, the patient was given one intraportal injection and one intravenous infusion of third-party MAPC in a low-dose pharmacological immunosuppressive background. Cell administration was found to be technically feasible; importantly, we found no evidence of acute toxicity associated with MAPC infusions.

Probing biomolecular interaction forces using an anharmonic acoustic technique for selective detection of bacterial spores.

Receptor-based detection of pathogens often suffers from non-specific interactions, and as most detection techniques cannot distinguish between affinities of interactions, false positive responses remain a plaguing reality. Here, we report an anharmonic acoustic based method of detection that addresses the inherent weakness of current ligand dependant assays. Spores of Bacillus subtilis (Bacillus anthracis simulant) were immobilized on a thickness-shear mode AT-cut quartz crystal functionalized with anti-spore antibody and the sensor was driven by a pure sinusoidal oscillation at increasing amplitude. Biomolecular interaction forces between the coupled spores and the accelerating surface caused a nonlinear modulation of the acoustic response of the crystal. In particular, the deviation in the third harmonic of the transduced electrical response versus oscillation amplitude of the sensor (signal) was found to be significant. Signals from the specifically-bound spores were clearly distinguishable in shape from those of the physisorbed streptavidin-coated polystyrene microbeads. The analytical model presented here enables estimation of the biomolecular interaction forces from the measured response. Thus, probing biomolecular interaction forces using the described technique can quantitatively detect pathogens and distinguish specific from non-specific interactions, with potential applicability to rapid point-of-care detection. This also serves as a potential tool for rapid force-spectroscopy, affinity-based biomolecular screening and mapping of molecular interaction networks.