Stefanie Heltmann‐Meyer

Friedrich-Alexander-Universität Erlangen-Nürnberg

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Raymund E. Horch

Friedrich-Alexander-Universität Erlangen-Nürnberg

Andreas Arkudas

Friedrich-Alexander-Universität Erlangen-Nürnberg

Dominik Steiner

Friedrich-Alexander-Universität Erlangen-Nürnberg

Dominik Schneidereit

Friedrich-Alexander-Universität Erlangen-Nürnberg

Annika Kengelbach‐Weigand

Friedrich-Alexander-Universität Erlangen-Nürnberg

Oliver Friedrich

Friedrich-Alexander-Universität Erlangen-Nürnberg

Rafael Schmid

Friedrich-Alexander-Universität Erlangen-Nürnberg

Anja-Katrin Boßerhoff

Friedrich-Alexander-Universität Erlangen-Nürnberg

Stefan Schrüfer

Friedrich-Alexander-Universität Erlangen-Nürnberg

Thomas Scheibel

University of Bayreuth

Cooperative Institutions

Friedrich-Alexander-Universität Erlangen-Nürnberg

Universitätsklinikum Erlangen

Bavarian Polymer Institute

University of Würzburg

Universitätsklinikum Würzburg

Creative Commons

University of Bayreuth

Bayer (Germany)

Comprehensive Cancer Center Erlangen

Fraunhofer Institute for Ceramic Technologies and Systems

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Ink comparison for extrusion-based bioprinting in the context of breast cancer and melanoma models

International Journal of Bioprinting (2025)

Stefanie Heltmann‐Meyer Sharly Fleischer Sheetal Kadam Aldo R. Boccaccını Salvador Kirmsse

Biofabrication has proved to be a versatile and valuable tool for tissue engineering and cancer research in order to mimic different tumor microenvironments. In the present study, four different cell lines, including two melanoma cell lines, Mel Im and Mel Wei, and two breast cancer cell lines, MDA-MB-231 and MCF-7, were tested in combination with four hydrogels. The hydrogels were a composite ink consisting of alginate, hyaluronic acid and gelatine (Alg/HA/Gel), pre-crosslinked oxidized alginate with gelatine (ADA-GEL), alginate with methyl cellulose (Meth-Alg) and acrylated hyaluronic acid (HAA). Rheological analysis and shear stress calculations, printability assays and dynamic mechanical analysis were performed on all the hydrogels. The cell lines were then mixed into the hydrogels, printed and examined over a period of 14 days. The focus was on cell survival in the gel, metabolic activity and cell cycle analysis using FUCCI reporters. The results showed that all hydrogels were well printable and Meth-Alg was the softest gel. The cell lines survived the printing process in all inks, but there were significant differences in the metabolic activity and the predominant cell cycle stage. In Alg/HA/Gel, the cells grew in spheroid colonies. ADA-GEL proved to be a good bioink for all cell lines, which enabled proliferation, migration and supported the metabolic activity of the cells, while Meth-Alg offered pores for spreading and proliferating cells. However, it was shown that HAA resulted in the lowest cell number and metabolic activity for all cell lines due to its high polymer content, leading in senescence. Our data demonstrated that depending on the hypothesis, all inks are valuable approaches for breast cancer and melanoma models.

3D bioprinting

10.36922/ijb.5828

Cite

Citations (0)

A New Printable Alginate/Hyaluronic Acid/Gelatin Hydrogel Suitable for Biofabrication of In Vitro and In Vivo Metastatic Melanoma Models

Advanced Functional Materials (2021)

Rafael Schmid Steven K. Schmidt Rainer Detsch Hannes Horder Torsten Blunk

Abstract Two‐dimensional (2D) cancer models have been the standard for drug development over the past few years, but they frequently do not resemble in vivo properties adequately. 3D models are superior in many aspects and are, therefore, more similar to human pathophysiology. Over the past years, the emerging field of biofabrication has made significant advances, resulting in even more sophisticated 3D models. With this study, a hydrogel is created for biofabrication that is suitable for mimicking the tumor microenvironment in vitro and is further tested as a new vascularized melanoma model in vivo. The alginate/hyaluronic acid/gelatin bioink shows good shape‐fidelity, high cell survival rates, and enables successful cultivation of melanoma cells and adipose‐derived stem cells as well as cell differentiation in vitro. In vivo, in the arteriovenous loop model, it proves to be a unique method to study melanoma progression, tumor vascularization, and ultimately and reliably metastases in an isolated and controlled environment. These results show that this 3D model is very application‐oriented for molecular research and therapy development.

Biofabrication

Gelatin

10.1002/adfm.202107993

Cite

Citations (31)

Enhanced vascularization and de novo tissue formation in hydrogels made of engineered RGD-tagged spider silk proteins in the arteriovenous loop model

Biofabrication (2021)

Dominik Steiner Sophie Winkler Stefanie Heltmann‐Meyer Vanessa T. Trossmann Tobias Fey

Abstract Due to its low immunogenic potential and the possibility to fine-tune their properties, materials made of recombinant engineered spider silks are promising candidates for tissue engineering applications. However, vascularization of silk-based scaffolds is one critical step for the generation of bioartificial tissues and consequently for clinical application. To circumvent insufficient vascularization, the surgically induced angiogenesis by means of arteriovenous loops (AVL) represents a highly effective methodology. Here, previously established hydrogels consisting of nano-fibrillary recombinant eADF4(C16) were transferred into Teflon isolation chambers and vascularized in the rat AVL model over 4 weeks. To improve vascularization, also RGD-tagged eADF4(C16) hydrogels were implanted in the AVL model over 2 and 4 weeks. Thereafter, the specimen were explanted and analyzed using histology and microcomputed tomography. We were able to confirm biocompatibility and tissue formation over time. Functionalizing eADF4(C16) with RGD-motifs improved hydrogel stability and enhanced vascularization even outperforming other hydrogels, such as fibrin. This study demonstrates that the scaffold ultrastructure as well as biofunctionalization with RGD-motifs are powerful tools to optimize silk-based biomaterials for tissue engineering applications.

Spider Silk

10.1088/1758-5090/ac0d9b

Cite

Citations (28)

OP6: Gelatin Methacryloyl is a Slow Degrading Material Allowing Vascularization and Long-Term Use In Vivo

Plastic & Reconstructive Surgery Global Open (2022)

Stefanie Heltmann‐Meyer Dominik Steiner Claudia Müller Dominik Schneidereit Oliver Friedrich

INTRODUCTION: Vascularization of bioartificial tissues can be surgically enhanced by means of prefabrication. In this context, the use of arteriovenous loops (AVL) is a powerful tool to enhance vascularization. Besides surgical vascularization, the choice of the appropriate biomaterial has to be considered as an important factor for tissue engineering applications. Therefore, we investigated vascularization and biocompatibility of Gelatin methacryloyl (GelMA) scaffolds in the rat AVL model. MATERIALS AND METHODS: Hydrogels consisting of GelMA (10%) were transferred into an inert chambers and vascularized by AVL in the groin of Lewis rats. After 2 and 4 weeks, the constructs were explanted and further analyzed. Immune response was analyzed based on CD68 and CD163 staining. Vascularization was visualized by α-smooth muscle actin staining and multiphoton microscopy. Moreover, proteome analysis of 53 angiogenesis-related proteins was performed to gain more insight into AVL-induced vascularization. RESULTS: We were able to show that GelMA hydrogels are stable for at least 4 weeks in the rat AVL model. Furthermore, our data indicate that GelMA hydrogels are biocompatible. Finally, we provide evidence that GelMA hydrogels in the AVL model allow connective tissue formation as well as vascularization. In addition, proteomic analysis revealed the upregulation of proangiogenic molecules. CONCLUSION: GelMA has proven to be a stable matrix in the AVL model. Investigations such as multiphoton microscopy and proteome analysis, as well as histological examinations, demonstrated the angiogenic potential of the material in vivo. GelMA is, therefore, a promising material for further applications in vivo.

Gelatin

Biocompatibility

Biomaterial

10.1097/01.gox.0000817668.22449.3c

Cite

Citations (0)

Characterization of two different alginate-based bioinks and the influence of melanoma growth within

Scientific Reports (2024)

Raphael Schipka Stefanie Heltmann‐Meyer Dominik Schneidereit Oliver Friedrich Jonas Röder

Abstract Extrusion-based bioprinting is an established method in biofabrication. Suitable bioinks have fundamentally different compositions and characteristics, which should be examined, in order to find a perfect model system. Here, we investigate the effect of two alginate-based, yet unalike 3D-printed bioinks, pre-crosslinked alginate-dialdehyde gelatin (ADA-GEL) and a mixture of alginate, hyaluronic acid, and gelatin (Alg/HA/Gel), on the melanoma cell line Mel Im and vice versa in terms of stiffness, shrinkage, cellular behavior and colony formation over 15 days. Rheological stiffness measurements revealed two soft gels with similar storage moduli. The cells did not have a significant impact on the overall stiffness, whereas ADA-GEL (2.5/2.5%) was significantly stiffer than Alg/HA/Gel (0.5/0.1/3%). Regarding the shrinkage of printed constructs, cells had a significant influence, especially in ADA-GEL, which has covalent bonds between the oxidized alginate and gelatin. Multi-photon microscopy exhibited proliferation, cell spreading and migration in ADA-GEL with cell–cell and cell–matrix interaction, dissimilarly to Alg/HA/Gel, in which cells formed spherical, encapsulated colonies. Scanning electron microscopy and histology showed degradation and multi-layered growth on ADA-GEL and fewer examples of escaped cells on Alg/HA/Gel. Both gels serve as proliferation bioink for melanoma with more necrosis in deeper Alg/HA/Gel colonies and differences in spreading and matrix interaction. These findings show the importance of proper characterization of the bioinks for different applications.

Gelatin

Biofabrication

Matrix (chemical analysis)

Shrinkage

10.1038/s41598-024-63642-3

Cite

Citations (1)

Highly Cross-Linked Oxidized Alginate-Gelatin (Ada-Gel) Promotes Angiogenesis and Tissue Formation in Vivo in the Arteriovenous Loop Model

Stefanie Heltmann‐Meyer Jonas Hazur Rainer Detsch Lasse Kling Sabrina Pechmann

Reconstruction of large volume defects with autologous tissue may be limited by the associated donor site morbidity. The generation of bioartificial replacement tissues according to the principles of tissue engineering represents a promising possibility for the reduction of donor site morbidity. The vascularization of tissue engineering constructs is an important parameter for successful clinical application. Surgically induced angiogenesis using an arteriovenous (AV) loop can vascularize biomaterials. In addition to vascularization, the material properties of the carrier matrix play an important role. Hydrogels, such as those made from alginate or gelatine, are characterized by good biocompatibility and the possibility of cell encapsulation. They have tuneable properties that can also have an effect on vascularization. This study aims at investigating vascularization and tissue formation of a hydrogel consisting of highly cross-linked alginate dialdehyde (ADA) and gelatin (GEL) in the rat AV loop model. An AV loop was formed between the saphenous vessels using a vein graft. Teflon chambers were filled with ADA-GEL (3.75% – 7.5% w/v) hydrogel containing human transglutaminase (hTG) as an additional enzymatic cross linker and the AV loop was placed in the middle. The Teflon chambers were implanted subcutaneously and the constructs were explanted after 2 and 4 weeks. Afterwards, the parameters biocompatibility, tissue formation and vascularization were analyzed by histology and X-ray microscopy (XRM). After 2 weeks, an initial vascularization of the constructs was already present. Both, de novo tissue formation and vascularization increased after 4 weeks. Besides biodegradation, a good biocompatibility of the ADA-GEL-hTG matrix was observed. Taken together, hydrogels based on ADA-GEL-hTG represent promising scaffold materials for tissue engineering applications.

Gelatin

10.2139/ssrn.4613763

Cite

Citations (0)

A vascularized in vivo melanoma model suitable for metastasis research of different tumor stages using fundamentally different bioinks

Materials Today Bio (2024)

Rafael Schmid Steven K. Schmidt Stefan Schrüfer Dirk W. Schubert Stefanie Heltmann‐Meyer

Although 2D cancer models have been the standard for drug development, they don't resemble in vivo properties adequately. 3D models can potentially overcome this. Bioprinting is a promising technique for more refined models to investigate central processes in tumor development such as proliferation, dormancy or metastasis. We aimed to analyze bioinks, which could mimic these different tumor stages in a cast vascularized arteriovenous loop melanoma model in vivo. It has the advantage to be a closed system with a defined microenvironment, supplied only with one vessel—ideal for metastasis research. Tested bioinks showed significant differences in composition, printability, stiffness and microscopic pore structure, which led to different tumor stages (Matrigel and Alg/HA/Gel for progression, Cellink Bioink for dormancy) and resulted in different primary tumor growth (Matrigel significantly higher than Cellink Bioink). Light-sheet fluorescence microscopy revealed differences in vascularization and hemorrhages with no additional vessels found in Cellink Bioink. Histologically, typical human melanoma with different stages was demonstrated. HMB-45-positive tumors in progression inks were infiltrated by macrophages (CD163), highly proliferative (Ki67) and metastatic (MITF/BRN2, ATX, MMP3). Stainings of lymph nodes revealed metastases even without significant primary tumor growth in Cellink Bioink. This model can be used to study tumor pathology and metastasis of different tumor stages and therapies.

Matrigel

Microphthalmia-associated transcription factor

Primary tumor

Intravasation

10.1016/j.mtbio.2024.101071

Cite

Citations (4)

Vessel grafts for tissue engineering revisited—Vessel segments show location‐specific vascularization patterns in ex vivo ring assay

Microcirculation (2021)

Ravikumar Vaghela Andreas Arkudas Dominik Steiner Stefanie Heltmann‐Meyer Raymund E. Horch

Abstract Objective Transplantation of prefabricated tissue‐engineered flaps can be a potential alternative for healing large tissue defects. Providing adequate vascular supply for an engineered tissue construct is one of the key points in establishing successful tissue engineering‐based treatment approaches. In tissue engineering‐based vascularization techniques like the arteriovenous loop, vascular grafts with high angiogenic potential can help to enhance neovascularization and tissue formation. Therefore, our study aimed to compare the angiogenic potential of vascular grafts from different locations in the rat. Methods The angiogenic activity was investigated by an ex vivo vessel outgrowth ring assay using 1‐mm height vascular segments embedded in fibrin for 2 weeks. Results Maximum vessel outgrowth was observed on Days 10–12. Upper extremity vessels exhibited stronger outgrowth than lower extremity vessels. Moreover, arterial vessels demonstrated higher angiogenic potential compared with venous vessels. Conclusion Collectively, our ex vivo findings suggest that upper extremity arterial vessels have a higher angiogenic capacity, which could be used to improve neovascularization and tissue formation in tissue engineering.

Ex vivo

Vascular tissue

10.1111/micc.12742

Cite

Citations (3)

Recombinant Spider Silk Bioinks for Continuous Protein Release by Encapsulated Producer Cells

Biomacromolecules (2022)

Vanessa T. Trossmann Stefanie Heltmann‐Meyer Hanna Amouei Harald Wajant Raymund E. Horch

Targeted therapies using biopharmaceuticals are of growing clinical importance in disease treatment. Currently, there are several limitations of protein-based therapeutics (biologicals), including suboptimal biodistribution, lack of stability, and systemic side effects. A promising approach to overcoming these limitations could be a therapeutic cell-loaded 3D construct consisting of a suitable matrix component that harbors producer cells continuously secreting the biological of interest. Here, the recombinant spider silk proteins eADF4(C16), eADF4(C16)-RGD, and eADF4(C16)-RGE have been processed together with HEK293 producer cells stably secreting the highly traceable reporter biological TNFR2-Fc-GpL, a fusion protein consisting of the extracellular domain of TNFR2, the Fc domain of human IgG1, and the luciferase of Gaussia princeps as a reporter domain. eADF4(C16) and eADF4(C16)-RGD hydrogels provide structural and mechanical support, promote HEK293 cell growth, and allow fusion protein production by the latter. Bioink-captured HEK293 producer cells continuously release functional TNFR2-Fc-GpL over 14 days. Thus, the combination of biocompatible, printable spider silk bioinks with drug-producing cells is promising for generating implantable 3D constructs for continuous targeted therapy.

Spider Silk

HEK 293 cells

10.1021/acs.biomac.2c00971

Cite

Citations (8)

Gelatin methacryloyl is a slow degrading material allowing vascularization and long-term use in vivo

Biomedical Materials (2021)

Stefanie Heltmann‐Meyer Dominik Steiner Claudia Müller Dominik Schneidereit Oliver Friedrich

Abstract In situ tissue engineering is an emerging field aiming at the generation of ready-to-use three-dimensional tissues. One solution to supply a proper vascularization of larger tissues to provide oxygen and nutrients is the arteriovenous loop (AVL) model. However, for this model, suitable scaffold materials are needed that are biocompatible/non-immunogenic, slowly degradable, and allow vascularization. Here, we investigate the suitability of the known gelatin methacryloyl (GelMA)-based hydrogel for in-situ tissue engineering utilizing the AVL model. Rat AVLs are embedded by two layers of GelMA hydrogel in an inert PTFE chamber and implanted in the groin. Constructs were explanted after 2 or 4 weeks and analyzed. For this purpose, gross morphological, histological, and multiphoton microscopic analysis were performed. Immune response was analyzed based on anti-CD68 and anti-CD163 staining of immune cells. The occurrence of matrix degradation was assayed by anti-MMP3 staining. Vascularization was analyzed by anti- α -smooth muscle actin staining, multiphoton microscopy, as well as expression analysis of 53 angiogenesis-related proteins utilizing a proteome profiler angiogenesis array kit. Here we show that GelMA hydrogels are stable for at least 4 weeks in the rat AVL model. Furthermore, our data indicate that GelMA hydrogels are biocompatible. Finally, we provide evidence that GelMA hydrogels in the AVL model allow connective tissue formation, as well as vascularization, introducing multiphoton microscopy as a new methodology to visualize neovessel formation originating from the AVL. GelMA is a suitable material for in situ and in vivo TE in the AVL model.

Gelatin

10.1088/1748-605x/ac1e9d

Cite

Citations (48)