Investigating The Formulation of Caf1 Based Materials as Polymeric Inks for Bioprinting

Background and context

Osteoarthritis (OA) is a painful and progressive joint disease affecting over 10 million people in the UK, yet the development of new treatments is limited by a lack of reliable, cost‑effective models that accurately replicate human joint tissue.

As populations age, OA prevalence is expected to rise significantly, placing increasing pressure on healthcare systems.

About the Project

To address this challenge, MarraBio, CPI and the Henry Royce Institute collaborated to develop next-generation 3D printable biomaterials that better mimic the complex structure of joint tissue, for the ultimate purpose of creating more accurate models of osteochondral (OC) tissue, the interface between cartilage and bone that is particularly affected in OA.

Central to the project were MarraBio’s engineered Cytocaf proteins: synthetic, animal-free proteins designed to mimic biological signals that guide stem cell growth and tissue formation. Unlike conventional animal-derived proteins, Cytocaf proteins are reproducible, scalable and manufactured sustainably through microbial fermentation. Crucially, their unusual polymeric nature makes them unique in their ability to seamlessly integrate into existing 3D structures without the need for chemical modification.

By combining synthetic biology, materials science, and bioprinting, the project aimed to create a new tool for researchers developing treatments for OA and other joint conditions as an alternative to animal testing or complex microfluidic systems, that can be either ethically challenging, costly, or lacking in human relevance.

Project Details and Results

The project aimed to demonstrate that Cytocaf polymers could be integrated with hydrogel systems developed by CPI to create bioactive materials compatible with advanced 3D bioprinting technologies, for the purpose of developing scalable, animal-free models of OA.

MarraBio developed a library of Cytocaf polymers suitable for 3D mesenchymal stem cell (MSC) culture, including mimics of fibronectin and growth factors. CPI synthesised and formulated multiple hydrogel resins which consisted of biomaterials derived from waste streams. CPI also proved these printed biomaterials were non-toxic to human cells. The distribution of Cytocaf proteins were confirmed to be homogeneous within the resins by using fluorescent tagged Cytocaf proteins. Among the resins tested, dextran-based hydrogels incorporating Cytocaf fibronectin proved to be the most promising formulation.

Researchers at Royce evaluated the materials for printability and biological performance using advanced bioprinting, rheological, and materials characterisation facilities, alongside support from Royce application scientists.

Testing demonstrated favourable viscosity, shear-thinning behaviour, and gelation time for extrusion bioprinting, while initial biocompatibility studies with human fibroblast cells showed promising results. This enabled rapid validation of Cytocaf-functionalised bioinks under realistic manufacturing and biological conditions.

Impact & Next Steps

The project establishes a foundation for more accurate, scalable and accessible in vitro OC tissue models, with the potential to improve understanding of OA and accelerate therapy development. The work also opens new commercial opportunities for MarraBio’s Cytocaf platform, supporting SME growth and strengthening UK capability in advanced biofabrication and regenerative medicine.

Importantly, the project contributes to the UK’s 3Rs agenda (Replace, Reduce, Refine) by reducing reliance on animal-derived biomaterials and animal testing, while supporting more sustainable research practices.

Future work will focus on refining the composite biomaterials and developing increasingly sophisticated OA tissue models for tissue engineering, drug screening, and regenerative medicine applications.