Biosilk 521
Biosilk 521
Biosilk 521 is a recombinant 3D culture matrix biofunctionalized with Biolaminin 521 to create stem cell relevant niches for pluripotent (PSC) and adult stem cell organoids.
Biosilk 521 is a recombinant 3D culture matrix biofunctionalized with Biolaminin 521 to support integration, survival, long-term growth, and differentiation of human pluripotent stem cells (hPSCs), mesenchymal stromal cells (MSCs), and adult stem cells. The fibrous architecture of Biosilk permits free diffusion of oxygen and nutrients while Biolaminin 521 guarantees optimal attachment, high survival rates, and sustained self-renewal of stem cell in vitro.
Section of a Biosilk 521 network showing self-organized neural-tube-like structures after 60 days of 3D culture. SOX2 (red) proliferative zones form around ventricular-like regions, surrounded by βIII-tubulin (green) neurons, indicating organized neuroepithelial patterning [Åstrand et al., 2020].
A defined and long-term 3D organoid culture
Our 3D solution provides the structural and diffusional benefits of a Biosilk microfiber network while providing defined 3D microenvironment with Biolaminin 521 that closely replicates the naïve hPSC niche. Together, these features support consistent hPSC expansion, reduce intra-culture variation and support physiologically relevant cell–matrix and cell–cell interactions to establish long-term differentiation protocols. Biosilk 521 is a robust tool for disease modelling, drug discovery, regenerative medicine and advanced cell-therapy applications.
Key benefits of Biosilk 521
Biorelevant 3D microenvironment
Combining Biosilk with Biolaminin 521 creates a defined network that closely mimics the natural stem cell niche, supporting optimal attachment, survival, and lineage-specific differentiation.
Long-term culture support
The microfiber network enables efficient nutrient and oxygen diffusion, allowing long-term stability and maturation of organoids without compromising cell viability.
Defined and animal-origin free
Chemically defined, recombinant, biodegradable, and non-immunogenic, Biosilk 521 is animal-origin free, providing a consistent matrix for research and translational applications
Reduced variability
Biosilk 521 promotes uniform cell integration and organization, reducing batch-to-batch and intra-organoid variation compared with conventional organoid systems
No necrotic cores
Enhanced diffusion and 3D architecture prevent formation of necrotic centers, even in large organoids, supporting healthier, fully functional tissue models.
Versatile and easy to use
Biosilk forms 3D microfiber networks without special equipment and, combined with LN521, creates customized micro-environments for most proliferating cell types e.g. stem cells, and enables long-term differentiation with multiple protocols available.
Recommended applications
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Pluripotent stem cells
Biorelevant culture of human ES and iPS cells on Biolaminin substrates Biolaminin 521 successfully replicates the genuine human stem cell niche in […] -
Neural cells
Biorelevant culture of neural cells on Biolaminin substrates Laminins are widely expressed in the nervous system and are essential for the developme […] -
Skin cells
Biorelevant culture of keratinocytes on Biolaminin substrates The basement membrane composition in the epidermis Human epidermal keratinocyte (HEK) […] -
Intestinal cells
Biorelevant culture of intestinal cells on Biolaminin substrates Laminin expression in the intestine The small intestine contains mucosal epithelia […] -
Hepatocytes and hepatoblasts
Biorelevant culture of liver cells on Biolaminin substrates Several laminins play a vital role in liver progenitor cell-mediated regeneration The li […] -
Eye cells
Biorelevant culture of eye cells on full-length laminin-521 Laminin proteins are integral components in the eye microenvironment Biolaminin products […]
Key features
The microfiber architecture of Biosilk combined with Biolaminin allows oxygen, nutrients, and patterning factors to freely diffuse throughout the 3D network. Unlike encapsulated systems, cells are directly integrated into the microfibers, enabling even cell integration, high proliferation, and long-term differentiation protocols. This supports the generation of larger organoids with uniform cellular specialization and organization, without the risk of necrotic cores.
Biosilk and Biolaminin are chemically defined, animal-origin-free matrices, ensuring consistent performance and eliminating variability associated with animal-derived substrates. This defined composition enables reproducible cell expansion, differentiation, and organoid formation, providing a reliable platform for both basic research and translational studies where experimental standardization are crucial.
Biosilk biofunctionalized with Biolaminin mimics the native extracellular matrix, creating a tissue-like microenvironment. This enhances integrin-mediated attachment, promotes physiological cell morphology, and increases experimental and preclinical relevance.
The combination of Biosilk and Biolaminin is fully biocompatible and non-immunogenic and has been shown to support vascularization and tissue remodeling in preclinical models. Its non-immunogenic properties further make it a safe platform for translational applications.
The functional and mechanical properties of Biosilk combined with Biolaminin allow for integration, expansion, and long-term differentiation of a wide range of cell types, including hPSCs, MSCs, and neural, pancreatic, and skin progenitors. By selecting the appropriate tissue-specific Biolaminin isoform for each application (e.g. LN521 for hPSCs culture), the network can be tailored to provide an optimal microenvironment, making it a versatile platform for disease modeling, drug discovery, and translational medicine.
Biosilk with Biolaminin provides a biologically relevant 3D microfiber network that mimics the native cellular niche and extracellular matrix, where cells attach to fibers, elongate, and establish defined focal adhesion points. The mild assembly process enables immediate and even integration of cells, promoting physiologically relevant cell–cell contacts and network formation, which enhances self-organization and morphogenesis. These interactions are critical for accurate modeling of in vivo cell behavior in long-term cultures.
A 3D microfiber network to support PSCs in culture
hiPSCs (DAPI) integrate into the microfiber Biosilk 521 network and are stained for pluripotency markers NANOG and OCT4 after 72 h in culture. Biolaminin 521 (LN521)-coated fibers are shown in green [Åstrand et al., 2020].
Tissue-specific organoids on Biosilk 521
hiPSC-derived cardiomyocyte progenitors are cultured in the Biosilk 521 microfiber network [unpublished].
hPSC-derived neural constructs in a Biosilk 521 network after 40 days of 3D culture show MAP2⁺ neurons (green), SOX2⁺ (red) progenitor zones, and KI67⁺ proliferative cells in vertical and horizontal sections, illustrating organized neuroepithelial architecture, uniform cell integration, and long-term viability [Åstrand et al., 2020].
No necrotic core after 6 month of culture, enabling clearer dopaminergic neuron development
Over extended culture periods, the silk microfiber network prevents necrotic core formation, supports sustained cell survival, and enables progressive maturation and diversification of dopaminergic neurons in midbrain organoids on Biosilk 111 [Fiorenzano et al., 2021].
Lowest inter- and intra- organoid variability in Biosilk 111 ventral midbrain organoids
Biosilk + LN111 (Biosilk 111) organoids show more uniform cell clustering and a higher proportion of dopaminergic neurons compared with conventional (Matrigel) ventral midbrain organoids at one month [Fiorenzano et al., 2021].
Variety of cells cultured on Biosilk
Biosilk and niche-specific Biolaminin microfiber networks can be used to grow a wide variety of primary cells and cell lines. Numerous publications demonstrate their versatility across different cell types and applications. For guidance and technical support. We are happy to provide publications and advice to help you get the most out of your 3D cultures.
Protocol overview: Create attached or free-floating Biosilk+Biolaminin microfiber networks
A 3D foam structure can easily be generated by the gentle introduction of air bubbles into the Biosilk solution. The cell suspension is mixed into the foam, and the silk with cells assembles into a thin film around each bubble. The bubbles disperse and the foam transforms into a stabilized 3D network with uniformly integrated cells between the microfibers.
Pipetting introduces air bubbles to form dense foams with cells which disperse over the course of 3 days
A 3D foam structure can be generated by a gentle introduction of air bubbles into the Biosilk solution. The cell suspension is mixed into the foam, and the silk with cells assembles into a thin film around each bubble. The bubbles disperse and the foam transforms into a stabilized 3D network with uniformly integrated cells between the microfibers.
Simple to use – no special equipment needed
Product name
Biosilk 521
Product code
BS521-0101
Declaration
For research use or non-commercial manufacturing of cell, gene, or tissue-based products
Storage
-80°C
Stock concentration
3 mg/ml total
9 µg/ml Biolaminin 521
Appearance
Clear, colorless
Shipping condition
Dry Ice
Stability
24 months
Product description
Recombinant spider silk protein, functionalized with human recombinant laminin 521 protein (Biolaminin 521) for 3D culture applications
Classification
Defined and animal origin-free, human recombinant protein
Product application
Human PSC and progenitor cell expansion and differentiation
Assembly of FN-silk with laminin-521 to integrate hPSCs into a three-dimensional culture for neural differentiation
Åstrand C , Chotteau V , Falk A , Hedhammar M
Biomaterials science, 2020
Assembly of functionalized silk together with cells to obtain proliferative 3D cultures integrated in a network of ECM-like microfibers
Johansson U, Widhe M, Shalaly ND, Arregui IL, Nilebäck L, Tasiopoulos CP, Åstrand C, Berggren PO, Gasser C, Hedhammar M.
Scientific reports, 2019
Fiorenzano A, Sozzi E, Birtele M, Kajtez J, Giacomoni J, Nilsson F, Andreas Bruzelius A, Sharma Y, Zhang Y, Mattsson B, Emnéus J, Rylander Ottosson D, Storm P, Parmar M
Nature Communications, 2021
Silk networking drives self-assembly of functional and mature human brain organoids
Sozzi E, Kajtez J, Bruzelius A, Wesseler MF, Nilsson F, Birtele M, Larsen NB, Rylander Ottosson D, Storm P, Parmar M, Fiorenzano A
Front. Cell Dev. Biol., 2022
Silk-Ovarioids: establishment and characterization of a human ovarian primary cell 3D-model system | Human Reproduction Open | Oxford Academic
Di Nisio V , Li T, Xiao Z, Papaikonomou K, Damdimopoulos A, Végvári A, Lebre F, Alfaro-Moreno E, Pedersen M, Svingen T, Zubarev R, Acharya G, Damdimopoulou P, Salumets A
Human Reproduction Open, 2025
Astrid Källén A, Taebnia N, Widhe M, Lauschke V.M, Hedhammar M
Biotechnology and Bioengineering, 2025
Biological responses to spider silk-antibiotic fusion protein
Gomes S, Gallego-Llamas J, Leonor IB, Mano JF, Reis RL, Kaplan DL.
J Tissue Eng Regen Med, 2017