TY - BOOK

T1 - Multifunktionale nanostrukturierte Hydrogele zur Kultur hämatopoetischer Stammzellen

AU - Ludwig-Husemann, Anita

N1 - Doctoral thesis

PY - 2023

Y1 - 2023

N2 - To understand the functional interactions of hematopoietic stem and progenitor cells (HSPCs) with their physiological niche in bone marrow, artificial niche models are excellent for studying individual biochemical and biophysical niche properties. In this work, a two-dimensional, nanostructured, heparin-based biohybrid hydrogel was developed to mimic multiple functions for in vitro HSPC culture. Three essential functionalities of the niche were in the focus of this study: (i) matrix elasticity, (ii) cytokine binding and release, and (iii) nanostructured presentation of extracellular or cellular α4β1 integrin peptide ligands. With unchanged matrix elasticity within physiological bone marrow stiffness, different densities of cellular IDSP or extracellular LDV as integrin α4β1-specific binding motifs were realized by varying the nanostructure. In addition, the gel matrix was able to specifically bind and release the chemokine SDF-1α. The influence of the multifunctional gel properties on human CD34+ HSPCs was investigated in terms of cell polarization, cell motility, proliferation and degree of differentiation. The following cell behavior was observed in this work. The degree of polarization and motility of HSPC cultures showed a clear dependence on ligand type, but were independent of ligand density. SDF-1α promotively affected cell polarization but not cell motility. Proliferation of total HSPCs and expansion of CD34+ cells both showed no dependence on nanostructuring. SDF-1α had only a small reducing effect on differentiation. The nanostructured presentation of IDSP revealed a pronounced negative correlation between the degree of differentiation and nanoparticle spacing, which determines IDSP ligand density. The results show a clear interplay between HSPCs and the biohybrid hydrogel system studied here. The different effects of the cellular and extracellular integrin binding motif can be primarily explained by the different binding affinity of the activated α4β1 integrin for the different ligands. For differentiation affected by IDSP ligand density, it remains unclear whether, for a given matrix elasticity, more efficient α4β1 integrin activation occurs at high or low ligand densities. Finally, a synergetic cooperative effect between simultaneously activated α4β1 integrin and SDF-1α receptor on HSPCs on cell polarization was detected for both integrin ligands. In contrast, the resulting effect of SDF-1α in combination with the IDSP ligand on differentiation appears to be antagonistic in nature. Thus, the results based on nanostructured integrin ligands contribute to a better understanding of the complex interplay of HSPCs with their bone marrow niche. By enabling simultaneous tailoring of multiple niche factors in such biohybrid hydrogel systems, the behavior of HSPCs ex vivo could be more specifically studied and influenced in the future.

AB - To understand the functional interactions of hematopoietic stem and progenitor cells (HSPCs) with their physiological niche in bone marrow, artificial niche models are excellent for studying individual biochemical and biophysical niche properties. In this work, a two-dimensional, nanostructured, heparin-based biohybrid hydrogel was developed to mimic multiple functions for in vitro HSPC culture. Three essential functionalities of the niche were in the focus of this study: (i) matrix elasticity, (ii) cytokine binding and release, and (iii) nanostructured presentation of extracellular or cellular α4β1 integrin peptide ligands. With unchanged matrix elasticity within physiological bone marrow stiffness, different densities of cellular IDSP or extracellular LDV as integrin α4β1-specific binding motifs were realized by varying the nanostructure. In addition, the gel matrix was able to specifically bind and release the chemokine SDF-1α. The influence of the multifunctional gel properties on human CD34+ HSPCs was investigated in terms of cell polarization, cell motility, proliferation and degree of differentiation. The following cell behavior was observed in this work. The degree of polarization and motility of HSPC cultures showed a clear dependence on ligand type, but were independent of ligand density. SDF-1α promotively affected cell polarization but not cell motility. Proliferation of total HSPCs and expansion of CD34+ cells both showed no dependence on nanostructuring. SDF-1α had only a small reducing effect on differentiation. The nanostructured presentation of IDSP revealed a pronounced negative correlation between the degree of differentiation and nanoparticle spacing, which determines IDSP ligand density. The results show a clear interplay between HSPCs and the biohybrid hydrogel system studied here. The different effects of the cellular and extracellular integrin binding motif can be primarily explained by the different binding affinity of the activated α4β1 integrin for the different ligands. For differentiation affected by IDSP ligand density, it remains unclear whether, for a given matrix elasticity, more efficient α4β1 integrin activation occurs at high or low ligand densities. Finally, a synergetic cooperative effect between simultaneously activated α4β1 integrin and SDF-1α receptor on HSPCs on cell polarization was detected for both integrin ligands. In contrast, the resulting effect of SDF-1α in combination with the IDSP ligand on differentiation appears to be antagonistic in nature. Thus, the results based on nanostructured integrin ligands contribute to a better understanding of the complex interplay of HSPCs with their bone marrow niche. By enabling simultaneous tailoring of multiple niche factors in such biohybrid hydrogel systems, the behavior of HSPCs ex vivo could be more specifically studied and influenced in the future.

U2 - 10.15488/13328

DO - 10.15488/13328

M3 - Doctoral thesis

CY - Hannover

ER -