Silk-Based Bone Marrow "Factories" Move Lab-Grown Platelets Closer to Clinical Use
核心洞察
EU-funded researchers are using silk fibroin (搜索), a protein derived from silkworms, to build bioreactors that mimic bone marrow and produce platelets outside the human body.
The technology addresses a critical supply bottleneck, as donor platelets can be preserved for only about five days and require room-temperature storage.
A silk-based bioink now enables 3D-printing of bone marrow models that reduce cellular stress and DNA damage, improving drug testing and disease research.
EU-funded researchers are using silk fibroin (搜索), a protein derived from silkworm cocoons, to build artificial bone marrow "factories" capable of producing platelets outside the human body. The work, led by Professor Alessandra Balduini, a haematologist and researcher in the Department of Molecular Medicine at the University of Pavia, Italy, and Dr Hana Raslova, research director at the Gustave Roussy Institute (搜索) near Paris, aims to ease medicine's dependence on limited and fragile donor blood supplies.
Platelets are tiny, disk-shaped cell fragments that help blood clot and stop bleeding, and they are used routinely in hospitals, particularly for cancer patients undergoing chemotherapy, which can sharply reduce the body's natural platelet production. Yet they are among medicine's most fragile blood products. Unlike red blood cells, which can be stored for several weeks, platelets last just a few days and must be kept at room temperature, increasing the risk of contamination and complicating storage and transport.
"The bottleneck for platelets is that they can be preserved just for five days," Balduini explained. Supply can also fluctuate significantly throughout the year, with donation rates often falling during summer holidays and major disruptions such as pandemics quickly straining national blood systems. According to the World Health Organization, around 118 million blood donations are collected globally every year, but platelet supplies remain difficult to maintain because the products expire so quickly. Adding to the complexity, around 15% of platelet transfusions require specially matched tissue types, making shortages even harder to manage.
"We produce platelets in the lab to overcome this limitation and face the growing demand," said Balduini.
Recreating bone marrow in the lab
Inside the human body, platelets are produced in the bone marrow by large cells called megakaryocytes, which release platelets into the bloodstream in response to highly specific biological and mechanical signals. Replicating that process outside the body has proved remarkably difficult. "Many labs are trying to develop platelets for transfusion purposes, but it's not so easy," said Raslova.
One of the biggest challenges is reproducing the complex structure of bone marrow itself, which contains several specialised microenvironments, or "niches," that help regulate how blood cells grow and develop. To recreate those conditions, researchers turned to silk fibroin (搜索), a natural fibre harvested from the cocoons of domesticated silkworms that is strong, flexible and biocompatible.
"Silk is one of the few materials that can be used for bone marrow and platelets," Balduini explained. "You want a material that can support the process without affecting the functionality, and silk can do this."
Building a platelet factory
As part of the EU-funded SilkFUSION initiative, which ran from 2017 to 2022, Balduini and her colleagues developed a silk-based bioreactor designed to mimic the environment inside human bone marrow. In the follow-up SilkPlatelet initiative, which ended in December 2025, researchers pushed the concept further, using stem cells to generate megakaryocytes inside the silk bioreactor system and working to improve the efficiency of platelet production, including through the use of genetically modified stem cells.
"The process is quite expensive, but we are using the genetically modified stem cells to produce more platelets from fewer cells, so by improving platelet production we optimised the price of the whole technology," explained Raslova.
Although the work remains experimental, the researchers say the technology is steadily moving closer to clinical reality. The bone marrow bioreactor is already being tested by pharmaceutical companies and research groups interested in future medical applications.
Looking beyond transfusions
The work has also opened up broader possibilities beyond platelet transfusions alone. In the SILKink initiative, which ran until May 2026, the researchers developed a silk-based "bio-ink" that can be used to 3D-print highly accurate models of bone marrow tissue in different shapes and sizes. These printed tissues could help scientists study blood diseases, test new drugs and better understand how stem cells behave in different biological environments.
The bioink addresses a key limitation of earlier models, which lacked the softness necessary to closely mimic bone marrow tissue. If bone marrow structure is not well represented, cells introduced to it can become stressed and damaged, resulting in changes to their DNA that mask the effect of drugs being tested in the model. "Since we are mimicking the bone marrow, the cells are in a physiological-like state, so they have less DNA damage, they have less stress, less inflammation. So you can study the impact of a drug in a real system," Balduini explained.
Another major outcome of the project was the launch of a start-up, Silk4B (搜索), to commercialise the team's advanced 3D bone marrow models and related silk-based products. "We give the possibility to researchers to use bone marrow models they can really trust for their experiments," noted Balduini. The start-up is selling the products to researchers, pharmaceutical companies and academics worldwide.
The long-term ambition behind these three interconnected projects is significant: to move platelet supply away from a system heavily dependent on donors and vulnerable to shortages towards one capable of producing platelets reliably on demand. For that to happen, today's experimental systems will need to grow into a large-scale, clinically ready production line.
Although it will likely be several years before these lab-derived platelets reach transfusion clinics, researchers are optimistic. "We are confident that in the near future, it will be possible to produce platelets for a range of clinical applications," said Raslova.
Before that happens, the researchers must demonstrate that laboratory-grown platelets are safe, effective and scalable enough for routine clinical use. Small animal tests have been successfully conducted and clinical application is the next step. "We still have to understand the proof of principle and scale up to clinical application, but EU funding has been critical in helping us move forward," said Balduini.