The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact.

This work aims towards the development of a modular system for fabrication of monodisperse microgels made of poly(2-oxazoline)s for use in the field of regenerative therapy.

The melanoma cell adhesion molecule defines mesenchymal stromal cells in the human bone marrow that regenerate bone and establish a hematopoietic microenvironment in vivo. The role of the melanoma cell adhesion molecule in primary human mesenchymal stromal cells and the maintenance of hematopoietic stem and progenitor cells during ex vivo culture has not yet been demonstrated. We applied RNA interference or ectopic overexpression of the melanoma cell adhesion molecule in human mesenchymal stromal cells to evaluate the effect of the melanoma cell adhesion molecule on their proliferation and differentiation as well as its influence on co-cultivated hematopoietic stem and progenitor cells. Knockdown and overexpression of the melanoma cell adhesion molecule affected several characteristics of human mesenchymal stromal cells related to osteogenic differentiation, proliferation, and migration. Furthermore, knockdown of the melanoma cell adhesion molecule in human mesenchymal stromal cells stimulated the proliferation of hematopoietic stem and progenitor cells, and strongly reduced the formation of long-term culture-initiating cells. In contrast, melanoma cell adhesion molecule-overexpressing human mesenchymal stromal cells provided a supportive microenvironment for hematopoietic stem and progenitor cells. Expression of the melanoma cell adhesion molecule increased the adhesion of hematopoietic stem and progenitor cells to human mesenchymal stromal cells and their migration beneath the monolayer of human mesenchymal stromal cells. Our results demonstrate that the expression of the melanoma cell adhesion molecule in human mesenchymal stromal cells determines their fate and regulates the maintenance of hematopoietic stem and progenitor cells through direct cell-cell contact.

Heparan sulfate Proteoglycans (HSPG) are ubiquitous molecules with indispensable functions in various biological processes. Glypicans are a family of HSPG’s, characterized by a Gpi-anchor which directs them to the cell surface and/or extracellular matrix where they regulate growth factor signaling during development and disease. We report the identification and expression pattern of glypican genes from zebrafish. The zebrafish genome contains 10 glypican homologs, as opposed to six in mammals, which are highly conserved and are phylogenetically related to the mammalian genes. Some of the fish glypicans like Gpc1a, Gpc3, Gpc4, Gpc6a and Gpc6b show conserved synteny with their mammalian cognate genes. Many glypicans are expressed during the gastrulation stage, but their expression becomes more tissue specific and defined during somitogenesis stages, particularly in the developing central nervous system. Existence of multiple glypican orthologs in fish with diverse expression pattern suggests highly specialized and/or redundant function of these genes during embryonic development.

Heparan sulfate Proteoglycans (HSPG) are ubiquitous molecules with indispensable functions in various biological processes. Glypicans are a family of HSPG’s, characterized by a Gpi-anchor which directs them to the cell surface and/or extracellular matrix where they regulate growth factor signaling during development and disease. We report the identification and expression pattern of glypican genes from zebrafish. The zebrafish genome contains 10 glypican homologs, as opposed to six in mammals, which are highly conserved and are phylogenetically related to the mammalian genes. Some of the fish glypicans like Gpc1a, Gpc3, Gpc4, Gpc6a and Gpc6b show conserved synteny with their mammalian cognate genes. Many glypicans are expressed during the gastrulation stage, but their expression becomes more tissue specific and defined during somitogenesis stages, particularly in the developing central nervous system. Existence of multiple glypican orthologs in fish with diverse expression pattern suggests highly specialized and/or redundant function of these genes during embryonic development.

This work aims towards the development of a modular system for fabrication of monodisperse microgels made of poly(2-oxazoline)s for use in the field of regenerative therapy.

Von regenerativen Zellen freigesetzte vesikuläre Strukturen mit einer Lipiddoppelmembran, sogenannte extrazelluläre Vesikel (EVs), stellen einen vielversprechenden Ansatz dar zukünftig Herz-Kreislauf-Erkrankungen zu behandeln. In diesem Zusammenhang untersuchte die vorliegende Arbeit die Eignung von EVs allogener humaner Herzzellen (CardAP-Zellen) als mögliches Therapeutikum für Erkrankungen des Herzens. Zu diesem Zwecke wurden die EVs durch differentielle Zentrifugation aus dem konditionierten Medium von CardAP-Zellen nach Kultivierung mit oder ohne pro-inflammatorische Zytokine gewonnen. Die so isolierten EV- Präparationen beider Konditionen zeigten vergleichbare Konzentrationen und verfügten sowohl über charakteristische vesikuläre Strukturen als auch transportierte Moleküle, wie die Tetraspanine. Allerdings wiesen stimulierte EVs im Gegensatz zur nichtstimulierten Vergleichsgruppe ein größeres Repertoire an miRNAs und kleinere Durchmesser auf. In verschiedenen in vitro Analysen konnte zudem nachgewiesen werden, dass EVs von CardAP-Zellen i) die Angiogenese fördern, ii) die Apoptose von Herzzellen vermindern, iii) nur schwach immunogen sind und iv) induzierte Immunreaktionen verringern können. Dabei wurden teils deutliche Unterschiede zwischen den induzierten Effekten von EVs aus stimulierten und nichtstimulierten Konditionen dokumentiert, die darauf schließen lassen, dass verschiedene Mechanismen in der Empfängerzelle angeregt werden durch die Interaktion mit den jeweiligen EVs. Insbesondere konnte in der vorliegenden Arbeit gezeigt werden, dass CD14+ Immunzellen eine essentielle Rolle bei der immunmodulierenden Wirkung der EVs in induzierten Immunreaktionen besitzen. Zusammenfassend stellen EVs von allogenen CardAP-Zellen ein aussichtsreiches therapeutisches Werkzeug für Herz-Erkrankungen dar und zukünftige Studien werden klären, ob eine Anwendung im Menschen möglich ist. / From cells released vesicular structures with a lipid bilayer, the so-called extracellular vesicles (EVs), cannot reproduce but can affect important processes in a recipient cell. EVs of regenerative cells represent a promising therapeutic approach. In this context, the present work investigated whether heart diseases could be treated in the future by using EVs from allogeneic regenerative human cardiac cells (CardAP cells). For this purpose, EVs were isolated by differential centrifugation from the conditioned medium of CardAP cells cultured with or without pro-inflammatory cytokines. These obtained EV preparations from both EV biogenesis conditions exhibited comparable concentrations, characteristic vesicular structures, and characteristic transported molecules, such as the tetraspanins. However, stimulated EVs showed a larger repertoire of miRNAs and smaller diameters in contrast to their unstimulated counterpart. Most importantly, different in vitro analysis demonstrated that the isolated EVs from CardAP cells i) promote angiogenesis, ii) decrease cardiac cell apoptosis, iii) have a low immunogenicity, and iv) can reduce induced immune responses. Interestingly, differences were documented in these beneficial features between stimulated and unstimulated EV preparations, suggesting that different mechanisms in the recipient cell are stimulated by the interaction with the respective EVs. Moreover, CD14+ cells (mainly monocytes) were shown to play an essential role in the detected immunomodulation of EVs. In summary, EVs from CardAP cells appear to be a promising therapeutic tool for cardiac diseases and further studies will clarify open questions such as the efficacy in the organism.