Researchers at the École Polytechnique Fédérale de Lausanne (EPFL) have developed a new bone-like composite that may support faster bone regeneration. The material, which can be processed into porous scaffolds using 3D printing, uses naturally occurring enzymes to accelerate mineralization at room temperature. According to the researchers, this approach could open new possibilities for bone repair and tissue engineering.
The study focuses on synthetic materials based on hydroxyapatite (HA), a mineral that forms a key component of human bone. Conventional methods to produce HA-based materials typically require high temperatures. These energy-intensive processes also limit the integration of biologically active components, such as enzymes that can stimulate bone growth. The findings were published in Advanced Functional Materials.
3D-printable and injectable bio-ink
Researchers from the Soft Materials Laboratory (SMaL) at EPFL’s School of Engineering developed an alternative method based on a 3D-printable and injectable bio-ink. In this approach, the enzyme alkaline phosphatase is embedded in gelatin microparticles and incubated in a solution containing calcium and phosphate ions. The enzyme triggers the formation of hydroxyapatite crystals, which stiffen and strengthen the printed structures.
According to laboratory head Esther Amstad, the goal was to create scaffolds with mechanical properties similar to highly porous trabecular bone, which is found in vertebrae and at the ends of long bones such as the femur. The combination of mechanical performance, biological activity and energy-efficient processing could offer new opportunities for bone tissue engineering.
Controlled porosity for cell growth
A key feature of the material is its controlled porosity. In addition to enzyme-containing gelatin particles, the researchers add enzyme-free gelatin microfragments. These fragments melt during incubation, leaving pores within the scaffold structure.
After implantation, for example at the site of a bone fracture, these pores can be filled by healthy cells that contribute to new bone formation. By adjusting the number of gelatin fragments, the researchers can precisely control the scaffold’s porosity.
In the current design, around 50 percent of the scaffold volume consists of pores. This provides sufficient space for cells to infiltrate and gradually remodel the structure into natural bone tissue.
Rapid mineralization and mechanical strength
The mineralization process occurs relatively quickly. After four days, the composite can already support the average weight of an adult human on an area of about 1.5 by 1.5 centimetres. Within seven days, the scaffold becomes fully load-bearing.
In laboratory experiments, the researchers seeded the scaffolds with human stem cells and cultured them in a medium that supports bone growth. After 14 days, they detected collagen and the bone matrix protein osteocalcin, both indicators of active bone formation.
The enzyme-assisted process also resulted in HA scaffolds with compressive strength comparable to that of human trabecular bone. According to the researchers, the material can even be stronger than HA scaffolds produced using high-temperature manufacturing methods.
Potential for future clinical applications
The technique can be used with commercially available bioprinters and enables the fabrication of complex scaffold structures. The researchers suggest that the approach could eventually lead to injectable scaffolds that support bone regeneration.
In the longer term, such materials might allow patients with bone fractures to bear weight earlier than is currently possible with existing technologies. However, further research will be needed to assess the safety and effectiveness of the material in clinical settings.
3D bioprinting
Last year scientists from the Oregon Health & Science University (OHSU) Knight Cancer Institute described how technologies such as organoids, lab-grown tissues, organs-on-a-chip, and computational models help researchers study cancer development without relying on animal testing. These systems replicate key biological processes, allowing scientists to observe how tumors originate and progress.
Researchers are also using 3D bioprinting to create realistic tumor environments, including models with patient-derived cancer cells. This enables the study of early tumor formation and the identification of biomarkers that may signal cancer before symptoms appear. Combined with AI-driven modeling, these approaches support the emerging concept of “cancer interception,” which focuses on detecting and stopping cancer at its earliest stages.
