Lydia Lammers

Publications of Lydia Lammers

• Impact of DAG stimulation on mineral synthesis, mineral structure and osteogenic differentiation of human cord blood stem cells.

  Authors: Lydia Lammers, Christian Naujoks, Karin Berr, Rita Depprich, Norbert Kübler, Ulrich Meyer, Fabian Langenbach, Beate Lüttenberg, Gesine Kögler, Hans-Peter Wiesmann, Jörg Handschel

  Stem cell research. 03/2012; 8(2):193-205.

  It remains unexplored in what way osteogenic stimulation with dexamethasone, ascorbic acid and β-glycerol phosphate (DAG) influences the process of mineralization, the composition and structure ofIt remains unexplored in what way osteogenic stimulation with dexamethasone, ascorbic acid and β-glycerol phosphate (DAG) influences the process of mineralization, the composition and structure of the assembled mineral. Therefore, we analyzed and characterized biomineralization in DAG-stimulated and unstimulated 3D human unrestricted somatic stem cell (USSC) cultures. Microspheres were analyzed by histological staining, scanning electron microscopy (SEM), semi-quantitative energy-dispersive X-ray spectroscopy (EDX), quantitative wavelength-dispersive X-ray spectroscopy (WDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Raman spectroscopy. Mineral material was detected by SEM and histological staining in both groups, and showed structural differences. DAG influenced the differentiation of USSCs and the formation, structure and composition of the assembled mineral. SEM showed that cells of the +DAG spheres exhibited morphological signs of osteoblast-like cells. EDX and WDX confirmed a Ca-P mineral in both groups. Overall, the mineral material found showed structural similarities to the mineral substance of bony material.

• Embryonic stem cells in scaffold-free three-dimensional cell culture: osteogenic differentiation and bone generation.

  Authors: Jörg Handschel, Christian Naujoks, Rita Depprich, Lydia Lammers, Norbert Kübler, Ulrich Meyer, Hans-Peter Wiesmann

  Head & face medicine. 01/2011; 7:12.

  Extracorporeal formation of mineralized bone-like tissue is still an unsolved challenge in tissue engineering. Embryonic stem cells may open up new therapeutic options for the future and should be anExtracorporeal formation of mineralized bone-like tissue is still an unsolved challenge in tissue engineering. Embryonic stem cells may open up new therapeutic options for the future and should be an interesting model for the analysis of fetal organogenesis. Here we describe a technique for culturing embryonic stem cells (ESCs) in the absence of artificial scaffolds which generated mineralized miromasses. Embryonic stem cells were harvested and osteogenic differentiation was stimulated by the addition of dexamethasone, ascorbic acid, and ß-glycerolphosphate (DAG). After three days of cultivation microspheres were formed. These spherical three-dimensional cell units showed a peripheral zone consisting of densely packed cell layers surrounded by minerals that were embedded in the extracellular matrix. Alizarine red staining confirmed evidence of mineralization after 10 days of DAG stimulation in the stimulated but not in the control group. Transmission electron microscopy demonstrated scorching crystallites and collagenous fibrils as early indication of bone formation. These extracellular structures resembled hydroxyl apatite-like crystals as demonstrated by distinct diffraction patterns using electron diffraction analysis. The micromass culture technique is an appropriate model to form three-dimensional bone-like micro-units without the need for an underlying scaffold. Further studies will have to show whether the technique is applicable also to pluripotent stem cells of different origin.

• Compatibility of Embryonic Stem Cells with Biomaterials.

  Authors: Jorg Handschel, Karin Berr, Rita Depprich, Christian Naujoks, Norbert R Kubler, Ulrich Meyer, Michelle Ommerborn, Lydia Lammers

  Journal of biomaterials applications. 09/2008;

  Periodontal bone defects and atrophy of the jaws in an aging population are of special concern. Tissue engineering using embryonic stem cells (ESCs) and biomaterials may offer new therapeuticPeriodontal bone defects and atrophy of the jaws in an aging population are of special concern. Tissue engineering using embryonic stem cells (ESCs) and biomaterials may offer new therapeutic options. The purpose of this study is to evaluate the compatibility of ESCs with biomaterials and the influence of biomaterials on the osteogenic gene expression profile.Therefore, ESCs are cultured with various biomaterials. The cytocompatibility of murine ESCs is measured regarding the proliferation of the cells on the materials by CyQUANT(R) assay, the morphology by scanning electron microscopy, and the influence on the gene expression by real time PCR.The results show that insoluble collagenous bone matrix, followed by beta-tricalciumphosphate, is most suitable for bone tissue engineering regarding cell proliferation, and phenotype. The gene expression analysis indicates that biomaterials do influence the gene expression of ESCs.Our results provide new insight into the cytocompatibility of ESCs on different scaffolds.

• Osseointegration of zirconia implants: an SEM observation of the bone-implant interface.

  Authors: Rita Depprich, Holger Zipprich, Michelle Ommerborn, Eduardo Mahn, Lydia Lammers, Jörg Handschel, Christian Naujoks, Hans-Peter Wiesmann, Norbert R Kübler, Ulrich Meyer

  Head & face medicine. 02/2008; 4:25.

  BACKGROUND: The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics,BACKGROUND: The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. METHODS: A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. RESULTS: Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. CONCLUSION: The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.