Today's research has shown the viability and safety of 3D-printed tissue structures that can be used to promote tissue regeneration after implantation.The scaffolds demonstrated a promising performance in tissue healing, including the ability support cell migration, the 'ingrowth of tissues' and revascularisation (blood vessels growth).Andrew Dove, a Professor at the University of Birmingham's School of Chemistry led the research group. He is also the lead author of the Nature Communications paper. This paper describes the physical properties of scaffolds and explains why their shape memory is crucial for tissue regeneration.Professor Dove stated that the scaffolds are composed of interconnected, evenly distributed pores that allow for the diffusion of nutrients from surrounding tissue. This structure is retained by the scaffold when it is implanted in tissues. This allows for the infiltration of cells and encourages tissue regeneration and revascularisation.The 3D printing resin "inks" used to create the scaffolds were developed in a major biomaterials research programme led by Professor Andrew Dove from the University of Birmingham. 4D Biomaterials is a spinout of University of Birmingham Enterprise, Warwick Innovations and is launching the resins under the trade name 4Degra.The scaffolds had several advantages over other methods of filling soft tissue voids after surgery or trauma. They can be compressed up to 85% and return to their original geometry. They are compatible with tissues and non-toxic biodegradation.AdvertisementThis paper discusses several compositions of the 4Degra resins, which allow materials to be made in a variety of strengths. Each composition includes a photoinitiator as well as a photoinhibitor. This ensures that resins quickly turn to gel when exposed to visible light. It also allows for 3D printing of various scaffold geometries.Researchers proved that the materials are safe for cells. They also did mechanical testing to verify that they could recover their geometry, shape and pore size after being compressed. Additionally, tests showed that scaffolds can fill an irregularly shaped void in alginate Gel, which was used to mimic soft tissue.Laboratory studies have shown that the scaffold is susceptible to surface erosion and non-acidic products. This means that it allows for continuous, slow tissue infiltration.These findings were confirmed by a mouse model that simulates fat tissue implantation. The studies revealed infiltration of fibroblasts, adipocytes, and vascularization at two months. A tissue arrangement and macrophage presence was also observed that indicated normal tissue restoration, rather than scarred or damaged tissue.The researchers discovered small, mature blood vessels within the tissue after four months. Biocompatibility was also excellent for the scaffolds. The collagen capsule that formed around the implants was less than 200 millimeters thick. This is far below the 500 millimeter threshold for biocompatibility. There was also no calcification nor necrosis.AdvertisementAt four months, the scaffold was still 80%, which is consistent with the slow degradation predicted in laboratory studies. This indicates that the scaffolds will provide support for at least a year and allow for sufficient time for mature tissue to grow. As a comparison, the scaffolds used poly(L–lactic acid) (PLLA), and showed no significant decrease over the same period.Professor Dove says that 3D-printed materials have been a focus of tissue engineering. Material design must consider the fourth dimension of time. Void-filling materials are designed to provide mechanical support, biocompatibility, surface erosion characteristics, and biocompatibility."We have shown that highly porous scaffolds can be made with shape memory. Our processes and materials will allow for self-fitting scaffolds to take on soft tissue geometry in minimally invasive surgeries without deforming or applying pressure. The scaffold will erode with minimal swelling over time. This allows for slow continuous tissue infiltration and no mechanical degradation.4D Biomaterials made rapid progress in scaling up the production of 4Degra resin-inks in its laboratory in MediCity (Nottingham) (UK). Now, 4D Biomaterials offers technical grade material for commercial supply at 3D printing companies as well as medical device manufacturers.Phil Smith, CEO, stated that "We are interested in collaborating with innovative companies from North America and Europe to develop a new generation 3D-printed medical devices. This will translate the unique benefits of the 4Degra resinink platform into better treatment outcomes for patients." Phil Smith said that the first shipment to a customer was completed and that he is close to closing a funding round. He also stated, "We will make further announcements soon."
